Contents for February 2004

EDITORIAL
Rehabilitation, wetlands and a green building

UPFRONT
News

IDENTIFYING INVADERS
Biological control of Queen of the Night

BOOK REVIEW
Mountain Flowers

TREE OF THE ISSUE
Chris Bowden chooses the common Karee

FEATURES

Urban upgrading in central Johannesburg

Extensive rehabilitation from plantation to forest and fynbos

Environmental controls at golf course estate

Future Normal – mainstreaming green building

Rehabilitation in a headwater catchment of an Eastern Cape River

-----

EDITORIAL

Rehabilitation, wetlands and a green building
Rehabilitation of degraded land to natural vegetation is the main thrust of this issue. Pezula Private Estate, an environmental project worth watching as it may provide a blueprint for projects of this nature in the future, has started its extensive rehabilitation programme. Land on which exotic timber has been grown for the last 60 years is being returned to natural vegetation, and environmental manager Jessica Hayes maintains that there are no known examples anywhere of such extensive rehabilitation from commercial plantation to coastal fynbos and afromontane forest. The rehabilitation plan at Pezula has been devised by botanical consultant Jan Vlok and the strategy is one of “adaptive management”. The success of the rehabilitation will be monitored on an on-going basis and depending on the whether the results are favourable or otherwise, the methods will be revised, accordingly. (See article on page 18.)

Sparrebosch is Pezula’s next door neighbour adjacent to the eastern Head at Knysna and rehabilitation work to return disturbed areas of that site to coastal fynbos has been underway for a number of years. (See page 24.) According to environmental control officer, Cathy Avierinos, the fynbos communities have been monitored using quantitative analysis since pre-construction. She says that with the removal of regular burning, mowing and grazing pressures, the fynbos is returning to a more natural state of its succession. The most successful method of transplanting the fynbos at Sparrebosch has proved to be by removing entire sods and translocating these directly to areas scheduled for rehabilitation: “Fynbos loves fynbos topsoil,” she says.

Although Cathy makes no mention of it, in her article, a cover crop of veld grass was used at Sparrebosch in an initial attempt to create a suitable microclimate for the return of the coastal fynbos – there are still remnant patches of the planted grass to be seen amongst the rehabilitated fynbos. Pezula is going the natural route of allowing the coastal fynbos to regenerate from its seedbank after a managed burn, without intervention of this nature. This should make for an interesting comparison.

I am writing this editorial on 2 February, World Wetlands Day: the day that marks the date of the signing of the Ramsar Convention, in 1971. This year’s World Wetlands Day theme is ‘Wetlands at Work for us’ – and it highlights the unique value of wetlands to both the environment and mankind. Wetland protection and rehabilitation is a core focus area of the journal and, in this issue, Lil Haigh of Rhodes University describes relatively low-budget techniques used to rehabilitate a wetland, degraded by invasive vegetation, in Featherstone Kloof outside Grahamstown. (See page 32.) Our front cover tells the story of an enterprising and innovative project initiated by Midrand resident Richard Shute which will hopefully make a small difference to saving the wetland habitat of the Giant African Bullfrog. We encourage readers to be proactive and “adopt a Bullfrog” by sms. (See page 6.)

Leigh Darroll shows that the application of green principles in design and construction can become the norm in commercial building in the urban environment, through her article on the ‘Green Building’ at Westlake Business Park in Tokai, Cape Town. Office premises that are energy conscious, environmentally responsible and financially viable. (See page 28.) - Carol Knoll

-----

UPFRONT

Long-term ecology for managing ecosystems  in kruger national park
A consultancy service set up at Oxford University aims to help managers having to make decisions on environmental issues by providing information about how environments have evolved over long timescales. Called BioGeo-Sciences for Conservation (BGSC), it is backed by a specialist laboratory that uses fossil records such as pollen and charcoal to reconstruct how forests, savannahs and other areas developed in response to changes in climate, disturbances by fire and people, and to changes in soil fertility and water availability over hundreds to thousands of years.

Dr Kathy Willis, one of three principals of BGSC, also heads the Oxford Long-term Ecology Laboratory. She says: “What is unique about this service is the way in which it links together many techniques to provide information that is not normally accessible to those involved in environmental management. They tend to base their decisions simply on knowledge of current ecological patterns. We take a long-term perspective, sometimes over thousands of years, to help manage biodiversity today.

“One of our projects, for example, is looking at the dynamics of the ecosystems in the Kruger National Park. It was long believed that preserving these ecosystems would mean preventing vegetation from changing. But trying to keep such an environment stable is fighting a losing battle. Current ecological thinking recognises that variation is normal. Our work looks at how the vegetation of this area has developed over hundreds of years – which will help the park scientists to decide when to let changes in vegetation run their course and when to intervene.”

The researchers collect data by coring – that is boring a long, thin tube into swampy ground in which pollen has been preserved for thousands of years. The core extracted provides them with a layered sample of the sediments that have accumulated over time. By analysing the pollen throughout the sample, the researchers can develop a chart of the plant species that were present at each point in time. Techniques such as radio-carbon dating are used to show the timescale over which the vegetation changes took place.

The team also uses other approaches to understand environmental change in an area. These include dendrogeomorphological techniques that can explain the nature and severity of slope movements. These techniques use the changing nature of tree rings and trunk growth to work out whether the trees have been affected by soil movements, landslides or other geomorphic events
Email: environmental@oxconsulting.co.uk Website: www.oxconsulting.co.uk 

Grassland management at Pretoria botanical garden
Pretoria National Botanical Garden has an expanse of natural grassland on its property which has had fifty years to recover from agricultural activities and is used as the basis for a grassland ecology programme for children visiting the Environmental Education Centre at the Garden (see UGF Sep/Oct 2000). The area has been long in need of a formal management programme and grassland ecologist George Bredenkamp, acting as an interested member of the Botanical Society of South Africa (BotSoc), has recently compiled a working plan on management procedures for the grassland. 

In March last year, curator Karin Behr and Bredenkamp visited the site and made a preliminary assessment of the condition of the grassland. It was noted that the core area of the grassland was in a fair condition, with a great variety of plant species in evidence. The edges of the grassland were variously affected and footpaths criss-crossed certain areas. Individuals of the dangerous new Pom-pom Weed, Campuloclinium macrocephalum, had established in the grassland.

The decision was taken to compile an ecologically based management plan including extensive research, management actions and the development of specific sites for educational purposes. Visitor access and the use of information boards and a booklet for visitors was an-other aspect that was discussed. In May last year, it was decided that the more degraded of the two portions of grassland should be developed as an enriched grassland system, to be supplemented by the planting of grassland species, while the area that was in good condition should be managed sustainably as a natural grassland ecosystem, including burning when it was really necessary. The grass has been slashed every year in late winter in the past.

A burn was done in late August last year and the accompanying photographs were taken in spring after the burn. Bredenkamp commented that even though there had been little rain, the grassland had come to life after the burn. He said the burn was bound to make a difference because even though slashing had been done in previous years, the grassland had become quite moribund. He said to achieve a fairly cool burn, it was ideal to wait until immediately after the first rain shower. He added that because of the lack of rain, the fire had possibly been a little hotter than was ideal but that this had helped to get rid of the moribund material. He said there was a noticeable increase in the flowering of herbs and geophytes after the fire and that all three orchid species (Eulophia spp) present had been stimulated to flower. Trichodesma physaloides, commonly known as Chocolate Bells, flowered prolifically all over the natural grassland. Pentanisia angustifolia (narrow leaved Pentanisia) came through strongly and Gnidia kraussiana, sometimes called the Lesser Yellow Head, had flowered better than it usually did.

Bredenkamp said that because rain had been scarce, the full effect of the burn would probably not come to the fore this season but that the slightly better flowering, generally, meant that there would be better seed production. This would supplement the seedbank and more plants would germinate once the rains came.

Bredenkamp is not in favour of a rigid burning regime and he says the decision to burn will be taken in future based on the previous season’s rainfall and the extent of the accumulation of moribund material. He says the plan should be entirely flexible and monitoring the grassland will show whether continued slashing is necessary in the future. As he pointed out, grassland needs to be grazed and in the absence of an adequate population of grazing animals, slashing may need to be continued. The Scrub Hare population is on the increase and the intensity of grazing will have to be carefully assessed.

In November 2003, seven staff members from the National Herbarium and four BotSoc members walked through the two sections of grassland documenting all the plant species known to them and this list of 131 species will be available shortly. Researcher Pieter Bester has been taking photographs for record purposes on a weekly basis since the burn.    

2004 – The year of the Giant Bullfrog
Mobile phone game to raise funds for wetland conservation 

Attempts to rehabilitate and conserve natural water storage and management systems are to be welcomed.

One such initiative is a mobile phone response-based instant text messaging (sms) game, which was launched in January 2004 and will be active for the duration of what has summarily been declared ‘The Year of the Giant Bullfrog’.

The Giant Bullfrog is a wetland frog species threatened with extinction that has been singled out as a flagship life form (because its populations are in dramatic decline) with a temperament and character ‘marketable’ enough to lead a campaign to identify, research, rehabilitate and conserve South Africa’s strategic wetland resources. This species does not respond to captive breeding programmes, so the only effective conservation strategy lies in restoration and protection of its wetland and grassland habitat.

Mobile phone users keen on ‘adopting’ a virtual bullfrog simply send an sms, reading ‘BULLFROG’ to 082 003 5348 to begin the game. Players begin the game with three ‘lives’ and get presented with ‘threats’ along the way.   When a certain number of stages have been passed through, male players will be able to ‘fight’ their friends’ bullfrogs, losing them a ‘life’ in the process and female players will have an opportunity (during this leap year!) to send ‘kisses’ to ‘princes’ that they fancy in the hope that they will turn into ‘bullfrogs’.  These aspects of the game are true to the lifecycle events of the Giant Bull-frog and promise a lot of interactive fun!

Consequently, the natural environment is assigning special significance to the IT term ‘communications convergence’, when email, sms and an informative website – at www.GiantBullfrog.com  – integrate to make possible an ecological ‘adoption’ game that informs and entertains.

The focus and beneficiary of this fresh approach to the ‘adoption’ process of endangered or threatened animals is Africa’s Giant Bullfrog…a noble beast and ecological flagship of its wetland habitat.

Most noticeably, the general public has become aware of the decline in numbers of these Bullfrogs which used to emerge in abundance after summer rains. Mainly threatened by habitat destruction, road fatalities and electric fencing, this amphibian also forms part of the diet of some communities.

The website offers visitors a web page-to-mobile phone sms window that allows users to report sightings of wild flora, fauna and birds to a Wetlands Watch handset and to report suspected contraventions of environmental ordinances to Gauteng’s Department of Agriculture, Conservation, Environment and Land Affairs (DACEL) hotline.

The interactive sms game allows cellular phone users to ‘adopt’ a virtual Giant Bullfrog from the comfort of their handsets, name their Bullfrog, participate in its life activities with other adopting players and take part in the amphibian’s sequence of lifecycle events to the completion of the game. The game is played on a premium R5 sms line, the events and two life activities costing R5 each to navigate. To play the game to conclusion costs the player R60 and the game will remain active throughout 2004. Players are thus free to establish their own level of expenditure in the game.

The game remains as true as possible to the Giant Bullfrog’s lifecycle schedule and it is supported by a series of emails that expand on the topics referred to in each game level and feature photo images.

‘We set out to establish a meaningful relationship between ‘adopter’ and Bullfrog, and the main challenge has been to reduce sufficient biological information to fit into the sms message size parameter, being a maximum of a hundred and sixty characters,’ says Richard Shute, project co-coordinator. “This has had to be augmented by information about the rules of the game so that it remains a stand-alone activity, independent of its internet components.”

The Giant Bullfrog – with its ancient ancestry – stands to benefit from modern technology opportunities.
Contact Richard Shute for further information. Cell: 082 954 0214. Email: webmaster@GiantBullfrog.com Website: www.GiantBullfrog.com
Sms line for ‘adopting’ a virtual bullfrog: 082 003 5348

Extinction risk: IUCN red list of threatened species
The IUCN Red List of Threatened Species is the world’s most authoritative inventory of the conservation status of plants and animals. Thousands of scientists and conservationists from all over the world contribute to this rapidly expanding list, compiled by the World Conservation Union (IUCN), through its Species Survival Commission (SSC) and partner organisations.

Since the release of the 2002 Red List, more than 2 000 new entries have been added and 380 taxa (species, subspecies, etc) reassessed. The IUCN Red List now includes 12 259 species threatened with extinction (falling into the Critically Endangered, Endangered or Vulnerable categories). A total of 762 plant and animal species are now recorded as Extinct with a further 58 known only in cultivation or captivity.

Some notable new additions to the List this year include 1 164 Ecuadorian plants, 125 Hawaiian plants, 303 cycads and 35 Galapagos Island snails. The many movements into higher threat categories include one of the world’s largest freshwater fish, three neotropical primates and six albatrosses.

The Red List provides the best available knowledge necessary for sound conservation action. Human activities may be the main threat to the world’s species but humans can also help them recover – the Chinese crested ibis, the Arabian oryx and the white rhino are just a few examples.

Island populations of native plants and animals are being lost through the effects of invasive alien species which are a major threat to global biodiversity. Tristan da Cunha, St Helena, Ascension and the Falkland Islands (Malvinas) in the South Atlantic have developed their own unique suites of animals and plants that are extremely vulnerable to human disturbance. As on many other islands around the world, habitat destruction, introduced grazing animals and predation by and competition with invasive species are unrelenting. Invasive species have caused the extinction of four of Ascension’s plants that are found nowhere else on earth.

As the native plants on Hawaii decline, the remaining individuals are out-competed by introduced weeds and attacked by insects, many of them also introduced. Loss of pollinator species that co-evolved with particular plants means there is little or no chance for them to reproduce. Add to this, housing development, tourism infrastructure and agriculture, and the future for the Hawaiian flora looks grim. Of the 125 endemic (found nowhere else) Hawaiian plant species added to the Red List this year, 85 are threatened and the number is set to increase. Threats include habitat degradation by pigs, competition with alien plant species (such as the prickly Florida blackberry Rubus argutus and Koster’s curse Clidemia hirta), predation by rats, trampling or collecting by humans.

It is not only Hawaii’s plants that are threatened by alien invasives. The Vulnerable Newcomb’s snail (Erinna newcombi) demonstrates the effects of invasive invertebrates on Hawaii’s endemic fauna. Newcomb’s snail occurs only in remote waterfalls, seeps and springs of six stream systems on the island of Kauai where a variety of intentional and accidental introductions of non-native fish, snails, flies and frogs threaten its survival. The most serious threat is predation from the rosy wolf snail (Euglandina rosea), introduced to Hawaii in 1955, which has also wiped out many Polynesian and Mascarene island endemic species.

Galapagos Island snails are also in a precarious situation – 49 species were assessed or reassessed for this year’s List and many of them are Critically Endangered, possibly already extinct. Invasive species such as goats, pigs, and fire ants are mostly to blame.

Meanwhile, continental species are not faring well either. Of the Neotropical primates, three species have moved up into higher threat categories. The Mexican black howler monkey (Alouatta pigra) has moved up to Endangered. There has been a 56% loss of habitat already and with continuing loss, the population is expected to decline by over 70% in the next 30 years.

The variegated spider monkey (Ateles hybridus), found only in Colombia and Venezuela, moves from Endangered to Critically Endangered, and is at extreme risk. Threatened by habitat loss due to urban growth, agriculture and cattle grazing, the pied tamarin (Saguinus bicolor) also moves from Endangered to Critically Endangered.

Asia’s Mekong giant catfish (Pangasianodon gigas), one of the world’s largest freshwater fish (growing up to 3m in length and weighing up to 300kg), is found only in the Mekong River basin area (Viet Nam, Cambodia, Thailand and Lao PDR) and has been upgraded from Endangered to Critically Endangered. This is largely due to over-fishing, habitat loss (such as through siltation and dredging) and obstruction of migratory routes through dam construction.

South Africa’s riverine rabbit (Bunolagus monticularis) is uplisted from Endangered to Critically Endangered. Found in the central Karoo region, this species is now estimated to number fewer than 250 breeding pairs. With ongoing habitat loss and fragmentation, trapping, and predation by feral cats and dogs, the population is expected to decline further.

The Red List is making great progress in increasing its number of plant assessments. All known cycad species have now been assessed, and there is also complete coverage of the conifers.

Cycads, the oldest seed plants on earth, are now also amongst the most threatened plants. Two species have already gone Extinct in the wild, and more are likely to join them. This year, 303 cycads were evaluated and 155 of them (more than 50%) are threatened. This makes cycads one of the most threatened groups of species currently on the Red List.

The black-browed albatross (Thalassarche melanophrys) has moved from Vulnerable to Endangered. It is one of the most frequently killed species in longline fisheries and also dies in trawl fisheries.

This year 175 sharks and rays were assessed or reassessed for the Red List. There are now 57 species and a further 19 stocks assessed as threatened.

The Northeast Atlantic subpopulation of the spiny dogfish (Squalus acanthias) is now Endangered while the Northwest Atlantic subpopulation is Vulnerable. High demand in European markets has stimulated fisheries in the Northwest Atlantic and intensive fisheries in the Northeast Atlantic have been yielding declining catches since the early 1960s.

Joining the List as Endangered is the Mediterranean subpopulation of the short-beaked common dolphin (Delphinus delphis). Its population has declined more than 50% in the Mediterranean region over the last 30-40 years, due to reduced dolphin prey in the Mediterranean because of over-fishing and habitat degradation. High levels of Polychlorinated Biphenyls (PCBs) found in these dolphins compared to dolphins in other areas are also cause for concern.

Marine species are widely believed to be resilient to extinction but they are rapidly proving that they are just as vulnerable as their land-based counterparts. The need for improved policy and practice in managing marine environments is critical.

IUCN/SSC Red List Programme Officer, Craig Hilton-Taylor commented: “Above all, the Red List is a wake-up call to all of us. By working together we can help conserve what remains of the Earth’s biodiversity.”

Contact Craig Hilton-Taylor. Email: craig.hilton-taylor@ssc-uk.org Website: www.iucnredlist.org 

Local municipalities are encouraged to enter the International Awards for Liveable Communities
The LivCom Awards were launched in 1997 under the title ‘Nations in Bloom’ and endorsed by the United Nations Environmental Programme. The Awards competition focusses on Best Practice in the management of the local environment. Communities from over 50 different countries have participated and each year those delegations that have met at the finals of Nations in Bloom have formed partnerships to exchange practical experience. This year the competition, which deals with issues involving quality of life, has taken on a more appropriate name.

The only South African community that has participated in the competition this far is Tshwane (Pretoria) and they were acknowledged, once again, in 2003 with second place in the large city category. Tshwane also won the Criteria Award for Community Involvement. Other communities in South Africa are encouraged to enter as environmental challenges do not respect international or cultural borders and it is important that everyone with a responsibility for quality of life issues should be aware of international best practice. An effective way of achieving this is by participation in a major international event: The LivCom Awards.

Chelsea in Canada won the Criteria Award for Environmentally Sensitive Practices. At the Finals, the Mayor revealed the city’s objective of developing pesticide-free horticulture in parks and green space management. Pesticide by-laws have been established and the municipality has implemented a programme involving public awareness of ecological alternatives and inspections to ensure effective application of the by-laws. The successes achieved have encouraged other communities in Canada to pursue the same policy.

The most striking demonstration of Heritage Management at the 2003 Awards was presented by Quanzhou in China. Showing respect for its long heritage, the community has renovated many examples of ancient statues, temples, houses, waterways and religious buildings and reinstated cultural festivals.

The Finals of LivCom 2004 will be held in October in Niagra, Canada. The closing date for registration is 31 May 2004 and registration forms can be obtained by emailing Alan Smith:
info@livcomawards.com Website: www.livcomawards.com

Tortoise release at Fancourt's links
In keeping with Fancourt’s policy of creating a wildlife habitat on The Links course (see UGF Nov/Dec 2003, Editorial), twenty tortoises of varying ages were released onto the course in early December last year, after the activities related to the President’s Cup were over.  Jennifer Strong has been running a tortoise rehabilitation centre for the past ten years and she recently chose The Links as a suitable habitat for the release of her tortoises. Over the years, she has become known and respected as a rescuer of tortoises that have been run down on highways and injured.

Jenny was given her first permit to keep tortoises ten years ago and subsequently her property has become overrun with the tortoises that have been brought to her for rehabilitation by members of the public. The twenty tortoises donated to The Links vary from two to forty years in age and, according to greenkeeper Ivor Peterson, they appear to have settled down well on the golf course. He has spotted a few of them looking healthy on the cart paths and returned them to longer grass for their own safety.

Fancourt plans to do further introductions of wildlife into the man-made grassland/wetland environment of The Links, now that the President’s Cup is behind them. UGF will continue to give coverage to wildlife releases and other aspects of environmental management at The Links.

Alien clearing uncovers new species
A new species of the Ixia plant genus, a member of the Iris family (Iridaceae), has been discovered on the Rooisand Reserve near the Arabella Country Estate, just outside Kleinmond. Louis Mostert, an amateur botanist, made the discovery in an area that had been cleared of alien vegetation for the first time in about 40 years. For many years the bulbs of this new Ixia species have lain dormant, choked by invasive alien vegetation.

Commenting on the find, Jasper van der Westhuizen, Manager of the Arabella Country Estate said: “Arabella South Africa has entered into a 50-year agreement with the Western Cape Nature Conservation Board to manage and develop the adjacent Rooisand Nature Reserve for the benefit of the community. Part of our involvement includes clearing alien vegetation from the reserve. The discovery of this Ixia species is a wonderful reward for the clearing that Working for Water has done in the reserve to date.”

The Kogelberg Biosphere Reserve of which the Rooisand Reserve is part, boasts about 1 650 indigenous plant species, 77 of which are endemic to the area, while 213 species of birds have been identified on the reserve to date.

In addition to the prolific birdlife in the area, a rare rufus form of the Spotted Eagle Owl laid her eggs, and raised three chicks on the balcony of the Première Restaurant at the Western Cape Hotel & Spa on the Arabella Country Estate. The chicks have all successfully fledged and are out of the nest.

The estate is located in the Kogelberg Biosphere Reserve which is one of the richest areas of plant diversity in the Cape Floral Kingdom. It is situated on the sensitive Bot River estuary, adjacent to the Rooisand Nature Reserve.      
Contact Jasper van der Westhuizen or Norris Snyders at Arabella Country Estate on 028 284 0000

Plan to build World’s biggest wind farms
The world’s largest offshore wind farms are to be constructed in the UK and plans to develop 15 new sites have been announced. These power generating ventures are expected to produce electricity for more than one in six households by the end of the decade. The new sites will be built in three areas of shallow sea around the Thames Estuary, Greater Wash and in the north-west of England.

Energy Minister Stephen Timms said: “This is the biggest expansion of renewable energy anywhere in the world and demonstrates that we are serious about moving towards a cleaner, greener future.”

Plans have now been put forward that will provide electricity for four million homes. The proposals include the world’s largest offshore wind farm, about 40 km off the Lincolnshire coastline, which could have up to 250 or more turbines. The UK’s first large-scale offshore wind farm at North Hoyle in Wales was commissioned in November. The government is committed to providing 10% of the UK’s energy from renewable sources by the year 2010, with the aim of doubling this figure by the year 2020. Wind farms are likely to account for 80% of this capacity.

Up to date, the UK wind industry has installed the capacity of some 640MW in projects onshore and offshore (including 100MW commissioned in 2003) and generates clean power equivalent to the requirements of more that 400 000 households.   
Website: www.dti.gov.uk 

CMA Awards for excellence
The Concrete Manufacturers Association (CMA) is calling for entries for this year’s Awards for Excellence competition, the 10th such event, and one which is held biennially. The awards are made on a regional and national basis.

CMA director John Cairns says that the purpose of the awards is to recognise excellence in the aesthetic, engineering and creative use of concrete manufactured products, and to honour those involved in the application of these products through design and construction.

Entry forms are available and the closing date for entry submission is 28 May. The competition is open to all individuals, partnerships and companies in South Africa and neighbouring countries, and entries may be submitted in the following categories:
*            Concrete Block Paving
*            Concrete Roof Tiles
*            Concrete Masonry
*            Concrete Retaining Block Walls
*            Suspended Concrete Floor Slabs
*            Other Concrete Products

The first four categories each have a sub-category referred to as Vintage, which is for projects over 10 years old. “This category was introduced in 2000 and is growing in popularity. It proves that concrete products are not only durable but also retain their aesthetic appeal over the long-term,” says Cairns.

National awards are made to the winning entry of each sub-category. These awards, as well as the inland regional awards and the four CMA floating trophies, will be presented at a gala awards banquet on 9 October at the Theatre on the Track in Kyalami.
Enquiries: John Cairns of the CMA. Tel: (011) 805 6742.David Beer. Email: bigsky@ibi.co.za

-----

IDENTIFYING INVADERS

Biological control of Queen of the Night
UGF’s regular column to help with the identification of invasive species and their control

Cereus jamacaru
This cactus species, commonly known as Queen of the Night or the Peruvian Apple Cactus, was introduced from South America as an ornamental barrier plant and is now a declared Category 1 weed in South Africa. It invades bushveld and rocky ridges, replacing indigenous vegetation and preventing animals from finding food and shade. The plant is abundant in Limpopo Province and Mpumalanga but also forms stands locally in the North West Province and Gauteng. It is still fairly common in the gardens of Pretoria and Johannesburg.

Its attractive white flowers open at night and flowering occurs from November to January. Its seeds are spread by birds and monkeys that feed on its succulent fruit. It can be mistaken for the indigenous Euphorbia ingens (Naboom) but it does not exude the milky latex typical of euphorbia species and its branches are a blue-green colour with prominent ribs.

Every attempt must be made to eradicate this plant. It should be dug out and burnt, because chopped or broken branches can take root and form new plants. The herbicides, MSMA and MSMA 720SL, are registered for Queen of the Night as both foliar sprays and stem injections.

There are two biological control agents that have been released that are effective on Cereus jamacaru and both these insects were originally used in Queensland, Australia to control the cactus Harrisia martinii (Harrisia Cactus). According to Hildegard Klein of the Plant Protection Research Institute (PPRI), the two agents were introduced into South Africa for this purpose, but it was hoped that they would also attack the Queen of the Night.

Considerable damage has been caused to Queen of the Night by Alcidion cereicola which was released in 1990 and is a cactus stem borer. Larval feeding causes significant damage – the older larvae destroy the vascular tissue thereby killing the affected stems, so that the plants collapse and die.

Moderate damage has been caused by the mealy bug, Hypogeococcus pungens, which manifests through twisted, distorted tips and sideshoots covered with a white, wooly mass of insects. Flower buds are also attacked and the few fruit that continue to be produced are distorted. Because the cactus is a much larger plant than the Harrisia Cactus, it takes much longer to die, but plants severely attacked by the mealy bug are likely to stop growing altogether and because both flowerbuds and fruit are attacked, the invasiveness of this plant which reproduces mainly from seed, will be restricted.      

According to Klein, the two biocontrol agents in combination are extremely effective and have been known to kill even the largest plants. The stem borer, unfortunately, breeds very slowly and is not yet freely available for redistribution. The mealy bug was re-released in Pretoria’s Faerie Glen Nature Reserve during National Weedbuster Week, in October 2004.

Klein reports that in most parts of the country, biological control by means of the mealy bug is effective and there is no need for chemical control. However, in the warmer regions north of the Magaliesberg and in the Bronberg, the cactus reaches fruiting age earlier, and with plants of over 1m in height, reliance should not be placed on the biological control alone – chemical control with MSMA is necessary. South of the Magaliesberg, the mealy bug (in conjunction with the stem borer, if available) is adequate for any size plant. She says that in any region, isolated small plants can be uprooted and placed onto a surface of hard rock or suspended in a tree to prevent rooting.
Contact Hildegard Klein of the PPRI concerning the biocontrol. Email: Riethdb@PLANT2.AGRIC.ZA

-----

BOOK REVIEW

Mountain Flowers - A Field Guide to the Flora of the Drakensberg and Lesotho
Author: Elsa Pooley
Publisher: The Flora Publications Trust

Once again Elsa Pooley provides the kind of in-depth information we have come to expect from her field guides, in this beautiful book on the wild flowers of the Eastern Mountain Region (EMR) – the uKhahlamba-Drakensberg and the Lesotho mountains. Pooley says the area has close to 400 endemic species – that is plants found only there and nowhere else in the world. In 2000, the uKhahlamba-Drakensberg area was proclaimed a World Heritage Site for its rich diversity of plant species, spectacular landscapes and its rock paintings. Africa’s greatest concentration of rock art is to be found in the caves and overhangs of these mountains.

The book is dedicated to Olive Hilliard and Bill Burtt, “plant explorers and taxonomists whose work has enhanced our knowledge and understanding of the Drakensberg Flora”. All the photographs, some of them showing the extraordinary habitats in which the wild flowers grow, were donated and particular thanks are given to the following photographers who donated a significant number of photographs: Martin von Fintel, David McDonald, Lal Greene, Neil Crouch, Olive Hilliard and Bill Burtt, Tony Abbott, Peter Linder, Pam Cooke, Mike Hirst and Darrel Plowes.

The book is colour coded for ease of use in the field and the known locations of the 2 200 flowering plants covered in the book are shown on distribution maps. Line drawings of plant parts help with identification, along with information provided in bold that distinguishes various species from similar species. The traditional medicinal and magical uses of many of the plants have been included, as have their uses as food or fuel plants. The flowers of the magnificent Gladiolus saundersii, an EMR endemic, for example, are eaten as salad or cooked as a pot herb; while Helichrysum trilineatum grows in large colonies and is collected in bundles, dried out and used for fuel in Lesotho.

Great care has been taken to provide as many common names as possible. Pooley comments that the meanings of the African names can be very evocative and she gives some examples: the Sesotho name ‘lepata-maoa’ can refer to any fern that hangs from damp rocks and it means ‘the one hiding in the caves’; whereas Merx-muellera macowanii, a tall wiry mountain grass, is called ‘mohlaba-pere’, ‘the one which pricks the horses’. Knowing that it would be a Herculean task, it would be lovely, all the same, to see a botanical field guide which provides as many English meanings for the African names as possible – or merely a list of South African plants with their local names translated.

The guide also provides information on ecological relationships, where these are known: Gladiolus flanaganii, which goes by the highly descriptive common name of Suicide Gladiolus, because it is found hanging from the crevices of wet basalt cliffs near the summit, has long tubed flowers specially adapted for pollination by the Malachite Sunbird which migrates to higher areas, when the plant is in flower, to probe for its nectar; while Euryops laxus (Harpuisbossie) is one of the first plants to shoot up after a grass fire; and orchids of the genus Disperis are pollinated by various oil collecting bees.

In her talk at the launch of the book in Gauteng, Pooley encouraged people to visit the area to see the flowers, calling the Sani Pass one of the wonders of the natural world and mentioning that wildflower tours left from Underberg. She said the area around the central car park at Witsieshoek was like a garden in late February. There are 150 species of orchid in the Drakensberg and most of them flower in January/February, while there are 15 species of gladiolus, 11 species of Euryops, five of which are endemic, and seven species of Diascia, three of which are available commercially and used as garden plants in KZN.

She pointed out the hardiness of the well known, widely distributed, Bulbine abyssinica, saying that it grew near the basalt at the summit and coped remarkably with the snow and ice. She spoke about unusual plants such as Cyrtanthus epiphyticus (Boomlelie) which grows in trees in the rocky cliffs; and about the waterlily Aponogeton ranunculiflorus, with its submerged leaves and white cup-shaped flowers, which is only known from the rock pools and tarns (small mountain lakes) of the Sehlabathebe area. She said that wild flower lovers should visit both the southern and northern Drakensberg as the flowers varied considerably.

The Flora Publications Trust website: www.floratrustkzn.com

-----

TREE OF THE ISSUE

The common Karee
Landscape contractor Chris Bowden of Landscape Solutions has chosen the common Karee as the Tree of the Issue. Chris is the immediate past chairperson of the Gauteng branch of the South African Landscapers Institute (SALI). He is also SALI’s national chairperson elect and will take up office in June.

He favours Rhus lancea for a number of reasons but predominantly because of the somewhat contorted, craggy growth habit of its trunk and branches and its dark, fissured bark. He finds these aspects of the tree particularly aesthetically appealing and says the Karee attains this look within five years. He maintains it can be used effectively in a variety of different types of landscape: open woodland – the office park environment; with pruning to lift the crown, it will serve well as an evergreen shade tree in a parkland; alongside streams and on riverbanks, where its slightly weeping habit will look appropriate; and for screening purposes or as a windbreak.

“With the threat of drought and water restrictions, the drought-resistant Rhus lancea will be a good tree to choose for almost any larger landscape. The tree is also not fussy about soil type and does well even in poorly drained soils. The roots are non-aggressive and termite proof because of their high tannin content. It is an ideal street tree,” were his comments. “Aside from being very drought hardy, it is very frost resistant. It is definitely a tree for the larger landscape, however, as its wide crown needs an unrestricted space in which to develop. Its ripe fruit attracts fruit-eating birds such as bulbuls, and francolins forage under the tree eating the fallen fruits.”

Chris has through experience with both Rhus lancea and Rhus pendulina (White Karee) found the former to be the better tree for a number of reasons. He maintains that the latter manifests partial defoliation and is, in fact, semi-deciduous in some areas. It grows too fast in the irrigated landscape and he has known the crown to become too heavy and to cause the trunk to split. Lastly, it is prone to caterpillar infestation and it seems to be only the Burchell’s Coucal that preys on these caterpillars. He is of the opinion that the White Karee has been over-planted in the urban environment, whereas the Karee – the better tree – is under-utilised. He says this is probably so because growers find the tree easier to propagate and it grows quickly. It is therefore more saleable. “It is not as though Rhus lancea does not grow relatively quickly (± 800mm per year). The only problem I have known with it is hardly a problem – it gets a slight leaf curl but is best left untreated as it sorts itself out,” concludes Chris.

-----

Urban upgrading in central Johannesburg
Recently the Gauteng Provincial Government (GPG) confirmed its plans to consolidate and upgrade what is referred to as the Government Precinct in the Johannesburg CBD. This follows Province’s purchase of seventeen buildings which together establish a dominant presence of provincial government departments in the central to southwestern quarter of the city.

Core to the precinct is the City Hall, Harry Hofmeyer Parking Garage and the Beyers Naude Gardens – that area which, with the City Library, was formerly defined as the civic spine – running east-west between President and Market Streets. Additional buildings are located to the north and south of this core, within an area stretching from Rissik Street on the east to Kort Street on the west, and bordered by Pritchard Street on the north and Main and Fox Streets on the south. In total the GPG has taken up 150 000m2 of office space. The conceptual plan for the precinct also proposes the demolition of a number of buildings, to make way for public open space south of the Beyers Naude Gardens, and the rerouting of a section of Market Street, between Harrison and Sauer, below ground.

In his weekly dispatch of 21 November last year, Neil Fraser, executive director of the Central Johannesburg Partnership, reported that at the handing over ceremony of the City Hall and adjacent amenities – which the Gauteng Legislature had purchased from the City of Johannesburg – speaker of the Legislature, Firoz Cachalia, said that the building would be restored, upgraded and modernised. Cachalia also emphasised the importance of preserving a sense of public domain… “by putting to rest discriminatory distinctions and investing in public spaces as opposed to shopping malls.” This is good news for the city and its people. Cachalia is quoted as saying, “I can see no reason why we should not once again be afforded the pleasure of listening to Mozart’s flutes or enjoying the musical Shanti Town with Miriam Makeba.” This kind of public amenity, in a well-managed precinct, and potentially complemented by a network of public squares and green open space, would make the city a much more hospitable place.

A spokesperson from the Gauteng Department of Transport and Public Works explained to Urban Green File that a feasibility study undertaken by the Province indicated that it would be more cost effective for the GPG to purchase the buildings than to continue leasing space as it has done for the past few years. This led to the development of a conceptual framework for a defined Government Precinct by architects and urban designers, Ngonyama Okpanum. The intention is to refurbish and upgrade the buildings where necessary and to establish a clean, secure, 24/7 precinct in the city, which will add significant momentum to the regeneration of Johannesburg.

The Department emphasises that the framework is conceptual at this stage and is yet to be refined. It is envisaged that the precinct would be developed through a public-private partnership and in consultation with the relevant local authorities.

The issue of the demolition of five buildings which are protected by heritage legislation because they are more than 60 years old has already been highlighted in the daily press. On this, the Department states that it is following due procedure in terms of heritage legislation and the project will proceed accordingly. A Heritage Impact Assessment, prepared by a specialist team under the guidance of Ngonyama Okpanum, has been presented to the South African Heritage Resources Agency (SAHRA) and, at the time of going to press, this was open to comment and input from interested and affected parties.

“Our objective is to improve the office space and the environment in the precinct, and so to contribute to rejuvenation of the city as a whole,” the Department says. “With our investment in these buildings and our commitment to the Government Precinct, we bring a substantial and stable workforce into the city and will open up private sector job opportunities in precinct management. This will open the way for further regenerative and development initiatives. It will increase demand for residential accommodation in the CBD and create additional business opportunities – in restaurants, retail and other services – to meet the needs of people living and working in the city.” The conceptual framework makes specific provision for emerging businesses and small business premises and these will form part of the brief when the project is put out to tender.

In his end of year report for 2003, Gauteng Premier Mbhazima Shilowa mentioned an investment sum of R300 million from the Province for the purchase of buildings and development of the precinct. Although the Department of Transport and Public Works has not committed itself to a timeframe, it is keen to progress the project from concept to implementation.

It is interesting to note that the old Johannesburg Post Office, which faces the City Hall across Rissik Street, is currently being refurbished. There are also, apparently, plans afoot to upgrade Main Street, south of the Government Precinct, from the section between West and Maclaren, earlier pedestrianised and planted by Anglo-American, up to Rissik Street where Main reaches Gandhi Square. The city is alive with possibility!

-----

From plantation to fynbos and forest
Pezula Private Estate, Knysna

The Estate of about 612ha is situated adjacent to the Sparrebosch Estate east of the Heads in the Knysna Municipal area. For the last 60 years, the bulk of the site has been under exotic timber plantations, with only 194ha of natural coastal fynbos and afromontane forest remaining. The 255 erven which will be developed on the Estate, over ten years, will be sized so that about 504ha of the total site will be private open space, with disturbed areas being rehabilitated to original natural vegetation.

The Environmental Impact Assessment (EIA) of Pezula Private Estate was carried out by HilLand Associates and summarised in an Environmental Impact Report which led to a positive Record of Decision (ROD) being issued by the Department of Environmental Affairs and Development Planning (DEADP) in October 2002. Municipal approval was given in November 2002. The Construction and Operational Environmental Management Plans (EMPs), requirements of the ROD, were prepared by Pieter Badenhorst Professional Services.

The team responsible for environmental management at Pezula includes Jessica Hayes who has recently been appointed as environmental manager; while the wildlife management is the responsibility of Dennis Robson; propagation and landscaping falls under Ben Roos who works in conjunction with Richard Seager; and Jaftha de Villiers is the maintenance manager. In keeping with a requirement of the ROD, an Environmental Liaison Committee (ELC) was appointed prior to the start of land clearing to monitor the implementation of the Construction EMP. The committee meets every six weeks and special meetings have been called to deal with unexpected problems. Managing director Peter Rimbault and Jessica Hayes represent Pezula on the ELC.

Renowned environmentalist Dr Allan Heydorn is chairman of the ELC, while DEADP is represented by Dr Steve du Toit, the Knysna Town Council by Councillor Winile Joyi, the Knysna Environmental Forum by Lorna Watt who also represents WESSA, the Noetzie Conservancy Owners Association by environmental lawyer Elbie Burger, the Outeniqualand Trust by Prof Brian Allanson, SANParks by Peet Joubert and the Sparrebosch Home Owners Association by Dick Wooding.    

Botanical consultant Jan Vlok, who is revered in the southern Cape for his in-depth knowledge of the plant communities, has prepared a rehabilitation plan for the Estate. About 400ha are scheduled for phased rehabilitation. Hayes, who has specialised in woodland ecology, is responsible for carrying out the rehabilitation and she maintains that there are no known examples anywhere of such extensive rehabilitation from commercial plantation to coastal fynbos and afromontane forest. The sheer scale of the project makes it the largest of its kind as yet and as a result it is a pilot project, the success of which needs to be carefully monitored as it progresses.

Each erf on the layout plan comprises a demarcated ‘disturbance area’ which will vary in size depending on the size of the property but will be limited to 50% of the site on smaller erven, and only this portion of the erf may undergo any physical disturbance – accommodate the footprint of the house and garden – while the remainder of the property will be rehabilitated back to its natural state and serve as an ecological corridor area. The Estate will also have a sports complex and equestrian centre and the renowned Sparrebosch golf course, now called Pezula golf course, has been bought by Pezula and is a component of the Estate. The so called Field of Dreams will comprise a cricket academy and oval and a tennis academy where less-privileged, promising youngsters will receive training to fit them to compete internationally.

Roos, who is responsible for landscaping management on the Estate, says that based on the recommendations of a workshop and the advice of Vlok, 95% of the plants used in the public landscaped areas and around the houses on the site will be ‘locally indigenous’, the rest will be indigenous to areas slightly further afield, for practical reasons such as lack of availability. The debate at the workshop questioned the meaning of the term locally indigenous – and this is frequently a contentious issue. Roos has established a holding nursery for plants taken from areas where services are being installed. These plants will be returned to the areas they were rescued from. Other plants will be propagated in another site nursery and these will be planted along the roads and in other public areas, where the micro-climate suits the species. Roos comments that he is being guided by Vlok in this process.

Roads and other services are being installed on site and this has required stabilisation and rehabilitation work. The main roads on the Estate follow the routes of the old forestry haul roads and there are only short stretches of new road planned. All cut and fill sections are being stabilised with vegetation. To ensure that the same topsoil with the appropriate seedbank is returned to the exact area it was scraped away from, the topsoil is not being ‘stockpiled’ in the usual sense of the word, as recommended by the EIA, but the process is taken a step further and the soil is pushed up just beyond the embankment while work is in progress and then pulled back down over the denuded area when construction is complete. As Roos says, this not only means the seedbank is retained in the right place but the process requires less labour and transport, and therefore makes good economic sense.

In order to maintain the rural character of the Estate and to minimise stormwater runoff by limiting hard road surfaces, the roads comprise concrete strips with vegetated sides and centre strips to allow stormwater infiltration. Wooden structures, made of gum poles and stabilised with stakes, that serve as water dissipators, have been constructed at all stormwater outlets to guard against erosion. As the water has spread out below these structures, so there has been a good regeneration of hydrophylic species such as sedges and this wetland vegetation acts as a natural filter. Eventually the structures will become completely overgrown. Other erosion control measures include the use of silt screens on the road embankments comprising either shadecloth barriers or onion bags/orange sacks packed with mulch. The latter will not only hold back the silt but will serve as a growth medium encouraging the germination of fynbos and grass seeds.

Power lines and telephone cables are being located underground along the road reserves and street lighting is being limited to low level lighting which creates a washed effect across roads at intersections. No high level lighting is permitted so as to preclude any light pollution on the Estate. Pezula has adopted a dark sky philosophy.

The sewage system will comprise individual biological filter treatment units supplied by Biolytix SA, as recommended by the EIA, which will allow the treated water to be dispensed into low topsoil berms. Aside from the lower capital expenditure, water savings will be achieved and the treated water could be used for garden irrigation purposes.

A botanical garden is planned for the site and it will be 85% representative of the afromontane forest of the southern Cape and its ecotone, while the other 15% will comprise other indigenous species. Open days are planned for the botanical garden, when the public will be encouraged to visit and learn more about the vegetation of the area, while school groups will be able to schedule special visits, comprising lectures and guided tours, along with old age homes and specific interest groups from the community. Roos says that a section in the garden is being designed for those who are visually impaired and this will be based on encounters with the plants through the use of the other senses. 

Proposed rehabilitation plan: adaptive management
It has been about 60 years that the bulk of the Pezula property has been under pines – Pinus pinaster and P. radiata – and some areas of gum – Eucalyptus diversicolor. Under the first generation of pine trees, the indigenous seedbank is still very good but in areas that are under second and third rotations of pines, and particularly gums, the seedbank is less viable. Gum trees make use of allelopathy as an anti-competition mechanism. They release a chemical substance into the soil that acts as a germination or growth inhibitor to other plant species. This chemical eventually leaches out, allowing natural regeneration, but the process is slower than under pines.

The plan for the first two phases of the rehabilitation work, devised by Vlok, will be implemented under the management of Hayes as the pine plantations are being cut down. Largely, areas will be returned to the vegetation type that would have occurred there naturally – either coastal fynbos or afromontane forest or their ecotones. The placement of the residences, however, has had to be taken into account to facilitate management – and forest is easier to manage than fynbos, because it does not require burning. According to Vlok, coastal fynbos in the southern Cape has a burning cycle of between 18-25 years.

Once all the pines in a certain area have been cut down and the timber collected, the harvesting debris will be spread across the area and allowed to dry out for a month or two and then a fire will be put through the carefully demarcated area, as indicated in Vlok’s planned burning regime. Pine stumps will not be removed except in areas that are scheduled for development, where both the stumps and their extensive shallow root systems have to be taken out. The burning is multi-purpose, as the fire will destroy pathogens and help with the regeneration of fynbos. Alien species that regenerate after the fire will be eradicated, largely by hand.

Clearing of the commercial forests is underway and some blocks are scheduled for burning within the first few months of 2004. This will be done strictly according to the requirements of the National Veld and Forest Fire Act of 1998. The fire department and neighbours will be alerted and substantial protective fire belts will be in place. There is fire tending equipment on site.

In areas which are being returned to coastal fynbos, natural regeneration will be allowed to take place. Naturally occurring protea species may be planted into the regenerating fynbos, because their seeds are less liable to germinate when they have been under pines for an extended time. Otherwise, it is believed that most of the coastal fynbos species will come back naturally with time.

In the areas that are being returned to forest, large scale plantings of pioneer species will be done to supplement natural regrowth, approximately six months after the harvesting debris has been burnt. Chrysanthemoides monilifera (Bietou), which is known to come in first naturally after a fire in the southern Cape forests, is an ideal pioneer as it grows rapidly and has good soil stabilising properties. Another pioneer Virgilia oroboides (Keurboom) will be planted out at the same time. These two species will, in true pioneering style, create appropriate micro-climates to allow the regeneration of other forest species. The latter tree, which is a forest edge species, will also be planted as a buffer between development areas and natural forest. Rapanea melanophloeos (Boekenhout) will be planted a little later in the process, as it is one of the first fast growing woody species to come in naturally. These species will be grown to seedling size in nurseries on site from mother stock on the Estate. Hayes says the seed collection is already underway.

Fire will need to be kept out of these regenerating forest areas and the staff will be on constant alert to guard against accidental fires. Water points along the roads and a fire tender, comprising a water tanker on a trailer behind a 4-wheel drive vehicle, will be brought into action to ensure rapid suppression of any fire.

Hayes calls Pezula’s approach to rehabilitation one of adaptive management – the process will be monitored continuously to gauge progress and management adjusted, where necessary, based on the results.

Wildlife management
Careful management to ensure the survival of all faunal species on site during the development stages is of primary importance to the Estate, hence the appointment of experienced wildlife manager Dennis Robson. 

Once the development is complete, consideration will be given to the re-introduction of small herbivores such as bushbuck, common duiker and grysbok. A warning in the Operational EMP points out, however, that the carrying capacity of fynbos is low and present populations of antelope need to be quantified to avoid over-population.

Robson speaks about the importance of a strong policy on pets for the homeowners, saying that this is still in the process of being fine-tuned. It is necessary that those buying into a ‘natural’ estate of this kind respect the wildlife and although pets will be allowed, control is crucial. Dogs are to be kept only in fenced properties within disturbance areas and must be controlled by a leash when taken off the property to prevent them from chasing wild animals. It is possible that only certain areas will be designated for walking dogs. The Operational EMP recommends that all cats be sterilised to prevent interbreeding with the African wildcat.

Robson is creating low disturbance access to the fabulous pristine areas of afromontane forest on the Pezula Estate, through carefully positioned trails in areas of the forest that border on the Sinclair Nature Reserve. The trails take cognisance of vegetation sensitivity and guard against erosion. All the material used in trail construction is natural material from the site. A viewing area has been established overlooking a man-made water hole sited in an already degraded area – previously a depot for debarking gums – on the edge of the forest. Because the viewing site, appropriate for bird watching and animal spotting, is on a ridge, it would naturally have been a fynbos area with some forest fringe species, and it is being rehabilitated to its former status. A mineral lick provides a supplement for the small mammal species of the forest. Bushbuck, bushpig, mongoose, baboon, vervet monkey, wildcat and porcupine are present on site and the spoor of Cape clawless otter, honey badger, leopard and genet have been seen.

At present, the bird count is at about 40 species and Robson says that there is a lovely variety of sunbirds on site, along with uncommon species such as the Grey Cuckooshrike, the Olive Woodpecker which is scarce on the coast, and the Forest and Jackal Buzzards. Fish Eagles and the Knysna Lourie are also present. Bird perches in the form of dead trees have been positioned strategically to encourage the Forest Buzzard which is possibly becoming a threatened species.

Small-scale wood chopping initiative
A small band of four wood choppers from the nearby Dam se Bos area have been chopping wood on the Estate and selling it locally, per bakkie load, for braai wood or firewood. The marketing is being done by the Estate which also provided the necessary chainsaw, and the enterprise, which has been operating since July 2003, has done particularly well over the recent holiday season. The wood comprises branches left over from the harvesting of gums. The idea is to build further capacity and increase the market for the wood, so that the initiative will become sustainable and will eventually be privatised.

-----

Environmental controls at golf course estate
Sparrebosch, Knysna

The Eastern of Knysna’s two Heads has had a long history of management and the 250 ha Sparrebosch Estate site has been no exception. Prior to the development of the estate, the area had been burnt and mowed on a regular basis to promote the grasses required for cattle and sheep farming. This management modified the naturally occurring fynbos and promoted an increase in diversity, specifically of the monocotyledonous species (geophytes and grasses). Much controversy and speculation was, initially, related to the estate and to the stringent environmental controls which were placed on the development as “conditions of approval”.  Preceding the environmental impact regulations (before 1998), an Environmental Impact Assessment of the proposed estate was undertaken by SRK and strict requirements and recommendations were put forward. 

The development area was restricted to the more disturbed and modified parts of the existing farm, while the remaining 60% of the property was retained as a conservation and rehabilitation area for fynbos and forest. The conditions of approval required a construction phase EMP which strictly controlled the activities on site and the phasing of the construction itself. The EMP conditions were included in the contract documentation in order to ensure that the contractors were fully aware of the environmental controls and to allow them to budget for these controls. Throughout the civil and golf course construction period only minimal disturbance was tolerated. No-go areas (no matter how small) were demarcated and could not be disturbed. These acted as refugia (providing safety from unfavourable conditions) within the development area during construction and proved to be valuable islands during the follow-up rehabilitation.

Rehabilitation and erosion control
The civil and golf course construction was phased to ensure that the areas exposed to the elements were limited, at any one time. The rehabilitation plan for the estate was phased to both precede and to follow on after these construction phases. It included an initial demarcation stage where the disturbance areas were indicated on site; development areas were then mowed and the mulch stockpiled in windrows for collection and use during the rehabilitation stage. During phase one, a site nursery was established and all transplantable species from the first construction phase were rescued and relocated to the nursery. In excess of 70 000 plants were moved to the nursery. During later phases, the rescued plants were moved directly into the rehabilitation areas of the preceding phases. The most successful method of transplanting the fynbos plants proved to be by removing entire sods and translocating these directly to the rehabilitation areas.

The top 15cm of topsoil containing all the roots, seeds and dormant bulbs from all disturbance areas (roads, golf course, pipelines) had to be stockpiled for exclusive use during the rehabilitation. Additional topsoil from deeper in the soil profile was stockpiled separately for use on the golf course fairways. This created various logistical problems during the initial phases, as double handling was required – no stockpiling was permitted in the no-go areas, therefore only areas designated

for future disturbance could be used as stockpile sites. This obviously had cost implications for the developer, but these were planned and budgeted for.

Only after the topsoil had been correctly stockpiled could the civil contractors commence with the earthworks, pipe laying, road building, etc. The phasing of the construction process kept the areas of disturbance (at any one time) to the minimum and this reduced the exposure to potential erosion. Despite this, erosion control measures were required around all areas of construction. These included temporary measures such as vegetated berms, silt traps with controlled overflow points, silt screens at outflow points, mulch bags and others. Permanent controls such as vegetated gabions serving as stormwater dissipaters were put in place at all outlets and stormwater detention ponds were positioned in the valleys. Despite the erosion control measures, storm damage during heavy rains was experienced and a strict monitoring system was required to ensure that silt traps were well maintained and regularly emptied and that any silt which had moved beyond the traps was collected by hand. Earthmoving operations were subjected to the same controls relating to stockpiling and double handling was necessary in certain areas.

Golf course irrigation and stormwater management
In a fynbos environment, nutrient enrichment is a potential impact that must be addressed. Fynbos soils are nutrient poor and an increase in the available nutrients will result in a change in the community structure. Certain plants may thrive with additional nutrients, but others will die out. In order to prevent the golf course irrigation water from affecting the adjacent fynbos and fynbos rehabilitation areas, a closed cycle system was required. A subsurface drainage system was installed throughout the golf course within the playing areas – the rough and rehabilitated fynbos are not irrigated. The drainage system leads to a series of sumps and pumps and all irrigation seepage is recycled back to the irrigation dams for re-use. This recycling of water is also an aspect of the water conservation strategy on site. However, one disadvantage is that the fairways have been planted with cool season grasses and this selection requires additional water to keep the grasses cool during summer. The irrigation water is mainly recycled sewage water from the Knysna sewage treatment plant (which the developer is obliged to upgrade), supplemented by borehole water and, when necessary, municipal water.

The system of recycling the irrigation water has to allow for natural stormwater runoff to continue flowing into the natural drainage lines which feed various wetlands and seepage zones; and ultimately the stormwater runs either into the Sparrebos Indigenous Forest (a local nature reserve) or into the streams leading down towards the Knysna Lagoon. In order to monitor this recycling, an initial baseline water quality sample was taken at 14 sample points in and around the site prior to commencement of construction. Full chemical and bacteriological analyses of these samples were done by the CSIR. The water quality monitoring plan produced for the project required that three monthly samples were taken during the construction phase and that six monthly samples are taken during the operational phase, throughout the lifetime of the project. These samples allow for early warning and detection of water quality problems and the results are submitted to the Department of Water Affairs and Forestry. An added benefit of this water quality sampling was that it led to the detection and repair of leaks at the municipal sewage pump stations – leakage which might otherwise have continued unnoticed.

Success of fynbos rehabilitation
The rehabilitation of the fynbos has been a resounding success. The fynbos communities have been monitored using quantitative analysis since pre-construction, and with the removal of the regular burning, mowing and grazing pressures, the fynbos is returning to a more natural state of its succession. Certain areas exist where the fynbos now needs to be managed in order to accommodate a rare species of butterfly and these areas require different management strategies to the pure fynbos management areas. The fynbos areas now extend right up to the development zones, both golf and residential.

On the golf course, all the out of play areas have been rehabilitated to fynbos in order to connect back as linking corridors to the areas of open space fynbos. These linking corridors of fynbos have acted as refuges allowing wildlife to return to the area and they are now havens for local birdlife, reptiles and small mammals. The wetland areas have created support communities of aquatic life and the frog calls echo late into the nights.

The golf course design itself had to be modified to accommodate the various special fynbos and forest features of the site and the first hole is an example of the changes that were required. The design of the original fairway indicated that a small portion of drainage line, as shown on the contour survey, would need to be filled in. Site investigation, however, revealed that this was actually a forest filled valley – one which the golfers now have to play over! These natural and rehabilitated areas of fynbos and forest are often a slight challenge to the less expert golfer and balls hit into out of play areas have to be collected by trained field staff. The total golfing and nature experience, however, far outweighs the odd frustration of a lost ball.

Indigenous gardening
The conditions of approval required that 20% of each erf had to be retained as a natural rehabilitation area or buffer. In these areas only rehabilitation to the original vegetation is permitted, in order to act as a buffer between the homes and the surrounding open space nature areas and golf course. In addition, the gardens (not included in the 20% natural buffer) have to be indigenous gardens, guided by a list of locally occurring species. The reaction of homeowners to these restrictions has been very mixed. Firstly, it has been a challenge to the architects to ensure that they stay away from the fynbos reserve; secondly, it has meant controlling the building contractors, limiting them to the house footprint and retaining the topsoil for the gardens (fynbos loves fynbos topsoil). Thirdly, many of the local nurseries and landscapers had never heard of the species on the list and if they had heard of them, they did not have the variety or stock available. Particularly at the start of development, there were very few books illustrating the species and those that could be found contained only taxonomic and botanical information, not horticultural information. The start of a huge learning curve!

The indigenous garden – there are always those sceptics who say “you cannot enforce the indigenous garden” and “it sounds great in theory but…”. Well..... the residents have not only embraced the concept, but Jane Crowe, one of the first residents, has exceeded even my naïve expectations about fynbos gardens and their promotion. In order to achieve an awareness of both our local flora and the exceptional biodiversity which has yet to grace our gardens, she is about to publish a book illustrating through her paintings, fynbos diversity and garden applicability. This book, with its remarkable illustrations provides insight into how new Sparrebosch residents have embraced the local flora and are promoting it beyond expectations. What I had hoped would result in an increased awareness of our local flora, has been transformed into an example which should be followed by all. Jane has captured the diversity, variety, colour and uniqueness of the flora and has brought it to within the reach of the ordinary home owner and amateur gardener/landscaper. The Cape Flora, the Knysna Flora and now the Sparrebosch Flora is being enjoyed by all.

Social commitments
From a socio-economic perspective, the environmental controls included monitoring the social commitments of the developers. The monthly environmental reports included feeding back information on the numbers of jobs created, training provided, percentage of local labour (from Kynsna only), Southern Cape labour (excluding Knysna) and labour sourced from outside the Southern Cape. Over the duration of the project, the unskilled labour has been maintained at 100% local, while the total job creation during civil and golf course construction averaged out at 77% local to Knysna. A percentage which exceeded the 70% requirement which had been targeted. In addition, the direct contribution to the local economy during the construction phase (including wages and local supplies) exceeded R54-million. Since the civil and golf course construction ended and the operational phase commenced, the continued contribution to the local economy is being felt in the building, hospitality and tourism industries.
Article by Cathy Avierinos, (HilLand Associates, Environmental Management Consultants), Sparrebosch Environmental Control Officer

-----

Future Normal – mainstreaming green building
The ‘Green Building’, Tokai, Cape Town
The ‘Green Building’ at Westlake Business Park in Tokai, Cape Town, was developed to provide rentable office accommodation and, specifically, to demonstrate that the application of green principles in design and construction can become normal in commercial building in the urban environment. Leigh Darroll visited the site and spoke to architect Mike Schroeder about the project.

The Green Building was initiated by Sarah Ward and Mark Borchers of Sustainable Energy Africa (SEA), in collaboration with Mike Schroeder, an architect working with the Development Action Group and familiar with SEA’s SEED (Sustainable Energy, Environment and Development) Programme. Having identified a suitable site of 1 100m2 in the new Westlake Business Park, the clients sought to develop premises that would demonstrate aspects of their work. SEA, AGAMA Energy and Common Ground Consulting, all organisations concerned with energy efficiency, sustainable technology and urban development, have taken occupation of office suites in the building, which was completed in November 2003. Some additional space is available to other tenants with similar or related concerns.

Design approach
A number of key factors were addressed in the planning and design of the building. It was required to provide affordable, commercially viable, flexible, lettable office accommodation. Energy efficiencies were considered in terms of reducing ongoing energy demand in the building, in limiting embodied energy in construction materials and transport to and from site, and in opportunities for generating energy on site from renewable sources and feeding this into the grid. There was also a concern to limit the use of toxic materials, finishes and treatments wherever possible. The client/architect team sought to harness the best information and experience available; the design was intentionally simple to allow for inputs, responses and decisions to be made as building progressed and according to available advice, materials and skills.

Schroeder explains that initially numerous design and construction options were brainstormed. The developers invited others working in related fields – including architect Etienne Bruwer of Greenhaus Architects, Gita Govan of ARG Design and Peter Willis of The Natural Step – to participate in this process.

Financing
Once a preliminary design had been conceived, the client conducted an analysis of phased financing, taking account of all costs, including rates, insurance, taxes and the like, to ensure the feasibility of the project. Sourcing the finance proved challenging. According to Schroeder, the specifications determined by banks for A-grade office space include air-conditioning. The banks approached were wary of claims that passive thermal design would eliminate the need for air-conditioning and introduce the advantage of reduced energy consumption and lower running costs. So, in Schroeder’s words, they made the developers jump through a few extra hoops. Finally, a bank loan was secured for 70% of the trimmed building costs and the bank retained some of the finance to cover the risk that the building was not fully let before construction began. The budget was fixed at R1,8 million.

Passive thermal design
The double-storey building, with a partial basement beneath the southern wing, is constructed on a T-plan. It provides a total lettable area of 700m2, in flexible office modules, with a shared entrance foyer, meeting rooms, kitchens, ablution facilities, parking and other amenities.

Detailed thermal modelling of the different zones of the building was used to optimise its thermal performance. This takes account of variables such as orientation, thermal mass, materials and construction systems, insulation, ventilation, window area and shading, in relation to a changing exterior climate. In place of average temperatures, extreme seasonal temperatures were input to the software program used for the thermal modelling, to predict internal temperatures under such conditions. Actual temperatures experienced in the building in use will be monitored summer and winter and responses implemented where necessary. Provision has been made for supplementary climate control mechanisms to be activated or installed, should the need arise.

Various construction technologies and materials were considered, including rammed earth, sandbag construction and unfired clay bricks. The relative costs and benefits of using forced ventilation, rock stores and solar fans were also investigated. However, the developers chose not to move too far away from familiar construction systems.

Selection of materials
The building is constructed in recycled concrete brick, on concrete strip footings, with minimal reinforced concrete stiffeners to assist longer runs of wall. The bricks were sourced locally, from the closest supplier, in Paarden Eiland.

Concrete pipes, 750mm in diameter, are built in under the ground floor and linked to two vertical chimney ducts to allow the building to be flushed with cool night air – drawing heat out of the thermal mass – if required. Evaporative cooling systems and large fans, which would be able to provide up to ten air changes an hour, have also been investigated by the developers.

The walls are coated inside and out with an environmentally sound finishing treatment that provides a protective membrane while allowing the walls to breathe – so eliminating problems with damp. This too is a locally developed and manufactured product.

Windows are positioned to ensure effective ventilation and to admit natural light to all workspaces. Both light and ventilation can be controlled individually at each workstation. The ratio of window openings to solid brickwork was balanced to optimise thermal performance and the size of window openings was adjusted marginally to match second-hand galvanised steel window frames where they are used. Purpose-made SA pine windows have also been used. Most of the doors and frames are of recycled Oregon pine, teak or meranti, with some new doors in SA pine. Schroeder comments on the difficulties of finding suitable timber windows and doors, saying that new meranti and other rainforest hardwoods are generally not supplied with certificates of sustainable forestry practice and their origin and the sustainability of their harvesting therefore cannot be guaranteed.

Timber treatment is another area of debate in terms of its environmental impacts. Conventional copper-chrome-arsenate (CCA) treatments are considered by many to be harmful to the environment and to people handling the treated timber, as is tributyltin oxide (TBTO), although to a lesser extent. Boron preservatives are environmentally preferable but present a risk of leaching out of the timber where it is exposed to damp conditions. However, according to Schroeder, many contractors, carpenters and joiners are only familiar with CCA or TBTO treated timber and are resistant to using boron treated timber.

As a softwood, compared to the hardwood meranti, SA pine needs to be properly cured after treatment and is expected to swell and shrink with changes in humidity. For this reason, the carpenters refused to use a water-based treatment for the tongue-and-groove flooring and resisted using anything other than CCA treated timber externally. Other timber used in the building is boron treated and a non-toxic linseed-oil-based sealant has been applied for added protection. Although this imposes higher maintenance demands for the first two years, at biannual intervals, thereafter maintenance treatments are required less frequently.

Timber from invasive species – eucalyptus and wattle poles and latte – is used in the balcony and staircase balustrades, and SA pine-framed shading screens are in place on the northwest and northeast facades, to be fitted with latte should this prove necessary to reduce interior temperatures in summer.

A roof structure of curved laminated SA pine roof beams is used on the northern wing of the building, with a 12mm plywood ceiling and aluminium insulation beneath the external cladding of profiled steel sheeting. Roof insulation was identified as a priority and the aluminium product used was specified for its high insulation value. Conventional timber trusses are used on the southern wing, also with plywood ceilings, aluminium insulation and profiled steel roof sheeting.

The roof sheeting is in a light grey colour which suited the palette of the building and met the requirements stipulated in the design guidelines for the business park. It is important to note that in its overall aesthetic expression the building observes its neighbours and these specific guidelines, as set out by the Westlake Property Owners Association. Schroeder makes the point that this is a further aspect of mainstreaming green building – the design and the aesthetic of green building need not be incongruous in an urban context.

As clients and tenants, Ward and Borchers of SEA emphasise that the Green Building is as much about creating a naturally comfortable and inviting working environment as it is about thermal efficiency and green technologies. “We worked at balancing all the issues,” says Ward, “the aesthetics, the volume and light of work spaces and meeting rooms, the outdoor spaces, all form part of our concern with sustainability.” She points to the staircase conceived and installed by artist Andrew Lord – in metal and wood, using recovered Oregon pine stair treads and found steel pipes as balustrade uprights – which introduces another example of the green ‘reduce, reuse, recycle’ principles. Borchers adds that “the mark of the hand” in construction was also seen as important in making a green building.

Green systems and appliances
In addition to reducing demand for energy by eliminating the need for mechanical air-conditioning, the building will be fitted with roof-mounted solar photovoltaic panels which will be connected to the grid. An inverter has been installed so that solar energy fed into the grid from the PV panels will be credited against the building’s electricity account. A separate solar powered water heating system is installed to provide hot water for the kitchens and showers (for those who cycle to work).

A small wind turbine is also to be installed to supplement the renewable energy sourced electricity supply to the building.

A further measure taken to reduce energy consumption is the installation of energy-efficient compact fluorescent lamps to all light fittings.

Water conservation was also considered. Showers are fitted with low-flow shower roses and water-saving toilets are installed. Systems are also in place for grey water from basins and showers to be channelled to the garden and rainwater will be harvested for use in the dry season. Hard surfaces in the landscaping are limited to allow for maximum rainwater drainage on-site. The parking areas, for example, are spread with mulch that was processed from one of the gum trees that had to be felled on the site.

Planting in the outdoor areas, the eastern courtyard and at the entrance to the building will comprise indigenous species that have a low water demand, as well as plants such as fruit trees, vegetables and herbs that will be useful to the tenants.

Schroeder comments that the building called for an integrated design and construction process requiring an ongoing interface between the builders, artisans, material suppliers and the architect, with adjustments made on-site as construction progressed. The outcome – a building which demonstrates that commercial office premises can be energy conscious, environmentally responsible and financially viable – points to a future where green building could become the norm – and currently unconventional systems could become standard.

-----

Rehabilitation in a headwater catchment of an Eastern Cape River
Featherstone Kloof, Grahamstown

The widespread rehabilitation of wetlands that is happening in South Africa at present has two major aims: to improve hydrological functioning and to improve biodiversity. The unprecedented attention that wetlands are receiving has been as a result of three factors. The Working for Water alien clearing work has revealed a number of badly eroded and dehydrated vleis and marshes that were previously veiled by alien trees and this has caused alarm in ecological and environmental management circles. The Mondi (previously Rennies) Wetlands Project has worked hard at raising awareness of the value and importance of this portion of the water resource. The new national Water Act (1998), recognising that the entire water cycle is the resource, has brought wetlands under the same protective legal umbrella as groundwater, rivers and lakes. As a result, it was possible to initiate the rehabilitation of a small, apparently insignificant wetland in the head-waters of a river.

Grahamstown lies on the headwaters of the Kowie River that flows into the sea at Port Alfred. Featherstone Kloof is one of its catchments and is an area of 1 075ha in the eastern extremities of the Suurberg Range, 8km south of Grahamstown. The geology comprises outcrops of Table Mountain Sandstone interleaved with Ecca, Dwyka and Uitenhage group shales. The soils are acidic, sandy and nutrient poor with pockets of clay and shale. The kloof lies east-west, with south facing slopes that receive more rain than the north facing slopes, which are both warmer and drier. It is in the pivotal zone of movement for the 50-mm isohyet, meaning that it may receive rain all year round but the rainfall pattern is bimodal and low (MAP 689, 9mm) and the surface runoff is only about 5%. Temperatures range from an average of 22,62°C in summer to 11,32°C in winter. This marginal climatic situation means that any increase in non-indigenous vegetation like Acacia longifolia (Long-leaved Wattle) will result in a rapid reduction of soil moisture.

The vegetation is equally complex. The hills in the area, especially on the northern slopes, are mainly grassland with some aloes and other dry land plants, while the moist south slopes have forest pockets interspersed with grassy fynbos. The most amazing feature of this small area is the wide range of flowering plants, due not only to the variety of microclimates but also the variety of soil types resulting from its complex geology.

The land-use history of the area has been well documented mainly because Grahamstown has the oldest extant newspaper in the country. It has been an academic research centre since about 1880 and information on the biota is consequently equally rich.

Before European settlers farmed the area (circa:1830), the inhabitants were Khoi San peoples, to which the rock art attests. In 1867 about 5 000 pine and eucalyptus trees were planted in the vicinity because “the hills were too bare”. In 1909 a reduction in streamflow was noted. A nature reserve was founded on the western edge in 1933 and already the encroaching pines were being mentioned in the press. Between 1936 and 1939 the municipality started the control of hakea, eucalyptus and pines and again in 1945 hakea clearing was undertaken. During the 1970’s ongoing clearing along the mountain drive kept A. longifolia under control and in 1986 Moran and Hoffman released the galling wasp Trichologaster in the area (see UGF Sep/Oct 2003, page 20). This tiny wasp reduces the number of seeds produced by each tree and in so doing reduces the size of the seedbank.

Exotic plants recorded in Featherstone Kloof in 1997 included Long-leaved Wattle (Acacia longifolia), Black Wattle (Acacia mearnsii), Port Jackson Willow (Acacia saligna), various pines (Pinus spp.) and blue gums (Eucalyptus spp.), Sweet Hakea (Hakea sericea), Sweet Prickly Pear (Opuntia ficus-indica), Bug-weed (Solanum mauritianum), Lantana (Lantana camara), Castor-oil plant (Ricinus communis) and the American Bramble (Rubus spp).

The rehabilitation process
In 1997, the Grahamstown commonage was selected as a suitable clearing area for the Working for Water alien clearing programme, as not only was the invasion dense and extensive but the area had been recognised as a node of poverty. Mapping of the stands of invasive plants showed that 48,5% of the area was high density and 39,5% medium density, while 12% of the area was sparsely invaded.

The programme commenced with clear felling of the stands of alien trees from the top (western) section, followed by burning of the first regrowth by municipal staff, while the second and third regrowth was sprayed with herbicide. Clearing of the eastern perimeter of the valley is still underway and extensive follow-up is still required, although regrowth at this stage is sparse in most areas and indigenous vegetation has re-established itself extensively. In addition, extensive sowing and planting of grass, indigenous trees and shrubs was undertaken on the slopes and the valley floor.

After the first clearing, investigation of the valley revealed a gully that started in the forest pocket at the head, running slightly off-centre along the valley floor. Portions of the gully were well vegetated and appeared to be quite old, while in other areas the erosion appeared to be current and active. The combination of dense stands of alien trees on sandy wetland soils had exacerbated the situation by lowering the groundwater table through evapo-transpiration. As soon as the trees were removed from the slopes, the wetness of the ground improved, the amount of water seeping from the lateral tributaries increased and some places along the gully that had appeared stable started eroding actively. Six monitoring sites were selected in the valley and monitoring is done on an annual or bi-annual basis.

A number of professionals were invited to contribute to the planning of a possible erosion rehabilitation scheme. The methods discussed included the construction of stone or brick packed gabions or hay bales, or of sloping the headcuts and employing a geotextile to stabilise the exposed faces, and the using of reno mattresses or broken brick as energy absorbers below the structures.

The positioning of the interventions was decided on by looking at the erosion history and deciding which was natural erosion and which induced. In the end, the choice of method was shaped by the fact that the discharge in the area was not very high and the valley floor was already fairly well vegetated, thus reducing the velocity of stormwater. Other factors considered were methods that would cause the least disturbance, the amount of natural stone in the immediate vicinity and, of course, budgetary constraints.

Sites selected and mitigation measures used
Echo Bowl headcut, Site 3: this area is located a short distance past the terminal end of the erosion gully, which exits the upper forest pocket, known as Buchawe’s Wood. This was the area of the most intense erosion activity and the headcut deemed most in need of attention by all the consultants. The headcut was 1, 5m high and 2m wide at the face extending to about 4m at the bottom end of the active area, 6m from the face.

The headcut was sloped and shaved to a gradient of 1:2, taking care not to allow infilling at the base. A trench was dug around the upper edge of the slope face. A geotextile was secured to iron stakes in the trench with wire extending from stake to stake, and then again by means of iron stakes to the slope. Sods of wetland vegetation were laid over the geotextile, secured with wire netting and bent droppers were hammered in to hold the structure in place. To allow for energy dissipation, the streambed was ‘paved’ with bricks which were secured by wire netting. At the widening of the headcut downstream, a hay bale gabion of about 12m in width was staked across the streambed. The lateral banks of the gully were not sloped or vegetated, nor were they covered by a geotextile.

Results – year one: silting up of the bales started almost immediately due to the upstream disturbance. Vegetation appeared rapidly. The ‘paving’ shifted somewhat after the first heavy rain and more bricks were brought in and the wire netting secured. The general wetness of the area improved. The slope face was still quite bare. At the end of this year, we posed several questions. Were the vegetation sods going to produce growth? The lateral banks below the slope face, that were untouched, looked unstable – should we have sloped these as well?

Results – year two: the vegetation in the area reached head height. The slope was still not quite covered but some plants were present. The streambed was well vegetated but the banks were still bare. Port Jackson saplings were prevalent and these were later cleared out. Indigenous species that had been planted became established.

Results – year three: the whole area was densely vegetated and the site was quite difficult to find. The hay bales were gone but the stakes indicated their previous position. Small patches of geotextile could be found on the upper edges of the slope. The banks had not collapsed and were quite well vegetated. The question that needs to be posed is: how well will the site withstand the first drought and subsequent flood?

Erosion suite, Site 4: this is a hand shaped eroded area of 100m wide and stretching about 750m above the bridge, with numerous small headcuts. The small bridge with 2 x 75cm diameter pipes had previously been built across the ford below the erosion suite. The bridge caused increased water velocity during storms, as the two pipes were insufficient for the discharge and the downstream disperser was hopelessly inadequate. The largest headcut was about 2m deep and 3m wide. All the other smaller headcuts were between 0,5 and 1m deep. The area upstream was reasonably well vegetated with wetland plants and grass on the drier slopes. The foot of the largest headcut was stabilised by staking hay bales across the channel immediately after it narrowed and then filling the area upstream with broken bricks. The bricks trapped the soil produced by the sloping of the lateral edges of the face. Bales were forced into all the narrow gullies and staked down. Some bricks were placed across the face of these gullies.

Results – years one and two: these were wet years with several floods. The edges of the narrow gullies where the bales had been jammed in were eroded as the water found an easier route, but the bales were vegetated. The large headcut had recovered very well, the edges were well vegetated and the bricks barely visible.

Results – year three: the bales disappeared. The whole area was well vegetated but the narrow gullies needed further attention. The bridge was severely damaged by floods.

Reedbed headcut, Site 5: The headcut was a short distance below the bridge, above the first section of healthy riparian thicket. The depth was 2m, the width 1, 75m at the face. The headcut appeared to be cutting back very slowly into a stand of reeds (Phragmites and Scirpus sp.). Most consultants thought that it appeared to be fairly stable, as the edges were well vegetated. It was decided to interfere only minimally and the construction of a stone gabion across the full width of the channel and the floodplain would have been a very expensive exercise. The channel became steeper below the wetland and reached bedrock within 50m. Because the volume of water reaching this headcut was more than at Site 3, the hay bales were keyed into the base of the channel as well as the sides of the channel. An area of about 2 x 1,2m was created and filled with bricks.

Results – year one and two: the floods that were experienced did not activate the headcut. The force of the water moved the bricks away from the face of the headcut but not over the hay bales. The gabion held very well. Natural vegetation became more prevalent but there were still large patches of bare earth.

Results – year three: the area became so densely vegetated that the streambed could not be seen but only heard. When the remnants of the bales were found, they had virtually disappeared under a thick mat of vegetation. At this site the extent of surface wetness had spread laterally and wetland plants were lush, whereas before the area had been occupied mainly by facultative plants such as the Wild Pomegranate – Burchellia bubalina.

Soft gabions
Hay bales wrapped in wire netting and tied together for required length and depth.

Staked across the gully foot, they are best when they are keyed in. Hay bale gabions are used as sediment traps across small gullies. When they are keyed in they effectively stop erosion, trapping sediment that is then stabilised and bound by the vegetation. Where they are not keyed in, erosion starts around the edges where water takes an easier route. Bricks need to be packed upstream of soft gabions to absorb water energy and form a solid basis for vegetation growth.

Suggestions and warnings
If broken bricks are obtainable from a local brickfield, they make excellent fillings and form a sound base for seep and streambed vegetation. Beware of importing bricks from outside the immediate area as this may import alien soil types. Metal oil drums cut in half lengthways make excellent carriers for bricks or soil. We soldered metal pipes along the long edges and two people could cart a substantial load over uneven ground. If banks are sloped, it is important to vegetate these. Leave the site for at least a year before planting other vegetation; it may revegetate without assistance.