Liesbeek Maintenance Project Report
1 May 2011 – 30 July 2011
By: James Cooper (Project Manager)
The River Team
The team have worked 4 days a week during this period due to Grant in Aid funding being secured to clean the banks of the Liesbeek in Observatory. The team consisted of a supervisor and three staff members for this period.
We have found it easier to plan work in four areas during the month, concentrating on one area per week, while continuing with the 2 days of cleaning for the rest of the week.
Litter clean ups
The team continued with weekly cleans from Newlands Swimming Pool to the siding in Rondebosch and cleaning the banks in Observatory. Paradise Park didn’t need to be cleaned as City Parks staff is now cleaning this area regularly.
Grant in Aid report
At the end April 2011 Friends of the Liesbeek were granted R10000 to undertake cleaning of the Liesbeek river banks in Observatory, between the N2 crossing on Liesbeek Parkway and the weir at Station Rd.
Through this funding the Liesbeek maintenance Project has hired 3 staff members, who worked every Friday from 09:00 – 16:00, to undertake these cleaning activities. Additional days were allocated for cleaning when necessary. The staff included a supervisor an experienced river warden who has been on the Maintenance Project team for 2 years and a river warden trainee.
During this period a total of 154 Tuffy bags of litter were collected.
The team has completed weeding all the flowerbeds from Roslyn Park in Rondebosch up to South African Breweries in Newlands.
They continued weeding the planting site before Belmont Bridge and the rehab site behind Newlands Swimming Pool.
Cleaning Alfred stream
Alfred stream has been cleared once a week following heavy rains.
All Kikuyu has been trimmed along the path behind Newlands Swimming Pool. The team continued to maintain the path from Breweries to the railway siding in Mowbray, with the focus on cutting the num num hedges at the Church, Telkom Bridge, Roslyn Rd and Bridge Rd.
The team completed the final section of canal maintenance in Mowbray in front of Rygersdaal Sports Club, trimming all the overhanging vegetation in preparation for winter rains (preventing flooding).
Painting over graffiti
The team completed painting over all the graffiti from San souci Rd to the Railway siding in Mowbray. A watery cement mix was used to paint over the graffiti.
Alien vegetation removal and planting
The team concentrated on a number of invasive alien species during the period, namely Kikuyu grass, Tree of Heaven, Cestrum, Spanish Broom, Purple Loosestrife, Poplars, Canna, Wild Ginger, Eugenia and Crofton weed. On many occasion cleared areas needed to be planted with indigenous plants to prevent soil erosion and to create areas more suited for indigenous Fauna species.
Kikuyu is found along most stretches of the Liesbeek. Control is based around maintaining certain sections where it is either threatening to outcompete and grow over indigenous plants, or encroach into rehabilitation sites. All control of Kikuyu is done by physically digging or hand pulling the plants and roots. No Herbicide has used.
Three sites were focussed on in this period. The first was the Arboretum, below Kirstenbosch. Here one still finds many indigenous plants and a natural ecosystem. The Kikuyu has begun to grow over all of these indigenous plants, smothering them and having serious implications for the biodiversity of the area. The team removed most of the Kikuyu from these plants and in future will be creating buffer zones around the indigenous plant communities, by planting indigenous ground cover plants (Sour fig), which can outcompete Kikuyu.
The second site was the Rehabilitation site behind Newlands Swimming Pool. Here the team continue to remove Kikuyu from the site and have begun creating a buffer zone by planting Sour Fig and Plectranthus around the edges of the site (figure 1).
The third site was the rehabilitation site at Belmont Bridge. Again the team continually remove Kikuyu from the site, and have planted Sour Fig as a buffer. Other plants that were planted in the area included Crysanthemoides, Psorelea, Athanasia and aloes (figure 2). Our Chasmanthyes bulbs that we planted last year are now in full flower at this site.
Tree of Heaven
Tree of Heaven has been identified by the City of Cape Town as a high priority invasive species, which could be eradicated as it is still in the early stages of invasion. The LMP is working in partnership with the City to eradicate this species.
A number of individual Cestrum plants were controlled between San Souci Rd and Riverside Mall. The method used was a cut stump treatment.
Spanish Broom has been identified by the City of Cape Town as a high priority invader species. Only two plants have been found on the Liesbeek thus far. The method used for control was cut stump.
While single Purple Loosestrife plants found along the banks Liesbeek have been easy to control in the past two years, those found as dense stands in Fragmites reed beds have not. Accessing plants through the dense reeds provides one problem and adequately treating them with herbicide, another. To combat this, the LMP team began clearing reeds before the Loosestrife growth seasons (spring and summer), cutting them as low to the ground as possible using a brush cutter, piling the brush on site to prevent seed dispersal. The first section in the Valkenberg Wetlands was cleared in May and monitored closely. The results were very interesting. As we moved to the beginning of July it was noted that the Lythrum had begun to resprout from root stock (figure 3), and that the disturbance and removal of the reeds had enabled thousands of Lythrum seeds to germinate and begin to grow in a concentrated area (figure 4), something we hadn’t seen before.
After consulting with SANBI’s EDRR (Early Detection and Rapid Response) unit and the City of Cape Town’s EDRR the decision was taken to undertake the same process at the remaining two reed beds where Loosestrife has been identified as forming large stands, namely a site at the River Club and a site in Raapenberg Bird Sanctuary. By doing this we are encouraging germination of seeds that could lie dormant for up to 30 years and we are creating easier, more efficient working conditions within the reed beds that will allow for thorough control method. The team are currently working on the River Club section and will complete the initial clearing by mid August.
Research on Lythrum control methods
Research is currently underway to establish the best control methods for Loosestrife. Plants have been grown from seed at a nursery in Stellenbosch and various clearing techniques and herbicides will be tested at three different growth stages; seedlings, saplings and flowering plants. Three 5m by 7 m plots have also been set up in the Valkenberg reed bed to test the effectiveness of the different treatments and herbicides on older, resprouting plants, with a well established tap root system. By the end of this growth season we should have established the optimal clearing technique, which will aid in our attempt to eradicate this invader before it spreads to other wetland systems. Chester, the conservation student conducting the research, was chosen to represent the City of Cape Town at this year’s Fynbos Forum. At the forum he presented a poster (figure 5).
The team concentrated on removal of Poplars around the Valkenberg wetlands, in front of the Wild Fig restaurant. The method used was a cut stump treatment. This was done in the hope that a channel will be dug in order to link the Liesbeek to the surrounding wetlands. This will supply the wetlands with more water during winter, creating many habitats for birds, amphibians and fish, while helping to naturally clean and filter the water. Removal of these Poplars has also taken away the likelihood that vagrants will utilise this area.
A number of Poplars were also removed from the wetlands in Mowbray, using cut stump treatment. All the removed Poplar branches have been used to stabilise the river banks in other sections.
Canna indica and Wild Ginger
The team concentrated on clearing Canna and Ginger behind Newlands Swimming Pool. The South African Breweries staff joined for a day of clearing as part of their corporate investment programme. The banks were stabilised using felled poplar branches and the area has been planted (figure 6)
The following species have been planted in the site:
– Athanasia crithmifolia
– Falkia repens
– Elegra tactorum
– Orphium frutecsens
– Psorelea pinnata
– Pelargonium capitatum
– Ficnia nodosa
It has been extremely encouraging to note the number of Arum lily bulbs that have begun to grow in the areas that the Ginger and Canna were removed.
More and more Eugenia is being seen along the Liesbeek. The luscious red fruits make attractive morsels for birds using the river, and seeds are dispersed far and wide in the bird’s droppings as they frequent other areas along the Liesbeek. The LMP team have cleared a number of Eugenias from San – souci Rr to Riverside Mall using cut stump treatment.
The team have been compiling species lists along the Liesbeek. This has been made possible thanks to a generous donation of field guides from Struik Publishers.
The Liesbeek has been allocated a slot on the Biodiversity database. All our records of flora and fauna will be sent to Westlake where they will be uploaded onto the website.
Enviro centre maintenance
During 2 days of rain the team did maintenance of the Enviro-centre. This included an audit of all the items found in the centre, mopping the floors, vacuuming, weeding the flowerbeds and cutting up Eucalyptus branches and placing around the flowerbeds (figure 7).
The LMP team helped clear paths through the Water Hyacinth found on the Black River in preparation for the annual Peninsula Paddle. The team spent three days clearing the paths, which enabled the paddlers to pass through difficult sections of the river (figure 8).
The team also installed the litter trap across the Black River during this exercise to demonstrate how effectively it works (figure 9)
Ntobeko and Chester were given training on the design of posters using Microsoft Publisher.
All the staff attended the biodiversity expo at Kirstenbosch and thoroughly enjoyed it.
During compilation of species lists the team have discussed various food chains and ecological processes. Each staff member was given a topic to research (an animal found along the Liesbeek) and feedback was done by each member to the rest of the team.
Springing into Life
From July – December each year many exquisite annual geophytes come into flower in the Western Cape. These geophytes lie dormant during the unfavourable dry summer months, but after the winter rains erupt into growth, taking full advantage of the first spring sunshine. They reach flowering maturity and set seed quickly, before other plants can outcompete or shade them, eventually dying back and relying again on their various underground storage organs for food until the next season.
There are many different species of plants which utilise these underground storage organs (geophytes). These organs may differ structurally (bulbs, corms, rhizomes, tubers) but all serve the same purpose of enabling the plant to survive during unfavourable conditions. Many geophytes will only grow after a fire has swept through the area, lying in wait until the correct conditions are experienced. This presents a problem for natural areas situated directly adjacent to urban areas, where fire is considered a hazard, and must be prevented at all costs. One particular species of extreme interest is that of the rare Morea aristata, which is now only found on the grounds of the South African Astronomical Observatory, where a small population has been able to survive the impacts of human activity.
Please note it is illegal to harvest wild flowers from City land or declared Nature reserves, unless the harvester has permission from the land owner. Harvesting of these flowers prevents pollination and seeding from taking place and also removes vital habitats for indigenous fauna species. A prime example of this is the Arum lily frog, which only lives, feeds and breeds in the flowers of the Arum lily.
How can you help?
There are two ways to help save our indigenous geophytes, particularly Arum lilies.
Firstly, please do not buy any flowers from vendors selling them at the robots. If we remove the market for these flowers it will make a massive difference to the survival of the flowers and associated species.
Secondly if you see anyone harvesting flowers or selling them at the robots please contact the City law enforcement on (021) 596 1400/1424.