| The Controversial Issue Of Alien Organisms |
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by Patrick Dowling
The issue of alien organisms and their impact on the biodiversity and environmental integrity of host countries is a global concern the specifics of which include loss of indigenous species, erosion, water resource depletion, fire hazards and threats to local economies.
It is the sense of such threats that drive authorities and agencies to actions that can often appear excessive. The clearing of pine and gum trees on the Cape Peninsula is a case in point. Most of these trees started off as smallish plantations to cope with local timber demand and compensate for the earlier denuding of the indigenous forests of Hout Bay and Newlands by colonial decision makers.
Experiencing what is known in conservation circles as ecological release, the absence of natural pests, predators, fungi and diseases that limit nearly all indigenous species on their home turf, the plantations soon started producing many escapees that spread into areas where they had not been planted. Vigorous growers using major supplies of scarce water and crowding out the mountain fynbos these trees, complemented by their invasive acacia fellowa, Rooikrans and Port Jackson in the lower, sandier coastal regions, these plants soon started taking over large parts of the Cape Town landscape. The same was happening in other parts of South Africa which is now facing the challenge of a total invasive alien plant siege equivalent to the area of Britain some 36 million hectares.
Most of the invasive species including birds, animals, fish, crabs were introduced deliberately or accidentally by people over the last 300 hundred years or so. Very few have been transported by wind and currents to our shores. The rapidity of this influx has meant that there has been no time for gradual ecosystem evolution as is the case with natural global changes and so the little understood threat to biodiversity has been considerable with massive regional variety being steadily replaced with monocultures.
Not all aspects of the aliens species is bad which is what leads to their passionate defence by many. Gums, pines and oaks provide shade and cool, sometimes attractive environments that look green and natural. In our short lifetime perspectives they seem to have been there forever.
Where it could be said authorities like National Parks, Cape nature and local authorities have erred in response to alien invasive control is the apparently ad hoc approach adopted. Suddenly the public sees a bare, ugly area of several hectares where there used to be "lovely trees providing shelter for birds and recreational space for people". This is resented and resisted - a pity when proper communication could have ensured public buy-in, alternative plantings, informative signage, set aside recreational areas and so on.
Nevertheless tackling the threat of invasive species remains a high global environmental priority topped only by climate change and GMOs. People migrations, refugees and squatters, sometimes also referred to as alien invasion, has more to do with politics and economics than the biodiversity challenge.
Patrick Dowling
Planning & Environment portfolios
Kommetjie Ratepayers and Residents' Association (KRRA)
Ph +27 (0) 21 783-2509
Ph +27 (0) 21 701-1397 (w)
cell: +27 (0) 84 966-1249
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 Source: News Dec 2006 - Jan 2007
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