Dear Philip, Sustainability is a question of values. Which values humans choose to sustain is both subjective and arbitrary. As such, it should be known that is practically impossible to sustain all values as often we face tradeoffs. A conformable compromise is often what we strive for; a balance between economy, ecology, and other spiritual values. Some people believe that we should fragment the landscape an dedicate pieces of land for different values, rather then seeking a balance for every location.
I suspect that the grass landscape in your region is maintained by fire, rather then being a true climax. As such, fire disturbance prevents tree seedlings from establishing and growing to maturity. Thus, removing fire is a 'human disturbance' that can be useful for establishing and maintaining a forest cover, but prone to cause long-term ecological unbalances. Such is the case when fire is removed and insect populations rise to epidemic levels. Forest monocultures aren't wrong per say. Nature often functions this way, as some species are better adapted for certain environments than others. Species exclusion, or extreme lethal vegetation competition, is a natural mechanism. What's not so natural is when an alien species is being established in an environment that cannot handle its presence. This might be the case in your region since the plantations are lifeless, and lead to problems such as 'green deserts', 'green cancer' and 'ecological wastelands'. Whether or not the soil will modify itself, due to the presence of trees and removal of fire disturbance, and become a productive medium is questionable. It depends. Yes, you are right in affirming that the soil will have more fungi; basidiomycetes. These forest fungi grow well with wood substrates (see the BDNow discussions on wood chips). The question of biodiversity is difficult. If the forester has good knowledge in site restoration and soil health, then biodiversity might stay the same; lost species will be replaced by new ones. Could it be that your region was once a forest and latter transformed into a grassland because of climate change and human impact? This is the case for many deserts in the world. And... there are now holistic techniques for bringing back 'natural forests' to these areas, if this is the values that people want. Personally, I would first ask myself which tree species could grow naturally in that location, rather then force alien species. I'm sure that if you go for a walk-about and observe the landscape you'll find the answer. Then, I would learn more about the reproductive nature of these tree species. It could well be that they need shrubs and other organisms to help them regenerate properly. Anyway... this is just a reflection of my personal value system. As the visiting scientist if they plan to chemically fertilize the plantation, or if they have a management plan for insect infestations, or how they will prevent fire from burning the forest. Also, why they are not interested in reclaiming the sites with natural tree species. Is it that they have already established a wood market, or that they don't know what the hell they are doing? And finally, what is the set of values that they want to sustain (jobs, $$$,...)? Philip, what do you do in Africa? Are you farming land? ( I'm a forest ecologist in Canada) Cheers, Robin ----- Original Message ----- From: "Philip Owen" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: 13 octobre, 2002 04:05 Subject: Industrial Timber Plantations - Sustainable? > Dear BDNow > > Here in Mpumalanga Escarment, South Africa, most of the original climax > grasslands have been planted to industrial monoculture pine and > eucalyptus plantations. Both these species are alien to the region. > These alien timber plantations are the "mother of all monocultures", > with drastic impacts on biodiversity and vital functions performed by > the original integrated natural environment. > > Conditions in the understory of these plantations are lifeless, leading > to terms such as 'green deserts', 'green cancer' and 'ecological > wastelands' beieng applied. As I understand grasslands are bacterially > dominated, and forests dominated by fungi. As these grasslands locally > are being replaced by 'false forests' the soil landscape is becoming > fungal dominated. > At an upcoming meeting scientists associated with the industry will > argue that this implies the soil will become progressively better for > growing timber, and that soil nutrient quality in timber stands are > actually improving for tree growing...??? > > How can this be true? > > Surely the fact that it is a mono culture with extremely limited > biodiversity and ecological interactions dooms it to medium / long term > soil nutrient depletion? > > Your comments will be much appreciated. > > Philip Owen > www.geasphere.co.za <http://www.geasphere.co.za/> > > >
