At 12:56 4/11/97 +1300, Neil Eggleston wrote: >My observations on Masson Pine in southern China support that successive >high grading has put negative genetic selection pressure (postings from >Stewart Cameron and Ryde James). I hope that Chinese foresters are now >able to make use of the internet, as their input would obviously be the >most valuable in this discussion, but last I heard their access was very >limited, so I will offer mine. > >A couple of years ago I was part of a team involved in a resource >assessment project in Guangxi province. We got to see what were >virtually virgin stands of Masson Pine in isolated areas in the >mountains. The vigour and form of the trees in the less distrubed >forest was far superior to that found in the plantations and the >disturbed natural forest occuring close to human populations (sorry that >data and photographs not available). > >Part of the loss in vigour in the lowland stands would have been due to >site differences, with some stands appearing to have been established on >soils which had been abandoned for food cropping after centuries of >cultivation had reduced soil fertility to low levels. Nutrient removal >through the collection of fallen pine needles and small branches being >broken off for firewood would also have contributed to reduced growth >rates long term. I suspect that growth would also have been affected by >the widespread practice of tapping Masson Pine for resin. Harvesting of >trees under a certain diameter was prohibited, and resin collection was >also restricted to the larger trees. Once resin tapping of a tree began >it is likely that growth was slowed and fungal infection could be seen >at the scars which would hasten the decline of the these trees. Once >growth had declined, suitable trees were harvested for sawlogs. > >The net result of high grading and resin tapping was that modified >forest had tended to become composed of slower growing trees of poor >form. I believe that the effect, especially on stem form, was largely >genetic rather than being due to site differences. > >The provincial forestry bureau had recognised the effect of the negative >selection in the past and although they had been strongly encouraged >into establishing southern pines by international agencies, they were >also looking into the potential of tree breeding of Masson Pine, >including the remaining undisturbed populations, as they believed that >the species had undeveloped potential for growth especially later in the >rotation, and inherent suitablility to local conditions. > >Neil Eggleston >Forest Technology Ltd >PO Box 6584 >Wellesley St >Auckland >New Zealand > >ph: +64 (25) 77 94 98 >fax: +64 (9) 445 7739 > >Email: neile@compuserve.com > >
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