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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