The paper has made assessement on changes of some soil microorganism groups during the process of forest rehabilitation after shifting cultivation and after clear cutting in Song Ma district, Son La province. Sampling has been made in forest areas naturally regenerated for 4-6; 9-11; 14-16 and above 20 years after shifting cultivation and after clear cutting. The results have shown that the total aerobic bacteria, the total actinomycetes and the total microfungi have increased from the rehabilitation stage of 4-6 years (3.12x102; 1.23xl03and 8.05x102 CFU/g respectively in forest areas after shifting cultivation and 4.25xI04; 2.32x103 and 7.32x103CFU/g respectively in forest areas after clear cutting) to the rehabilitation stage of~ 20 years (3.54xl05; 2.23x104 and 2.51xl04 CFU/g respectively in forest areas after shifting cultivation and 4.35x106; 2.72 x 105 and 5.46x105 CFU/g respectively in forest areas after clear cutting). The capacity in free nitrogen fixation, in cellulose decomposition, in phosphates decomposition, and in polysaccharide production of the aerobic bacteria, of actinomycetes, and of microfungi is lowest during the first forest rehabilitation stage (4-6 years), then it grows and reaches the highest value during the stage of or = 20 years (5.60x103; 2.75x104; 2.l0x103; l.36x104 CFU/g respectively in forest areas after shifting cultivation and 5.24x103; 3.14x 105; 4.27xl04; 5.39x 104 CFU/g respectively in forest areas after clear cutting).
Lọc theo danh mục
Lượt truy cập :
30,060,625
Xem toàn văn