Effect of harvesting and cleaning on nutrition in Chinese fir plantation
不同收获与清林方式对杉木林养分的影响

The trasferrence of nutrient elements caused by three different harvesting systems of complete tree harvesting,whole tree harvesting and conventional harves ting under the third rotational stand of Chinese fir were compared in this paper.The result indicated that the loss of nutrient elements due to complete tree and whole tree harvesting was 1 99 and 1 64 times that of due to conventional harvesting,respectively.Slash burning resulted in great loss of N and P2O5 in forest ecosystem.The loss of N and P2O5 from stands due to adopting conventional silvicultural system (harvesting and following burning) was both higher than that of whole tree and complete tree harvesting without burning.Thus,shortening rotation length may cause serious deficiency of site N and P2O5 on site.Complete tree and whole tree harvesting can cause substantial base ion removal from the stand and resulted in seriously soil acidification.