STRUCTURE AND ORGANIC-MATTER DYNAMICS OF A HUMAN-IMPACTED PINE FOREST IN A MAB RESERVE OF SUBTROPICAL CHINA

A common practice by rural people in China is to harvest litter and understory from forests to meet their fuel needs. Our study was to determine the impact of this practice, occurring for over 40 yr, on the storages and flows of organic matter in a native pine forest in the Dinghushan Biosphere Reserve. This forest was established to rehabilitate severely degraded lands, and trees were not allowed to be harvested but understory plants and litter were harvested. Despite the initial condition of the site, its relatively young state, and the continued removal of understory plants and litter, there was total of 45 plant species in the study site. The total standing stock of organic matter was 135 Mg ha(-1) with about 60 percent in the trees and 28 percent in the top 10 um of soil Understory and litter, the two components harvested, were about 4 percent of the total standing stock. Total aboveground biomass production was 8.4 Mg ha(-1) yr(-1), with about 45 percent contributed by the understory. The average annual amount of litter and understory harvested (3.3 Mg ha(-1)) was 55 percent of the annual production. Compared with adjacent similar-aged broadleaf and mixed pine-broadleaf forests and other tropical pine forests where organic materials were not harvested, our site had less structural complexity and was cycling organic matter more slowly than its potential. Harvesting the net production of trees, with a replanting program, coupled with litter removal only provided the same quantity of organic matter, but was proposed as a more efficient method of fuel production because it would allow the soil organic matter, soil fertility, and tree regeneration to improve, while at the same time provide a higher quality fuel and reduce the time expended by women in fuel gathering.