DECOMPOSITION OF LEAF LITTER IN TROPICAL AND SUBTROPICAL FORESTS OF SOUTHERN CHINA.

In order to examine the effects of global warming on the decomposition of forest leaf litter in Southern China, a reciprocal experiment was designed to decompose forest leaf litter in two sites across climatic zones. One site was located on Mt Jianfengling in the tropical zone and the other, on Mt Dinghushan in the subtropical zone. Both sites were located in NSTEC (North-South Transect in Eastern China), in which the temperature gradient along the transect was the major driver. The two sites had similar altitudes, soil types, annual mean rainfall and dry and wet seasons. The difference of annual mean temperature between sites was 3.7 °C. Leaf litters of 10 native dominant tree species were collected from the two sites and divided into single-species litter and mixed litter, and they were incubated on the forest floor of the two sites reciprocally. The results indicated that litter decomposed in the tropical site 1.36-3.06 times more rapidly than in the subtropical site. Apparent Q10, calculated on the basis of the difference of temperature between sites, ranged from 3.7 to 7.5. The conclusion was that global warming would increase the rate of matter circulation in the subtropical forest ecosystem in China. Mixed litter decomposed more rapidly than single-species litter in subtropical site. Not all dominant species litter could represent mixed litter in decomposition. The variability of decomposition rates among the litter types was less in the tropical site than in the subtropical site. Therefore, the effect of litter quality on litter decomposition was less significant in the warmer conditions of the tropics. [ABSTRACT FROM AUTHOR]