The biomass and its allocation of a tropical wet seasonal rain forest in Xishuangbanna were studied based on the standard tree regression analysis (for trees and lianas) and clear cut method (for shrub and herb). The total biomass of the community was 360.909t·hm-2,and its allocation in different layers was: tree layer 352.563t·hm-2 (account for 97.69%),shrub layer 4.737t·hm-2(1.31%) ,liana 3.108t·hm-2(0.86%) and herb layer 0.501t·hm-2(0.14%). Most of the biomass of the community concentrated on the tree layer, the organic allocation of the biomass in tree layer was: stem 241.27t·hm-2(68.43%) ,root 69.614t·hm-2(19.75%) ,branch 37.287 (10.57 %) t· hm-2, and leaves 4.392t·hm-2 (1.25 % ); The DBH class allocation of the biomass mainly concentrated on the middle DBH class ,the biomass of six DBH classes from 20cm to 80cm reached 255.460t·hm-2(72.46 %);The vertical allocation of the biomass in tree layer was: the sub-layer Ⅰ 219.365t·hm-2(62.22%),the sub-layer Ⅱ107.743t·hm-2(30.56%), and the sublayer Ⅲ 25.455t·hm-2 (7.22%);There are twenty-six species with biomass over 0.5% of the total biomass of the tree layer, and three species with biomass over 5% ,i.. e. , Pometia tomentosa (account for 19.67% ), Barringtonia macrostachya (5.44% ) and Terminalia myriocarpa (5.27 % ). The species biomass allocation showed that the community had distinct dominant species. The LAI of the tree layer was 5. 724.

The methods in which different of space distribution stands for progress of time and the dimension analyses were used to study the biomass of four different secondary tropical forests in Xishuangbanna. The dynamic on the biomass of secondary tropical forests at the early stages of the secondary succession was analyzed in detail. The results show that the total biomass of four secondary tropical forests increased with the stand age. Total biomass in 5-year-stand, 10-year-stand, 14-year-stand and 22-year-stand were 41.932t· hm-2 , 52.116t·hm-2, 88.284t· hm-2 and 113.743t·hm-2 ,respectively.In the allocation of biomass in different layers in four stands, the biomass of tree layer was over 80% of the total. The biomass of shrub layer increased until 14-year old, then droped down, while the biomass of grass layers decreased and that of inter-layer increased with the stand age.Concerning different parts of plant in the four stands, the biomass of trunk, which occupies over 50% of the total, increased with the stand age, but those of branch, root and leaf decreased. The optimum regression models of different dominant plants and organs of the sample trees of tree layers in the four stands of secondary tropical forest were built.

This study deals with the soil seed bank and seed rain of Mallotus paniculatus forest in Xishuangbanna,Yunnan province. The results show that the soil seed bank had a seed storage of 3345±438 seeds, m-2(Mean±SE, n=20) at the end of rainy season and 4555+554 seed s. m-2 at the end of dry season. The annual seed input was 745 seeds, m-2. The peak of seed input, which caused a high seed storage in soil seed bank ,occurred in dry season. This was in correspondence with the period in which the dominant species dispersed their seeds. The dominant species in seed rain also had a large storage in soil seed bank. The forest fragmentation reduced the seed storage in the soil and seed input and resulted in the significantly high proportion of the seeds of pioneer tree species dispersed by birds in the soil seed bank and seed rain as well. The climax species with seeds dispersed by large animals were not able to reach the isolated forest ,whose succession was retarded.

Scientific planning and rational utilization of land are considered as the most important measure to conserve the existing biodiversity because the loss of biodiversity is mainly caused by land exploitation. Benefiting from diverse climatic conditions, Xishuangbanna is one of the richest area in biodiversity in China. However, due to the increasing of land exploitation ,the biodiversity in this area has been reduced with a considerable speed. The impacts of 8 types of land use on plant biodiversity were analyzed . The order of the 8 types of land use by their intensity of impact on biodiversity was as follows. Monoculture of rubber plantation > Rubber + Tea > Rubber +Pineapple>Home garden>Temple garden>8-year abounded lands after shifting cultivation>Forest+Chinese cardamom>Collective Forest>Nature reserve.

This paper explicitly defines the principles, bases, indices and marks of Chinese vegetation regionalization. Chinese vegetation regionalization system was classified into 4 levels. The super level unit is vegetation biome. The whole country can be subdivided into forest biome, grasslands biome, and desert biome. The primary unit is vegetation region, having 14 ones in China. The secondary unit is vegetation zone and the tertiary unit is vegetation area. The above division scheme has fully absorbed the achievements of previous Chinese vegetation regionalization schemes. The borders of many regionalization units, were modified according to the updated materials.

Quercus Liaotungensis is an important dominant species in the warm temperate zone. In this study ,the leaf demography was implemented with the method of randomized branch sampling. The results showed that 1)The leaf population dynamics was basically similar among individual trees and among different layers of the same individual. The leaf duration and the time in which half of the total leaves fell were very short. The leaf emergence pattern was of flush type; 2) Leaf duration varied greatly among individuals, which can be due to genetic differentiation in the population, but not micro-environment change; 3) Leaf population dynamics coincided with climate change, which was beneficial to carbon gain.

The distribution of soil organic carbon in temperate grassland in Xilinguole, Inner Mongolia was examined. Soil organic carbon content varied considerably among the sites and along soil profile. It increased along the gradient from desert steppe, typical steppe to meadow steppe, while it decreased depth. It distributed mainly in 0～15cm of the top soil layer, The effect of landuse pattern on soil organic carbon content Was also investigated. In the meadow steppe, organic carbon of soil (0～35cm) was seriously affected by the conversion of grasslands to croplands. It decreased by 35%～38%. While in the typical steppe area where grazing management works as primary landuse pattern, it was not affected by grazing intensities in the 17 years.