Leaf anatomical structure, photosynthetic enzyme activity, glycollate oxidase activity and stable carbon isotopic composition (δ13C) in leaves from different habitat reed distributed over the Hexi corridor of Gansu province were comparatively investigated. The results indicate that the bundle sheath cells of swamp reed do not contain chloroplasts, the ratio of RUBPcase activity/PEP case activity, activity of glycollate oxidase and δ13C value in leaves of swamp reed fall in ranges typical for C3 photosynthetic plant (wheat). The typical Kranz structure and the bundle sheath cells containning dimorphological chloroplasts were observed in leaves from sand dune reed, the ratio of RUBPcase activity/PEPcase activity, activity of glycollate oxidase and δ13C value are quite similar to that of typical C4 photosynthetic plant(Maize). Salt meadow reed and salt-meadow-sand-dune reed compared with swamp, although there are Kranz structure and bundle sheath cells containning chloroplasts in the former leaves, and the ratio of RUBPcase activity/PEPcase activity in the former leaves are lower than in the latter leaves, activity of glycollate oxidase, especially δ13C values in the former leaves are similar to that of the latter leaves. These results may suggest that, in the Hexi corridor of Gansu province, environmental factors induce an active evolution of the pathway of photosynthetic carbon metabolism within reed species.

Using topographical elevation, pH value and humus content in surface soil as environmental gradient indices, this paper has statistically analyzed field investigation data of forest vegetation in Xunhe River basin and its adjacent area, south aspect of Qinling Mountain, to differentiate forest habitat. 9 habitat types(sites) has been classified in the area by means of principal components analysis (PCA) and discriminant analysis (DA). On the basis of those 9 habitat types, 31 species with environmentally indicative significance have been selected out of all the undergrowth species in quadrats of every type according to species′ present-absent and coverage index. 9 ecological species groups corresponding to 9 types respectively have been established through repeated adjustment process. The indicative amplitude of each group on habitat types has also been reviewed to help distinguish different sites in fieldwork of productional or management parposes.

Analyses of pollen, micro-palaeontology,radiocarbon dating and factor analysis showed that, the evolution of vegetation and geographical environment in the west coast of Bohai Gulf since 25000a. B. P. was influenced by both climatic changes and sea level fluctuation. During the period of 25000—23000 a. B. P. the sea level was high, the vegetation type was forest and grassland. During 23000—12000a. B. P., it was cold and dry, with low sea level and grass-land vegetation type, but grass moor vegetation appeared at the beginning and the end of this period. Period from 12000—5000a. B. P. was a perios of sea level rising and a period of climatic change from cool to warm and humid,with the vegetation of broad-leaves forest and grass or grass swamp. After 5000a. B. P., it became cool and dry. It was a regression period of sea level, with a vegetation succession from grass swamp to salt meadow.

Experiments were conducted in a automaticaly controled climat chamber to study the effect of barnyardgrass shading on soybean nitrogen fixation. Root interference between barnyardgrass and soybean was eliminated by seeding the crop in small pots which were put in big pots and the weed between the small and big pots. The results showed that barnyardgrass at density of 6, 12, and 24 plants/pot significantly reduced the light intensity over soybean plants averagely by 32.1, 39.1 and 43.4% leaf CO2 conductance by 14.0, 16.7 and 19.3%, leaf net phytosynthetic rate by 25.4, 32.7 and 37.3% during the growth season between 43 and 75 days after planting, and resulted in a marked decrease in N2-fixing rate per soybean plant by 31.5, 39.5 and 44.5%, respectively.

The forest dominated by Cyclobalanopsis glauca is one of the main types of the subtropical evergreen broad-leaved forests in China. The studies on the primary productivity of the community have been completed with harvesting method. In this paper, a group of optimized regression biomass models for the tree and subtree layer were reported. The models were also analysed, examined and evaluated. The results showed that there is an allometric growth relationship among the organ variables. It is essential to establish various optimized biomass models using the regression analysis method on the basis of various layers, species and variables. The models are relatively of high accuracy and can effectively predict the biomass of the community. The effective combination of the interspecific models are suitable for subtrees and companion trees. The model differences among species are closely related to their states and function in the community. The distribution ratio of net primary productivity in various organs is the synthetical reflection of the community structure and function in interspecific relationship, niche differentiation and population dynamics.

The plant communities after the 1987′s turbulent forest fire in Amuer forest land of Mt. Daxinganling were studied by using the methods of TWINSPAN polythetic hierarchical divisive classification (TWINSPAN program) and DCA ordination(DECORANA program). By multiple regression analysis to interprete of the DCA ordination axis on permafrost environment factors, we conclude that DCA axis 1 reflects the gradient of soil characteristics and topography which determine the distribution of plant communities; DCA axis 2 is interpreted as the gradient of forest fire intensity, and it can causes changes of the depth to frozen soil and the shallow soil temperature of surface layer which are the significant factors for the distribution of plant communities Furthermore, we used the correlation and regression method in analysing the relationship between DCA axis 2 and permafrost environment factors, and as a result, a regression equation was produced. We also discussed the directions and stages of plant secondary succession under the influence of permafrost environment development based on the results of the above analysies.

The root biomass and the annual root growth of Cryptocarya concinna, Lindera chunk community in Dinghushan Biosphere reserve were investigated by the method of soil columu. The nitrogen concentration of roots was determined by the automaticion analyzer(Quikchem R), and the nitrogen accumulation and dynamics of root pool were also estimated. The results shown that the root biomass(t/h)was 35.43 including live root of 26.63 and dead root 8.8;the annual root growth was 3.74t/h·a; the nitrogen storage in root pool was 279.23 kg/h (202.25 in live pool and 76.98 in dead pool); the annual root growth absorbed and accumulated 57.55 kg/h·a of nitrogen.The ratio of annual root growth and its nitrogen accumulation in total biomass and nitrogen storage of root pool appeared to be higher, they were 10.6 and 20.6 respectively. Therefore, it was considered that the Cryptocarya concinna, Lindera chunii community is in a vigorous stage of growth and development.

The paper presented information of aboveground biomass dynamics of the Festuca extremiorientalis in the Taihang mountain grassland. The data indicate that the aboveground biomass was from 10.80 to 979.30gFW/m2 or from 5.00 to 351.33gDW/m2. The peak value of biomass varied was between 902.87 and 1092.15gFW/m2 or between 331.45 and 370.53gDW/m2.The biomass growth shows a uninodal form. The biomass peak value appear in July. This feature is in accordance with the climate of Taihang mountain characteried by distinct cold and hot seasons, and the corresponding time of hot and raing seasons. The biomass and growth peak shows an obviously positive correlation (R= 0. 8929). The biomass and coverage shows an positive correlation (R= 0.9066). The highest growth rate of biomass and growth high appear at same time. The highest relative growth rate of both appear 30-50 days ahead of their peaks In the growing season, precipitation was the main ecological factor of growth, and the regression equation of both shows y= 6. 2596 +l.4089x(R=0.9250).

The Qinghai Lake region is located in the northeastern of Qinghai-Xizang Plateau, about 36˚15′—38˚20′N,97˚50′—101˚20′E. The elevation of this region is about 3200--5000m about sea level. The vegetation and its distribution in this region was influenced by the existence of Qinghai Lake and the complicated landscape characteristics. Plant species growing in the area is poor. According to preliminary statistics, there are 52 families, 174 genera, 445 species of spermatophytes. The main vegetation types are. needleleaf forest in cold temperate, shrubs in plateau valley, alpine shrubs, sandy shrubs, steppe in temperate, alpine steppe, alpine meadow, swamp meadow, subnival vegetation, and so on. The characteristics of the communities above are described in this paper. The distributional law of vegetation in this region is evident. The horizontal variation of vegetation shows a trend of adapting high-cold habitats from east to west. The temperate steppe, which is distributed in a ring-shaped belt around the lake, is related to the lake basin landscape and the existence of Qinghai Lake. The alpine steppe is found within high-cold habitats. The vertical spectrum in this area from down to up shows steppe-alpine shrubs and alpine meadow-subnival vegetation.As a whole, the region belongs to one part of Qilian Mountains area, and is between the eastern region in Qinghai Province and Qaidam Basin. Based on analysis, vegetation and distribution in Qinghai Lake region has a special pattern and coincides with the climate trends to colder and droughter with the uplift of Qinghai-Xizang Plateau. With all these in mind, we suggest that the Qinghai Lake region, is a relatively independent part of Qilian Mountains area.

This paper presents the research results to detect oil-gas resources by the methods of geobotany and phyto-geochemistry in southeasteastern Junggar Basin. The continental arid climate and temperate desert vetetation is composed of various species of semi-shrubs, small-semi-shrubs, semi-arbors as well as some ephemeral plants in spring. The dominants are Nanophyton erinaceum, Artemisia boroculensis, Reaumuria soongorica, Suaeda physophora and Haloxylon ammodendron, etc.The comporative study revealed that there exists significant difference between the plants in oil-bearing area and the ones in non-oil-bearing areas in terms of growth, morphology, arsh content and chemical composition as well as other related properties.

In the Broadleaved-korean pine forest, the dry weight loss of the leaf of Pinus koreansis, Quercus mongloica, Acer mono., Betula platyphyla, Ulumus propinqua, Tilia amurrensis, and Populus davadiana after 300 days situ decomposition, is 24.2%, 37.6%, 30.8%, 44%, 47%, 50.6% and 55.6% respectively. During the incubation,the dry weight loss has a lineary relationship (R=0.99) with the tested chemical properties of the leavies. In the firest several months, the contents of the lignin and total nitrogen in the leavies are generally increased. In contrast, the water soluable substances are reduced rapitly.Except for basswood leaf, the other leavies can immobolize certain mount of nitrogen until reaching the critical points where the nitrogen content of the pine, oak, elm, birch, aspen, and maple leaf is 0.96%, 1.41%, 2.38%, 1.67%, 1.32%, and 1.32% respectively, From the critical points the leavies begin to release mineralized nitrogen: