In this paper, a newnet primary productivity model of natural vegetation is presented, with a view to the ecophysiological feature and regional evapotranspiration model relating the two well-known balance equations on the earth′s surface: water balance equation and heat balance equation:This model will help us to study the potential productivity of zonal landscape, the regional and global distribution of NPP, to predict the possible impact of global change on terrestrial ecosystems, and to make good use of climatic resources.

Based on the data of rainfall, throughfall, stemflow in four consecutive years (1989—1992) , redistribution of rainfall, chemical influence of canopy on rainfall and effect of canopy on decreasing potential energy of rainfall were analysed in the regenerative tropical mountain rainforest ecosystem at Jianfengling, Hainan province.

By means of calorimetry measurement, the caloric value (CV), the standing crop of energy (SCE), the net energy production (NEP) and energy conversing efficiency (ECE) of total radiation in vascular aquatic macrophyte (VAM)communities were determined and discussed. The results showed that (1) The average CV of the VAM was 15.39 kJ/gDM, the CV in stems and leaves was generally higher than in roots; and the CV of emerged plants> CV of floating plants > CV of submerged plants. (2) The CV of the floating plant communities were similar to that of emerged ones, and both were bigger than that of submerged ones. (3) The SCE was the highest in emerged plant communities, and the lowest in floating ones, while the submerged communities had a intermediate SCE. The vertical allocation of the SCE accumulated in the submerged communities could be divided into three types. (4) The ECE of total solar radiation by VAM communities was 0.54% in average, among which the ECE of Phragmites communis community was the highest (2.09%)and the average ECE of submerged communities was 0.26%.

The mineralization of soil microbial N, P and K varied withvegetation types, ranging from 20.24—33.36, 2.01—3.86 and 8.88--18.35mgkg dry soil, respectively.The amount of nitrogen mineralized from soil microbes wasclosely related to the biomass-C. The regression equation was y = 0.3761x+ 4.8455,r = 0.5519***(n = 60).The total C, N, P and K in soil microbial pool were 702.94—1150.58, 93.72—155.53, 10.95—20.27 and 34.03—70.35 kg·ha-1 the average values were 924.15+195.73, 117.27 + 25.52, 15.08+3.95 and 50.14+13.29 kg·ha-1 accounting for 3.00 + 1.13, 5.34 + 1.57,1.71+0.57 and 0.26 + 0.22% of the total soil C, N, P and K.The status of soil microbial pool nutrient in monsoon evergreen broadleaf forest was better compared with other vegetation types.

An investigation on the community structure and biomass dynamics of the Kobresia pygmea community was carried our mainly in a plot of 30m×30m, at the Haibei Research Station of Alpine Meadow Ecosystem from May to September in 1989. 35 species belonging to 30 genera and 11 families were recorded. Besides the first dominant species Kobresia pygmaea, the dominant species also included Stipa aliana, Saussurea superba and Festuca rubra, etc.. The 65.7% of the species were hemicryptophytes, and the other 34.3% were geophytes. The vertical distribution of both above and below ground biomass of the community showed a pyramidic pattern. The 91.8% of the above ground biomass and 90.4% of the below ground biomass were respectively concentrated in the 0—10cm layers above and below the ground.The seasonal biomass dynamic (Wi) of the different plant groups could be described by Logistic equations: Wi=Ki/[1 +exp (Ai-Bi·t)]; where t referred to growing days since the 21st April, Ki referred to the maximum biomass, i referred to different plant groups, Ai and Bi were constants. While the seasonal changes of the litter biomass showed a V-curve, i.e. the litter biomass was the lowest in Summer.The growing rates of different plant groups were different, but average growing rate of the community biomass was 2.79g/m2·d-1 in the growing season, and the net production of the community was 368.4g/m2·d-1 corresponding to an assimilated solar energy of 6655.16kJ/m2· a-1 among which the sedges, grasses, forbs and litter occupied 35.19%,23.33%,34.15% and 7.42% respectively.

1. The average concentration of P in the tissues of the 14 crops of the Haihe River Basin was 0.127%, varying from 0.023% to 0.214%. The highest P concentration in different organs of the 14 crops was 0.419%, while the lowest was 0.019%.2. Of the 14 crops in the Haihe River Basin, Panicum miliaceum had the highest P output (removal in the harvested parts) from the soil pool, being 99.758±56.935kg·ha-1·a-1 followed by Zea mays and Gossypium hirsutum. Ipomoea batatas could be considered to be the greatest P contributor to the soil pool (the returning rate averaging 12.557kg·ha-1·a-1, but including the edible parts), followed by Zea mays and Arachis hypogaea. Most of the other crops contributed a very small amount of P to the soil, generally less than 2 kg·ha-1·a-1.3. The fruits of Zea mays, Panicum miliaceum, Arachis hypogaea, Gossypium hirsutum and some others, and the stems or stems plus leaves of Zea mays, Arachis hypogaea and Ipomoea batatas and so on were the main P output carriers. The low P input rates of most crops grown in the Haihe River Basin suggested that a largeamount of P was removed with the harvested parts.4. The P outputs in the corn fields of different subsidiary river basins of the Haihe River Basin were different, in the order. Daqing River Basin> Chaobai River Basin>Zhangwei River Basin>Haotuo River Basin>Yongding River Basin.5. Our results show that the P removal by harvested crop parts was 22 times of the P returned, suggesting that if the straw was not returned, growing Panicum miliaceum, Zea mays and Gossypium hirsutum would result in P losses of 99.758, 32.661 and 26.591 kg·ha-1·a-1 respectively. To maintain the soil fertility, P fertilization or returning straw to the field are recommended. The farmers, however, have only paid attention to P fertilization, but have ignored the straw-returning method that is considered to be a very effective way to recycle not only P, but also other essential elements as well.

Littledalea racemosa is one of the endemic grass species distributed only in the Qinghai-Xizang Plateau, and mainly within the alpine belt between 4400—4900m above sea level. The distribution area of the alpine steppe dominated or co-dominated by L. racemosa is delineated by the Kunlun Mountains in the north, the Tuotuohe river in the south, and the Hoh xil Mountains in the west. The steppe community is relatively poor in species, only 34 species being recorded in the 8 investigated plots. The 61.8% of the species are of Qinghai-Xizang Plateau geographic elements, and more than half (also 61.8%) of species belongs to the hemicryptophytes. Most of species are perennial with exceptions of 2 prostrate shrubs and I annual. Based on the species composition and structure of the investigated communities, at least 4 community-types of the alpine steppe were distinguished. they were the L. racemosa dominated steppe, the L. racemosa and Carex moorcroftii co-dominated steppe, the L. racemosa and Astragalus confertus (A. polycladus) co-dominated steppe, and the L. racemosa and Stipa purpurea co-dominated steppe. The difference of soil texture and structure were the principal reason for formation of these community-types.

Alhagi sparsifolia is widely distributed in lowland saline meadows of Xinjiang desert region. It occurs as a dominant or an accompanying species in plant communities. In saline meadows, the floristic composition and the population character of A.sparsifolia varies with the changes in soil water and salt conditions. Under the influences of human activities, more serious changes happen upon soil water and salt conditions. As a consequence, the floristic composition of saline meadows become unstable. The population character of A. sparsifolia may be used as an indicator for succession state of plant community. This function is of significance to water and land use in that region.

The accumulation ratio of element in trees, that is the ratio of the element content in trees to that in the soils (T/S), was used to analyze the accumulation characteristics of elements in the tree-soil system in mining area of Xixia mountain, Nanjing. The results showed that the content of K, Ca and P had little relations with the tree species, or human mining activities. Different tree species had the largest T/S for different elements. For example Pinus thunbergli for Cr and Alp P. massoniana for Mn,Pb, Co and Ni; Pterocarya stenoptera for P; Robinia pseudoacacia for Cu. The age of Pinus thunbergli had some influence on the content of Co, K and Zn, and the T/S of Ca. There was a positive correlation between the T/S curves of Co and Ni, and of Sr and Ba; indicating a geochemical conjugation of these two pairs of elements.

The Gongga Mountain is located on the southeast edge of the Qinghai- Xizang (Tibet) Plateau and is in the middle of the Great Snowy Mountain Range of the Hengduan Mountain System, with its main peak being 7 556m above the sea level. Picea brachytyla mainly distributes on the east slope and its distributional range of altitude is between 2 300m to 2 800m.We used five methods to study the spatial pattern of different communities dominant by Picea (brachytyla. The results show that most of the species were of clumped distribution type. However, the edificator, Picea brachytyla, was of the random distribution type. Our studies on the spatial pattern of trees in different sublayers and the Morisita Index using plots of varying sizes have revealed that the spatial pattern changes as the community develops, and is influenced by the formation of microhabitats, such as tree gaps. The factors responsible for the dynamic changes of the spatial pattern with forest age include self-thinning and alien-thinning caused by intra- and interspecific competitions in the community.The association coefficients and a 2× 2 contingency table were used for the measurement of interspecific association. Based on the semi-matrix diagram of 62 tree species, we divided them into four closely linked natural groupsm of which two groups are very clear,one is suitable for higher altitude, and one has been invaded by broadleaf trees.The combination of spatial pattern analysis with interspecific association measurement may be one of the approaches to explain the distributional range of species, population structure, community succession, as well as the diference in their habitats.

The woody flora, forest types and dynamics as well as the climate and soil characteristics in Nanking were synthesized. The 282 woody species, belonging to 143 genera and 53 families, were recorded, among which there were only 5 evergreen broad-leaved trees and 11 evergreen broad-leaved shrubs. The forest could be classified into 9 formations, i. e. ,Form. Liquidambar formosana, Form. Quercus variabilis, Form. Q. fabri, Form. Q. acutissima, Form. Q. dalbergia, Form. Robinia pseudoacacia, Form. Pteroceltis tatarinowii, Form. Pinus massoniana and Form. Pinus thunbergii. The analysis of the vegetation dynamic showed that the forest in Lin-Guo-Shi (Temple of the spirit Valley)developed toward the Liquidambar formosana-Quercus fabri-Q. variabilis forest; the forest in Qixia Mountain, toward the L. formasana-Q. variabilis Tilia forest; while the forest in Lanya Mountain, toward the Pteroceltis-Zelkova-Platycarya-Acer-Paliurus forest.It is much more colder in Winter in Nanking than in Hanzhong and Ankang, the northernmost distribution area of the evergreen and deciduous broad-leaved mixed forest. The low temperature in Winter could be the main factor limiting the growth of the evergreen broad-leaved trees in Nanjing. The present zonal vegetation in Nanjing should belong to the deciduous broad-leaved forest.

Twenty permanent quadrates of 50 x 10m2 in evergreen broad-leaved forest in Simian Mountain of Sichuan Province were ordinated according to the important values of the dominant tree species using the techniques of principal component analysis (PCA), detrended principal component (DPC) and nonmetric multidimensional scaling (NMDS). The results of PCA demonstrated a nonlinear relations existing in the data; and a further analysis of DPC confirmed the existence of the strong nonlinear relations. While the results of NMDS clearly revealed the relationship between dominant species and environmental factors; which provided a fundamental base for further study on the secondary succession of the forests in the permanent site.