Based on the investigation of the vegetation and environment in 119 sites along an itinerary from the desert-steppe transition zone to that of forest-steppe in Inner Mongolia steppe region, the vegetation environment relationships were quantitatively analyzed.The preponderance of the 30 factors in determination of vegetation composition were hierachized according to their sampling quality and their mutual information with the 50 most frequent species. The result showed that climate was the most preponderant; while the topographic and managerial factors were secondary or local. The community composition was well associated with the first dominant species, so the dominance community-type identified according to the first dominant species was the relatively stable unit of similar composition and structure.The ecological vicariance of a large amount of steppe species along climate gradient were revealed by an ordination of these species on a precipitation-temperature plane according to their preference to these 2 factors. This vicariance, especially the vicariance of the dominant species including a group of Stipa species, resulted in the vicariance of the Stipa communities.The traits of the main steppe communities were characterized by presentation of their preference and amplitude on the climate, soil and grazing gradient, and by synthesis of their vegetation features. The direct ordination of the species and communities along the gradients of climate and grazing intensities provided a dynamic scenario of the steppe vegetation under the climate and landuse changes.

The coniferous forest in the subtropical zone of China is suffering from very severe decline. The paper studied the declining pattern of polluted P. massoniana stand in terms of stand characters ,tree growth, physiological properties and contents of nutrients such as nitrogen, phosphorus and potassium of the needles. The results indicated that the number of chlorotic individuals increased with air pollution. The weight of needles and the number of corns per tree in the polluted site respectively, the contents of chlorophyll and nutritive elements of the needles in the polluted sites were lower than in the non-polluted site. In addition, the growth values of the height, diameter and volume of the pine in the polluted sites were lower than those of pine in the non-polluted site.

Based on the data collected from a small mixed forest watershed of Pinus densifora sieb. et Zucc,Pinus thunbergii Path and Chamaecypari sobtusa sieb. et Zucc. ex Endl. at Kiryu nature reserve and a small barren watershed at Jakujo nature reserve, Ootsu,Shiga,Japan,the pH values,electrical conductivities and concentrations of metal and nonmetal elements in rainfall ,throughfall ,stemflow and drainage have been studied. The results show that both the mixed forest ecosystem of pine and cypress and the soil draw from granite greatly (barren) affected the pH values and metal elements of rainfall while the effect of the mixed forest was greater than that of the barren. Moreover, the amount of input of most elements was larger than that of output in the ecosystems ,having a tendency of accumulation.

The photosynthesis, dark respiration and soil respiration of plant community in Kobresia humilis meadow were studied from 1990 to 1992 at the Haibei Research Station of Alpine Meadow Ecosystem, Menyuan County, Qinghai province. The characteristics of photosynthesis were measured using Infrared Gasanalyzer (IRGA). The results show that the diurnal variation of net photosynthesis was not obvious in June, but the midday depression appeared in July and August. the photosynthesis of plant community in K. humilis meadow was affected by rather low photosynthetic area index and by the light received by canopy leaves. It had obvious light saturation. The light compensation point and the light saturation point were lower, relative to the photosynthetic activity radiation (PAR) of full sun, which assembles the light response of the single leaves. The soil respiration of uncovered ground and the dark respiration of plant-soil system were not only influenced by temperature, but also related to soil water content and precipitation. The main factors of influencing the photosynthesis character of meadow community were. the strong radiation in plateau region, the lower photosynthetic area index and the turf structure due to the tight combination between plant roots and soil of K. humilis meadow.

The study deals with distribution, seasonal dynamics and cycling of nutrients in a Dicranopteris dichotoma community of Hong Kong.The results show that: 1) concentrations of N,P and K in live materials were greater that in dead materials, but greater in aboveground plant parts than in belowground plant parts. 2) Nutrient contents were greater in live materials than in dead materials, but greater in belowground plant parts than in above plant parts. 3) Above ground nutrient contents of current plants increased with increment of phytomass. However ,the production rate of dry matter exceeded uptake rate of nutrients so that the relative concentrations of N,P and K were reduced due to phytomass increase. 4)Although net primary production in the fernland was greater than those in the grassland and scrubland which are near the fernland, the N and P mass in net primary production of the fernland was less than that in the scrubland. 5) Most of N and P in the ecosystem were stored in the soil, in terms of their proportion to their total values. However, the vegetation contributed to about 36%～50% of K in the ecosystem, in terms of available K in the soil. 6) The contents of N,P and K in standing dead matter and litter increased gradually during the study period. This means that there was an accumulative process in the nutrient pool consisting of standing dead matter and litter of the ecosystem after fire. 7) The return of N, P and K by litterfall explained their 49. 1%,38.0% and 13.1%, respectively, in net aboveground primary production (NAPP). 1.2% and 46.6% of N and P in NAPP came from the internal cycling.

Based on the field experiment and the investigation on Mt. Jinyun, Sichuan, China, morphological responses and energy investment strategy of Pleioblastus maculata clone under the conditions of different water resource supply in microhabitat were analyzed. The results show as follows:1. Clonal P. maculata accumulated more biomass and produced less but larger ramets under higher levels of water resource supply. At different moisture conditions, spacer length and ramets size were variable, but internode length of rhizome was not significantly different at P= 0.05.2. The clonal growth of P. maculata seems to allow a foraging strategy that the clone produce longer rhizome with higher energy investment under lower levels of water resource supply in order to capture the resource and escape from a poor microhabitat. On the contrary, under higher levels of water resource supply, energy was mainly invested in growth of ramets.

In the range of soil relative water contents (SRWC) of 40%～70%, we observed that root growth of wheat got limited, root rate area (RA), root water potential (RΨw), root length (RL) and root dry weight (RDW) reduced obviously, root respiration intensity (Rp) increased, as soil water stress got serious. As SRWC increased RΨw increased obviously, Rp reduced, but RL, RDW and RA showed bellshaped response patterns. The maximum value reached for RDW when SRWC was 55%～62%, for RA when SRWC was 54%～57%, and for RL when SRWC was 55%. It is benefit for root deep growth and RA increase when soil moisture tended to be good. Nitrogen and phosphorus had very striking adjustment action on root physiological characters of wheat. Phosphorus nutrition was able to obviously increase RA, RΨw, RL, RDW, but decreased Rp. Especially, under conditions of serious water stress, the adjustment action was even better for RA, RΨw, Rp and RL. There was an obvious difference between nitrogen and phosphorus in adjustment action on root physiological characters of wheat. Under serious water stress, nitrogen was able to lead to decreasing RΨw, and show negative action. Nitrogen had no obvious action on RΨw under a slight drought: it had remarkable positive adjustment action on RΨw when soil water was enough. Nitrogen nutrition was able to raise Rp remarkably. It is of benefit to RDW to enhance application of nitrogen to soil as SRWC increased. The response of RL to nitrogen was not sensitive. Phosphorus could change water relationship in plant body and raise droughtresistance of wheat under water stress besides it acted as a kind of nutrition to promote root growth and development.

The relationships among the populations were investigated through calculating association coefficients as well as comparing RA, RD, RF and IV of main tree populations in three types of the natural secondary forest communities. Such interconnections were described using the diagrams of constellations. The results show that most pairs of the tree populations in the three types of the communities were either positively or negatively associated significantly. The associations were subjected to further theoretical analysis in the present paper. The results are significant for analyzing the inner mechanism whereby the communities are structured.

Using black shading net, we set up four light conditions (e. g. 100%, 24.5%, 7.5% and 2.5% of full light) under which the cuttings of poplar grown. The effects of light intensity on leaf growth, leaf anatomic structure, chlorophyll content, light-photosynthesis curve, growth of newly produced sprouts and biomass were investigated. The results show that 741 poplar is a light tree species. Biomass and other parameters were all higher under 100% light than the other light conditions. The plants had a strong compensation at the level of 24.5% of full light. The single leaf area, growth rate of newly produced sprouts, chlorophyll content and petiole length were larger, but total biomass was smaller, under full light than 34.4% of full light conditions. Under 7.5% of full light, the plants reached their limitation of shade tolerance. The plants were not able to survive for long term under 2.5% of full light conditions.

The effects of rainfall on the nutrient leaching and the seasonal variations of nutrients in rainfall, throughfall and stemflow in the moist evergreen broadleaved forest at the Ailao Mountain in Yunnan Province were analyzed and discussed based on the data collected during 1990～1992. The results show that the concentrations of N, P, K,Ca and Mg were different among rainfall ,throughfall and stemflow. The concentration and input of nutrients were higher in the rainy than in the dry season. The concentration of nutrients in stemflow was higher than that in throughfall which in turn was higher that in rainfall. The contributions to the nutrient input of the stands of the rainfall and the leaching from the trees were also discussed.

In this paper, the biologically absorbing coefficients and the contents in plants of trace elements were investigated for 12 medicinal plant species in Hainan Province. The results show that the coefficient differed among families, among, genus and among species. The difference decreased in the sequence of the elements :Mg>Al>Fe>Mn>Zn>Cu. The coefficient differed between species of the same genus, and between species of different habitats. The coefficient of Areca catechu in Hainan, for example, was greater than that in A. catechu in Thailand which in turn was greater than that in A. Catechu. The ratio of absorbed volume between elements decreased in the sequence of the elements: Mo>Zn>Cu > Mn > Ni. Fe> Mn >. The different plant parts differed in absorbed volume of the elements. There was a correlation of the element contents between the plants and the soil. In the plants, the contents of Fe, Mn and Zn were larger than those of Cu, Pb and Ni. For each of the elements, the content was greater in Gynostemma pentaphyllum than in A. Catechu.