C is found to be the most abundant element in the various plants of 31-aged Robinia pseudoacacia plantation, especially in the trunk of Robinia. The leaf of Robinia has high Contents of N and Ca. K in the above-ground part of Cleistogenes caespitosa is very plentiful. The leaf of Vitex negundo var. heterophylla has much Fe. The small roots of plants are rich in A1 and Na. The leaves of Zizyphus jujuba var.spinosa contain more Mg and Mn.The accumulation of chemical elements in various layers of the plantation decreases in the order of C>Ca>N>K>Mg>P>Fe>Al>Na> Mn>Cu>Zn.The accumulation of different elements in the shrub layer is higer than those in the tree layer except C and Ca. Comparing the amount of elements in litter with which in plantation, the ratio of Na is the highest one with the higher ratio of Ca, Mn, Fe, Zn. These elements will gradually return to the soil. The ratio of P is lower, less P from litter will return to soil. The sequence of Ca>N>Mg>Fe>K>P> Na, Mn>Al>Zn>Cu is shown in soil nutrient pool. The concentration ratio of K, Al, P between plant and soil is significant.The ratio of accumulations of K, P, Al in plantation to those in soil nutrient pool is also higher. The content of K, P, Al in the soil is relatively not abundant.

The ecological conversion and effect of urbanization on growth of plants based on the data from two function areas, the Cherry Gully Sight-seeing area and the area of the Capital Steel industry are studied in this paper. The results showed that there are great differences in air temperature, relative humidity. precipitation and the contents of pollutants in rain, dust and plants between the two function areas. The blomingand fruit-bearing period of most plants in industrial area are earlier but the leaf changing-color period is later than those in Sight-seeing area. Some plants couldn’t even blossom and bear fruit. Although some plants could blossom but the flowers were less in number and their fruits were smaller. The leaf surface area of nine broad leaf’ trees and shrubs and the yearly twig growth rate of four evergreen needle leaf trees growing in Sight Seeing area were 0.5—l times as big as those in industrial area.

In this paper, the vegetation on the lower mountains near West Lake in Hangzhou has been classified with Braun-Blanquet Method based on 132 plots. It can be divided into two Associations. (Association of Schima superba and Association of Pistacia chinensis) , seven Subassociations, and six Variants. 28 groups of diagnostic species are analysed. The characteristics of the syntaxa and their environmental conditions as well as the spatial continuity of the plant communities are well shown by the research.

The research indicated that the total aboveground biomass and the yield of various nutritive substances of the population of Astragalus adsurgens were featured in the single kurtosis during growing period. The fourth-order polynemial could be used to discribe and predict the yield in every period. The peak values for various organ biomass and the yield of nutritive substances were different The aboveground biomass reached the highest in early Sept. of florescence, of which the highest stem biomass occurred after florescence and the highest leaf biomass before it. The highest content of crude protein and crude fat appeared before the formation of highest biomass being 166g.m-2 and 29g·m-2 respectively. The peak for crude fiber and N-free extract appeared after biomass peak being591g.m-2 and 663g.m-2 respectively. The biomass formation of the herbage was a process in which soil moisture was of deficit gradually. There was obviously a negative correlation between the aboveground biomass and soil water storage in root zone (3m) during the period from turning green to peak biomass. The CGR was a single kurtosis, with its maximum occurred in early July (14.9g.m-2·day) . The NAR had a short increasing period but RGR continuously went down. The nutrition content and their accumulation rates were markedly different in various organs during growing period.

The study of the succession of plant communities in the abandoned arable lands in the area of subalpine meadows of Gannan prefecture, is made by inferring from comparing the representative sites of abandoned arable lands of different ages. The analysis of community composition in succession shows (1) Importance of the grasses and sedge plants in the’ early stages of succession they rapidly dropped from 71% to 6% in 12 years, and as a result of the aggregation and spreading of grasses and sedge, plants, they recovered gradually to 30–40% the importance of weeds enhances rapidly in the early stage of succession and reduces in the later ones of succession; but the importance of poisonous herbs remains steady, acounting for about 10% of the community. (2) The species richness, Simpson′s diversity and eveness of the community increase while its dominance decreases with the development of succession. (8) The dominance diversity curve of the initial community is roughly geometric; as species are added, the curve approaches to a lognormal distributions but in the final stage, the curve approaches a MacArthur brocken-stick distribution.

Weeds are an important component in the farm land where a complex ecological relationship exists among weeds. crops and the environment. The investigation of this relationship has a great significance both in weed control for crop production and in theoretical study of cultivated vegetation.By using cluster analysis, an obvious correlation between weed types and soil types (correspond to soil genera) is found in alluvial plain where no obvious climate difference occurs. In the classification of weed types on dry farm land, the diversity of ecological conditions is of greater significance than dominant crops. Since most of the weeds have widely ecological amplitudes, the cluster analysis method is more objective than using dominants alone in weed classification. This paper also points out the worst weed species With their distribution, seasonal harmfulness and the degree of harmfulness in different environmental conditions.

The canonical analysis can deal with two kinds of variables simultaneously and the interrelated coefficient results. Ten plant associations and their soil characteristics of Yellow River delta have been analysed by using this method. The canonical interrelated’ coefficients are 0.9 and 1. All the canonical variables have been calculated with the whole information of primary data retained. It is shown that there exists a close inter relation between the dynamic changes of vegetation and its soil characters. The dynamic change of soil water and salt is the restrictive factor of vegetation succession. The canonical variable ordination shows directly the succession relationship between plant associations. This method offers, a great help to the study of plant community distribution and vegetation succession.

By means of the quantitative and qualitative combining method, Liaoning province is divided into 7 first class vegetation areas, 15 middle-class vegetation areas and 25 lower-class ones on the Map of Liaoning Vegetation scaled 1:500,000. Each vegetation area divided has not only quantitative basis, but also conforms to the pattern of regional vegetation differentiation. A working procedure of the vegetation regionalization which is followed by this study has been given at the end of the paper.