Based on variation of growth parameters and development parameters, foraging growth pattern and resource allocation of clonal Leymus chinensis population were studied. Relationships between the law of resource allocation and microhabitat quality of the population were analyzcd in terms of mathematic methods. Foraging behaviour of this population was also discussed. The results showed that foraging growth parttern of resource alloation could be described using allocaion function models in which ψ=0.5, μ=l.0,Tr=7, and Ts = 2.

The experiment was carried out with two grape varieties, ’Kyoho’ (Vitis vinifera × V. labrusca) and ’Early Agatc’ (V. vinifera), and with five different canopy structures through which a series of different canopy PAR interception and distribution types were established, in vineyards of Beijing area (North China) during 1988—1992. The results showed that there existed significant or very significant positive linear correlations between canopy PAR interception and net photosynthetic rate, between canopy PAR interception rate (PFRL) [and single leaf (PFRI)] and the percentages of total fruit dry weight in aerial biomass dry weight, between PFRL (and PFRI) and the contents of total berry sugar in fruit, and between PFRL (and PFRI) and the millesmal values of total anthocyanin production in the sink to total fruit dry weight. It suggested that varying canopy PAR interception and distribution through management of canopy structure of vineyards could regulate efficiently photosynthate “sink-source” relation of vines and metabolic direction in grape berry. The canopy having a high PAR interception and a good PAR distribution in the canopy could not only supply grapevine with a full photoassimilate “source” to satisfy the needs for grape yield and quality, but also permit a higher partitioning coefficient of photoassimilate to fruits by regulating the “sink” relations between organs, and be favourable for the biochemical comosition of berry quality in metablism of fruit.

The processes of forest succession could be expressed by the dynamic characteristics of dominant populations in forest. The dynamic characteristics of two heliophyte species, Castanopsis chinensis and Schima superba in forest succession in Dinghushan were studied. The main results were as follows: 1. The niche breadths of the 2 species increased after their intruding in the needle-leaved forest, and reached the maximum when they became the dominant populations in evergreen broad-leaved forest, and then reduced gradually, but did not disappear at the climax stage. 2. In the process of the succession, changes in distribution patterns of the two populations were from clustering to random. 3. During the succession, the association and niche overlap of these two populations with Pinus massoniana population decreased, while with some mesophyte populations increased at first and reached at the highest in the evergreen broad-leaved forest stage, then reduced at the late stage. The results suggested that the features of the two populations were that of pioneer species; and the cycle and regeneration of mature community could cause the uneven and inlaying in community structure which is the reason for existence of these heliophyte population at the late stage of succession.

Evapotranspiration from the 3 plant community-types was measured by the method of soil column at Inner Mongolia Grassland Ecosystem Research Station of the Chinese Academy of Sciences. The 3 community-types were typical steppe communities on the zonal habitat dominated by Leymus chinensis or Stipa grandis, the Artemisia intramongolica community on the sand lands, and the Agrostis alba meadow community on the river floodland. The results were as follows: 1. The transpiration from the meadow community was the highest (9.2 mm · d-1), being the 2--3 times of the other two communities; while the evaporation from the meadow was the lowest evaporation (0.4mm·d-1),being only 1/4 of that from sandylands or 1/8 of that from steppe. 2 A compartive measurement of the evapotraspiration from the two typical steppe communities dominated by L. chinensis and S. grandis showed that the evapotranspiration from L. chinensis community(4.4—5.0mm· d-1) was higher than that from S. grandis community (3.5—3.8mm· d-1).Ratio of transpiration to evaporation (T/E)was also much higher in L. chinensis community (=2) than in S. grandis community (= 1 ). 3. The seasonal chenge of evapotranspiration from L. chinensis community was in accordance with the change of air temperature; but showed a big flactuation due to change of rainfalls. The water budget of the community was aproximately balance.

The chemical characteristics of phosphorus contents of 15 species in the Shandian River Basin, Heibei Province were measured, and the seasonal changes of phosphorus contents of six crops were studied. The results were as follows: The average phosphorus contents of the 15 species was 1.38±0.62mg · g-1 with the highest, 2.25mg·g-1, and the lowest, 0.88mg· g-1. Such a result was resemble to that investigated in Haihe River Basin and Xilinhe River Basin near the same region (North China). The types of seasonal changes of phosphorus contents of the 6 crops varied with the different kinds of crops. For the Gramineae crops sush as Triticum aestivum and Avena nuda and the oil-bearing crops Linum usitatissimum,the phosphorus contents changed as a series of, mature period growth > seedling period > the vigorous period (P<0.05); For the bean crops like Pisum sativum and Vicia faba, the seedling period > vigorous period > mature period (P<0.001); while for the stem-tuber crops, Solanum tuberosum, the seasonal changes of phosphorus content was the vigorous > seedling period > mature period (P<0.001). The different organic parts showed the different patterns of seasonal phosphorus changes, for roots, stems and leaves of the crops (except for Solanum tuberosum), seedling period > the vigorous period > mature period, while for the fruits, the end of mature period > the fruit-forming period. The ratios of phorphorus content between root and stem, stern and leaf, as well as stem and fruit could indicate the movements of phosphorus in the plants. The results showed that phosphorus moved along the way of root→ stem →leaf during seedling period or the vigorous period, and root →stem →fruit during the fruit mature period.

A new dynamic vegetation index (VI)-yield model, that is, the leaf area duration (LAD)-yield model was structured for estimating winter wheat yield according to the measured reflection spectral data on the wheat field, and the relationship between wheat yield and LAI. The model had the information on the photosynthetic area and time during the later period of wheat growth, i. e., the period from the heading stage to the end of filling stage. The accuracy of the estimated wheat yield arrived up to 98% .In addition, the winter wheat yield was also estimated by a VI-yield model in a given wheat growing stage, and the VI in several main wheat growing stages were used for this purpose. The results suggested that the best season for estimating wheat yield using the VI-yield model was in the middle of wheat filling stage for the case study in Yucheng, Shandong province. The accuracy of the estimation could arrive at 96%.

The autumnal changes in contents of carbohydrate, soluble protein and the enzyme activities of catalase (CAT) and superoxide dismutase (SOD) in the root of Clinelymus nutans (griseb) Nevski were studied in the cold mountain areas, The results showed that both the contents of carbohydrate and soluble protein and the enzyme activity of the CAT and SOD increased with the temperature decrease in Autumn and early Winter; and these four attributes were higher in the forage root collected in the burned grassland than that in the non-burned grassland. Since the high contents of carbohydrate and protein in the forage root at the end of Autumn could provide energy for forage to resistant cold in Winter and provide nutrients for forage ger mination in the following year, the forage in the burned grassland grew better than that in the non-burned grassland. The high enzyme activity of the CAT and SOD in the Autumn was also related to a high resistance to low temperature.

Field experiments were conducted in 1992 and 1993 in Beijing and Tangshan regions, two representatives of the Haung-Huai-Hai region, to study the functional relationships between the relative weedy or weedfree days of naturally infecting weeds and the relative yield of summer maize. Models for calculating the eco-economic threshold period for controlling the weeds in maize feild were established. The results showed that the eco-economic threshold period for controlling the naturally infecting weeds in summer maize feild ranged from 11.2% to 50.9% of the total growth days of maize after crop emergence in this region. This is the critical period to remove all of the weed damage and to maximally utilize the role of the weed flora in reducing the loss of water, nutrients and soil during the growth season of maize in this region.

The tree relative growth equations were established on the basis of measurement values of 30 sample trees using harvest method, which were used to estimate the forest community biomass. The result showed that the above-ground biomass of the typical community dominated by Platycarya longipes and Cyclobalanopsis glauca in Maolan Karst forest was 168.02t/hm2. It is ranked within the forest ecosystems of low biomass. The biomass variances of 3 different forest types distributed on mountain ridge, mountain slope and mountain valley in Maolan Karst region were investigated. The biomass components were analyzed according to life form, storey and species within tree stratum. The productive structures of some tree species as well as their reasons were also discussed.

The distribution laws of soil microorganism in the soil of L. chinensis grasslands were investigated in Northeastern China Plain, and the effects of soil features on them were analyzed. The results showed that the amount and the net biomass of microorganism was the biggest in the soils under L. chinensis community and weed community, the smallest in the soil covered by the Puccinejjia tenuifora community, and moderate in the soil of Cleistogenes squarrosa community. Among the measured 11 soil factors, the interactions between pairs of soil total N-total P, active organic matter-total P, pH- total P, pH-total K, total K-total P, active organic matter-total N, active organic matter-total K, organic matter-total N were distinct, with the correlation coefficients of 2.90--5.94. The direct effects of total P,N, K, pH and active organic matter on the microbial biomass were significant, with the path coefficient of 2.02--6.15.

The early restoration of vegetation and soil on the felling-fields of Fagus engeriana forest at Tai-Yang-Ping in Shengnongjia mountain areas were investigated. The species diversity, ecological dominance, life-forms and optimal habitat, as well as community similarities were comparatively analyzed. The results suggested that the vegetation and soil in all kinds of felling-field of different age and different habitat were restoring rapidly and stably, but there existed a spatial and temporal heterogeneity in species composition, vegetation structure and soil nutrients during the restoration.

The hilly area in the central part of the Sichuan province is one of the most important region for construction of the protective forest systems in the upper and middle reaches of the Yangtze River. The vegetation dynamics of a young Alnus cremastogyne and Cupressus funebris woodland with sown herbage on the bare hills in the region was investigated. The results showed that the coverage and biomass of the understorey herbage communities increased simultaneously with the growth of the young trees. The restoration of the vegetation in the hilly area could be accelerated by planting trees together with sowing herbage.