Psammochloa villosa at Ordos Sandland Ecological Station (OSES) was investigated. P. villosa plants had a regular clonal growth, a clonal architecture of "guerilla" and a quite fast clonal expansion. The rhizomes connecting the ramets were able to maintain for at least 2 years. The results suggest that there is patential of a strong clonal integration in the species. The ramet populations of the species at OSES and Inner Mongolia Grassland Ecosystem Research Station (IMGERS) and those under conditions of monoculture and mixed with different species were compared. There were considerable variations in some important traits such as rhizome internode length,shoot height,ramet density and biomass between the monospecific populations at OSES versus IMGLES. At each of the two sites, differences in the same traits between monospecific population and population mixed with defferent species were also observed. The results imply that clonal plasticity may have a contribution to ecological adaptation in the species.

This paper deals with the water regimes of Sabina vulgaris community in China’s Maowusu Sandland. In the typical sites of Sabina vulgaris community, two sample plots were selected at the top dune and the depression, standing for the poor and good water condition, respectively. The effects of water deficit on the water regimes of the plant are discussed with the aid of field collected data of transpiration rate, stomatal resistance, water potential, community characteristics and soil water conditions, etc. The main results are: 1) Although transpiration rate of Sabina vulgaris was relatively low, water consumption of the community might be so remarkable that the individual plant might easily be confronted with conditions of water deficit, and 2) as a result , the degradation of Sabina vulgaris community was due partly to the shortage of water. 3) The lowland covered with sand, where water conditions is good, was more appropriate for planting Sabina vulgaris. However, in planting this shrub in the soft and hard ridges, or high moving dunes where ground water is unavailable, attentions should be paid to both the extent and density of this plant.

After 3-year studies of population and physiological ecology in the field, the physioecological characters of transpiration of endangered plant Mosla Hangchowensis under controlled condition were studied. Results show that: 1 ) The peak height of the diurnal curves of the transpiration (Tr) decreased with the decrease of soil water content. 2) There was a negative regression between Tr and the air relative humidity in the soil of saturation and medium water content, and a positive regression in the dry soil. This indicates that M. hangchowensis bad the self-protection mechanism in the dry soil. 3) On fine clays with thin cloud and humid air or cloudy in midday, the daily Tr was lower (2.6 and 2.8 mol·g-1·d-1) than that on typical fine day(3.4mol·g-1·-1). 4) In shade(40% full sunlight) ,the mean Tr dropped by 76%, and the responds of Tr to temperature and relative humidity were little, but to FPD was bigger than that to full sunlight. 5) Under the condition of 15～18℃ ,the Tr was only correlated with soil water content among the ecological factors. M. hangchowensis has some physio-ecological characters which are usually found for mesic to xeric species. The physio-ecological mechanism by which M. hangchowensis could only occupy the existing ecological niche—thin soil on open sunny rocks and the reasons for the impossibility for the species to expand to thick soil habitat were put forwards.

In China pine forest are mainly distributed in the subtropical zone and the temperate zone. In the eastern part of the subtropical and temperate zone,there are Pinus massoniana forest, P. armandii forest P. tabulaeformis forest, P. koraiensis forest,and P. sylvestris var. mongolica forest. Because of differences in species,origination and age of pine stands, their biomass is about 65～200 t·hm-2 and decreases with increasing of latitude. The contents of main nutrient elements in needles of pine tree are as follows: [N]>[K]≥[Ca]> [Mg]≥[P]. At the same time, the contents of the nutrient elements differed among the species. Interspecific difference in nitrogen content of the needles was as follows : Pinus armandii > P. massoniana > P. tabulaeformis > P. koraiensis>P, sylvestris var. mongolica. Phosphorus and potassium contents were higher in needles of P. tabulaeformis and P. koraiensi. Calcium content fluctuation was big and dependent on rock from which the soil developed. The nitrogen accumulation, among the five elements (N, P, K, Ca,and Mg),was about 25 %～40% of all in pine stands. Habitat, species and plant age affected the rate of nutrient element cycling. In general, the cycling rate of the nutrient elements of the pine stands in the subtropical zone was higher than that of the pine stands in the temperate zone.

Fine roots were sampled in a monsoon evergreen broad-leaved forest(MEBF),and a nearby mixed coniferous (Pinus massoniana ) and broad-leaved forest (MCBF), located in Dinghushan Biosphere Reserve. The standing pools of live and dead fine roots in the 0～40cm soil depth were sampled seasonally for one year, annual dry mass loss of the decomposing fine roots was measured and mortality and production were calculated. The comparison of soil coring and in growth method for estimating the fine-root production in the surface soil (0～20cm) was also made. The mean standing pools of roots ≤2mm and 2～5mm in the 0～40cm soil were 6.59 (29.9%) and 4.81(22.9%) t·hm-2 for the MEBF, while 5.35(34.4%) and 4.24(24.0%) t· hm-2 for the MCBF with the portion of dead roots given in parentheses. The standing pool did not fluctuate dramatically with various sampling occasions. In the MEBF, annual mass loss, mortality, net production for fine roots were 0.90,1.59,2.65t·hm-2·a-1 (≤2mm),and 0.41,0.63 and 1.25t·hm-2·a-1 (2～5mm),respectively. While the corresponding values in the MCBF were 0.80,1.41,2.42 t·hm-2·a-1 (≤2mm) ,and 0.37,0.62,1.21t·hm-2·a-1 (2～5mm) ,respectively. The annual turnover rates were 0.57(≤2mm) and 0.34 times·a-1(2～5mm) for the MEBF, and 0.69(≤2mm) and 0.38 times·a-1(2～5mm) for the MCBF, respectively.

Studies on the pollen dissemination of Castanea mollisima in the air at the Caiyuan area, Qianan county indicated that blooming date of the plant differed among years, and the pollen concentration varied sharply with it. Pollen concentration in the air was deeply influenced by the air temperature during the blooming and also by the precipitation to the end of peak florescence, but it is little influenced by the sunshine. The correlation coefficient between the yield and the pollen concentration of C. mollissima during the peak florescence was 0.998～0.999. The predicting error of model based on two-year data was 5.7 % in maximum, 1.13% in minimum and less than 4% on average. The yield was predicted two months earlier than the harvest time. Estimating yield of C. mollissima or crops based on pollen concentration is a good predicting method with high precision and little cost, and much ahead in time.

An inhibitory effect of Acorus tatarinowii on algae growth was found. In addition to the competitions of light and mineral nutrients between Acorus tatrinowii and algae ,the mechanism of this inhibitory effect was mainly due to an excretion of some organic substances from the root system and rhizome of Acorus tatarinowii which may injure and abate algal cells(allelopathic effect). When algal cells were treated with cultured water of Acorus tatarinowii, chlorophylla was destroyed, the photosynthetic rate of algae markedly declined and the ability of cells to reduce TTC decreased. Under fluorescence microscope, it was seen that algal cells turned from bright red to bluish green.