Pollen Dispersion, Pollen Viability and Pistil Receptivity in Leymus chinensis

Modeling SOC and NPP responses of meadow steppe to different grazing intensities in Northeast China

Precipitation is considered to be the primary resource limiting terrestrial biological activity in water-limited regions. Its overriding effect on the production of grassland is complex. In this paper, field data of 48 sites (including temperate meadow steppe,temperate steppe, temperate desert steppe and alpine meadow) were gathered from 31 published papers and monographs to analyze the relationship between above-ground net primary productivity (ANPP) and precipitation by the method of regression analysis. The results indicated that there was a great difference between spatial pattern and temporal pattern by which precipitation influenced grassland ANPP. Mean annual precipitation (MAP) was the main factor determining spatial distribution of grassland ANPP (r~2 = 0.61,P ＜ 0.01); while temporally, no significant relationship was found between the variance of AN PP and inter-annual precipitation for the four types of grassland. However, after dividing annual precipitation into monthly value and taking time lag effect into account, the study found significant relationships between ANPP and precipitation. For the temperate meadow steppe, the key variable determining inter-annual change of ANPP was last August-May precipitation (r~2= 0.47, P = 0.01); for the temperate steppe, the key variable was July precipitation (r~2 = 0.36, P = 0.02); for the temperate desert steppe, the key variable was April-June precipitation (r~2 = 0.51, P ＜0.01); for the alpine meadow, the key variable was last September-May precipitation (r~2 = 0.29, P ＜ 0.05). In comparison with analogous research, the study demonstrated that the key factor determining inter-annual changes of grassland ANPP was the cumulative precipitation in certain periods of that year or the previous year.

Spatial and temporal relationships between precipitation and ANPP of four types of grasslands in northern China.

Demography of reproductive and biomass allocation of grassland and dune Leymus chinensis on the Songnen Plain, north-eastern China

Response of phytoliths in Phragmites australis to environmental factors in northeast China

According to the yield of Aneurole pidium chinense (Trin.) Keng community and climatic variations from 1978 to 1990, the relationship between the yield and climatic factors was probed by correlation analysis. The results showed that the correlation degrees of sigma7--8 months^ precipitation, sigma6--8 months^ precipitation/sigma6--8 months^ temperature and sigma4--7 months^ sunshine in relation to the yield were 0.47, 0.41 and 0.35 respectively and the correlation was in the order of 0.47>0.41>0.35. Water was the main limiting factor affecting the community yield. The effect of interation of water and heat factors on the yield was also extremely remakable. The yield of A.chinense community was simulated by using multiple regression equations and periodic variance analysis. reaching a simulated rate over 90%.

Guo Ji-xun

Papers

Effect of Climatic Factors on the Yield of Aneurolepidium chinense (Trin.) Keng Community

Contrast Study About Litter Dynamics of Main Communities in Aneurolepidium chinense Grassland Region in Northeast of China