Effects Of Nutrient And Salt-alkali On The Interspecific Relationship Between Leymus Chinensis And Stipa Baicalensis

Interspecific relationship is the base of constructing biocommunity, so the study of interspecific relationship is the interface between population ecology and community ecology. Leymus chinensis and Stipa baicalensis are both constructive species of meadow steppe of northeastern China. After S. baicalensis steppe assarted, L. chinensis community appeared during the succession. It is important to study the interspecific relationship between L. chinensis and S. baicalensis. The changes of the interspecific relationship under different nutrient, water, and salt-alkali levels were analyzed. The study aims to reveal the effects of different environmental factors on the interspecific relationship and the life strategy of the two species against adversity and search for the most important factor of effecting the interspecific relationship, then try to predict the change of community composition under the specific environment and understand the community structure and succession, thus, to provide rationale for restoration, re-establish and management of grassland.We investigated the importance of nutrients, soil moisture, salt-alkali, and interspecific competition levels on the height, biomass, and the biomass allocation patterns of the two species. A factorial experiment was conducted with high-low nutrient levels, high-low soil moisture levels, and high-low salt-alkali levels. Under the experimental conditions, the soil moisture did not create a treatment and the soil moisture treatment was dropped from the total analyses. The results showed that:There were effects of nutrient and salt-alkali on the interspecific relationship between L. chinensis and S. baicalensis. The biomass of the two species grown in mixture was lower than in monoculture at low nutrient and salt-alkali levels, so it showed competition. But they avoided competition when at high nutrient and low salt-alkali levels because of their different demand of resources. It could be relationship of competition between the two species, because they had the same demand of restrictive environmental resources at high salt-alkali.The results of this experiment suggest that L. chinensis and S. baicalensis both increased number of tiller to expand the range of obtaining resources to look for new habitat against the lack of environmental resources. The results also suggest that L. chinensis is an inherently better competitor than S. baicalensis.