The Study On Spatial Pattern Of Aboveground Biomass In Different Grassland Types

Spatial heterogeneity is an important property of ecosystems and is also considered as a ubiquitous feature of nature. Spatial heterogeneity of vegetation is the core content of landscape ecology, as well as one of the main driving factors of the biological process, which affects the biodiversity and productivity pattern of vegetation, and plays an important role in the ecosystem stability, material circulation, energy transformation of vegetation community and population structure. Although the spatial pattern of vegetation has been widely studied, there have been few studies on the method of spatial heterogeneity of grassland aboveground biomass. This study aims to explore the method in analyzing the spatial pattern of aboveground biomass of grassland vegetation community, and discuss the rule of aboveground biomass of grassland vegetation community and spatial heterogeneity, and their relationship between biomass and spatial heterogeneity.The extensive field survey was conducted at the natural grassland in Bin County and a weedy community in Yangling district of Shaanxi Province in 2014 and 2015, respectively. We placed 100 0.5 m × 0.5 m quadrats in each type of grassland using random-sampling method. The mowed plants in each quadrat were identified and classified as species, and the materials were dried and weighed. We recorded the aboveground biomass data of each species per quadrat. The method of data analysis uses the power-law model and the gamma distribution model. The main results are as follows:1. In the power-law model of aboveground biomass of different grassland communities types, the regression line has the high determination coefficient, all of them are more than 0.9, and its regression residual value ? is relatively smaller, which suggest that the spatial distribution of aboveground biomass of each species in grassland vegetation community is fit well to the power-law model;2. We use the gamma distribution and power-law model to analyze the spatial heterogeneity of grassland communities vegetation in different grassland types, the negative correlation between spatial heterogeneity index and grassland aboveground biomass was ascertained by using power-law model(P < 0.01), that is to say, with the increase of the spatial heterogeneity in the grassland community, the aboveground biomass of its species tended to be on a decline.3. The Dominant species that have larger biomass determines the whole degree of spatial heterogeneity in grassland community;4. The power-law model is more simple, convenient and intuitive than the gamma distribution model when analyze the spatial heterogeneity of aboveground biomass of grassland vegetation;5. The power-law model is an effective and simple analytical method for studying the spatial pattern of aboveground biomass of vegetation community at a small scale, which can be completely replaced by the gamma distribution model, which provides a new application to quantitatively study the spatial pattern of aboveground biomass in grassland communities.