Annual Dynamic Characters Of Community Structure And Functional Traits At Patch Scale In A Desert Steppe

Steppe,a most widely distributed types of vegetation in the world,provides abundant net primary production substance for human beings.Meanwhile,it also has functions of water source conservation,modification,wind prevention and sand fixation,soil and water conservation,and biodiversity maintenance.Steppe fragmentation characterized by patchy community distribution is a common form of degraded steppe in arid areas.Based on the properties of surface soil,three common patches were selected to continuously monitor the month variation of growing season and estimate the trait parameters of vegetation communities at patch scale in desert steppe combined with UAV hyperspectral imaging technology,we examined the changes of community structure and vegetation traits at patch scale.The main conclusions are as follows:(1)Species richness of three patches was low.There was no significant change in the plant species composition of patch A and patch B.There were fewer new plant species in the growing season,and the species richness of the community was higher.The species composition of patch C was larger than that of patch A and patch B,and the main dominant species in the patches maintained a high dominant position throughout the growing season.The species diversity community complexity,and individual distribution of species between patch A and patch B were basically the same.The community diversity index of patch C was lower than that of patch A and patch B.In comparison,S.breviflora is the dominant species,and the community with leguminous plants as the main associated species have higher biodiversity and maintain a more complicated community structure.(2)According to analysis on the dynamic variation of ecological niches,community diversity in patch C was low,and the interaction relationship between species pairs was weak.However,the species diversity?niche of the main species and interaction between species pairs in patch A and patch B was high.The complexity of community organization within the patches and the intensity of interaction between species were one of the important prerequisites for maintaining community stability and pattern.On the seasonal scale,the plants in the patche mainly adapt to the environmental variation in different growth stages by adjusting the niche width,therefore,they maintain a high adaptability to the environment.(3)Among different patch communities,dominant species had different abilities and methods to utilize resources.Patch A and patch B were mainly composed of S.breviflora,and the community structure was relatively stable.Meanwhile,the utilization efficiency and light-capturing ability of species for habitat resources was strong.Contrarily,the dominant species of patch C had different resource utilization abilities in periods on growing season.(4)The NDVI changed greatly under different patches during the growing season,and the degree of NDVI changed within the patches was different,too.Different patches were most restricted by N/P during the growing season,and the effects of SLA and WBI on biomass and the intensity of the interaction changed with the seasons.The biomass composition of different patch types is greatly affected by the uniformity and the degree of individual distribution during the vigorous growth period as well as the complexity of the community in the early and late stages of the growing season.