Study On Spatial Distribution Pattern And Spatial Association Of Stipa Krylovii Population In Alpine Degraded Grassland

Spatial pattern is comprehensive results that are interrelated and interact between Itsbiological characteristics and environmental factors, which is an important means to studythe population features, intra-specific and inter-specific relationship. The spatialdistribution pattern and spatial correlation of plant population are the presentation of theform on ecological relations, which can reflect the space distribution, the condition ofusing resources and the role of population in the community, and reveal the complexrelation of interdependency and mutual control as well. The spatial pattern of dominantpopulation is a major feature of community structure, which both the reasonable reflect ofthe population and communities, is also the mark of dynamic and stability of thepopulation and communities. Under the over-grazing and global climate change influence,natural pasture seriously degenerate, the dominant population has replaced, it changed thebalance of payments of matter and energy and the distribution pattern of resources, whichwill have an effect on the competitive power of species and result in forming differentspatial pattern. Therefore, studying the spatial pattern of dominant population undoubtedlyhas important meaning to reveal the degeneration mechanism of grassland ecosystems andformulate restorative measures. For that reason, we study the spatial pattern and spatialassociation of Stipa krylovii population in alpine degraded grassland using the communitysurvey method and point pattern analysis method in order that reveal the scaletransformation features of the spatial distribution pattern and spatial association in theview of patch feature and size structure of population, and understand the updatemechanism of plant population for grazing interference.Draws following conclusion through the research paper:(1) Along with the natural pasture degeneration process extension, the S. kryloviipopulation showed that: First, the size structure of S. krylovii population changed fromstable structure to instability structure. The small bunch of0.1-1.0cm in heavydegradation was greater than no degradation. At the same time, the proportion of bigbunch was significantly higher than others in no degradation. Second, the density andpopulation territory area of S. krylovii population in heavy degradation was significantlylower than no degradation, but its total area of hole in heavy degradation was greater thanno degradation, and territory density increased firstly and then reduced. Third, Along withthe aboveground biomass and plant height of the sexual plants developed, the aboveground biomass and plant height of the vegetative plants showed the oppositechange tendency.(2) Patch is the basic ecology unit of S. krylovii population which can reveal thestatus and role of plant community. Patch broken is the crucial factor in the process of S.krylovii population colonizing and recession. The basic model of S. krylovii populationpatch broken: first, the individual of S. krylovii death in the center of population patch, andgradually to the surrounding divergence, which leading to original patch divided intomultiple smaller diameter patch and further differentiation. Finally, S. krylovii declined inalpine degraded grassland along with population patch broken and mattic epipedondisappeared.(3) Along with the natural pasture degeneration process extension, the aggregated isthe important pattern type of S. krylovii sexual plants, and the aggregated scale increasedwith the aboveground biomass and plant height of the sexual plants developed. Meanwhile,the aggregation and regular are the important pattern types between the S. kryloviivegetative plants, and the aggregated scale decreased with the aboveground biomass andplant height of the sexual plants reduced, as well as the regular scale increased. Thereduplication of aggregated between sexual plants and vegetative plants developed alongwith the natural pasture degeneration process extension, as well as the scale increased.Therefore, the spatial association exist complex combination characteristics. Theconclusion showed that: under the influence of jamming activities, S. krylovii may take ther-strategy that can reduce asexual reproduction input and increase sexual reproductioninput, which can maximum occupancy community resources.(4) As the natural pasture degeneration process extension, the spatial distributionpattern of S. krylovii is transformed from aggregation pattern to random or regular, and thespatial association among different size classes is transformed from positive correlation tono significant or negative correlation. Spatial pattern among different size classes existeddifferent characteristics: the random and aggregation is the major pattern of plant size Aand plant size B, and it transformed from random to aggregation; we can found that onlyplant size C showed aggregation, under moderate degradation conditions. Spatialassociation among different size classes was changed on the different scale anddegradation gradient: the spatial association scale of size A and B increased, as well assize A and C; no significant correlation or negative correlation are the major typesbetween plant size B and C, and the scale of negative correlation increased. The changesof size structure of S. krylovii population, as well as the competition, which can effect the scale conversion of spatial pattern and the spatial association, it can reflect the updatemechanism of plant population for grazing interference.