A Study On Melica Przewalskyi Population Spatial Pattern And Response To Soil Moisture In Degraded Alpine Grassland

Under the influence of the global change plant distribution patterns showeddiversification trend, the Invasive species have stronger reproduction, adaptability formedsingle advantage population, arid and semi-arid region, single advantage populationcommunity became one of the main forms of vegetation degradation, the single advantagepopulation patch likely can change soil moisture distribution pattern in small scale, thusoptimize distribution area diffusion mechanism of plant population response onenvironmental. Hence, research the relationship between single advantage population patternand soil moisture play important roles in uncovering plant plasticity mechanism for soilmoisture change, deeply understanding the synergic relationship between plant andenvironment. In Qilian Mountains northern slope cold mountain region, the specialgeographical environment and climate conditions, add the climate change, over-grazinginterference, Melica przewalskyi rely itself biologische merkmale, plasticity and Adaptabilityfor environment, formed mass unequal area, growprolifically single advantage populationpatch，research of Melica przewalskyisingle advantage population contribute to cognition theInteraction between vegetation and environment in arid and semi-arid areas. For thatreason, the text combine Point pattern analysis and community dynamics research Melicaprzewalskyi population distribution patterns, soil moisture, population biologische Merkmalein Qilian Mountains northern slope.（1）In Melica przewalskyi type deteriorated grassland, patch in formation, diffusion andstable stage population height, density, coverage by the center to the edge of decreasegradually, recession stage to edge by center increased gradually, patchs formation early,biodiversity is higher, with community succession development Melica przewalskyibiodiversity gradually reduced, then rose, biomass magnify then decreased.（2）Vegetation on soil moisture change characteristics of flexibility and counterproductive.patchs by center to the edge of soil moisture increased gradually, patchs areas of soilmoisture in greater than patchs outside, patchs internal soil moisture and vegetation majorbiological characteristics by negative correlation between transition to positive correlation.Melica przewalskyii has obvious plasticity, through the long-term adaptation in aridenvironment, the water demand of individual plant less than primary zonal vegetation,changed the fine-scale soil moisture distribution structure, through the population with soil moisture interactions, formed flourish single dominant population patches.（3）Melica przewalskyi from companion species-dominant species-Single advantagespecies, space pattern translated from aggregated distribution to random distribution,competition relationship translate from interspecies to intraspecific, Stipa Krylovii fromdominant species-companion species, space pattern translated from random distributiontoaggregated distribution. Melica przewalskyi formed pattern control relation to StipaKrylovii in much scale，but Stipa Krylovii have not pattern control relation to Melicaprzewalskyi.（4）Melica przewalskyi population spatial pattern transitted from clumped to randomdistribution at four stages, soil moisture tended to increase from center to edge of patch;Melica przewalskyi patch diffused to the high soil moisture with concentric circles wayduring the formation stage, diffused stage and stable stage, and the radius of patch expandfrom0.5m to1.5m, the population height, density and coverage were decreased from centerto edge of patch; And then the center of patch appeared naked at recessionary stage, theheight, density and coverage increased progressively from center to edge of patch inconcentric circles way. The spatial pattern and main biological characteristics showeddifferent correspondence relationship with soil moiture at different stages.