Effects Of Plateau Zokor-Mound On Plant Community And Soil Nutrients In Alpine Meadow

The plateau zokor(Eospalax fontanierii)is a small underground rodent that is unique to the Qinghai-Tibet Plateau.The mounds created by plateau zokors are mosaic in the alpine meadow.The effects of plateau zokor-mound include the bare spot effect and the edge effect,thus affecting the alpine meadow comprehensively.Edge effect is a phenomenon of habitat disturbance that caused by plant community and individual adaptation on the edge of mound.The structure and function of plant community in the marginal area will change to a certain extent.At present,the researches on mound effects of plateau zokor mainly focus on the bare spot effect,and only a few studies focus on the edge effect around mounds.Whether the bare spot effect on mounds or the edge effect around mounds,most of the existing studies are confined to one site.The plateau zokor distributes in a large area,and there are great differences in the ecological environment between different habitats.However,whether the bare spot effect on zokor-mound or the edge effect around zokor-mound are similar in different sites still needs scientific researches to provide evidence.Therefore,it is necessary to simultaneously carry out the bare spot effect and edge effect of plateau zokor mounds at two or more locations in order to clarify the common characteristics of the effects of plateau zokor-mound.Therefore,this study took Luqu County and Xiahe County of Gansu Province as study sites,and studied the response of plant community characteristics and soil nutrients to the effects of plateau zokor-mound simultaneously.The main results are as follows: 1.The bare spot effect of zokor-mound was mainly caused by 1-2 years old forbs in the bare area of mound,and the edge effect of zokor-mound was mainly caused by perennial Gramineae and perennial forbs in the marginal area.The response of the bare spot effect and edge effect of new-born zokor-mound in Luqu Country and Xiahe County were similar.The bare spot area was dominated by 1-2 years old forbs,and no Leguminosae and Cyperaceae were found.The edge area was dominated by competitive and tolerant perennial Gramineae and perennial forbs,such as Elymus nutans,Potentilla fragarioides,Poa poophagorum,Artemisia frigida.2.The bare spot effect of zokor-mound produced lower plant height,coverage,biomass and richness,while the edge effect of zokor-mound produced greater community height,aboveground biomass and species richness.The response of the number and apparent characteristics of the plant communities to the effects of new-born mounds created by plateau zokor in Luqu County and Xiahe County were similar.Compared with the native vegetation area,the bare spot effect of zokor-mound brought lower plant community height,coverage,aboveground biomass,underground biomass,total biomass and richness index,while the edge effect of zokor-mound brought higher plant height,aboveground biomass and species richness.The height and aboveground biomass of plant communities were mainly controlled by forbs in the bare spot area,while in the edge area,the community height and aboveground biomass were mainly controlled by the Gramineae.This indicated that the edge effect of zokor-mound could compensate for the loss of biomass and diversity caused by bare spot effect.3.The bare spot effect of zokor-mound changed the vertical distribution pattern of soil total and available nutrients,while the edge effect of zokor-mound had no effect on the vertical distribution pattern of soil nutrients.The bare spot effect and edge effect of the new-born mounds on soil nutrients in Luqu County and Xiahe County were similar.Compared with the soil nutrient contents of original grassland,the effect of bare spot effect on the soil nutrient contents in 0-10 cm and 10-20 cm layers was inconsistent,which showed that the total nutrient(organic carbon,total nitrogen and total phosphorus)in 0-10 cm layers decreased significantly,and the available nutrients(nitrate nitrogen,ammonium nitrogen,available phosphorus)in 0-10 cm soil layer,total nutrients(organic carbon,total nitrogen,total phosphorus)and available nutrients(nitrate nitrogen,ammonium nitrogen,available phosphorus)in 10-20 cm soil layer all increased significantly.The edge effect of zokor-mound caused the total nutrient(organic carbon,total nitrogen)and available nutrients(nitrate nitrogen,ammonium nitrogen,available phosphorus)in the two soil layers 0-10 cm and 10-20 cm in the edge zone were higher than those in the native vegetation zone,indicated that the edge effect of zokor-mound had the effect of enriching soil nutrients.4.The bare spot effect and edge effect of plateau zokor mounds changed the correlation between vegetation and some soil nutrients.Vegetation height,coverage,productivity and richness were mainly affected by soil nutrient concentrations in 0-10 cm soil layer in Luqu County and Xiahe County.Compared with the control area,bare spot effect and edge effect changed the correlation between some soil nutrients and plant community characteristics in 0-10 cm and 10-20 cm soil layers,but the latter was weaker.The bare spot effect of zokor-mound produced the height and productivity of community were positively correlated with organic carbon and total nitrogen.The edge effect of zokor-mound produced plant community height,coverage and productivity were significantly positively correlated with organic carbon,total nitrogen,nitrate nitrogen and ammonium nitrogen.In conclusion,the responses of plant community height,coverage,aboveground biomass,underground biomass,total biomass and species richness to bare spot effect and edge effect of plateau zokor mound were consistent in different sites.The responses of organic carbon,total nitrogen,nitrate nitrogen,ammonium nitrogen,total phosphorus and available phosphorus in 0-10 cm soil layers of different locations to nude spot effect and marginal effect of mound were consistent.So as the total nitrogen,nitrate nitrogen,ammonium nitrogen and available phosphorus in 10-20 cm soil layer.The bare spot effect affected the soil by changing the vertical distribution pattern of soil nutrient content.The edge effect resulted in the enrichment of total and available nutrients in the marginal zone.