Effect Of Plateau Zokor On Duration Of Soil Carbon And Nitrogen Concentration In Alpine Meadow

The plateau zokor(Eospalax fontanierii)is a small subterranean mammal commonly found in alpine meadows of the Qinghai-Tibetan Plateau.This species seriously affects the healthy and stable development of the alpine meadow ecosystem by foraging on plant belowground biomass,building tunnel systems and creating zokor mounds.There are a large number of zokor mounds nested in alpine meadow,the easy formation of runoff and lack of vegetation on mounds not only resulted in mound effect,but also enabled the plants adjacent mound to receive more light and soil resources(water and nutrients),and this is beneficial to the growth of those plants,resulting in a higher plant biomass on areas at adjacent mound.Therefore,the area with plateau zokor can be classified in mound,edge effect zone(edge area)and stay away from the edge effect zone(control area).Consequently,the effects of plateau zokor on soil carbon and nitrogen include mound effect and edge effect,through comapring in carbon and nitrogen among mound,edge area and control area.Plateau zokor widely distributes territorially and patchily on alpine meadows.Thus,results of the effects of plateau zokor on soil carbon and nitrogen in alpine meadows can also be affected by vegetation types,meteorological and geomorphic factors.However,most of the published studies are constricted to one site,moreover,previous studies either either do not pay attention to the difference of soil carbon and nitrogen between the edge area and the vegetation area,or ignore the relationship between the edge effect and the age of the zokor mound.The alpine meadows at Tianzhu County,Maqu County and Xihe County in Gansu Province were selected to investigate the effects of plateau zokor on soil carbon and nitrogen concentrations.This study clarified the influence of plateau zokor on soil carbon and nitrogen by comparing the differences among mound,edge area,and control area,and determined the temporal validity of mound effect and edge effect though analyzing the relationship between mound age and soil carbon and nitrogen concentration to.The main conclusions are as follows:1.There were general patterns concerning the effect of plateau zokor's mound effect on soil bulk density and water content;the edge effects of on soil water content were also similar in there sites,but edge effect on soil bulk density is site-dependentNo matter when the data from five sites were analysed together,or the data from each site was analyzed separately,the soil bulk density and water content of the zokor mound were significantly lower than those of the control area.Therefore,there were general patterns concerning the mound effect in relation to soil bulk density and water content.There was no difference in the soil bulk density between the edge area and the control area at Tianzhu and Maqu,while it was lower in edge area than in control area in Xiahe.Therefore,there were no general patterns concerning the edge effect in relation to soil bulk density.In addition,the edge effect had no significant effect on soil water content at the three sites.2.There were general patterns concerning the effect of plateau zokor's mound effect and edge effect on soil total carbon and organic carbon concentrationThe soil total carbon and soil organic carbon concentrations were lower in the mound and higher in the edge soil than those in control area,and these results consistent among the three sites.Therefore,there were general patterns concerning the mound effect and edge effect in relation to soil total carbon and soil organic carbon concentrations.However,the difference of inorganic carbon concentrations between edge area and control area differed among the three sites.The soil inorganic carbon was not significantly different among edge area and the control area at Xiahe,while it was lower in the edge area than in the control area at Maqu and Tianzhu.3.There were general patterns concerning the effect of plateau zokor's mound effect and edge effect on soil total nitrogen,inorganic nitrogen and nitrate nitrogen concentration,while their effects on ammonium nitrogen concentration were site-dependentThe soil total nitrogen in the control area was higher than that in mound,and lower than that in the edge area,and the inorganic nitrogen and nitrate nitrogen concentration in edge area and mound were both higher than those in control.These results indicated that the responses of soil total nitrogen,inorganic nitrogen and nitrate nitrogen to mound effect and edge effect had general patterns.However,the responses of ammonium nitrogen concentration to edge effect were site-dependent.The ammonium nitrogen concentration was higher in the edge area than in the control area,and lower in edge area than in mound at Maqu and Tianzhu,whereas the ammonium nitrogen concentration was higher in mound than in the edge area and control area at Xiahe.4.Inter-annual variations trend of soil total carbon and organic carbon concentration in mound and edge area were similar,but the time effectiveness of the mounds effect and edge effects on soil total carbon and organic carbon were different among study sitesWith the increase of mound age,soil total carbon and organic carbon concentration of mound increased,which showed no difference with the control area in the third year;while the soil total carbon and organic carbon concentration of edge area first increased and then decreased,and there was no significant difference with the control area in the fifth year.However,soil inorganic carbon concentrations in mound and edge area were both not related to the mound age.Thus,there were time effectiveness about the mound effect and edge effect on soil total carbon and organic carbon.However,time effectiveness of mound effect and edge effect were site-dependent.The time effectiveness of mound effect in Tianzhu,Xiahe and Maqu was 3,4 and 5 years,respectively,while the time effectiveness of edge effect in Tianzhu was 4 years,while that in Maqu and Xiahe was 5 years,which indicating that the time effectiveness of mound effect and edge effect on soil total carbon and organic carbon was site-dependent.5.Inter-annual variations trend of soil nitrogen concentration(total nitrogen,inorganic nitrogen,ammonium nitrogen and nitrate nitrogen)in mound and edge area were similar;but the time effectiveness of the mounds effect on soil nitrogen were different among three study sitesWith the increase of the mound age,the total nitrogen concentration in the soil of the mound increased gradually,reaching the level of total nitrogen concentration in the control area in the second year;the total nitrogen concentration in the soil of the edge area increased first and then decreased,showing no difference between control area in the fifth year.As the mound age increased,soil inorganic nitrogen,ammonium nitrogen and nitrate nitrogen concentration of mound were all decreased,and inorganic nitrogen and ammonium nitrogen concentrations of mound showed no difference from control area in the 5th year,while the nitrate nitrogen showed no difference from control area was in the 3rd year.Soil inorganic nitrogen,ammonium nitrogen and nitrate nitrogen concentrations of edge area decreased with the increase of mound age,and the soil inorganic nitrogen and ammonium nitrogen had no significant difference between the edge area and the control area in the 3rd year,while nitrate nitrogen concentration showed no difference between the edge area and the control area in the second year.Thus,there were time effectiveness concerning of mound effect and edge effect on soil nitrogen,while they were site-dependent.The time effectiveness of mound effect on soil total nitrogen in Tianzhu,Xiahe and Maqu was 3,4 and 5 years,respectively.The time effectiveness of mound effect on soil inorganic nitrogen and ammonium nitrogen in Tianzhu County and Maqu were 5th year,while it was 4 years in Xiahe;the time effectiveness of mound effect on soil nitrate nitrogen was 4 years in Tianzhu County and Xiahe County,and it was 5th year in Maqu.