白刺灌丛对土壤空间变异特征的影响及其驱动因素

As an indispensable part of terrestrial ecosystems,deserts have very fragile habitats,and the vegetation in this area is mostly patchy in distribution due to the limitation of the resource environment,and the established species are mainly dominated by tufted and arid plants,which play a significant role in regulating the regional climate,maintaining soil and water resources,and providing habitats for a large number of species.In this study,we analyzed the spatial variability of carbon(C),nitrogen(N),and phosphorus(P)in the soil of white thorn scrub in the desert grassland area based on nine sample sites in Yanchi County,Ningxia,Inner Mongolia,and Gansu,with widely distributed white thorn(Nitraria tangutorum)scrub as the object of the study,and analyzed the characteristics of carbon,nitrogen,and phosphorus(P)in the soil of white thorn scrub in the desert grassland area using the method of large-scale sample survey and indoor mathematical model simulation.The study analyzed the spatial variability of carbon(C),nitrogen(N)and phosphorus(P)in white thorn scrub soils in the desert grassland area,explored the mechanism of white thorn scrub's influence on soil C,N and P elements,and revealed its main driving factors.The main results of the study are as follows: (1)Precipitation and latitude were the key factors influencing the leaf stoichiometric characteristics of white thorn.Root P and N/P were significantly negatively and positively correlated with longitude(p<0.05),C/N was significantly negatively correlated with latitude(p<0.05),and N and N/P were negatively correlated with altitude at the 0.001 and 0.05 levels,respectively.Leaf N content and C/N were highly significant positively and negatively correlated with latitude(p<0.001),respectively.Altitude and MAP were the key factors affecting the stoichiometric characteristics of white spurge roots.White spurge root P and N/P were negatively and positively correlated with longitude at the 0.05 level,root C/N was negatively correlated with latitude at the 0.05 level possibly related to precipitation,and root N and N/P were negatively correlated with elevation at the 0.001 and 0.05 levels,respectively. (2)Mean annual precipitation,latitude and longitude were the main environmental factors affecting herb stoichiometric characteristics.Herb C content within the thicket was significantly negatively correlated with longitude(p<0.05),N content and C/N were highly significant positively and negatively correlated with latitude(p<0.01),N/P was significantly positively correlated with latitude(p<0.05),N content and C/N were significantly negatively correlated(p<0.05)and highly significant positively correlated(p<0.01)with altitude,P content was significantly negatively correlated with mean annual precipitation(p<0.05),and C/P and N/P were positively correlated with mean annual precipitation at the 0.05 level.The N content and C/N of the herb outside the scrub were significantly positively and negatively correlated with longitude(p<0.01),and N content,C/P,and N/P were positively correlated with mean annual precipitation at the 0.001,0.05,and 0.01 levels,respectively.In the case of sufficient precipitation,element P was the main element limiting herbaceous growth. (3)Soil C and N in general decreased gradually with the increase of soil depth,and P content did not have a uniform pattern in soil depth.The soil C,N and P stoichiometries in the thicket were higher than those outside the thicket,and the C source,organic matter decomposition rate and mineralization rate of the soil in the thicket were low compared with those outside the thicket.Midwest>North,and C/P and N/P were North>South>Midwest.Temperature is an important factor affecting soil C.Soil C,N,and P contents in the thicket were all more deficient,and the degree of deficiency was N>C>P. (4)Longitude and latitude are the main environmental factors affecting soil stoichiometric characteristics.Soil C/P and N/P within the scrub were all highly significantly negatively correlated with altitude(p<0.01),and N/P was significantly negatively correlated with MAT(p<0.05).Elevated temperature was unfavorable to soil N accumulation,and at higher temperatures soil P elements were more easily lost than N elements,and N reduction helped to increase the soil P content within the white thorn scrub,and the degree of influence of temperature on soil C,N,and P elements was P>N>C.Soil C content outside the scrub was highly significantly positively correlated with MAT(p<0.01),and soil N content was positively correlated with longitude and MAP at the 0.01 and 0.001 levels,and P content was significantly negatively correlated(p<0.05)and highly significantly positively correlated(p<0.01)with longitude and elevation,respectively.Within a certain temperature interval,the increase in temperature favored C accumulation. In summary,there was obvious spatial heterogeneity in the C,N and P stoichiometric characteristics of desert grassland,and N and P elements were the main elements limiting the growth of scrub sand pile vegetation.Therefore,it is important for ecological protection to carry out regional ecosystem vegetation restoration according to local conditions.