Spatial Heterogeneity of Soil Carbon and Nitrogen Contents and Isotopes in the Arid Valley-Mountain Forest Ecotone in the Upper Reaches of Minjiang River,China
[Objective]This study was aimed to explore the spatial heterogeneity of soil carbon(C)and nitrogen(N)cycling and its impact mechanisms of arid valley-mountain forest ecotone in the upper reaches of Minjiang River,and to provide a theoretical basis for scientific management in this region.[Method]A typical shrub forest of Quercus baronii was selected in the transition area between the arid valley and the mountain forest in the upper reaches of Minjiang River.Soil samples were sampled through a Latin hypercube sampling design,descriptive statistical characteristics,spatial heterogeneity,spatial similarity and correlation of soil C and N contents and their isotopes(δ13C and δ15N)were analyzed using a combination of classical statistics and geostatistical methods.[Result]The soil δ13C and soil δ15N of Quercus baronii shrub forest in the arid valley-mountain forest ecotone in the upper reaches of Minjiang River showed a weak and moderate spatial variability,respectively.Both soil δ13C and soil δ15N showed positive spatial autocorrelation,and the spatial aggregation of soil δ13C was higher than that of soil δ15N.The spatial heterogeneity of soil δ13C was dominated by structural factors,and the spatial heterogeneity of soil δ15N was jointly influenced by structural and stochastic factors.The spatial distributions of soil δ13C and soil δ15N were strongly similar,and were both strongly spatially correlated with soil C and N contents.Soil δ13C and soil δ15N were strongly correlated and were both directly or indirectly affected by soil moisture,C and N contents and C/N ratio.[Conclusion]The soil δ13C and δ15N showed different spatial variability but coupled relationship in the Q.baronii shrub forest in the arid valley-mountain forest ecotone in the upper reaches of Minjiang River.
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