Soil nutrient stoichiometry on linear sand dunes from a temperate desert in Central Asia

Abstract

Soil nutrient stoichiometry can influence the biodiversity, vegetation productivity, and biogeochemical cycles in terrestrial ecosystems. However, the soil nutrient status, distribution patterns, and driving factors on sand dunes in modern deserts were still unclear. The soil C, N, P, and K contents in 65 plots across two continuous linear sand dunes (220 m × 110 m) located in the Gurbantunggut Desert, a typical temperate desert in Central Asia, were investigated by the traditional statistical, geostatistical, and structural equation modeling (SEM) techniques. Results indicated that soil C, N, and P contents were low and presented remarkable interactions with each other. The order of soil nutrient deficiency in the sand dunes was C > N > P > K, in which soil C exhibited a higher accumulation rate than N and P based on allometric analysis. Soil C, N, P, and their ratios to K exhibited an obvious U-shaped curve opposite to the shape of the sand dune, had strong spatial dependence (structural variance ratios: 81.4–94.3%), and presented evidently longitudinal zonal distribution patterns along the sand dunes. Pearson's correlation analysis and canonical correspondence analysis demonstrated that the topographic (slope position, relative height, convexity, and curvature), vegetation (herbaceous richness, abundance, coverage and biomass, and deep-rooted small shrubbery), soil abiotic (pH, electronic conductivity, and soil water content), and soil biotic (i.e., biological soil crust) factors interacted with each other and were significantly correlated with most soil stoichiometric parameters. The SEM analysis further demonstrated that the topography was the most direct driving factor influencing soil C, N, and P and their ratios to K on sand dunes. The results revealed that sand dune fixation and lowering promoted the formation of a stable and sustainable soil–plant relationship in temperate deserts of Central Asia.