干旱区生态环境知识资源中心

It is well documented that wind redistributes and transports soil resources in semiarid ecosystems. However, fewer studies have quantitatively linked wind erosion to detailed grain-size fractions and associated nutrient content in surface soil and windblown sediment. In this study, we examined ( 1) the effects of enhanced wind erosion on surface soil particle-size distribution and ( 2) carbon ( C) and nitrogen (N) characteristics of windblown sediments in a typical desert grassland of southern New Mexico. Our results show that surface soil has become noticeably coarser over a 2-year period. In particular, content of soil particles in the category of 250-500 mu m increased significantly, but soil particles in the fractions of 50-125 mu m and <50 mu m were significantly depleted. In addition to the enrichment of C and N in the windblown sediments, our results reveal that fine particles ( e. g., D < 50 mu m) were enriched to a much higher degree at height than C and N. Significantly, our results reveal that nearly 12% of total organic carbon (TOC) and 9% of total nitrogen (TN) were found in the particles with diameter < 50 mu m, which account for only 1-2% of the mass of windblown sediments. In this wind susceptible environment, our findings suggest that ( 1) significant soil texture change ( e. g., the loss of soil fines) driven by wind erosion could happen rapidly and soil fine particles ( e. g., silt and clay) may be depleted within a few years and ( 2) the loss of even a small fraction of fine particles may indicate a substantial depletion of soil C and N.