不同治沙措施对荒漠绿洲过渡带植物群落与土壤因子的影响

沙漠化是河西走廊荒漠绿洲过渡带土地退化的主要原因，科学合理的治沙措施能够有效控制风沙侵害，有助于植被-土壤系统的重建与恢复。多年来，治沙措施的研究主要集中在不同时间梯度下某种给定措施对植物群落及土壤的影响方面，对于同一时间段内不同类型措施产生的生态惠益尚缺乏足够认识。鉴于此，以流动沙地丘间地为对照，选取围栏封育+麦草沙障(Ge+Ws)、麦草沙障+人工梭梭(Ws+H)和尼龙沙障+人工梭梭(Nn+H)3种不同的治沙措施区为研究对象，通过群落学调查与土壤因子测定，研究了不同治沙措施影响下植物群落数量特征和土壤因子的变化规律与相互关系，并对各措施的生态效益进行了评价。结果表明：(1)植被方面，3种治沙措施影响下草本层和灌木层群落数量特征均呈增加趋势，其中Ge+Ws草本层恢复效果较佳，Ws+H和Nn+H灌木层恢复程度更明显；土壤方面，伴随植物群落的恢复，3种治沙措施均能大幅改善土壤全碳、全氮、有机质等主要养分，但同时对土壤水分带来负面效应，Ge+Ws、Ws+H及Nn+H的表层土壤含水量依次减少了37.99%、 31.37%和35.94%。(2)结构方程模型显示，治沙措施通过直接影响灌木和草本群落...

Effects of different sand control measures on plant communities and soil factors in the desert-oasis ecotone

Desertification is the main cause of land degradation in the desert-oasis ecotone of the Hexi Corridor. Scientific and reasonable sand control measures can effectively control wind-sand damage and then contribute to the reconstruction and restoration of the vegetation-soil system. For many years, research on sand control measures has focused on the impact of a given measure on plant communities and soil under different periods. There is still lack of sufficient understanding of the ecological benefits of different measures in the same period. In view of this, we took the inter-dune land of active sand dune (Asd) as a control, selected grazing exclusion+wheat straw sand barrier (Ge+Ws), wheat straw sand barrier+Haloxylon ammodendron plantation (Ws+H) and Nylon net sand barrier+Haloxylon ammodendron plantation (Nn+H) as the different treatments. The quantitative characteristics of plant communities and the changing laws and relationships of soil factors under different sand control measures were studied, and the ecological benefits of each measure were evaluated. The results showed that:(1) in terms of vegetation, the number of the herb layer and shrub layer communities under the three sand control measures showed an increasing trend. Among them, herb increased mostly in the Ge+Ws, while the shrub increased mostly in the Ws+H and Nn+H; In terms of soil, with the restoration of plant communities, the three sand control measures could greatly improve the main nutrients such as soil total carbon, total nitrogen, and organic matter, but at the same time had negative effects on soil moisture, the water content of the surface soil under Ge+Ws, Ws+H and Nn+H decreased by 37.99%, 31.37% and 35.94%, respectively. (2) The structural equation model showed that sand control measures indirectly changed soil factors by directly affecting shrub and herb communities. Increasing the number of shrub communities would significantly reduce soil moisture (P<0.001), but the negative impact of herb communities on soil moisture was not significant in Nn+H. Similarly, shrub communities were the main driving factor for soil nutrient increase, while the positive effect on soil nutrients only reached a significant level in Ge+Ws for herb communities (P<0.05). Under the influence of sand control measures, the shrub layer and the herb layer had a synergistic relationship and this relationship reached a significant level in the Ws+H (P<0.05) and Nn+H (P<0.01) regions where Haloxylon ammodendron was planted. (3) The advantage of Ge+Ws lies in the species diversity and productivity of herb communities. It is suitable for areas where native shrubs are colonized in active sand dunes; Ws+H and Nn+H can be constructing more stable and high-productivity shrub communities, especially the Nn+H which produces better ecological benefits and should be given priority.