3种不同机械沙障设置后期对沙丘植被和土壤粒度与水分的影响

Influence of Three Different Mechanical Sand Barriers to Sand Dune Vegetation,Soil Particle Size and Moisture Content in Late Stage

选择设置了12年的塑料网格沙障、麦草沙障和黏土沙障进行长期定位观测,以流动沙丘作为对照,对机械沙障内的植被、土壤机械组成及土壤水分特征进行研究,结果表明:机械沙障内的植被盖度显著增加,多样性指数麦草沙障和黏土沙障显著增加、塑料网格沙障减小,群落结构由耐旱植物向短命植物演替;不同的机械沙障均能增加表层土壤中的黏粒含量,但塑料网格沙障与黏土沙障内土壤的黏粒含量增加显著,麦草沙障增加不显著;不同机械沙障的建立均使得土壤的含水量下降,塑料网格沙障、麦草沙障和黏土沙障内的土壤含水量比流动沙丘分别降低了41.29%、5.05%、31.78%,沙障内土壤水分的季节性变化更加稳定;受机械沙障的影响,降水的入渗深度及入渗速率均减小,使得土壤水分的再分配过程产生明显的滞后性。机械沙障设置后期虽然引起土壤水分含量减少,但它带来的防风固沙效益不容忽视。综合考虑其成本、效益及时效性等因素,认为在沙区应该推广塑料网格沙障。

The paper studied the characteristics of vegetation,soil mechanical composition and soil moisture within the mechanical sand barrier by selecting 12-year plastic-mesh sand barrier,wheat-straw sand barrier and clay sand barrier for long-period observation and taking moving dune as a check. The outcomes show that a) the vegetation coverage within the sand barriers is significantly increased,the diversity indexes of wheatstraw and clay sand barriers are significantly increased and that of plastic-mesh sand barrier decreased,and the succession of community structure is from drought-enduring plant to ephemeral plant; b) the different mechanical sand barriers can increase the clay content of surface soil,while the clay content of soil within the plastic-mesh and clay sand barriers is remarkably increased,but the increase of wheat-straw sand barrier is not remarkable; c) the building of different mechanical sand barriers make the moisture content decreased,the moisture contents of plastic-mesh,wheat-straw and clay sand barriers are decreased 41.29%,5.05% and 31.78% respectively comparing with that of moving dune and the seasonal variation of soil moisture of sand barriers is more stable and; d) due to the influence of mechanical sand barrier,the infiltration depth and rate of precipitation are all decreased,making the redistribution process of soil moisture obvious hysteresis. Although the mechanical sand barrier in late stage has reduced the moisture content,the benefits of windbreak and sand fixation cannot be ignored.Comprehensively considering the factors of cost,benefit and timeliness,plastic-mesh sand barrier should be popularized in sandy area.