高寒沙区两种典型固沙植物改良土壤的策略

植被恢复与重建是退化土地生态修复的重要途径,植物与土壤环境的关系一直是热点科学问题,但对高寒沙区尚缺乏系统性的研究。为探明不同沙生植物对高寒沙地土壤的改良策略,以青海共和盆地中间锦鸡儿(Caragana intermedia)和乌柳(Salix cheilophila)两种典型固沙植物为研究对象,通过对比细根分布规律分析其环境适应性,结合林地土壤物理性质、有机碳含量和土壤含水量等要素,分析两种植物对土壤的改良作用。结果表明,(1)两种植物的细根主要集中在0-60 cm土层,中间锦鸡儿水平方向分布更多,且细根平均生物量密度和有机碳含量都高于乌柳。(2)乌柳人工林各深度土壤有机碳密度均高于中间锦鸡儿,其累计百分比在0-40 cm土层较高,中间锦鸡儿在40-120 cm较高。(3)两种人工林的土壤容重、最大持水量和毛管持水量均值差异不显著。中间锦鸡儿林地土壤容重在0-40 cm土层大于乌柳,在40-120 cm小于乌柳;其最大持水量和毛管持水量在0-60 cm小于乌柳,在60-120 cm大于乌柳。(4)两种人工林土壤含水量和土壤温度都呈表层高,随土壤深度递减趋势。乌柳林地各深度土壤含水量均高于中间锦鸡儿,土壤温度均低于中间锦鸡儿。研究表明,中间锦鸡儿的环境适应性和固沙能力较强,倾向于深层土壤改良和固碳策略;乌柳人工林的固碳作用和涵养水源能力较强,倾向于表层土壤改良和固碳策略;同时,两种人工林都倾向于表层保水的策略。该文通过对比分析不同沙生植物改良土壤的策略,为长期研究高寒沙区生态修复与优良固沙植物筛选等工作提供理论依据。

Two Typical Sand Binder Strategies for Improving Soil in Alpine Sandy Land

Vegetation restoration and reconstruction is an important approach to ecological restoration of degraded land,and the relationship between plants and soil environment has always been a hot scientific issue.However,the systematic research on the alpine sandy land is still lacking.In this study,the Caragana intermedia and Salix cheilophila in Gonghe basin of Qinghai were used as research objects to explore the improvement strategies of different sandy plants on the alpine sandy soil.The environmental adaptability is analyzed by comparing the distribution of their fine roots.And the effects of the two-plants on soil improvement were analyzed through the physical properties of soil,soil organic carbon content and soil moisture content.The results,(1)The fine roots of the two plants are mainly concentrated in the 0-60cm soil layer.The Caragana intermedia has more fine roots in the horizontal direction,and its average biomass density of fine roots and organic carbon content were more than the Salix cheilophila.(2)The soil organic carbon density of the Salix cheilophila plantation is more than the Caragana intermedia in all depths.And the Salix cheilophila’s soil organic carbon fraction is higher in the 0-40cm soil layer,the Caragana intermedia is higher in the 40-120cm soil layer.(3)There were no significant differences in soil bulk density,maximum water capacity and capillary water capacity between the two plantations.The soil bulk density of the Caragana intermedia is greater than the Salix cheilophila in the 0?40 cm soil layer,and it is less than the Salix cheilophila in the 40?120 cm soil layer.The maximum water capacity and capillary water capacity of the Caragana intermedia is less than the Salix cheilophila in the 0?60 cm soil layer,and it is greater than the Salix cheilophila in the 60?120 cm soil layer.And(4)the soil moisture content and soil temperature of both plantations were higher in the surface layer and decreased with soil depth.The soil moisture content at all depths of the Salix cheilophila is higher than the Caragana intermedia,and it’s soil temperature is lower than the Caragana intermedia.Studies have shown that,the Caragana intermedia has strong environmental adaptability and sand-fixing ability,and it tends to improve deep soil and carbon fixation in deep soil.The Salix cheilophila plantation has strong carbon fixation and water conservation capacity,and it tends to improve the surface soil and carbon fixation in surface soil.At the same time,both plantations favor strategies for retaining surface soil moisture.By comparing and analyzing the soil improvement strategies of different sandy plants,this paper provides a theoretical basis for the long-term research on ecological restoration and selection of fine sandfixing plants in alpine sand areas.