灌草立体配置对退化草地土壤水分和养分的影响

Influences of shrub-grass patterns on soil water and nutrient of grassland

【目的】比较灌草立体配置模式下3种不同生境的土壤水分、养分和植物根系相关参数的差异,探究灌草立体配置30年对退化草地土壤水分和养分以及植物根系的影响,为黄土高原水土保持和生态恢复提供理论依据。【方法】以位于黄土高原云雾山国家草原自然保护区种植30年的人工柠条和野山桃搭配灌丛带样地为研究对象,采集灌丛带内部、灌丛带边缘和灌丛带外部不同土层的土样和植物根系,比较3种位置下土壤水分、养分含量和植物根系特征的差异,并分析了根长与土壤水分和养分含量的相关性。【结果】在0~80 cm土层,灌丛带内部的土壤含水量明显高于灌丛带边缘和灌丛带外部。在0~80 cm土层,随着土层深度增加,灌丛带3个位置土壤全氮、碱解氮和有机碳含量均呈下降趋势,而全磷含量变化不明显;在同一土层,灌丛带内部的全氮、碱解氮和有机碳含量均明显高于灌丛带边缘和灌丛带外部。在灌丛带内部、灌丛带边缘和灌丛带外部3个位置,植物根系生物量呈减小的趋势。从垂直分布来看,灌丛带内部、灌丛带边缘和灌丛带外部0~15 cm土层的植物根系生物量分别占0~40 cm土层植物根系生物量的90.86%,90.79%,92.91%,说明植物根系生物量主要集中分布于0~15 cm土层。3个取样位置中,灌丛带内部植物根长、根表面积和根体积均最大。相关性分析表明,灌丛带植物根长与0~20 cm土层的土壤含水量,0~40 cm土层土壤有机碳和全氮、0~80 cm土层碱解氮均呈显著或极显著正相关。【结论】在黄土高原退化草地上进行灌草立体配置可以促进植物根系生长,提高土壤水分和养分含量,有利于退化草地的恢复。

【Objective】By comparing the differences of soil water,nutrient and plant root in three different habitats under shrub-grass patterns,the effects of shrub-grass patterns over 30 years on soil water,nutrient and plant root in degraded grassland were explored to offer references for soil and water conservation and ecological restoration on the Loess Plateau.【Method】The shrub sample sites of 30 years old Caragana korshinskii and Amygdalus davidiana in the Yunwu Mountain National Nature Reserve were selected and soil samples and plant roots were collected from different soil layers inside,near edge and outside of the shrub.The differences in soil water and nutrient and root characteristics were compared,and the relationships between root length and soil water and nutrient were analyzed.【Result】In the 0-80 cm soil layer,soil water content inside shrub was significantly higher than the edge and outside.With the increase of soil depth,the contents of total nitrogen,alkali-hydrolyzable nitrogen and organic carbon in the three locations showed decreasing trend,while total phosphorus had no significant change.In same soil layer,contents of total nitrogen,alkali-hydrolyzable nitrogen and organic carbon inside shrub were significantly higher than the edge and outside.The root biomass showed a decreasing trend of inside>edge>outside.From vertical distribution,root biomasses of inside,near edge and outside of shrub in the 0-15 cm soil layer accounted for 90.86%,90.79%and 92.91%of the total root biomass in the 0-40 cm soil layer,indicating that the root biomass mainly distributed in the 0-15 cm soil layer.The biomass,length,surface area and volume of roots inside shrub were the largest among the three sampling locations.Correlation analysis showed that the root length in shrub was significantly or extremely significantly positively correlated with soil water in the 0-20 cm soil layer,organic carbon and total nitrogen in the 0-40 cm soil layer,and alkali-hydrolyzable nitrogen in the 0-80 cm soil layer.【Conclusion】The shrub-grass patterns on the Loess Plateau would promote root growth,increase soil water and soil nutrient content,and be conducive to restoration of degraded grassland.