不同演替状态下高寒草甸土壤物理性质与植物根系的相互关系

采用空间代时间的方法,以高寒嵩草草甸不同退化演替状态土壤物理性质(土壤机械阻力、温度、湿度)为变量,探讨高寒草甸不同退化阶段土壤物理性质同植物根系生长特质的相互关系。结果表明:高寒嵩草草甸根系分布具有明显的"V"型垂直构型特征;高寒嵩草草甸根系以细根为主,直径0.5 mm的根系占全剖面根系总长的90.8%—93.6%。土壤紧实度和土壤湿度与植物根系直径细化具有显著的正相关关系(P0.05);土壤温度与根系细化之间具有显著的负相关关系(P0.05),且其对高寒嵩草草甸根系生长特性形成的贡献率最高,说明高寒嵩草草甸植物根系生长构型特征的主控因子为温度。高寒嵩草草甸根系细化及表聚现象与土壤物理性质之间具有一定程度的互馈效应。低温、高紧实度和较高的土壤湿度有助于形成高密度和细根构型的草毡表层,这种土壤根系构型也是高寒草甸植物群落为适应放牧干扰及恶劣环境的应激性改变。该发现对明晰草地退化演替过程中生态系统构件对外界干扰改变的响应和适应过程及为制定合理有效的退化高寒草甸恢复措施提了供理论依据。

Relationship between plant roots and physical soil properties in alpine meadows at different degradation stages

The aim of the studies is to investigate the relationship between properties of plant roots and physical soil in alpine Kobresia humilis meadows at different degradation stages,using the spatial scale instead of temporal scale. The results showed that: the principal part of construction of root system in the alpine Kobresia meadow was slender roots, meanwhile the roots obviously distributed with the configuration of "V" type from the ground to the bottom, and the diameter of the root system was mostly less than 0.5 mm (90.8%-93.6% of total root length). There was a significant positive correlation between soil compactness, soil moisture, and plant root diameter refinement. While, there was a negative correlation between soil temperature and root attenuation, that means soil temperature was the major contributor to establish the root growth pattern, in other words the alpine Kobresia meadow was mainly temperature-controlled grassland ecosystem.Secondly, there was a interact effect on root attenuation, root aggregation, and the physical soil properties in the alpine Kobresia meadow. Low temperature, high compactness, and relatively high soil moisture were the contributors to form the high density and root configuration. The change of the root configuration is a positive response of plant communities to livestock grazing disturbance and the severe weather. Those findings provide a theoretical basis for explaining the response and adaptation to grassland degradation, and it is useful to formulate reasonable and effective restoration measures for degraded alpine meadows.