植被根系及其土壤理化特征在高寒小嵩草草甸退化演替过程中的变化

以野外样地调查和室内分析法研究了不同退化演替阶段高寒小嵩草草甸的植被根系空间变化和土壤环境因子间的关系。结果表明,不同退化演替阶段高寒小嵩草草甸群落植被根系和蕴育植被根系的土壤量发生了明显的变化。特别是0~10 cm土层的植被根系在重度退化阶段显著高于其它退化演替阶段（P〈0.05）,而蕴育植被根系的＂载体＂量在重度退化阶段显著低于其它退化演替阶段（P〈0.05）,根土比（根和土的重量比）明显高于其它退化演替阶段（P〈0.05）;随着退化演替阶段的进行,高寒小嵩草草甸群落物种数、地上部分、植被根系锐减,群落结构和功能明显发生变化;不同退化演替阶段,植被根系（0~40 cm）的垂直分布、根土比与土壤容重、土壤含水量以及土壤中N、P含量存在一定的相关性;不同退化演替阶段高寒小嵩草草甸土壤理化特性的变化影响草地群落地上部分和植被根系;土壤的稳定性是草地生产稳定和恢复的重要因素,在评价与改良退化草地时,要充分了解土壤的退化程度。在高寒草甸地下根系取样方法难以统一,而且土壤表层根系和土壤很难难以分离,加之根系采样破坏性大、工作量大,根土比可能是指示高寒草甸退化程度相对可靠的量化指标。

Vegetation roots and soil physical and chemical characteristics in degeneration succession of the Kobresia pygmaea meadow

The methods of field survey and experiment analysis were applied to detect the relationship between the spatial changing of vegetation roots and soil environmental factors under different degeneration succession in an alpine meadow.The experiment plots were located in the headwater region of Yangtze and Yellow Rivers.The results showed that the obvious change of roots distribution in the Kobresia pygmaea meadow community,soil quantity which cultivates roots under different degeneration succession in an alpine meadow.Especially the roots and ratio roots to soils at 0-10 cm soil layer were the greatest（P0.05）,and the lowest in the heavy degradation（P0.05）;The plant species,community aboveground biomass and vegetation roots were shown to decrease quickly,and the plant community structure and function were changed with increased degradation levels;The effects of soil bulk density,soil moisture,N,and P contents on vertical distribution of vegetation roots（0-40 cm） and ratio roots to soils under different degeneration succession were more significant;The soil physical and chemical characteristics were influenced by disturbance（grazing） to change the grassland community biomasses,vegetation roots at different degeneration succession in an alpine meadow.The soil stability is an important factor to keep the stability of grassland production and to recover of degraded grassland.In order to evaluation and using suitable measure to ameliorate the degraded grassland,we need to understand the degraded degree of the soil and the main factors causing the degradation.Ratio of roots to soils is relatively reliable quantified index to indicate degraded level in alpine meadow;while it is difficult to sample roots,separate soils and roots in alpine meadow.