高原鼠兔干扰对高寒草甸植物多样性与土壤养分间关系的影响

高原鼠兔干扰虽然能够改变高寒草甸植物多样性与土壤养分含量,但植物多样性与土壤养分间的关系对高原鼠兔干扰的响应尚不清晰。利用高原鼠兔有效洞口密度将高原鼠兔干扰程度划分为T_1(7个/625 m~2)、T_2(12个/625 m~2)、T_3(22个/625m~2)、T_4(38个/625 m~2)4个水平,运用RDA冗余分析法研究了高原鼠兔不同干扰程度下高寒草甸植物多样性与土壤养分间的关系。结果表明:随着高原鼠兔干扰水平的增加,优势种高山嵩草(Kobresia pygmaea)的重要值先增加后降低,而伴生种小花草玉梅(Anemone rivularis var.flore-minors)和莓叶委陵菜(Potentilla fragarioides)的重要值先降低后增加;当高原鼠兔干扰水平从T_1到T_2时植物多样性指数变化不显著,而高原鼠兔干扰程度超过T_2时则植物多样性指数具有降低趋势;土壤全氮和硝态氮含量随高原鼠兔干扰水平增加而降低,而土壤铵态氮含量则降低后增加,土壤有机碳和全磷先增加后降低;多样性指数与0—10cm土壤深度硝态氮、10—20cm土壤深度全钾间的相关性从T_1到T_3时为正相关,而到T_4时则变为负相关,而与0—10cm土壤深度全氮的相关性则表现T_1到T_3时为负相关,T_4时为正相关,与铵态氮间相关性只有T_1时为负相关,这说明高原鼠兔干扰改变了植物多样性与土壤养分间的关系,其变化阈值介于T_2和T_3。

The effect of plateau pika(Ochotona curzoniae) disturbance on the relationship between plant diversity and soil nutrients of alpine meadow

Although plant diversity and soil nutrients content can be affected by plateau pika disturbance, the relationships between plant diversity and soil nutrients of alpine meadows in response to plateau pika disturbance are still unclear. RDA redundancy analysis was used to determine the effect of plateau pika disturbance on the relationship between plant diversity and soil nutrients of alpine meadow by using the active burrow entrance density of plateau pika to substitute for the disturbance levels of plateau pika, in which the disturbance consisted of four levels with density of T₁ (7 active burrows/625 m²), T₂ (12 active burrows/625 m²), T₃ (22 active burrows/625 m²) and T₄ (38 active burrows/625 m²). This study showed that the important value of Kobresia pygmaea, dominant plant, firstly increased and then decreased with the increase of plateau pika disturbance level, while the important value of Anemone rivularis var. flore-minors and Potentilla fragarioides, main associate plants, firstly decreased and then increased with the increase of plateau pika disturbance level. The plant diversity index increased when the plateau pika disturbance increased from T₁ level to T₂ level, and showed a decreasing trend when the plateau pika disturbance exceeded T₂ level. Soil total nitrogen and nitrate nitrogen showed a decreasing trend, and ammonium nitrogen firstly decreased and then increased as the plateau pika disturbance increased, while soil organic carbon and total phosphorus firstly increased and then decreased in the increasing process of the plateau pika disturbance. RDA analysis results showed that the correlation relationships between plant diversity index and nitrate nitrogen at 0-10cm soil depth and potassium at 10-20cm soil depth was significantly positive when plateau pika disturbance ranged from T₁ level to T₃ level, and it became negative when plateau pika disturbance was T₄ level, while the correlation relationships between plant diversity index and total nitrogen at 0-10cm soil depth was significantly negative when plateau pika disturbance increased from T₁ level to T₃ level, and it became positive when plateau pika disturbance reached to T₄ level. The relationship between plant diversity index and ammonium nitrogen at 0-10cm soil depth was negative correlation at T₁ level environment and it became positive at T₂, T₃, T₄ levels. These results indicated that the plateau pika disturbance changed the relationships between plant diversity index and soil nutrients of alpine meadow, and the sensitive disturbance of plateau pika on relationships between plant diversity index and soil nutrients was T₂ level and T₃ level.