青藏高原高寒草甸不同放牧方式下土壤粒徑分形特征

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Abstract：To evaluate the impact of grazing practices on soil particle size distribution in alpine meadows of the Qinghai-Tibet Plateau based on fractal theory，four grazing practices were carred out：yak grazing，Tibetan sheep grazing，mixed yak and Tibetan sheep grazing，and no grazing. Soil particle size distribution was measured using alaser particle size analyzer，and the responses of soil particle composition and fractal characteristics to various grazing practices were analyzed to reveal spatial distribution paterns of soil particle sizes under diferent grazing regimes.The results showed that soil particle composition in all sample plots was primarily composed of silt，fine sand，and very fine sand，with sand particles accounting for the highest volume fraction （ 4 9 . 3 % - 6 7 . 2 % ），followed by silt （ 2 6 . 1 % - 4 0 . 8 % ） ，and clay representing the lowest fraction （ 5 . 0 % - 1 0 . 0 % ） . Surface soils in mixed grazing plots of yak and Tibetan sheep displayed higher fine particle content and single fractal dimensionbut significantly lower bulk density compared to other treatments.Correlation and principalcomponent analysis revealed that the single fractal dimension was significantly positively correlated with clay，silt，and organic carbon，while exhibiting a significant negative corelation with sand. In conclusion， at moderate grazing intensity，mixed yak and Tibetan sheep grazing in alpine meadows of the Qinghai-Xizang Plateau can promote uniform soil particle distribution，maintain stable soil structure，and improve soil texture.

Key words： Qinghai-Tibetan Plateau；Livestock assembly；Soil particle composition； Single fractal

青藏高原是世界上最高的高原，也是我國主要的生態(tài)屏障，總面積為 ，其中高寒草甸占 3 5 % 以上。（剩余11935字）