川西高寒灌丛草地不同海拔梯度土壤化学计量特征

Soil Stoichiometric Characteristics of Alpine Shrub Meadow at Different Elevations,Western Sichuan

【目的】阐释川西高寒灌丛草地生态脆弱区各海拔梯度对土壤养分及化学计量特征的响应规律,为高寒山地生态系统的保护以及植被恢复与重建提供理论支持。【方法】在四川省甘孜州折多山东坡选取了3 400,3 600,3 800,4 000,4 200 m 5个海拔梯度,测定各海拔范围内0~20,20~40,40~60 cm各层土壤的养分含量,分析不同海拔梯度土壤化学计量比的垂直分布特征。【结果】土壤有机C、全N、C/P和N/P在海拔为3 400~3 800 m时呈现上升趋势,在3 800 m处达到最大值后又逐渐下降,整体呈"倒V型"变化;土壤全P、N/K和P/K随海拔的升高逐渐上升;土壤全K含量除在海拔3 600 m处之外,都随海拔的增加逐渐降低;C/N和C/K则随海拔的上升大致呈现增加的趋势。土壤有机C和全N显著相关(P<0.05),全N和全P显著相关(P<0.05);海拔与土壤全P和C/K呈现极显著正相关(P<0.01),和土壤全K呈现显著负相关(P<0.05),和土壤N/K、P/K呈显著正相关(P<0.05);受海拔及植被类型影响,高海拔地区土壤有机C和全N含量明显高于低海拔地区;C/P和N/P在一定程度上受有机C和全N的影响,而C/K、N/K和P/K受全K含量的影响较大;各化学计量比在不同海拔梯度的平均值表明植被类型对土壤C/N/P的影响较大,从而导致土壤碳氮磷的空间变异性较大。【结论】土壤有机C和全N含量具有明显的表聚作用,因此,加强高寒灌丛草地土壤的保护对折多山的植被修复和重建具有重大意义。

【Objective】The aim of the study was to explore the soil nutrients and stoichiometric traits ofalpine shrub meadow at different elevations of western Sichuan and to provide theoretical references forvegetation restoration and reconstruction in this region.【Method】Soil samples of three layers （0-20,20-40,40-60 cm） were collected from five elevations （3 400,3 600,3 800,4 000 and 4 200 m） in theeastern part of Zheduo mountain located in Ganzi region of Sichuan province.【Result】Soil organicC,totalN,C/P and N/P increased from 3 400 m to 3 800 m and peaked at 3 800m, then decreased gradually.The overall change tendency was like an ＂inverted V shape＂. Besides,the totalP,N/K and P/K in原creased gradually with and increase in altitude. The total K decreased leisurely with altitude except for3 600 m. Conversely,both C/N and C/K showed an increase trend with increasing altitude. In addition,there was a significant correlations between soil organic C and total N. and between N and P. Many soilparameters,likeP,C/K,N/K,P/K andK,showed significantly positive or negative correlations withelevation. Soil organic Cand total N in the higher elevations were significantly higher than those in thelower elevations,which were affected by both elevation and vegetation type. To some extent,both C/Pand N/P were affected by soil organic C and totalN while C/K,N/K and P/K were more affected by totalK.The average value of all stoichiometric ratios indicated that vegetation type hada stronger impact onsoil C/N/P, resulting in larger spatial variations.【Conclusion】The result showed that soil organic C and totalN are relative rice in the upper soil. Therefore,protecting the shrub meadow in high-frigid ecosystems isvery crucial for the vegetation restoration and rebuilt of Zheduo Mountain.