【摘要】 土壤阳离子交换量及交换性盐基离子在维持土壤养分和缓冲土壤酸化中起着非常重要的作用。研究不同地形高寒草地的土壤阳离子交换量及交换性盐离子的分布规律,有助于深入认识高寒草地土壤特性及其离子运动过程。以长江源区高寒草地为研究对象,研究了阴坡、滩地和阳坡3个不同地形土壤阳离子交换量及交换性钾钙钠镁离子的分布规律,并初步探讨其相关关系。结果表明,长江源区高寒草地不同坡向、不同土层的土壤全盐量TDS（%）为0.08%-0.20%,阳离子交换量CEC为19.68-74.33 cmol·kg^-1,且阴坡高寒草地的土壤阳离子交换量显著高于阳坡和滩地的阳离子交换量。土壤盐基离子含量基本呈现Ca²⁺>Mg²⁺>K⁺>Na⁺,符合一般规律。土壤交换性盐基总量在0-10 cm和10-20 cm土层呈现阴坡大于滩地和阳坡的规律,在20-40cm土层规律不明显。相关分析表明,土壤pH与交换性Ca²⁺和盐基饱和度呈显著正相关关系（P=0.002;P=0.034）。逐步回归分析表明,土壤含水量、pH、SOC和NH₄⁺-N 4个因子进入CEC的模型,NO₃^--N、pH和TN 3个因子进入Ca²⁺的模型,AK、AP、土壤含水量3个因子进入K+的模型,只有土壤NO₃^--N进入Na+的模型,但这些土壤因子都未能进入模型解释Mg²⁺的变化。综上,长江源区高寒草地土壤阳离子交换量和交换性盐基离子总量在不同坡向有明显差异,且均呈现阴坡大于滩地和阳坡的规律。更多还原

【Abstract】 Soil cation exchange capacity and the exchangeable base cations play important role in keeping soil nutrient and buffering soil acidification. Researching the distribution of soil cation exchange capacity and exchangeable base cations in alpine grasslands with different topography is of great significance for us to deeply understand soil characteristics and ion movement in alpine grassland ecosystems. In the present study, we took the alpine meadow as the research object to study the effect of slope aspect on soil cation exchange capacity（CEC） and exchangeable based cations in the source region of Yangtze River. Furthermore, we preliminarily explored the relationship among of the soil pH, exchangeable based cations Ca²⁺, Mg²⁺, Na⁺, K⁺ and Ca²⁺/Mg²⁺. The results showed that soil total salinities（%） were about 0.08%-0.20% across the different slope aspects in the alpine grassland. Soil CEC were 19.68-74.33 cmol·kg^-1, and the soil CEC at the north-facing slope grassland was significantly higher than those in the south-facing slope and the beach land grasslands. Soil exchangeable based cations appeared the Ca²⁺>Mg²⁺>K+>Na+, which in accordance with the universal pattern. The total amount of soil exchangeable based cations in north-facing slope grassland was significantly higher than those in the south-facing slope and the beach land grasslands, especially in the case of that at 0-10 cm and 10-20 cm. However, at the 20-40 cm, there was no obvious pattern among the three slope aspects grasslands for the total amount of soil exchangeable based cations. Pearson correlation analyses showed that soil pH was positively correlated with the exchangeable Ca²⁺ and the based saturation（P=0.002; P=0.034）. Stepwise regression analysis results showed that soil moisture, pH, soil organic carbon, and NH₄⁺-N were the main factors effecting the soil cation exchange capacity. NO₃^--N, pH and TN were the main factors effecting the exchangeable Ca²⁺. AK, AP, soil moisture were the main factors effecting the exchangeable K+. NO₃^--N was the main factor effecting the exchangeable Na+. However, these soil properties neither had a significant impact on the exchangeable Mg²⁺. In conclusion, soil cation exchange capacity（CEC） and the total exchangeable based cations in the alpine grasslands were different in the three slope aspects, north-facing slope, beach land, and the south-facing slope, in the source area of the Yangtze River. Summing up, CEC and the total exchangeable based ions shows a consistent pattern among the three slopes, that is north-facing slope>beach land>south-facing slope.更多还原