长白山苔原带土壤温度与肥力随海拔的变化特征

土壤温度与土壤肥力的分解释放、植被生长密切相关。利用2015年8月至2017年6月长白山西坡苔原带5 cm土壤温度并测试其土壤肥力，分析了土壤温度与肥力随海拔的变化特征及土壤温度对苔原带肥力的影响。结果表明：（1）长白山西坡苔原带土壤最热月为8月，最冷月为1、2月。长白山西坡苔原带土壤年均温随海拔的升高而下降，垂直变化率为-0.44℃·（100m）^-1。月均温垂直变化率则有所差别，5-9月垂直变化率为正，其余月份垂直变化率为负。（2）海拔是土壤温度空间分异的主要影响因素，冷季土壤温度随海拔升高而显著降低。随着海拔升高，越稀疏的植被和越薄的土层使得土壤热容量越小，暖季土壤温度随海拔升高而显著升高。（3）长白山西坡苔原带土壤肥力，尤其是与植物生长关系密切的速效养分随海拔升高表现出先升高再降低，在植物多样性和丰富度及草本植物盖度最高的2 250 m处达到土壤肥力最高水平。低海拔（2 050~2 250 m）的土壤肥力水平明显高于高海拔（2 350~2 550 m）的土壤肥力水平。西坡苔原带土壤肥力的空间分异状况受草本植物入侵影响较大。（4）长白山西坡苔原带土壤肥力水平随土壤温度升高而升高，温度是土壤有机质分解和矿物质养分转化的限制性因素。建议山地苔原带生态系统生产和生态管理中要重点考虑草本植被入侵给土壤肥力带来的影响。

Altitude-dependent soil temperature and fertility in the alpine tundra of the Changbai Mountains

Soil fertility releasing and vegetation growth are dependent to soil temperature. Statistical analysis has been used to analyze the altitude-dependent change in soil temperature and soil fertility, and to discuss the effect of soil temperature on soil fertility in the alpine tundra on the western slope of the Changbai Mountains. The results showed that:(1) August is the warmest month, January or February is the coldest month in the alpine tundra. Annual mean soil temperature decreases with altitude, with a vertical lapse rate of -0.44℃·(100m)^-1. However, the vertical lapse rate of soil temperature is different from month to month. The vertical lapse rate of mean soil temperature is positive during May to September, but is negative during the other months. (2) Altitude is the main factor controlling the spatial change in soil temperature. In cold season, soil temperature remarkably decreases with rising altitude, whereas the soil temperature increases slowly with rising altitude in warm season, because of soil heat capacity becoming lower due to less vegetation and thinner soil layer along altitude increasing. (3) The soil fertility first increases then decreases with altitude. At 2 250 m, plant species richness and diversity and the relative coverage of herbaceous plant reach the highest level, where the soil fertility reach, therefore, the richest level. The effect of herbaceous plant invasion on soil fertility is important and significant. (4) The soil fertility increases with the increase of soil temperature. Temperature is the restrictive factor of soil fertility releasing and converting in the alpine tundra on the western slope of the Changbai Mountains. The effect of herbaceous plant invasion on soil fertility should be taken into account seriously for ecological management and control.