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研究了贺兰山不同海拔梯度土壤活性有机碳(SAOC)的垂直分布特征及其与气候因子、植被特征和土壤特性的关系。结果表明:SAOC随海拔增加而增加,垂直方向随土层深度的增加呈“T”形分布特征,各海拔间差异均显著(P<0.05)。相关性分析表明:不同海拔梯度SAOC与土壤有机碳(SOC)、含水量、全氮、植被盖度和多样性指数呈极显著线性正相关(P<0.01),与pH、土壤温度和土壤容重呈极显著线性负相关(P<0.01),与年降雨量、年均气温、地上和地下生物量无线性相关性(P>0.05);SAOC占总有机碳的比例变化范围在7.9%~12.0%之间,以高寒草甸(AM)所占比例最高,草原化荒漠(DS)最低。偏相关分析显示,影响0-20cm土层SAOC最主要的因子是有机碳、多样性指数、植被盖度和年降水量,影响20-40cm土层SAOC的最主要因子是年降雨量和地下生物量,影响40-60cm土层SAOC最主要的因子是植被盖度和地下生物量,影响60-80cm土层SAOC最主要的因子是pH、含水量和地下生物量。综合分析比较可知,有机碳、多样性指数、植被盖度、年降水量、地下生物量、pH和含水量可能是影响SAOC垂直分异的关键因子,而土壤有机碳、全氮、含水量、植被盖度、pH、土壤容重和温度可能是影响SAOC沿海拔梯度分异的关键因子。
The vertical distribution of soil active organic carbon (SAOC) and its relationship with climatic factors, vegetation characteristics and soil characteristics at different altitudes in Helan Mountain were studied. The results show that the SAOC increases with the elevation, and the vertical distribution increases with the depth of the soil, showing a “T” shape distribution with significant differences (P <0.05). Correlation analysis showed that there was a significant linear positive correlation between SAOC and soil organic carbon (SOC), water content, total nitrogen, vegetation coverage and diversity index (P <0.01), and different soil pH, soil temperature and soil bulk density (P <0.01), and had no linear correlation with annual rainfall, annual mean temperature, above-ground biomass and aboveground biomass (P> 0.05). The proportion of SAOC in total organic carbon ranged from 7.9% to 12.0 %, The highest proportion is alpine meadow (AM), and the lowest is prairie desert (DS). Partial correlation analysis showed that the main factors affecting SAOC in 0-20cm soil layer were organic carbon, diversity index, vegetation coverage and annual precipitation. The main factors affecting SAOC in 20-40cm soil layer were annual rainfall and subsurface biomass The main factors influencing the SAOC of 40-60cm soil layer are the vegetation coverage and the underground biomass. The main factors influencing the SAOC of 60-80cm soil layer are pH, water content and underground biomass. Comprehensive analysis shows that organic carbon, diversity index, vegetation coverage, annual precipitation, underground biomass, pH and water content may be the key factors affecting the vertical differentiation of SAOC. However, soil organic carbon, total nitrogen, water content, Vegetation coverage, pH, soil bulk density and temperature may be the key factors affecting the variation of SAOC along altitudinal gradient.