高寒山区不同土地利用类型土壤养分化学计量特征及影响因素

了解高寒地区不同土地利用类型下土壤养分化学计量特征及其影响因素可为评估脆弱生态系统土壤质量和功能提供参数。通过测定青海省东部24个样点0—30 cm土壤基本理化性质(pH、容重BD、孔隙度P_s、黏粒含量C_y、土壤含水量SWC、有机碳SOC、全氮TN、全磷TP、速效氮AN和速效磷AP),并提取各样点环境因子数据(年均温MAT、年均降雨量MAP、年均蒸发量E_a、植被归一化指数NDVI、海拔ALT、坡度SG、地表粗糙度SR、经度LON和纬度LAT),分析了农、林、草三种土地利用类型下土壤养分化学计量比分布特征及其影响因素。结果表明，农地土壤有机碳SOC和全氮TN含量显著低于林地和草地(P<0.05),而全磷TP和速效磷AP含量则相反，农、林、草地速效氮AN含量无显著差异(P>0.05)。农、林、草地不同深度土壤C∶N(平均值19.93,变异系数<16%)和AN∶AP(平均值2.73,变异系数<71%)较为稳定且无显著差异(P>0.05),而农地C∶P和N∶P(平均值分别为19.27和0.99)却显...

Stoichiometric characteristics and influencing factors of soil nutrients under different land use types in an alpine mountain region

Understanding the stoichiometric characteristics and influencing factors of soil nutrients under different land use types in the alpine regions can provide parameters for evaluating soil quality and function of the fragile ecosystems. In this study, the basic soil properties, including soil pH, bulk density (BD), porosity (P_s), clay content (C_y), soil water content (SWC), soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), available phosphorus (AP), were measured in the 0-30 cm soil layers from 24 sites in the eastern Qinghai Province. The environmental factor data which include mean annual temperature (MAT), mean annual precipitation (MAP), average annual evaporation (E_a), normalized differential vegetation index (NDVI), altitude (ALT), slope gradient (SG), surface roughness (SR), longitude (LON), latitude (LAT) were extracted at the same time using the ArcGIS software, in order to analyze the distribution characteristics and controls of soil nutrient stoichiometry under three land use types (farmland, forestland and grassland). The results showed that the content of SOC and TN in the farmland was significantly lower than that in the forestland and grassland, while the content of TP and AP showed an opposite trend compared with SOC and TN; there was no significant difference in AN content among the farmland, forestland and grassland. C:N (the average value is 19.93, the coefficient of variance is lower than 16%) and AN:AP (the average value is 2.73, the coefficient of variance is lower than 71%) in different soil layers of farmland, forestland and grassland remained relatively stable and exhibited no significant differences (P>0.05), while C:P and N:P of the farmland (the average value is 19.27 and 0.99, respectively) were significantly lower than those of forestland (the average value is 84.88 and 4.12, respectively) and grassland (the average value is 75.26 and 3.87, respectively), indicating that there was a lack of nitrogen in the soils of farmland. Redundancy analysis showed that different environmental factors and soil properties had different contributions to the soil nutrient stoichiometry ratio. The contributions of environment factors that had significant impacts on soil nutrient stoichiometric followed the order of MAT (38.3%), E_a (34.9%), ALT (32.6%), MAP (30.2%), LAT (24.2%) and NDVI (17.9%); the contributions of soil properties followed the order of TN (60.3%), SOC (59.2%), BD (56.4%), P_s (55.6%), C_y (39.3%), SWC (36.3%), AP (23.6%), pH (22.8%), TP (12.0%) and AN (9.9%). Increasing the fertilizer application of limiting elements and planting nitrogen-fixing plants could alleviate the phenomenon of nitrogen deficiency in alpine mountainous areas.