单 位：
中国科学院水利部水土保持研究所;中国科学院大学;西北农林科技大学草业与草原学院;西北农林科技大学黄土高原土壤侵蚀与旱地农业国家重点实验室
关键词：
退耕还草;植物养分;生态化学计量比;土壤含水率;黄土高原
摘 要：
揭示土壤水分含量变化对植物养分吸收的影响,对阐明草本植被对环境变化的响应和适应性具有重要意义,可为黄土高原区生态治理提供理论依据。研究以安塞纸坊沟流域不同退耕还草年限(6 a, 15 a, 25 a和45 a)的草本植物和0—50 cm深度土壤样品为研究对象,测定了植物地上部C,N,P,K,Ca和Mg含量及土壤含水率,并分析了植物养分含量及其生态化学计量与土壤含水率的关系。结果表明:土壤含水率随退耕还草过程呈先增加后降低趋势。植物体中C,N,K,Ca和Mg含量整体上随着退耕年限延长先降低后升高,植物P含量在退耕还草初期下降,中后期保持稳定。植物C/N,C/P和N/P比值随退耕年限呈先升高后降低的趋势,并且在退耕还草过程中植物生长主要受到N限制。植物Ca和Mg含量与土壤含水率呈显著负相关。另外,退耕45 a含水率最低,植物C/Ca, C/Mg, N/Ca, N/Mg, P/K,P/Ca, P/Mg比值也是最低的,表明植物可以增加吸收K,Ca和Mg以应对水分胁迫。研究表明土壤含水率随退耕还草过程降低,土壤水分降低促进干旱半干旱地区植被对环境的适应。研究结果为改善干旱半干旱区植被生态稳定性提供科学依据。
译 名：
Effects of Soil Moisture on the Stoichiometric Characteristics of Aboveground Plants Following Conversion of Farmland to Grassland on the Loess Plateau
作 者：
JIN Xiaolian;ZHAO Wei;LI Mengdi;LIU Dongdong;JU Wenliang;College of Grassland Agriculture, Northwest A&F University;State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University;Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources;University of Chinese Academy of Sciences;
关键词：
returning farmland to grassland;;plant nutrient;;ecological stoichiometry;;soil moisture;;Loess Plateau
摘 要：
It is important to reveal the influence of soil moisture content changes on plant nutrient uptake and to explain the response and adaptation of herbaceous vegetation to environmental changes, which can provid a theoretical basis for ecological management in the Loess Plateau. Herbs and soil samples in the depth of 0—50 cm in different grassland restoration ages(6 years, 15 years, 25 years, and 45 years) in Zhifanggou watershed in the hilly and gully region of the Loess Plateau were collected. The contents of C, N, P, K, Ca, and Mg in plants and the soil moisture contents were measured, and the correlation between plant nutrients and their ecological stoichiometry and soil moisture content was analyzed. The results showed that the soil moisture content increased firstly and then decreased following the conversion of farmland to grassland; the contents of C, N, K, Ca, and Mg in plants as a whole decreased firstly and then increased following the conversion of farmland to grassland; the P contents of plants decreased in the early stage of returning farmland to grassland and remained stable in the middle and late stages; the ecological stoichiometric ratios of plant C/N, C/P and N/P showed a trend of first increasing and then decreasing following the conversion of farmland to grassland, and the plants in the restored grassland were limited by N; Ca and Mg contents of plants were significantly negatively correlated with the soil moisture contents; additionally, farmland converted 45 years ago had the lowest soil moisture content, and the lowest ratios of C/Ca, C/Mg, N/Ca, N/Mg, P/K, P/Ca, P/Mg in plants. These results suggest that water stress induces plants to absorb K, Ca and Mg from soils to resist drought. This study found that soil water content decreases with the process of returning farmland to grassland, and the decrease of soil water promotes the adaptation of vegetation to the environment in arid and semi-areas. These research results can provide a scientific basis for improving the ecological stability of vegetation in arid and semi-arid areas.
