中文关键词荒漠草原降雨变化植物群落多样性土壤C:N:P干湿年份 英文关键词desert grasslandchange of precipitationplant community diversitysoil C:N:Pwet and dry years

作者	单位	E-mail
高江平	西北师范大学地理与环境科学学院, 兰州 730070	gaojiangpingwl@126.com
赵锐锋	西北师范大学地理与环境科学学院, 兰州 730070	zhaoruifeng@126.com
张丽华	西北师范大学地理与环境科学学院, 兰州 730070
王军锋	西北师范大学地理与环境科学学院, 兰州 730070
谢忠奎	中国科学院西北生态环境资源研究院皋兰生态与农业综合试验站, 兰州 730000

中文摘要 研究降雨格局变化对植物群落多样性、土壤C：N：P生态化学计量特征的影响，以及关键土壤因子与植物群落多样性间的关系，对于荒漠草原植物群落多样性的保护具有重要意义.本文以黄土高原西部荒漠草原为研究对象，通过3 a野外降雨控制试验（减少40%降雨、减少20%降雨、自然降雨、增加20%降雨和增加40%降雨），探讨干湿年份下降雨变化对植物群落多样性及其土壤C：N：P生态化学计量特征的影响，以及降雨变化下土壤C：N：P生态化学计量特征及关键土壤因子与植物群落多样性的关系.结果表明，在正常年份与偏干年份（2013年与2015年），Patrick丰富度和Shannon-Wiener多样性指数分别以减雨20%处理显著低于对照和增雨40%处理，在偏湿年份（2014年），Patrick丰富度和Shannon-Wiener多样性指数对降雨处理无显著差异.在正常年份与偏干年份，随降雨量的增加土壤有机碳（SOC）、全氮（TN）、全磷（TP）、碳氮比（C：N）、碳磷比（C：P）和氮磷比（N：P）呈降低趋势，其中，C：N显著降低；在偏湿年份，随降雨量增加土壤SOC、TN、C：P和N：P呈上升趋势.在正常年份，降雨处理对土壤含水量影响不显著，导致土壤含水量对植物群落影响有限，SOC、TN、N：P、C：N和微生物量氮（MBN）对植物群落多样性的影响更为突出；在偏湿年份，年降雨量丰富，降雨量增加导致土壤养分上升，水分不是限制植物生长的最重要因素，土壤含水量、土壤养分与生态化学计量特征共同调节和控制着植物群落多样性；在偏干年份，降雨处理对土壤含水影响显著，且降雨量增加导致土壤养分流失较多，因此，土壤含水量成为影响植物群落多样性的最主要因素.由此可知，在不同干湿年份，植物群落多样性与土壤C：N：P生态化学计量特征对降雨变化的响应不同；土壤C：N：P对植物群落多样性的影响也不同，本文的研究结果旨在为未来降雨变化下荒漠草原的保护与管理提供一定的理论依据. 英文摘要 Studying the influence of precipitation patterns on plant community diversity, soil C:N:P ecological stoichiometric characteristics, and the relationships between key soil factors and plant community diversity is of great significance for the protection of plant community diversity in desert grasslands. This paper was studied in the desert steppe of the west of Loess Plateau using a three-year precipitation manipulation experiment (40% reduction in precipitation, 20% reduction in precipitation, natural precipitation, 20% increase in precipitation, and 40% increase in precipitation), explored the influence of changes in precipitation in dry and wet years on the diversity of plant community and soil C:N:P ecological stoichiometric characteristics. And we also explored the relationship between soil C:N:P ecological stoichiometric characteristics and the key soil factors and the diversity of plant community under changes in precipitation. The results showed that in a normal year and the drier year (2013 and 2015), Patrick richness and Shannon-Wiener diversity index were significantly low under the 20% reduction treatment compared with the control and 40% increase treatments, respectively. During the wetter year, Patrick richness and Shannon-Wiener diversity index were no different between any of the precipitation treatments. In the normal year and the drier year, the soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents and the carbon-nitrogen ratio (C:N), carbon-phosphorus ratio (C:P), and nitrogen-phosphorus ratio (N:P) all decreased with an increase in precipitation (the decrease in the C:N ratio was statistically significant). During the wetter year, SOC, TN, C:P, and N:P increased with an increase in precipitation. During the normal year, precipitation treatments had no significant influence on soil water content, having a limited influence on the plant community. TN, N:P, SOC, C:N, and microbial biomass nitrogen (MBN) had a more prominent influence on plant community diversity. In the wetter year, precipitation was abundant leading to a rise in soil nutrients. Water was not the most important factor limiting to plant growth whereas soil water content, soil nutrients, and ecological stoichiometric characteristics jointly regulate plant community diversity. In the drier years, precipitation treatments had a significant impact on soil water content, whereby an increase in precipitation led to high losses of soil nutrients. Therefore, soil water content was the most important factor affecting plant community diversity during drier years. These observations indicate that under dry and wet years, plant community diversity and soil C:N:P ecological stoichiometric characteristics have variable responses to precipitation and soil C:N:P effect on plant community were also different. These results provide a theoretical basis for the protection and management of desert steppe systems under future projected changes in precipitation.

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