摘要
全球气候变化背景下极端降水事件频发将会影响半干旱草原土壤氮(N)的转化过程,但土壤N转化关键过程如何响应降水变化及其总氮矿化速率对不同降水水平的敏感性尚不清楚。该研究依托中国北方草原全球变化联网实验平台的草甸草原、典型草原和荒漠草原3种草原类型,采用15N库稀释法,测定了土壤总氮矿化速率(GNM)、土壤总硝化速率(GN),以及相关的生物(微生物生物量碳、氮含量,地下生物量(BGB))、非生物(土壤温度(ST)、土壤含水量(SWC))和土壤底物(土壤铵态氮(NH4+-N)、硝态氮(NO–3-N)、可溶性有机碳、氮含量)指标。结果表明:不同类型草原GNM存在显著差异,从高到低依次是草甸草原((3.284±0.613)mg·kg^(-1)·d^(-1))、典型草原((1.370±0.167)mg·kg^(-1)·d^(-1))和荒漠草原((0.724±0.216)mg·kg^(-1)·d^(-1))。增减50%的降水对3种草原土壤GNM和GN没有产生显著影响。典型草原和荒漠草原土壤GNM和GN对降水减少的敏感性显著高于对降水增加的敏感性,而草甸草原土壤GNM和GN的敏感性在增减降水间无显著差异。结构方程模型(SEM)分析揭示了土壤水分是影响土壤GNM的主要因子。以上结果表明短期的极端降水对中国北方3种重要草原土壤GNM和GN没有产生显著影响,但改变了其对降水变化的敏感性。未来极端降水事件增加如何影响陆地生态系统土壤N的转化过程尚需进行长时间尺度和大空间格局的系统研究。
Aims In the context of global climate change,frequent extreme precipitation events will affect the soil nitrogen transformation processes in the semi-arid steppe.However,it remains unclear how the key processes of soil nitrogen transformation respond to precipitation change and how the total nitrogen mineralization rate is sensitive to different precipitation levels.Methods This study was conducted on the meadow steppe,typical steppe,and desert steppe of the Global Change Network test platform of the northern China Steppe.In this study,the gross nitrogen mineralization rate(GNM)and gross nitrification rate(GN)of soil were measured by the 15N isotopic pool dilution method,as well as related biological(microbial biomass carbon content,microbial biomass nitrogen content,background biomass(BGB)),and abiotic(soil temperature(ST),soil water content(SWC)),soil substrate(soil ammonium nitrogen(NH4+-N)content,nitrate nitrogen(NO–3-N)content,soluble organic carbon content,soluble organic nitrogen content)indexes.Important findings The results showed significant differences in GNM among different steppe types.The highest GNM was in meadow steppe((3.284±0.613)mg·kg^(-1)·d^(-1)),followed by typical steppe((1.370±0.167)mg·kg^(-1)·d^(-1))and desert steppe((0.724±0.216)mg·kg^(-1)·d^(-1)).However,the 50%decrease in precipitation had no significant effects on the GNM and GN of the three grasslands.The sensitivity of GNM and GN to precipitation reduction in typical steppe and desert steppe soil was significantly higher than that of precipitation increase.In contrast,the sensitivity of GNM and GN in meadow steppe soil was not significantly different between precipitation increase and decrease.Structural equation model(SEM)analysis revealed that SWC was the main factor affecting the soil GNM.These results indicate that short-term extreme precipitation has no significant effects on the GNM and GN of three important grasslands in northern China,but changes their sensitivity to precipitation change.How the increase of extreme precipitation events will affect the soil nitrogen conversion process in terrestrial ecosystems in the future needs to be systematically studied over long time scales and large spatial patterns.
作者
韩菲
王袼
武帅楷
林茂
董宽虎
王常慧
苏原
HAN Fei;WANG Ge;WU Shuai-Kai;LIN Mao;DONG Kuan-Hu;WANG Chang-Hui;SU Yuan(College of Grassland Science,Shanxi Agricultural University,Taigu,Shanxi 030801,China;Shanxi Key Laboratory of Grassland Ecological Protection and Native Grass Germplasm Innovation,Taigu,Shanxi 030801,China;Youyu Loess Plateau Grassland Ecosystem National Research Station,Youyu,Shanxi 037200,China)
出处
《植物生态学报》
北大核心
2025年第5期697-709,共13页
Chinese Journal of Plant Ecology
基金
国家自然科学基金(U22A20576和32371670)
国家重点研发计划(2022YFF1302801)
山西省科技厅平台专项(202104010910017)
山西农业大学高层次引进人才专项(2021XG008)的资助。
关键词
北方草原
总氮矿化
极端降水
敏感性
土壤水分
northern grassland
gross nitrogen mineralization
extreme precipitation
sensitivity
soil moisture
