宁夏荒漠草原地上净初级生产力对降水的响应及其影响因子分析

Response of above-ground net primary productivity to precipitation change and influence factors in desert steppe of Ningxia

摘要:

【目的】 地上净初级生产力（ANPP）是植被群落特征重要表征指标，降水变化是影响干旱区荒漠草原植被群落特征的关键因素。在气候变化背景下，研究降水变化对荒漠草原地上净初级生产力的影响，对荒漠草原适应性管理具有重要的现实意义。【方法】 在毛乌素沙地南缘荒漠草原，利用遮雨棚和人工补水措施模拟了5种降水梯度，分别为自然降水的33%、66%、100%、133%、166%（记为 R33、R66、CK、R133和 R166），研究了荒漠草原地上净初级生产力（ANPP）对5种降水梯度的响应。 【结果】 降水变化影响物种数量和多样性指数，增加降水或减少降水均能减少物种数量。ANPP受降水量变化影响，不同优势种的ANPP对降水变化响应均不同，增加降水使猪毛蒿（Artemisia scoparia） ANPP增高，蒙古冰草（Agropyron mongolicum）ANPP降低。土壤有机碳（SOC）、土壤总氮（STN）、土壤总磷（STP）含量在R33处理下低于CK处理，SOC和STN在R166处理下高于CK处理。适当增加或减少降水均能降低土壤含水量（SWC），其中R133与其他处理有显著差异（P＜0.05）。SWC、pH值、 SOC、STN、STP与ANPP之间均呈正相关关系，而STP与地下生物量（BGB）呈负相关性。【结论】 荒漠草原ANPP对降水量呈现正反馈趋势，同时降水量通过影响群落多样性和土壤理化性质间接影响 ANPP，研究结果对荒漠草原生态系统功能评估和适应性管理提供了有力支撑。

Abstract:

【Objective】 Precipitation change is a key factor affecting the characteristics of desert grassland vegeta tion communities in arid zones，and above-ground net primary productivity （ANPP） is an important characterization index of vegetation communities，the study of precipitation change effects on above-ground net primary productivity of desert grasslands has important practical significance for the adaptive management of desert grasslands under the background of climate change.【Method】 In this study，we took the desert grassland at the southern edge of the Mu Us Sandy Land as the research object，and simulated five different precipitation gradients by using artificial rain shel ters and artificial recharge precipitation，which were 33%，66%，100%，133%，and 166% of the natural precipitation （R33，R66，CK，R133，and R166），and systematic studied about the response of aboveground net primary productiv ity to precipitation changes in desert steppes.【Result】 The results showed that changes in precipitation affected spe cies number and diversity index，increasing or decreasing precipitation could decrease species number. ANPP has af fected by precipitation changes. ANPP of different dominant species respond differently to precipitation changes. In creasing precipitation increases the ANPP content of Artemisia scoparia and decreases the ANPP content of Agropy ron mongolicum. The contents of soil organic carbon （SOC），soil total nitrogen （STN），and soil total phosphorus （STP） under R33 treatment were lower than CK treatment，while SOC and STN under R166 treatment were higher than CK treatment. Appropriate increase or decrease precipitation can reduce soil water content （SWC），among which R133 was significantly different from other treatments （P＜0. 05）. There is a positive correlation between SWC，pH，SOC，STN，STP and ANPP，while has negative correlation between STP and below-ground biomass （BGB）.【Conclusion】 Desert grassland ANPP shows a positive feedback trend to precipitation，and precipitation indi rectly affects ANPP by affecting community diversity，soil physical and chemical properties. The research results pro vide strong support for desert grassland ecosystem function assessment and adaptive management.