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生态学杂志 ›› 2020, Vol. 39 ›› Issue (11): 3633-3642.doi: 10.13292/j.1000-4890.202011.011

• 研究报告 • 上一篇    下一篇

大气水分亏缺对中国两种典型草地生态系统总初级生产力的影响

孟莹*,姜鹏,方缘   

  1. (中国气象局气象干部培训学院辽宁分院, 沈阳 110166)
  • 出版日期:2020-11-11 发布日期:2021-05-10

Contrasting impacts of vapor pressure deficit on gross primary productivity in two typical grassland ecosystems in China.

MENG Ying*, JIANG Peng, FANG Yuan   

  1. (Liaoning Branch of China Meteorological Administration Training Center, Shenyang 110166, China).
  • Online:2020-11-11 Published:2021-05-10

摘要: 土壤水分供给(SWC)和大气水分亏缺(VPD)是影响植物光合作用的重要变量。在生态系统初级生产力(GPP)方面,与SWC相比,关于VPD如何调控GPP变异的研究相对缺乏。本研究选取了水分限制的内蒙古温带草原(内蒙古站)和温度限制的青藏高原高寒灌丛草甸(海北站)作为研究对象,分析了VPD如何调控这两个生态系统GPP变异。按照研究时间段SWC与多年同时间段SWC均值的比值(RSWC)由小到大将两个站点的长时间序列数据划分为3个SWC水平:干旱25%(RSWC前25%区间)、中间50%(RSWC中间50%区间)和湿润25%区间(RSWC后25%区间)。结果发现,海北站不同SWC水平下VPD和GPP均表现出显著的正相关关系(P<0.05),相同SWC水平下VPD和GPP之间的关系无显著性差异(P>0.05)。与之不同,在低SWC中,内蒙古站的VPD和GPP表现出显著的负相关,但随着SWC的提高,这种负相关转化为正相关,二者关系在不同SWC水平间差异显著(P<0.05)。在仅考虑VPD和SWC对GPP影响的情境下,水分亏缺时内蒙古站的SWC可以解释超过60%的GPP变异,而海北站GPP变异的90%是由VPD所解释。本研究表明,在未来大气干旱日益增强的背景下,相对于低温、潮湿的生态系统,水分受限制的草地生态系统生产力可能更容易受到大气干旱的负向效应影响,并且该效应更加依赖土壤水分的变异。这为植被生产力模型如何将大气干旱效应耦合到模型中提供了重要的机理支持和参考,同时也有助于预测未来不同类型生态系统植被生产力对大气干旱的响应与适应。

关键词: 大气水分亏缺, 总初级生产力, 温带草原, 高寒灌丛草甸, 异质性响应

Abstract: Both soil water content (SWC) and vapor pressure deficit (VPD) play an important role in regulating plant photosynthesis. Relative to the SWC, the impacts of VPD on gross primary productivity (GPP) are still largely unknown. In this study, we chose a water-limited temperate steppe in Inner Mongolia (NM station) and a humid but temperaturelimited alpine shrub-meadow in Tibet (HB station) to examine the responses of GPP to VPD. According to the ratio of SWC in a specific study period to multiyear average SWC value (RSWC), data in both sites were classified into three groups: driest 25% (the top 25%), middle 50% (the middle 50%), and wettest 25% (the bottom 25%). Our results showed that there were positive relationships between VPD and GPP under three SWC levels in HB station (P<0.05), without differences under the same SWC level (P>0.05). By contrast, GPP declined with increasing VPD under the driest and middle SWC levels in NM station, whereas such negative correlation was translated into a positive one under the wettest SWC level (P<0.05). Significant differences were found in the slopes of the relationships between GPP and VPD under different SWC levels in the NM station. When only considering the effects of VPD and SWC on GPP, SWC accounted for more than 60% of the variations in GPP under low SWC level in NM station, whereas VPD accounted for 90% of the variations of GPP in HB station. Our results revealed that the waterlimited grassland may be more vulnerable to high VPD in the future relative to the humid but temperature-limited ecosystems. Our results provide an important mechanism support and reference for how the vegetation productivity model couples the atmospheric drought effect into the model and also helpful for predicting the responses and adaptations of vegetation productivity to atmospheric drought in different ecosystems.

Key words: vapor pressure deficit, gross primary productivity, temperate steppe, alpine shrub-meadow, contrasting response.