中国保护区总初级生产力对极端干热复合事件的响应

Response of vegetation gross primary productivity to extreme compound drought heatwave events in protected areas of China

  • 摘要: 以标准化干热指数(standardized dry and hot index,SDHI)作为干热复合指标,评估2001—2019年中国暖季植被总初级生产力(gross primary production,GPP)和SDHI的时空变化特征,分析GPP对SDHI和极端干热复合事件的响应关系和响应时间尺度以及保护区内外乔木林地和灌木草地GPP对SDHI和极端干热复合事件的响应关系差异.结果表明:1)中国暖季GPP变化趋势呈南北上升,中间下降的特征,且大部分地区呈上升趋势;2)中国暖季SDHI变化趋势呈北升南降的特征,且大部分地区呈下降趋势,干热化程度加重;3)中国暖季GPP对干热变化的平均响应时间为1.50个月,响应时间的空间异质性不明显,保护区内的乔木林地和灌木草地的植被生长更不容易受到干热复合的限制;4)中国暖季GPP对极端干热复合事件的平均响应时间为0.88个月,响应时间在空间分布上呈现北低南高的特征,保护区对于帮助植被尤其是灌木草地抵御极端干热复合事件的作用不明显.研究结果有助于揭示GPP对极端干热复合事件的响应关系,为气候风险评估和制定气候变化应对方案提供了科学依据.

     

    Abstract: With the increasing global warming and the frequent occurrence of extreme compound drought heatwave events, it is still unclear how the gross vegetation primary productivity (GPP) in the protected areas of China has been affected. In this paper, we used the Standardized Dry and Hot Index (SDHI) as an indicator of compound drought and hotness to assess the spatial and temporal characteristics of GPP and SDHI in China's warm seasons from 2001 to 2019. We then analyzed the relationship and time scales between the response of GPP to SDHI and extreme compound drought heatwave events. Additionally, we explored the differences in the response relationship between GPP of forest lands and shrub grasslands inside and outside the protected areas to SDHI and extreme compound drought heatwave events. The results show that (1) the trend of warm season GPP change in China is characterized by rising in the north and south and decreasing in the middle, and most of the regions show an upward trend. (2) The trend of warm season SDHI change in China is characterized by rising in the north and decreasing in the south, and most of the regions show a downward trend, indicating an intensification of drying and heating. (3) The average response time of warm season GPP to drought and hotness changes in China was 1.50 months, and the spatial heterogeneity of response time was not obvious, and the vegetation growth of forest lands and shrub grasslands within the protected area was less susceptible to the limitations of compound drought and hotness. (4) The average response time of warm season GPP to extreme compound drought heatwave events in China was 0.88 months, and the spatial distribution of response time was characterized by low in the north and high in the south. The role of protected areas in helping vegetation, especially shrub grasslands, to withstand extreme compound drought heatwave events was not obvious. The results of the study help to reveal the response relationship of GPP to extreme compound drought heatwave events, and provide a scientific basis for climate risk assessment and the formulation of climate change response programs.

     

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