中国中高纬地区植被物候对干旱的响应特征研究

Characterization of Vegetation Phenology in Response to Drought in the Middle and High Latitudes of China

  • 摘要: 植被物候直接影响其生物量,调控生态系统碳循环过程。目前,气候变化(尤其干旱)对中国中高纬度植被物候的影响依然不清楚。因此,文章基于GIMMS NDVI3g数据集,提取中国30° N以北地区中多种植被类型生长季的开始日期(Start of the Season,SOS)与结束日期(End of the Season,EOS)两物候参数。然后结合野外观测数据,验证提取物候参数结果可靠性,并结合饱和水汽压差(Vapor Pressure Deficit, VPD)与改进后的标准化降水蒸散指数(Standardized Precipitation Evapotranspiration Index, SPEI)探究植被物候对干旱的响应特征规律。结果表明:(1)不同地区的植被物候变化呈现明显的差异性,单季植被与双季植被第1个生长季的SOS集中在每年的第30~180天,而双季植被第2个生长季的SOS集中在每年的第200~220天。单季植被与双季植被第1个生长季的EOS主要集中在每年的第180~300天,双季植被第2个生长季的EOS主要集中在每年的第260~300天。(2)森林季前VPD的上升导致植被的SOS提前及EOS延迟;草地季前VPD上升导致植被的SOS滞后以及EOS提前。(3)研究区内大部分地区的SPEI与植被的SOS、EOS均呈正相关,即干旱促使该地区植被的SOS、EOS提前。

     

    Abstract: Vegetation phenology directly affects its biomass and regulates ecosystem carbon cycling processes. Currently, the impacts of climate change (especially drought) on vegetation phenology at mid- to high-latitudes in China are still unclear. Therefore, based on the GIMMS NDVI3g data, the Start of the Season (SOS) and End of the Season (EOS) parameters for the growing seasons of several vegetation types in the region north of 30° N were extracted. The extracted data were then combined with field observations to verify the effects of climate change on ecosystem carbon cycling. The results were then combined with field observations to verify the reliability of the parameters, and the saturated vapor pressure difference (VPD) and the improved standardized precipitation evapotranspiration index (SPEI) were used to investigate the characteristic patterns of vegetation phenology in response to drought. The results showed that: (1) the vegetation phenology varied significantly in different regions, with the SOS of the first growing season of mono- and bi-coastal vegetation concentrated between the 30th and 180th days of the year, and the SOS of the second growing season of bi-coastal vegetation concentrated between the 200th and 220th days of the year. The EOS spanning the 1st growing season of single-season and double-season vegetation was mainly concentrated between the 180th and 300th day of the year, and the EOS of the 2nd growing season of double-season crops was mainly concentrated between the 260th and 300th day of the year. (2) The rise of forest pre-season VPD leads to advancement of SOS and delay of EOS of vegetation; the rise of grass pre-season VPD leads to lagging of SOS and advancement of EOS of vegetation. (3) SPEI was positively correlated with SOS and EOS of vegetation in most parts of the study area, drought tended to contribute to the advancement of SOS and EOS of vegetation in the area.

     

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