With the intensification of climate change, the frequency, duration and scope of drought have become more and more serious. Exploring the responses of plant photosynthesis to drought and the impacts of meteorological factors on photosynthesis is of great significance to the dealing with drought stress. Solar-induced chlorophyll fluorescence (SIF) based on remote sensing has the potential for early monitoring and accurate assessment of regional vege-tation photosynthesis under drought conditions. Based on the spaceborne SIF information and the standardized precipitation evapotranspiration index (SPEI), we investigated the responses of vegetation photosynthesis to drought and the influence of meteorological factors in the growing season (April to October) of the Loess Plateau during 2001-2017. The results showed that about 87.8% of total areas of the Loess Plateau had a significant positive correlation between SIF and SPEI. Vegetation photosynthesis in semi-arid area was more sensitive to drought and less sensitive in semi-humid area. Different vegetation types had different photosynthetic responses to drought. Grassland had the highest sensitivity to drought with three to four months SPEI time-scale, while forest had the lowest sensiti-vity with three to ten months SPEI time-scale. There was a significant correlation between meteorological factors and SIF. Temperature and precipitation were the most important factors affecting vegetation photosynthesis on the Loess Plateau. Photosynthetically active radiation showed a similar controlling strength to temperature. The impacts of drought and meteorological factors on vegetation photosynthesis were largely determined by differences in drought resistance among ecosystem types and climate regions.
随着气候变化的加剧,干旱的频率、持续时间以及发生范围都越来越严重,探索植被光合对干旱的响应以及气象因子对植被光合的影响对于人们如何应对干旱具有重要意义。基于遥感的日光诱导叶绿素荧光(SIF)具有对干旱条件下区域植被光合作用进行早期监测和准确评估的潜力。本研究基于星载SIF和标准化降水蒸散发指数(SPEI)研究了黄土高原地区2001—2017年生长季内(4—10月)植被光合作用对干旱的响应关系及其受气象因子的影响程度。结果表明: 黄土高原地区植被生长季内SIF与SPEI呈显著正相关关系的区域占比为87.8%,其中,半干旱地区植被光合对干旱的响应较敏感,半湿润地区敏感性较低。不同类型植被光合对干旱的响应存在差异,草地对干旱响应的敏感性最高,响应最强的SPEI时间尺度为3～4个月;林地的敏感性最低,SPEI时间尺度为3～10个月。气象因子与SIF存在显著的相关关系,其中,温度和降雨是影响黄土高原植被光合的重要影响因子,光合有效辐射的影响模式与温度相似。黄土高原地区生长季内不同的气候和植被类型条件下,植被光合所受干旱及各气象因素的影响存在较大差异。.
Keywords: Loess Plateau; meteorological drought; solar-induced chlorophyll fluorescence; standardized precipitation evapotranspiration index; vegetation photosynthesis.