School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China.
School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; Jixian National Forest Ecosystem Observation and Research Station, CNERN, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China.
Sci Total Environ. 2023 Nov 15;899:165718. doi: 10.1016/j.scitotenv.2023.165718. Epub 2023 Jul 22.
Climate change has increased the frequency and length of droughts, but many uncertainties remain regarding the impacts of this aridification on terrestrial ecosystem function. Vegetation water use efficiency and carbon sequestration capacity are crucial determinants that both respond to and mediate the effects of drought. However, it is important to note that the consequences of drought on these processes can persist for years. A deeper exploration of these "drought legacy effects" will help improve our understanding of how climate change alter ecosystem carbon-water cycling. Here, we investigate the spatial patterns of drought legacy effects on remotely-sensed vegetation greenness (NDVI), net primary productivity (NPP) and water use efficiency (WUE) in southwestern China, a biodiversity hotspot that was impacted by an extreme drought in 2009-2010, with a particular focus on the tradeoff between WUE and NPP. Despite widespread negative drought legacy effects in NDVI (impacting 61.26 % of the study region), there was a general increase in NPP (58.68 %) and a decrease in WUE (67.53 %) in the year following drought (2011). This drought legacy effect was most evident in forests, while drought legacies in grasslands were less common. Drought legacies were also most apparent in relatively warm and humid areas. During the study period (2002 to 2018), we found that drought impacts on WUE also lagged behind changes in NPP by 1-2 years in forests, which highlights how drought legacies may manifest differently across ecosystem processes. Our study demonstrated that severe drought conditions may significantly affect the carbon sequestration capacity and water use efficiency of vegetation in southwestern China, and that forests may compensate for the detrimental effects of water stress by increasing water use and biomass growth after drought episodes.
气候变化增加了干旱的频率和持续时间，但干旱化对陆地生态系统功能的影响仍存在许多不确定性。植被水分利用效率和碳固存能力是关键的决定因素，它们既响应又调节干旱的影响。然而，需要注意的是，干旱对这些过程的影响可能会持续多年。深入研究这些“干旱遗留效应”将有助于我们了解气候变化如何改变生态系统的碳-水循环。在这里，我们调查了 2009-2010 年极端干旱事件后，中国西南部的遥感植被绿色度（NDVI）、净初级生产力（NPP）和水分利用效率（WUE）的干旱遗留效应的空间格局，该地区是生物多样性热点地区，特别关注 WUE 和 NPP 之间的权衡。尽管 NDVI 普遍存在负面的干旱遗留效应（影响研究区域的 61.26%），但在干旱后一年（2011 年），NPP 普遍增加（58.68%），WUE 下降（67.53%）。这种干旱遗留效应在森林中最为明显，而在草原中则不太常见。干旱遗留效应在相对温暖和潮湿的地区也最为明显。在研究期间（2002 年至 2018 年），我们发现森林中干旱对 WUE 的影响滞后于 NPP 的变化 1-2 年，这表明干旱遗留效应可能在不同的生态系统过程中表现不同。我们的研究表明，严重的干旱条件可能会显著影响中国西南部植被的碳固存能力和水分利用效率，并且森林可能通过在干旱事件后增加水分利用和生物量生长来补偿水分胁迫的不利影响。
