School of Ecology and Nature Conservation, Beijing Forest University, Beijing, China.
School of Ecology and Nature Conservation, Beijing Forest University, Beijing, China.
Sci Total Environ. 2022 Jan 1;802:149643. doi: 10.1016/j.scitotenv.2021.149643. Epub 2021 Aug 13.
Southwest China is an important biodiversity hotspot in the world and is controlled by the Pacific and Indian Ocean monsoon in the east and west part respectively. However, how abiotic and biotic factors affect the response of vegetation to climate change in different monsoon regions is still not clear. Here we used the annual change rate of growing-season normalized difference vegetation index (NDVI trend) during 1982-2015 to explore the vulnerability of vegetation (forests and shrubs) activity to climate change in southwest China. We examined NDVI trend in relation to: 1) climate change trends, i.e. annual change rate of water and energy availability, indicated by the Palmer Drought Index (PDSI) and potential evapotranspiration (PET), respectively; 2) climatic condition, i.e. mean PDSI and PET during 1982-2015; 3) vegetation height; 4) biome type; 5) monsoon region. The results showed that NDVI generally increased in the Pacific monsoon region, especially in the southern areas, probably because the vegetation under more productive climate were more resistant to climate change, and also because decreased temperature lead to lower evapotranspiration which alleviated the slight drought trend in this region. In contrast, NDVI generally decreased in the Indian Ocean monsoon region which showed more pronounced drought trend, especially in the tall subalpine and tropical forests of Southeast Tibetan Mountains, which supports the "hydraulic limitation hypothesis" that vegetation height interacted with climate change in affecting vegetation vulnerability. Our analysis highlighted the critical roles of different monsoon systems, climate condition and vegetation height in affecting ecosystem vulnerability. We suggest that the (sub)tropical forests in the Pacific monsoon region may have act as an important carbon sink during the past decades, while the tall forests in Southeast Tibetan mountains (a biodiversity center with high carbon stock) are highly vulnerable to climate change and should have priority in ecosystem protection.
中国西南地区是世界上重要的生物多样性热点地区，分别受太平洋和印度洋季风的控制。然而，非生物和生物因素如何影响不同季风区植被对气候变化的响应仍不清楚。在这里，我们利用 1982-2015 年生长季节归一化差异植被指数（NDVI 趋势）的年变化率来探讨中国西南地区植被（森林和灌木）对气候变化的脆弱性。我们研究了 NDVI 趋势与以下因素的关系：1）气候变化趋势，即由帕尔默干旱指数（PDSI）和潜在蒸散量（PET）分别表示的水分和能量可用性的年变化率；2）气候条件，即 1982-2015 年期间的平均 PDSI 和 PET；3）植被高度；4）生物群落类型；5）季风区。结果表明，NDVI 普遍在太平洋季风区增加，特别是在南部地区，这可能是因为在更具生产力的气候下生长的植被对气候变化的抵抗力更强，同时也因为气温降低导致蒸腾作用减少，从而缓解了该地区轻微的干旱趋势。相比之下，NDVI 普遍在印度洋季风区减少，该地区表现出更为明显的干旱趋势，特别是在青藏高原东南部的高亚高山和热带森林，这支持了“水力限制假说”，即植被高度与气候变化相互作用影响植被脆弱性。我们的分析强调了不同季风系统、气候条件和植被高度在影响生态系统脆弱性方面的关键作用。我们建议，太平洋季风区的（亚热带）森林在过去几十年可能已经成为一个重要的碳汇，而青藏高原东南部的高大森林（一个具有高碳储量的生物多样性中心）对气候变化高度敏感，应优先进行生态系统保护。
