气候引起的树木死亡数量被大规模和长期绿化所掩盖
Yuchao Yan1, Shilong Piao2,3, William M Hammond4
1Institute of Carbon Neutrality, Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing, China.
Nature ecology & evolution
|March 12, 2024
概括
严重的树木死亡事件对植被绿色的局部影响,通常被更广泛的绿化趋势所掩盖. 空间和时间尺度对于理解气候变化对森林的影响至关重要.
科学领域:
- 生态生态学 生态生态学
- 遥感 遥感 遥感 遥感
- 气候变化科学 气候变化科学
背景情况:
- 植被绿化是一个广泛的趋势,但与干旱和热浪等气候极端相关的严重树木死亡事件越来越多.
- 这些突然的树木死亡事件对不同规模的整体植被绿色的影响仍然不清楚.
研究的目的:
- 调查气候引起的严重树木死亡事件对植被绿色的影响程度.
- 通过各种空间分辨率和时间延伸来分析这些影响.
主要方法:
- 分析了三个基于卫星的受损生长季节正常化差异植被指数 (NDVIGS) 数据集.
- 利用了来自全球1,303个现场记录的地点的数据,这些地点正在经历严重的干旱或热量诱导的树木死亡.
- 检查的NDVIGS异常 (ΔNDVI) 在空间分辨率从30米到8公里.
主要成果:
- 严重的树木死亡事件每年都会对NDVIGS产生明显但局部的负面影响,这些负面影响在较粗的分辨率 (250米,8公里) 上会被掩盖.
- 在30米分辨率下,NDVIGS的减少与本地物种丰富度和森林高度有负相关.
- 地形异质性显著影响空间尺度上的 ΔNDVI 差异.
- 长期 (十年+) 分析始终显示绿化在所有空间分辨率中占主导地位.
结论:
- 严重的树木死亡率对植被绿色的局部印记取决于规模,通常被更广泛的绿化趋势掩盖.
- 空间时间尺度对于准确了解气候变化对森林生产力和死亡率的影响至关重要.
- 绿化趋势在较长时间内主导着森林动态,尽管发生了突然死亡事件.
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