Response of African humid tropical forests to recent rainfall anomalies
Response of African humid tropical forests to recent rainfall anomalies
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DOI：
10.1098/rstb.2012.0306
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发表时间：
2013-09-05
影响因子：
6.3
通讯作者：
Saatchi, Sassan
中科院分区：
文献类型：
--
作者：
Asefi-Najafabady, Salvi;Saatchi, Sassan
在过去的十年中，热带大西洋海面温度升高导致强烈的负降雨异常，导致亚马逊西部雨林发生大面积干旱，对森林冠层产生持续影响。相比之下，尽管同期出现了大规模干旱和降雨异常，但西非和中非的雨林在同一时期并未受到重大影响。结合气候研究单位气象站（CRU；1950-2009）的降雨观测和热带降雨测量任务（TRMM；1998-2010）的卫星观测，我们发现西非和中非在过去十年中经历了强烈的负缺水（WD）异常，特别是在 2005 年、2006 年和 2007 年。这些异常是非洲日益干旱趋势的延续。地区 始于 20 世纪 70 年代。我们通过分析来自 QuickSCAT (1999-2009) 对树冠含水量和结构变化敏感的微波散射仪数据，监测了森林对过去十年极端降雨异常的响应。与亚马逊流域不同，我们没有发现极端干旱事件对中部非洲的森林产生重大影响，这表明这些森林对短期严重干旱具有潜在的适应性。只有西非稀树草原边界附近的森林和刚果盆地北部支离破碎的景观中的森林才能应对极端干旱，造成广泛的树冠干扰，这种干扰仅在西非期间持续。 CRU 和 TRMM 数据的时间序列分析显示，中非和西非的大部分地区都经历了季节性或十年间的极端温差（小于 2600 毫米）。我们假设，20世纪70年代长期的历史极端干旱和逐渐干燥的趋势增加了非洲潮湿热带森林对干旱的适应性。
During the last decade, strong negative rainfall anomalies resulting from increased sea surface temperature in the tropical Atlantic have caused extensive droughts in rainforests of western Amazonia, exerting persistent effects on the forest canopy. In contrast, there have been no significant impacts on rainforests of West and Central Africa during the same period, despite large-scale droughts and rainfall anomalies during the same period. Using a combination of rainfall observations from meteorological stations from the Climate Research Unit (CRU; 1950-2009) and satellite observations of the Tropical Rainfall Measuring Mission (TRMM; 1998-2010), we show that West and Central Africa experienced strong negative water deficit (WD) anomalies over the last decade, particularly in 2005, 2006 and 2007. These anomalies were a continuation of an increasing drying trend in the region that started in the 1970s. We monitored the response of forests to extreme rainfall anomalies of the past decade by analysing the microwave scatterometer data from QuickSCAT (1999-2009) sensitive to variations in canopy water content and structure. Unlike in Amazonia, we found no significant impacts of extreme WD events on forests of Central Africa, suggesting potential adaptability of these forests to short-term severe droughts. Only forests near the savanna boundary in West Africa and in fragmented landscapes of the northern Congo Basin responded to extreme droughts with widespread canopy disturbance that lasted only during the period of WD. Time-series analyses of CRU and TRMM data show most regions in Central and West Africa experience seasonal or decadal extreme WDs (less than 2600 mm). We hypothesize that the long-term historical extreme WDs with gradual drying trends in the 1970s have increased the adaptability of humid tropical forests in Africa to droughts.