The light-deficient climates of western Central African evergreen forests
The light-deficient climates of western Central African evergreen forests
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中非西部常绿森林的缺光气候
DOI：
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发表时间：
2019
影响因子：
6.7
通讯作者：
A. Ngomanda
中科院分区：
文献类型：
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作者：
N. Philippon;Guillaume Cornu;L. Monteil;V. Gond;V. Moron;J. Pergaud;G. Seze;S. Bigot;P. Camberlin;C. Doumenge;A. Fayolle;A. Ngomanda
中非森林生长的降雨阈值低于亚马逊河流域和东南亚。因此，经常注意降雨量，因为降雨量的季节性和年际变化控制着中非森林的水平衡和光合作用。尽管如此，人们也认识到，光的供应是热带森林的一个关键因素。因此，本研究旨在探索中非地区普遍存在的光照条件及其对森林特征的潜在影响。使用卫星估计每小时的辐照度，我们发现，首先，四种主要类型的提取的辐照度的日周期转化为不同水平的降雨量，蒸散量，直接和漫射光。然后占昼夜周期和年度周期之间的规模相互作用，我们表明，在年度周期期间，在整个中非森林的光的每日数量和质量有很大的不同：特别是在主要的干旱季节，强烈的光缺乏的气候，特别是在中部非洲西部和加蓬的独特性，指出。最后，使用原始的陆地森林地图，我们还表明，大多数万年青森林位于中非西部和加蓬。我们假设，尽管平均年降水量低于2000 mm yr−1，但中非西部的光缺乏气候可以庇护万年青森林，因为在6月至9月的主要旱季期间，广泛的低层云量发展，这大大减少了对水的需求，并提高了树木光合作用的光质量。这些发现为进一步分析中非西部光照不足气候的过去和未来变化以及万年青森林对这些变化的脆弱性铺平了道路。
Rainfall thresholds under which forests grow in Central Africa are lower than those of Amazonia and southeast Asia. Attention is thus regularly paid to rainfall whose seasonality and interannual variability has been shown to control Central African forests’ water balance and photosynthetic activity. Nonetheless, light availability is also recognized as a key factor to tropical forests. Therefore this study aims to explore the light conditions prevailing across Central Africa, and their potential impact on forests’ traits. Using satellite estimates of hourly irradiance, we find first that the four main types of diurnal cycles of irradiance extracted translate into different levels of rainfall, evapotranspiration, direct and diffuse light. Then accounting for scale interactions between the diurnal and annual cycles, we show that the daily quantity and quality of light considerably vary across Central African forests during the annual cycle: the uniqueness of western Central Africa and Gabon in particular, with strongly light-deficient climates especially during the main dry season, points out. Lastly, using an original map of terra firme forests, we also show that most of the evergreen forests are located in western Central Africa and Gabon. We postulate that despite mean annual precipitation below 2000 mm yr−1, the light-deficient climates of western Central Africa can harbour evergreen forests because of an extensive low-level cloudiness developing during the June–September main dry season, which strongly reduces the water demand and enhances the quality of light available for tree photosynthesis. These findings pave the way for further analyses of the past and future changes in the light-deficient climates of western Central Africa and the vulnerability of evergreen forests to these changes.
影响因子：
5.2
作者：
A. Rap;D. Spracklen;L. Mercado;C. Reddington;J. Haywood;R. Ellis;O. Phillips;P. Artaxo;D. Bonal;N. R. Coupe;N. Butt
通讯作者：
A. Rap;D. Spracklen;L. Mercado;C. Reddington;J. Haywood;R. Ellis;O. Phillips;P. Artaxo;D. Bonal;N. R. Coupe;N. Butt