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在干旱季节,亚马逊森林保持着一致的树冠结构和绿色

Douglas C Morton¹, Jyoteshwar Nagol², Claudia C Carabajal³

¹NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.

|February 7, 2014

概括

亚马逊森林的季节性绿化是一个由太阳传感器几何学引起的光学错觉,而不是植物生长的增加. 纠正这个文物揭示了稳定的森林结构,挑战光限生产力理论.

科学领域:

生态学和遥感技术的发展
热带森林的动态热带森林的动态
生物圈与大气层的相互作用

背景情况:

热带森林净初级产量由阳光和降雨季节性调节.
之前的研究表明光线限制,支持卫星观察到亚马逊的干旱季绿化.
这种现象意味着干旱期间森林增长有所增加.

研究的目的:

研究在亚马逊热带雨林中观察到的季节性绿化背后的机制.
评估叶面积和叶子反射率变化在这种现象中的作用.
为了确定光学遥感数据是否准确地反映了森林生产力的实际变化.

主要方法:

利用复杂的辐射转移模型来模拟森林树冠反射率.
使用激光雷达和光学传感器的独立卫星观测进行验证.
分析了与太阳传感器几何相关的双向反射效应.

主要成果:

显而易见的季节性绿化被认为是由于太阳传感器几何变化而改变近红外反射率的工件.
对双向反射效应的校正消除了表面反射效应的季节性变化.
激光雷达的观测和模型模拟显示了整个季节的树冠特性稳定.

结论:

亚马逊森林结构和反射力的稳定性挑战了光限生产率和干旱增强增长的范式.
光学遥感数据需要对太阳传感器几何文物进行校正,以准确评估植被反应.
准确的校正对于理解全球植被对气候变化的反应至关重要.

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