The University of Montana Flathead Lake Biological Station, Polson, MT, 59860, USA; Numerical Terradynamic Simulation Group, The University of Montana, Missoula, MT, 59812, USA.
Glob Chang Biol. 2013 Oct;19(10):3111-22. doi: 10.1111/gcb.12288. Epub 2013 Aug 18.
The rate of vegetation recovery from boreal wildfire influences terrestrial carbon cycle processes and climate feedbacks by affecting the surface energy budget and land-atmosphere carbon exchange. Previous forest recovery assessments using satellite optical-infrared normalized difference vegetation index (NDVI) and tower CO(2) eddy covariance techniques indicate rapid vegetation recovery within 5-10 years, but these techniques are not directly sensitive to changes in vegetation biomass. Alternatively, the vegetation optical depth (VOD) parameter from satellite passive microwave remote sensing can detect changes in canopy biomass structure and may provide a useful metric of post-fire vegetation response to inform regional recovery assessments. We analyzed a multi-year (2003-2010) satellite VOD record from the NASA AMSR-E (Advanced Microwave Scanning Radiometer for EOS) sensor to estimate forest recovery trajectories for 14 large boreal fires from 2004 in Alaska and Canada. The VOD record indicated initial post-fire canopy biomass recovery within 3-7 years, lagging NDVI recovery by 1-5 years. The VOD lag was attributed to slower non-photosynthetic (woody) and photosynthetic (foliar) canopy biomass recovery, relative to the faster canopy greenness response indicated from the NDVI. The duration of VOD recovery to pre-burn conditions was also directly proportional (P < 0.01) to satellite (moderate resolution imaging spectroradiometer) estimated tree cover loss used as a metric of fire severity. Our results indicate that vegetation biomass recovery from boreal fire disturbance is generally slower than reported from previous assessments based solely on satellite optical-infrared remote sensing, while the VOD parameter enables more comprehensive assessments of boreal forest recovery.
从北方野火中恢复植被的速度会通过影响地表能量平衡和陆地-大气碳交换，影响陆地碳循环过程和气候反馈。以前使用卫星光学-红外归一化差异植被指数（NDVI）和塔台 CO2 涡度协方差技术对森林恢复的评估表明，植被在 5-10 年内会迅速恢复，但这些技术不能直接反映植被生物量的变化。相反，卫星被动微波遥感中的植被光学深度（VOD）参数可以检测冠层生物量结构的变化，并且可能是提供有用的指标，以了解火灾后植被对区域恢复评估的响应。我们分析了 NASA AMSR-E（EOS 高级微波扫描辐射计）传感器多年（2003-2010 年）的卫星 VOD 记录，以估算 2004 年阿拉斯加和加拿大的 14 场大型北方野火的森林恢复轨迹。VOD 记录表明，火灾后最初的树冠生物量在 3-7 年内恢复，比 NDVI 恢复滞后 1-5 年。VOD 滞后归因于非光合作用（木质）和光合作用（叶）树冠生物量的恢复速度较慢，与 NDVI 所表示的更快的树冠绿色响应相比。VOD 恢复到燃烧前条件的持续时间也与卫星（中分辨率成像光谱仪）估计的树木覆盖损失直接成正比（P < 0.01），作为火灾严重程度的指标。我们的结果表明，与以前仅基于卫星光学-红外遥感的评估相比，北方火灾干扰后植被生物量的恢复速度通常较慢，而 VOD 参数可以更全面地评估北方森林的恢复。
