Key message This work analyses the rate of recovery of the spectral signal from clearcut areas of coppice Mediterranean forests using Landsat Time Series (LTS). The analysis revealed a more rapid rate of spectral signal recovery than what was found in previous investigations in boreal and temperate forests. Context The rate of post-disturbance vegetation recovery is an important component of forest dynamics. Aims In this study, we analyze the recovery of the spectral signal from forest clearcut areas in Mediterranean conditions when the coppice system of forest management is applied. Methods We used LTS surface reflectance data (1999–2015).We generated an annual reference database of clearcuts using visual interpretation and local forest inventory data, and then derived the Normalized Difference Vegetation Index (NDVI) and Normalized Burn Ratio (NBR) spectral trajectories for these clearcuts. From these spectral trajectories, we calculated the Years to Recovery or Y2R, the number of years it takes for a pixel to return to within a specified threshold (i.e., 70%, 80%, 90%, 100%) of its pre-disturbance value. Spectral recovery rates were then corroborated using measures of canopy height derived from airborne laser scanning (ALS) data. Results The coppice system is associated with rapid recovery rates when compared to rates of recovery from seeds or seedlings in temperate and boreal forest conditions. We found that the Y2R derived from the spectral trajectories of post-clearcut NBR and NDVI provided similar characterizations of rapid recovery for the coppice system of forest management applied in our study area. The ALS measures of canopy height indicated that the Y2R metric accurately captured the rapid regeneration of coppice systems. Conclusion The rapid rate of spectral recovery associated with the coppice system is 2–4 years, which contrasts with values reported in boreal and temperate forest environments, where spectral recovery was attained in approximately 10 years. NBR is an effective index for assessing rapid recovery in this forest system.

中文翻译：

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使用 Landsat 时间序列监测地中海矮林的砍伐和随后的快速恢复

关键信息 这项工作使用 Landsat 时间序列 (LTS) 分析了地中海丛林森林砍伐区域的光谱信号恢复率。分析表明，频谱信号恢复速度比之前在北方和温带森林中进行的调查发现的速度更快。背景 干扰后植被恢复的速度是森林动态的一个重要组成部分。目的 在这项研究中，我们分析了在应用森林管理的丛林系统时地中海条件下森林砍伐区域的光谱信号的恢复。方法 我们使用了 LTS 表面反射率数据（1999-2015）。我们使用视觉解释和当地森林清单数据生成了一个年度砍伐参考数据库，然后为这些清除地推导出归一化差异植被指数 (NDVI) 和归一化燃烧率 (NBR) 光谱轨迹。根据这些光谱轨迹，我们计算了恢复年数或 Y2R，即像素恢复到其扰动前的指定阈值（即 70%、80%、90%、100%）内所需的年数价值。然后使用从机载激光扫描 (ALS) 数据得出的冠层高度测量值来证实光谱恢复率。结果与温带和北方森林条件下种子或幼苗的恢复率相比，矮林系统与快速恢复率相关。我们发现，从砍伐后 NBR 和 NDVI 的光谱轨迹得出的 Y2R 为我们研究区应用的林木管理系统提供了类似的快速恢复特征。冠层高度的 ALS 测量表明 Y2R 度量准确地捕获了林木系统的快速再生。结论 与林木系统相关的光谱恢复的快速速率为 2-4 年，这与在北方和温带森林环境中报告的值形成对比，后者在大约 10 年内实现光谱恢复。NBR 是评估该森林系统快速恢复的有效指标。结论 与林木系统相关的光谱恢复的快速速率为 2-4 年，这与在北方和温带森林环境中报告的值形成对比，后者在大约 10 年内实现光谱恢复。NBR 是评估该森林系统快速恢复的有效指标。结论 与林木系统相关的光谱恢复的快速速率为 2-4 年，这与在北方和温带森林环境中报告的值形成对比，后者在大约 10 年内实现光谱恢复。NBR 是评估该森林系统快速恢复的有效指标。