The disturbance and recovery cycles of Canadian boreal forests result in highly dynamic landscapes, requiring continued monitoring to observe and characterize environmental change over time. Well-established remote sensing methods capture change over forested ecosystems, however the return of forest vegetation in disturbed locations is infrequently documented and not well understood. Landsat time-series data allows for both the capture of the initial disturbance and the ability to monitor the subsequent vegetation regeneration with spectral vegetation indices. In this research, we used three spectral recovery metrics derived from an annual Landsat-based per-pixel Normalized Burn Ratio time series to determine trends in the short-term rates of spectral recovery for areas disturbed by wildfire (1986–2006), as assessed using a series of 5-year post-disturbance windows to observe forest recovery trends. Our results indicated that rates of spectral forest recovery vary over time and space in the Taiga and Boreal Shield ecozones. We found evidence that post-fire spectral forest recovery rates have accelerated over time in both the East and West Taiga Shield ecozones, with a consistent, positive, and significant trend measured using a Mann-Kendall test for monotonicity and Theil-Sen slope estimation. Over the analysis period (1986–2011), relative rates of spectral forest recovery increased by 18% in the Taiga Shield East and 9% in the Taiga Shield West. In contrast, spectral forest recovery rates in the Boreal Shield varied temporally, and were not consistently positive or negative. These results demonstrate that post-fire spectral recovery rates are not fixed over time and that spectral trends are dependent upon spatial location in the Canadian boreal. This retrospective baseline information on trends in spectral recovery rates highlights the value of, and continued need for detailed monitoring of vegetation regeneration in boreal forest ecosystems, particularly in the context of a changing climate.

中文翻译：

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分析来自 Landsat 时间序列的火灾后植被恢复短期速率的时空变异性

加拿大北方森林的干扰和恢复周期导致了高度动态的景观，需要持续监测以观察和表征环境随时间的变化。完善的遥感方法可以捕捉森林生态系统的变化，但很少记录和了解受干扰地区森林植被的恢复。Landsat 时间序列数据既可以捕获初始扰动，也可以使用光谱植被指数监测随后的植被更新。在这项研究中，我们使用了三个光谱恢复指标，这些指标来源于每年基于 Landsat 的每像素归一化燃烧率时间序列，以确定受野火干扰的地区（1986-2006）短期光谱恢复率的趋势，使用一系列 5 年干扰后窗口来观察森林恢复趋势进行评估。我们的结果表明，在针叶林和北方盾构生态区中，光谱森林恢复率随时间和空间而变化。我们发现有证据表明，东针叶林地盾生态区和西针叶林生态区的火灾后光谱森林恢复率随着时间的推移而加速，使用 Mann-Kendall 检验单调性和 Theil-Sen 坡度估计测量出一致、积极和显着的趋势。在分析期间（1986-2011 年），针叶林地盾东的光谱森林恢复的相对速率增加了 18%，针叶林地盾西的光谱森林恢复率增加了 9%。相比之下，Boreal Shield 中的光谱森林恢复率随时间变化，并且并非始终为正或负。这些结果表明，火灾后的光谱恢复率不是随时间固定的，光谱趋势取决于加拿大北方的空间位置。这种关于光谱恢复率趋势的回顾性基线信息突出了对北方森林生态系统中植被再生进行详细监测的价值和持续需要，特别是在气候变化的背景下。