Extensive land cover change across Arctic-Boreal Northwestern North America from disturbance and climate forcing
Extensive land cover change across Arctic-Boreal Northwestern North America from disturbance and climate forcing
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DOI：
10.1111/gcb.14804
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发表时间：
2019-09-17
影响因子：
11.6
通讯作者：
Friedl, Mark A.
中科院分区：
文献类型：
--
作者：
Wang, Jonathan A.;Sulla-Menashe, Damien;Friedl, Mark A.
大量的干扰因素，如野火，土地利用，和气候驱动的木本灌木的扩张，正在改变整个北极-北方生态系统的植物功能类型的分布，这对陆地生态系统和气候之间的相互作用和反馈在北方高纬度地区具有重要意义。然而，由于现有的土地覆盖数据集的空间分辨率太粗糙，大规模的土地覆盖变化在北极-北方地区（ABR）的特点一直很差。在这里，我们使用31年（1984-2014）的中等空间分辨率（30米）卫星图像，覆盖阿拉斯加和加拿大西北部4.7 x 10（6）km（2）的区域，以表征区域尺度的ABR土地覆盖变化。我们发现，13.6 +/- 1.3%的域已经改变，主要是通过两种主要的转换模式：（a）同时干扰驱动的减少，在万年青森林面积（与1984年相比-14.7 +/-3.0%）和落叶林面积增加（B）北极生物群落中气候驱动的草本和灌木植被扩张（+7.4 +/-2.0%）。通过使用30米图像的时间序列，我们描述了由于火灾、收获和气候引起的生长而在相对较短的空间尺度（数百米）上发生的森林和灌木覆盖的动态，这些动态在粗空间分辨率下无法观察到（例如，500米或更大的像素大小）图像。野火造成了大部分的万年青林损失和万年青林增加以及大量的落叶林增加。在多个空间尺度上植物功能类型分布的广泛变化是一致的大气CO2的季节性和生态系统生产力增加的观测在北方高纬度和信号大陆尺度的变化，在结构和功能的北方高纬度生态系统，以应对气候变化。
A multitude of disturbance agents, such as wildfires, land use, and climate-driven expansion of woody shrubs, is transforming the distribution of plant functional types across Arctic-Boreal ecosystems, which has significant implications for interactions and feedbacks between terrestrial ecosystems and climate in the northern high-latitude. However, because the spatial resolution of existing land cover datasets is too coarse, large-scale land cover changes in the Arctic-Boreal region (ABR) have been poorly characterized. Here, we use 31 years (1984-2014) of moderate spatial resolution (30 m) satellite imagery over a region spanning 4.7 x 10(6) km(2) in Alaska and northwestern Canada to characterize regional-scale ABR land cover changes. We find that 13.6 +/- 1.3% of the domain has changed, primarily via two major modes of transformation: (a) simultaneous disturbance-driven decreases in Evergreen Forest area (-14.7 +/- 3.0% relative to 1984) and increases in Deciduous Forest area (+14.8 +/- 5.2%) in the Boreal biome; and (b) climate-driven expansion of Herbaceous and Shrub vegetation (+7.4 +/- 2.0%) in the Arctic biome. By using time series of 30 m imagery, we characterize dynamics in forest and shrub cover occurring at relatively short spatial scales (hundreds of meters) due to fires, harvest, and climate-induced growth that are not observable in coarse spatial resolution (e.g., 500 m or greater pixel size) imagery. Wildfires caused most of Evergreen Forest Loss and Evergreen Forest Gain and substantial areas of Deciduous Forest Gain. Extensive shifts in the distribution of plant functional types at multiple spatial scales are consistent with observations of increased atmospheric CO2 seasonality and ecosystem productivity at northern high-latitudes and signal continental-scale shifts in the structure and function of northern high-latitude ecosystems in response to climate change.