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Biophysical controls of increased tundra productivity in the western Canadian Arctic
Remote Sensing of Environment ( IF 11.1 ) Pub Date : 2021-03-07 , DOI: 10.1016/j.rse.2021.112358
Angel Chen , Trevor C. Lantz , Txomin Hermosilla , Michael A. Wulder

Rapid climate warming has widely been considered as the main driver of recent increases in Arctic tundra productivity. Field observations and remote sensing both show that tundra “greening” has been widespread, but heterogeneity in regional and landscape-scale trends suggest that additional controls are mediating the response of tundra vegetation to warming. In this study, we examined the relationship between changes in vegetation productivity in the western Canadian Arctic and biophysical variables by analyzing trends in the Enhanced Vegetation Index (EVI) obtained from nonparametric regression of annual Landsat surface reflectance composites. We used Random Forests classification and regression tree modelling to predict the trajectory and magnitude of greening from 1984 to 2016 and identify biophysical controls. More than two-thirds of our study area showed statistically significant increases in vegetation productivity, but observed changes were heterogeneous, occurring most rapidly within areas of the Southern Arctic that were: (1) dominated by dwarf and upright shrub cover types, (2) moderately sloping, and (3) located at lower elevation. These findings suggest that the response of tundra vegetation to warming is mediated by regional- and landscape-scale variation in microclimate, topography and soil moisture, and physiological differences among plant functional groups. Our work highlights the potential of the joint analysis of annual remotely sensed vegetation indices and broad-scale biophysical data to understand spatial variation in tundra vegetation change.



中文翻译:

在加拿大西部北极地区提高苔原生产力的生物物理控制

快速的气候变暖已被广泛认为是北极苔原生产力最近增加的主要驱动力。实地观察和遥感都表明,苔原的“绿化”已经很普遍,但是区域和景观尺度趋势的异质性表明,附加的控制措施正在调节苔原植被对变暖的响应。在这项研究中,我们通过分析从年度Landsat表面反射率复合材料的非参数回归获得的增强植被指数(EVI)的趋势,研究了加拿大西部北极地区植被生产力的变化与生物物理变量之间的关系。我们使用随机森林分类和回归树模型来预测1984年至2016年的绿化轨迹和绿化程度,并确定生物物理控制方法。我们研究区域的三分之二以上显示出植被生产力的统计显着提高,但观察到的变化是异质的,在南北极地区以最快的速度发生:(1)以矮化和直立灌木覆盖类型为主,(2)适度倾斜,并且(3)位于较低的高度。这些发现表明,苔原植被对变暖的反应是由微气候,地形和土壤湿度的区域和景观尺度变化以及植物功能群之间的生理差异介导的。我们的工作强调了对年度遥感植被指数和大规模生物物理数据进行联合分析以了解苔原植被变化的空间变化的潜力。但是观察到的变化是不均匀的,在南北极地区发生得最快,这些变化是:(1)以矮化和直立灌木覆盖类型为主;(2)中度倾斜;(3)位于较低海拔。这些发现表明,苔原植被对变暖的反应是由微气候,地形和土壤湿度的区域和景观尺度变化以及植物功能群之间的生理差异介导的。我们的工作强调了对年度遥感植被指数和大规模生物物理数据进行联合分析以了解苔原植被变化的空间变化的潜力。但是观察到的变化是不均匀的,在南北极地区发生得最快,这些变化是:(1)以矮化和直立灌木覆盖类型为主;(2)中度倾斜;(3)位于较低海拔。这些发现表明,苔原植被对变暖的反应是由微气候,地形和土壤湿度的区域和景观尺度变化以及植物功能群之间的生理差异介导的。我们的工作强调了对年度遥感植被指数和大规模生物物理数据进行联合分析以了解苔原植被变化的空间变化的潜力。(3)位于较低高度。这些发现表明,苔原植被对变暖的反应是由微气候,地形和土壤湿度的区域和景观尺度变化以及植物功能群之间的生理差异介导的。我们的工作强调了对年度遥感植被指数和大规模生物物理数据进行联合分析以了解苔原植被变化的空间变化的潜力。(3)位于较低高度。这些发现表明,苔原植被对变暖的反应是由微气候,地形和土壤湿度的区域和景观尺度变化以及植物功能群之间的生理差异介导的。我们的工作强调了对年度遥感植被指数和大规模生物物理数据进行联合分析以了解苔原植被变化的空间变化的潜力。

更新日期:2021-03-07
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