Characterization of the Regional Distribution Patterns of Shrubland Ecosystems from Responses to Climatic Controls using Multi-scale Remote Sensing Data in the Western United States

Abstract:

The spatial distribution patterns and response of terrestrial ecosystems to climatic controls vary depending on different land cover types, geographic location, and the relative influence of these feedbacks. Therefore understanding the long term relationship between land cover and climate variation over a large spatial extent is necessary. In this research, we studied the relationship between the spatial distribution of shrubland ecosystems and climate conditions of both temperature and precipitation in the western United States. The spatial distribution and cover intensities of shrubland ecosystems components including shrub, sagebrush, herbaceousness, and bare ground were quantified through the shrubland mapping project conducted by the USGS. The fractional cover of shrubland components were quantified through multiple scale modeling with regression tree models using both high-resolution WV-2 and Landsat 8 images. Climate records between 1980 and 2012 from Daymet were used to characterize regional climate condition into different climatic clusters following the spatial and temporal features of different climate variables. Subsequently, land cover data and the fractional cover of shrubland ecosystems components were employed to assess responses of different shrubbland ecosystem species to climate controls in different climate clusters. The spatial correlations between shrubland species and climate conditions reveals different responses of shrubland species to climatic controls through either warming-induced effects or moisture-induced effects. We also compared the response of fractional forest cover to climate controls in these climatic clusters. Our results explain the strengths of climate controls imposed by both temperature and precipitation. These analysis results provide insights into the fundamental relationship between shrubland species and climate controls.