Treeline ecotones are transition zones between closed forest and climatically tree-less, e.g. alpine or arctic, areas. Due to their climate sensitivity they are considered sentinels of global-change effects on terrestrial ecosystems. Vegetation patterns in treeline ecotones are constrained by multiple factors acting at different spatial and temporal scales. Climatic treeline positions are strongly influenced by global- and regional-scale climatic patterns, but other factors such as soil, meso-topography, and natural and anthropogenic disturbances dominate patterns at the landscape scale. Moreover, species competition/facilitation and micro-topographic heterogeneity are key factors for vegetation dynamics at finer scales. A current trend in vegetation dynamics both at latitudinal and altitudinal treelines is the accelerated encroachment of trees and shrubs, caused by interactions between climate and land-use changes. This encroachment can have far-reaching consequences for the biodiversity and functioning of mountain and subarctic ecosystems. Spatial vegetation patterns likely hold important information about the factors and processes (e.g. seed dispersal, safe-site characteristics, biotic interactions) that control this encroachment, yet only 5% of treeline research deals with the spatial component of patterns and processes. For this reason, it is crucial to improve our understanding of spatial processes and the spatial signals of global change impacts in treeline ecotones, in order to plan better adaptation strategies and monitor biodiversity trends in such sensitive ecosystems. To achieve this goal, there is a need for a multiscale and multidisciplinary approach to better link treeline metrics to ecological questions. Specifically, remote sensing (several platforms and sensors) can be combined with field data and modeling to capture the heterogeneity and variability of ecological conditions in treeline ecotones and couple observed spatial patterns to ecological processes. In this session, we invite contributions from all fields of research related to either the detection and description of treeline spatial and temporal patterns or the processes that may be relevant for these patterns.
BIOGEOSCIENCES Special Issue focused on observational (field and remote sensing) and modeling studies conducted along the extreme climatic and ecological gradients at the latitudinal and elevational treelines of the globe. We encourage submissions (original or review) from diverse disciplines including ecology (e.g. plant, forest, landscape), remote sensing, geography, geochemistry, microbiology, soil sciences, geomorphology, and climatology.