Name
Microtopographic control on the spatial distribution of krummholz trees in an alpine environment.
Description
Treeline advancement, or the upslope migration of trees from forested areas into unforested, alpine or tundra ecosystems, has been observed in many locations around the world. Increased air temperatures due to climate change are expected to accelerate this migration because temperature is a major limiting factor on tree establishment and growth. Other limitations on tree establishment include a suitable growing medium, water availability, and seed source, but the role of microtopography remains poorly understood. In this study on an alpine basin in the Purcell Mountains of southeastern British Columbia, information derived from remotely sensed data was used to determine how the distribution of krummholz trees above treeline is influenced by microtopographic characteristics such as slope, curvature, roughness, and flow accumulation. Microtopographic characteristics were derived from a high-resolution digital elevation model created using LiDAR. Using multispectral imagery collected from a remotely piloted aircraft system, 598 trees were digitized across the alpine study area. An equal number of randomly selected, non-treed, snow free points were identified. Microtopographic characteristics were extracted for all treed and non-treed locations to assess the factors that influence tree establishment and growth. Some topographic variables, including slope and surface roughness, vary significantly between treed and non-treed locations. This research provides insight into the role of microtopography in alpine tree establishment and treeline advancement and could be used to inform spatially explicit modelling of treeline migration in the future.