Multiscale ecology and dynamics of the forest-tundra ecotone

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The transition from forest to tundra in arctic and alpine regions - referred to as the 'forest-tundra ecotone' and punctuated by the upper limit of tree growth, known as 'treeline' - is expected to advance significantly as climate warming continues, with serious implications for biodiversity and earth-system processes. Research on the ecological processes that influence its dynamics, as well as responses to past climate change, is critical for improving forecasts of landscape change and understanding its ecological consequences. This program integrates field ecology with geospatial analysis to study the forest-tundra of northwestern Canada at multiple spatial and temporal scales. Research over the next five years will endeavour to answer two thematic questions: (1) How has the forest-tundra responded to climatic change and variability in the past?, and (2) What are the suite of physical and biological variables that influence the establishment and growth of trees and shrubs across the ecotone and, importantly, how do they interact to influence treeline dynamics? Investigations will focus on the altitudinal ecotone of southwest Yukon and the latitudinal ecotone of central Northwest Territories with the ancillary goal of comparing the two types of transitions. Methods and techniques range from plant-level measures of growth and physiology within experimental treatments, community-level investigations of population dynamics and species interactions, and landscape-scale measures of spatial pattern and ecosystem processes using remote sensing and GIS. Interdisciplinary training of students is a significant component of the research program. At least five Master's students and two Ph.D. students will be supported during the grant period and at least two undergraduate students will be hired annually as field and lab assistants. Individual projects are likely to focus on a specific scale and will act as the foundation of student training. The most novel scientific contribution of the program will be the integration of these projects in a hierarchical fashion to elucidate the cross-scale pattern-process relationships that create and shape ecotones and influence their dynamics.