Plant colonisation in the hight Arctic, a seed for change

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The rapidly changing arctic environment will alter the actual ecological balance (e.g. plant-herbivore relationships) and promote vegetation shifts.  In sparse high arctic vegetation, reproductive output is predicted to improve and increased plant establishment is expected. However, species response to change will also depend on the biotic interactions involved that can promote or prohibit plant growth and establishment.  My recent work revealed that facilitation increases plant establishment in cushion plants (mostly herbs) and biological soil crusts (herbs and shrubs) in the High Arctic. However, warming may lead to increased drought and competition limiting seedling establishment. Colonisation of open grounds by dominant shrub species is rare, yet it is essential for a substantial 'greening of the North' to take place.        Active in the Arctic since 1989, my long-term objective is to contribute to the ecological theory of vegetation dynamics. My short term objectives are to initiate the first large scale seed addition experiments with biological soil crust removal to test: 1) the relative importance of seed shortage and safe site limitation; and 2) the balance between competition and facilitation in plant colonisation in two contrasting nurse-protégé systems of the High Arctic.  These field experiments will include warming and watering treatments and address questions such as:  What prevent dominant vascular species (e.g. shrubs) establishment?  Will global change promote or decrease their recruitment? My work takes place near Pond Inlet (NU) around the Bylot Island research camp (73°N, 80°W).  My participation to this research group significantly reduces logistical costs and improves scientific interactions.  I plan to train 1 PhD, 2 MSc and a minimum of 4 BSc students with this project.  We will present annual reports on our research activities to the local communities and coordinate a winter visit in Yr 5 to allow more thorough exchanges on our results. First to address such theoretical and practical questions in this system, this work will be a significant contribution to the understanding, conservation and future management of Canada's northernmost biome.