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Using height growth to model local and regional response of trembling aspen (Populus tremuloides Michx.) to climate within the boreal forest of western Québec

Summary

Published in Ecological Modelling 243: 123-132

Studies relating site index to climatic variables basically assume that the sensitivity of a species to climate remains stable across the geographic range of their study area. Yet, provenance trials speak to the contrary and show that populations are adapted to their local climatic conditions and tend to respond differently to climate. Spatial and temporal complexity of forest productivity and climate-relationships has been globally reported and recent studies have emphasized the necessity for regional studies on forest growth dynamics of current and future populations. The objective of this study was to determine whether the main climatic and non-climatic drivers of trembling aspen (Populus tremuloides Michx.) growth in Québec should be treated as regional (the study area reacts as a unique population) or local factors (the area is composed of different populations) when modeling the spatio-temporal variability of aspen productivity as measured with site index. Stem analysis data was collected from 124 trees (32 stands) that span a north-south (latitude 46–51◦N) transect in western boreal Québec. Most stands were dense with cover density above 60%, even-aged, 50–90 years old, and very often mixed. The northernmost regions (latitude 48–51◦N) are characterized by either organic or clay deposits, while in the south (latitude 46–48◦N) till or clay deposits predominate. Climate variables that met selection criteria as major regional or local factors that influence aspen productivity were selected. A mixed modeling approach was subsequently employed to identify the categorization unit that could be defined as a population. We then predicted variation in the random error with prior information obtained at stand level. Our results show that aspen height growth is mainly driven by annual sums of degree days and stand age. Surface deposit type, which is an indicator of soil nutritive status and moisture potential, was found to have modulated climate influence. Finally, aspen productivity is better explained with a model that assumes that specific populations have a different response function to climate and are adapted to their local climatic conditions. This has implications when predicting the response to climatic change for forest growth models that assume that conspecifics respond to climate similarly.

Sector(s): 

Forests

Categorie(s): 

Scientific Article

Theme(s): 

Forestry Research, Forests, Silviculture

Author(s)

ANYOMI, Kenneth A., Frédéric RAULIER, Daniel MAILLY, Martin P. GIRARDIN and Yves BERGERON

Year of publication :

2012

Format :

Paper

Keywords :

indice de qualité de station, peuplier faux-tremble, modèle de population, climat, sol, Populus tremuloides, article scientifique de recherche forestière, sylviculture et rendement des forêts naturelles - peuplements feuillus, sylviculture et rendement des forêts naturelles - peuplements mélangés, sylviculture et rendement des forêts naturelles - peuplements résineux, silviculture and yield of natural forests - hardwood stands, silviculture and yield of natural forests - mixed stands, silviculture and yield of natural forests - softwood stands, site index, trembling aspen, population model, climate, soil

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