title: Ecological gradients driving the distribution of four Ericaceae in boreal Quebec, Canada.
abstract: Understory species play a significant role in forest ecosystem dynamics. As such, species of the Ericaceae family have a major effect on the regeneration of tree species in boreal ecosystems. It is thus imperative to understand the ecological gradients controlling their distribution and abundance, so that their impacts can be taken into account in sustainable forest management. Using innovative analytical techniques from landscape ecology, we aimed to position, along ecological gradients, four Ericaceae found in the boreal forest of Quebec (Canada) (Rhododendron groenlandicum, Kalmia angustifolia, Chamaedaphne calyculata, and Vaccinium spp), to regionalize these species into landscape units relevant to forest management, and to estimate the relative importance of several ecological drivers (climate, disturbances, stand attributes, and physical environment) that control the species distribution and abundance. We conducted our study in boreal Quebec, over a study area covering 535,355 km(2). We used data from 15,339 ecological survey plots and forest maps to characterize 1422 ecological districts covering the study region. We evaluated the relative proportion of each ericaceous species and explanatory variables at the district level. Vegetation and explanatory variables matrices were used to conduct redundancy, cluster, and variation partitioning analyses. We observed that ericaceous species are mainly distributed in the western part of the study area and each species has a distinct latitudinal and longitudinal gradient distribution. On the basis of these gradients, we delimited 10 homogeneous landscape units distinct in terms of ericaceous species abundance and environmental drivers. The distribution of the ericaceous species along ecological gradients is closely related to the overlaps between the four sets of explanatory variables considered. We conclude that the studied Ericaceae occupy specific positions along ecological gradients and possess a specific abundance and distribution controlled by the integration of multiple explanatory variables.
authors.affiliation: Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec 2700 rue Einstein, Québec, G1P 3W8, Quebec, Canada ; Centre d'étude de la forêt, Faculté de foresterie, de géographie et de géomatique, Université Laval 2405 rue de la Terrasse, Québec, G1V 0A6, Quebec, Canada.
authors.forename: Nelson
authors.initials: N
authors.lastname: Thiffault
authors.affiliation: Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec 2700 rue Einstein, Québec, G1P 3W8, Quebec, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Grondin
authors.affiliation: Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec 2700 rue Einstein, Québec, G1P 3W8, Quebec, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Noël
authors.affiliation: Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec 2700 rue Einstein, Québec, G1P 3W8, Quebec, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Poirier
keywords: Boreal forest; Chamaedaphne calyculata; Kalmia angustifolia; Rhododendron groenlandicum; Vaccinium angustifolium; Vaccinium myrtilloides; ecological drivers; landscape ecology; redundancy analysis