Optimal white spruce breeding zones for Ontario under current and future climates

Optimal breeding zones were developed for white spruce (Picea glauca (Moench) Voss) in Ontario under present and future climate conditions to examine potential shifts due to climate change. These zones were developed by (i) determining a set of candidate breeding zones based on the relationship between measured performance variables and climate and (ii) employing a decision support model to select subsets of breeding zones that maximize geographic coverage subject to a constraint on the maximum number of zones. Current optimal breeding zones were based on 1961-1990 climate normals, and future breeding zones were based on three general circulation model (CGCM2, HADCM3, and CSIRO) predictions of 2041-2070 climate. Based on a maximum adaptive distance of 2.0 least significant difference values between sites within zones, 14 zones were required to cover the Ontario range of white spruce for the 1961-1990 data. Compared with breeding zones of other boreal conifers, current optimal breeding zones for white spruce were quite large, spanning up to 3° latitude and 10°-12° longitude and indicating large distances of effective seed transfer. Of the three general circulation models used to simulate future climate, HADCM3 B2 and CGCM2 B2 predicted 2041-2070 breeding zones that largely coincide with 1961-1990 zones. In contrast, CSIRO B2 indicated much narrower 2041-2070 breeding zones. Resume: Les auteurs ont determine des zones optimales damelioration de lepinette blanche (Picea glauca (Moench) Voss) en Ontario pour les conditions climatiques actuelles et futures afin dexaminer les modifications potentielles dues aux changements climatiques. Ces zones ont ete obtenues (i) en determinant un ensemble de zones candidates damelioration a partir des relations entre les variables de performance et le climat et (ii) en utilisant un modele daide a la decision pour choisir un sous-ensemble de zones damelioration maximisant la couverture geographique avec une contrainte quant au nombre maximal de zones. Les zones optimales actuelles damelioration etaient basees sur les normales climatiques de la periode 1961-1990. Les zones futures damelioration etaient basees sur les predictions de trois modeles de circulation generale (GCM2, HADCM3 et CSIRO) pour le climat de la periode 2041-2070. Avec la restriction que la distance reliee a ladaptation ne depasse pas deux fois la plus petite difference significative entre deux sites dune meme zone, 14 zones sont apparues necessaires pour representer adequatement la distribution de lepinette blanche en Ontario durant la periode 1961-1990. Comparativement aux zones damelioration des autres coniferes boreaux, les zones optimales actuelles dame--lioration pour lepinette blanche etaient relativement grandes, couvrant jusqua 3° de latitude et de 10° a 12° de longitude, impliquant de grandes distances pour le transfert effectif des semences. Parmi les trois modeles de circulation generale utilise s pour simuler le climat futur pour la periode 2041-2070, les modeles HADCM3 B2 et CGCM2 B2 predisaient des zones damelioration largement similaires a celles de la periode 1961-1990. A loppose, le modele CSIRO B2 predisait des zones damelioration beaucoup plus etroites. [Traduit par la Redaction]
Introduction Ensuring local adaptation of planted sources is of paramount concern in forest regeneration and tree improvement practices. Tree seeds planted outside of their environmental tolerance limits are unable to [...]