title: Fine-scale geographic variation in photosynthetic-related traits of Picea glauca seedlings indicates local adaptation to climate.
abstract: Climate-related variations in functional traits of boreal tree species can result both from physiological acclimation and genetic adaptation of local populations to their biophysical environment. To improve our understanding and prediction of the physiological and growth responses of populations to climate change, we studied the role of climate of seed origin in determining variations in functional traits and its implications for tree improvement programs for a commonly reforested boreal conifer, white spruce (Picea glauca (Moench) Voss). We evaluated growth, root-to-shoot ratio (R/S), specific leaf area (SLA), needle nitrogen (N(mass)), total non-structural carbohydrates (NSC) and photosynthetic traits of 3-year-old seedlings in a greenhouse experiment using seed from six seed orchards (SO) representing the different regions where white spruce is reforested in Québec. Height and total dry mass (TDM) were positively correlated with photosynthetic capacity (A(max)), stomatal conductance (g(s)) and mesophyll conductance (g(m)). Total dry mass, but not height growth, was strongly correlated with latitude of seed origin (SO) and associated climate variables. A(max), g(s), g(m) and more marginally, photosynthetic nitrogen-use efficiency (PNUE) were positively associated with the mean July temperature of the SO, while water use efficiency (WUE) was negatively associated. Maximum rates of carboxylation (V(cmax)), maximum rates of electron transport (J(max)), SLA, N(mass), NSC and R/S showed no pattern. Our results did not demonstrate a higher Amax for northern seed orchards, although this has been previously hypothesized as an adaptation mechanism for maintaining carbon uptake in northern regions. We suggest that gs, gm, WUE and PNUE are the functional traits most associated with fine-scale geographic clines and with the degree of local adaptation of white spruce populations to their biophysical environments. These geographic patterns may reflect in situ adaptive genetic differences in photosynthetic efficiency along the cline.
authors.affiliation: Centre d'étude de la forêt, Faculté de foresterie, de géographie et de géomatique, Pavillon Abitibi Price, Université Laval, Québec, QC, Canada G1V 0A6 lahcen.benomar.1@ulaval.ca.
authors.forename: Lahcen
authors.initials: L
authors.lastname: Benomar
authors.affiliation: Direction de la recherche forestière, ministère des Forêts, de la Faune et des Parcs, 2700 rue Einstein, Québec, QC, Canada G1P 3W8.
authors.forename: Mohammed S
authors.initials: MS
authors.lastname: Lamhamedi
authors.affiliation: Centre d'étude de la forêt, Faculté de foresterie, de géographie et de géomatique, Pavillon Abitibi Price, Université Laval, Québec, QC, Canada G1V 0A6.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Villeneuve
authors.affiliation: Direction de la recherche forestière, ministère des Forêts, de la Faune et des Parcs, 2700 rue Einstein, Québec, QC, Canada G1P 3W8.
authors.forename: André
authors.initials: A
authors.lastname: Rainville
authors.affiliation: Natural Resources Canada, Canadian Forest Service, Canadian Wood Fibre Centre, 1055 rue du P.E.P.S., PO Box 10380, Stn Sainte Foy, Québec, QC, Canada G1V 4C7.
authors.forename: Jean
authors.initials: J
authors.lastname: Beaulieu
authors.affiliation: Centre d'étude de la forêt, Faculté de foresterie, de géographie et de géomatique, Pavillon Abitibi Price, Université Laval, Québec, QC, Canada G1V 0A6.
authors.forename: Jean
authors.initials: J
authors.lastname: Bousquet
authors.affiliation: Centre d'étude de la forêt, Faculté de foresterie, de géographie et de géomatique, Pavillon Abitibi Price, Université Laval, Québec, QC, Canada G1V 0A6.
authors.forename: Hank A
authors.initials: HA
authors.lastname: Margolis
mesh_terms: D000064:Acclimatization; D002244:Carbon / Q000378:metabolism; D002980:Climate; D057231:Climate Change; D004579:Electron Transport; D005843:Geography; D058503:Mesophyll Cells / Q000502:physiology; D010788:Photosynthesis / Q000502:physiology; D028222:Picea / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology; D018517:Plant Roots / Q000502:physiology; D018520:Plant Shoots / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology; D011792:Quebec; D036226:Seedlings / Q000502:physiology*; D013696:Temperature; D014197:Trees; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water; D002244:Carbon
keywords: adaptation; climate change; mesophyll conductance; photosynthesis; white spruce