Radial growth in Pinus contorta relative to changing climate patterns in British Columbia: Genetic response to annual climate variations, Sierra Curtis-McLane 1, Sally Aitken 1 1. Department of Forest Sciences, University of British Columbia, Vancouver, BC V6T1Z1; Introduction The unprecedented rate of climate change that occurred during the twentieth century is projected to continue throughout and beyond the fossil fuel era, provoking concerns regarding how plant species are and will continue to respond to new climatic conditions 1. Studies regarding how trees have responded to historic changes in temperature and precipitation are particularly critical for predicting how species may migrate and adapt under future climate change scenarios. This study will evaluate ring width indices for Pinus contorta spp. latifolia (lodgepole pine) throughout its range in British Columbia in order to examine correlations between growth and climate trends over the last three decades. Sampling will take place in 35 year-old provenance trials, allowing for genetic comparisons of growth responses for six populations planted across an environmental gradient over time 2. Methods Field sites Lodgepole pine common gardens across the species range in BC and the southern Yukon Expected results Climate variable radial growth correlations Positive correlation with precipitation of the current and previous year; Positive correlation with spring and summer temperature except when threshold temperatures exceeded; Negative correlation with summer heat:moisture index when threshold index exceeded. Climate-genotype growth interactions Greater absolute radial growth in warmer climates than colder climates for all populations at all sites; Annual radial growth increasing temporally for all populations at all sites; Population with climate index most similar to trial site will have greatest percent increase in radial growth over time; Greater variation in annual radial growth increment in populations from species range margins, regardless of where planted. References 1.Davis, M.B. and Shaw, R.G. (2001) Science 292: Rehfeldt, G.E. et al. (1999) Ecol. Monogr. 69: Stokes, M.A. and Smiley, T.L. (1968) U. Chicago Press This project was funded by the BC Forestry Investment Account through the Forest Genetics Council of BC. Acknowledgments Objectives 1. Assess genotype-environment interactions in lodgepole pine populations planted across an environmental gradient by examining correlations between radial growth and climate variables over the last 30 years; 2. Assess the potential for expansion/contraction of the lodgepole pine species range based on observed deviations of growth from normalized radial increments. Albreda: 52 NTakhini: 60 NManning: 49 NChampion: 49N Sampling methodology take radius cores at breast height: - 12 trees per provenance - 7 provenances per trial site (5 standard, 1 standard B+, 1 local) - 15 trial sites TOTAL: 1,260 tree cores Analyses mount, sand and crossdate cores 3 perform analyses comparing: 1. annual growth to climate variables; 2. within and between-population growth variation relative to climate and location; 3. growth rates at and in populations from the species range margins. Potential field sites: Selected to cover as wide a climatic and latitudinal range as possible. Mapped by mean annual temperature (-18 to 12° C). Site Mean stem area increment (cm 2 ) Lodgepole pine in a common garden: population growth differences 1: ABCDE 2: ABCDE 3: ABCDE 4: ABCDE 5: ABCDE Genetic growth correlations: Hypothetical results for five fictitious populations (A - E) reciprocally planted in five fictitious sites (1 – 5) across a north-south climatic gradient (see inset map). Arrows represent expected growth trends over recent decades: pink indicates populations expected to have the greatest percent increase in radial growth; green indicates populations expected to have the most variation in growth.