Variations in growth, survival and carbon isotope composition (δ13C) among Pinus pinaster populations of different geographic origins

To evaluate differences in growth and adaptability of maritime pine (Pinus pinaster Ait.), we studied growth, polycyclism, needle tissue carbon isotope composition (δ13C) as an estimate of water-use efficiency (WUE) and survival of seven populations at 10 years of age growing in a performance trial at a provenance test site in Escaroupim, Portugal. Six populations were from relatively high rainfall sites in Portugal and southwestern France (Atlantic group), and one population was from a more arid Mediterranean site in Spain. There were significant differences between some populations in total height, diameter at breast height, δ13C of bulk needle tissue, polycyclism and survival. A population from central Portugal (Leiria, on the Atlantic coast) was the tallest and had the lowest δ13C. Overall, the variation in δ13C was better explained by the mean minimum temperatures of the coldest month than by annual precipitation at the place of origin. Analyses of the relationships between δ13C and growth or survival revealed a distinct pattern for the Mediterranean population, with low δ13C (and WUE) associated with the lowest growth potential and reduced survival. There were significant negative correlations between δ13C and height or survival in the Atlantic group. Variation in polycyclism was correlated with annual precipitation at the place of origin. Some Atlantic populations maintained a high growth potential while experiencing moderate water stress. A detailed knowledge of the relationships between growth, survival and δ 13C in contrasting environments will enhance our ability to select populations for forestry or conservation. © 2008 Heron Publishing.