Spatial and temporal variability in dendroclimatic growth response of red pine (Pinus resinosa Ait.) to climate in northern Ontario, Canada

Abstract Growth–climate relationships of trees are species-specific and can vary over space and time. Here, we study red pine ( Pinus resinosa Ait.) by analyzing tree-ring width data from 37 sites across northern Ontario, Canada for the period 1901–2010. We performed response function and moving response function analyses using seasonal data of three climatic variables: precipitation, minimum temperature and maximum temperature. Our analyses show considerable spatial and temporal variability in red pine growth response to climate during the 20th century. In general, red pine growth responses to climate were more significant in northwestern Ontario than in northeastern Ontario. Overall, precipitation was the most significant predictor of red pine growth, with seasonal variations across sites. Unlike many other studies, we did not find any significant growth response to current year summer temperature. Instead, at many sites in northwestern Ontario, red pine had a significant negative growth response to prior summer temperatures. The results of canonical correspondence analysis show that red pine growth response to climate follows a longitudinal gradient. Temporal stability analyses revealed that growth–climate response of red pine at any site was not stable during the 20th century. We observed a general shift from significant growth response to seasonal temperature during the first half of the 20th century to significant growth response to seasonal (except for spring) precipitation during recent decades. The spatial and temporal variability of red pine growth response to climate detected in our study should be considered in future plans for forest management of this species and can also be used for better understanding forest ecological dynamics at the regional scale for conservation purposes.