The effects of climate change on the radial growth of four shelterbelt species across the Brown, Dark Brown, and Black soil zones of Saskatchewan

Abstract

Mitigating climate change has become a common theme in numerous research projects in Saskatchewan, and shelterbelts are highlighted as one of the potential ways to help mitigate climate change by sequestering carbon. The issue with shelterbelts, is that it is unknown how shelterbelts will grow under future climate change conditions in the already harsh climate of the Saskatchewan prairies. The purpose of this study was to predict the radial growth of the shelterbelt species green ash (Fraxinus pennsylvanica), hybrid poplar (Populus hybrids), Scots pine (Pinus sylvestris), and white spruce (Picea glauca) across the Brown, Dark Brown, and Black soil zones of Saskatchewan. Tree cores were collected at 68 sites for this study, and for each site a master chronology of tree rings was constructed. The master chronologies and past climate records were used in a linear regression model to determine the past responses of the tree species at each site to climate. These responses along with future climate data from climate models were used to predict the future growth of each species at each site. Maps summarizing the predicted growth of each species were created to make the information easier to interpret. Green ash growth is predicted to increase across most of south-central Saskatchewan up to the year 2100, excluding areas in the more westerly areas of the province. The reason for this increase is mainly attributed to green ash’s positive relationship to spring and June precipitation, which is predicted to increase in the future. Hybrid poplar radial growth is predicted to slightly decrease in the future. This decrease is small and will be slow to develop because the decreases in hybrid poplar radial growth that are caused by rising summer temperatures are counteracted by predicted increases in autumn precipitation which is positively related to hybrid poplar growth the following year. Scots pine’s driver of growth is spring and summer (mainly June) precipitation which is predicted to increase under climate models. For this reason, Scots pine growth is predicted to increase in the westerly areas of southern Saskatchewan. Scots pine growth is also predicted to increase in the north, which is attributed to the positive impact that spring temperature has on Scots pine growth. White spruce radial growth is predicted to decrease across the Brown, Dark Brown, and Black soil zones of Saskatchewan because rising future temperatures will likely cause temperature-induced drought in white spruce across the southern half of Saskatchewan. Predicting the growth of these common shelterbelt species will help

landowners choose a shelterbelt species that will grow well in their area of the province under climate change conditions and may help policy makers to make informed decisions about using shelterbelts for potential carbon offset credits.