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• Drought response of three disparate shelterbelt species is explored. • Severe and extreme 3-month droughts most greatly affect tree. • Scots pine and white spruce recover more quickly than green ash. Across western Canada, more frequent and severe droughts are expected to occur as a result of climate change. Forests are particularly vulnerable to drought as it often results in mortality events even years following a moisture deficit. Similar events have been observed in Saskatchewan shelterbelts, where many species are planted far outside their native range and are likely more vulnerable to environmental changes. Understanding how common shelterbelt species respond to drought will help landowners make better management decisions under a changing climate. This study looks at how three common shelterbelt species (green ash, Scots pine and white spruce) respond to different drought characteristics (severity, timing, and length) for up to five years following a moisture deficit using superposed epoch analysis. We identified that severe and extreme 3-month droughts greatly impact all three species. However, Scots pine and white spruce tend to recover more rapidly than green ash. Green ash is typically considered one of the most drought tolerant shelterbelt species, but its long recovery times suggest that this may be false. Scots pine was impacted by late summer droughts and white spruce was impacted by June droughts. Both Scots pine and white spruce also saw compensatory growth after their recovery period. This research augments our understanding of how drought characteristics impact three common shelterbelt species in Saskatchewan and how they are likely to recover under more frequent and severe drought events given projected climate change. [ABSTRACT FROM AUTHOR]

Many studies have already addressed the existence of unstable and nonlinear relationships between radial growth of white spruce ( Picea glauca ) and climate variables in boreal forests along the high latitudes (>60° N). However, along the mid-latitudes, the climate-growth relationship is still poorly understood. In this study, we used a network of ring-width chronologies from 40 white spruce sites along a wide latitudinal gradients from 52° N to 58° N in Alberta, Canada and attempted to understand the complicated response of tree growth to climatic variables and to identify the main limiting factor for the radial growth of white spruce. We combined the empirical linear statistics with the process-based Vaganov-Shashkin Lite (VS-Lite) model requiring only latitude, monthly mean temperature, and monthly total precipitation information together to better clarify growth-climate relationship. The linear statistical methods indicated that the previous summer temperature imposed a strong negative impact on the radial growth of white spruce while the precipitation and climate moisture index in prior and current summer both had significant positive effects on the radial growth. Similarly, the VS-Lite model showed that the radial growth of white spruce was limited by soil moisture. This suggests that temperature-induced drought is the main limiting factor for the radial growth of white spruce. Furthermore, climate-growth relationship varied along different elevations, latitudes, and growing degree days (GDD >5 °C). The radial growth of white spruce in northern stands was often more strongly limited by temperature-induced drought due to the higher temperature and lower precipitation. As the global climate change is in progress, we suggest that more large-scale and continuous investigations are needed to address the spatial variation in growth-climate relationship due to the temperature-induced drought. [ABSTRACT FROM AUTHOR]