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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]

A field study was conducted to assess the long-term effects of growing trees on ecosystem and soil carbon (C) pools in a pasture landscape situated in the Boreal Transition ecozone of Saskatchewan that is characterized by Black Chernozemic soils. Tree species consisted of white spruce (Picea glauca (Moench) Voss) and Siberian larch (Larix sibirica Lebed.) and had been growing for 50 years before soils were sampled and analyzed for C and N concentrations, particle size distribution, and bulk density. Above- and belowground (roots) biomass were also determined respectively by allometry and soil washing. Ecosystem C gains in the forested plots were evident when compared to pasture plots. Most of this gain was attributed to the standing biomass and to lesser extent to forest floor development. However, C pools in the Black Chernozemic A horizons were decreased under trees and were apparently redistributed to the B horizons. Multiple linear models developed to explain C levels in the mineral soil at different depths indicated a significant shift from soil C being driven by root litter quality in the Ah horizons to being driven by root litter quantity in the B horizons. The model of C redistribution was consistent with other studies and is closely tied to root production and quality. Whether a new steady-state C level in the Chernozemic A horizons was reached still needs to be elucidated, but previous research in the region suggest that tree invasion on well-drained Black Chernozems could lead to “dechernozemization” through acidification and C loss. [Copyright &y& Elsevier]

Discusses the treatment of a clear-cut aspen stand, near Prince Albert, Saskatchewan, to encourage the establishment of mixed aspen-white spruce forest. Site preparation methods used, such as the use of a v-blade, disc trencher and Bracke mounder, as well as a drum chopper in combination with the disc trencher and Bracke; Production of moderate height and biomass increases and low mortality rates; Reduction of competing aspen and shrub growth.

The influence of dry climates on white spruce (Picea glauca (Moench)Voss)) regeneration was examined by conducting surveys of seedlings and small trees that had regenerated naturally at 100 farm shelterbelts and plantations in southern Saskatchewan, Canada. The sites surveyed were located along a climate moisture gradient extending from the relatively moist boreal forest, across the aspen parkland, to the semi-arid prairie grasslands. Natural regeneration was greatest at sitesin the boreal forest and northern aspen parkland, decreased in the southern aspen parkland, and was negligible in the grassland zone. Furthermore, the few seedlings found in the drier zones were usually in poor condition. Similar results were obtained for the introduced Colorado spruce (Picea pungens Engelm.) and Scots pine (Pinus sylvestris L.). It is concluded that the present climate of the southern parkland and grassland is too dry to permit natural regeneration of white spruce and other conifers. If increases in atmospheric CO2 levels lead to a drier future climate in the southern boreal forest ofwestern Canada, the ability of conifers to regenerate naturally may be significantly reduced. [ABSTRACT FROM AUTHOR]