White spruce (Picea glauca) is a coniferous tree and part of the greater Pine family (Pinaceae). It is native to northern temperate and boreal forests in North America, which are characterized by cool summers and long, cold winters (Hogg et al. 2017). The species has adapted to extremely cold temperatures in Northern Canada and Alaska, yet spreads as far south as Wyoming US (see map 1). White spruce is important both ecologically and commercially in western Canada where it commonly grows as a late-successional species in mixed wood stands with aspen (Hogg et al. 2017). Harvested White spruce is used for construction, paper production and Christmas trees.
By the end of the century, the CCCR (Canada's Changing Climate Report) anticipates an average temperature rise of 1.9 to 2°C throughout Alberta. Furthermore, some research shows that Alberta had already become significantly warmer and dryer over the past 112 years and these conditions are projected to continuously increase in all seasons by up to 8.6°C (Jiang et al. 2017) (see Figure 1). This rapid change in habitat conditions will likely cause reduced tree productivity and potentially even widespread tree mortality (Benomar et al. 2018; Sang et al. 2019).
In recent years several studies have pointed out White spruce vulnerability to the changing conditions induced by climate change; suggesting that these forests are at risk if the trend towards more frequent, severe drought in Alberta continues (Chen et al. 2017; Hogg et al. 2017; Benomar et al. 2018; Sang et al. 2019).
Results of previous Whites spruce productivity studies from western Canada have revealed a relatively large decline in biomass increment of white spruce and other late-successional conifers, along with a trend towards decreased abundance relative to other tree species (Hogg et al., 2017) (See figure 2). |
A possible solution to the maladaptation of white spruce to the changing climate is assisted migration, which means moving seed sources from areas with climate variables that match the forecasted new conditions at a desired reforestation or forest management site.
My objective in this project is to determine the relationship between tree productivity (measured by tree height) and different climate variables, thus making it easier to select seed sources for future reforestation and reclamation endeavors. My hypothesis is that temperature and precipitation will be most influential to white spruce productivity. I expect that there will be an optimal range where productivity is higher for both the temperature and precipitation variables, and a parabolic decline on both tails. Understanding the roles different factors play in White spruce productivity will allow for a better selection of seed sources. For example, if my results show that precipitation influences productivity to a larger degree than temperature, an appropriate donor site will be one that closely resembles projected moisture conditions in the receiving site, while the temperature will be of lesser concern. Such an understanding will hopefully promote better consequences of reforestation and forest management efforts.
My objective in this project is to determine the relationship between tree productivity (measured by tree height) and different climate variables, thus making it easier to select seed sources for future reforestation and reclamation endeavors. My hypothesis is that temperature and precipitation will be most influential to white spruce productivity. I expect that there will be an optimal range where productivity is higher for both the temperature and precipitation variables, and a parabolic decline on both tails. Understanding the roles different factors play in White spruce productivity will allow for a better selection of seed sources. For example, if my results show that precipitation influences productivity to a larger degree than temperature, an appropriate donor site will be one that closely resembles projected moisture conditions in the receiving site, while the temperature will be of lesser concern. Such an understanding will hopefully promote better consequences of reforestation and forest management efforts.