UBC Theses and Dissertations
Radial growth responses in Dryas integrifolia to ambient and experimental warming in the high Arctic Grishaber, Emily
The rate of environmental change in the Arctic is greater than in any other global biome. Dendrochronological methods have been used in arctic ecosystems to investigate growth changes experienced by woody plants as a result of climate change. Recent and projected future climate warming in the Arctic is expected to increase plant growth potential as arctic ecosystems are heat-limited environments. Recent studies suggest that warmer local temperatures are linked to increases in shrub abundance and growth across the tundra, and that these responses are highly specific to local site conditions and species investigated. Here, we investigated ring-widths from stem/root collars of Dryas integrifolia, a common dwarf evergreen species, collected from three subsites along a moisture gradient at a High Arctic field site, Alexandra Fiord, Ellesmere Island, NU, to determine growth relationships with local environmental variables. We used a passive warming treatment to investigate effects of a 1-3⁰ C increase in growing season temperature over 20 years on the growth of Dryas integrifolia. We determined that temperature was a significant driver of radial growth, demonstrating larger ring width sizes of shrubs grown in the experimental warming treatment compared to plants grown in the control treatment. However, temperature did not appear to be directly correlated to ring width size. Soil moisture was significantly correlated to ring width of plants grown in warmed plots from two of the three investigated subsites at Alexandra Fiord. No other measured environmental variable showed a significant relationship with ring width size. The results from this study suggest that D. integrifolia growth responds to temperature and soil moisture levels; however, the direction and degree of response is highly dependent on local site conditions. These results are consistent with others found from Arctic plant studies, which generally conclude that the effect of environmental change on plant species and communities is variable in time and space. Shrubs are anticipated to proliferate throughout Arctic tundra ecosystems with future warming, and understanding the direct effects of temperature on growth will provide insight as to how we may expect these ecosystems to shift with climate change.
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