| Summary: | Predictions that climate warming will enhance plant sexual reproduction in the High
Arctic were examined using a field experiment at a polar oasis and a polar semi-desert
site in the eastern Canadian High Arctic. Small open top chambers (OTCs), which
simulated climate warming, were established in plant communities along a soil moisture
gradient in 1992. Over two growing seasons, fresh and over-wintered seeds across a
range of species were collected from aerial seed banks exposed to experimental warming
and ambient conditions. Seeds were weighed and germinated to measure changes in
reproductive effort and success in response to experimental warming. OTCs increased
within-plot growing season air temperatures by 1 - 2°C, which is within range of general
circulation model (GCM) predictions for climate warming in the Arctic. Reproductive
effort and success of fresh seeds were enhanced by warming in most species, depending
on initial site conditions. Enhanced reproductive effort and success may be attributed to
warming conditions, which advanced dates of snowmelt and extended the growing
season. Similar effects on over-wintered seeds were likely, but seed dispersal prior to
over-wintered seed harvests confounded these results. Inter-annual variability in
reproductive success appeared to be diminished by experimental warming. Further
testing will verify if this result is an indicator of long-term (> 10 y) warming effects.
Results of this study confirm predictions that long-term warming will enhance sexual
reproduction in high arctic plants. These changes will have implications for plant
demographics at the community-level and the rate and extent of bare-ground
colonization, particularly if rates of seedling establishment also increase. === Arts, Faculty of === Geography, Department of === Graduate
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