Long-term Phenological Changes in Tundra Plants in Response to Experimental Warming Using the International Tundra Experiment (ITEX) Network
Arctic regions are predicted to undergo strong warming in coming decades, and they have already undergone measurable warming within recent decades. A coordinated international experiment on the effects of warming on the phenology and growth of individual tundra species and on plant communities, the International Tundra Experiment (ITEX), started in 1990 to directly measure the ways in which tundra plants and communities respond to consistent, low-level increases in temperature across the tundra biome. Specifically, previous meta-analyses utilizing the ITEX program to evaluate changes of the phenology and growth data from throughout the tundra biome resulted in a synthesis paper limited to the first 4 years of warming in the history of the ITEX. We will present results of a second meta-analysis of the phenological responses of plants across the tundra biome. The primary objective of this synthesis paper is to evaluate changes in plant phenology across the tundra biome over the past 10-15 years in response to experimental warming. We compared our comprehensive historical data sets on timing of green up, flowering, senescence and seed maturation, with new phenological measurements to evaluate temporal changes in plant phenology in ITEX open-top-chamber (OTC) warmed and control plots. Our preliminary results suggest that warming effects vary across and within tundra types, across plant communities and plant functional groups, in some cases, suggesting a reversal of the effects of the experimental OTCs toward effect sizes more typical of the early years of treatment in the high arctic. This project meets the goals of the IPY program as an International Observing Network with strong research, international networking and outreach components studying effects of climate change and experimental warming on ecosystems across the tundra biome.
