Collaborative Research: Plant phenology, local adaptation, and growing season length in the changing Arctic tundra

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In the Arctic, plants begin their growth after winter snow melts in June. They stop growing when cold temperatures return in August. The growing season in the Arctic is shorter further north and longer towards the south. This causes the timing of their growth to vary between different populations of common plants. Because of climate change, the Arctic is getting warmer faster than areas that are further south, and the growing season is getting longer. Some plants may not adjust to the longer growing season because of their genes. In contrast, others may have genes that permit them to change. We find both kinds in the Arctic. This research will examine how light, temperature, and genetics work together to determine how arctic plants respond to changes in the growing season. For some plants, we will adjust the amount of light they receive to see how the plants respond. We will study if the plants have genes that allow them to stay active if the growing season changes. This approach will help to understand whether the plants will grow in a future warmer Arctic. To help the scientists working in Alaska, high school students in Pennsylvania will grow arctic plants in a laboratory to see how they respond to changes in light. College students from the University of Texas at El Paso will help with fieldwork in Alaska.Plant phenology, or the timing of leaf initiation, leaf death, and flowering, is one trait most affected by climate change. In the Arctic, changes in plant phenology can alter how ecosystems function at multiple levels. Previous research by our group identified a significant difference in growing season length between northern and southern populations of tussock cottongrass. This finding suggests that the phenology of this species is under genetic constraint. The present project will investigate the effect of local adaptation on the phenology of tussock cottongrass and two of its competitors, the dwarf birch and tealeaf willow. The hypothesis is that temperature, light, and genetics, in different combinations, are responsible for differences in phenology in the Arctic. The strength of these controls will vary between populations that are found in different environments. Field and growth chamber experiments will determine the role of temperature, light, and genetics on plant phenology. We will monitor plants at the leaf and ecosystem scales to understand how phenology and growing season length affect plant function and ecosystem responses. A combination of methods will provide a unified approach to plant response to climate change in the Arctic. This project will have broader impacts on arctic science by building on a strong tradition that involves undergraduates in arctic field research. The project will recruit assistants from a small university with many first-generation students and from a leading Hispanic Serving Institution. It will also involve high school students from Wilkes-Barre in laboratory studies of phenology.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.