Resource Allocation and Allometry of Plant Growth in the Arctic: Key Constraints on Change and Predictability of the Arctic System

Marine Biological Laboratory, Woods Hole MA

Investigators

Abstract

The proposed research will contribute to the main themes of the Arctic System Science program by improving our understanding of the broad patterns of vegetation change and vegetation function across the Arctic. The underlying hypothesis is that evolutionary adaptation to the arctic environment places constraints on the patterns of growth of arctic plants (i.e., on their resource allocation patterns and allometry of growth), and that these adaptations in turn play an important role in regulating change and resilience in arctic vegetation and its feedbacks to the Arctic System. The proposed research is designed essentially as a search for the general characteristics of plant growth, resource allocation, and allometry that can be used to develop large-scale, long-term predictions of vegetation properties and of the role of arctic vegetation in the Arctic System. By comparing a wide range of vegetation types in widely-separated sites, the research will also help to identify the relative vulnerability of different vegetation types, plant functional types, and species to climate change and other forms of disturbance. The research sites include Toolik Lake, Alaska; Abisko, Sweden; Ny Alesund, Svalbard; and Zackenberg, Greenland. The plant variables to be evaluated--primary production, C fluxes, N turnover, NDVI, and canopy structure--are all key components of the feedbacks and interactions between the terrestrial landscape and the cycles of energy, water, and elements in the Arctic System. Field research at each site will include quadrat harvests for analysis of production-biomass relationships, biomass allocation patterns, N turnover and use, and canopy leaf area-leaf N interactions. Additional sampling will relate these variables to CO2 fluxes, stem density and branching patterns, and NDVI. Winter visits will determine effects of stem and canopy structure on snow and winter microclimate. In addition to empirical analysis of results, one product of the research will be a data base for modeling and extrapolation of vegetation properties and processes across the Arctic region. Long running collaborations with established modeling groups will continue. The major issues of broader interest here are (1) the scaling of ecological understanding from single sites and species to larger, regional environmental systems, (2) the effects of individual species or plant "functional types" on overall ecosystem and landscape-level processes, and (3) the meaning and measurement of resistance, resilience, and stability of ecosystems and landscapes in a world of constant change. Resolution of these issues is key to development of sound policies on conservation and management of ecosystems and landscapes everywhere. The proposed research will also make several contributions to education of future professionals and of the general public, by continuing our long-term involvement with training of undergraduate REU students, postdoctoral fellows, technicians, and science journalists.