IMPACT OF CLIMATE-CHANGE FACTORS ON THE CLONAL SEDGE CARER BIGELOWII - IMPLICATIONS FOR POPULATION-GROWTH AND VEGETATIVE SPREAD

Hypothesized life-cycle responses to climate change for the arctic, cl onal perennial Carer bigelowii are constructed using a range of earlie r observations and experiments together with new information from moni toring and an environmental perturbation study. These data suggest, th at under current climate change scenarios, increases in CO2, temperatu re and nutrient availability would promote growth in a qualitatively s imilar way. The evidence suggests that both tiller size and daughter t iller production will increase, and be shifted towards production of p halanx tillers which have a greater propensity for flowering. Furtherm ore, age at tillering as well as tiller life span may decrease, wherea s survival of younger age classes might be higher. Mathematical models using experimental data incorporating these hypotheses were used to a ) integrate the various responses and to calculate the order of magnit ude of changes in population growth rate (lambda), and b) to explore t he implications of responses in individual demographic parameters for population growth rate. The models suggest that population growth rate following climate change might increase significantly, but not unreal istically so, with the younger, larger, guerilla tillers being the mos t important tiller categories contributing to lambda. The rate of vege tative spread is calculated to more than double, while cyclical trends in flowering and population growth are predicted to decrease substant ially.