Arctic plant responses to changing abiotic factors in northern Alaska

Abstract

PREMISE OF THE STUDY: Understanding the relationship between plants and changing abiotic factors is necessary to document and anticipate the impacts of climate change. M ETHODS: We used data from long-term research sites at Barrow and Atqasuk, Alaska, to investigate trends in abiotic factors (snow melt and freeze-up dates, air and soil temperature, thaw depth, and soil moisture) and their relationships with plant traits (infl orescence height, leaf length, reproductive effort, and reproductive phenology) over time. K EY RESULTS: Several abiotic factors, including increasing air and soil temperatures, earlier snowmelt, delayed freeze-up, drier soils, and increasing thaw depths, showed nonsignifi cant tendencies over time that were consistent with the regional warming pattern observed in the Barrow area. Over the same period, plants showed consistent, although typically nonsignifi cant tendencies toward increasing infl orescence heights and reproductive eff orts. Air and soil temperatures, measured as degree days, were consistently correlated with plant growth and reproductive eff ort. Reproductive eff ort was best predicted using abiotic conditions from the previous year. We also found that varying the base temperature used to calculate degree days changed the number of signifi cant relationships between temperature and the trait: in general, reproductive phenologies in colder sites were better predicted using lower base temperatures, but the opposite held for those in warmer sites. CONCLUSIONS: Plant response to changing abiotic factors is complex and varies by species, site, and trait; however, for six plant species, we have strong evidence that climate change will cause signifi cant shifts in their growth and reproductive eff ort as the region continues to warm.