COS 55-6 - No more winter fruits? Changes in fruit retention and quality for four "berry" species across Alaska under climate change

Abstract: Plants that retain their fruits into fall and winter are critical to wildlife and people across the far north. Changes in the start of flowering (which drives the time of fruit ripening), temperature and precipitation, and time of season-long snow onset under climate change are expected to affect the quantity and quality of fruits available to animals during late fall and winter. We predicted changes in the availability and quality of fruits of four "berry" species of high importance to animals and people (Rosa acicularis, Vaccinium vitis-idaea, Viburnum edule, and Empetrum nigrum) across six ecoregions in Alaska by combining an extensive dataset collected by the Winterberry community science network ( >1500 people, primarily youth groups in rural communities) with predicted changes in temperature and precipitation over the next 75 years. Rate of fruit loss was unaffected by temperature or precipitation during the previous week, month, or summer, but the proportion of fruits that were healthy (not rotten or dried out) was most commonly explained by temperature during the previous month (with colder temperatures associated with a higher % healthy fruits) and sometimes summer temperatures (warmer temperatures were associated with higher % healthy fruits). Changes in start date of fruit production had the strongest impact on fruit production and loss, followed by changes in summer and fall temperatures. For example, R. acicularis in interior boreal forest had a reduction in fruit available at time of snow onset from 24% under current conditions to 2% by 2060-2069 and 0% by 2090-2099, while the date on which 50% of fruits were healthy shifted from 27 September to 10 September and 5 September respectively. Differences in nutrient content between healthy and unhealthy fruits further reduced nutrient availability in early fall, especially for K, Mn, and water content. These results suggest that winter fruit availability will be severely reduced or entirely absent by the end of the century.