Spatial variation in blueberry (Vaccinium uliginosum) and lingonberry (Vaccinium vitis-idaea) fruit production in Interior Alaska

Abstract

There are over 50 species of plants in Alaska that produce fleshy fruits (hereafter: "berries"), of which people consume 25. Berries are a key cultural and nutritional resource in rural Alaska and an important source of calories for a range of animals including bears (Ursus spp.), foxes (Vulpes vulpes), geese (e.g., Branta hutchinsii), and voles (e.g., Myodes rutilus). Berry production, from bud development to ripe fruit, takes at least 15 months and may be affected by factors even a year or two before that. Many studies in the circumpolar North focus on these interannual effects on fruit production but few assess how local variation within a forested region may affect berry numbers. Changes in the frequency and severity of wildfires in the boreal forest has affected soil conditions and plant community structure, which may alter the range of circumstances a species must respond to, influencing overall fruit production at a site. I studied how fruit production in Vaccinium uliginosum (blueberry) and V. vitis-idaea (lingonberry), responded to factors such as pollen load, floral resources, canopy cover, and soil conditions within forest sites of Interior Alaska. I found two distinct habitat types in the Interior Alaskan forest, upland and lowland, which differed by elevation, soil moisture (lower in upland sites), and active layer (deeper in upland sites). We found lingonberry was more pollen limited than blueberry, and plants in lowland sites were more pollen limited while plants in upland sites were more resource limited. Additionally, canopy cover had a significant negative effect on a ramet's investment in flowers, berries, and leaves, versus structural growth, in upland sites but little effect in lowland sites. I was able to explain more of the variation in berry production and resource allocation in upland sites than lowland sites. Pollen and resource limitation differed between the two species and between uplands and lowlands suggesting Vaccinium berry production and resource allocation is partially defined by spatial variability of the landscape.