Patterns of pollen and resource limitation of fruit production in Vaccinium uliginosum and V. vitis-idaea in Interior Alaska

Abstract

Many recent studies assessing fruit productivity of plants in the boreal forest focus on interannual variability across a forested region, rather than on environmental variability within the forest. Frequency and severity of wildfires in the boreal forest affect soil moisture, canopy, and community structure at the landscape level, all of which may influence overall fruit production at a site directly or indirectly. We evaluated how fruit production in two boreal shrubs, Vaccinium uliginosum (blueberry) and V. vitis-idaea (lingonberry), was explained by factors associated with resource availability (such as canopy cover and soil conditions) and pollen limitation (such as floral resources for pollinators and pollen deposition) across boreal forest sites of Interior Alaska in 2017. We classified our study sites into upland and lowland sites, which differed in elevation, soil moisture, and active layer. We found that resource and pollen limitation differed between the two species and between uplands and lowlands. Lingonberry was more pollen limited than blueberry, and plants in lowland sites were more pollen limited relative to other sites while plants in upland sites were relatively more resource limited. Additionally, canopy cover had a significant negative effect in upland sites on a ramet's investment in reproductive tissues and leaves versus structural growth, but little effect in lowland sites. These results point to importance of including pollinator service as well as resource availability in predictions for changes in berry abundance.

Preforming floral primordia converge on a narrow range of stages at dormancy despite multiple effects of temperature on development

“…Only some shoots became reproductive, and whether the shoots had formed an inflorescence or remained vegetative could not be determined at collection until late in the growing season (see Table S2 for number of reproductive shoots and primordia at each collection date). Vaccinium vitis‐idaea is less likely to flower when canopy cover is high (Parkinson & Mulder, 2020), and this is reflected in fewer dates on which reproductive shoots were collected in the shadiest sites (Table S1). Because in early June we could not distinguish between shoots without flower primordia that would not become reproductive and shoots with no primordia that would subsequently transition to flower initiation, we present values for June flowering shoots in figures but do not include this collection in the quantitative analyses of development.…”

Parameterization and Calibration of Wild Blueberry Machine Learning Models to Predict Fruit-Set in the Northeast China Bog Blueberry Agroecosystem

“…Based upon wild blueberry, some of the mechanisms of decreased fruit set due to climate warming and increased precipitation are: reduced activity of bees during rainy days, reduction of the longevity of stigma viability during warm springs, faster rate of progression through the bloom period by the flowering clones (genetically unique individual plants), asynchrony between the emergence of wild bees and the early blooming clones, and increased blossom loss due to infection by Monilinia vaccinii-corymbosi (Reade) (the causal fungal organism of mummy berry disease) [15,26,68]. Parkinson and Mulder [2] also support our hypothesis that bog blueberry fruit set will be affected in a similar way that wild blueberry fruit set is by warming. In Alaska, USA, they found that bog blueberry exhibited a decline in fruit set in warmer lowland sites relative to cooler upland sites.…”

“…Bog blueberry (Vaccinium uliginosum L.), is a Eurasian and North American flowering plant species in the genus Vaccinium within the heath family [1,2]. The commercial value of bog blueberries comes from their antioxidant content, which is the highest of 40 common fruits and vegetables [3].…”