Bees like trees: past and future trends in forest composition and implications for pollinators

Background/Question/Methods

Wild bee communities provide pollination for crops and non-agricultural plants and require adequate nutrition for reproduction, learning, and memory. Forests, specifically forest trees, have only recently been recognized as an important source of early-season pollen and nectar. To our knowledge, there are no studies quantifying trends in forest flowering in the Northeast USA, especially considering landscape and regional scales. To quantify spatio-temporal patterns in forest flowers, we coupled empirical estimates of bloom density and flower size with forest composition data from the United States Forest Service, Forest Inventory and Analysis (USFS FIA) program.

Results/Conclusions

We documented spatial variation in abundance of flowers and diversity of flowering trees in forests (2005-2019) and found relatively little change in the total area of flowers from forest trees in the Northeast. Based on USFS projections of future suitable habitat for forest trees, we estimated forest flowers circa 2100 and identified tree species that are likely winners (Quercus sp.) and losers (Betula sp.) of future climate conditions. We highlight implications of climate change for forest tree-pollinator interactions and showcase the utility of the extensive FIA monitoring program to map forest flowers for bees and inform decisions about conservation, restoration, and management.