COS 58-3 - Are pollinator communities limited by landscape-scale floral resources?

Background/Question/Methods

Though multiple studies indicate that pollinators are highly influenced by their surrounding landscape, we lack a mechanistic understanding of what specific components of this landscape are most limiting to populations. We quantified floral resource availability at landscape scales to relate to the abundance, diversity, and performance of pollinators in New York State, USA. We modeled floral resource availability through detailed surveys of the plant communities in the major habitat types (N=144 plots in 22 habitat types) in Central New York State. Using plant survey data along with bloom time and flower size measurements, we calculated daily habitat-level floral area as a proxy for floral resources through time. We created a region-wide habitat map consisting of the sampled habitat types and their corresponding daily floral area throughout the growing season. Using this resource map, we tested the hypothesis that floral resource gaps would be an important constraint on pollinator communities. To do so, we related pollinator community data collected from the same region to the following resource metrics: total floral area, maximum floral area, variability in floral area, and minimum floral area.

Results/Conclusions

Habitats varied considerably in the amount of resources each provided, with forests providing the most resources, though heavily concentrated in the spring. Wetland habitats and agricultural or early successional habitats (e.g. old fields) provided the majority of their resources in the mid to late stages of the growing season. Gaps in floral resources occurred between the early-season blooms and the mid- to late-season blooms. These resource gaps, along with variability in resources, negatively impacted wild bee populations. Our findings suggest that conservation efforts should address filling resource gaps with appropriate habitat that blooms heavily during the gap periods, either through habitat restoration or refraining from mowing at critical periods (if managed).