Effects of Biochar on Pollinator Plantings and Foraging Bees in a Southeastern Soil

Abstract

Bees are a diverse clade of insects pivotal to pollination in anthropogenic and natural systems. Yet, this diversity is threatened by human-driven changes in the environment. The establishment of pollinator habitat plantings has, and remains, a valuable tool for bee conservation. Their success, however, depends on the provision of diverse and abundant forage able to provide pollen and nectar resources for a diversity of species. Investigating methods to improve pollinator habitat establishment remains a top priority in the conservation of a declining melittofauna. In this thesis, I tested the effects of biochar – a carbon-based soil amendment – derived from pine (Pinus spp.) on pollinator habitat plantings in Auburn, AL during the 2023 growing season. In chapter 2, I compared the effects of biochar on the soils, as well as the community characteristics of floral and foraging bee assemblages, between biochar-amended and control subplots. In chapter 3, I compared the photosynthetic activity (NDVI) and plant height of the overall vegetation between these same subplots. I found that biochar amendment resulted in significant increases in the density of three wildflower species and decreases in the densities of three bee species. Community composition and diversity were unaffected, as were photosynthetic activity and plant height. These results suggest that a pine-based biochar applied at 10 mt ha-1 may not have strong effects the first year after application in a sandy, southeastern soil. Additionally, wildflower and bee species may not respond the same way to soil manipulation, implying that reliance on wildflowers as sole indicators of a planting’s value to foraging bees may not be appropriate. However, the effects of biochar should be monitored long-term to determine the extent of biochar’s impact on pollinator habitat plantings.