Switchgrass (Panicum virgatum) Intercropping within Managed Loblolly Pine (Pinus taeda) Does Not Affect Wild Bee Communities.

Joshua Campbell,James Martin,Darren Miller

doi:10.3390/insects7040062

Joshua Campbell, James Martin + Show 1 more

Open Access

https://doi.org/10.3390/insects7040062

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Abstract

Intensively-managed pine (Pinus spp.) have been shown to support diverse vertebrate communities, but their ability to support invertebrate communities, such as wild bees, has not been well-studied. Recently, researchers have examined intercropping switchgrass (Panicum virgatum), a native perennial, within intensively managed loblolly pine (P. taeda) plantations as a potential source for cellulosic biofuels. To better understand potential effects of intercropping on bee communities, we investigated visitation of bees within three replicates of four treatments of loblolly pine in Mississippi, U.S.A.: 3–4 year old pine plantations and 9–10 year old pine plantations with and without intercropped switchgrass. We used colored pan traps to capture bees during the growing seasons of 2013 and 2014. We captured 2507 bees comprised of 18 different genera during the two-year study, with Lasioglossum and Ceratina being the most common genera captured. Overall, bee abundances were dependent on plantation age and not presence of intercropping. Our data suggests that switchgrass does not negatively impact or promote bee communities within intensively-managed loblolly pine plantations.

Highlights

Over 87% of all angiosperms are dependent on pollination services [1] and approximately 75% of the main global food crops are dependent on insects for those services [2]
We used three replicates of four treatments, each approximately 8 ha in size: 3–4 year old intensively managed pine plantations, 3–4 year old intensively managed pine plantations with switchgrass grown between rows
9–10 year old intensively managed pine plantations with switchgrass grown between rows

Summary

Introduction

Over 87% of all angiosperms are dependent on pollination services (primarily derived from insects) [1] and approximately 75% of the main global food crops are dependent on insects for those services [2]. Intercropping switchgrass in the inter-bed area (space between rows of planted trees) of pine plantations may augment ethanol production while limiting future land conversion to biofuel crops (e.g., corn). Switchgrass and pine are wind-pollinated crops and these species would not contribute greatly to diets of foraging pollinators, managed forests can provide nesting habitat and other structure needed by native bees and beneficial insects [18]. Communities, little is known about how biofuel feedstock intercropping could affect biodiversity [22] of bees in a managed forest system. We examined potential effects of intercropping switchgrass in intensively managed loblolly pine plantations on bee communities by testing whether stand age and intercropping influenced bee abundance and diversity. We hypothesized that intercropping switchgrass between loblolly pine rows would affect some bee species by reducing plant diversity in the interbed area. We hypothesized that our older pine stands may provide increased coarse woody debris that could be used as nesting sites for many wood/stem nesting bees

Site Location and Preparation

Insect Trapping

Insect

Statistical Analysis

Results

Conclusions