Thinning P. taeda improved richness and abundance for four taxonomic groups: A case study at Cowan's Ford Wildlife Refuge in Huntersville, North Carolina

Caroline Brinegar and Lenny Lampel, Park and Recreation (Natural Resources Division), Mecklenburg County, Charlotte, NC

Background/Question/Methods
Though not a native part of the forested landscape, Loblolly pine (Pinus taeda) stands were abundant in the Piedmont region of North Carolina for a long period of time. P. taeda stands--planted as a monoculture for commercial harvest-- are frequently inherited by the county when parcels are acquired for purposes including land and water conservation. One such case occurs within the Cowan’s Ford Wildlife Refuge, a controlled access nature preserve and designated State Natural Heritage Area bounded on three sides by the Catawba River.
Keeping natural communities in the best quality and condition as possible and increasing native biodiversity are important priorities for the Mecklenburg County Division of Nature Preserves and Natural Resources. Loblolly pine stands are counter to these objectives because they produce a single species monoculture that provides limited benefits to wildlife. The preferred forestry practice of removing P. taeda and subsequently replanting with Shortleaf pine (Pinus echinata) was not an option at this site due to its topography, which contains steep slopes and pronounced ridges, and the potential for water quality issues given its proximity to Duck Cove, a protected area characterized by rare flora and otherwise high quality habitat. Another important forest management tool, thinning rather than removing P. taeda was identified as the best option for minimizing erosion and maximizing biodiversity by improving habitat quality and resource availability within the site.
Data were collected for one field season prior to thinning (2015) and for three seasons after, spanning six total (not necessarily consecutive) weeks between mid-September and mid- October of 2016, 2017, and 2018. The effects of thinning on four taxonomic groups was assessed: small mammals, vegetation, two insect orders, and avifauna.


Results/Conclusions
Preliminary findings from linear models generally indicate a significant increase in richness for all four taxonomic groups studied and abundance for three groups in the season immediately following forest management. Additional changes in diversity and composition over time can be explained by this management technique when coupled with additional moderators, including weather and the impacts of a prescribed burn.
These findings support thinning as a viable forest management alternative in cases where the removal of P. taeda is not feasible, and highlight the potential for short term and long term benefits to local habitat quality and terrestrial biodiversity, viable management alternatives, and improved public perception of tree removal in nature preserves.