White‐tailed deer carrying capacity, intercropping switchgrass, and pine plantations

Abstract

Switchgrass (Panicum virgatum) is a cellulosic feedstock for alternative energy production that can be grown between rows of planted pines (Pinus spp.) within intensively managed forests. Southeastern planted pine occupies 15.8 million ha and thus, switchgrass intercropping could have far‐ranging effects on plant communities and biomass production within these forests if broadly implemented. Such intercropping could lead to alterations to plant communities that may cause bottom‐up ecological changes affecting ecologically, economically, and socially important wildlife, such as white‐tailed deer (Odocoileus virginianus; deer). Therefore, we tested whether intercropping switchgrass in loblolly pine (P. taeda) plantations would cause switchgrass to dominate vegetative biomass thereby decreasing biomass of forages and reducing white‐tailed deer nutritional carrying capacity (NCC), or whether disturbance associated with establishment and harvest of switchgrass would facilitate ruderal forbs, and thereby increase biomass of preferred deer forages and increase NCC. In a randomized complete block design, we assigned 2 treatments (intercropped switchgrass and a standard pine management control) to 4 replicates of 10‐ha experimental units in Kemper County, Mississippi during summers of 2011−2015. We detected 323 plant species. Intercropping switchgrass had little effect on plant biomass production, and did not affect white‐tailed deer NCC at a maintenance diet of 6% crude protein. Intercropping provided additional disturbance allowing high‐protein content ruderal plants to colonize, and temporarily increased (3 yr) deer NCC at the 14% crude protein diet considered necessary to support lactation. However, concomitant with a sharp increase in switchgrass biomass in the third year of the study, NCC dropped to levels similar to traditionally managed pine stands. Switchgrass intercropping is not a reliable means of increasing deer NCC as a management strategy but does not appear to reduce carrying capacity in the short‐term relative to standard intensive pine management. © 2017 The Wildlife Society.

Nest survival modelling using a multi‐species approach in forests managed for timber and biofuel feedstock

“…Traditional pine (PC), the reference treatment, was assigned to two plots in each stand, and used standard Weyerhaeuser silvicultural treatments for site preparation and loblolly pine management including a combination v‐blade bedding plow and a subsoil ripper to establish pine beds, pine seedlings planted on a 1.5 × 6.1 m grid (1,100 trees × ha −1 ), and banded herbicide applications of imazapyr (0.29 L/ha; Arsenal ® AC, BASF Corp., Research Triangle, NC) and sulfometuron‐methyl (0.15 L/ha; Oust ® , E. I. du Pont Nemours and Company, Wilmington, DE) for woody competition control (Loman, Monroe, et al., ; Loman, Riffell, et al, ). The intercropped switchgrass (IC) treatment was established following site preparation through standard management practices with additional seeding of switchgrass between beds of pine trees following additional clearing of downed coarse woody debris within the interbed area, which was then disked and sprayed with a banded application of glyphosate (2.34–4.68 L/ha; Accort ® XRT, Dow AgroSciences, Indianapolis, IN) prior to seeding (Loman, Riffell, Miller, Martin, & Vilella, ; Loman, Monroe, et al, ; Loman, Riffell, et al, ). The remaining six of 24 plots were 10‐ha subplots selected from older, variable‐size pre‐existing intercropped stands (hereafter “older intercropped” or “OI”) where switchgrass was established in 3‐year‐old pine plantations rather than at time of planting.…”

“…Data available from the Dryad Digital Repository https://doi.org/10.5061/dryad.7sc06 (Loman, Monroe, et al, ).…”