Effect of Removal of Woody Biomass after Clearcutting and Intercropping Switchgrass (Panicum virgatum) with Loblolly Pine (Pinus taeda) on Rodent Diversity and Populations

Abstract

<jats:p>Plant-based feedstocks have long been considered viable, potential sources for biofuels. However, concerns regarding production effects may outweigh gains like carbon savings. Additional information is needed to understand environmental effects of growing feedstocks, including effects on wildlife communities and populations. We used a randomized and replicated experimental design to examine initial effects of biofuel feedstock treatment options, including removal of woody biomass after clearcutting and intercropping switchgrass (<jats:italic>Panicum virgatum</jats:italic>), on rodents to 2 years post-treatment in regenerating pine plantations in North Carolina, USA. Rodent community composition did not change with switchgrass production or residual biomass removal treatments. Further, residual biomass removal had no influence on rodent population abundances. However,<jats:italic>Peromyscus leucopus</jats:italic>was found in the greatest abundance and had the greatest survival in treatments without switchgrass. In contrast, abundance of invasive<jats:italic>Mus musculus</jats:italic>was greatest in switchgrass treatments. Other native species, such as<jats:italic>Sigmodon hispidus</jats:italic>, were not influenced by the presence of switchgrass. Our results suggest that planting of switchgrass, but not biomass removal, had species-specific effects on rodents at least 2 years post-planting in an intensively managed southern pine system. Determining ecological mechanisms underlying our observed species associations with switchgrass will be integral for understanding long-term sustainability of biofuels production in southern pine forest.</jats:p>

Effects of habitat modification on cotton rat population dynamics and rodent community structure

“…Previous studies of switchgrass intercropping suggested a possible association between switchgrass and non-native, invasive house mice Marshall et al, 2012). Although our study detected house mice in initial years in plots where switchgrass was planted, by year three, we no longer detected house mice in any plots.…”

“…Furthermore, house mice are seminomadic and may have simply immigrated to an area of newly disturbed land given the landscape is a matrix of actively managed pine plantations (Caldwelll and Gentry, 1965). Therefore, house mice are more likely associated with initial disturbance of planting switchgrass and with agricultural fields that surrounded plots in a previous study than with switchgrass directly Marshall et al, 2012).…”

“…However, there is a potential for further change as forest succession continues in the intercrop and control treatment plots (Loman et al, 2014). There is a need for research on effects of planting switchgrass on biodiversity, particularly in intercropped stands (Riffell et al, 2012), because most studies that have examined effects of switchgrass on biodiversity have both compared switchgrass to row crops and native grasslands (Fletcher et al, 2010) and investigated effects on grassland birds and herpetofauna Loman et al, 2014) rather than mammals (but see Briones et al, 2013;Homyack et al, 2014;King et al, 2014;Marshall et al, 2012).…”

“…Different rodent species prefer different habitat conditions, so vegetative heterogeneity throughout an area support a more diverse rodent community (Dueser and Shuggart, 1979;Mengak and Guynn, 2003). Abundance of white-footed mice (Peromyscus leucopus) has been negatively correlated with grass cover while cotton rat (Sigmodon hispidus) captures have been positively correlated with grass cover (Marshall et al, 2012;Mengak and Guynn, 2003). A previous study investigating functional role of white-footed mice in a switchgrass intercropped in a pine system in North Carolina, USA found that there were no differences in carbon or nitrogen isotope signatures between white-footed mice in switchgrass intercropped plots and pine plantation plots, suggesting no change in their functional role (Briones et al, 2013).…”

Rodent population and community responses to forest-based biofuel production

“…Although intercropping can change vegetative structure of the understory, our results in conjunction with previous research indicate that wildlife communities in pine plantations are often similar despite whether switchgrass was intercropped or biomass was harvested. For example, rodent, herpetofauna, and avian richness and diversity were either unaffected by intercropping switchgrass, or converged to that of pine plantations by 3 years after switchgrass establishment (Marshall et al , Homyack et al , Loman et al ). Further, the ecological role and trophic position of omnivorous white‐footed mice was not affected by intercropping a potential food source, switchgrass (Briones et al ).…”