DOI: 10.5061/dryad.69p8cz8z3
title: Bat community response to intensification of biomass production for bioenergy across the southeastern United States

description: Human demand for food, fiber, and space is accelerating the rate of change
 of land cover and land use. Much of the world now consists of a matrix of
 natural forests, managed forests, agricultural cropland, and urbanized
 plots. Expansion of domestic energy production efforts in the United
 States is one driver predicted to influence future land-use and land
 management practices across large spatial scales. Favorable growing
 conditions make the southeastern United States an ideal location for
 producing a large portion of the country’s renewable bioenergy. We
 investigated patterns of bat occurrence in two bioenergy feedstocks
 commonly grown in this region (corn, Zea mays, and pine, Pinus taeda and
 P. elliottii). We also evaluated potential impacts of the three major
 pathways of woody biomass extraction (residue removal following clearcut
 harvest, short-rotation energy plantations, and mid-rotation forest
 thinning) to bat occurrence through a priori land-use contrasts. We
 acoustically sampled bat vocalizations at 84 sites in the Southeastern
 Plains and Southern Coastal Plains of the southeastern United States
 across three years. We found that mid-rotation thinning resulted in
 positive effects on bat occurrence, and potential conversion of unmanaged
 (reference) forest to managed forest for timber and/or bioenergy harvest
 resulted in negative effects on bat occurrence when effects were averaged
 across all species. The effects of short-rotation energy plantations,
 removal of logging residues from plantation clearcuts, and corn were
 equivocal for all bat species examined. Our results suggest that
 accelerated production of biomass for energy production through either
 corn or intensively managed pine forests is not likely to have an adverse
 effect on bat communities, so long as existing older unmanaged forests are
 not converted to managed bioenergy or timber plantations. Beyond bioenergy
 crop production, mid-rotation thinning of even-aged pine stands intended
 for timber production, increases to the duration of plantation rotations
 to promote older forest stands, arranging forest stands and crop fields to
 maximize edge habitat, and maintaining unmanaged forests could benefit bat
 communities by augmenting roosting and foraging opportunities.
description: As part of a large investigation on bioenergy and biodiversity,
 we collected bat occurrence and activity data from 84 study sites
 stratified across three broad geographic regions in the states of Alabama,
 Florida, and Georgia, USA. We selected sites so that they occurred in
 eight different land use types: clearcuts (0-3 years post-harvest) with
 logging residues removed, clearcuts of similar age with residues retained,
 young plantations (8-10 years), mature plantations (20-32 years), recently
 thinned stands (12-16 years), stands of similar age (12-16 years) that
 were not thinned, corn fields, and natural (unplanted) mature pine stands.
 The latter were natural forests of longleaf pine (<i>Pinus
 palustris</i>) representative of the historical conditions that
 prevailed across the study region prior to the advent of modern
 agricultural and forestry production. All other forest surveys occurred in
 plantations of slash pine (<i>P. elliottii</i>) and loblolly
 pine (<i>P. taeda</i>), the two most common species grown for
 timber in the region. We surveyed bat activity by
 recording bat echolocation calls. We placed four Anabat II echolocation
 detectors coupled with Zero Crossing Analysis Interface Modules (ZCAIMS,
 Titley Electronics, Ballina, NSW, Australia) simultaneously at each study
 site on 336 nights between late March and late July during 2013-2015. Two
 detectors were placed at the center of each site and two near the edge. We
 attempted to survey each site four times per field season. Detectors were
 programmed to turn on 30 min prior to sunset and off 30 min after
 sunrise. We used Kaleidoscope Pro 3.14B (Wildlife
 Acoustics, Inc.) with the ‘Bats of Florida Classifier’ (3.1.0) to identify
 and analyze calls. We used the “balanced” sensitivity/accuracy setting in
 Kaleidoscope Pro (which gives parity to both sensitivity and accuracy) and
 assessed all files with characteristics of more than one species,
 retaining only those in which &gt;50% of the calls matched the species
 identification assigned by the software.