Influence of intercropping switchgrass in intensively managed pine forests on ultrasound produced by bats and rodents

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Ashley M. Matteson (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
Advisor
Matina Kalcounis-Rueppell

Abstract: Intensively managed pine forests provide habitat for a diversity of wildlife species, including bats and rodents. In Kemper Co., MS, USA, Weyerhaeuser Company and Catchlight Energy LLC, on land owned and managed by Weyerhaeuser, intercrops `Alamo' switchgrass (Panicum virgatum L.) between rows of pines in managed loblolly pine (Pinus taeda) plantations. I considered whether switchgrass intercropping in pine plantations results in differences in understory vegetation density, affects propagation of ultrasound, and affects acoustic signals of bats and rodents when compared to non-intercropped pine plantations. Treatments included traditionally managed pine plantations (P), pine plantations intercropped with switchgrass (PxS), and a no vegetation control (C). I measured understory vegetation density to determine if switchgrass intercropping increased understory vegetation density. I used broadcasting experiments to determine if treatment influences the absorption of sound energy and the distance ultrasound travels. I recorded bat and rodent ultrasound to determine if they are altering the spectral and temporal characteristics of their vocalizations in response to treatment. Understory vegetation density was higher in the PxS treatment, but both treatments had dense vegetation in the understory. The absorption coefficient was largest and sounds travelled the shortest distance in the PxS treatment plots, where vegetation density was highest. In P treatment plots, the absorption coefficient and the distance sound travelled were both intermediate. The absorption coefficient was smallest and sounds travelled the longest distance in the C treatment, where there was no vegetation present. I found no evidence to suggest that either bats or rodents are altering the spectral and temporal characteristics of vocalizations. Increased vegetation density could affect rodents living in the understory, because sound produced in habitat with dense vegetation are attenuated quickly. Rodents may respond to increased vegetation density by altering the spectral and temporal characteristics to improve sound transmission. Rodents may also respond to increased vegetation density by reducing the amount of ultrasonic vocalizations they produce and/or stop producing ultrasonic vocalizations, due to reduced signal effectiveness. Failure to detect signals in my system may or may not lead to decreased reproductive success of individuals, but more research needs to be done to fully understand the implications of reduced signal transmission on rodents.

Additional Information

Publication
Thesis
Language: English
Date: 2013
Keywords
Bats, Broadcasting, Habitat change, Rodents, Ultrasound, Vegetation density
Subjects
Bats $x Effect of forest management on $z North Carolina
Bats $x Vocalization
Rodents $x Effect of forest management on $z North Carolina
Rodents $x Vocalization
Loblolly pine $x Research $z North Carolina
Switchgrass $x Research $z North Carolina
Forest management $x Research $z North Carolina

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