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647 results on '"WARREN, ROBERT J."'

4. Ants: Ecology and Impacts in Dead Wood

Author

King, Joshua R., Warren, Robert J., II, Maynard, Daniel S., Bradford, Mark A., Feldhaar, Heike, Series Editor, Schmidt-Rhaesa, Andreas, Series Editor, and Ulyshen, Michael D., editor

Published
2018
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13. Soil moisture mediated interaction between Polygonatum biflorum and leaf spot disease

Author

Warren, Robert J. and Mordecai, Erin

Subjects
Life Sciences, Plant Sciences, Disease ecology, Population dynamics, Biotic interactions, Perennial herb, Fungal pathogen, Southern Appalachian Mountains, Polygonatum biflorum, Phyllostica sp
Abstract

Fungal pathogens can regulate the abundance and distribution of natural plant populations by inhibiting the growth, survival, and reproduction of their hosts. The abiotic environment is a crucial component in host–pathogen interactions in natural plant populations as favorable conditions drive pathogen development, reproduction, and persistence. Foliar plant pathogens, such as fungal lesions referred to generically as “leaf spot disease,” are particularly responsive to increased moisture levels, but the manner in which the abiotic environment drives disease dynamics, and how these diseases regulate natural plant populations, is not fully understood. We investigate (1) the impact of ambient soil moisture and diffuse light on the prevalence of a leaf spot pathogen (Phyllosticta sp.) in a natural population of Polygonatum biflorum, an understory herb native to deciduous forest understories in the eastern US, and (2) the effects of the fungal pathogen on the survival, growth, and abundance of the plants. We tracked six P. biflorum populations and disease incidence, as well as soil moisture and diffuse light, between 2003 and 2005 in the understory deciduous forest of the southern Appalachian Mountains, North Carolina, USA. Results show that both the occurrence of P. biflorum and the prevalence of P. biflorum leaf spot disease are highest where soil moisture is intermediate and diffuse light is lowest. Disease occurrence depends upon plant presence, but it also adversely impacts plant survival, abundance, and growth. These results suggest that leaf spot disease is likely to impact population dynamics, which in turn vary as a function of environmental drivers.

Published
2010

20. Behavioral Responses of White-tailed Deer to Vehicle Mounted Sound-Producing Devices

Author

Valitzski, Sharon A., D'Angelo, Gino J., Osborn, David A., Miller, Karl V., Warren, Robert J., and Gallagher, George R.

Subjects
deer-vehicle collisions, sound treatment, captive deer, deer whistles
Abstract

Deer-vehicle collisions are on the rise and are a costly side-effect of increasing deer populations and expanding transportation systems. We evaluated the efficacy of sound as a deterrent for reducing deer-vehicle collisions by observing the behavioral response of captive and free-ranging white-tailed deer (Odocoileus virginianus) to 5 pure-tone sound treatments: 0.28 kHz, 1 kHz, 8 kHz, 15 kHz, and 28 kHz. We conducted preliminary trials with semi-tame deer at the University of Georgia Captive Deer Research Facility. We exposed 8 deer in a 0.25-ha outside paddock and 5 deer in individual stalls (2.7 m x 4.8 m) to the various treatments at >70 dB Sound Pressure Level. We recorded 406 observations and determined that the behavior of captive deer did not change when presented with any of the 5 pure-tone sound treatments. We also conducted field trials at Berry College Wildlife Refuge, Georgia and gathered 319 behavioral observations of free-ranging deer relative to a moving automobile (56.45 kph). The automobile was fitted with a sound-producing device and speakers that emitted one of the pure-tone sound treatments or no sound treatment as a control. For the 1 kHz, 8 kHz, 15 kHz, and 28 kHz sound treatments, we observed no change in deer behavior relative to the control. When exposed to the 0.28 kHz treatment, deer reacted in a manner more likely to cause deer-vehicle collisions. Our results indicate that deer within 10 m of roadways did not alter their behavior in response to the pure-tone sound treatments we tested in a manner that would prevent deer-vehicle collisions. Commercially available wildlife warning whistles (aka deer whistles) are purported to emit similar consistent, continuous sounds as pure tones at various frequencies within the range of those presented in this study. Our data suggests that deer-whistles, as they are purported to operate, are likely not effective in preventing deer-vehicle collisions.

Published
2007

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