Wildlife and Habitats in Managed Landscapes

by Jon Rodiek (Editor), Eric Bolen (Editor)

Overview

Americans are having an increasing impact on the rural landscape as development further encroaches in former wilderness areas. This disruptive land use is causing a decline in wildlife and wildlife habitats. Wildlife and Habitats in Managed Landscapes presents a new strategy for solving this problem by redefining habitats to include the concept of landscape. Employing this strategy, natural resource managers apply tools of planning, management, and design to entire landscapes to meet the needs of both wildlife and humans.

Product Details

ISBN-13:	9781610913706
Publisher:	Island Press
Publication date:	04/24/2013
Sold by:	Barnes & Noble
Format:	eBook
Pages:	238
File size:	36 MB
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About the Author

Jon E. Rodiek is a professor of landscape architecture and urban and regional planning at the College of Architecture, Texas A & M University. He has degrees in Landscape Architecture (B.L.A., M.L.A.), Plant Science (B.S.), Forestry (M.S.), and Natural Resource Management (Ph.D.).

Eric G. Bolen currently is dean of the graduate school at the University of North Carolina at Wilmington. He has a B.S. from the University of Maine, and his M.S. and Ph.D. degrees from Utah State University.

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Wildlife and Habitats in Managed Landscapes

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By Jon E. Rodiek, Eric G. Bolen

ISLAND PRESS

Copyright © 1991 Island Press
All rights reserved.
ISBN: 978-1-61091-370-6

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CHAPTER 1

Powerline Corridors, Edge Effects, and Wildlife in Forested Landscapes of the Central Appalachians

J. EDWARD GATES

HUMAN DOMINATION of the landscape assumes a variety of forms. The process of urbanization produces perhaps the most noticeable forms.

Associated with this process are the landscape conversions that result from connecting many urban centers scattered throughout a larger natural ecosystem. We are referring to the powerline, gas pipeline, and highway right-of-way corridors that crisscross the landscape.

When corridors are cut through forested landscape, such as those found in the central Appalachians, several changes occur simultaneously. First, there is a physically dramatic disruption to the continuous vegetative community Second, there is a disruption to the structure and function of the wildlife habitats. Finally, there are impacts to the resident wildlife, which must negotiate, tolerate, or otherwise cope with these disturbances.

Urbanization fragments the natural ecosystem into smaller, less cohesive pieces of landscape. This fragmentation process raises many questions for the landscape manager concerned with wildlife. How do these large, spatial-scale landscape disturbances affect regional wildlife and habitat resources? Will wildlife be able to cope with this ever-growing process of reshaping the wild environment? Are there ways to optimally construct corridors in order to reduce the impacts they will have on the region's wildlife and habitat resources?

Research wildlife biologists have discovered that the predictability of these effects on wildlife habitats is not as optimistic as once believed. Dr. Gates focuses his attention on the effects of changes in the wildlife habitats found in and around corridors in the forested landscape of the central Appalachians. His studies lend insight to the various ways corridors function within the forest matrix as special habitats, as behavioral barriers, as filters to the movement of wildlife, and as a source of influences on the larger forest matrix.

The work represented by Gates and others has at least two important effects. First, it points out the need to conduct research that creates options for wildlife habitats formed within this new landscape mosaic. Second, it suggests that corridors may be a modern-day necessity in the central Appalachians. His work presents certain opportunities to design, plan, construct, and maintain corridors incorporating concerns for wildlife and habitats in this forest.

INTRODUCTION

Depending upon the surrounding background habitat or matrix, corridors in the landscape can be categorized as either of two major structural types. Convex corridors, such as hedgerows or forested stream corridors in agricultural areas, have greater height than the adjacent matrix. Concave corridors, on the other hand, are characterized by lower heights than the surrounding matrix. Powerlines, gas pipelines, and highway rights-of-way in forested areas are examples of concave corridors. Each type has unique properties and special characteristics that influence the local wildlife populations (Forman and Godron 1986).

Corridors function in a variety of ways within the matrix. For example, they may function as specialized habitats, as behavioral barriers or filters to the movement of wildlife, and as a source of effects on the matrix (Forman 1987). Furthermore, they may link together different patches in the matrix, providing travel lanes for animals between patches (Forman 1987, Harris 1988, Lines and Harris 1989). The way a corridor functions depends on several factors, including the animal species or species assemblage under consideration. Factors that influence how, when, and why animals use corridors include the composition and structure of the plant community within and adjacent to the corridor, the nature of the edge between the corridor and matrix, the size and shape of the corridor, and the microenvironment within the corridor, as well as whether the corridor is nested within other corridors. A highway corridor within a wooded corridor through an agricultural region functions much differently from a highway corridor through a forested region, even though forests border both highway corridors. The phenology and stability of the vegetation within corridors also influence animal use of corridors seasonally, as well as over successional time periods.

This study addresses two major questions related to powerline corridors and animal species or species assemblages in forested landscapes of the central Appalachians. First, how do the activity patterns of animals differ among the major habitat types composing the corridor, edge, and forest? Second, what effects do specific corridor management practices have upon these activity patterns?

The Landscape Setting

The ridge and valley physiographic province of western Maryland was the location for the research. It is characterized by long, parallel ridges and intervening valleys oriented in a southwesterly to northeasterly direction. This region is bracketed by South Mountain in Washington County and Dans Mountain in western Allegany County. It contains strongly folded and faulted sedimentary rocks. The Great Valley in the eastern part of the region is formed on Cambrian and Ordovician limestone and dolomite. Farther west, a more rugged terrain has developed upon shale and sandstone bedrock that dates from the Silurian to Mississippian periods. There, some valleys are underlain by Silurian and Devonian limestones.

Within the western part of the region, two study sites, Green Ridge and Warrior Mountain, were selected along a 138 kV powerline corridor in Allegany County. This county has 83,603 ha, or 75.8% of the land area, in forestland. Of the productive forestland, 73.0% is in private ownership with most of the remainder in state forest, wildlife management areas, and parks. Two-thirds of the forestlands are classified as oak-hickory; a contiguous oak-hickory forest bordered both study sites. Overstory species included red (Quercus rubra), black (Q. velutina), and chestnut (Q. prinus) oaks; pignut (Carya glabra) and mockernut (C. tomentosa) hickories; and widely scattered pines (Pinus virginiana and P. rigida). The moderately dense (> 30% to 60% cover) understory was a mixture of oak, hickory, flowering dogwood (Cornus florida), red maple (Acer rubrum), and black gum (Nyssa sylvatica). Forest ground cover ranged from moderate (> 30% to 60%) to dense (> 60%), depending upon nearness to water, slope, or presence of canopy gaps. Species included seedlings of the understory and overstory trees, bracken fern (Pteridium aquilinum), common greenbrier (Smilax rotundifolia), and blueberry (Vaccinium sp.). This region receives 91.4 to 101.6 cm of rainfall annually.

GREEN RIDGE

This study site was located on the eastern slope of Green Ridge in Green Ridge State Forest. An herbaceous corridor was mowed with a rotary mower by personnel from the Maryland Forest, Park, and Wildlife Service on 5 August 1977, prior to and during the study on 18 July 1978, but not during the summer of 1979. Prior to mowing in 1978, the mean vegetation height was 27.6 cm (± 1.46 SE, N = 50); after mowing, vegetation height was reduced to 9.2 cm (± 0.83 SE, N = 25). Because of heavy rain, approximately 24.6 cm in July and August, the grasses in the corridor quickly recovered following mowing. The predominant grasses were orchard (Dactylis glomerata), redtop (Agrostis alba), and several panic (Panicum spp.) grasses. Forbs included spreading dogbane (Apocynum an-drosaemifolium), bracken fern, and lespedezas (Lespedeza cuneata and L. bicolor). Three lobes extending from the forest edge into the corridor were inaccessible to the mower and were dominated by blackberry (Rubus allegheniensis). The high-contrast linear edge was composed of seedlings and saplings of red, black, and chestnut oaks with a ground cover of orchard and redtop grasses, bracken fern, and small, scattered blackberry patches. The corridor width averaged 46 m (± 0.43 SE, N = 35). The site increased gradually in elevation from approximately 335 m to 427 m. It was crossed by one perennial stream and two intermittent tributaries. Soils included well-drained shaley silt loam and very stony loam.

WARRIOR MOUNTAIN

This study site was located on the eastern slope of Warrior Mountain in Warrior Mountain Wildlife Management Area. This shrubby corridor was managed for selected woody plant species by spraying with herbicides at 1- to 3-year intervals. Prior to the fieldwork, the most recent application occurred on 2 January 1978, when a mixture of 13.2 1 of Tordon 155 and 365.3 1 of no. 2 fuel oil was applied as a basal spray to certain target species. The most abundant shrub species was blackberry. Other species included staghorn sumac (Rhus typhina), mountain laurel (Kalmia latifolia), blueberry (V. angustifolium and V. vacillans), bear oak (Q. ilicifolia), and seedlings and saplings of sassafras (Sassafras albidum) and red maple. These species often were scattered throughout the corridor in small, irregular patches. Many small (< 8 cm dbh) snags were also present. Bracken fern, hayscented fern (Dennstaedtia punctilobula), whirled loosestrife (Lysimachia quadrifolia), and several species of panic grasses were the principal herbs. The two ferns often were found in large, homogeneous patches. Whirled loosestrife was prevalent throughout the corridor. The linear edge was of high contrast but less so than at Green Ridge. It was dominated by seedlings and saplings of red, black, and chestnut oaks, many of which later died from herbicide spraying. Large patches of blackberry and bracken fern extended from the edge into the corridor, providing some irregularity to an otherwise linear edge. The corridor averaged 52 m (± 0.60 SE, N = 35) in width. The site increased rapidly in elevation from about 335 m to 610 m. It was crossed by one small intermittent stream. Soils were well-drained cherty silt loam and stony sandy loam.

THE APPROACH

Activity patterns of animals were determined by recording the number and location of crossings (i.e., a line of tracks left by an animal) made by different species or species assemblages over a 24-hour period on a sand-tracking surface measuring 0.61 m by 29.26 m (Bider 1968). Three such surfaces or transects were constructed at each site. A corridor transect was directly below, and parallel to, the center powerline; an edge transect, including both the corridor and forest edge, was perpendicular to, and bisected by, the forest boundary; and a forest transect was parallel to, and 60 m north of, the forest boundary. Most mammals were identified to species, but shrews were identified only to family. Other animal species were grouped according to lowest taxon (Table 1.1.). For example, birds were grouped into the Class Aves.

Transects were checked in early morning, and all tracks erased immediately afterward. Weather was noted after checking the transects and over the previous 24 hours. Each transect could be checked in 0.5 hour. Sampling periods covered 14 consecutive days in each of the months from May through August 1978 and 1979. Heavy rain in July 1978 resulted in data collection for only 10 days at Warrior Mountain and 13 days at Green Ridge. A transparent polyethylene plastic cover over a wooden A-frame helped to keep the sand-tracking surface dry.

Habitat-specific Activity Patterns of Mammal Species and Species Assemblages

GREEN RIDGE

Because of overlap within the edge of species more characteristic of either the forest or corridor, richness was 1 to 3 species higher in the edge than within adjacent habitats (Fig. 1.1.). The mammalian assemblage had fewer crossings on the corridor transect compared with transects in the other two habitats (Table 1.2.). Mammal species or species assemblages were grouped according to their response to the three habitat types. Species or groups showing a filtering effect or avoidance of the corridor included the gray squirrel, red squirrel, white-footed mouse, and raccoon; avoidance of the forest was exhibited by the house cat and meadow vole, a potential prey species. A behavioral barrier at the corridor edge was shown by the eastern chipmunk in 1978 and 1979, and by the woodchuck in 1978. In 1979, the woodchuck showed similar activity in the edge and forest. This species inhabits open fields and forest edges. Shrews were quite variable in their response to the habitat types from one year to the next. In 1978, there was no significant difference in number of crossings among habitat types, whereas in 1979 shrews showed a corridor avoidance response. This change could be related to differences in activity patterns from one year to the next or to changes in shrew species composition. However, most crossings were thought to be made by the common short-tailed shrew, especially within the corridor. Shrews may have been responding to movements by one or more prey species (e.g., snail/slug activity in 1979; Table 1.3.). The opossum was recorded on the study site in the second year. Although this forest species seemed to respond to the corridor as a barrier, the high activity within the edge could also have resulted from its use as a travel lane.

WARRIOR MOUNTAIN

Differences in species richness among the three habitat types in 1978 were slight with the forest and/or edge having one species more than the corridor. In 1979, the edge had one to two species more than the forest or corridor as a result of the additive effect of species from the adjacent habitats (Fig. 1.1.). The mammalian assemblage had lower numbers of crossings on the corridor transect compared with the other two habitats, and slightly more crossings on the edge (Table 1.2.). More activity occurred on the Warrior Mountain corridor transect than occurred at Green Ridge in both 1978 (X2 = 237.27, df = 1, P< 0.001) and 1979 (X2 = 167.05, df = 1, P< 0.001). Avoidance of the shrubby corridor was exhibited by the gray squirrel, red squirrel, eastern wood rat, raccoon, and dog. The gray squirrel responded to the corridor as a behavioral barrier, as did the raccoon in 1978. A wood rat den site was observed in a rocky ravine within the forest interior. Species that exhibited avoidance of the forest included the red fox and striped skunk. Both species prefer farmland, sparsely wooded areas, brushlands, and dense weed patches, usually near a stream or lake. These two mammals perhaps used the corridor and edge as travel lanes. Species responding to the corridor as a barrier to movement included shrews in 1979 and the eastern chipmunk in 1978. The movements of the eastern chipmunk significantly increased in the corridor from 1978 to 1979 (X2 = 395.42, df = 1, P< 0.001) when greater vegetative cover likely provided more protection from hawks and other predators, as well as possibly increased foraging success. The fox, a potential predator of the chipmunk, also increased its use of the corridor in 1979. The shrubby corridor was less of an aversion to gray squirrels (1978: X2 = 51.52, df = 1, P < 0.001; 1979: X2 = 2.88, df = 1, P < 0.05) and white-footed mice (1978: X2 = 517.13, df = 1, P< 0.001; 1979: X2 = 37.84, df = 1, P< 0.001) than was the herbaceous corridor. Although white-footed mouse activity differed significantly among habitat types at Warrior Mountain, the percentage differences were slight and undoubtedly resulted from the large sample size.

Habitat-specific Activity Patterns of Other Animal Groups

GREEN RIDGE

The animal-tracking technique was effective only in sampling ground-foraging birds [e.g., the indigo bunting (Passerina cyanea), rufous-sided towhee (Pipilo erythrophthalmus), and field sparrow (Spizella pusilla)]. Birds had more crossings on the edge transect than on either the corridor or forest (Table 1.3.). Rather than functioning as barrier or filter, edge-adapted birds were merely using this specialized habitat for foraging. Snakes were also more active at the edge. Snakes included the timber rattlesnake (Crotalus horridus horridus), milksnake (Lampropeltis triangulum triangulum), black rat snake (Elaphe obsoleta obsoleta), black racer (Coluber constrictor constrictor), garter snake (Thamnophis sirtalis sirtalis), and hognose snake (Heterodon platyrhinos). The black rat snake tends to be associated with forest edges (Weatherhead and Charland 1985, Gibbons and Semlitsch 1987, Durner and Gates unpubl.). Snakes may have been responding to higher numbers of prey in the edge, based upon activity patterns of chipmunks, birds, and toads. Turtles, primarily box turtles (Terrapene carolina), appeared to avoid the corridor in 1978, but exhibited no difference among habitat types in 1979. Salamanders and lizards made more crossings on the edge transect. Toads were generally more active on the edge than in the forest or corridor. Arthropods, primarily ground-dwelling insects, centipedes, and millipedes, were quite variable in their use of habitat types from one year to the next. Activity in 1978 was slightly higher in the corridor, whereas in 1979 the edge had the higher number of crossings. Earthworm activity was highest in the corridor and then the forest. Snails and slugs in 1978 were more active in the edge; in 1979, this group was more active in the forest.

(Continues...)

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Excerpted from Wildlife and Habitats in Managed Landscapes by Jon E. Rodiek, Eric G. Bolen. Copyright © 1991 Island Press. Excerpted by permission of ISLAND PRESS.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents

Acknowledgments
Foreword
 
Introduction
Chapter 1. Powerline Corridors, Edge Effects, and Wildlife in Forested Landscapes of the Central Appalachians
Chapter 2. Windbreaks, Wildlife, and Hunters
Chapter 3. Managed Habitats for Deer in Juniper Woodlands of West Texas
Chapter 4. Browse Diversity and Physiological Status of White-tailed Deer during Winter
Chapter 5. Conservation of Rain Forests in Southeast Alaska: Report of a Working Group
Chapter 6. American Marten: A Case for Landscape-Level Management
Chapter 7. Planning for Basin-Level Cumulative Effects in the Appalachian Coal Field
Chapter 8. Breeding Bird Assemblages in Managed Northern Hardwood Forests in New England
Chapter 9. Wildlife Communities of Southwestern Riparian Ecosystems
 
List of Authors
Index