Fencerows, Edges, and Implications of Changing Connectivity Illustrated by Two Contiguous Ohio Landscapes

Abstract

We evaluated the amounts and implications of changes in habitat connectivity on rural land‐scapes by modeling the colonization success and subsequent habitat colonization of a model edge organism within real landscapes. We first inventoried the changes in the fencerow and forest‐edge network of two contiguous Ohio (U.S.A.) landscapes, an agriculturally dominated till plain and a more diverse and dynamic moraine landscape, from 1940 to 1988. On the moraine the number of fencerows changed little from 1940 to 1971. The number increased by 86 during 1971–1988 as marginal farms were subdivided. The total length of fencerows on the moraine increased 2.5‐fold over 48 years. On the till plain the number and total length of fencerows remained relatively constant through the study period. The sum of fencerows and forest edges was used as a measure of total ecotonal edge. On the moraine total edge increased through the study period, whereas on the till plain it decreased. We selected two levels of landscape connectivity, low and high, to model animal habitat colonization success. As connectivity increased the earliest successful colonists preempted an increasingly large proportion of the total suitable habitat, and the probability of successful colonization by later‐arriving individuals decreased. The changes in connectivity that resulted from changes in both the fencerow network and the proportion of forested land have resulted in contiguous landscapes that present very different colonization potentials to organisms with long‐distance dispersal capability. Given the current uncertainty of the effects of corridors on species‐preservation efforts, we suggest that further modeling of this type prior to field testing will add useful insights, especially if conducted using specific species and landscape types. Las cercas, los bordes y las connotaciones de los cambios en la conectividad ilustrados por dos paisajes contiguos de Ohio

Bush, bugs, and birds; interdependency in a farming landscape

“…Hedgerows and field margins are excellent at providing birds with appropriate nesting, roosting and foraging habitats [2,6]. Not only do they fulfill these essential functions, but they also provide cover for local movements and can facilitate longer distance travels through different landscapes [2,10,11]. However, the value of these hedgerows to different bird species depends on a number of different factors such as hedgerow height, width, length, ditch dimensions, number of snags or number of trees [2,12].…”

The influence of hedge structure, management and landscape context on the value of hedgerows to birds: A review

“…Osborne, 1984;O'Connor, 1987;Johnson and Beck, 1988;Moles and Breen, 1995;Demers et al, 1995). The value of hedgerows for birds depends on a number of factors including hedge size and structure in relation to the habitat preferences of individual bird species, the density and spatial arrangement of hedgerows in the local landscape and the management of the hedgerows themselves and of their surroundings (e.g.…”

Effects of cognitive abilities on metapopulation connectivity

“…Computer simulations provide a possible alternative approach, allowing investigations on the potential effect of animal cognitive abilities and decision rules on metapopulation connectivity and colonization probability (Delmers et al 1995, Backer 1996, Lima and Zollner 1996, Schippers et al 1996, Schumaker 1996, Carter and Finn 1999, Tischendorf and Fahrig 2000, Moilanen and Hanski 2001). Simulations of animal dispersal have already been conducted by linking a model landscape with a model animal, characterized by behavioral rules and constraints such as habitat affinity (With and Crist 1995, With et al 1997, 1999) or physiological states (Blackwell 1997, Wu et al 2000).…”