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Anderson, Greg S.; Danielson, Brent J.

doi:10.1023/a:1007933623979

Cited by 72 publications

(6 citation statements)

References 23 publications

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“…Some authors equate connectivity to the presence and absence of corridors between small fragments (e.g., Hess 1996;Swart and Lawes 1996;Anderson and Danielson 1997;Ims and Andreassen 1999;Danielson and Hubbard 2000;Hunter 2002), with corridor width (Andreassen et al 1996a), length (Haddad 2000) or corridor continuity (Andreassen et al 1996b). Thus no assumption is made about a particular animal, only the percentage of corridors between patches out of the possible number of corridors is considered as a measure of connectivity.…”

Section: Structural Definitionsmentioning

confidence: 99%

Connectivity measures: a review

2008

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One of the central problems in contemporary ecology and conservation biology is the drastic change of landscapes induced by anthropogenic activities, resulting in habitat loss and fragmentation. For many wild living species, local extinctions of fragmented populations are common and recolonization is critical for regional survival. Successful recolonization depends on the availability of dispersing individuals and the degree of landscape connectivity. The obvious implications of landscape connectivity for conservation biology have led to a proliferation of connectivity measures. However, general relationships between landscape connectivity and landscape structure are lacking, and so are the relationships between different connectivity metrics. Consequently, there is a need to develop landscape metrics that more accurately characterize the landscape with an emphasis on the underlying processes. Here we review various definitions of landscape connectivity, explain their mathematical connotations, and make some unifying conclusions and suggestions for future research.

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Section: Structural Definitionsmentioning

confidence: 99%

Connectivity measures: a review

2008

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“…A lack of connectivity due to habitat fragmentation may lead to modifications in the behavior of animals, for example, changes in home range size and location or changes in movement patterns (Trombulak and Frissell 2000), and Anderson and Danielson (1997) showed that corridor quality and arrangement will affect meta-population dynamics. Furthermore, Coulon et al (2004) found evidence that gene flow in roe deer ( Capreolus capreolus ) was influenced by the connectivity of the landscape.…”

Section: Introductionmentioning

confidence: 99%

Analyses of least cost paths for determining effects of habitat types on landscape permeability: wolves in Poland

et al. 2010

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Determining ecological corridors is crucial for conservation efforts in fragmented habitats. Commonly employed least cost path (LCP) analysis relies on the underlying cost matrix. By using Ecological Niche Factor Analysis, we minimized the problems connected with subjective cost assessment or the use of presence/absence data. We used data on the wolf presence/absence in Poland to identify LCPs connecting patches of suitable wolf habitat, factors that influence patch occupancy, and compare LCPs between different genetic subpopulations. We found that a lower proportion of cities and roads surrounds the most densely populated patches. Least cost paths between areas where little dispersal takes place (i.e., leading to unpopulated patches or between different genetic subpopulations) ran through a higher proportion of roads and human settlements. They also crossed larger maximal distances over deforested areas. We propose that, apart from supplying the basis for direct conservation efforts, LCPs can be used to determine what factors might facilitate or hinder dispersal by comparing different subsets of LCPs. The methods employed can be widely applicable to gain more in-depth information on potential dispersal barriers for large carnivores.

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“…The traditional corridor hypothesis posits that corridors act as dispersal conduits, channeling organisms between connected patches (3,4). The drift-fence hypothesis posits that corridors intercept organisms dispersing through matrix habitat and direct them into associated patches, thereby increasing colonization of patches with corridors, regardless of whether the corridors connect patches (10,11). These hypotheses are not mutually exclusive.…”

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confidence: 99%

“…These include the tandem repeatcontaining a and b antigens of the C protein complex (9) and Rib (10); surface immunogenic protein, Sip (11); and C5a-ase, a serine protease that inactivates complement factor C5a (12). However, of these proteins, only Sip and C5a-ase are conserved at the gene level in the majority of GBS isolates (11,13), and no systematic analysis on the extent of cross-protection is available.…”

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Effects of Landscape Corridors on Seed Dispersal by Birds

Levey

Bolker

Tewksbury

et al. 2005

Science

299

259

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Habitat fragmentation threatens biodiversity by disrupting dispersal. The mechanisms and consequences of this disruption are controversial, primarily because most organisms are difficult to track. We examined the effect of habitat corridors on long-distance dispersal of seeds by birds, and tested whether small-scale (G20 meters) movements of birds could be scaled up to predict dispersal of seeds across hundreds of meters in eight experimentally fragmented landscapes. A simulation model accurately predicted the observed pattern of seed rain and revealed that corridors functioned through edgefollowing behavior of birds. Our study shows how models based on easily observed behaviors can be scaled up to predict landscape-level processes.Habitat fragmentation poses a widespread threat to biodiversity by disrupting the dispersal of organisms (1, 2). Corridors-narrow strips of habitat that join patches of similar habitatare thought to provide a general solution by restoring dispersal among patches, thereby increasing gene flow and reducing the probability of local extinctions (3, 4). Yet corridors are controversial (5, 6). Their efficacy can vary greatly among systems, depending on the complex interaction between disperser behavior and landscape structure (3, 7). Controversy about corridors has been difficult to resolve because corridors operate at a landscape scale, where both experimental and observational (tracking) studies are difficult (8).Here we test and validate an alternative approach to examine corridor function: individualbased behavioral models (9). Our goal was to predict corridor effects on long-distance (9250 m) dispersal of seeds by birds. We collected data on small-scale (G20 m) movements of seeddispersing birds in experimental landscapes and used these movements to parameterize a model that predicted the effects of corridors on seed dispersal at the landscape scale. We then tested our model using data on actual seed rain from the same large-scale experimental landscapes. Importantly, our model links observations of local bird behavior to population-level impacts on the recruitment of plants, showing how corridor effects on one taxon can affect the other. More generally, the control and replication provided by our experimental landscapes allow a rigorous validation of individual-based models, which are widely applicable to other systems.Our experimental landscapes were designed to test two alternative hypotheses about how corridors function. The traditional corridor hypothesis posits that corridors act as dispersal conduits, channeling organisms between connected patches (3, 4). The drift-fence hypothesis posits that corridors intercept organisms dispersing through matrix habitat and direct them into associated patches, thereby increasing colonization of patches with corridors, regardless of whether the corridors connect patches (10, 11). These hypotheses are not mutually exclusive.Each of our experimental landscapes contained five patches of regenerating vegetation in a matrix of mature pine forest ( F...

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Untitled

Cited by 72 publications

References 23 publications

Connectivity measures: a review

Connectivity measures: a review

Analyses of least cost paths for determining effects of habitat types on landscape permeability: wolves in Poland

Effects of Landscape Corridors on Seed Dispersal by Birds

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