Landscape connectivity: A conservation application of graph theory

Bunn, A. G.; Urban, Dean L.; Keitt, Timothy H.

doi:10.1006/jema.2000.0373

Cited by 516 publications

(443 citation statements)

References 27 publications

(39 reference statements)

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“…Forman 1995;Ims 1995;With and Crist 1995;With et al 1997;Wiens 1997;Bunn et al 2000;Solé and Bascompte 2006). For example, brown kiwi (Apteryx australis) has been observed to cross 80 m between forest patches readily, but greater distances significantly decreased the chance of colonization; a 500-m distance proved to be impassable (Potter 1990).…”

Section: An Outlook To the Significance Of Fragmentation At The Edgementioning

confidence: 99%

“…Both empirical and modeling studies have emphasized that the same landscape can be connected or fragmented, depending on the movement range of the actual species (Forman 1995;Ims 1995;With and Crist 1995;With et al 1997;Wiens 1997;Solé and Bascompte 2006). For example, an area with wetland patches in North Carolina was found to be connected for mink (Mustela vison; ) but fragmented for prothonotary dispersal range ≈ 25 km warblers (Prothonotaria citrea; dispersal range mostly !12 km; Bunn et al 2000). By changing the step length in the simulations, we can test whether species with different dispersal ranges experience different geometries.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transition from Connected to Fragmented Vegetation across an Environmental Gradient: Scaling Laws in Ecotone Geometry

Gastner¹,

Oborny²,

Zimmermann³

et al. 2009

The American Naturalist

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. abstract: A change in the environmental conditions across spacefor example, altitude or latitude-can cause significant changes in the density of a vegetation type and, consequently, in spatial connectivity. We use spatially explicit simulations to study the transition from connected to fragmented vegetation. A static (gradient percolation) model is compared to dynamic (gradient contact process) models. Connectivity is characterized from the perspective of various species that use this vegetation type for habitat and differ in dispersal or migration range, that is, "step length" across the landscape. The boundary of connected vegetation delineated by a particular step length is termed the " hull edge." We found that for every step length and for every gradient, the hull edge is a fractal with dimension 7/ 4. The result is the same for different spatial models, suggesting that there are universal laws in ecotone geometry. To demonstrate that the model is applicable to real data, a hull edge of fractal dimension 7/4 is shown on a satellite image of a piñon-juniper woodland on a hillside. We propose to use the hull edge to define the boundary of a vegetation type unambiguously. This offers a new tool for detecting a shift of the boundary due to a climate change.

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Section: An Outlook To the Significance Of Fragmentation At The Edgementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transition from Connected to Fragmented Vegetation across an Environmental Gradient: Scaling Laws in Ecotone Geometry

Gastner¹,

Oborny²,

Zimmermann³

et al. 2009

The American Naturalist

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“…Nevertheless, we believe that this article is a first step toward finding optimal strategies for nature management of metapopulations. The rules of thumb could act as guidelines or null hypotheses that need testing in particular cases and could steer further research, either with different (e.g., using graph and percolation theory; see, e.g., Keitt et al 1997;Bunn et al 2000;Urban and Keitt 2001) or more detailed models or, ideally, with empirical data. To our knowledge, no such model-based null hypotheses were available before.…”

Section: Discussionmentioning

confidence: 99%

Rules of Thumb for Conservation of Metapopulations Based on a Stochastic Winking-Patch Model

[]

Heesterbeek

2001

The American Naturalist

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From a theoretical viewpoint, nature management basically has two options to prolong metapopulation persistence: decreasing local extinction probabilities and increasing colonization probabilities. This article focuses on those options with a stochastic, single-species metapopulation model. We found that for most combinations of local extinction probabilities and colonization probabilities, decreasing the former increases metapopulation extinction time more than does increasing the latter by the same amount. Only for relatively low colonization probabilities is an effort to increase these probabilities more beneficial, but even then, decreasing extinction probabilities does not seem much less effective. Furthermore, we found the following rules of thumb. First, if one focuses on extinction, one should preferably decrease the lowest local extinction probability. Only if the extinction probabilities are (almost) equal should one prioritize decreases in the local extinction probability of the patch with the best direct connections to and from other patches. Second, if one focuses on colonization, one should preferably increase the colonization probability between the patches with the lowest local extinction probability. Only if the local extinction probabilities are (almost) equal should one instead prioritize increases in the highest colonization probability (unless extinction probabilities and colonization probabilities are very low). The rules of thumb have an important common denominator: the local extinction process has a greater bearing on metapopulation extinction time than colonization.Keywords: colonization, extinction, metapopulation, conservation.Ever since Levins (1969Levins ( , 1970 presented his well-known metapopulation model, it has been clear that the key processes in single-species metapopulation dynamics are local extinction and (re)colonization. For nature management of single-species metapopulations, this has the important consequence that attempts to prolong metapopulation * E-mail: r.s.etienne@plant.wag-ur.nl. † E-mail: j.a.p.heesterbeek@plant.wag-ur.nl.Am. Nat. 2001. Vol. 158, pp. 389- persistence can either be directed toward decreasing the probability of local extinction or toward increasing the probability of colonization. The former may be achieved by, for instance, improving habitat quality or size (cf. Klok and de Roos 1998), whereas the latter is often attained by building corridors or stepping stones (Schultz 1998). However, corridors may affect local extinction probability as well, both positively (by the rescue effect; Brown and Kodric-Brown 1977) and negatively (by a leakage or dilution effect; Allen et al. 1992). Likewise, improving habitat quality may have positive and negative effects on the ability to generate colonists or to be colonized (a better-quality patch might attract more immigrants and could produce more colonizers due to higher reproduction [see, e.g., Hanski 1994;Vos et al. 2001], or such a patch might sustain a larger population and thus offer less ince...

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“…Graph theory in particular has been used in different applications of a wide range of fields for that purpose, however not many graph-theoretic approaches to analyse entities within the urban environment are available in the literature, hence the need for further investigation. Some examples should be mentioned though such as, Bafna (2003), Barr and Barnsley (2004), Bunn et al (2000), Krüger (1999), Nardinochi et al (2003), and Steel et al (2003), amongst others.…”

Section: Motivationmentioning

confidence: 99%

A graph-based algorithm to define urban topology from unstructured geospatial data

Almeida

Morley

Dowman

2013

International Journal of Geographical Information Science

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Interpretation and analysis of urban topology are particularly challenging tasks given the complex spatial pattern of the urban elements, and hence their automation is especially needed. In terms of the urban scene meaning, the starting point in this study is unstructured geospatial data, i.e. no prior knowledge of the geospatial entities is assumed. The aim of translating these data into more meaningful homogeneous regions can be achieved by detecting geographic features within the initial random collection of geospatial objects, and then by grouping them according to their spatial arrangement. The techniques applied to achieve this are those of graph theory applied to urban topology analysis within GIS environment. The role of graph theory in such a task and pre-processing of raw geospatial data were object of another previously published paper; this manuscript focuses primarily on the description of the procedure: "containmentfirst search" (CFS) -based on the well known breadth-first search algorithm for graph traversal, CFS analyzes and interprets the geospatial object arrangements in terms of the extension of the standard notion of the topological relation of adjacency to that of containment, what is defined within this research as "polygon-ring containment". LiDAR data were used as an example scenario for development purposes; in order to test the system proposed as a whole, further tests will entail the use of real world LiDAR datasets with different technical characteristics as well as photogrammetric datasets.

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Landscape connectivity: A conservation application of graph theory

Cited by 516 publications

References 27 publications

Transition from Connected to Fragmented Vegetation across an Environmental Gradient: Scaling Laws in Ecotone Geometry

Transition from Connected to Fragmented Vegetation across an Environmental Gradient: Scaling Laws in Ecotone Geometry

Rules of Thumb for Conservation of Metapopulations Based on a Stochastic Winking-Patch Model

A graph-based algorithm to define urban topology from unstructured geospatial data

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