The challenge of assaying landscape connectivity in a changing world: A 27-year case study in the southern Great Plains (USA) playa network

McIntyre, Nancy E.; Collins, Steven; Starr, Scott M.; Gestel, Natasja van

doi:10.1016/j.ecolind.2018.04.051

Cited by 20 publications

(14 citation statements)

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“…We calculated average nodal connectance (average number of connections that each node has with other nodes, with lower values indicating remnants that are more isolated), graph diameter (longest most-direct path between the farthest two connected nodes, indicating the distance of the most efficient dispersal route through the network, moving from remnant to remnant), and transitivity (a unitless clustering coefficient that ranges from 0 to 1, with higher values indicating that most remnants are within the coalescence distance of at least two other remnants). See Csardi and Nepusz 72 for more information on how each of these metrics is calculated and McIntyre et al 41 for ecological interpretation of these metrics. We were able to run the analyses for remnants ≥ 3 ha using package igraph 72 in RStudio on a Microsoft Azure virtual machine that was optimized to memory size of 20 vCPUs, 160 Gb RAM, 32 data disks, 32,000 Max IOPS, and 750 Gb temporary storage.…”

Section: Methodsmentioning

confidence: 99%

“…This approach allows for identification of nodes that are crucial in supporting overall network cohesion; because identification of priority sites is a key goal of conservation, graph theory is an important rapid-assessment tool 37 , 39 . In this approach, the overall network of remnants can be quantified by metrics that assess node density, path redundancy, and network resilience 40 , 41 . In addition, the roles of individual forest remnants in facilitating connectivity through the network can be determined 42 , 38 .…”

Section: Introductionmentioning

confidence: 99%

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Identifying structural connectivity priorities in eastern Paraguay’s fragmented Atlantic Forest

Sancha

Boyle

McIntyre

2021

Sci Rep

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The Atlantic Forest of eastern Paraguay has experienced extensive recent deforestation. Less than one-third of the region is forested, and the remaining forest largely consists of isolated remnants with potentially disrupted connectivity for forest fauna. We used a graph theory approach to identify those forest remnants that are important in maintaining landscape structural connectivity for mammals in this fragmented forest. We quantified structural connectivity for forest remnants over the period 2000–2019 at three levels: the entire network of Atlantic Forest remnants in eastern Paraguay; at 10 smaller, nested spatial scales (40–10,000 m) encompassing a range of potential mammalian dispersal abilities; and at the level of individual remnants. We used 10 graph theory metrics to assess aspects of network complexity, dispersal-route efficiency, and individual remnant importance in supporting structural connectivity. We identified forest remnants that serve as important structural connectivity roles as stepping stones, hubs, or articulation points and that should be prioritized for connectivity conservation. Structural connectivity was constrained for organisms incapable of travelling at least 9–12 km (farthest distances between nearest-neighboring forest remnants depending on whether smaller remnants were included or not) and was particularly limited for area-sensitive forest-specialist mammals. With the increased forest loss and fragmentation that is occurring, the connectivity of this system will likely be further compromised, but most of the remnants that we identified as playing important roles for structural connectivity were outside of the country’s proposed “green corridor,” indicating additional areas where conservation action can be directed.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Identifying structural connectivity priorities in eastern Paraguay’s fragmented Atlantic Forest

Sancha

Boyle

McIntyre

2021

Sci Rep

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“…Interestingly, they provided the first and so far, the only evidence that past connectivity (1962 and/or 1981) and/or the successive temporal changes in connectivity (1962-1981 and/or 1981-2000) explain the current diversity patterns of trees, frogs and birds. Similar approaches were applied by Hernández et al (2015), McIntyre et al (2018) and Saura et al (2019), who used variations in global and/or local spatial connectivity over several time steps to assess temporal changes in the spatial connectivity of forest, aquatic habitats and protected areas over long time periods (1975-2011, 1945-2000s and 2010-2018) By contrast, several studies tested for significant differences in local or global connectivity between time steps in the time series. These differences were assessed by comparing the standard error (Rayfield et al 2008;Raatikainen et al 2018) To go further, especially if many time steps are involved, it is possible to use statistical modelling to identify the sign and the magnitude of the overall trend of connectivity values, while accounting for the variability of connectivity values occurring over the period concerned.…”

Section: Assessment Of Variations In Spatial Connectivity Valuesmentioning

confidence: 99%

“…, respectively McIntyre et al (2018). averaged connectivity values obtained from numerous short time steps (e.g., intra-decadal) to a few long time steps (e.g., inter-decadal).…”

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confidence: 99%

How to assess the temporal dynamics of landscape connectivity in ever-changing landscapes: a literature review

et al. 2021

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Context. Landscape connectivity plays a key role in determining the persistence of species inhabiting fragmented habitat patches. In dynamic landscapes, most studies measure connectivity at multiple time steps, but pay less attention to explicitly quantifying its temporal dynamics to gain insights into its role in biodiversity patterns, thereby enabling more effective operational outcomes.Objectives. This article aimed at making an overview of the existing methods for the assessment of the temporal dynamics of connectivity. By analysing their differences and possible applications, we aimed to highlight knowledge gap and future research directions.Methods. We conducted a systematic review of literature dealing with the assessment of the temporal dynamics of connectivity and obtained 32 studies.Results. We presented two main approaches based on graph theory and compared them from conceptual and operational perspectives. The first widely used approach, accounting only for the spatial dispersal of organisms, quantifies temporal changes in spatial connectivity. Based on two or multiple time steps in the time series, this approach enables assessment of the sense and magnitude of the temporal changes in spatial connectivity. The second recently developed approach quantifies spatio-temporal connectivity, thus accounting for both spatial and temporal dispersal. So far, this holistic assessment of spatio-temporal connectivity only covers two time steps. Conclusion. Existing methods for the assessment of the temporal dynamics of connectivity provideindicators to advance our understanding of biodiversity patterns, and to be able to implement measures to conserve and restore connectivity. We propose future directions to develop these methods.

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“…As the primary source of aboveground freshwater in an otherwise semi-arid region, playas are foci for biodiversity [ 13 , 14 ]. These wetlands are primarily fed via surface runoff from seasonal (June–September) precipitation [ 15 ] and are dry more often than they are wet [ 16 , 17 ]. As depressional wetlands, playas are highly influenced by land use/land cover in their surrounding watersheds and precipitation availability, which jointly affect the amount of runoff reaching a playa [ 18 , 19 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

Urban Areas Create Refugia for Odonates in a Semi-Arid Region

Husband

McIntyre

2021

Insects

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In western Texas, most wetlands are fed from precipitation runoff, making them sensitive to drought regimes, anthropogenic land-use activities in their surrounding watersheds, and the interactive effect between these two factors. We surveyed adult odonates in 133 wetlands (49 in grassland settings, 56 in cropland, and 28 in urban areas) in western Texas from 2003–2020; 33 species were recorded. Most species were widespread generalists, but urban wetlands had the highest species richness, as well as the most unique species of any of the three wetland types. Non-metric, multidimensional scaling ordination revealed that the odonate community in urban wetlands was distinctly different in composition than the odonates in non-urban wetlands. Urban wetlands were smaller in surface area than the other wetland types, but because they were fed from more consistently available urban runoff rather than seasonal precipitation, they had longer hydroperiods, particularly during a multi-year drought when wetlands in other land-cover contexts were dry. This anthropogenically enhanced water supply was associated with higher odonate richness despite presumably impaired water quality, indicating that consistent and prolonged presence of water in this semi-arid region was more important than the presence of native land cover within which the wetland existed. Compared to wetlands in the regional grassland landscape matrix, wetlands in agricultural and urban areas differed in hydroperiod, and presumably also in water quality; these effects translated to differences in the regional odonate assemblage by surrounding land-use type, with the highest richness at urban playas. Odonates in human environments may thus benefit through the creation of a more reliably available wetland habitat in an otherwise dry region.

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The challenge of assaying landscape connectivity in a changing world: A 27-year case study in the southern Great Plains (USA) playa network

Cited by 20 publications

References 57 publications

Identifying structural connectivity priorities in eastern Paraguay’s fragmented Atlantic Forest

Identifying structural connectivity priorities in eastern Paraguay’s fragmented Atlantic Forest

How to assess the temporal dynamics of landscape connectivity in ever-changing landscapes: a literature review

Urban Areas Create Refugia for Odonates in a Semi-Arid Region

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