Gap crossing by chipmunks: an experimental test of landscape connectivity

2002 ◽  
Vol 80 (9) ◽  
pp. 1556-1561 ◽  
Author(s):  
Jeff Bowman ◽  
Lenore Fahrig
Keyword(s):  
Functional Connectivity ◽  
Landscape Connectivity ◽  
Empirical Studies ◽  
Agricultural Landscapes ◽  
Landscape Configuration ◽  
Eastern North America ◽  
Tamias Striatus ◽  
Continuous Forest ◽  
Constant Distance ◽  
Homing Experiment

Eastern chipmunks (Tamias striatus) are forest specialists common to eastern North America. Numerous studies suggest that chipmunks require fencerow corridors between woodlots to maintain functional connectivity in agricultural landscapes. We tested this hypothesis by conducting a homing experiment to assess whether chipmunks would cross nonforested gaps of different sizes. Chipmunks in 11 landscapes were translocated a constant distance of 220–250 m across gaps ranging in size from 0 (continuous forest) to 240 m (mostly gap). Logistic regression analysis demonstrated that the probability of an adult chipmunk returning to its home range was not related to the size of the gap that had to be crossed (χ2 = 0.781, n = 60, P = 0.377, ρ2 = 0.011). Chipmunks crossed the entire range of gap sizes and there was no evidence of a threshold in connectivity. These results suggest that forest woodlots may be functionally connected for chipmunks even without fencerow corridors, and that landscape configuration in the study area may not have isolating effects on chipmunk populations. More empirical studies are required to identify whether functional connectivity thresholds are present in mammal populations as theoretical studies suggest.

scholarly journals Small Landscape Elements Double Connectivity in Highly Fragmented Areas of the Brazilian Atlantic Forest

2021 ◽  
Vol 9 ◽  
Author(s):  
Flávia Freire Siqueira ◽  
Dulcineia de Carvalho ◽  
Jonathan Rhodes ◽  
Carla L. Archibald ◽  
Vanessa Leite Rezende ◽  
...  
Keyword(s):  
Atlantic Forest ◽  
Riparian Forest ◽  
Landscape Connectivity ◽  
Agricultural Landscapes ◽  
Landscape Configuration ◽  
Individual Species ◽  
Forest Fragments ◽  
Landscape Elements ◽  
Habitat Patches ◽  
Seed Disperser

The Atlantic Forest in Brazil is a biodiversity hotspot, yet its diverse ecosystems and species are becoming increasingly threatened by habitat loss and extreme habitat fragmentation. Most habitat patches of Atlantic Forest are dispersed across agricultural landscapes (e.g., grazing and cropping) in relatively small and isolated fragments (80% < 50 ha). Forest fragments < 1 ha, scattered trees in pastures, tree lines on trenches and fences, and remnant riparian forest, collectively called here Small Landscape Elements (SLEs), are very common in this context. While these SLEs make up much of the Atlantic Forests footprint, very little is known about their role or impact on the persistence and conservation of species. In this study, we investigate the role of SLEs on landscape configuration, particularly their contribution toward landscape connectivity of individual species and the genetic flow of species between larger forest fragments. We randomly selected 20 buffers of 707 hectares within a 411,670 hectare area of the Atlantic Forest that was completely covered by forest in the past located in the south of Minas Gerais State, Brazil. The forest cover randomly varied between these buffers. We used graph theory to measure landscape connectivity as the probability of connectivity for different disperser movement types between landscape knots (habitat patches). We used three estimated dispersal distances in the models: pollen disperser insect (50 m), low-mobility seed disperser bird (100 m) and high-mobility seed disperser bird (760 m). The SLEs together increased the probability of connection by roughly 50%, for all model dispersers, if compared to a theoretical baseline landscape containing no SLEs. Of all SLEs, riparian forests contribute the most toward enhancing landscape connectivity. In these highly fragmented landscapes, such as the Atlantic Forest (>70%), the position of SLEs within the landscapes was more important than their respective areas for connectivity. Although the landscapes were deeply fragmented, we showed that the presence of SLEs can increase connectivity and reduce further biodiversity loss in the Atlantic Forest.

scholarly journals Using Bayesian Belief Networks to assess the influence of landscape connectivity on ecosystem service trade-offs and synergies in urban landscapes in the UK

2021 ◽  
Author(s):  
James D. Karimi ◽  
Jim A. Harris ◽  
Ron Corstanje
Keyword(s):  
Functional Connectivity ◽  
Ecosystem Service ◽  
Urban Areas ◽  
Landscape Connectivity ◽  
Structural Characteristics ◽  
Bird Species ◽  
Bayesian Belief Networks ◽  
Belief Networks ◽  
Patch Area ◽  
Trade Offs

Abstract Context Landscape connectivity is assumed to influence ecosystem service (ES) trade-offs and synergies. However, empirical studies of the effect of landscape connectivity on ES trade-offs and synergies are limited, especially in urban areas where the interactions between patterns and processes are complex. Objectives The objectives of this study were to use a Bayesian Belief Network approach to (1) assess whether functional connectivity drives ES trade-offs and synergies in urban areas and (2) assess the influence of connectivity on the supply of ESs. Methods We used circuit theory to model urban bird flow of P. major and C. caeruleus at a 2 m spatial resolution in Bedford, Luton and Milton Keynes, UK, and Bayesian Belief Networks (BBNs) to assess the sensitivity of ES trade-offs and synergies model outputs to landscape and patch structural characteristics (patch area, connectivity and bird species abundance). Results We found that functional connectivity was the most influential variable in determining two of three ES trade-offs and synergies. Patch area and connectivity exerted a strong influence on ES trade-offs and synergies. Low patch area and low to moderately low connectivity were associated with high levels of ES trade-offs and synergies. Conclusions This study demonstrates that landscape connectivity is an influential determinant of ES trade-offs and synergies and supports the conviction that larger and better-connected habitat patches increase ES provision. A BBN approach is proposed as a feasible method of ES trade-off and synergy prediction in complex landscapes. Our findings can prove to be informative for urban ES management.

scholarly journals Local GABA concentration is related to network-level resting functional connectivity

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Charlotte J Stagg ◽  
Velicia Bachtiar ◽  
Ugwechi Amadi ◽  
Christel A Gudberg ◽  
Andrei S Ilie ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Resting State ◽  
Primary Motor Cortex ◽  
Empirical Studies ◽  
Network Connectivity ◽  
Resting State Fmri ◽  
Resonance Spectroscopy ◽  
Resting State Networks ◽  
Inhibitory Neurotransmitter ◽  
Motor Network

Anatomically plausible networks of functionally inter-connected regions have been reliably demonstrated at rest, although the neurochemical basis of these ‘resting state networks’ is not well understood. In this study, we combined magnetic resonance spectroscopy (MRS) and resting state fMRI and demonstrated an inverse relationship between levels of the inhibitory neurotransmitter GABA within the primary motor cortex (M1) and the strength of functional connectivity across the resting motor network. This relationship was both neurochemically and anatomically specific. We then went on to show that anodal transcranial direct current stimulation (tDCS), an intervention previously shown to decrease GABA levels within M1, increased resting motor network connectivity. We therefore suggest that network-level functional connectivity within the motor system is related to the degree of inhibition in M1, a major node within the motor network, a finding in line with converging evidence from both simulation and empirical studies.

scholarly journals Is There an Equivalence between Measures of Landscape Structural and Functional Connectivity for Plants in Conservation Assessments of the Cerrado?

Land ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 459
Author(s):  
Thais Martins Issii ◽  
Erico Fernando Lopes Pereira-Silva ◽  
Carlos Tomás López de Pablo ◽  
Rozely Ferreira dos Santos ◽  
Elisa Hardt
Keyword(s):  
Functional Connectivity ◽  
Empirical Data ◽  
Landscape Connectivity ◽  
Structural Connectivity ◽  
Long Distance ◽  
Dispersal Capacity ◽  
Plant Dispersal ◽  
Optimal Resource ◽  
History Of ◽  
Conservation Assessments

Landscape connectivity can be assessed based on the physical connection (structural connectivity) or the maintenance of flow among habitats depending on the species (functional connectivity). The lack of empirical data on the dispersal capacity of species can lead to the use of simple structural measures. Comparisons between these approaches can improve decision-making processes for the conservation or restoration of habitats in fragmented landscapes, such as the Cerrado biome. This study aimed to understand the correspondence between the measures of landscape structural and functional connectivity for Cerrado plants. Three landscapes with cerradão patches in a pasture matrix were selected for the application of these metrics based on the functional connectivity of four profiles of plant dispersal capacity. The results showed divergent interpretations between the measures of landscape structural and functional connectivity, indicating that the assessment of biodiversity conservation and landscape connectivity is dependent on the set of metrics chosen. Structurally, the studied landscapes had the same number of cerradão patches but varied in optimal resource availability, isolation, heterogeneity, and aggregation. Functional connectivity was low for all profiles (based on the integral index of connectivity—IIC) and null for species with a low dispersal capacity (based on the connectance index—CONNECT), indicating that species with a medium- to long-distance dispersal capacity may be less affected by the history of losses and fragmentation of the Cerrado in the pasture matrix. The functional connectivity metrics used allowed a more robust analysis and, apparently, better reflected reality, but the lack of empirical data on dispersal capacity and the difficulty in choosing an indicator organism can limit their use in the management and planning of conservation and restoration areas.

scholarly journals Green Infrastructure Planning in Metropolitan Regions to Improve the Connectivity of Agricultural Landscapes and Food Security

Land ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 414 ◽  
Author(s):  
Carolina Yacamán Ochoa ◽  
Daniel Ferrer Jiménez ◽  
Rafael Mata Olmo
Keyword(s):  
Urban Agriculture ◽  
Land Use Planning ◽  
Green Infrastructure ◽  
Landscape Connectivity ◽  
Agricultural Landscapes ◽  
Positive Contribution ◽  
Urban Resilience ◽  
Open Spaces ◽  
Metropolitan Regions

Green infrastructure (GI), as a concept and as a tool for environmental land-use planning at various scales, has burst onto the academic, political, and policy-making scenes in the last two decades. This tool, associated with strategic planning, offers integrated solutions for improving the ecological connectivity and urban resilience of open spaces, especially those affected by processes of urban sprawl, the abandonment of agriculture, and the territorial fragmentation of habitats and traditional agricultural landscapes. In spite of the advantages of GI, its design and implementation face a range of challenges and limitations. In this context, this paper has two objectives: Firstly, to address a critical review of recent literature on the subject, which, among other things, highlights the lack of references to the role of peri-urban agriculture in GI planning, and the positive contribution made by peri-urban agriculture to the local food supply and other regulatory and cultural services. Secondly, to propose a methodology to contribute to integrating practical GI planning in metropolitan regions to maximize the activation of traditional agricultural landscapes and the improvement of landscape connectivity in metropolitan regions for the reconnection of rural-urban relationships.

scholarly journals Effect of land use, habitat suitability, and hurricanes on the population connectivity of an endemic insular bat

2020 ◽  
Author(s):  
Camilo A. Calderón-Acevedo ◽  
Armando Rodríguez-Durán ◽  
J. Angel Soto-Centeno
Keyword(s):  
Land Use ◽  
Puerto Rico ◽  
Habitat Suitability ◽  
Landscape Connectivity ◽  
Population Connectivity ◽  
Suitable Habitat ◽  
Population Declines ◽  
Forest Patches ◽  
Continuous Forest ◽  
Forested Areas

AbstractHabitat loss and fragmentation are a leading cause of vertebrate population declines and extinction. Urbanization and natural disasters disrupt landscape connectivity, effectively isolating populations and increasing the risk of local extirpation particularly in island systems. Puerto Rico, one of the most isolated islands in the Caribbean, is home to 13 bat species that have been differentially affected by disturbance during the Anthropocene. We used circuit theory to model the landscape connectivity within Puerto Rico with the goal of understanding how fragmentation affects corridors among forested areas. Models combined species occurrences, land use, habitat suitability, and vegetation cover data to examine connectivity in the endemic bat Stenoderma rufum, and also at the bat community level across the island. Urbanization in Puerto Rico affected bat connectivity overall from east to west and underscored protected and rustic areas for the maintenance of forest corridors. Suitable habitat provided a reliable measure of connectivity among potential movement corridors that connected more isolated areas. We found that intense hurricanes can disrupt forest integrity and affect connectivity of suitable habitat. Some of the largest protected areas in the east of Puerto Rico are at an increasing risk of becoming disconnected from more continuous forest patches. The disruption of corridors that maintain connectivity on the island could explain previous findings of the slow post-hurricane population recovery of S. rufum. Given the increasing rate of urbanization, this pattern could also apply to other vertebrates not analyzed in this study. Our findings show the importance of maintaining forest integrity, emphasizing the considerable conservation value of rustic areas for the preservation of local biodiversity.

scholarly journals Reference Site Influences Perceived Species Loss in Shade Coffee, But Assemblages in Fact Depend on Landscape Context

2021 ◽  
Author(s):  
Maria Juliana Bedoya ◽  
Harrison H Jones ◽  
Kristen Malone ◽  
Lyn C Branch
Keyword(s):  
Agricultural Landscapes ◽  
Camera Traps ◽  
Landscape Context ◽  
Forest Fragments ◽  
Shade Coffee ◽  
Coffee Plantations ◽  
Fragmented Forest ◽  
Continuous Forest ◽  
Species Occupancy

Abstract Context: Shade coffee plantations are purported to maintain forest biodiversity in agricultural landscapes. Understanding their conservation importance is hindered, however, by the limited taxa studied and failure to account for the landscape context of plantations and quality of reference sites.Objectives/Research questions: (1) how occupancy of mammals and birds changed from continuous forest to fragmented forest and coffee plantations while statistically controlling for landscape context, and (2) whether mammal and bird communities responded differently to shade coffee with regard to richness and composition.Methods: We used camera traps to sample ground-dwelling birds and medium- and large-bodied mammals (31 and 29 species, respectively) in shade coffee plantations and two types of reference forest (fragmented and continuous) in Colombia’s Western Andes. We used a multi-species occupancy model to correct for detection and to estimate occupancy, richness, and community composition.Results Shade coffee lacked ~50% of the species found in continuous forest, primarily forest-specialist insectivorous birds and forest-specialist and large-bodied mammals, resulting in different species composition between coffee and forest assemblages. Coffee plantation birds were generally a unique subset of disturbance-adapted specialists, whereas mammals in coffee were mostly generalists encountered across land uses. Forest fragments had species richness more similar to shade coffee than to continuous forest. Species sensitive to shade coffee responded negatively to isolation and disturbance at the landscape scale.Conclusions: Studies comparing coffee with relictual forest fragments may overestimate the conservation value of shade coffee. Conservation of biodiversity in shade coffee landscapes will be ineffective unless these efforts are linked to larger landscape-level conservation initiatives.

scholarly journals Implications of Climate-Driven Fallowing for Ecological Connectivity of Species At Risk

2021 ◽  
Author(s):  
Sofie HE McComb ◽  
Claire Powers ◽  
Forrest Melton ◽  
Ashley Larsen
Keyword(s):  
Climate Change ◽  
At Risk ◽  
Agricultural Landscape ◽  
Landscape Connectivity ◽  
Agricultural Landscapes ◽  
Habitat Connectivity ◽  
Management Policy ◽  
Kern County ◽  
Working Landscapes ◽  
Kit Fox

Abstract Context. Climate change and agricultural intensification are modifying the configuration of natural lands within agricultural landscapes, further impacting species’ ability to move freely between remaining natural areas. These working landscapes have inherently high opportunity costs, making the establishment of additional permanent reserves for species movement unlikely. Objectives. Here we explore the potential for opportunistic and dynamic conservation reserves, in the form of temporary fallowed croplands, to increase connectivity in competing land use regions. Methods. We evaluate the potential for fallowed lands to facilitate habitat connectivity for at-risk species in the San Joaquin Valley (SJV), an intensive agricultural landscape in California. We perform landscape connectivity analyses to examine how historic drought-induced fallowing from 2011 to 2017 in the SJV region impacted connectivity within Kern County for the endangered, endemic San Joaquin kit fox (Vulpes macrotis mutica). Results. We found that an increase in temporary fallowing from 2011 to 2015/2017 in Kern County likely increased habitat connectivity for the kit fox. This finding was represented by reductions in average Cost-Weighted Distances (CWD), Effective Resistances, and CWD-to-Least Cost Path Ratios between core habitat areas, indicating that cumulative costs incurred by kit foxes travelling between primary habitats decreased. Conclusions. Our findings highlight that strategic and cooperative, yet temporary, conservation actions have the potential to reduce the conflict between biodiversity preservation and agricultural production in working landscapes while increasing landscape connectivity. Fallowing-based, agri-environmental schemes could help working areas meet statewide groundwater management policy targets while improving species’ mobility in the face of climate change.

scholarly journals Modular origins of high-amplitude cofluctuations in fine-scale functional connectivity dynamics

2021 ◽  
Vol 118 (46) ◽  
pp. e2109380118
Author(s):  
Maria Pope ◽  
Makoto Fukushima ◽  
Richard F. Betzel ◽  
Olaf Sporns
Keyword(s):  
Functional Connectivity ◽  
Functional Neuroimaging ◽  
Empirical Studies ◽  
Structural Connectivity ◽  
Spatial Arrangement ◽  
High Amplitude ◽  
Brain Regions ◽  
Brain Dynamics ◽  
Modular Organization ◽  
Fine Scale

The topology of structural brain networks shapes brain dynamics, including the correlation structure of brain activity (functional connectivity) as estimated from functional neuroimaging data. Empirical studies have shown that functional connectivity fluctuates over time, exhibiting patterns that vary in the spatial arrangement of correlations among segregated functional systems. Recently, an exact decomposition of functional connectivity into frame-wise contributions has revealed fine-scale dynamics that are punctuated by brief and intermittent episodes (events) of high-amplitude cofluctuations involving large sets of brain regions. Their origin is currently unclear. Here, we demonstrate that similar episodes readily appear in silico using computational simulations of whole-brain dynamics. As in empirical data, simulated events contribute disproportionately to long-time functional connectivity, involve recurrence of patterned cofluctuations, and can be clustered into distinct families. Importantly, comparison of event-related patterns of cofluctuations to underlying patterns of structural connectivity reveals that modular organization present in the coupling matrix shapes patterns of event-related cofluctuations. Our work suggests that brief, intermittent events in functional dynamics are partly shaped by modular organization of structural connectivity.

scholarly journals Using Bayesian Belief Networks to assess the influence of landscape connectivity on ecosystem service trade-offs and synergies in urban landscapes in the UK

2021 ◽  
Author(s):  
James Karimi ◽  
Jim A. Harris ◽  
Ron Concorstanje
Keyword(s):  
Functional Connectivity ◽  
Ecosystem Service ◽  
Urban Areas ◽  
Landscape Connectivity ◽  
Structural Characteristics ◽  
Bird Species ◽  
Bayesian Belief Networks ◽  
Belief Networks ◽  
Patch Area ◽  
Trade Offs

Abstract Context Landscape connectivity is assumed to influence ecosystem service (ES) trade-offs and synergies. However, empirical studies of the effect of landscape connectivity on ES trade-offs and synergies are limited, especially in urban areas where the interactions between patterns and processes are complex.Objectives The objectives of this study were to use a Bayesian Belief Network approach to (1) assess whether functional connectivity drives ES trade-offs and synergies in urban areas and (2) assess the influence of connectivity on the supply of ESs.Methods We used circuit theory to model urban bird flow of P. major and C. caeruleus at a 2 m spatial resolution in Bedford, Luton and Milton Keynes, UK, and Bayesian Belief Networks (BBNs) to assess the sensitivity of ES trade-offs and synergies model outputs to landscape and patch structural characteristics (patch area, connectivity and bird species abundance).Results We found that functional connectivity was the most influential variable in determining two of three ES trade-offs and synergies. Patch area and connectivity exerted a strong influence on ES trade-offs and synergies. Low patch area and low to moderately low connectivity were associated with high levels of ES trade-offs and synergies.Conclusions This study demonstrates that landscape connectivity is an influential determinant of ES trade-offs and synergies and supports the conviction that larger and better-connected habitat patches increase ES provision. A BBN approach is proposed as a feasible method of ES trade-off and synergy prediction in complex landscapes. Our findings can prove to be informative for urban ES management.

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