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Applied ecology could benefit from new tools that identify potential movement pathways of invasive species, particularly where
data are sparse. Cost surface analysis (CSA) estimates the permeability (friction) across a landscape and can be applied to
dispersal modelling. Increasingly used in a diversity of applications, several fundamental assumptions that might influence
the outputs of CSA (cost surfaces and least-cost pathways) have yet to be systematically examined. Thus, we explore two issues:
the presumed relationship between habitat preferences and dispersal behaviour as well as the degree of landscape fragmentation
through which an organism moves by modelling a total of 18 sensitivity and dispersal scenarios. We explored the effect of
fragmentation by altering the friction values (generally assigned using expert opinion) associated with patch and linear features.
We compared these sensitivity scenarios in two sites that differed in fragmentation. We also used eastern grey squirrels (Sciurus carolinensis) as an example invading species and compared diffusion models and two contrasting cost surface dispersal scenarios. The diffusion
model underestimated spread because squirrels did not move randomly through the landscape. Despite contrasting assumptions
regarding dispersal behaviour, the two cost surfaces were strikingly similar while the least-cost paths differed. Furthermore,
while the cost surfaces were insensitive to changes in friction values for linear features, they were sensitive to assumptions
made for patch features. Our results suggest that movement in fragmented landscapes may be more sensitive to assumptions regarding
friction values than contiguous landscapes. Thus, the reliability of CSA may depend not only on the range of friction values
used for patches but also the degree of contiguity in the landscape. 相似文献
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Nicholas C. Coops Steve N. Gillanders Michael A. Wulder Sarah E. Gergel Trisalyn Nelson Nicholas R. Goodwin 《Forest Ecology and Management》2010
The current epidemic of mountain pine beetle (Dendroctonus ponderosae Hopkins) in British Columbia, Canada, has impacted an area of over 13 million hectares presenting a considerable challenge to provincial forest resource managers. Remote sensing technologies offer a highly effective tool to monitor this impact due to very large areas involved and its ability to detect dead and dying tree crowns. Conventionally, change detection procedures based upon spectral values have been applied; however, analysis of landscape pattern changes associated with long-time series change detection approaches present opportunities for the generation of unique and ecologically important information. This study is focussed on the detection and monitoring of the shape and area characteristics of lodgepole pine stands during mountain pine beetle infestation to quantify the progression of forest fragmentation and related loss of landscape connectivity. A set of landscape pattern indices were applied to a set of images consisting of six Landsat satellite images spanning the period from 1993 to 2006. Our results indicate that the impacts of the mountain pine beetle infestation on forest spatial pattern consist of an increase in the number of patches, an increase in forest patch shape complexity, a reduction in forest patch size, an increase in forest patch isolation, and a decrease in interspersion. These findings demonstrate the unique information available from long-time series satellite imagery combined with pattern analysis to better understand the combined effects of insect infestation and forest salvage and harvesting. 相似文献
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Baudron Frédéric Schultner Jannik Duriaux Jean-Yves Gergel Sarah E. Sunderland Terry 《Landscape Ecology》2019,34(2):341-356
Landscape Ecology - It remains unclear how agricultural landscapes can best serve multiple purposes such as simultaneously maintaining agricultural productivity and conserving biodiversity. Our... 相似文献
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Xuan Guo Nicholas C. Coops Sarah E. Gergel Christopher W. Bater Scott E. Nielsen J. John Stadt Mark Drever 《Landscape Ecology》2018,33(3):491-511
Context
The application of regional-level airborne lidar (light detection and ranging) data to characterize habitat patches and model habitat connectivity over large landscapes has not been well explored. Maintaining a connected network of habitat in the presence of anthropogenic disturbances is essential for regional-level conservation planning and the maintenance of biodiversity values.Objectives
We quantified variation in connectivity following simulated changes in land cover and contrasted outcomes when different conservation priorities were emphasized.Methods
First, we defined habitat patches using vegetation structural attributes identified via lidar. Second, habitat networks were constructed for different forest types and assessed using network connectivity metrics. And finally, land cover change scenarios were simulated using a series of habitat patch removals, representing the impact of implementing different spatial prioritization schemes.Results
Networks for different forest structure types produced very different patch distributions. Conservation scenarios based on different schemes led to contrasting changes during land cover change simulations: the scheme prioritizing only habitat area resulted in immediate near-term losses in connectivity, whereas the scheme considering both habitat area and their spatial configurations maintained the overall connectivity most effectively. Adding climate constraints did not diminish or improve overall connectivity.Conclusions
Both habitat area and habitat configuration should be considered in dynamic modeling of habitat connectivity under changing landscapes. This research provides a framework for integrating forest structure and cover attributes obtained from remote sensing data into network connectivity modeling, and may serve as a prototype for multi-criteria forest management and conservation planning.6.
Thresholds in seascape connectivity: influence of mobility, habitat distribution, and current strength on fish movement 总被引：1，自引：0，他引：1
Assessing connectivity of the marine environment is a fundamental challenge for marine conservation and planning, yet conceptual development in habitat connectivity has been based on terrestrial examples rather than marine ecosystems. Here, we explore differences in marine environments that could affect localized movement of marine organisms and demonstrate the importance of incorporating them into seascape models. We link a fish-based cost surface model to simulated seascapes to test hypotheses about the effects of fish mobility, water current strength, and their interactions on functional connectivity of a seascape. Our models predict that sedentary fish should be more sensitive to habitat change than more mobile fish. Furthermore, highly mobile fish should be more sensitive to water currents than habitat change. In our models, the cost of swimming against a current (of any strength) exceeded its benefits, resulting in overall decreases in connectivity with increasing current strengths. We further hypothesized that thresholds in functional connectivity will be affected by both fish mobility and water current strength. Connectivity thresholds in the models occurred when 10–50 % of benthic habitat was favourable; below these thresholds there was a rapid increase in path cost. Thresholds were influenced by the interaction of relative habitat costs (simulated fish mobility) and habitat fragmentation: thresholds for less mobile fish (higher relative cost) were reached at lower habitat abundance when habitat was fragmented, while thresholds for mobile fish were less affected by fragmentation. Our approach suggests mobility and water current are useful indicators of connectivity in marine environments and should be incorporated in seascape models. 相似文献
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Paulo G. Molin Sarah E. Gergel Britaldo S. Soares-Filho Silvio F. B. Ferraz 《Landscape Ecology》2017,32(4):857-870
Context
Despite continued forest cover losses in many parts of the world, Atlantic Forest, one of the largest of the Americas, is increasing in some locations. Economic factors are suggested as causes of forest gain, while enforcement has reduced deforestation.Objectives
We examine three aspects of this issue: the relative importance of biophysical versus anthropogenic factors in driving forest dynamics; role of forest mean patch age influencing areas targeted for losses; and what future forest mean patch age mosaic we can expect (more forest cover and full forest maturity?).Methods
Three land cover maps from 1990, 2000 and 2010, were used in the study. We selected six biophysical and six anthropogenic spatial determinants to analyze by means of weights of evidence, using Dinamica software.Results
Results show that forest regrowth is influenced by multiple factors, working in synergy. Biophysical variables are related to forest gain while anthropogenic are associated with loss. Clear patterns of regrowth on pasture and sugarcane plantations occurred, especially near rivers and forest patches, on steeper slopes and with sufficient rainfall. Forest loss has targeted both older and newer forests. Future projections reveal forest gain in a slow pace, followed by specific ecosystem service losses, due to continuous trends of older mature forest loss.Conclusions
Regrowth is linked to land abandonment, and to neighboring environmental conditions. It is important to question which mechanisms will guarantee and potentiate new regrowth, thus contributing to landscape restoration and reestablishment of ecosystem services in the Atlantic Forest.8.
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Protection of rare ecosystems requires information on their abundance and spatial distribution, yet mapping rare ecosystems,
particularly those which are fragmented, is a challenge. Use of high spatial resolution satellite imagery is increasing, in
part because it may be well-suited for mapping fine-scale components of landscapes. We classified high spatial resolution
QuickBird imagery of coastal British Columbia, Canada into late seral forest associations. With an emphasis on rare forest
associations, we compared the classification accuracies resulting from contrasting accuracy assessment techniques. We also
evaluated the impact of post-classification image smoothing on the quantity and configuration of rare forest associations
mapped. Less common associations were generally classified with lower accuracies than more abundant associations, however,
accuracies varied depending on the assessment technique used. In particular, ignoring the presence of fine-scale heterogeneity
falsely lowered the estimates of map accuracy by approximately 20%. Smoothing, while generally increasing the accuracies of
rare forest associations, had a large effect on their predicted spatial extent and configuration. Simply due to smoothing,
areal estimates of rare associations differed by as much as 36%, the number of patches decreased by 73% on average, and mean
patch size increased by up to 650%. Our findings indicate that routinely used post-classification and map assessment techniques
can greatly impact the portrayal of rare and fragmented ecosystems. Further research is needed on the specific challenges
of mapping and assessing the accuracy of rare ecosystems in fragmented and heterogeneous landscapes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献