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121.
Brian R. Miranda Brian R. Sturtevant Jian Yang Eric J. Gustafson 《Landscape Ecology》2009,24(5):587-598
We demonstrate a method to evaluate the degree to which a meta-model approximates spatial disturbance processes represented
by a more detailed model across a range of landscape conditions, using neutral landscapes and equivalence testing. We illustrate
this approach by comparing burn patterns produced by a relatively simple fire spread algorithm with those generated by a more
detailed fire behavior model from which the simpler algorithm was derived. Equivalence testing allows objective comparisons
of the output of simple and complex models, to determine if the results are significantly similar. Neutral landscape models
represent a range of landscape conditions that the model may encounter, allowing evaluation of the sensitivity and behavior
of the model to different landscape compositions and configurations. We first tested the model for universal applicability,
then narrowed the testing to assess the practical domain of applicability. As a whole, the calibrated simple model passed
the test for significant equivalence using the 25% threshold. When applied to a range of landscape conditions different from
the calibration scenarios, the model failed the tests for equivalence. Although our particular model failed the tests, the
neutral landscape models were helpful in determining an appropriate domain of applicability and in assessing the model sensitivity
to landscape changes. Equivalence testing provides an effective method for model comparison, and coupled with neutral landscapes,
our approach provides an objective way to assess the domain of applicability of a spatial model. 相似文献
122.
Maintaining connectivity among local populations in a fragmented landscape is crucial for the survival of many species. For
isolated habitat patches, stochastic fluctuations and reduced gene flow can lead to high risk of extinction. The connectivity
of the landscape is especially crucial for the carabid species living in the fragmented forests of the Bereg plain (NE Hungary
and W Ukraine) because a highway will be constructed through the plain. Our purpose is to (1) evaluate the impacts of three
possible highway tracks, (2) suggest a solution that is realistic with less impact on connectivity than other plans and (3)
discuss how to decrease the disadvantageous effects of each track. Our results, based on a network analysis of landscape graph
of patches and ecological corridors, indicate that the intended highway could have deleterious consequences on forest-living
carabids. Relatively simple actions, like the establishment of stepping stones, could compensate for the loss of habitat connectivity
and promote the survival of carabids, or minor modifications in one possible track could diminish its adverse effects. While
many other studies would be needed for a comprehensive assessment of the biotic impact of the highway, we provide an example
on the usefulness of network analysis for land use management.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
123.
Habitat specificity indices reflect richness (α) and/or distinctiveness (β) components of diversity. The latter may be defined by α and γ (landscape) diversity in two alternative ways: multiplicatively () and additively (). We demonstrate that the original habitat specificity concept of Wagner and Edwards (Landscape Ecol 16:121–131, 2001) consists of three independent components: core habitat specificity (uniqueness of the species composition), patch area and
patch species richness. We describe habitat specificity as a family of indices that may include either area or richness components,
or none or both, and open for use of different types of mean in calculation of core habitat specificity. Core habitat specificity
is a beta diversity measure: the effective number of completely distinct communities in the landscape. Habitat specificity
weighted by species number is a gamma diversity measure: the effective number of species that a patch contributes to landscape
richness. We compared 12 habitat specificity indices by theoretical reasoning and by use of field data (vascular plant species
in SE Norwegian agricultural landscapes). Habitat specificity indices are strongly influenced by weights for patch area and
patch species richness, and the relative contribution of rare vs. common species (type of mean). The relevance of properties
emphasized by each habitat specificity index for evaluation of patches in a biodiversity context is discussed. Core habitat
specificity is emphasized as an ecologically interpretable measure that specifically addresses patch uniqueness while habitat
specificity weighted by species number combines species richness and species composition in ways relevant for conservation
biological assessment.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
124.
Paul C. Stoy Mathew Williams Mathias Disney Ana Prieto-Blanco Brian Huntley Robert Baxter Philip Lewis 《Landscape Ecology》2009,24(7):971-986
Transferring ecological information across scale often involves spatial aggregation, which alters information content and
may bias estimates if the scaling process is nonlinear. Here, a potential solution, the preservation of the information content
of fine-scale measurements, is highlighted using modeled net ecosystem exchange (NEE) of an Arctic tundra landscape as an
example. The variance of aggregated normalized difference vegetation index (NDVI), measured from an airborne platform, decreased
linearly with log(scale), resulting in a linear relationship between log(scale) and the scale-wise modeled NEE estimate. Preserving
three units of information, the mean, variance and skewness of fine-scale NDVI observations, resulted in upscaled NEE estimates
that deviated less than 4% from the fine-scale estimate. Preserving only the mean and variance resulted in nearly 23% NEE
bias, and preserving only the mean resulted in larger error and a change in sign from CO2 sink to source. Compressing NDVI maps by 70–75% using wavelet thresholding with the Haar and Coiflet basis functions resulted
in 13% NEE bias across the study domain. Applying unique scale-dependent transfer functions between NDVI and leaf area index
(LAI) decreased, but did not remove, bias in modeled flux in a smaller expanse using handheld NDVI observations. Quantifying
the parameters of statistical distributions to preserve ecological information reduces bias when upscaling and makes possible
spatial data assimilation to further reduce errors in estimates of ecological processes across scale. 相似文献
125.
126.
The viability of metapopulations in fragmented landscapes has become a central theme in conservation biology. Landscape fragmentation
is increasingly recognized as a dynamical process: in many situations, the quality of local habitats must be expected to undergo
continual changes. Here we assess the implications of such recurrent local disturbances for the equilibrium density of metapopulations.
Using a spatially explicit lattice model in which the considered metapopulation as well as the underlying landscape pattern
change dynamically, we show that equilibrium metapopulation density is maximized at intermediate frequencies of local landscape
disturbance. On both sides around this maximum, the metapopulation may go extinct. We show how the position and shape of the
intermediate viability maximum is responding to changes in the landscape’s overall habitat quality and the population’s propensity
for local extinction. We interpret our findings in terms of a dual effect of intensified landscape disturbances, which on
the one hand exterminate local populations and on the other hand enhance a metapopulation’s capacity for spreading between
habitat clusters. 相似文献
127.
Confronting collinearity: comparing methods for disentangling the effects of habitat loss and fragmentation 总被引:1,自引:1,他引:0
Adam C. Smith Nicola Koper Charles M. Francis Lenore Fahrig 《Landscape Ecology》2009,24(10):1271-1285
Estimating the relative importance of habitat loss and fragmentation is necessary to estimate the potential benefits of specific
management actions and to ensure that limited conservation resources are used efficiently. However, estimating relative effects
is complicated because the two processes are highly correlated. Previous studies have used a wide variety of statistical methods
to separate their effects and we speculated that the published results may have been influenced by the methods used. We used
simulations to determine whether, under identical conditions, the following 7 methods generate different estimates of relative
importance for realistically correlated landscape predictors: residual regression, model or variable selection, averaged coefficients
from all supported models, summed Akaike weights, classical variance partitioning, hierarchical variance partitioning, and
a multiple regression model with no adjustments for collinearity. We found that different methods generated different rankings
of the predictors and that some metrics were strongly biased. Residual regression and variance partitioning were highly biased
by correlations among predictors and the bias depended on the direction of a predictor’s effect (positive vs. negative). Our
results suggest that many efforts to deal with the correlation between amount and fragmentation may have done more harm than
good. If confounding effects are controlled and adequate thought is given to the ecological mechanisms behind modeled predictors,
then standardized partial regression coefficients are unbiased estimates of the relative importance of amount and fragmentation,
even when predictors are highly correlated. 相似文献
128.
Robert A. Mccleery 《Landscape Ecology》2009,24(4):483-493
Predator stimuli created by humans in the urban environment may alter animals’ anti-predator behaviors. I hypothesized that
habituation would cause anti-predator behaviors to decrease in urban settings in response to humans. Additionally, I hypothesized
that populations habituated to humans would show reduced responses to other predator stimuli. I observed three populations
of squirrels (urban, suburban and rural) responses to human approaches, red-tailed hawk vocalizations (Buteo jamaicensis) and coyote (Canis latrans) vocalizations. Mahalanobis distances of anti-predator behaviors in response to human approaches were consistent with the
urban–rural gradient. Flight initiation distances (X
2 = 26.33, df = 2, P < 0.001) and amount of time dedicated to anti-predator behavior (X
2 = 10.94, df = 2, P = 0.004) in response to human approaches were also consistent with the urban–rural gradient. Supporting the habituation hypothesis,
naive juvenile squirrels increased flight initiation distances (X
2 = 35.89, df = 1, P < 0.001) and time dedicated to anti-predator behaviors (X
2 = 9.46, df = 1, P = 0.002) relative to adult squirrels in the same urban environment. Time dedicated to anti-predator behaviors differed among
all three sites in response to both coyote (X
2 = 9.83, df = 2, P = 0.007) and hawk (X
2 = 6.50, df = 2, P = 0.035) vocalizations. Responses to both vocalizations on rural sites (coyote = 45%, hawk = 55%) greater than twice that
found on the urban sites (coyote = 11%, hawk = 20%). This is possibly the first case of a transfer of habituation demonstrated
under field conditions. 相似文献
129.
The ecology and culture of landscape sustainability: emerging knowledge and innovation in landscape research and practice 总被引:4,自引:1,他引:3
Laura R. Musacchio 《Landscape Ecology》2009,24(8):989-992
Landscape researchers and practitioners, using the lens of sustainability science, are breaking new ground about how people’s
behaviors and actions influence the structure, function, and change of designed landscapes in an urbanizing world. The phrase—the
scientific basis of the design for landscape sustainability—is used to describe how sustainability science can contribute
to translational landscape research and practice about the systemic relationships among landscape sustainability, people’s
contact with nature, and complex place-based problems. In the first section of this article, important definitions about the
scientific basis of the design for landscape sustainability are reviewed including the six Es of landscape sustainability—environment, economic, equity, aesthetics, experience, and ethics. A conceptual framework about the six Es of landscape sustainability for designed landscapes is introduced. The interrelatedness,
opportunities, contradictions, and limitations of the conceptual framework are discussed in relation to human health/security,
ecosystem services, biodiversity, and resource management. The conceptual framework about the six Es of landscape sustainability
for designed landscapes follows the tradition in which landscape researchers and practitioners synthesize emerging trends
into conceptual frameworks for advancing basic and applied activities. 相似文献
130.