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91.
Heike Kappes Kurt Jordaens Frederik Hendrickx Jean-Pierre Maelfait Luc Lens Thierry Backeljau 《Landscape Ecology》2009,24(5):685-697
Habitat fragmentation is a major cause for species loss, but its effect on invertebrates with low active dispersal power,
like terrestrial gastropods, has rarely been studied. Such species can not cross a hostile habitat matrix, for which the predictions
of island theory, such as positive relations between species richness and patch size, should apply. In order to test this
prediction, we studied gastropod species diversity by assessing gastropod assemblage characteristics from 35 sites in 19 fragments
of deciduous old-growth forests in the Lower Rhine Embayment, Germany. Assemblages differed between larger (≥700 ha) and smaller
forests (<400 ha), those of large forests held a higher percentage of forest species. Although α-diversity was similar between
the two forest size classes, small forests often comprised matrix species, resulting in a higher β-diversity. Edge effects
on the species richness of matrix species were noticeable up to 250 m into the forest. Hierarchical partitioning revealed
that distance to disturbances (external edge, internal edges like roads) explained most assemblage variables, whereas forest
size and woodland cover within a 1 km radius from the sites explained only a few assemblage variables. Densities of two forest-associated
species, Discus rotundatus and Arion fuscus, decreased with forest size. Yet, forest size was positively correlated with richness of typical forest species and densities
of Limax cinereoniger. The latter species seems to need forests of >1,000 ha, i.e., well above the size of most fragments. In conclusion, the prediction
is valid only for forest species. The response to fragmentation is species specific and seems to depend on habitat specialization
and macroclimatic conditions.
Jean-Pierre Maelfait: Deceased. 相似文献
92.
93.
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
94.
The question of what determines plant community composition is fundamental to the study of plant community ecology. We examined
the relative roles of historical land use, landscape context, and the biophysical environment as determinants of plant community
composition in regenerating citrus groves in north-central Florida. Results were interpreted in light of plant functional
traits. Herbaceous and woody plants responded differently to broad-scale variables; herbs correlated most strongly with surrounding
land cover at a scale of 8 km, while the only significant determinant of woody species distributions was local land use history.
There were significant correlations between herbaceous species and spatial context, habitat isolation, environmental variables,
and historical variables. Partial Mantel tests indicated that each variable provided a unique contribution in explaining some
of the variation in the herbaceous dataset. The correlation between woody plants and local historical variables remained significant
even with other effects corrected for. In the herbaceous community, species composition was linked to functional traits much
as expected from classical theory. While spatial influences in our study system are important for both woody and herbaceous
plants, the primary determinant of plant community composition in regenerating citrus groves is historical land use. Our results
suggest that the fine-scale mechanisms of local competition, tolerance and facilitation invoked by many classical studies
may ultimately be less important than land use history in understanding current plant community composition in regenerating
agricultural areas. 相似文献
95.
Tradable biodiversity credit systems provide flexible means to resolve conflicts between development and conservation land-use
options for habitats occupied by threatened or endangered species. We describe an approach to incorporate the influence of
habitat fragmentation into the conservation value of tradable credits. Habitat fragmentation decreases gene flow, increases
rates of genetic drift and inbreeding, and increases probabilities of patch extinction. Importantly, tradable credit systems
will change the level of fragmentation over time for small and/or declining populations. We apply landscape equivalency analysis
(LEA), a generalizable, landscape-scale accounting system that assigns conservation value to habitat patches based on patch
contributions to abundance and genetic variance at landscape scales. By evaluating habitat trades using two models that vary
the relationship between dispersal behaviors and landscape patterns, we show that LEA provides a novel method for limiting
access to habitat at the landscape-scale, recognizing that the appropriate amount of migration needed to supplement patch
recruitment and to offset drift and inbreeding will vary as landscape pattern changes over time. We also found that decisions
based on probabilities of persistence alone would ignore changes in migration, genetic drift, and patch extinction that result
from habitat trades. The general principle of LEA is that habitat patches traded should make at least equivalent contributions
to rates of recruitment and migration estimated at a landscape scale. Traditional approaches for assessing the “take” and
“jeopardy” standards under the Endangered Species Act based on changes in abundance and probability of persistence may be
inadequate to prevent trades that increase fragmentation. 相似文献
96.
97.
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
98.
99.
The discipline of landscape ecology recognizes the importance of measuring habitat suitability variables at spatial scales
relevant to specific organisms. This paper uses a novel multi-scale hierarchical patch delineation method, PatchMorph, to
measure landscape patch characteristics at two distinct spatial scales and statistically relate them to the presence of state-listed
endangered yellow-billed cuckoos (Coccyzus americanus occidentalis) nesting in forest patches along the Sacramento River, California, USA. The landscape patch characteristics calculated were:
patch thickness, area of cottonwood forest, area of riparian scrub, area of other mixed riparian forest, and total patch area.
A third, regional spatial variable, delineating the north and south portions of study area was also analyzed for the effect
of regional processes. Using field surveys, the landscape characteristics were related to patch occupancy by yellow-billed
cuckoos. The area of cottonwood forest measured at the finest spatial scale of patches was found to be the most important
factor determining yellow-billed cuckoo presence in the forest patches, while no patch characteristics at the larger scale
of habitat patches were important. The regional spatial variable was important in two of the three analysis techniques. Model
validation using an independent data set of surveys (conducted 1987–1990) found 76–82% model accuracy for all the statistical
techniques used. Our results show that the spatial scale at which habitat characteristics are measured influences the suitability
of forest patches. This multi-scale patch and model selection approach to habitat suitability analysis can readily be generalized
for use with other organisms and systems. 相似文献
100.
Combining top-down and bottom-up dynamics in land use modeling: exploring the future of abandoned farmlands in Europe with the Dyna-CLUE model 总被引:9,自引:0,他引:9
Land use change is the result of interactions between processes operating at different scales. Simulation models at regional
to global scales are often incapable of including locally determined processes of land use change. This paper introduces a
modeling approach that integrates demand-driven changes in land area with locally determined conversion processes. The model
is illustrated with an application for European land use. Interactions between changing demands for agricultural land and
vegetation processes leading to the re-growth of (semi-) natural vegetation on abandoned farmland are explicitly addressed.
Succession of natural vegetation is simulated based on the spatial variation in biophysical and management related conditions,
while the dynamics of the agricultural area are determined by a global multi-sector model. The results allow an exploration
of the future dynamics of European land use and landscapes. The model approach is similarly suitable for other regions and
processes where large scale processes interact with local dynamics. 相似文献