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1.
Effects of changing spatial scale on the analysis of landscape pattern 总被引：68，自引：6，他引：62
Monica G. Turner Robert V. O'Neill Robert H. Gardner Bruce T. Milne 《Landscape Ecology》1989,3(3-4):153-162
The purpose of this study was to observe the effects of changing the grain (the first level of spatial resolution possible with a given data set) and extent (the total area of the study) of landscape data on observed spatial patterns and to identify some general rules for comparing measures obtained at different scales. Simple random maps, maps with contagion (i.e., clusters of the same land cover type), and actual landscape data from USGS land use (LUDA) data maps were used in the analyses. Landscape patterns were compared using indices measuring diversity (H), dominance (D) and contagion (C). Rare land cover types were lost as grain became coarser. This loss could be predicted analytically for random maps with two land cover types, and it was observed in actual landscapes as grain was increased experimentally. However, the rate of loss was influenced by the spatial pattern. Land cover types that were clumped disappeared slowly or were retained with increasing grain, whereas cover types that were dispersed were lost rapidly. The diversity index decreased linearly with increasing grain size, but dominance and contagion did not show a linear relationship. The indices D and C increased with increasing extent, but H exhibited a variable response. The indices were sensitive to the number (m) of cover types observed in the data set and the fraction of the landscape occupied by each cover type (P
k); both m and P
kvaried with grain and extent. Qualitative and quantitative changes in measurements across spatial scales will differ depending on how scale is defined. Characterizing the relationships between ecological measurements and the grain or extent of the data may make it possible to predict or correct for the loss of information with changes in spatial scale. 相似文献
2.
Characterizing watershed-delineated landscapes in Pennsylvania using conditional entropy profiles 总被引：2，自引：0，他引：2
Johnson Glen D. Myers Wayne L. Patil Ganapati P. Taillie Charles 《Landscape Ecology》2001,16(7):597-610
When the objective is to characterize landscapes with respect to relative degree and type of forest (or other critical habitat) fragmentation, it is difficult to decide which variables to measure and what type of discriminatory analysis to apply. It is also desirable to incorporate multiple measurement scales. In response, a new method has been developed that responds to changes in both the marginal and spatial distributions of land cover in a raster map. Multiscale features of the map are captured in a sequence of successively coarsened resolutions based on the random filter for degrading raster map resolutions. Basically, the entropy of spatial pattern associated with a particular pixel resolution is calculated, conditional on the pattern of the next coarser parent resolution. When the entropy is plotted as a function of changing resolution, we obtain a simple two-dimensional graph called a conditional entropy profile, thus providing a graphical visualization of multi-scale fragmentation patterns.Using eight-category raster maps derived from 30-meter resolution LANDSAT Thematic Mapper images, the conditional entropy profile was obtained for each of 102 watersheds covering the state of Pennsylvania (USA). A suite of more conventional single-resolution landscape measurements was also obtained for each watershed using the FRAGSTATS program. After dividing the watersheds into three major physiographic provinces, cluster analysis was performed within each province using various combinations of the FRAGSTATS variables, land cover proportions and variables describing the conditional entropy profiles. Measurements of both spatial pattern and marginal land cover proportions were necessary to clearly discriminate the watersheds into distinct clusters for most of the state; however, the Piedmont province essentially only required the land cover proportions. In addition to land cover proportions, only the variables describing a conditional entropy profile appeared to be necessary for the Ridge and Valley province, whereas only the FRAGSTATS variables appeared to be necessary for the Appalachian Plateaus province. Meanwhile, the graphical representation of conditional entropy profiles provided a visualization of multi-scale fragmentation that was quite sensitive to changing pattern. 相似文献
3.
Group selection silviculture creates canopy openings that can alter connectivity in patchy forests, thereby affecting wildlife
movement and fire behavior. We examined effects of group selection silviculture on percolation (presence of continuously forested
routes across a landscape) in Sierra Nevada East-side pine forest in northern California, USA. Four ~ 250 ha project areas
were analyzed at three map resolutions in three ways: analyzing forest cover maps for percolation before and after group-selection
treatment, placing simulated group openings in forest cover maps until fragmentation occurred, and comparing project areas
to neutral maps that varied in forest cover and self-adjacency. Two project areas were fragmented (i.e., did not percolate)
prior to treatment, one resisted fragmentation, and the other became fragmented by treatment when analyzed at 30 m cell resolution.
Median simulated openings required to create fragmentation agreed well with the actual number. There was a well-defined transition
between percolating and non-percolating neutral maps; increased aggregation of forest lowered the critical value at which
forests percolated. A logistic model based on these maps predicted percolation behavior of the project areas effectively,
but alternative generating algorithms gave slightly different predictions. A graph of this model provides a straightforward
way to visualize how close a landscape is to fragmentation based on its forest cover and aggregation. In East-side Sierran
landscape, fragmentation from group-selection openings may make the landscape less hospitable to the American marten but more
resistant to crown fire. 相似文献
4.
Many landscape indexes with ecological relevance have been proposed, including diversity indexes, dominance, fractal dimension, and patch size distribution. Classified land cover data in a geographic information system (GIS) are frequently used to calculate these indexes. However, a lack of methods for quantifying uncertainty in these measures makes it difficult to test hypothesized relations among landscape indexes and ecological processes. One source of uncertainty in landscape indexes is classification error in land cover data, which can be reported in the form of an error matrix. Some researchers have used error matrices to adjust extent estimates derived from classified land cover data. Because landscape diversity indexes depend only on landscape composition – the extent of each cover in a landscape – adjusted extent estimates may be used to calculate diversity indexes. We used a bootstrap procedure to extend this approach and generate confidence intervals for diversity indexes. Bootstrapping is a technique that allows one to estimate sample variability by resampling from the empirical probability distribution defined by a single sample. Using the empirical distribution defined by an error matrix, we generated a bootstrap sample of error matrixes. The sample of error matrixes was used to generate a sample of adjusted diversity indexes from which estimated confidence intervals for the diversity indexes were calculated. We also note that present methods for accuracy assessment are not sufficient for quantifying the uncertainty in landscape indexes that are sensitive to the size, shape, and spatial arrangement of patches. More information about the spatial structure of error is needed to calculate uncertainty for these indexes. Alternative approaches should be considered, including combining traditional accuracy assessments with other probability data generated during the classification procedure. 相似文献
5.
Increasing land ownership fragmentation in the United States is causing concerns with respect to its ecological implications
for forested landscapes. This is especially relevant given that human influence is one of the most significant driving forces
affecting the forest landscape. A method for generating realistic land ownership maps is needed to evaluate the effects of
ownership fragmentation on forest landscapes in combination with other natural processes captured in forest process models.
Ownership patterns from human activities usually generate landscape boundary shapes different from those arising from natural
processes. Spatial characteristics among ownership types – e.g., private, public ownership – may also differ. To address these
issues, we developed the Fragmented Land Ownership Spatial Simulator (FLOSS) to generate ownership patterns that reflect the
Public Land Survey System (PLSS) shapes and various patch size distributions among different types of ownership (e.g., private,
public). To evaluate FLOSS performance, we compared the simulated patterns with various ownership fragmentation levels to
the actual ownership patterns in the Missouri Ozarks by using selected landscape indices. FLOSS generated landscapes with
spatial characteristics similar to actual landscapes, suggesting that it can simulate different levels of ownership fragmentation.
This will allow FLOSS to serve as a feasible tool for evaluating forest management applications by spatially allocating various
management scenarios in a realistic way. The potentials and limitations of FLOSS application are discussed. 相似文献
6.
Zhai Ruiting Li Weidong Zhang Chuanrong Zhang Weixing Wang Wenjie 《Landscape Ecology》2019,34(9):2103-2121
Context
Landscape metrics play an important role in measurement, analysis, and interpretation of spatial patterns of landscapes. There are a variety of different landscape metrics widely used in landscape ecology. However, existing landscape metrics are mostly non-graphic and single-value indices, which may not be sufficient to describe the complex spatial correlation and interclass relationships of various landscapes. As a transition probability diagram over the lag distance, the transiogram, which emerged in recent years, essentially provides a new graphic metric for measuring and visualizing the auto and cross correlations of landscape categories.
ObjectivesTo explore the capability of the transiogram for measuring spatial patterns of categorical landscape maps and compare it with existing landscape metrics.
MethodsSixteen commonly-used landscape metrics and transiograms (including auto- and cross-transiograms) were estimated and compared for land cover/use classes in four areas with different landscapes.
ResultsResults show that (1) these transiograms can provide visual information about the proportions, aggregation levels, interclass adjacencies, and intra-class/interclass correlation ranges of landscape classes; (2) sills and auto-correlation ranges of transiograms are correlated with the values of some landscape metrics; and (3) the peak height ratios of idealized transiograms can effectively represent the juxtaposition strength of neighboring class pairs.
ConclusionsThe transiogram can be an effective graphic metric for characterizing the auto-correlation of single classes (through auto-transiograms) and the complex interclass relationships, such as interdependency and juxtaposition, between different landscape classes (through cross-transiograms).
相似文献7.
The landscape matrix modifies the effect of habitat fragmentation in grassland butterflies 总被引：1，自引：0，他引：1
Erik ?ckinger Karl-Olof Bergman Markus Franzén Tomá? Kadlec Jochen Krauss Mikko Kuussaari Juha P?yry Henrik G. Smith Ingolf Steffan-Dewenter Riccardo Bommarco 《Landscape Ecology》2012,27(1):121-131
The landscape matrix is suggested to influence the effect of habitat fragmentation on species richness, but the generality
of this prediction has not been tested. Here, we used data from 10 independent studies on butterfly species richness, where
the matrix surrounding grassland patches was dominated by either forest or arable land to test if matrix land use influenced
the response of species richness to patch area and connectivity. To account for the possibility that some of the observed
species use the matrix as their main or complementary habitat, we analysed the effects on total species richness and on the
richness of grassland specialist and non-specialist (generalists and specialists on other habitat types) butterflies separately.
Specialists and non-specialists were defined separately for each dataset. Total species richness and the richness of grassland
specialist butterflies were positively related to patch area and forest cover in the matrix, and negatively to patch isolation.
The strength of the species-area relationship was modified by matrix land use and had a slope that decreased with increasing
forest cover in the matrix. Potential mechanisms for the weaker effect of grassland fragmentation in forest-dominated landscapes
are (1) that the forest matrix is more heterogeneous and contains more resources, (2) that small grassland patches in a matrix
dominated by arable land suffer more from negative edge effects or (3) that the arable matrix constitutes a stronger barrier
to dispersal between populations. Regardless of the mechanisms, our results show that there are general effects of matrix
land use across landscapes and regions, and that landscape management that increases matrix quality can be a complement to
habitat restoration and re-creation in fragmented landscapes. 相似文献
8.
We examined the use of coarse resolution land cover data (USGS LUDA) to accurately discriminate ecoregions and landscape-scale
features important to biodiversity monitoring and management. We used land cover composition and landscape indices, correlation
and principal components analysis, and comparison with finer-grained Landsat TM data, to assess how well LUDA data discriminate
changing patterns across an agriculture-forest gradient in Minnesota, U.S.A. We found LUDA data to be most accurate at general
class levels of agriculture and forest dominance (Anderson Level I), but in consistent and limited in ecotonal areas of the
gradient and within forested portions of the study region at finer classes (Anderson Level II).
We expected LUDA to over-represent major (matrix) cover types and under-represent minor types, but this was not consistent
with all classes. 1) Land cover types respond individualistically across the gradient, changing landscape grain as well as
their spatial distribution and abundance. 2) Agriculture is not over-represented where it is the dominant land cover type,
but forest is over-represented where it is dominant. 3) Individual forest types are under-represented in an open land matrix.
4) Within forested areas, mixed deciduous-coniferous forest is over-represented by several orders of magnitude and the separate
conifer and hardwood types under-represented. Across gradual, transitional agriculture-forest areas, LUDA cover class dominance
changes abruptly in a stair-step fashion. In general, rare cover types that are discrete, such as forest in agriculture or
wetlands or water in forest, are more accurately represented than cover classes having lower contrast with the matrix. Northward
across the gradient, important changes in the proportions of conifer and deciduous forest mixtures occur at scales not discriminated
by LUDA data. Results suggest that finer-grained data are needed to map within-state ecoregions and discriminate important
landscape characteristics. LUDA data, or similar coarse resolution data sources, should be used with caution and the biases
fully understood before being applied in regional landscape management.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
María José José Martín Carlos L. De Pablo Pilar Martín De Agar 《Landscape Ecology》2006,21(7):1075-1088
Changes in the landscape from 1946 to 1999 were studied according to changes in the land uses, boundaries and mosaics therein.
The abundances of the different categories of these three landscape elements were calculated using land use maps. Their frequency
profiles were compared based on their richness, evenness and diversity. Richness of land uses does not noticeably change.
However, these slight changes are spatially perceptible in the landscape when changes in the boundaries and mosaics are considered.
For the three landscape elements the least diverse landscapes are obtained in the initial year. The highest landscape diversity
is reached, however, in the intermediate years when boundaries or mosaics are considered, whereas the highest value based
on land uses occurs in the final period studied. Considering that land uses, boundaries and mosaics provide different information
on landscape characteristics and qualities, conditional entropy analyses were conducted in order to ascertain which of the
types of landscape elements is most related to landscape change. Boundaries are the element most related to landscape change.
Mosaics, however, are the element that best describe each of the years because they integrate the information on land uses
and boundaries. From an ecological and management point of view, the three elements should be considered as opposed to just
land uses. They compliment each other in the information provided by each one in relation to changes occurring and the effects
thereof on landscape structure and functioning. 相似文献
10.
Ownership and ecosystem as sources of spatial heterogeneity in a forested landscape,Wisconsin, USA 总被引：7，自引：0，他引：7
The interaction between physical environment and land ownership in creating spatial heterogeneity was studied in largely forested landscapes of northern Wisconsin, USA. A stratified random approach was used in which 2500-ha plots representing two ownerships (National Forest and private non-industrial) were located within two regional ecosystems (extremely well-drained outwash sands and moderately well-drained moraines). Sixteen plots were established, four within each combination of ownership and ecosystem, and the land cover on the plots was classified from aerial photographs using a modified form of the Anderson (U.S. Geological Survey) land use and land cover classification system.Upland deciduous forests dominated by northern hardwoods were common on the moraines for both ownerships. On the outwash, the National Forest was dominated by pine plantations, upland deciduous forests, and upland regenerating forests (as defined by <50% canopy coverage). In contrast, a more even distribution among the classes of upland forest existed on private land/outwash. A strong interaction between ecosystem and ownership was evident for most comparisons of landscape structure. On the moraine, the National Forest ownership had a finer grain pattern with more complex patch shapes compared to private land. On the outwash, in contrast, the National Forest had a coarser grain pattern with less complex patch shapes compared to private land. When patch size and shape were compared between ecosystems within an ownership, statistically significant differences in landscape structure existed on public land but not on private land. On public land, different management practices on the moraine and outwash, primarily related to timber harvesting and road building, created very different landscape patterns. Landscape structure on different ecosystems on private land tended to be similar because ownership was fragmented in both ecosystems and because ownership boundaries often corresponded to patch boundaries on private land. A complex relationship exits between ownership, and related differences in land use, and the physical environment that ultimately constrains land use. Studies that do not consider these interactions may misinterpret the importance of either variable in explaining variation in landscape patterns. 相似文献
11.
Jobin Benoît Beaulieu Jason Grenier Marcelle Bélanger Luc Maisonneuve Charles Bordage Daniel Filion Bernard 《Landscape Ecology》2003,18(6):575-590
Most landscape definitions in the western world are based on soil, climatic, or physiographic features and do not integrate
humans as an integral part of the landscape. We present an approach where landscape types have been delineated in southern
Québec, Canada based on current land use where anthropogenic and agricultural activities are concentrated as a practical application
of the holistic approach in landscape definition. Landsat-TM satellite images were classified and the 27 habitat classes were
regrouped into 5 general land cover classes (cash crop, dairy farming, forest, anthropogenic, wetlands) and overlaid onto
soil landscape polygons to characterize natural boundary units. Cluster analyses were used to aggregate these polygons into
seven agricultural types of land scape forming a gradient from urban and high-intensity cash crop farming activities to landscapes
dominated by a mosaic of agriculture and forested areas. Multivariate analyses of raw data and of socio-economic and farming
practices variables were used to describe the defined types of landscape and these were projected over three established land
classification systems of southern Québec (Canadian ecoregions, North American Bird Conservation Initiative regions and Corn
Heat Unit regions) to compare their similarity in terms of land cover and for planning of future ecological studies. Because
agricultural landscapes are highly dynamic, they are bound to undergo changes in the near future. Our landscape delineation
may serve as an experimental setup where land scape dynamics and wildlife populations and community structures could be monitored.
Because the information we used to delineate and characterize agricultural landscape types is readily available in other countries,
our approach could easily be adapted to similar data sources under and a wide variety of landscape types.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
Kiira Aaviksoo 《Landscape Ecology》1993,8(4):287-301
The dynamics of plant cover and land use types in three study areas - Keava (1192.05 ha), Meenikonna (1513.35 ha) and Nätsi-Võlla (888.61 ha) mire landscapes, each divided into natural (N) and anthropogenous (A) subareas, was investigated by repeated aerial photo (black-and-white panchromatic, 1:10,000) interpretation. Nineteen plant cover and land use (PC&LU) types were differentiated and three contour maps were drawn for each study area (corresponding to 1950's, 1960's and 1980's).The dynamics of mire landscapes were modelled by transition matrices P = [Pij], which contain the transition probabilities between i-th and j-th PC&LU types during the time interval between the aerial photographs. A total of 12 transition matrices were constructed.In A-subareas peat milling was started in the middle of the 60's whereas N-subareas acquired mire reserve status in 1981, which is manifested in a different development. 93% of N-subarea and 69% of the A-subarea remained unchanged from the 50's to the 80's. The increase of anthropogenous land use types in A-subareas of Keava, Meenikonna and Nätsi-Võlla were respectively 0.84%, 0.32% and 1.17% per year.Two different matrices (I and II period) were used to predict the future state of the study areas. The applicability of the transition matrix model has been discussed by comparing matrices of different base periods. Errors arising from photointerpretation, contour input, (transition) area measurement, matrix reduction etc. are evaluated. 相似文献
13.
Predicting land cover changes and their impact on the sediment influx in the Lake Balaton catchment 总被引：2，自引：0，他引：2
The land cover pattern in the Lake Balaton catchment (Hungary) has been changing since decollectivization in the 1990s. These
land cover changes significantly impact the landscape connectivity, controlling the influx of sediments into the lake. A comparison
of high resolution land cover maps from 1981, 2000 and 2005 showed a significant extensification of the agriculture with land
cover conversions from arable land and vineyards to grassland and forest. For each land unit transition probabilities were
assessed using logistic regression techniques to evaluate to which extent land cover changes are controlled by physical or
socio-economic parameters. A stochastic land cover allocation algorithm was applied to generate future land cover patterns.
The landscape connectivity for each of the simulated land cover patterns was assessed by means of a distributed routing algorithm.
The simulations suggest that further land abandonment in the upslope parts of the catchment will cause a non-linear reduction
of average soil erosion rates. The changes, however, have a relatively low impact on the sediment volume entering the lake
because of the land unit’s poor connectivity with permanent river channels. The major contributors to the lakes sediment load
are the vineyards near the lakeshore. They are likely to be maintained because of their touristic value. A significant reduction
of the total sediment input in the lake can be expected only if soil conservation measures in the vineyards near the shorelines
are undertaken. 相似文献
14.
Land use maps are widely used in modeling land use change, urban sprawl, and for other landscape related studies. A misclassification
confusion matrix for land use maps is usually provided as a measure of their quality and uncertainty. However, this very important
information is rarely considered in land use map based studies, especially in modeling landscape dynamics. Ignoring uncertainty
of land use maps may cause models to provide unreliable predictions. This study is an attempt to investigate the impact of
the accuracy of land use maps used as input for an urban sprawl model. In the study area, the regional confusion matrix has
been localized using a topographical map. Based on the regional and local confusion matrices, several error levels have been
defined. The results showed that a localized confusion matrix that reflected the characteristics of the study area had error
rates that were much different than the regional confusion matrix. The predictions of the probability of urban sprawl based
on the land use maps and defined error levels were quite different. 相似文献
15.
We describe the Pathway Analysis Through Habitat (PATH) tool, which can predict the location of potential corridors of animal
movement between patches of habitat within any map. The algorithm works by launching virtual entities that we call `walkers'
from each patch of habitat in the map, simulating their travel as they journey through land cover types in the intervening
matrix, and finally arrive at a different habitat `island.' Each walker is imbued with a set of user-specified habitat preferences
that make its walking behavior resemble a particular animal species. Because the tool operates in parallel on a supercomputer,
large numbers of walkers can be efficiently simulated. The importance of each habitat patch as a source or a sink for a species
is calculated, consistent with existing concepts in the metapopulation literature. The manipulation of a series of contrived
artificial landscapes demonstrates that the location of potential dispersal corridors and relative source and sink importance
among patches can be purposefully altered in expected ways. Finally, potential dispersal corridors are predicted among remnant
woodlots within three actual landscape maps.
The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
16.
Mapping and analyzing landscape patterns 总被引：5，自引：0，他引：5
Landscapes were mapped as clusters of 2 or 3 land cover** types, based on their pattern within the clusters and tendency for a single type to dominate. These landscapes, called Landscape Pattern Types (LPTs), were combined with other earth surface feature data in a Geographic Information System (GIS) to test their utility as analysis units. Road segment density increased significantly as residential and urbanized land cover components increased from absent, to present as patch, to present as matrix (i.e., the dominant land cover type). Stream segment density was significantly lower in LPTs with an urbanized or residential matrix than in LPTs with either a forest or agriculture matrix, suggesting an inverse relationship between stream network density and the prevalence of human development other than agriculture in the landscape. The ratio of average forest patch size to total forest in the LPT unit decreased as agriculture replaced forest, then increased as residential and urban components dominated. Wetland fractal dimension increased as agriculture and residential land cover components of LPTs increased. Comparison of LPT and LUDA land cover area statistics in ecoregions suggested that land cover data alone does not provide information as to its spatial arrangement. 相似文献
17.
Robert H. Gardner Todd R. Lookingbill Philip A. Townsend Joseph Ferrari 《Landscape Ecology》2008,23(5):513-526
The resolution of satellite imagery must often be increased or decreased to fill data gaps or match preexisting project requirements.
It is well known that a change in resolution introduces systematic errors of size, shape, location and amount of contiguous
land cover types. Nevertheless, robust methods for rescaling landscape data are frequently required to assess patterns of
landscape change through time and over large areas. We developed a new method for rescaling spatial data that allows map resolution
(grain size) to be either increased or decreased while holding the total proportion of land cover types constant. The method
uses a weighted sampling net of variable resolution to sample an existing map and then randomly selects from the frequency
of cover types derived from this sample to assign the cover type for the corresponding location in the rescaled map. The properties
of the sampling net had a variable effect on measures of landscape pattern with the characteristic patch size (S) the most robust metric and the number of clusters (A) the most variable. A comparison of up-scaled and down-scaled maps showed that this process is not symmetrical, producing
different errors for increases versus decreases in grain size. Rescaling Landsat (30 m) imagery to the 10 m resolution of
SPOT imagery for four National Park units within Maryland and Virginia resulted in errors due to rescaling that were small
(1–2%) relative to the total error (∼11%) associated with these images. The new rescaling method is general because it provides
a single method for increasing or decreasing resolution, can be applied to maps with multiple land cover types, allows grid
geometry to be transformed (i.e., square to hexagonal grids), and provide a more consistent basis for landscape comparisons
when maps must be derived from multiple sources of classified imagery. 相似文献
18.
Forest roads and landscape structure in the southern Rocky Mountains 总被引：18，自引：0，他引：18
Roadless areas on public lands may serve as environmental baselines against which human-caused impacts on landscape structure can be measured. We examined landscape structure across a gradient of road densities, from no roads to heavily roaded, and across several spatial scales. Our study area was comprised of 46,000 ha on the Roosevelt National Forest in north-central Colorado. When forest stands were delineated on the basis of seral stage and covertype, no relationship was evident between average stand size and road density. Topography appeared to exert a greater influence on average stand size than did road density. There was a significant positive correlation between the fractal dimension of forest stands and road density across all scales. Early-seral stands existed in greater proportions adjacent to roads, suggesting that the effects of roads on landscape structure are somewhat localized. We also looked at changes in landscape structure when stand boundaries were delineated by roads in addition to covertype and seral stage. Overall, there was a large increase in small stands with simple shapes, concurrent with a decline in the number of stands > 100 ha. We conclude that attempts to quantify the departure from naturalness in roaded areas requires an understanding of the factors controlling the structure of unroaded landscapes, particularly where the influence of topography is great. Because roads in forested landscapes influence a variety of biotic and abiotic processes, we suggest that roads should be considered as an inherent component of landscape structure. Furthermore, plans involving both the routing of new roads and the closure of existing ones should be designed so as to optimize the structure of landscape mosaics, given a set of conservation goals. 相似文献
19.
The declines of many specialist bird species in the agricultural landscapes of Central Europe have resulted in small and isolated
populations. In the case of the black grouse, a ground-nesting bird species with large spatial requirements, empiric evidence
about underlying landscape changes is scarce. In this study, we examined land cover and land cover changes in a farmland-forest
mosaic in eastern Lower Saxony, Germany and how they affect occurrence and persistence of black grouse. Spatial information
came from historic topographic maps from 1958 to 1975. The results show profound conversions of habitat to forest and farmland
but also an increase in settlement area. Habitat conversions and suburbanization were negative correlates of black grouse
persistence. Habitat models from before and after a decline period differed in some of the predictors and suggest black grouse
habitat to be more diverse before the land cover changes. Our study confirms that land use factors at a landscape scale extent
contribute to explain black grouse occurrence and thus can complement important small scale factors like the quality and size
of individual habitat patches. Results also show that landscape factors affect black grouse distribution predominantly from
an area much greater than an individual black grouse home range. Our models may be further evaluated on present-day landscapes
and might be used to evaluate large-scale habitat availability for black grouse. 相似文献
20.
Spatial simulation of landscape changes in Georgia: A comparison of 3 transition models 总被引：20，自引：1，他引：19
Monica Goigel Turner 《Landscape Ecology》1987,1(1):29-36
Spatial simulation models were developed to predict temporal changes in land use patterns in a piedmont county in Georgia (USA). Five land use categories were included: urban, cropland, abandoned cropland, pasture, and forest. Land use data were obtained from historical aerial photography and digitized into a matrix based on a 1 ha grid cell format. Three different types of spatial simulation were compared: (1) random simulations based solely on transition probabilities; (2) spatial simulations in which the four nearest neighbors (adjacent cells only) influence transitions; and (3) spatial simulations in which the eight nearest neighbors (adjacent and diagonal cells) influence transitions. Models and data were compared using the mean number and size of patches, fractal dimension of patches, and amount of edge between land uses. The random model simulated a highly fragmented landscape having numerous, small patches with relatively complex shapes. The two versions of the spatial model simulated cropland well, but simulated patches of forest and abandoned cropland were fewer, larger, and more simple than those in the real landscape. Several possible modifications of model structure are proposed. The modeling approach presented here is a potentially general one for simulating human-influenced landscapes. 相似文献