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1.
Use of fourier transforms to define landscape scales of analysis for disturbances: a case study of thinned and unthinned forest stands 总被引：1，自引：0，他引：1
Various disturbances such as disease and management practices causecanopy gaps that change patterns of forest stand structure. This study examinedthe usefulness of digital image analysis using aerial photos, FourierTranforms,and cluster analysis to investigate how different spatial statistics areaffected by spatial scale. The specific aims were to: 1) evaluate how a Fourierfilter could be used to classify canopy gap sizes objectively, 2) determinewhich statistics might be useful for detecting and measuring disturbanceimpacts, and 3) examine the potential for this method to determine spatialdomains in a pair of ponderosa pine (Pinusponderosa) stands in the Black Hills of South Dakota,USA.The eventual goal is to develop an operational method of assessing the impactsof natural disturbances such as disease. Results indicated that several spatialmetrics discriminated between harvested and unharvested stands. We hypothesizethat these metrics will be useful as spatial measures of disease impact if theanalyses are performed on specific size classes of forest gaps.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
2.
Effects of remote sensor spatial resolution and data aggregation on selected fragmentation indices 总被引：3，自引：0，他引：3
Santiago Saura 《Landscape Ecology》2004,19(2):197-209
Analyzing the effect of scale on landscape pattern indices has been a key research topic in landscape ecology. The lack of
comparability of fragmentation indices across spatial resolutions seriously limits their usefulness while multi-scale remotely
sensed data are becoming increasingly available. In this paper, we examine the effect of spatial resolution on six common
fragmentation indices that are being used within the Third Spanish National Forest Inventory. We analyse categorical data
derived from simultaneously gathered Landsat-TM and IRS-WiFS satellite images, as well as TM patterns aggregated to coarser
resolutions through majority rules. In general, majority rules tend to produce more fragmented patterns than actual sensor
ones. It is suggested that sensor point spread function should be specifically considered to improve comparability among satellite
images of varying pixel sizes. Power scaling-laws were found between spatial resolution and several fragmentation indices,
with mean prediction errors under 10% for number of patches and mean patch size and under 5% for edge length. All metrics
but patch cohesion indicate lower fragmentation at coarser spatial resolutions. In fact, an arbitrarily large value of patch
cohesion can be obtained by resampling the pattern to smaller pixel sizes. An explanation and simple solution for correcting
this undesired behaviour is provided. Landscape division and largest patch index were found to be the least sensitive indices
to spatial resolution effects.
This revised version was published online in May 2005 with corrections to the Cover Date.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Landscape metrics with ecotones: pattern under uncertainty 总被引：1，自引：0，他引：1
4.
Anthropogenic influences on potential fire spread in a pyrogenic ecosystem of Florida, USA 总被引：1，自引：1，他引：1
Fire has historically been an important ecological factor maintaining southeastern U.S. vegetation. Humans have altered natural
fire regimes by fragmenting fuels, introducing exotic species, and suppressing fires. Little is known about how these alterations
specifically affect spatial fire extent and pattern. We applied historic (1920 and 1943) and current (1990) GIS fuels maps
and the FARSITE fire spread model to quantify the differences between historic and current fire spread distributions. We held
all fire modeling variables (wind speed and direction, cloud cover, precipitation, humidity, air temperature, fuel moistures,
ignition source and location) constant with exception of the fuel models representing different time periods. Model simulations
suggest that fires during the early 1900's burned freely across the landscape, while current fires are much smaller, restricted
by anthropogenic influences. Fire extent declined linearly with patch density, and there was a quadratic relationship between
fire extent and percent landscape covered by anthropogenic features. We found that as little as 10 percent anthropogenic landcover
caused a 50 percent decline in fire extent. Most landscapes (conservation or non-conservation areas) are now influenced by
anthropogenic features which disrupt spatial fire behavior disproportionately to their actual size. These results suggest
that land managers using fire to restore or maintain natural ecosystem function in pyrogenic systems will have to compensate
for anthropogenic influences in their burn planning.
This revised version was published online in May 2005 with corrections to the Cover Date.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
Although the landscape matrix is increasingly incorporated into spatial-ecological population studies, little consideration
has been given to the likely possibility that patch quality is confounded with the composition of the matrix surrounding each
patch. For example, the nutritional quality of host-plant patches to an herbivore may be highly correlated with matrix composition,
consequently obfuscating the importance of the matrix itself to interpatch dispersal. From a literature survey of the effects
of the matrix on herbivore movement among host-plant patches, we found that 55% of the studies (6/11) failed to experimentally
or statistically isolate the effects of the matrix from potential patch-quality effects on dispersal. Most studies consisted
of mark-recapture experiments in natural landscapes where patch equality was not controlled or manipulated. Of the few studies
that evaluated the relationship between matrix composition and patch quality, all of them (3/3) found that these two landscape
factors covaried. These data suggest that in most matrix studies, effects of the matrix on dispersal may be wholly, or in
part, due to underlying differences in patch quality.
This revised version was published online in May 2005 with corrections to the Cover Date.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
The Hierarchical Patch Dynamics Paradigm provides a conceptual framework for linking pattern, process and scale in ecosystems,
but there have been few attempts to test this theory because most ecological studies focus on only one spatial scale, or are
limited in their temporal scope. Here I use palaeoecological techniques (analysis of fossil pollen and stable carbon isotopes)
to compare vegetation heterogeneity in an east African savanna at three spatial scales, over hundreds of years. The data show
that patterns of vegetation change are different at the three spatial scales of observation, and suggest that different ecological
processes dominate tree abundance at micro, local and landscape scales. Interactions between plants, disturbance (e.g., by
fire and herbivores), climate and soil type may influence tree density at differing spatial and temporal scales. This hierarchical
explanation of savanna vegetation dynamics could inform future biodiversity conservation and management in savannas.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Lindsey Gillson 《Landscape Ecology》2005,19(8):883-894
The Hierarchical Patch Dynamics Paradigm provides a conceptual framework for linking pattern, process and scale in ecosystems,
but there have been few attempts to test this theory because most ecological studies focus on only one spatial scale, or are
limited in their temporal scope. Here I use palaeoecological techniques (analysis of fossil pollen and stable carbon isotopes)
to compare vegetation heterogeneity in an east African savanna at three spatial scales, over hundreds of years. The data show
that patterns of vegetation change are different at the three spatial scales of observation, and suggest that different ecological
processes dominate tree abundance at micro, local and landscape scales. Interactions between plants, disturbance (e.g., by
fire and herbivores), climate and soil type may influence tree density at differing spatial and temporal scales. This hierarchical
explanation of savanna vegetation dynamics could inform future biodiversity conservation and management in savannas.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Westphal Michael I. Field S.A. Tyre A.J. Paton D. Possingham H.P. 《Landscape Ecology》2003,18(4):413-426
We assessed how well landscape metrics at 2, 5, and 10 km scales could explain the distribution of woodland bird species in
the Mount Lofty Ranges, South Australia. We considered 31 species that have isolated or partially isolated populations in
the region and used the Akaike Information Criterion to select a set of candidate logistic regression models. The 2 km distance
was the most appropriate scale for a plurality of the species. While the total amount of area of native vegetation around
a site was the most important determining factor, the effect of landscape configuration was also important for many species.
Most species responded positively to area-independent fragmentation, but the responses to mean patch isolation and mean patch
shape were more variable. Considering a set of candidate models for which there is reasonable support (Akaike weights > 0.10),
12 species responded negatively to landscapes with highly linear and isolated patches. No clear patterns emerged in terms
of taxonomy or functional group as to how species respond to landscape configuration. Most of the species had models with
relatively good discrimination (12 species had ROC values > 0.70), indicating that landscape pattern alone can explain their
distributions reasonably well. For six species there were no models that had strong weight of evidence, based on the AIC and
ROC criteria. This analysis shows the utility of the Akaike Information Criterion approach to model selection in landscape
ecology. Our results indicate that landscape planners in the Mount Lofty Ranges must consider the spatial configuration of
vegetation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Existing spatial patterns of a forest are in part a product of its disturbance history. Using laser altimetry and field measures
of canopy top height to represent pre- and post-hurricane canopy topography, respectively, we measured changes in spatial
patterns of stand structure of a United States southern mixed coniferous-deciduous for est. Autocorrelative and fractal properties
were measured in this opportunistic study to quantify changes in canopy architecture along twelve, 190-250 m transects that
were subjected to moderate to high levels of wind disturbance. Prior to the hurricane, canopy heights were autocorrelated
at scales <40 m with an average fractal dimension of 1.71. After the disturbance, autocorrelation disappeared; the average
fractal dimension rose to 1.94. This shift towards spatial randomness illustrates part of the cyclical nature of ecosystem
development. It shows how a catastrophic collapse of biomass accumulation corresponds to a decrease in ecosystem organization
across a landscape.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
The urban landscape is by nature the result of many cultural and natural factors and processes. Cityscape associated with
land attributes and human activities expresses a city's social and economic functions. Treescape in the form of species composition,
tree dimension and tree performance echoes ecological and environmental functions. The cityscape can be denoted by urban factors,
such as tree growing-space condition, tree management regime, human activities and planting history. The hypothesis that the
cityscape plays a key role in molding the treescape is tested. Nanjing, an east China city notable for its high tree coverage,
is chosen as the study area. A quantitative method has been developed to assess the relationship between cityscape and treescape.
Based on statistical analyses on the surveyed results of 6527 trees and related cityscape attributes, this paper explores
the pertinent patterns and underlying factors of treescape variations. Species composition has the strongest association with
cityscape. Roadside and factories have lower species diversity. Residential and industrial land uses show smaller tree dimension.
Trees in residential, commercial, heavy industrial land-uses perform below par. A three-way classification has been developed
to examine the effects of urban factors on treescape at different cityscape scales. At the small scale, a well-vegetated groundcover
will ensure better tree performance and a lower management burden. The medium-scale cityscape (land-use and habitat) is preferred
in the study of treescape attributes and their spatial variations, and is suitable for urban tree planning and management.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Spatial analysis of roadside Acacia populations on a road network using the network K-function 总被引：3，自引：0，他引：3
Spatial patterning of plant distributions has long been recognised as being important in understanding underlying ecological processes. Ripley’s K-function is a frequently used method for studying the spatial pattern of mapped point data in ecology. However, application of this method to point patterns on road networks is inappropriate, as the K-function assumes an infinite homogenous environment in calculating Euclidean distances. A new technique for analysing the distribution of points on a network has been developed, called the network K-function (for univariate analysis) and network cross K-function (for bivariate analysis). To investigate its applicability for ecological data-sets, this method was applied to point location data for roadside populations of three Acacia species in a fragmented agricultural landscape of south-eastern Australia. Kernel estimations of the observed density of spatial point patterns for each species showed strong spatial heterogeneity. Combined univariate and bivariate network K-function analyses confirmed significant clustering of populations at various scales, and spatial patterns of Acacia decora suggests that roadworks activities may have a stronger controlling influence than environmental determinants on population dynamics. The network K-function method will become a useful statistical tool for the analyses of ecological data along roads, field margins, streams and other networks.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
12.
Fulé Peter Z. Crouse Joseph E. Heinlein Thomas A. Moore Margaret M. Covington W. Wallace Verkamp Greg 《Landscape Ecology》2003,18(5):465-486
Fire regime characteristics of high-elevation forests on the North Rim of the Grand Canyon, Arizona, were reconstructed from fire scar analysis, remote sensing, tree age, and forest structure measurements, a first attempt at detailed reconstruction of the transition from surface to stand-replacing fire patterns in the Southwest. Tree densities and fire-/non-fire-initiated groups were highly mixed over the landscape, so distinct fire-created stands could not be delineated from satellite imagery or the oldest available aerial photos. Surface fires were common from 1700 to 1879 in the 4,400 ha site, especially on S and W aspects. Fire dates frequently coincided with fire dates measured at study sites at lower elevation, suggesting that pre-1880 fire sizes may have been very large. Large fires, those scarring 25% or more of the sample trees, were relatively infrequent, averaging 31 years between burns. Four of the five major regional fire years occurred in the 1700s, followed by a 94-year gap until 1879. Fires typically occurred in significantly dry years (Palmer Drought Stress Index), with severe drought in major regional fire years. Currently the forest is predominantly spruce-fir, mixed conifer, and aspen. In contrast, dendroecological reconstruction of past forest structure showed that the forest in 1880 was very open, corresponding closely with historical (1910) accounts of severe fires leaving partially denuded landscapes. Age structure and species composition were used to classify sampling points into fire-initiated and non-fire-initiated groups. Tree groups on nearly 60% of the plots were fire-initiated; the oldest such groups appeared to have originated after severe fires in 1782 or 1785. In 1880, all fire-initiated groups were less than 100 years old and nearly 25% of the groups were less than 20 years old. Non-fire-initiated groups were significantly older (oldest 262 years in 1880), dominated by ponderosa pine, Douglas-fir, or white fir, and occurred preferentially on S and W slopes. The mixed-severity fire regime, transitioning from lower-elevation surface fires to mixed surface and stand-replacing fire at higher elevations, appeared not to have been stable over the temporal and spatial scales of this study. Information about historical fire regime and forest structure is valuable for managers but the information is probably less specific and stable for high-elevation forests than for low-elevation ponderosa pine forests.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
13.
The goals of landscape planning are multiple for rural ecosystems of the resettlement area in the Hubei Province of China. They relate to the types, diversity and patterns of the ecosystems, and to the conservation of ecosystem functions and biodiversity. We were interested in the improvement of socio-economic conditions, and the promotion of the development of farmland ecosystems and natural forest ecosystems. The landscape planning took into account the conservation and the restoration of forestlands, and the reconstructions of farmlands, towns and villages. The areas of towns and villages were assigned by trade-off analysis balancing ecological, economic and social benefits. The spatial pattern of used lands was designed by a multi-criteria optimal spatial planning, resulting in the strengthening of some primary ecosystem functions. In the resettlement area forests will expand to a matrix, and cropland patches together with tree fences will form patch-corridor systems. Significant ecological, economic and social benefits can be derived from this landscape pattern.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
14.
Traditional agricultural mosaic landscapes are likely to undergo dramatic changes through either intensification or abandonment
of land use. Both developmental trends may negatively affect the vascular plant species richness of such landscapes. Therefore,
sustainable land-use systems need to be developed to maintain and re-establish species richness at various spatial scales.
To evaluate the sustainability of specific land-use systems, we need approaches for the effective assessment of the present
species richness and models that can predict the effects on species richness as realistically as possible. In this context,
we present a methodology to estimate and predict vascular plant species richness at the local and the regional scale. In our
approach, the major determinants of vascular plant species richness within the study area are taken into consideration: These
are according to Duelli's mosaic concept the number of habitat types and of habitat patches within area units. Furthermore,
it is based on the relative frequencies of species within habitat types. Our approach comprises six steps: (i) the determination
of present habitat patterns within an observation area, (ii) the creation of a land-use scenario with simulated habitat patterns,
(iii) the determination of species frequencies within habitat types of this area, (iv) a grouping of habitat-specific species,
(v) the estimation of the probabilities for all species (or habitat specialists) to occur, either in stepwise, exponentially
enlarged landscape tracts (local scale), or in the entire observation area (regional scale), and (vi) the validation of the
estimated species numbers. The approach will be exemplified using data from the municipal district of Erda, Lahn-Dill Highlands,
Germany. The current species numbers to be expected on the basis of probability calculations were compared with those recorded
on the basis of extensive field work. This comparison shows that, on the basis of our simple calculations, the current local
plant species richness can be predicted well, with a slight underestimation.
This revised version was published online in May 2005 with corrections to the Cover Date.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
Effects of patch attributes, barriers, and distance between patches on the distribution of a rock-dwelling rodent (Lagidium viscacia) 总被引：1，自引：0，他引：1
We tested whether size of habitat patches and distance between patches are sufficient to predict the distribution of the mountain
vizcacha Lagidium viscacia a large, rock-dwelling rodent of the Patagonian steppe Argentina, or whether information on other patch and landscape characteristics
also is required. A logistic regression model including the distance between rock crevices and depth of crevices, distance
between a patch and the nearest occupied patch, and whether or not there was a river separating it from the nearest occupied
patch was a better predictor of patch occupancy by mountain vizcachas than was a model based only on patch size and distance
between patches. Our results indicate that a simple metapopulation analysis based on size of habitat patches and distance
between patches may not provide an accurate representation of regional population dynamics if patches vary in habitat quality
independently of patch size and features in the matrix alter connectivity.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Ludwig John A. Eager Robert W. Bastin Gary N. Chewings Vanessa H. Liedloff Adam C. 《Landscape Ecology》2002,17(2):157-171
The cover, number, size, shape, spatial arrangement and orientation of vegetation patches are attributes that have been used
to indicate how well landscapes function to retain, not ‘leak’, vital system resources such as rainwater and soil. We derived
and tested a directional leakiness index (DLI) for this resource retention function. We used simulated landscape maps where
resource flows over map surfaces were directional and where landscape patch attributes were known. Although DLI was most strongly
related to patch cover, it also logically related to patch number, size, shape, arrangement and orientation. If the direction
of resource flow is multi-directional, a variant of DLI, the multi-directional leakiness index (MDLI) can be used. The utility
of DLI and MDLI was demonstrated by applying these indices to three Australian savanna landscapes differing in their remotely
sensed vegetation patch attributes. These leakiness indices clearly positioned these three landscapes along a function-dysfunction
continuum, where dysfunctional landscapes are leaky (poorly retain resources).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Disturbance and landscape dynamics in the Chequamegon National Forest Wisconsin,USA, from 1972 to 2001 总被引：6，自引：2，他引：6
Bresee Mary K. Le Moine Jim Mather Stephen Brosofske Kimberley D. Chen Jiquan Crow Thomas R. Rademacher John 《Landscape Ecology》2004,19(3):291-309
Land uses, especially harvesting and road building, are considered to be the primary cause of forest fragmentation in many parts of the world. To test this perception, we (1) quantified changes and rates of change in vegetative composition and structure within the Washburn Ranger District in northern Wisconsin using Landsat images, (2) examined changes in landscape structure, (3) assessed changes within the area of road influence (ARI), and (4) investigated changes in landscape composition and structure within the context of forest management activities. Our landscape classifications included six dominant cover types: mixed hardwood (MH), jack pine (JP), red pine (RP), mixed hardwood/conifer (MHC), non-forested bare ground (NFBG), and regenerating forest or shrub (RFS). Increases in NFBG and RFS, by 196% and 28% respectively, reflect expansion of the pine-barrens. Windthrow in the mature hardwoods during the late 1970s and jack pine budworm outbreaks during the mid-1990s correlated with decreases in those classes over the corresponding intervals. A 69% decrease in mean patch size and a 60% increase in edge density reflect increased fragmentation. An inverse relationship existed between the compositional trends of forested (excluding JP) cover types and RFS and NFBG cover types. ARI covered 8% of the landscape affecting species composition within the MH, RFS, and NFBG. Results from this study are key in assessing the links between management activities and ecological consequences and thereby facilitate adaptive management.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
18.
Landscape patch shape complexity as an effective measure for plant species richness in rural landscapes 总被引：13，自引：0，他引：13
Moser Dietmar Zechmeister Harald G. Plutzar Christoph Sauberer Norbert Wrbka Thomas Grabherr Georg 《Landscape Ecology》2002,17(7):657-669
The application of landscape patch shape complexity as a predictor ofvascularplant and bryophyte species richness is analysed. Several common complexityindices (shape index, fractal dimension, comparison to the area of the minimumbounding rectangle) are tested for their predictive power for plant speciesrichness. One new robust measure for shape complexity is presented whichovercomes some disadvantages of common complexity measures applied to highresolution analysis of agricultural landscapes based on aerial photographs. Thenew index is based on the number of shape characterising points along apolygons boundary. This new measure shows promising predictive capabilitiesforspecies richness of vascular plants and bryophytes (correlation coefficient:0.85 for vascular plants, 0.74 for bryophytes).This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
19.
Incorporating landscape elements into a connectivity measure: a case study for the Speckled wood butterfly (Pararge aegeria L.) 总被引：5，自引：6，他引：5
In spatial studies of populations, Euclidean distance is commonly used to measure the structural connectivity between habitat
patches. The role of the matrix on patch connectivity is thereby ignored. However, the importance of the matrix for (dispersal)
movement is increasingly being acknowledged. Our study compared the cost-distance measure with the Euclidean distance. The
cost-distance is a simple GIS-calculated connectivity measure that incorporates the resistance of the landscape matrix to
movement behaviour. We used presence-absence data from a field study on the Speckled wood butterfly in two Belgian landscapes.
Logistic regression revealed that the cost-distance measure had a significantly better predictive power than the Euclidean
distance. This result was consistent for all the six sets of different matrix resistance values. In our study the cost-distance
proves to be a better connectivity measure than the Euclidean distance.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
Effects of area and isolation of woodland patches on herbaceous plant species richness across Great Britain 总被引：5，自引：2，他引：5
Petit Sandrine Griffiths Leila Smart Simon S. Smith Geoff M. Stuart Rick C. Wright Simon M. 《Landscape Ecology》2004,19(5):463-471
Richness of Ancient Woodland Indicator plant species was analysed in 308 woodland patches that were surveyed during the Countryside Survey of Great Britain carried out in 1998. The Countryside Survey recorded vegetation plots and landscape structure in 569 stratified 1 km sample squares and developed a remotely-sensed land cover map of the UK. Using these datasets, we tested the hypothesis that Ancient Woodland Indicator species richness in woodland fragments was limited by patch area, shape and spatial isolation and that woodland patches located in the lowland region of Great Britain would respond differently than those in the upland region. The variation in Ancient Woodland Indicator species richness in the British lowlands (n = 218) was mainly explained by patch area and two measures of connectivity, the length of hedgerows and lines of trees in the 1 km square and the area of woodland within 500 m of the vegetation plot. By contrast, variation in Ancient Woodland Indicator species richness in the British uplands (n = 90) was related to Ellenberg scores of the vegetation communities sampled – a surrogate for habitat quality – and no significant effect of spatial structure was detected. It therefore appears that the degree of fragmentation of woodland in the British lowlands limits the distribution of Ancient Woodland Indicator species, while in the uplands, failed colonisation is a matter of habitat quality rather than a result of landscape structure.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献