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1.
The purpose of our study was to compare the number, proportion, and species composition of introduced plant species in forest
patches situated within predominantly forested, agricultural, and urban landscapes. A previous study suggested that agricultural
landscape context does not have a large effect on the proportion of introduced species in forest patches. Therefore, our main
goal was to test the hypothesis that forest patches in an urban landscape context contain larger numbers and proportions of
non-native plant species. We surveyed the vegetation in 44 small remnant forest fragments (3–7.5 ha) in the Ottawa region;
15 were situated within forested landscapes, 18 within agricultural landscapes, and 11 within urban landscapes. Forest fragments
in urban landscapes had about 40% more introduced plant species and a 50% greater proportion of introduced plant species than
fragments found in the other two types of landscape. There was no significant difference in the number or proportion of introduced
species in forest fragments within forested vs. agricultural landscapes. However, the species composition of introduced species
differed among the forest patches in the three landscape types. Our results support the hypothesis that urban and suburban
areas are important foci for spread of introduced plant species. 相似文献
2.
Michelle M. Steen-Adams David J. Mladenoff Nancy E. Langston Feng Liu Jun Zhu 《Landscape Ecology》2011,26(8):1165-1178
Landscape ecology studies have demonstrated that past modifications of the landscape frequently influence its structure, highlighting
the utility of integrating historical perspectives from the fields of historical ecology and environmental history. Yet questions
remain for historically-informed landscape ecology, especially the relative influence of social factors, compared to biophysical
factors, on long-term land-cover change. Moreover, methods are needed to more effectively link history to ecology, specifically
to illuminate the underlying political, economic, and cultural forces that influence heterogeneous human drivers of land-cover
change. In northern Wisconsin, USA, we assess the magnitude of human historical forces, relative to biophysical factors, on
land-cover change of a landscape dominated by eastern white pine (Pinus strobus L.) forest before Euro-American settlement. First, we characterize land-cover transitions of pine-dominant sites over three
intervals (1860–1931; 1931–1951; 1951–1987). Transition analysis shows that white pine was replaced by secondary successional
forest communities and agricultural land-covers. Second, we assess the relative influence of a socio-historical variable (“on-/off-Indian
reservation”), soil texture (clay and sand), and elevation on land-cover transition. On the Lake Superior clay plain, models
that combine socio-historical and biophysical variables best explain long-term land-cover change. The socio-historical variable
dominates: the magnitude and rate of land-cover change differs among regions exposed to contrasting human histories. Third,
we developed an integrative environmental history-landscape ecology approach, thereby facilitating linkage of observed land-cover
transitions to broader political, economic, and cultural forces. These results are relevant to other landscape investigations
that integrate history and ecology. 相似文献
3.
Analysing land-cover changes in relation to environmental variables in Hesse,Germany 总被引:14,自引:7,他引:14
Land-use and land-cover changes affect ecological landscape functions and processes. Hence, landscape ecologists have a central interest in a comprehensive understanding of such changes. Our study focuses on the relationships between environmental conditions and agricultural land-cover changes. We present a method to (i) characterise the major spatial-temporal processes of land-cover changes, (ii) identify the correlations between environmental attributes and land-cover changes and (iii) derive potential environmental drivers of land-cover changes in a German marginal rural landscape. The method was applied to study land-cover dynamics from 1945 to 1998 in the districts of Erda, Steinbrücken and Eibelshausen, situated in the marginal rural landscape of the Lahn-Dill Highlands, Germany. We employed land-cover data gained by the interpretation of multi-temporal aerial photographs. Various environmental variables were introduced into the analyses. We identified physical landscape attributes (elevation, slope, aspect, available water capacity and soil texture) and structural landscape dimensions (patch size, patch shape and distance between patch and nearest settlement). With the aid of GIS, K-means partitioning and canonical correspondence analysis, we investigated land-cover trajectory types, land-cover transitions at individual time intervals and their relationships to these environmental variables. Our results show that, between 1945 and 1998, land-cover changes correlated with the physical attributes of the underlying landscape. On the other hand, the structural landscape dimensions correlated with land cover only in periods of minor land-cover changes (1972–98). Greater diversity of physical landscape attributes is correlated with greater land-cover dynamics. Besides the important influence of socio-economic factors, land-cover changes in the study areas took place within the relatively stable physical constraints of the underlying landscape.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
4.
The objective of this paper is to identify land-cover types where fire incidence is higher (preferred) or lower (avoided)
than expected from a random null model. Fire selectivity may be characterized by the number of fires expected in a given land-cover
class and by the mean surface area each fire will burn. These two components of fire pattern are usually independent of each
other. For instance, fire number is usually connected with socioeconomic causes whereas fire size is largely controlled by
fuel continuity. Therefore, on the basis of available fire history data for Sardinia (Italy) for the period 2000–2004 we analyzed
fire selectivity of given land-cover classes keeping both variables separate from each other. The results obtained from analysis
of 13,377 fires show that for most land-cover classes fire behaves selectively, with marked preference (or avoidance) in terms
of both fire number and fire size. Fire number is higher than expected by chance alone in urban and agricultural areas. In
contrast, in forests, grasslands, and shrublands, fire number is lower than expected. In grasslands and shrublands mean fire
size is significantly larger than expected from a random null model whereas in urban areas, permanent crops, and heterogeneous
agricultural areas there is significant resistance to fire spread. Finally, as concerns mean fire size, in our study area
forests and arable land burn in proportion to their availability without any significant tendency toward fire preference or
avoidance. The results obtained in this study contribute to fire risk assessment on the landscape scale, indicating that risk
of wildfire is closely related to land cover. 相似文献
5.
Karen Riva-Murray Rachel Riemann Peter Murdoch Jeffrey M. Fischer Robin Brightbill 《Landscape Ecology》2010,25(10):1489-1503
Widespread and increasing urbanization has resulted in the need to assess, monitor, and understand its effects on stream water
quality. Identifying relations between stream ecological condition and urban intensity indicators such as impervious surface
provides important, but insufficient information to effectively address planning and management needs in such areas. In this
study we investigate those specific landscape metrics which are functionally linked to indicators of stream ecological condition,
and in particular, identify those characteristics that exacerbate or mitigate changes in ecological condition over and above
impervious surface. The approach used addresses challenges associated with redundancy of landscape metrics, and links landscape
pattern and composition to an indicator of stream ecological condition across a broad area of the eastern United States. Macroinvertebrate
samples were collected during 2000–2001 from forty-two sites in the Delaware River Basin, and landscape data of high spatial
and thematic resolution were obtained from photointerpretation of 1999 imagery. An ordination-derived ‘biotic score’ was positively
correlated with assemblage tolerance, and with urban-related chemical characteristics such as chloride concentration and an
index of potential pesticide toxicity. Impervious surface explained 56% of the variation in biotic score, but the variation
explained increased to as high as 83% with the incorporation of a second land use, cover, or configuration metric at catchment
or riparian scales. These include land use class-specific cover metrics such as percent of urban land with tree cover, forest
fragmentation metrics such as aggregation index, riparian metrics such as percent tree cover, and metrics related to urban
aggregation. Study results indicate that these metrics will be important to monitor in urbanizing areas in addition to impervious
surface. 相似文献
6.
Land cover change, predominantly habitat conversion to agricultural use and urbanization, has recently been recognized as
the primary cause of biodiversity loss in terrestrial ecosystems. We evaluated the relative effects of urban and agricultural
landscapes on anuran species richness and the abundance of six anuran species found at breeding ponds in and around the cities
of Ottawa, Ontario and Gatineau, Quebec. We performed six call surveys at 29 permanent focal ponds surrounded by one of three
landscape contexts: primarily urban, primarily agricultural, and primarily forested. We also measured three local pond variables
to control for the effects of local habitat quality in our analyses. We found that anuran species richness was significantly
lower in breeding ponds in urban landscapes compared to forested and agricultural landscapes, which exhibited no significant
difference in species richness. The abundances of individual anuran species were also consistently lower in urban landscapes
for all species except one, which exhibited no response to landscape type. Three species had their highest abundances in ponds
in forested landscapes, whereas two species had their highest abundances in ponds in agricultural landscapes. We conclude
that ponds embedded in urban landscapes support lower biodiversity than ponds in agricultural settings. We suggest that landscapes
composed of a mosaic of forest and open habitats surrounding wetlands would hold the highest biodiversity of these species. 相似文献
7.
Pablo González-Moreno Joan Pino David Carreras Corina Basnou Iván Fernández-Rebollar Montserrat Vilà 《Landscape Ecology》2013,28(5):891-903
Landscape pattern might be an important determinant of non-native plant invasions because it encompasses components influencing the availability of non-native plant propagules and disturbance regimes. We aimed at exploring the relative role of patch and landscape characteristics, compared to those of habitat type and regional human influence on non-native plant species richness. For this purpose, we identified all non-native plant species in 295 patches of four coastal habitat types across three administrative regions in NE Spain differing in the degree of human influence. For each patch, we calculated several variables reflecting habitat patch geometry (size and shape), landscape composition (distribution of land-cover categories) and landscape configuration (arrangement of patches). The last two groups of variables were calculated at five different spatial extents. Landscape composition was by far the most important group of variables associated with non-native species richness. Natural areas close to diverse and urban landscapes had a high number of non-native species while surrounding agricultural areas could buffer this effect. Regional human influence was also strongly associated with non-native species richness while habitat type was the least important factor. Differences in sensitivity of landscape variables across spatial extents proved relevant, with 100 m being the most influential extent for most variables. These results suggest that landscape characteristics should be considered for performing explicit spatial risk analyses of plant invasions. Consequently, the management of invaded habitats should focus not only at the stand scale but also at the highly influential neighbouring landscape. Prior to incorporate landscape characteristics into management decisions, sensitivity analyses should be taken into account to avoid inconsistent variables. 相似文献
8.
Land-cover and structural changes in a western Norwegian cultural landscape since 1865, based on an old cadastral map and a field survey 总被引:4,自引:2,他引:4
Liv Norunn Hamre Stein Tage Domaas Ingvild Austad Knut Rydgren 《Landscape Ecology》2007,22(10):1563-1574
Many studies of land-cover and structural changes in cultural landscapes have used historical maps as a source for information
about past land-cover. All transformations of historical maps onto modern coordinate systems are however burdened with difficulties
when it comes to accuracy. We show that a detailed land survey of the present landscape may enable transformation of an old
cadastral map directly onto the present terrain with very high accuracy. The detailed resulting map enabled us to locate remnants
of semi-natural grasslands and man-made structures with continuity from 1865 and to test hypotheses about relationships between
landscape changes and landscape characteristics. The main land-cover change 1865–2002 was decrease of arable fields, and addition
of three new land-cover classes: horticultural, orchard and abandoned areas. Of the 330 man-made structures present in 1865,
only 58 remained in 2002, while 63 new structures had been built after 1865. We found that semi-natural grasslands with continuity
since 1865 were situated on ground with significantly lower production capacity than mean 1865 production capacity. The man-made
structures with continuity since 1865 were also associated with areas with significantly lower production capacity than the
1865 mean, situated in significantly steeper terrain but not further from the hamlet. Our study illustrates the potential
of digitised and accurately transformed historical cadastral maps combined with detailed field surveys for analysis of land-cover
and structural changes in the cultural landscape. 相似文献
9.
Abel Bernadou Régis Céréghino Hugues Barcet Maud Combe Xavier Espadaler Vincent Fourcassié 《Landscape Ecology》2013,28(7):1387-1400
Of particular importance in shaping species assemblages is the spatial heterogeneity of the environment. The aim of our study was to investigate the influence of spatial heterogeneity and environmental complexity on the distribution of ant functional groups and species diversity along altitudinal gradients in a temperate ecosystem (Pyrenees Mountains). During three summers, we sampled 20 sites distributed across two Pyrenean valleys ranging in altitude from 1,009 to 2,339 m by using pitfall traps and hand collection. The environment around each sampling points was characterized by using both physical and land-cover variables. We then used a self-organizing map algorithm (SOM, neural network) to detect and characterize the relationship between the spatial distribution of ant functional groups, species diversity, and the variables measured. The use of SOM allowed us to reduce the apparent complexity of the environment to five clusters that highlighted two main gradients: an altitudinal gradient and a gradient of environmental closure. The composition of ant functional groups and species diversity changed along both of these gradients and was differently affected by environmental variables. The SOM also allowed us to validate the contours of most ant functional groups by highlighting the response of these groups to the environmental and land-cover variables. 相似文献
10.
Robert A. Long Therese M. Donovan Paula MacKay William J. Zielinski Jeffrey S. Buzas 《Landscape Ecology》2011,26(3):327-340
Terrestrial carnivores typically have large home ranges and exist at low population densities, thus presenting challenges
to wildlife researchers. We employed multiple, noninvasive survey methods—scat detection dogs, remote cameras, and hair snares—to
collect detection–nondetection data for elusive American black bears (Ursus americanus), fishers (Martes pennanti), and bobcats (Lynx rufus) throughout the rugged Vermont landscape. We analyzed these data using occupancy modeling that explicitly incorporated detectability
as well as habitat and landscape variables. For black bears, percentage of forested land within 5 km of survey sites was an
important positive predictor of occupancy, and percentage of human developed land within 5 km was a negative predictor. Although
the relationship was less clear for bobcats, occupancy appeared positively related to the percentage of both mixed forest
and forested wetland habitat within 1 km of survey sites. The relationship between specific covariates and fisher occupancy
was unclear, with no specific habitat or landscape variables directly related to occupancy. For all species, we used model
averaging to predict occurrence across the study area. Receiver operating characteristic (ROC) analyses of our black bear
and fisher models suggested that occupancy modeling efforts with data from noninvasive surveys could be useful for carnivore
conservation and management, as they provide insights into habitat use at the regional and landscape scale without requiring
capture or direct observation of study species. 相似文献
11.
Importance of Wetland Landscape Structure to Shorebirds Wintering in an Agricultural Valley 总被引:2,自引:1,他引:2
Only recently has the influence of landscape structure on habitat use been a research focus in wetland systems. During non-breeding
periods when food can be locally limited, wetland spatial pattern across a landscape may be of great importance in determining
wetland use. We studied the influence of landscape structure on abundances of wintering Dunlin (Calidris alpina) and Killdeer (Charadrius vociferus) observed on wetlands in the agricultural Willamette Valley of Oregon, USA, during two winters (1999–2000, 2000–2001) of
differing rainfall. We examined (1) shorebird use within a sample of 100 km2 regions differing in landscape structure (hectares of shorebird habitat [wet, unvegetated]) and (2) use of sites differing
in landscape context (area of shorebird habitat within a species-defined radius). For use of sites, we also assessed the influence
of two local characteristics: percent of soil exposed and area of wet habitat. We analyzed data using linear regression and
information-theoretic modeling. During the dry winter (2000–2001), Dunlin were attracted to regions with more wetland habitat
and their abundances at sites increased with greater area of shorebird habitat within both the site and the surrounding landscape.
In contrast, Dunlin abundances at sites were related to availability of habitat at only a local scale during the wet winter
(1999–2000). Regional habitat availability was of little importance in predicting Killdeer distributions, and Killdeer site
use appeared unrelated to habitat distributions at both landscape and local scales. Results suggest prioritizing sites for
conservation that are located in areas with high wetland coverage. 相似文献
12.
Context
In agricultural landscapes, riparian forests are used as a management tool to protect stream ecosystems from agricultural activities. However, the ability of managers to target stream protection actions is limited by incomplete knowledge of scale-specific effects of agriculture in riparian corridor and catchment areas.Objectives
We evaluated scale-specific effects of agricultural cover in riparian corridor and catchment areas on stream benthic macroinvertebrate (BMI) communities to develop cover targets for agricultural landscapes.Methods
Sixty-eight streams assigned to three experimental treatments (Forested Riparian, Agricultural Riparian, Agricultural Catchment) were sampled for BMIs. Ordination and segmented regression were used to assess impacts of agriculture on BMI communities and detect thresholds for BMI community metrics.Results
BMI communities were not associated with catchment agricultural cover where the riparian corridor was forested, but were associated with variation in catchment agriculture where riparian forests had been converted to agriculture. Trait-based metrics showed threshold responses at greater than 70% agricultural cover in the catchment. Increasing agriculture in the riparian corridor was associated with less diverse and more tolerant BMI communities. Eight metrics exhibited threshold responses ranging from 45 to 75% agriculture in the riparian corridor.Conclusions
Riparian forest effectively buffered streams from agricultural activity even where catchment agriculture exceeds 80%. We recommend managers prioritize protection of forested riparian corridors and that restore riparian corridors where agricultural cover is near identified thresholds be a secondary priority. Adoption of catchment management actions should be effective where the riparian corridor has been converted to agriculture.13.
Associations between soil carbon and ecological landscape variables at escalating spatial scales in Florida,USA 总被引:1,自引:1,他引:0
The spatial distribution of soil carbon (C) is controlled by ecological processes that evolve and interact over a range of
spatial scales across the landscape. The relationships between hydrologic and biotic processes and soil C patterns and spatial
behavior are still poorly understood. Our objectives were to (i) identify the appropriate spatial scale to observe soil total
C (TC) in a subtropical landscape with pronounced hydrologic and biotic variation, and (ii) investigate the spatial behavior
and relationships between TC and ecological landscape variables which aggregate various hydrologic and biotic processes. The
study was conducted in Florida, USA, characterized by extreme hydrologic (poorly to excessively drained soils), and vegetation/land
use gradients ranging from natural uplands and wetlands to intensively managed forest, agricultural, and urban systems. We
used semivariogram and landscape indices to compare the spatial dependence structures of TC and 19 ecological landscape variables,
identifying similarities and establishing pattern–process relationships. Soil, hydrologic, and biotic ecological variables
mirrored the spatial behavior of TC at fine (few kilometers), and coarse (hundreds of kilometers) spatial scales. Specifically,
soil available water capacity resembled the spatial dependence structure of TC at escalating scales, supporting a multi-scale
soil hydrology-soil C process–pattern relationship in Florida. Our findings suggest two appropriate scales to observe TC,
one at a short range (autocorrelation range of 5.6 km), representing local soil-landscape variation, and another at a longer
range (119 km), accounting for regional variation. Moreover, our results provide further guidance to measure ecological variables
influencing C dynamics. 相似文献
14.
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
15.
Understanding how organisms respond to landscape heterogeneity is foundational to landscape ecology. We characterized seasonal
scales of movement of white-tailed deer (Odocoileus viginianus) in an agricultural–forest matrix using first-passage time analysis (FPT) for 62 GPS-collared individuals. We investigated
whether those scales were driven by demographic or landscape features. We found FPT for each individual across all seasons
was typically dominated by a peak in variance of FPT/area at scales (radii) from 425 to 1,675 m. These peaks occurred at scales
consistent with seasonal space use. We observed additional lower magnitude peaks at larger scales (3,000–6,000 m) and small
scales (25–150 m). Peaks at larger scales were associated with seasonal migrations and dispersal events. Small scale peaks
may represent resting or foraging behavior. Female movements were organized at smaller scales than males in the spring/summer
season. Models relating landscape features to movement scales suggest that deer perceive and move within the landscape differently
as the roles of dominant land-cover types shift seasonally. During winter, configuration (interspersion/juxtaposition) of
land-cover types is more important to deer than during spring/summer and fall. During spring/summer and fall, movement behavior
may be dictated by reproductive and harvest activities. 相似文献
16.
With expansion of urban areas worldwide, migrating songbirds increasingly encounter fragmented landscapes where habitat patches
are embedded in an urban matrix, yet how migrating birds respond to urbanization is poorly understood. Our research evaluated
the relative importance of patch-level effects and body condition to movement behaviour of songbirds during migratory stopover
within an urban landscape. We experimentally relocated 91 migrant Swainson’s thrushes (Catharus ustulatus) fitted with 0.66 g radio-transmitters to seven forest patches that differed in area (0.7–38.4 ha) and degree of urbanization
within central Ohio, USA, May 2004–2007. Fine-scale movement rate of thrushes (n = 55) did not differ among urban forest sites, but birds in low energetic condition moved at higher rates, indicating an
energetically mediated influence on movement behaviour. In larger sites, Swainson’s thrushes (n = 59) had greater coarse-level movement during the first 3 days and utilized areas farther from forest edge, indicating stronger
influence by patch-level factors. Thrushes exhibited strong site tenacity, with only five individuals (7%) leaving release
patches prior to migratory departure. Movement outside the release patch only occurred at the smallest forest patches (0.7
and 4.5 ha), suggesting that these sites were too small to meet needs of some individuals. Swainson’s thrushes exhibited edge
avoidance and apparent area sensitivity within urban forest patches during stopover, implying that conservation of larger
patches within urban and other fragmented landscapes may benefit this species and other migrant forest birds. 相似文献
17.
Regional land-cover change affects biodiversity, hydrology, and biogeochemical cycles at local, watershed, and landscape scales.
Developing countries are experiencing rapid land cover change, but assessment is often restricted by limited financial resources,
accessibility, and historical data. The assessment of regional land cover patterns is often the first step in developing conservation
and management plans. This study used remotely sensed land cover and topographic data (Landsat and Shuttle Radar Topography
Mission), supervised classification techniques, and spectral mixture analysis to characterize current landscape patterns and
quantify land cover change from 1985 to 2003 in the Altiplano (2535–4671 m) and Intermediate Valley (Mountain) (1491–4623 m)
physiographic zones in the Southeastern Bolivian Andes. Current land cover was mapped into six classes with an overall accuracy
of 88% using traditional classification techniques and limited field data. The land cover change analysis showed that extensive
deforestation, desertification, and agricultural expansion at a regional scale occurred in the last 20 years (17.3% of the
Mountain Zone and 7.2% of the Altiplano). Spectral mixture analysis (SMA) indicated that communal rangeland degradation has
also occurred, with increases in soil and non-photosynthetic vegetation fractions in most cover classes. SMA also identified
local areas with intensive management activities that are changing differently from the overall region (e.g., localized areas
of increased green vegetation). This indicates that actions of local communities, governments, and environmental managers
can moderate the potentially severe future changes implied by the results of this study. 相似文献
18.
We studied the effects of anthropogenic edges on predation and parasitism of forest bird nests in an agriculturally fragmented
landscape and a continuously forested landscape in Ontario, Canada. Nesting data were collected at 1937 nests across 10 species
in the fragmented landscape from 2002–2008, and 464 nests across 4 species in the continuously forested landscape from 2006–2008.
Brood parasitism only occurred in the fragmented landscape, and was positively related to the proportion of rural grassland
and row crop habitats within 500-m of nests. Daily nest survival was negatively related to the density of roads within 500-m
of nests in the fragmented landscape, but was not influenced by distance to anthropogenic edge in either landscape. Predation
rates were higher in the fragmented landscape for Ovenbird and Rose-breasted Grosbeak nests, but did not differ between landscapes
for Veery and American Redstart nests. Uniformly high predation in the fragmented landscape may be a result of (1) matrix
predators that penetrate deep (>300 m) into the forest interior, or (2) the additive effect of forest-dependent and matrix-associated
predators that results in high predation pressure in both edge and interior habitats. Further research focused on the identification
of nest predators, their population dynamics, and habitat use is required to understand the underlying mechanisms leading
to uniformly high nest predation in fragmented landscapes. 相似文献
19.
The rapid expansion of the world’s urban population is a major driver of contemporary landscape change and ecosystem modification.
Urbanisation destroys, degrades and fragments native ecosystems, replacing them with a heterogeneous matrix of urban development,
parks, roads, and isolated remnant fragments of varying size and quality. This presents a major challenge for biodiversity
conservation within urban areas. To make spatially explicit decisions about urban biodiversity conservation actions, urban
planners and managers need to be able to separate the relative influence of landscape composition and configuration from patch
and local (site)-scale variables for a range of fauna species. We address this problem using a hierarchical landscape approach
for native, terrestrial reptiles and small mammals living in a fragmented semi-urban landscape of Brisbane, Australia. Generalised
linear modelling and hierarchical partitioning analysis were applied to quantify the relative influence of landscape composition
and configuration, patch size and shape, and local habitat composition and structure on the species’ richness of mammal and
reptile assemblages. Landscape structure (composition and configuration) and local-scale habitat structure variables were
found to be most important for influencing reptile and mammal assemblages, although the relative importance of specific variables
differed between reptile and mammal assemblages. These findings highlight the importance of considering landscape composition
and configuration in addition to local habitat elements when planning and/or managing for the conservation of native, terrestrial
fauna diversity in urban landscapes. 相似文献
20.
Spatial weighting of land use and temporal weighting of antecedent discharge improves prediction of stream condition 总被引:1,自引:0,他引:1
Land management to protect streams requires knowing which parts of the landscape most strongly influence stream condition. Understanding how flow through landscapes and along streams affects such land-use impacts requires knowing the period of antecedent discharge that most strongly influences condition. Both considerations require determination of optimal weighting schemes for predictors of stream condition. We calculated forest cover weighted by flow-path distance to 572 urban, peri-urban, and rural sites—in the Melbourne, Australia, region—sampled for macroinvertebrates, and antecedent discharge weighted by time preceding each of 1,723 samples. Using mixed linear models that accounted for spatial dependence, we aimed to determine the weighting curve shape and length that best predicted macroinvertebrate assemblage composition. The best model was a function of mean annual discharge, weighted forest cover, weighted imperviousness, weighted antecedent discharge, and their interactions. Optimal weightings were exponential—half-decay distance 35 m overland (plausible range 26–50 m), and 1.0 km in-stream (0.75–1.3 km) for forest cover—, and linear over ≥4 year for antecedent discharge. Model plausibility was more affected by weighting distance than the shape of the weighting function. Regardless of weighting curve shape, riparian forest effects on macroinvertebrate assemblages are strongest within 101–102 m from the stream, and 103 m upstream. Although exponential weightings are only marginally more plausible, they are the most realistic representation of physical processes. While our conclusions should not be interpreted as recommendations for buffer widths, they provide valuable insight into the scales of influence in the region and could be used to inform management decisions. 相似文献