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1.
Landscape influences on stream biotic integrity assessed at multiple spatial scales 总被引:31,自引:0,他引:31
The biological integrity of stream ecosystems depends critically on human activities that affect land use/cover along stream
margins and possibly throughout the catchment. We evaluated stream condition using an Index of Biotic Integrity (IBI) and
a habitat index (HI), and compared these measures to landscape and riparian conditions assessed at different spatial scales
in a largely agricultural Midwestern watershed. Our goal was to determine whether land use/cover was an effective predictor
of stream integrity, and if so, at what spatial scale. Twenty-three sites in first-through third-order headwater streams were
surveyed by electrofishing and site IBIs were calculated based on ten metrics of the fish collection. Habitat features were
characterized through field observation, and site HIs calculated from nine instream and bank metrics. Field surveys, aerial
photograph interpretation, and geographic information system (GIS) analyses provided assessments of forested land and other
vegetation covers at the local, reach, and regional (catchment) scales.
The range of conditions among the 23 sites varied from poor to very good based on IBI and HI scores, and habitat and fish
assemblage measures were highly correlated. Stream biotic integrity and habitat quality were negatively correlated with the
extent of agriculture and positively correlated with extent of wetlands and forest. Correlations were strongest at the catchment
scale (IBI with % area as agriculture, r2=0.50, HI with agriculture, r2=0.76), and tended to become weak and non-significant at local scales. Local riparian vegetation was a weak secondary predictor
of stream integrity. In this watershed, regional land use is the primary determinant of stream conditions, able to overwhelm
the ability of local site vegetation to support high-quality habitat and biotic communities. 相似文献
2.
Carlos Ovalle Alejandro Del Pozo Miguel A. Casado Belén Acosta José M. de Miguel 《Landscape Ecology》2006,21(4):585-594
The current land use system in the anthropogenic savannas (Espinales) of the Mediterranean climate region of Chile, has resulted in considerable heterogeneity at the landscape level which is
associated with different covers of the legume tree, Acacia caven. The effects of landscape heterogeneity on the diversity and productivity of herbaceous plant communities were studied in
29 plots of 1000 m2, with a wide range of woody cover. A detrended correspondence analysis of the species × plots matrix explained 73% of the
total variation and revealed the existence of two trends of variation in floristic composition: one associated with physiographic
position (hillsides and flatlands) and the other related to the number of years since the last cutting, or coppicing, of A. caven. Despite the great majority of the original herbaceous species having disappeared as a result of the prevailing land use
system, some native species have been able to survive especially on hillside areas with low grazing intensity. Woody cover
was a good indicator of spatial heterogeneity and land use history. It was also correlated with stocking rate, above-ground
biomass of herbaceous vegetation, and soil fertility (organic matter, nitrogen and phosphorus concentration), both on hillsides
and flatlands. The relationship between woody cover and herbaceous plant species richness was significant and unimodal in
flat land areas, and linear, and marginally significant, on hillsides. The consequences of land use changes on the conservation
of the ecological and productive values of grasslands are analyzed. 相似文献
3.
Melissa B. Youngquist Kentaro Inoue David J. Berg Michelle D. Boone 《Landscape Ecology》2017,32(1):147-162
Context
Species distributions are a function of an individual’s ability to disperse to and colonize habitat patches. These processes depend upon landscape configuration and composition.Objectives
Using Blanchard’s cricket frogs (Acris blanchardi), we assessed which land cover types were predictive of (1) presence at three spatial scales (pond-shed, 500 and 2500 m) and (2) genetic structure. We predicted that forested, urban, and road land covers would negatively affect cricket frogs. We also predicted that agricultural, field, and aquatic land covers would positively affect cricket frogs.Methods
We surveyed for cricket frogs at 28 sites in southwestern Ohio, USA to determine presence across different habitats and analyze genetic structure among populations. For our first objective, we examined if land use (crop, field, forest, and urban habitat) and landscape features (ponds, streams, and roads) explained presence; for our second objective, we assessed whether these land cover types explained genetic distance between populations.Results
Land cover did not have a strong influence on cricket frog presence. However, multiple competing models suggested effects of roads, streams, and land use. We found genetic structuring: populations were grouped into five major clusters and nine finer-scale clusters. Highways were predictive of increased genetic distance.Conclusions
By combining a focal-patch study with landscape genetics, our study suggests that major roads and waterways are key features affecting species distributions in agricultural landscapes. We demonstrate that cricket frogs may respond to landscape features at larger spatial scales, and that presence and movement may be affected by different environmental factors.4.
Louis R. Iverson 《Landscape Ecology》1988,2(1):45-61
The Illinois Geographic Information System was used to compare the soil and landscape attributes of the State with its historic vegetation, current land use, and patterns of land-use change over the past 160 years. Patch structural characteristics among land types in four geographic zones were also compared. The assessment of patch characteristics revealed a highly modified State with most land patches controlled by human influences and relatively few by topographic and hydrologic features. Correlation and regression analyses determined the relationships of land type and abundance within each of 50 general soil associations to properties of the soil associations - typically slope, texture, organic matter, productivity index, and available waterholding capacity. The distribution of the historic vegetation of the State and its current deciduous forests and nonforested wetlands related moderately (r2 0.44) to various landscape attributes. Urban and other highly modified land types were less closely related. 相似文献
5.
We present a parametric model for estimating the areas within watersheds whose land use best predicts indicators of stream
ecological condition. We regress a stream response variable on the distance-weighted proportion of watershed area that has
a specific land use, such as agriculture. Distance weighting functions model the declining influence of landscape elements
as a function of their flowpath distances, first to the stream channel (to-stream distance), and then down the channel to
the location at which stream condition was sampled (in-stream distance). Model parameters specify different distance scales
over which to-stream and in-stream influences decline. As an example, we predict an index of biotic integrity (IBI) for the
fish communities in 50 small streams of the Willamette Basin of Oregon, USA, from distance-weighted proportions of agricultural
or urban land use in their watersheds. The weighting functions of best-fitting models (R
2 = 0.57) represent landscape influence on IBI as extending upstream tens of kilometers along the stream channel network, while
declining nearly to zero beyond a distance of 30 m from the channel. Our example shows how parametric distance weighting can
identify the distance scales, and hence the approximate areas within watersheds, for which land use is most strongly associated
with a stream response variable. In addition, distance-weighting parameters offer a simple and direct language for comparing
the scales of landscape influence on streams across different land uses and stream ecosystem components. 相似文献
6.
Ixchel M. Hernandez Craig D. Stanley Xin Zhao 《International Journal of Fruit Science》2016,16(1):103-112
During strawberry (Fragaria × ananassa) freeze protection, the standard practice is applying sprinkler irrigation on plant canopies to prevent and reduce freezing damage. This method is highly inefficient because it uses large volumes of water. The overall goal of this study was to compare the effects of freeze protection methods on water savings, and growth and fruit weight of strawberry. Treatments consisted of the following: sprinkler heads delivering 17 L?min–1, sprinkler heads delivering 13 L?min–1, light-weight row covers (21 g?m–2) on the crop canopy, light-weight row covers on 60-cm-high mini-tunnel hoops, heavy-weight row covers (31 g?m–2) on the crop canopy, heavy-weight row covers on 60-cm-high mini-tunnel hoops, and foliar application of a polymer (Desikote). There were eight freezing and near freezing nights (≤1.1 °C) at the experimental site during both seasons with a minimum air temperature of –2.8 °C. Minimum temperature inside the row covers ranged between 0.6 to 4.4 °C at the canopy level. There were significant treatment effects on early and total marketable fruit weights. The highest early marketable fruit weight was found in plots protected with light-weight row covers with hoops, heavy-weight row covers on canopy, and foliar polymer, ranging between 5.0 to 5.5 t?ha–1. For total marketable fruit weight, using non-irrigation methods resulted in the highest fruit weight with 23.0 t?ha–1. In conclusion, data showed that using non-irrigation techniques provided satisfactory freeze protection under the evaluated conditions and increased total marketable fruit weight, possibly due to reduced injury of fruits and flowers when using alternative techniques. 相似文献
7.
Empirical relationships between land use/cover and estuarine condition in the Northeastern United States 总被引:1,自引:0,他引:1
Wilfrid Rodriguez Peter V. August Yeqiao Wang John F. Paul Arthur Gold Norman Rubinstein 《Landscape Ecology》2007,22(3):403-417
Land–water interactions were examined in three regions in the Virginian Biogeographic Province; the southern shore of Cape
Cod, Massachusetts; the Hudson/Raritan region of New York; and the eastern shore of the Delmarva (Delaware/Maryland/Virginia)
Peninsula. Cumulative distribution functions were used to evaluate similarity in environmental condition among estuaries.
Spatial-setting variables (location in a river, coastal lagoon, or in open waters) were associated with variation for some
measures of estuarine condition. Patterns of coastal urban and agriculture gradients were measured and their relationship
with indicators of estuarine condition was modeled statistically. When estuaries were pooled, the highest variation explained
by spatial-setting variables was found for dissolved oxygen (DO, R
2 = 0.44) and salinity (R
2 = 0.58), with DO decreasing in river locations and salinity decreasing with rainfall and sampling locations near rivers.
The explanatory power for the other indicator variables was low and varied from 6% to 27%. Rainfall explained some of the
variation (R
2 = 0.23) in total suspended solids. Moderate (0.4 < | r | < 0.7) to strong (| r | ≥ 0.7) linear associations were found between total urban area and measures of estuarine condition. Within regions, total
urban area was positively associated with Silver (r = 0.59), Cadmium (r = 0.65), and Mercury (r = 0.47) in Cape Cod, and inversely related to DO (r = −0.65) in the Hudson/Raritan region. No associations were found in the Delmarva Peninsula study area. Total area of agriculture
showed a moderate association with Arsenic in Cape Cod, but no other associations were found in the other two regions. Our
analyses show a measurable impact of urban land use on coastal ecosystem condition over large areas of the northeastern United
States. This pattern was most evident when many different landscapes were considered simultaneously. The relationship between
urban development and estuarine condition were weaker within the individual regions studied. The use of land use/cover models
for predicting estuarine condition is a challenging task that warrants enhancements in the type, quantity, and quality of
data to improve our ability to discern relationships between anthropogenic activities on land and the condition of coastal
environments. 相似文献
8.
The increase in hailstorms, possibly due to climate change, has led to installation of hailnets in fruit orchards worldwide. This is associated with poorer fruit quality, particularly fruit colouration, which is determined by the light conditions viz diminishing light intensities and shorter day length in the autumn. To overcome these adverse effects of hailnets, five materials were examined as possible ground covers as to their light reflection and the subsequent effect on fruit quality including fruit colouration, using a 9-year-old apple orchard cv. ‘Gala Mondial’ on M9 under black hailnet near Bonn. The ground covers included the woven white plastic ExtendayR/Daybright™, the kaolin-coated, bio-degradable paper UniSet O™ and the aluminium-coated plastic Mylar™ and Svensson ILS Alu™; the latter is a white plastic interwoven with aluminium strips used as energy saving screen in greenhouses. The ground covers were spread in the alleyways 4–5 weeks before anticipated harvest; adjacent uncovered grass strips under the hailnet served as control. Light reflection, measured perpendicular at 1 m height in the alleyways at the time of fruit colouration, was 79–80% by ExtendayR/Daybright™, 75% by UniSet O™, 68% by Mylar™ and 58% by Svensson Alu ILS™. Apple fruit with any of the reflective ground covers ripened 2–3 days earlier without affecting internal fruit quality and sugar as indicative of taste. The reflective ground covers under black hailnet improved the proportion of well-coloured class I fruit relative to the control (uncovered grass) by an averaged 9%. Economic analysis showed that ExtendayR, with an expected lifetime of ten years (based on 4–6 weeks spread time per year) under hail nets in North-Western Europe, scored best based on 45 t ha−1 yield in cv. ‘Gala Mondial’ and 0.40 € kg−1 farm-gate price, resulting in 200 € ha−1 net return. Manual labour for spreading and retrieving the ground covers had the major share of the overall gross cost and offers scope for improvement by mechanisation. 相似文献
9.
The conversion of forests and farmlands to human settlements has negative impacts on many native species, but also provides
resources that some species are able to exploit. American Crows (Corvus brachyrhynchos), one such exploiter, create concern due to their impact as nest predators, disease hosts, and cultural harbingers of evil.
We used various measures of crow abundance and resource use to determine crows’ response to features of anthropogenic landscapes
in the Puget Sound region of the United States. We examined land cover and land use composition at three spatial scales: study
sites (up to 208 ha), crow home ranges within sites (18.1 ha), and local land cover (400 m2). At the study site and within-site scales crow abundance was strongly correlated with land cover providing anthropogenic
resources. In particular, crows were associated with the amount of ‘maintained forest’ cover, and were more likely to use
grass and shrub cover than forest or bare soil cover. Although crows did not show a generalized response to an edge variable,
they exhibited greater use of patchy habitat created by human settlements than of native forests. Radio-tagged territorial
adults used resources within their home ranges relatively evenly, suggesting resource selection had occurred at a larger spatial
scale. The land conversion pattern of new suburban and exurban settlements creates the mix of impervious surfaces and maintained
vegetation that crows use, and in our study area crow populations are expected to continue to increase.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
The accuracy of land cover-based wetland assessments is influenced by landscape extent 总被引:2,自引:0,他引:2
Rebecca C. Rooney Suzanne E. Bayley Irena F. Creed Matthew J. Wilson 《Landscape Ecology》2012,27(9):1321-1335
Widespread degradation of wetlands has motivated the development of tools to evaluate wetland condition. The application of field-based tools over large regions can be prohibitively expensive; however, land cover data may provide a surrogate for intensive assessments, enabling rapid and cost-effective evaluation of wetlands throughout whole regions. Our goal was to determine if land cover data could be used to estimate the biotic integrity of wetlands in Alberta??s Beaverhills watershed. Biotic integrity was measured using both plant- and bird-based indices of biotic integrity (IBIs) in 45 wetlands. Land cover data were extracted from seven nested landscape extents (100?C3,000?m radii) and used to model IBI scores. Strong, significant predictions of IBI scores were achieved using land cover data from every spatial extent, even after factoring out the influence of location to address the spatial autocorrelation of land cover classes. Plant-based IBI scores were best predicted using data from 100?m buffers and bird-based IBI scores were best predicted using data extracted from 500?m buffers. Road cover or density and measures of the proportion of disturbed land were consistent predictors of IBI score, suggesting their universal importance to plant and bird communities. Simplified models using the proportion of undisturbed land were less accurate than more detailed models (reductions in r 2 of 0.31?C0.32). Regardless of the level of detail in land cover classification, our results emphasize the need to optimize landscape extent for the taxonomic group of interest: an issue that is typically poorly articulated in studies reporting on the development of GIS-based assessment methods. Our results also highlight the need to calibrate models in test areas before scaling up, to ensure predictive accuracy. 相似文献
11.
Sandra C. Margriter Gregory L. Bruland Gregory M. Kudray Christopher A. Lepczyk 《Landscape Ecology》2014,29(3):517-528
Although wetland condition assessment procedures have been developed, validated, and calibrated in the continental United States, they have not yet been fully developed or field-tested for wetlands in Hawai‘i. In order to address the need for comprehensive assessment methods for Hawaiian coastal wetlands, our research compared three indicators of landscape condition (landscape development intensity, road density, and forest cover) with wetland condition as measured by rapid assessment methods (RAM) and detailed field data collected on soil and water quality. We predicted that wetlands located in the least developed landscapes would have more nutrient rich soils, yet lower nutrient levels in the surface water, and would receive the highest rapid assessment scores. The hypotheses of our study were generally supported. However, while the correlations between landscape variables and δ15N isotopes and CRAM scores were relatively strong, the correlations between the landscape indicators and the other Level II and III field indicators were not very strong. These results suggest that further calibration and refinement of metrics is needed in order to more accurately assess the condition of Hawaiian coastal wetlands. A more detailed land use map, in addition to more comprehensive assessments of wetland water quality and biotic integrity would likely improve the relationships between indicators of landscape condition and wetland condition. Nonetheless, our research demonstrated that landscape analysis at larger scales (1,000 m buffers and watersheds) could provide managers with valuable information on how regional stressors may be affecting wetland water quality (measured as δ15N in plant tissue) as well as overall wetland condition (RAM scores). 相似文献
12.
Dividing regions into manageable landscape units presents special problems in landscape ecology and land management. Ideally,
a landscape should be large enough to capture a broad range of vegetation, environmental and disturbance dynamics, but small
enough to be useful for focused management objectives. The purpose of this study was to determine the optimal landscape size
to summarize ecological processes for two large land areas in the southwestern United States. We used a vegetation and disturbance
dynamics model, LANDSUMv4, to simulate a set of nine scenarios involving systematically varied topography, map resolution,
and model parameterizations of fire size and fire frequency. Spatial input data were supplied by the LANDscape FIRE Management
Planning System (LANDFIRE) prototype project, an effort that will provide comprehensive and scientifically credible mid-scale
data to support the National Fire Plan. We analyzed output from 2,000 year simulations to determine the thresholds of landscape
condition based on the variability of burned area and dominant vegetation coverage. Results show that optimal landscape extent
using burned area variability is approximately 100 km2 depending on topography, map resolution, and model parameterization. Variability of dominant vegetation area is generally
higher and the optimal landscape sizes are larger in comparison to those features determined from burned area. Using the LANDFIRE
project as a case study, we determined landscape size and map resolution for a large mapping project, and showed that optimal
landscape size depends upon geographical, ecological, and management context.
This paper was written and prepared by U.S. Government employees on official time, and therefore is in the public domain and
not subject to copyright. The use of trade or firm names in this paper is for reader information and does not imply endorsement
by the U.S. Department of Agriculture of any product or service. 相似文献
13.
The effect of greenery on traffic noise mitigation has been extensively studied on the level of single plants, green walls, berms and hedges, but not considering whole sample areas within the cities. Therefore, the aim of this paper is to investigate the relationship between features of urban morphology related to green spaces, roads or buildings and traffic noise distribution in urban areas. The analysis was applied in eight UK cities with different historical and architectural background, following two different settlement forms (radial, linear). In each city a 30 km2 grid was defined and three different levels of approach were considered (macro-scale, meso-scale, micro-scale). The first level regarded the eight cities as single entities, while in the second one every single tile of the applied grid was investigated in two different cities. In the third level only the eight city centres were analyzed. Statistical analysis was used combined with GIS tools. In total 18 variables were constructed and tested for possible relationships with noise levels (Lden). It was found that in spite of the fact that each city has its own dynamic and form, features of urban morphology were related to traffic noise levels to a different extent at each scale. At the macro-scale, the green space pattern was related to the structure of the city as well as the traffic noise levels in combination with the rest of the morphological parameters. At the meso-scale, an increase in internal road connectivity contributed to higher traffic noise. Green space variables explained part of the variance in traffic prediction models. Finally, at the micro-scale, it was also proved that different areas can have the same building coverage but different noise levels. Therefore, these indexes could be profiled and used as an “a priori” tool for urban sound planning. 相似文献
14.
Olga Viedma 《Landscape Ecology》2008,23(6):657-672
Mediterranean landscapes are dynamic systems that undergo temporal changes in composition and structure in response to disturbances,
such as fire. Neither landscape patterns nor driving factors that affect them are evenly distributed in space. Accordingly,
disturbances and biophysical factors interact in space through time. The aim of this paper is to assess the relative influence
of topography and fire on the landscape patterns of a large forested area located in Sierra de Gredos (Central Spain) through
time. A series of Landsat MSS images from 1975 to 1990, and a digital elevation model (DEM) were used to map fires, assess
topographical complexity and evaluate changes in landscape composition and structure. Functional regions across the entire
landscape were identified using different classification criteria (i.e., percentage burned area and topographic properties)
to model topographic and fire impacts at regional scales. A canonical variance partition method, with a time series split-plot
design, quantified the relative influence and co-variation of topography and fire on land cover patterns through time. Main
results indicated that analyzing portions of the landscape under similar environmental conditions and fire histories, the
effects of different fire regimes on the spatio-temporal dynamics of main land covers can be highlighted. However, the impact
of fire on landscape patterns was high variable among regions due to the different regeneration abilities of main land covers,
the topographic constraints and the fire histories of each region. Hence, broad patterns of fire related variance and co-variation
with topography emerged across the entire area due to the different conditions of each landscape portion in which this large
Mediterranean landscape was divided.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
16.
Judith A. Simon Joel W. Snodgrass Ryan E. Casey Donald W. Sparling 《Landscape Ecology》2009,24(3):361-373
Many amphibian species rely on both aquatic and terrestrial habitats to complete their life cycles. Therefore, processes operating
both within the aquatic breeding habitat, and in the surrounding uplands may influence species distributions and community
composition. Moreover, changes in land use adjacent to breeding site may degrade aquatic habitats. To assess land use effects
on pond-breeding amphibian assemblages, we investigated relationships between land use, breeding habitat conditions, and breeding
amphibian use of constructed wetlands in urban environments of the Baltimore metropolitan area, USA. Forest and impervious
surface associations with species richness and occurrence occurred at spatial scales ranging from 50 to 1,000 m, with strongest
relationships at 500 m. Forest and impervious surface cover within 1,000 m of ponds were also related to water and sediment
quality, which in turn were capable of explaining a proportion of the observed variation in species richness and occurrence.
Taken together, our results suggest that forest and other land covers within relatively proximal distances to ponds (i.e.,
within 50–1,000 m) may be influencing species richness directly via the provisioning of upland habitat, and indirectly via
influences on within pond habitat quality.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Yongping Cai Guoqing Li Jingquan Nie Yi Lin Fan Nie Jinyun Zhang Yiliu Xu 《Scientia Horticulturae》2010
Pear stone cell content is one of key determinants of fruit quality. Stone cells form by the deposition of lignin on primary cell walls, following secondary thickening of cell walls. Studies of the structure and metabolic pathway of pear lignin are rare. Stone cell and lignin content in the pulp of Pyrus bretschneideri cv. Dangshan Su were determined during fruit development. Lignin was extracted, purified and analyzed by ultraviolet (UV) light, Fourier-transform infrared (FTIR) spectroscopy and 1H nuclear magnetic resonance (1H NMR) spectroscopy. Intermediates of lignin biosynthesis were detected by high-performance liquid chromatography (HPLC). The results show that lignin content increases initially and decreases afterwards during fruit development, peaking twice at day 47 and day 63 after flowering. The lignin peaks precede both peaks of stone cell content (day 51 after flowering) and at the point at which sclereids reach their maximum diameter (day 67 after flowering). The milled wood lignin in pulp was identified as guaiacyl-syringyl-lignin by spectroscopic analyses. In the FTIR spectra, the peak intensity ratio of A1269/A1227 was 1.25. HPLC analyses detected cinnamic acid and p-coumaric acid, but not caffeic acid or ferulic acid. In conclusion, during pear fruit development, lignin is first biosynthesized, and subsequently deposited on cell walls to form stone cells and sclereids. The biosynthesis of guaiacyl-syringyl- lignin in pear pulp may involve a phenylpropane-type metabolic pathway from phenylalanine to cinnamic acid and acyl-CoA ester, as pear pulp lignin contains more guaiacyl units than syringyl units. 相似文献
18.
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
19.
Quantifying the spatial relationship between bird species’ distributions and landscape feature boundaries in southern Ontario, Canada 总被引:2,自引:1,他引:1
Aleksandra E. Polakowska Marie-Josée Fortin Andrew Couturier 《Landscape Ecology》2012,27(10):1481-1493
Understanding what features of the landscape affect species distribution is critical to effectively implement conservation strategies. This study investigates how a boundary analysis framework can be used to characterize the spatial association between boundaries (i.e., spatial locations of high rates of change) in bird species?? distributions and landscape features at the regional scale. The study area covers 92,000?km2 in southern Ontario (Canada) and extends from the Great Lakes-St. Lawrence biome to the southern Canadian Shield biome. Landcover composition was derived from Ontario Land Cover data (1991?C1998; 7 types) and elevation data were derived from the Canada3D digital elevation model. Bird distributions were estimated using indicator kriging based on point counts obtained from the Ontario Breeding Bird Atlas data (2001?C2005; 60 species). Boundaries were delineated for both data types using a 10?×?10?km cell resolution. Spatial boundary overlap statistics were used to quantify the spatial relationship between landscape features and bird boundaries and tested using a randomization procedure. There was significant positive association and spatial overlap between delineated landscape feature boundaries and bird boundaries. The number of spatially overlapping cells between the two boundary types was 67 out of 164 (41?%) and 76?% of cells were within 11.42?km of each other. These results were statistically significant (P?<?0.001) and suggest a strong spatial relationship between high rates of change in landscape features and bird species?? distributions at the regional scale. A boundary analysis framework could be used to identify boundary shifts in response to climate change and anticipate changes in species distributions. 相似文献
20.
Trade-offs between tree cover, carbon storage and floristic biodiversity in reforesting landscapes 总被引:3,自引:2,他引:1
Jaclyn M. Hall Tracy Van Holt Amy E. Daniels Vincent Balthazar Eric F. Lambin 《Landscape Ecology》2012,27(8):1135-1147
This study explores the relationships between an increase in tree cover area (i.e., natural and planted-tree land covers) and changes in forest carbon storage and the potential of a landscape to provide habitat for native floristic biodiversity. Four areas experiencing an increase in tree cover were analyzed. We developed a metric estimating the potential to support native biodiversity based on tree cover type (plantation or natural forests) and the landscape pattern of natural and anthropogenic land covers. We used published estimates for forest and plantation carbon stocks for each region. Focus regions in northwestern Costa Rica, northern Vietnam, southern Chile and highland Ecuador all showed an increase in tree cover area of 390?%, 260?%, 123?% and 418?%, respectively. Landscapes experiencing increases in natural secondary forest also experienced an increase in carbon stored above and below ground, and in the potential to support native floristic biodiversity. Study landscapes in Chile and Ecuador experiencing an expansion of exotic plantations saw their carbon stock decrease along with their potential to support native floristic biodiversity. This study shows that an increase in forest area does not necessarily imply an increased provision of ecosystem services when landscapes are reforesting with monoculture plantations of exotic tree species. Changes in the support of native biodiversity and the carbon stored in pulp rotation plantations, along with other ecosystem services, should be fully considered before implementing reforestation projects. 相似文献