共查询到20条相似文献,搜索用时 15 毫秒
1.
Charlotte E. Gonzalez-Abraham Volker C. Radeloff Roger B. Hammer Todd J. Hawbaker Susan I. Stewart Murray K. Clayton 《Landscape Ecology》2007,22(2):217-230
Housing growth is prevalent in rural areas in the United States and landscape fragmentation is one of its many effects. Since
the 1930s, rural sprawl has been increasing in areas rich in recreational amenities. The question is how housing growth has
affected landscape fragmentation. We thus tested three hypotheses relating land cover and land ownership to density and spatial
pattern of buildings, and examined whether building density or spatial pattern of buildings was a better predictor for landscape
fragmentation. Housing locations were mapped from 117 1:24,000-scale USGS topographic maps across northern Wisconsin. Patch-level
landscape metrics were calculated on the terrestrial area remaining after applying 50, 100 and 250 m disturbance zones around
each building. Our results showed that building density and the spatial pattern of buildings were affected mostly by lake
area, public land ownership, and the abundance of coniferous forest, agricultural land, and grassland. A full 40% of the houses
were within 100 m of lakeshores. The clustering of buildings within 100 m of lakeshores limited fragmentation farther away.
In contrast, agricultural and grassland areas were correlated with higher building density, higher fragmentation, and more
dispersed building pattern possible legacies of agricultural settlement patterns. Understanding which factors influence building
density and fragmentation is useful for landscape level planning and ecosystem management in northern Wisconsin and areas
that share similar social and environmental constraints. 相似文献
2.
Watershed analysis of forest fragmentation by clearcuts and roads in a Wyoming forest 总被引:14,自引:0,他引:14
Tinker Daniel B. Resor Catherine A.C. Beauvais Gary P. Kipfmueller Kurt F. Fernandes Charles I. Baker William L. 《Landscape Ecology》1998,13(3):149-165
Remotely sensed data and a Geographic Information System were used to compare the effects of clearcutting and road-building on the landscape pattern of the Bighorn National Forest, in north-central Wyoming. Landscape patterns were quantified for each of 12 watersheds on a series of four maps that differed only in the degree of clearcutting and road density. We analyzed several landscape pattern metrics for the landscape as a whole and for the lodgepole pine and spruce/fir cover classes across these maps, and determined the relative effects of clearcutting and road building on the pattern of each watershed. At both the landscape- and cover class-scales, clearcutting and road building resulted in increased fragmentation as represented by a distinct suite of landscape structural changes. Patch core area and mean patch size decreased, and edge density and patch density increased as a result of clearcuts and roads. Clearcuts and roads simplified patch shapes at the landscape scale, but increased the complexity of lodgepole pine patches. Roads appeared to be a more significant agent of change than clearcuts, and roads which were more evenly distributed across a watershed had a greater effect on landscape pattern than did those which were densely clustered. Examining individual watersheds allows for the comparison of fragmentation among watersheds, as well as across the landscape as a whole. Similar studies of landscape structure in other National Forests and on other public lands may help to identify and prevent further fragmentation of these areas. 相似文献
3.
Studies dealing with community similarity are necessary to understand large scale ecological processes causing biodiversity
loss and to improve landscape and regional planning. Here, we study landscape variables influencing patterns of community
similarity in fragmented and continuous forest landscapes in the Atlantic forest of South America, isolating the effects of
forest loss, fragmentation and patterns of land use. Using a grid design, we surveyed birds in 41 square cells of 100 km2 using the point count method. We used multivariate, regression analyses and lagged predictor autoregressive models to examine
the relative influence of landscape variables on community similarity. Forest cover was the primary variable explaining patterns
of bird community similarity. Similarity showed a sudden decline between 20 and 40% of forest cover. Patterns of land use
had a second order effect; native bird communities were less affected by forest loss in landscapes dominated by tree plantations
(the most suitable habitat for native species) than in landscapes dominated by annual crops or cattle pastures. The effects
of fragmentation were inconclusive. The trade-off between local extinctions and the invasion of extra-regional species using
recently created habitats is probably the mechanism generating the observed patterns of community similarity. Limiting forest
loss to 30–40% of the landscape cover and improving the suitability of human-modified habitats will contribute to maintain
the structure and composition of the native forest bird community in the Atlantic forest. 相似文献
4.
Forest roads and landscape structure in the southern Rocky Mountains 总被引:18,自引:0,他引:18
Roadless areas on public lands may serve as environmental baselines against which human-caused impacts on landscape structure can be measured. We examined landscape structure across a gradient of road densities, from no roads to heavily roaded, and across several spatial scales. Our study area was comprised of 46,000 ha on the Roosevelt National Forest in north-central Colorado. When forest stands were delineated on the basis of seral stage and covertype, no relationship was evident between average stand size and road density. Topography appeared to exert a greater influence on average stand size than did road density. There was a significant positive correlation between the fractal dimension of forest stands and road density across all scales. Early-seral stands existed in greater proportions adjacent to roads, suggesting that the effects of roads on landscape structure are somewhat localized. We also looked at changes in landscape structure when stand boundaries were delineated by roads in addition to covertype and seral stage. Overall, there was a large increase in small stands with simple shapes, concurrent with a decline in the number of stands > 100 ha. We conclude that attempts to quantify the departure from naturalness in roaded areas requires an understanding of the factors controlling the structure of unroaded landscapes, particularly where the influence of topography is great. Because roads in forested landscapes influence a variety of biotic and abiotic processes, we suggest that roads should be considered as an inherent component of landscape structure. Furthermore, plans involving both the routing of new roads and the closure of existing ones should be designed so as to optimize the structure of landscape mosaics, given a set of conservation goals. 相似文献
5.
Estimating the ‘critical’ distance at which adjacent land-use degrades wetland water and sediment quality 总被引:1,自引:0,他引:1
Conversion of forested lands to agriculture or urban/residential areas has been associated with declines in stream and lake water quality. Less attention has been paid to the effects of adjacent land-uses on wetland sediment and water quality and, perhaps more importantly, the spatial scales at which these effects occur. Here we address these issues by examining variation in water and sediment nutrient levels in 73 southeastern Ontario, Canada, wetlands. We modeled the relationship between water and sediment nutrient concentrations and various measures of adjacent land-use such as forest cover and road density, measured over increasing distances from the wetland edge. We found that water nitrogen and phosphorous levels were negatively correlated with forest cover at 2250 meters from the wetland edge, while sediment phosphorous levels were negatively correlated with wetland size and forest cover at 4000 meters and positively correlated with the proportion of land within 4000 meters that is itself wetland. These results suggest that the effects of adjacent land-use on wetland sediment and water quality can extend over comparatively large distances. As such, effective wetland conservation will not be achieved merely through the creation of narrow buffer zones between wetlands and more intensive land-uses. Rather, sustaining high wetland water quality will require maintaining a heterogeneous regional landscape containing relatively large areas of natural forest and wetlands. 相似文献
6.
Jenica M. Allen Thomas J. Leininger James D. Hurd Jr. Daniel L. Civco Alan E. Gelfand John A. Silander Jr. 《Landscape Ecology》2013,28(9):1671-1686
Woody invasive plants are an increasing component of the New England flora. Their success and geographic spread are mediated in part by landscape characteristics. We tested whether woody invasive plant richness was higher in landscapes with many forest edges relative to other forest types and explained land use/land cover and forest fragmentation patterns using socioeconomic and physical variables. Our models demonstrated that woody invasive plant richness was higher in landscapes with more edge forest relative to patch, perforated, and especially core forest types. Using spatially-explicit, hierarchical Bayesian, compositional data models we showed that infrastructure and physical factors, including road length and elevation range, and time-lagged socioeconomic factors, primarily population, help to explain development and forest fragmentation patterns. Our social–ecological approach identified landscape patterns driven by human development and linked them to increased woody plant invasions. Identifying these landscape patterns will aid ongoing efforts to use current distribution patterns to better predict where invasive species may occur in unsampled regions under current and future conditions. 相似文献
7.
Impacts of road corridors on urban landscape pattern: a gradient analysis with changing grain size in Shanghai, China 总被引:4,自引:0,他引:4
Urbanization is one of the most important driving forces for land use and land cover change. Quantifying urban landscape pattern
and its change is fundamental for monitoring and assessing ecological and socioeconomic consequences of urbanization. As the
largest city in the country, Shanghai is now the fastest growing city in China. Using land use data set of 2002 and combining
gradient analysis with landscape metrics, we analyzed landscape pattern of Shanghai with increasing grain size to study the
impacts of road corridors on urban landscape pattern. Landscape metrics were computed along a 51×9 km2 transect cutting across Shanghai with a moving window. The results showed that the urban landscape pattern of Shanghai was
greatly changed when road corridors were merged with urban patches and the variation of patch density would alter when grain
size changed. As a linear land use type, road corridors exhibited a different spatial signature comparing with other land
use types and distinctive behavior with increasing grain size. Merging road and urban patches resulted in a sharp reduction
in patch density, mainly caused by segmentation of roads corridors. The results suggested that grain size around 7.5 m might
be optimal for urban landscape analysis. Landscape patch density is significantly correlated with road percent coverage and
the most important effect of road corridors in urban landscape is increased habitat fragmentation. 相似文献
8.
Lisa Freudenberger Peter R. Hobson Slaven Rupic Guy Pe’er Martin Schluck Julia Sauermann Stefan Kreft Nuria Selva Pierre L. Ibisch 《Landscape Ecology》2013,28(7):1353-1369
The expansion of roads, and the subsequent changes to the surrounding landscape not only lead to landscape fragmentation but also have been shown to be a key driver of biodiversity loss and ecosystem degradation. Local declines of species abundance as well as changes in animal behaviour have drawn attention to wider ecosystem effects including altered species composition and a degradation of ecosystem functioning. However, methods for measuring and quantifying the distribution and environmental impacts of roads are not yet fully developed. We present a new technique for assessing the potential impacts of roads on biodiversity using a spatial road disturbance index (SPROADI). The index is calculated from three sub-indices: traffic intensity as a measure of traffic volume per time and space; vicinity impact, which is the assessment of edge effect of roads on adjacent habitats (the road-effect zone); and fragmentation grade, which provides an indication of the degree to which the landscape is intersected by roads. SPROADI was then tested using data from the Federal State of Brandenburg in north-eastern Germany. A sensitivity analysis was carried out on the results to assess the robustness of the index. The findings revealed expected patterns of high road disturbance in urban and peri-urban landscapes surrounding Berlin. Less obvious were the high levels of road density and impacts in forest plantations across the southern region of Brandenburg, and low levels of road disturbance in agricultural crop lands of the north-western region. Results were variable for areas under some form of protection. The only national park displayed substantially lower SPROADI values in contrast to the surrounding non-protected areas whilst other protected area categories, which were landscape conservation areas and nature parks, revealed SPROADI values that were equally high as those for non-protected areas. The results of this study demonstrate the strengths and potential applications of SPROADI as a quantitative means for identifying low-traffic areas in the context of conservation and sustainable transport planning. 相似文献
9.
Accessibility as a determinant of landscape transformation in western Honduras: linking pattern and process 总被引:11,自引:2,他引:11
This study evaluates the relationship between landscape accessibility and land cover change in Western Honduras, and demonstrates
how these relationships are influenced by social and economic processes of land use change in the region. The study area presents
a complex mosaic of land cover change processes that involve approximately equal amounts of reforestation and deforestation.
Landsat Thematic Mapper (TM) satellite imagery of 1987, 1991 and 1996 was used to create three single date classifications
and a land cover change image depicting the sequence of changes in land cover between 1987–1991–1996. An accessibility analysis
examined land cover change and landscape fragmentation relative to elevation and distance from roads. Between 1987 and 1991,
results follow ‘expected’ trends, with more accessible areas experiencing greater deforestation and fragmentation. Between
1991 and 1996 this trend reverses. Increased deforestation is found in areas distant from roads, and at higher elevations;
a result of government policies promoting expansion of mountain coffee production for export. A ban on logging, and abandonment
of marginally productive agricultural fields due to agricultural intensification in other parts of the landscape, has led
to increased regrowth in accessible regions of the landscape. Roads and elevation also present different obstacles in terms
of their accessibility, with the smallest patches of cyclical clearing and regrowth, relating mostly to the agricultural fallow
cycle, found at the highest elevations but located close to roads. This research highlights the need to locate analyses of
land cover change within the context of local socio-economic policies and land use processes.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Context
Understanding connectivity patterns in relation to habitat fragmentation is essential to landscape management. However, connectivity is often judged from expert opinion or species occurrence patterns, with very few studies considering the actual movements of individuals. Path selection functions provide a promising tool to infer functional connectivity from animal movement data, but its practical application remains scanty.Objectives
We aimed to describe functional connectivity patterns in a forest carnivore using path-level analysis, and to explore how connectivity is affected by land cover patterns and road networks.Methods
We radiotracked 22 common genets in a mixed forest-agricultural landscape of southern Portugal. We developed path selection functions discriminating between observed and random paths in relation to landscape variables. These functions were used together with land cover information to map conductance surfaces.Results
Genets moved preferentially within forest patches and close to riparian habitats. Functional connectivity declined with increasing road density, but increased with the proximity of culverts, viaducts and bridges. Functional connectivity was favoured by large forest patches, and by the presence of riparian areas providing corridors within open agricultural land. Roads reduced connectivity by dissecting forest patches, but had less effect on riparian corridors due to the presence of crossing structures.Conclusions
Genet movements were jointly affected by the spatial distribution of suitable habitats, and the presence of a road network dissecting such habitats and creating obstacles in areas otherwise permeable to animal movement. Overall, the study showed the value of path-level analysis to assess functional connectivity patterns in human-modified landscapes.11.
We explored the usefulness of three satellite land cover data sets available to land managers in south-central Sweden for
conservation planning using four deciduous forest focal resident bird species with different habitat requirements. Habitat
suitability models using empirical species-specific habitat parameters and a Geographic Information System were applied to
evaluate and compare the degree of consistency among three different land cover data sets. The study area encompassed 10,000 km2 in a landscape mosaic of managed boreal forests and is within the distribution range of all four focal species. Although
the three land cover data sets indicated similar total amounts of deciduous forest, the habitat suitability models showed
that different land cover data yielded inconsistent results regarding the amount and distribution of suitable habitat within
5×5 km grid cells. Given this sensitivity to the choice of land cover data sets, the habitat suitability models showed positive
relationships among the selected focal species for each land cover data set separately. As expected, decreasing amounts of
suitable habitat were identified for species with higher specialisation. Thus, because habitat suitability models are an appropriate
way to gain insight into the functionality and connectivity of habitat networks, land cover data must be carefully evaluated
and if necessary combined with other landscape information for effective conservation planning. 相似文献
12.
Forest fragmentation in Loudoun County,Virginia, USA evaluated with multitemporal Landsat imagery 总被引:1,自引:0,他引:1
In order to study forest fragmentation in the Virginia, USA Piedmont, a series of Landsat images from 1973, 1987, and 1999 covering a rapidly developing area (Loudoun County) was used to classify forest from non-forest. The classified images were analyzed using a geographic information system (GIS) to determine the spatial and temporal patterns of fragmentation, and to relate these patterns to infrared radiance provided by Landsat Enhanced Thematic Mapper Plus (ETM+) band 6. The analysis was concentrated on eleven major watersheds of Loudoun County. The relationship between urbanized area per watershed and mean fragment size showed a strong negative decay form (r
2=0.757, p<0.0001). Analysis of four landscape metrics showed increasing fragmentation of forest cover, particularly from 1987 to 1999, as well as an increase in forest edge and shape complexity. Of the landscape metrics used, the perimeter-to-area (P/A) ratio showed the strongest relationship with mean radiance of forest patches. In addition, there was a negative, linear relationship between distance from major roads and band 6 radiance of forested pixels. Overall, the study shows that landscape metrics can convey meaningful information on biophysical changes associated with forest fragmentation at broad scales. These changes suggest that ambient temperature increases associated with urban sprawl may have important, long-term implications for ecophysiological processes. 相似文献
13.
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
14.
Context
Habitat loss and habitat fragmentation negatively affect amphibian populations. Roads impact amphibian species through barrier effects and traffic mortality. The landscape variable ‘accessible habitat’ considers the combined effects of habitat loss and roads on populations.Objectives
The aim was to test whether accessible habitat was a better predictor of amphibian species richness than separate measures of road effects and habitat loss. I assessed how accessible habitat and local habitat variables determine species richness and community composition.Methods
Frog and tadpole surveys were conducted at 52 wetlands in a peri-urban area of eastern Australia. Accessible habitat was delineated using a highway. Regressions were used to examine relationships between species richness and eleven landscape and local habitat variables. Redundancy analysis was used to examine relationships between community composition and accessible habitat and local habitat variables.Results
Best-ranked models of species richness included both landscape and local habitat variables. There were positive relationships between species richness and accessible habitat and distance to the highway, and uncertain relationships with proportion cover of native vegetation and road density. There were negative relationships between species richness and concreted wetlands and wetland electrical conductivity. Four species were positively associated with accessible habitat, whereas all species were negatively associated with wetland type.Conclusions
Barrier effects caused by the highway and habitat loss have negatively affected the amphibian community. Local habitat variables had strong relationships with species richness and community composition, highlighting the importance of both availability and quality of habitat for amphibian conservation near major roads.15.
Forest fragmentation and regrowth in an institutional mosaic of community, government and private ownership in Nepal 总被引:1,自引:0,他引:1
Harini Nagendra Sajid Pareeth Bhawna Sharma Charles M. Schweik Keshav R. Adhikari 《Landscape Ecology》2008,23(1):41-54
This study analyzes forest change in an area of Nepal that signifies a delicate balance between sustaining the needs and livelihood
of a sizable human population dependent on forest products, and an effort to protect important wildlife and other natural
resources. The study area, a portion of the Chitwan valley district of Nepal, represents what may be becoming a common institutional
mosaic in many countries of the world who have a population reliant on forest products for their livelihood: (1) a national
park; (2) a designated park buffer involving participatory forest management programs; (3) scattered patches of designated
community forest; and (4) large areas of adjacent landscape made up of mostly private landholdings under agricultural practices.
Utilizing Landsat images from 1989 and 2000, we analyze land cover change in each of these management zones using landscape
ecology metrics and quantifying proportional distributions of land cover categories. Our results show significant differences
in terms of land cover dynamics and landscape spatial pattern between these land ownership classes. These findings indicate
that community-based institutions (participatory management programs in the park buffer and the designated community forests)
are capable of halting or even reversing trends in deforestation and forest fragmentation. 相似文献
16.
Hanem G. Abouelezz Therese M. Donovan Ruth M. Mickey James D. Murdoch Mark Freeman Kimberly Royar 《Landscape Ecology》2018,33(8):1301-1318
Context
The analysis of individual movement choices can be used to better understand population-level resource selection and inform management.Objectives
We investigated movements and habitat selection of 13 bobcats in Vermont, USA, under the assumption individuals makes choices based upon their current location. Results were used to identify “movement-defined” corridors.Methods
We used GPS-collars and GIS to estimate bobcat movement paths, and extracted statistics on land cover proportions, topography, fine-scale vegetation, roads, and streams within “used” and “available” space surrounding each movement path. Compositional analyses were used to determine habitat preferences with respect to landcover and topography; ratio tests were used to determine if used versus available ratios for vegetation, roads, and streams differed from 1. Results were used to create travel cost maps, a primary input for corridor analysis.Results
Forested and scrub-rock land cover were most preferred for movement, while developed land cover was least preferred. Preference depended on the composition of the “available” landscape: Bobcats moved?>?3 times more quickly through forest and scrub-rock habitat when these habitats were surrounded by agriculture or development than when the available buffer was similarly composed. Overall, forest edge, wetland edge and higher stream densities were selected, while deep forest core and high road densities were not selected. Landscape-scale connectivity maps differed depending on whether habitat suitability, preference, or selection informed the travel cost map.Conclusions
Both local and landscape scale land cover characteristics affect habitat preferences and travel speed of bobcats, which in turn can inform management and conservation activities.17.
We analyzed forest clearing and regrowth over a 23-year time period for 21 forest concession and management units within the
Maya Biosphere Reserve(MBR), Guatemala. The study area as a whole experienced a clearing rate of0.16%/year from 1974 through
1997. The overall clearing rate appears rather low when averaged over the entire study area over 23 years because most of
the reserve was inaccessible. However, despite the granting of legal protection to the MBR in 1990, clearing rates continued
to rise, with the highest rates occurring in the most recent time period in the analysis, 1995 to1997. Higher rates of clearing
relative to regrowth occurred in newly established communities and in the Reserve's buffer zone, where the clearing of high
forest was preferred for pasture development. Exploratory models were built and analyzed to examine the effects of various
landscape variables on forest clearing. The different units in the analysis showed different relationships of forest clearing
with variables such as forest cover type and distance to access(roads and river corridors). Where available, socio-economic
household survey data helped to explain patterns and trends observed in the time series Landsat imagery. A strong relationship
between forest clearing and distance to access was demonstrated. More clearing occurred further from roads during later time
periods as farmers moved deeper into the forest to find land to clear. Communities inside the MBR that were less dependent
on farming had forest clearing to regrowth ratios of one:one or less. These communities used fallow fields in greater proportions
than communities in the Reserve's buffer zone. General trends in clearing by forest cover type suggest a preference for clearing
high forest (bosque alto) types found on the higher elevation, better-drained soils, and fallow fields,and an avoidance of low-lying, seasonally flooded
terrain(bajos). Satellite remote sensing observations of forest clearing and regrowth patterns can provide an objective source of information
to complement socio-economic studies of the human driving forces in land cover and land use change.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
Steven Walters 《Landscape Ecology》2007,22(6):867-881
Understanding the impacts of habitat fragmentation on dispersal is an important issue in landscape and conservation ecology.
Here I examine the effects of fine- to broad-scale patterns in landscape structure on dispersal success of organisms with
differing life-history traits. An individual-based model was used to simulate dispersal of amphibian-like species whose movements
were driven by land cover and moisture conditions. To systematically control spatial pattern, a landscape model was created
by merging simulated land cover maps with synthetic topographic surfaces. Landscapes varied in topographic roughness and spatial
contagion in agriculture and urban land cover. Simulations included three different species types that varied in their maximum
potential dispersal distances by 1-, 2-, or 4-fold. Two sets of simulations addressed effects of varying aspects of landscape
structure on dispersal success. In the first set of simulations, which incorporated variable distances between breeding patches,
dispersal success was lowest for all species types when anthropogenic cover was patchily distributed. In the second set, with
interpatch distances held constant as landscape composition varied, dispersal success decreased as anthropogenic cover became
spatially contagious. Both sets revealed strong main effects of species characteristics, interpatch distances and landscape
composition on dispersal success; furthermore, scale-dependent patterns in land cover and moisture gradients had a stronger
effect on longer- than shorter-ranging species types. Taken together, these simulations suggest that heuristic conservation
strategies could potentially be developed based on important but limited life history information. 相似文献
19.
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
20.
Holly E. Mutascio Shannon E. Pittman Patrick A. Zollner Laura E. D’Acunto 《Landscape Ecology》2018,33(2):257-274