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1.
The BOSAWAS Natural Resource Reserve of Nicaragua was established in 1991, to protect a portion of the remaining tropical rain forest and to promote the sustainable use of the region's resources. Information required to effectively manage the reserve includes the extents and locations of present land-cover types and recent land-cover changes in the management use zones that were delineated by local indigenous communities. These zones include areas designated for conservation, limited resource extraction, agriculture, and watershed protection. Land-cover for 1986 and 1995 was identified for three of the communities from remotely sensed images and then input into a geographic information system database to identify land-cover types within these management use zones. For both dates of the analysis, advanced forest was the dominant land cover, with the conservation zones entirely forested. The amount of both agricultural land and scrub/early secondary forest increased between the two dates, with much of these land-cover classes occurring in the agriculture zones. Conflicts between the land-cover present and designated use were identified in some of the limited-use buffer and watershed protection zones. Changes between 1986 and 1995 were identified by overlaying the two land-cover data sets. Three change processes were identified as occurring: deforestation, reforestation, and reconversion. Changes were concentrated in the agriculture zones but were found to occur in every type of zone, except for conservation. The results of this study will establish baseline information for the future management of the BOSAWAS Reserve, an important component in uniting conservation areas along the Central American isthmus.  相似文献   

2.
Forest cover in the upper Wabash River basin in Indiana was fragmented due to agricultural conversion beginning more than 175 years ago. Currently, urban expansion is an important driver of land-use change in the basin. A land transformation model was applied to the basin to forecast land use from 2000 to 2020. We assessed the effect of this projected land-use change scenario on five forest rodent species at three scales: using occupancy models at the patch level, proportional occupancy models at the landscape level, and ecologically scaled landscape indices to assess the change in connectivity at the watershed level. At the patch and landscape scales, occupancy models had low predictability but suggest that gray squirrels are most susceptible to land-use change. At the watershed scale, declines in connectivity did not correspond with the decline of forest. This study highlights the importance of map resolution and consideration of matrix elements in constructing forecast models. Unforeseen drivers of land use, such as changing economic incentives, may also have important ramifications.  相似文献   

3.
The Barataria Basin, Louisiana, USA, is an extensive wetland and coastal estuary system of great economic and intrinsic value. Although high rates of wetland loss along the coastal margin of the Barataria Basin have been well documented, little information exists on whether freshwater wetlands in the upper basin have changed. Our objectives were to quantify land-cover change in the upper basin over 20 years from 1972–1992 and to determine land-cover transition rates among land-cover types. Using 80-m resolution Landsat MSS data from the North American Landscape Characterization (NALC) data archive, we classified images from three time steps (1972, 1985, 1992) into six land-cover types: agriculture, urban, bottomland hardwood forest, swamp forest, freshwater marsh, and open water. Significant changes in land cover occurred within the upper Barataria Basin over the study period. Urban land increased from 8% to 17% of the total upper basin area, primarily due to conversions from agricultural land, and to a lesser degree, bottomland forest. Swamp forest increased from 30% to 41%, associated with conversions from bottomland hardwood forest and freshwater marsh. Overall, bottomland forest decreased 38% and total wetland area increased 21%. Within the upper Barataria, increases in total wetland area may be due to land subsidence. Based on our results, if present trends in the reduction of bottomland forest land cover were to continue, the upper Barataria Basin may have no bottomland hardwood forests left by the year 2025, as it is subjected to multiple stressors both in the higher elevations (from urbanization) and lower elevations (most likely from land subsidence). These results suggest that changes in the upper freshwater portions of coastal estuaries can be large and quite different from patterns observed in the more saline coastal margins.  相似文献   

4.
Biosphere Reserves attempt to align existing biodiversity conservation with sustainable resource use, specifically for improving socio-economic circumstances of resident communities. Typically, the Biosphere Reserve model is applied to an established landscape mosaic of existing land uses; these are often socio-ecological systems where strict environmental protection and community livelihoods are in conflict, and environmental degradation frequently accompanies “use”. This raises challenges for successful implementation of the model, as the reality of the existing land-use mosaic undermines the theoretical aspirations of the Biosphere concept. This study focuses on the Kruger to Canyons Biosphere Reserve (K2C), South Africa; a socio-ecological landscape where formal conservation is juxtaposed against extensive impoverished rural communities. We focus on land-cover changes of the existing land-use mosaic (1993–2006), specifically selected land-cover classes identified as important for biodiversity conservation and local-level resource utilization. We discuss the implications of transformation for conservation, sustainable resource-use, and K2C’s functioning as a “Biosphere Reserve”. Spatially, changes radiated outward from the settlement expanse, with little regard for the theoretical land-use zonation of the Biosphere Reserve. Settlement growth tracked transport routes, transforming cohesive areas of communal-use rangelands. Given the interdependencies between the settlement population and local environmental resources, the Impacted Vegetation class expanded accordingly, fragmenting the Intact Vegetation class, and merging rangelands. This has serious implications for sustainability of communal harvesting areas, and further transformation of intact habitat. The distribution and magnitude of Intact Vegetation losses raise concerns around connectivity and edge effects, with long-term consequences for ecological integrity of remnant habitat, and K2C’s existing network of protected areas.  相似文献   

5.
We compared the composition of diatom assemblages collected from New Jersey Pinelands blackwater streams draining four different land uses, including forest land, abandoned-cranberry bogs, active-cranberry bogs, and developed and upland-agricultural land. Over a 2-year period (2002-2003), we collected 132 diatom taxa at 14 stream sites. Between-year variability in the composition of stream samples was high. Most diatom species were rarely encountered and were found in low abundance. Specific conductance and pH were higher at developed/agricultural sites compared with all other site types. Neither species richness nor genus richness was significantly different between stream types. However, clear community patterns were evident, and a significant difference in species composition existed between the developed/agricultural sites and both cranberry and forest sites. The primary community gradient, represented by the first axis of a DCA ordination, was associated with variations in pH and specific conductance. Although community patterns revealed by ordinating the data collected in 2002 differed from those obtained using the 2003 data, both ordinations contrasted the developed/agricultural sites and the other sites. Acidobiontic and acidophilous diatoms characterized the dominant species at forest, abandoned-bog, and cranberry sites, whereas indifferent species dominated the developed/agricultural samples. Although our study demonstrated a relationship between the composition of diatom assemblages and watershed conditions, several factors, including taxonomic problems, the large number of diatom species, incomplete pH classifications, and year-to-year variability may limit the utility of diatom species as indicators of watershed conditions in the New Jersey Pinelands.  相似文献   

6.
Changes in forested landscapes may have important consequences for ecosystem services and biodiversity conservation. In northern Spain, major changes in land use occurred during the second half of the 20th century, but their impacts on forests have not been quantified. We evaluated the dynamics of landscape and forest distribution patterns between 1957 and 2003 in Fragas do Eume Natural Park (northwestern Spain). We used orthoimages and a set of standard landscape metrics to determine transitions between land cover classes and to examine forest distribution patterns. Eucalypt plantations showed the greatest increase in area (197%) over time. Furthermore, transitions to eucalypt plantations were found in all major land cover classes. Forest showed a net decline of 20% in total area and represented 30% of the landscape area in 2003. Forest losses were mainly due to eucalypt plantations and the building of a water reservoir, while forest gains were due to increases in shrubland, meadows and cultivated fields which had been recolonised. Forest patch size and core area decreased, and edge length increased over time. In turn, increases were obtained in mean distance between forest patches, and in adjacency to eucalypt plantations and to a water reservoir. These results suggest an increase in forest fragmentation from 1957 to 2003, as well as a change in the nature of the habitat surrounding forest patches. This study shows that land use changes, mostly from eucalypt plantation intensification, negatively affected forested habitats, although some regeneration was ongoing through ecological succession from land abandonment.  相似文献   

7.
To facilitate forest planning and management on National Wildlife Refuges, we synthesized multiple data sources to describe land ownership patterns, land cover, landscape pattern, and changes in forest composition for four ecoregions and their associated refuges of the Upper Midwest. We related observed patterns to ecological processes important for forest conservation and restoration, with specific attention to refuge patterns of importance for forest landbirds of conservation priority. The large amount of public land within the ecoregions (31–80%) suggests that opportunities exist for coarse and meso-scale approaches to conserving and restoring ecological processes affecting the refuges, particularly historical fire regimes. Forests dominate both ecoregions and refuges, but refuge forest patches are generally larger and more aggregated than in associated ecoregions. Broadleaf taxa have increased in dominance in the ecoregions and displaced fire-dependent taxa such as pine (Pinus spp.) and other coniferous species; these changes in forest composition have likely also affected refuge forests. Despite compositional changes, larger forest patches on refuges suggests that they may provide better habitat for area-sensitive forest landbirds of mature, compositionally diverse forests than surrounding lands if management continues to promote increased patch size. We reason that although fine-scale research and monitoring for species of conservation priority is important, broad scale (ecoregional) assessments provide crucial context for effective forest and wildlife management in protected areas.  相似文献   

8.
Land-Cover Change Trajectories in Northern Ghana   总被引:3,自引:0,他引:3  
Land-cover change trajectories are an emergent property of complex human–environment systems such as the land-use system. An understanding of the factors responsible for land change trajectories is fundamental for land-use planning and the development of land-related policies. The aims of this study were to characterize and identify the spatial determinants of agricultural land-cover change trajectories in northern Ghana. Land-cover change trajectories were defined using land-cover maps prepared from Landsat Thematic Mapper dataset acquired in 1984, 1992, and 1999. Binary logistic regression was used to model the probability of observing the trajectories as a function of spatially explicit biophysical and socioeconomic independent variables. Population densities generally increased along the continuum of land-use intensity, whereas distance from market and roads generally decreased along this continuum. Apparently, roads and market serve as incentives for settlement and agricultural land use. An increase in population density is an important spatial determinant only for trajectories where the dominant change process is agricultural extensification. A major response to population growth is an increase in cultivation frequency around the main market. Agricultural intensification is highly sensitive to accessibility by roads. The increase in land-use intensity is also associated with low soil quality. These results suggest the need for policies to restore soil fertility for agricultural sustainability. The models also provide a means for identifying functional relationships for in-depth analyses of land-use change in Ghana.  相似文献   

9.
Site-specific estimates of the values of spatial configuration and forest composition are presented. Amenity values of forest patches are found to vary the most by urban and sprawling development patterns of specific areas and forest types. For example, smaller patches of deciduous forest are more highly valued in the urban and sprawling areas of Greensboro, North Carolina, whereas larger patches of deciduous forest are more highly valued in the urban and sprawling areas of Greenville, South Carolina. Within the Greenville and Greensboro areas, visible landscape complexity is highly valued for deciduous and evergreen forest patches, whereas lower visible landscape complexity, i.e., smoothly trimmed forest patch boundaries, is highly valued for mixed forest patches.  相似文献   

10.
Urbanization is one of the most important aspects of global change. The process of urbanization has a significant impact on the terrestrial ecosystem carbon cycle. The Yangtze Delta region has one of the highest rates of urbanization in China. In this study, carried out in Jiangyin County as a representative region within the Yangtze Delta, land use and land cover changes were estimated using Landsat TM and ETM+ imagery. With these satellite data and the BEPS process model (Boreal Ecosystem Productivity Simulator), the impacts of urbanization on regional net primary productivity (NPP) and annual net primary production were assessed for 1991 and 2002. Landsat-based land cover maps in 1991 and 2002 showed that urban development encroached large areas of cropland and forest. Expansion of residential areas and reduction of vegetated areas were the major forms of land transformation in Jiangyin County during this period. Mean NPP of the total area decreased from 818 to 699 gCm(-2)yr(-1) during the period of 1991 to 2002. NPP of cropland was only reduced by 2.7% while forest NPP was reduced by 9.3%. Regional annual primary production decreased from 808 GgC in 1991 to 691 GgC in 2002, a reduction of 14.5%. Land cover changes reduced regional NPP directly, and the increasing intensity and frequency of human-induced disturbance in the urbanized areas could be the main reason for the decrease in forest NPP.  相似文献   

11.
We used remote sensing and GIS in conjunction with multivariate statistical methods to: (i) quantify landscape composition (land cover types) and configuration (patch density, diversity, fractal dimension, contagion) for five coastal watersheds of Kalloni gulf, Lesvos Island, Greece, in 1945, 1960, 1971, 1990 and 2002/2003, (ii) evaluate the relative importance of physical (slope, geologic substrate, stream order) and human (road network, population density) variables on landscape composition and configuration, and (iii) characterize processes that led to land cover changes through land cover transitions between these five successive periods in time. Distributions of land cover types did not differ among the five time periods at the five watersheds studied because the largest cumulative changes between 1945 and 2002/2003 did not take place at dominant land cover types. Landscape composition related primarily to the physical attributes of the landscape. Nevertheless, increase in population density and the road network were found to increase heterogeneity of the landscape mosaic (patchiness), complexity of patch shape (fractal dimension), and patch disaggregation (contagion). Increase in road network was also found to increase landscape diversity due to the creation of new patches. The main processes involved in land cover changes were plough-land abandonment and ecological succession. Landscape dynamics during the last 50 years corroborate the ecotouristic-agrotouristic model for regional development to reverse trends in agricultural land abandonment and human population decline and when combined with hypothetical regulatory approaches could predict how this landscape could develop in the future, thus, providing a valuable tool to regional planning.  相似文献   

12.
This paper presents an approach to modeling land-cover change as a function of land-use change. We argue that, in order to model the link between socio-economic change and changes in forest cover in a region that is experiencing residential and recreational development and agricultural abandonment, land-use and land-cover change need to be represented as separate processes. Forest-cover change is represented here using two transition probabilities that were calculated from Landsat imagery and that, taken together, describe a Markov transition matrix between forest and non-forest over a 10-year period. Using a three-date land-use data set, compiled and interpreted from digitized parcel boundaries, and scanned aerial photography for 136 sites (c. 2500 ha) sampled from the Upper Midwest, USA, we test functional relationships between forest-cover transition probabilities, standardized to represent changes over a decade, and land-use conditions and changes within sample sites. Regression models indicated that about 60% of the variation in the average forest-cover transition probabilities (i.e. from forest to non-forest and vice versa) can be predicted using three variables: amount of agricultural land use in a site; amount of developed land use; and the amount of area increasing in development. In further analysis, time lags were evaluated, showing that agricultural abandonment had a relatively strong time-lag effect but development did not. We demonstrate an approach to using forest-cover transition probabilities to develop spatially-constrained simulations of forest-cover change. Because the simulations are based on transition probabilities that are indexed to a particular time and place, the simulations are improved over previous applications of Markov transition models. This modeling approach can be used to predict forest-cover changes as a result of socio-economic change, by linking to models that predict land-use change on the basis of exogenous human-induced drivers.  相似文献   

13.
The impacts of land use and land cover (LULC) change in buffer zones surrounding protected ecological reserves have important implications for the management and conservation of these protected areas. This study examines the spatial and temporal patterns of LULC change along the boundary of Rio Abiseo National Park in the Northern Peruvian Andes. Landscape change within four ecological zones was evaluated based on trends expected to occur between 1987 and 2001. Landsat TM and ETM imagery were used to produce LULC classification maps for both years using a hybrid supervised/unsupervised approach. LULC changes were measured using landscape metrics and from-to change maps created by post-classification change detection. Contrary to expectations, tropical upper wet montane forest increased despite being threatened by human-induced fires and cattle grazing of the highland grasslands inside the park. Within the park’s buffer zone, tropical moist forest remnants were fragmented into more numerous and smaller patches between 1987 and 2001; this was in part due to conversion into agricultural land. The methods used in this study provide an effective way to monitor LULC change detection and support the management of protected areas and their surrounding environments.  相似文献   

14.
运用景观生态学原理,借助GIS技术,选取景观指数对豫西黄河流域土地利用景观格局进行分析。结果表明,林地和以旱地为主的农业景观是豫西黄河流域的主体景观类型;各景观类型间斑块密度值差距较大,斑块形状指数差异较明显,总体上较简单;研究区域景观异质性和多样性较高,各景观类型所占比例差异较大,农田和林地占有较大优势。该区域景观破碎化程度较小,特别是西部地区地形起伏较大,人类干扰活动相对较小。  相似文献   

15.
Reindeer husbandry and forestry are two main land users in boreal forests in northern Sweden. Modern forestry has numerous negative effects on the ground-growing and arboreal lichens that are crucial winter resources for reindeer husbandry. Using digitized historical maps, we examined changes in the forest landscape structure during the past 100 years, and estimated corresponding changes in suitability of forest landscape mosaics for the reindeer winter grazing. Cover of old coniferous forests, a key habitat type of reindeer herding system, showed a strong decrease during the study period, whereas clear-cutting and young forests increased rapidly in the latter half of the 20th century. The dominance of young forests and fragmentation of old-growth forests (decreased patch sizes and increased isolation) reflect decreased amount of arboreal lichens as well as a lowered ability of the landscape to sustain long-term persistence of lichens. The results further showed that variation in ground lichen cover among sites was mainly related to soil moisture conditions, recent disturbances, such as soil scarification and prescribed burning, and possibly also to forest history. In general, the results suggest that the composition and configuration of the forest landscape mosaic has become less suitable for sustainable reindeer husbandry.  相似文献   

16.
The Pinelands National Reserve was created in 1978 when private interests and federal, state, and local governments allied to protect 378,000 ha (935,000 acres) of New Jersey's Pine Barrens from encroaching development. An intergovernmental authority, the Pinelands Commission, manages the reserve by implementing a regional plan to guide development away from environmentally sensitive areas and into designated growth centers. Through transferable development rights, financial gains from development in growth centers are used to compensate owners and localities in the reserve who might otherwise have developed their lands. The national reserve strategy contrasts with other federal strategies for preserving unique environments in which the federal government exercises exclusive control (e.g., national parks, monuments, and recreation areas). This article describes the strategy applied in the Pinelands and discusses the conditions in which it may be more or less effective than other strategies used to protect unique or valued landscapes. It then compares the Pinelands model with the strategies and conditions of california's Redwood National Park and Point Reyes National Seashore to develop propositions about the circumstances in which one or another strategy is more likely to be viable. Finally, it applies these propositions to the possibilities for future forest preservation in New England.  相似文献   

17.
Water quality in streams is dependent on landscape metrics at catchment and wetland scales. A study was undertaken to evaluate the correlation between landscape metrics, namely patch density and area, shape, heterogeneity, aggregation, connectivity, land-use ratio, and water quality variables (salinity, nutrients, sediments, alkalinity, other potential pollutants and pH) in the agricultural areas of a semiarid Mediterranean region dominated by irrigated farmlands (NE Spain). The study also aims to develop wetland construction criteria in agricultural catchments. The percentage of arable land and landscape homogeneity (low value of Simpson index) are significantly correlated with salinity (r(2) = 0.72) and NO(3)-N variables (r(2) = 0.49) at catchment scale. The number of stock farms was correlated (Spearman's corr. = 0.60; p < 0.01) with TP concentration in stream water. The relative abundance of wetlands and the aggregation of its patches influence salinity variables at wetland scale (r(2) = 0.59 for Na(+) and K(+) concentrations). The number and aggregation of wetland patches are closely correlated to the landscape complexity of catchments, measured as patch density (r(2) = 0.69), patch size (r(2) = 0.53), and landscape heterogeneity (r(2) = 0.62). These results suggest that more effective results in water quality improvement would be achieved if we acted at both catchment and wetland scales, especially reducing landscape homogeneity and creating numerous wetlands scattered throughout the catchment. A set of guidelines for planners and decision makers is provided for future agricultural developments or to improve existing ones.  相似文献   

18.
In the Portland, Oregon, metropolitan region, an urban growth boundary (UGB) was established in 1979 to protect farm and forest lands from urban encroachment. Most of the literature on the impact of Oregon's land-use legislation has been on the urban side of the issue--primarily the relative success Portland has had in containing urban sprawl. The landscape component of this rural transformation is typically considered only as a passive backdrop to urban expansion. Portland provides an excellent site to examine the relationship city-dwellers have to nearby agricultural areas. Rapid urban growth in the 1990s pushed suburban development to the edge of the UGB creating stark contrasts between urban and rural land uses in parts of the metropolitan area. This study examines the impact of the UGB on rural landscape change in Portland. We combine findings from land-use analysis and surveys of urban and rural residents to suggest ways to merge the amenity values of landscape with planning policy regarding the UGB.  相似文献   

19.

In the Portland, Oregon, metropolitan region, an urban growth boundary (UGB) was established in 1979 to protect farm and forest lands from urban encroachment. Most of the literature on the impact of Oregon's land-use legislation has been on the urban side of the issue—primarily the relative success Portland has had in containing urban sprawl. The landscape component of this rural transformation is typically considered only as a passive backdrop to urban expansion. Portland provides an excellent site to examine the relationship city-dwellers have to nearby agricultural areas. Rapid urban growth in the 1990s pushed suburban development to the edge of the UGB creating stark contrasts between urban and rural land uses in parts of the metropolitan area. This study examines the impact of the UGB on rural landscape change in Portland. We combine findings from land-use analysis and surveys of urban and rural residents to suggest ways to merge the amenity values of landscape with planning policy regarding the UGB.  相似文献   

20.
Nutrient loading into rivers is generally increased by human-induced land-use changes and can lead to increased surface water pollution. Understanding the extent to which land-use patterns influence nutrient loading is critical to the development of best-management practices aimed at water-quality improvement. In this study, we investigated total nitrogen (total N) concentration as a function of land-use patterns and compared the relative significance of the identified land-use variables for 26 upstream watersheds of the Haihe River basin. Seven land-use intensity and nine landscape complexity variables were selected to form the land-use pattern metrics on the landscape scale. After analyzing the significance of the land-use pattern metrics, we obtained five dominant principal components: human-induced land-use intensity, landscape patch-area complexity, area-weighted landscape patch-shape complexity, forest and grassland area, and landscape patch-shape complexity. A linear regression model with a stepwise selection protocol was used to identify an optimal set of land-use pattern predictors. The resulting contributions to the total N concentration were 50% (human-induced land-use intensity), 23.13% (landscape patch-shape complexity), 14.38% (forest and grassland area), and 12.50% (landscape patch-area complexity), respectively. The regression model using land-use measurements can explain 87% of total N variability in the upstream regions of Haihe River. The results indicated that human-related land-use factors, such as residential areas, population, and road density, had the most significant effect on N concentration. The agricultural area (30.1% of the study region) was not found to be significantly correlated with total N concentration due to little irrigative farmland and rainfall. Results of the study could help us understand the implications of potential land-use changes that often occur as a result of the rapid development in China.  相似文献   

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