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1.
We formulated and tested models of relationships among determinants of vegetation cover in two agroforested landscapes of eastern North America (Haut Saint-Laurent, Quebec, Canada) that differed by the spatial arrangement of their geomorphic features and intensity of agricultural activities. Our landscape model compared the woody plots of each landscape in terms of the relative influence of environmental attributes, land use history (1958 – 1997), and spatial context (i.e., proximity of similar or contrasting land cover). Our vegetation model evaluated the relative contribution of the same sets of variables to the distributions of herbs, trees, and shrubs. Relationships were assessed using partial Mantel tests and path analyses. Significant environmental and contextual differences were found between the vegetation plots of the two landscapes, but disturbance history was similar. Our vegetation model confirms the dominant effect of historical factors on vegetation patterns. Whereas land-use history overrides environmental and contextual control for trees, herbaceous and shrub species are more sensitive to environmental conditions. Context is determinant only for understory species in older, less-disturbed plots. Results are discussed in relevance to vegetation dynamics in a landscape perspective that integrates interactions between environmental and human influences.  相似文献   

2.
Changes in key drivers (e.g., climate, disturbance regimes and land use) may affect the sustainability of forest landscapes and set the stage for increased tension among competing ecosystem services. We addressed two questions about a suite of supporting, regulating and provisioning ecosystem services in each of two well-studied forest landscapes in the western US: (1) How might the provision of ecosystem services change in the future given anticipated trajectories of climate, disturbance regimes, and land use? (2) What is the role of spatial heterogeneity in sustaining future ecosystem services? We determined that future changes in each region are likely to be distinct, but spatial heterogeneity (e.g., the amount and arrangement of surviving forest patches or legacy trees after disturbance) will be important in both landscapes for sustaining forest regeneration, primary production, carbon storage, natural hazard regulation, insect and pathogen regulation, timber production and wildlife habitat. The paper closes by highlighting five general priorities for future research. The science of landscape ecology has much to contribute toward understanding ecosystem services and how land management can enhance—or threaten—the sustainability of ecosystem services in changing landscapes.  相似文献   

3.
Environmental and green justice problems occur globally, especially in cities with unequal access to urban greenspaces. Recently, inequality in school greenspaces has drawn growing attention, given the importance of campus green environments in young students’ health and academic performance. However, the commonly used Normalized Differences Vegetation Index (NDVI) method for measuring greenspace from satellite imagery is hindered by the saturation issue and tend to underestimate greenspace at high vegetation cover areas, causing large uncertainties in greenspace inequality studies at a national scale. Besides, despite the progress on the inequality of public greenspace exposure, our understandings of primary school greenspace provision and inequality, as well as the driving factors, for young students in a developing world (e.g., China) is still limited. To address these issues, we first adapted a spectral unmixing technique based on multi-sensor remote sensing for more accurate measurements of greenspace provision. Then, we evaluated the provision and inequality of greenspace for 19,681 primary schools in China’s 31 major cities and examined the driving factors using an integrated path analysis. Our findings revealed that: (1) Our proposed multi-sensor remote sensing-based method for greenspace measurement is reliable across our study area with a R2 of 0.81 and RMSE of 0.14; in contrast, the traditional NDVI-based greenspace measurement saturated at the range of 0.7–1.0, leading to much lower accuracy (a R2 of 0.72 and RMSE of 0.24). (2) Most of the cities under study had low to moderate levels of inequality in primary school greenspace (Gini index < 0.5), but the overall greenspace provision was relatively low; Five cities under study facing high inequality in greenspace exposure (Gini index ≥ 0.5) as well as low greenspace provision (mean fraction cover < 0.25). (3) The monthly maximum temperature and the mean cover of greenspace in primary schools were identified as variables directly affecting the inequality in primary school greenspace (R2 = 0.76, p-value < 0.05), whereas the city-level government revenue manifests its effects through the mean cover of greenspace in primary schools and city-level mean greenspace cover. By developing a novel framework for examining the provision and inequality of greenspace in all primary schools in China’s major cities, our study provides valuable insights for designing and evaluating school greening programs in support of healthier learning environment development for next generations.  相似文献   

4.
Urban forests provide multiple ecosystem services, including particulate matter (PM) air pollution removal. While previous studies have assessed relationships between atmospheric PM concentrations and urban land use and land cover, few studies have modeled PM removal by trees in relation to urban form (e.g., topography, land use, land cover, and proximity to emission sources). Particulate matter is a mixture of particles, including black carbon (BC), a byproduct of incomplete fossil fuel and biomass combustion with strong warming potential and linked to adverse health outcomes. We coupled empirical BC deposition data, collected from urban trees in Denton, Texas, with 226 urban form variables to generate land use regression models of annual and seasonal BC removal. Annual and seasonal models revealed emission source proxies, terrain exposure towards emission sources, and topographic exposure as influential to BC removal by trees. Regression equations were applied at one-meter resolution to estimate the BC removal potential of tree planting across the city. The resultant maps, which show regions of probable high and low BC removal by trees, can be used by arborists, urban foresters, landscape architects, and urban planners to inform urban forest design, planning, and decision-making.  相似文献   

5.
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   

6.
Green infrastructure (GI) provides a suite of ecosystem services that are widely recognized as critical to health, well-being, and sustainability on an urbanizing planet. However, the distribution of GI across urban landscapes is frequently uneven, resulting in unequal delivery of these services to low-income residents or those belonging to underserved racial/ethnic identities. While GI distribution has been identified as unequal across municipalities, we investigated whether this was true in public schoolyards within and among urban school districts. We examined schoolyards in four metropolitan areas of diverse socio-economic and demographic compositions in North Carolina, USA to determine if they provided equal exposure to GI, then compared whether this was true of the broader urban landscape. We first classified the land cover of elementary schoolyards and their neighborhoods, then used bivariate and multivariate approaches to analyze the relationships between GI (i.e. tree canopy cover and total GI) and the socioeconomic status and race/ethnicity of the schools and surrounding neighborhoods, respectively. We found that the extent of tree canopy cover and total GI in schoolyards was unrelated to the socioeconomic status and the race/ethnicity of students across the four school districts. In contrast, neighborhoods with lower socioeconomic status and larger populations of underserved race/ethnicity residents had less tree canopy cover and total GI. Although total GI was more evenly distributed in schoolyards, the extent of tree canopy cover and total GI in schoolyards was lower than that in the neighborhoods. This suggests opportunities for school districts to expand GI in schoolyards, leveraging their potential to increase ecosystem services to all children, from increased educational opportunities to improved mental, physical, and environmental well-being.  相似文献   

7.
Green spaces play a vital role in the social, economic, and physical well-being of people. To further research on this topic, in this paper, we estimated the association of greenness and academic performance at the school-level in Brazil. We analyzed this association using mixed-effects regression models, adjusted for air pollution, SES, and spatiotemporal terms. We used the Normalized Difference Vegetation Index (NDVI) as the exposure variable. Data from the high school national exam in Brazil (at the school level, measured with a score varying from 0 to 1000) was used to represent the academic performance. The primary analysis results indicate that green areas surrounding schools are positively associated with school-level academic performance in math, with an estimated coefficient of 17.18 (95%CI: 10.46; 23.90). The results were statistically insignificant for science, with a coefficient of − 2.39 (95%CI: −7.49; 2.71). Our findings are relevant for policymakers and urban planners to improve the environment surrounding schools to promote public health by making schools healthier.  相似文献   

8.
Increasing land ownership fragmentation in the United States is causing concerns with respect to its ecological implications for forested landscapes. This is especially relevant given that human influence is one of the most significant driving forces affecting the forest landscape. A method for generating realistic land ownership maps is needed to evaluate the effects of ownership fragmentation on forest landscapes in combination with other natural processes captured in forest process models. Ownership patterns from human activities usually generate landscape boundary shapes different from those arising from natural processes. Spatial characteristics among ownership types – e.g., private, public ownership – may also differ. To address these issues, we developed the Fragmented Land Ownership Spatial Simulator (FLOSS) to generate ownership patterns that reflect the Public Land Survey System (PLSS) shapes and various patch size distributions among different types of ownership (e.g., private, public). To evaluate FLOSS performance, we compared the simulated patterns with various ownership fragmentation levels to the actual ownership patterns in the Missouri Ozarks by using selected landscape indices. FLOSS generated landscapes with spatial characteristics similar to actual landscapes, suggesting that it can simulate different levels of ownership fragmentation. This will allow FLOSS to serve as a feasible tool for evaluating forest management applications by spatially allocating various management scenarios in a realistic way. The potentials and limitations of FLOSS application are discussed.  相似文献   

9.
Urban green infrastructure supports resilience in cities and promotes sustainable resource management. Small green areas, including school green areas (SGAs), are an important component of urban green infrastructure, playing a key role in supplying cities with educational services. This article describes how SGAs can amplify an urban green area's connectivity and multifunctionality. The analysis was performed in Bucharest as a case study. A survey based on questionnaires was used to obtain data regarding green spaces within public schools. A total of 411 administrators from 461 public schools participated in the survey for a response rate of 89.1%. Information from the questionnaires was augmented with spatial data of SGAs and public green spaces, i.e., parks and city gardens. Using parametric and nonparametric statistical analysis, we first identified the variables that determine an SGA's presence and size. Potential connectivity assessment results showed that most of the schools that lack or have small-sized SGAs have the possibility to cover their green space deficit by developing activities within nearby public green spaces. A structural connectivity assessment of SGAs toward other public urban green areas revealed that SGAs are an important element of the urban environment by serving as stepping stones to species flow. The multifunctionality of the SGAs was emphasized through the educational services they provide, being involved in pupils’ daily activities. The increased connectivity and multifunctionality of urban green infrastructure through small, specialized green areas, such as SGAs, is an indicator of the fact that such areas can be used to ameliorate the deficit of green space in major urban areas.  相似文献   

10.
The presence of green spaces has been associated with improved physical health and better mental health and wellbeing. In contrast, the presence of gray features including build-up areas might have a negative impact on the health and wellbeing of citizens. To date, the available evidence on the health effects of green and gray spaces have mainly relied on 2-dimensional (2D) indicators of these spaces such as land use maps or, more recently, satellite derived indices (e.g., green space indices such as normalized difference vegetation index (NDVI) or gray space indices such as imperviousness). Although they are acceptable proxies of these exposures, 2D indicators could have inaccuracies when characterizing diverse set of vegetation types in combination with different types of gray spaces, which is typical of urban environments. To overcome this gap, we developed a set of three-dimensional (3D) indicators derived mainly from airborne LiDAR (Light Detection and Ranging) acquired in 2008 and 2010 over the metropolitan area of Rome (Italy). In particular, we extracted volume of green features such as shrubs and trees (Green volume [m3/ha]), volume of buildings (Gray volume[m3/ha]), a novel index called Normalized Difference Green-Gray Volume index (NDGG) as well as indicators of the tree count. We compared the 3D indicators with two widely used 2D indicators for characterizing green and gray spaces (i.e., NDVI and imperviousness) in different buffers around 79140 address points in the city. For the green indicators, we found that the Pearson correlations between NDVI and Green Volume were 0.47 (50 m buffer) and 0.33 (300 m buffer) while the correlations between NDVI and number of trees were 0.56 (50 m buffer) and 0.58 (300 m buffer). For gray indicators, the correlations between imperviousness and gray volume were 0.62 (50 m buffer) and 0.79 (300 m buffer). For NDGG, the correlations were higher with both NDVI (0.76 and 0.83 for 50 m and 300 m buffers) and imperviousness (−0.75 and −0.83 for 50 m and 300 m buffers). Our results showed that the use of 3D indicators can have potential benefits, especially regarding green features which can be highly heterogeneous in complex urban landscapes such as the city of Rome.  相似文献   

11.

Context

Developing species distribution models (SDMs) to detect invasive species cover and evaluate habitat suitability are high priorities for land managers.

Objectives

We tested SDMs fit with different variable combinations to provide guidelines for future invasive species model development based on transferability between landscapes.

Methods

Generalized linear model, boosted regression trees, multivariate adaptive regression splines, and Random Forests were fit with location data for high cheatgrass (Bromus tectorum) cover in situ for two post-burn sites independently using topographic indices, spectral indices derived from multiple dates of Landsat 8 satellite imagery, or both. Models developed for one site were applied to the other, using independent cheatgrass cover data from the respective ex situ site to test model transferability.

Results

Fitted models were statistically robust and comparable when fit with at least 200 cover plots in situ and transferred to the ex situ site. Only the Random Forests models were robust when fit with a small number of cover plots in situ.

Conclusions

Our study indicated spectral indices can be used in SDMs to estimate species cover across landscapes (e.g., both within the same Landsat scene and in an adjacent Landsat scene). Important considerations for transferability include the model employed, quantity of cover data used to train/test the models, and phenology of the species coupled with the timing of imagery. The results also suggest that when cover data are limited, SDMs fit with topographic indices are sufficient for evaluating cheatgrass habitat suitability in new post-disturbance landscapes; however, spectral indices can provide a more robust estimate for detection based on local phenology.
  相似文献   

12.
Mature trees provide a range of ecosystem services in urban landscapes, represent important wildlife habitat, and impact positively on human wellbeing. However, mature trees are perceived as a risk to people and infrastructure and occupy land suitable for development. Trees are slow to reach ecological maturity and thus difficult to replace when removed. In this study, we: (a) quantified native canopy cover retained during residential development using aerial imagery; (b) identified where native trees are/are not retained within residential developments with a focus on mature trees; and (c) evaluated the effectiveness of current legal mechanisms for protecting native trees during residential development. Native canopy cover was reduced by 49% during residential development. Mature trees had the highest probability of retention within residential developments if they occurred within intact remnant vegetation. A lower probability of retention for mature trees was observed in urban green space, and almost no mature trees were retained in other areas within residential developments, such as residential blocks and road verges. Mature trees had greater probability of retention where the jurisdiction offered some legislative protection. The loss of mature trees during residential development could be reduced with a greater focus on avoiding the removal of existing trees during the planning stage rather than offsetting the impacts elsewhere; and by designing green space within residential developments to ensure adequate separation between mature trees and people and infrastructure.  相似文献   

13.
Urban forests are increasingly valued for multiple benefits such as amenity, cultural values, native biodiversity, ecosystem services, and carbon sequestration. Urban biodiversity in particular, is the new focus although global homogenisation is undermining regional differentiation. In the northern hemisphere (e.g., Canada and USA) and in the southern hemisphere, particularly in countries like South Africa, Australia, South America and New Zealand, local biodiversity is further impacted by historical colonisation from Europe. After several centuries, urban forests are now composed of synthetic and spontaneous mixtures of native species, and exotic species from around the temperate world (e.g., Europe, North and South America, South Africa, Asia). As far as we are aware no-one has carried out in-depth study of these synthetic forests in any Southern Hemisphere city. Here we describe the composition, structure, and biodiversity conservation imperatives of urban temperate forests at 90 random locations in Christchurch city, New Zealand.We document considerable plant diversity; the total number of species encountered in the 253 sampled urban forest patches was 486. Despite this incredibly variable data set, our ability to explain variation in species richness was surprisingly good and clearly indicates that total species richness was higher in larger patches with greater litter and vegetation cover, and taller canopy height. Species richness was also higher in patches surrounded by higher population densities and closer to very large native forest patches. Native species richness was higher in patches with higher soil pH, lower canopy height, and greater litter cover and in patches closer to very large native forest patches indicating dispersal out of native areas and into gardens. Eight distinct forest communities were identified by Two-Way INdicator SPecies ANalysis (TWINSPAN) using the occurrence of 241 species that occurred in more than two out of all 253 forest patches.Christchurch urban forest canopies were dominated by exotic tree species in parklands and in street tree plantings (linear parkland). Native tree and shrub species were not as common in public spaces but their overall density high in residential gardens. There was some explanatory power in our data, since less deprivation resulted in greater diversity and density, and more native species, which in turn is associated with private ownership. We hypothesise that a number of other factors, which were not well reflected in our measured environmental variables, are responsible for much of the remaining variation in the plant community structure, e.g., advertising, peoples choice. For a more sustainable asset base of native trees in New Zealand cities we need more, longer-lived native species, in large public spaces, including a greater proportion of species that bear fruit and nectar suitable for native wildlife. We may then achieve cities with ecological integrity that present multiple historical dimensions, and sequester carbon in legible landscapes.  相似文献   

14.

Context

Pasture-woodlands are semi-natural landscapes that result from the combined influences of climate, management, and intrinsic vegetation dynamics. These landscapes are sensitive to future changes in land use and climate, but our ability to predict the impact on ecosystem service provisioning is limited due to the disparate scales in time and space that govern their dynamics.

Objectives

To develop a process-based model to simulate pasture-woodland landscapes and the provisioning of ecosystem services (i.e., livestock forage, woody biomass and landscape heterogeneity).

Methods

We modified a dynamic forest landscape model to simulate pasture-woodland landscapes in Switzerland. This involved including an annual herbaceous layer, selective grazing from cattle, and interactions between grazing and tree recruitment. Results were evaluated within a particular pasture, and then the model was used to simulate regional vegetation patterns and livestock suitability for a ~198,000 ha landscape in the Jura Vaudois region.

Results

The proportion of vegetation cover types at the pasture level (i.e., open, semi-open and closed forests) was well represented, but the spatial distribution of trees was only broadly similar. The entire Jura Vaudois region was simulated to be highly suitable for livestock, with only a small proportion being unsuitable due to steep slopes and high tree cover. High and low elevation pastures were equally suitable for livestock, as lower forage production at higher elevations was compensated by reduced tree cover.

Conclusions

The modified model is valuable for assessing landscape to regional patterns in vegetation and livestock, and offers a platform to evaluate how climate and management impact ecosystem services.
  相似文献   

15.
Land cover and land use changes can have a wide variety of ecological effects, including significant impacts on soils and water quality. In rural areas, even subtle changes in farming practices can affect landscape features and functions, and consequently the environment. Fine-scale analyses have to be performed to better understand the land cover change processes. At the same time, models of land cover change have to be developed in order to anticipate where changes are more likely to occur next. Such predictive information is essential to propose and implement sustainable and efficient environmental policies. Future landscape studies can provide a framework to forecast how land use and land cover changes is likely to react differently to subtle changes. This paper proposes a four step framework to forecast landscape futures at fine scales by coupling scenarios and landscape modelling approaches. This methodology has been tested on two contrasting agricultural landscapes located in the United States and France, to identify possible landscape changes based on forecasting and backcasting agriculture intensification scenarios. Both examples demonstrate that relatively subtle land cover and land use changes can have a large impact on future landscapes. Results highlight how such subtle changes have to be considered in term of quantity, location, and frequency of land use and land cover to appropriately assess environmental impacts on water pollution (France) and soil erosion (US). The results highlight opportunities for improvements in landscape modelling.  相似文献   

16.
Single-family residential neighborhoods make up large areas within cities and are undergoing change as residences are renovated and redeveloped. We investigated the effects of such residential redevelopment on land cover (trees/shrubs, grass, building, and hardscape) in the 20 largest cities in the Los Angeles Basin from 2000 to 2009. We identified spatially stratified samples of single-family home lots for which additional square footage was recorded and for which additional construction was not recorded by the tax assessor. We then digitized land cover on high-resolution color imagery for two points in time to measure land cover change. Redevelopment of single-family homes in Los Angeles County resulted in a significant decrease in tree/shrub and grass cover and a significant increase in building and hardscape area. Over 10 years, urban green cover (trees/shrubs and grass) declined 14–55% of green cover in 2000 on lots with additional recorded development and 2–22% of green cover in 2000 for single-family lots for which new permits were not recorded. Extrapolating the results to all single-family home lots in these cities indicate a 1.2 percentage point annual decrease in tree/shrub cover (5.6% of existing tree/shrub cover) and a 0.1 percentage point annual decrease in grass cover (2.3% of existing grass cover). The results suggest that protection of existing green cover in neighborhoods is necessary to meet urban forest goals, a factor that is overlooked in existing programs that focus solely on tree planting. Also, changing social views on the preferred size of single-family homes is driving loss of tree cover and increasing impervious surfaces, with potentially significant ramifications for the functioning of urban ecosystems.  相似文献   

17.
Quantifying landscape dynamics is a central goal of landscape ecology, and numerous metrics have been developed to measure the influence of human activities on natural landscapes. Composite scores that characterize human modifications to landscapes have gained widespread use. A parsimonious alternative is to estimate the proportion of a cover type (i.e. natural) within a spatial neighborhood to characterize both compositional and structural aspects of natural landscapes. Here I extend this approach into a multi-scale, integrated metric and apply it to national datasets on land cover, housing density, road existence, and highway traffic volume to measure the dynamics of natural landscapes in the conterminous US. Roughly one-third of the conterminous US (2.6 million km2) in 1992 was classified as human-dominated. By 2001 this expanded by 80,800 km2, and forecasted residential growth by 2030 will potentially lead to an additional loss of up to 92,200 km2. Wetland cover types were particularly affected. The natural landscapes metric developed here provides a simple, robust measure of landscape dynamics that has a direct physical interpretation related to proportion of natural habitat affected at a location, represents landscapes as a gradient of conditions rather predicated on patch/matrix definition, and measures the spatial context of natural areas.  相似文献   

18.
在滨海盐碱地区的园林绿化中,采用大穴植树技术,按照“适地适树”的原则科学选择树种,壮苗带土球栽植,做好穴面土壤覆盖,既能保证树木成活,又能使穴内土壤含盐量逐渐下降,从而保证树木不受盐碱危害,生长旺盛.该项技术既大大降低了绿化成本,又避免了花坛对地面空间的占有,适用于道路绿化、水库堤岸绿化和其它次要景点绿化.  相似文献   

19.
Brown  Daniel G. 《Landscape Ecology》2003,18(8):777-790
This paper analyzes the interactions between land use and forest cover in the Upper Midwest, USA from 1970 to 1990. New data are presented and interpreted to evaluate the effects of land-use changes, especially abandonment of agriculture and dispersed development, on forest cover throughout the region. Forest-cover data were collected from Landsat satellite imagery and land use was interpreted from aerial photographs for land parcels, based on archival maps of land ownership. In general, forest cover increased throughout the region and throughout the period. Simultaneously, the area used for agriculture declined, much of it being converted to natural uses, and the area of land in low density residential development increased. Forest cover increased most rapidly on low density residential lands and in counties in which a large percentage of homes were for seasonal use (i.e., vacation homes). The data suggest that the transformation of the region from an extractive (i.e., forestry and agriculture) to a recreation-based service economy has played a significant role in the increasing forest cover observed throughout the region. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

20.
Urban forests are unique and highly valued resources. However, trees in urban forests are often under greater stress than those in rural or undeveloped areas due to soil compaction, restricted growing spaces, high temperatures, and exposure to air and water pollution. In addition, conditions change more quickly in urban as opposed to rural and undeveloped settings. Subsequently, proactive management of urban forests can be challenging and requires the availability of current and comprehensive information. Geospatial tools, such as, geographic information systems (GIS), global positioning systems (GPS) and remote sensing, work extremely well together for gathering, analyzing, and reporting information. Many urban forest management questions could be quickly and effectively addressed using geospatial methods and tools. The geospatial tools can provide timely and extensive spatial data from which urban forest attributes can be derived, such as land cover, forest structure, species composition and condition, heat island effects, and carbon storage. Emerging geospatial tools that could be adapted for urban forest applications include data fusion, virtual reality, three-dimensional visualization, Internet delivery, modeling, and emergency response.  相似文献   

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