Distribution and activity of bats at local and landscape scales within a rural–urban gradient

We examined the relationship between bat species activity and composition and the extent of forest cover and urbanization in and adjacent to 11 U.S. National Park Service, National Capital Region Parks in Maryland, Virginia, West Virginia, and Washington, D.C., from 2003–2004, using mist nets, harp traps, acoustical detectors, and visual observations in a variety of habitats. Our efforts included 363 trap nights across 74 sites along with acoustical sampling at 362 sites. We captured 383 bats and identified 6,380 echolocation passes of 6 species. Both overall and species-specific activities were affected more by forest fragmentation within parks than by urbanization adjacent to parks. With an ability to exploit anthropogenic structures for day-roosts, big brown bats (Eptesicus fuscus) were the most ubiquitous and probably the most abundant species in NCR Parks, particularly in forested, urban parks. Northern myotis (Myotis septentrionalis), and to a lesser extent, little brown myotis (Myotis lucifugus) were more prevalent in forested, rural parks of the Ridge and Valley and Blue Ridge than in eastern, less forested urban parks of the Piedmont and Coastal Plain physiographic provinces. Retention of larger, residual forest tracts and day-roosting habitat (i.e., trees and snags) would be beneficial to most species, as urban expansion continues throughout the region.     

Characterizing air pollution patterns on multiple time scales in urban areas: a landscape ecological approach

Quantifying the spatiotemporal patterns of air pollution in urban areas is essential for studying ecological processes, environmental quality, and human health in cities. To adequately characterize or monitor air pollution patterns, one important issue is scale because the concentrations of air pollutants are temporally dynamic and spatially heterogeneous. Our research addresses the scale issue in air quality monitoring and analysis by considering the following research questions: (1) How does the spatial pattern of ozone change with the temporal scale of analysis? (2) How does the spatial pattern of PM₁₀ change with the temporal scale of analysis? (3) What implications do these scale effects have for designing and evaluating air pollution monitoring networks? We systematically examined these questions based on data from official air pollution monitoring networks in the Phoenix metropolitan region, Arizona, USA. Our results showed that spatial patterns of both ozone and PM₁₀ may change substantially with the temporal scale of analysis. Ozone patterns at broader (but not finer) temporal scales were more consistent across years, and exhibited a more uniform, regionalized pattern. PM₁₀ patterns were less consistent across years than ozone, and exhibited a more localized effect. Spatial patterns of PM₁₀ also varied seasonally. Our study demonstrates that it is critically important to consider the temporal and spatial scales in designing or evaluating air monitoring networks in particular and in conducting air pollution research in general.     

Silphids in urban forests: Diversity and function

Many ecologists have examined the process of how urbanization reduces biological diversity but rarely have its ecological consequences been assessed. We studied forest-dwelling burying beetles (Coleoptera: Silphidae)—a guild of insects that requires carrion to complete their life cycles—along an urban-rural gradient of land use in Maryland. Our objective was to determine how forest fragmentation associated with urbanization affects (1) beetle community diversity and structure and (2) the ecological function provided by these insects, that is, decomposition of vertebrate carcasses. Forest fragmentation strongly reduced burying beetle diversity and abundance, and did so far more pervasively than urbanization of the surrounding landscape. The likelihood that beetles interred experimental baits was a direct, positive function of burying beetle diversity. We conclude that loss of burying beetle diversity resulting from forest fragmentation could have important ecological consequences in urban forests.     

Forest ethnography: An approach to study the environmental history and political ecology of urban forests

Urban Ecosystems - A landscape succession paradigm has shaped much of our understanding about the processes of forest emergence and transformation in the United States. Drawing heavily from theory...     

Components of landscape pattern and urban biodiversity in an era of climate change: a global survey of expert knowledge

There is sufficient evidence to show that both humans and fauna are profoundly affected by landscape pattern composition and configuration in relation to adaptation to climate change impacts in urban landscapes. Despite this, global-scale research that ranks which components of landscape pattern play the most pivotal roles in this process is absent. Also lacking is in-depth examination of the potential areas of conflict between biodiversity conservation targets and those that pertain to human dimensions of climate change adaptation goals in relation to landscape patterns. The research aim was to determine how to identify, rank, and weight the most important components of landscape pattern affecting urban biodiversity in the changing climate and how to address areas of conflict between biodiversity conservation and human dimensions of climate change adaptation goals in terms of the spatial patterning of land cover classes distributed across urban landscapes. To do this, a global survey of 87 participants from 69 academic centres involved in at least 325 research projects between 2000 and 2017 was conducted. Of the eight components of landscape pattern identified and ranked by participants worldwide, the three most important components are respectively patch size, connectivity and proximity, and land cover heterogeneity. This research reveals that opinions of participants with experience in conducting research in the Southern Hemisphere in general and Oceania in particular influence this ranking. While a range of recommendations from specialists have been gathered and weighted, there is still much more research required to address areas of conflict between what fauna and humans need in the face of climate change.     

Detecting the scales at which birds respond to structure in urban landscapes

Little empirical information exists about how birds respond to urban landscape structure across multiple scales. We explored how the variation in percent tree canopy cover, at four different scales, affected the abundance of bird species across various urban sites in North America. Bird counts were derived from previous studies, and tree patches were measured from aerial photographs that represented areas of 0.2 km², 1.5 km², 25.0 km², and 85.0 km². At each of the four areas, we conducted regressions between bird counts and percent cover of various tree patch sizes. From these analyses, we determined the area (called the best prediction area—BPA) and the patch size (called the best patch size—BPS) that accounted for a significant amount of the variation in bird counts, beyond the variation accounted for by these parameters measured at other scales. BPA and BPS were calculated primarily to take into account the high degree of collinearity that existed among the amount of tree canopy cover measured across the four scales.We calculated BPA and BPS values for a variety of bird species and ascertained whether larger species had relatively larger BPS and BPA values. In the spring, middle-sized to large birds (16.6 g–184.0 g) had relatively larger BPS values than did smaller birds (3.2 g–16.5 g), but in the summer, the largest birds (61.7 g–576.0 g) had small BPS values. Spring BPA values showed a similar result but summer BPA values did not. A majority of birds of all sizes had summer BPA values at the finer scales of 0.2 km² and 1.5 km². Overall, body size was an approximate predictor of the area and patch size at which a species responds to trees in a landscape, but many exceptions did occur. These exceptions could be related to a variety of factors, one being the difficulty in relating human-biased measurements to avian measurements of a landscape. The method described in this study will help researchers design multi-scale studies to address the effect of landscape pattern on different animal species.     

Informing and forming preferences in environmental valuation: Coral reef biodiversity

The level and depth of information provision required for making informed judgements over environmental options has remained troublesome in various contexts from individual choice through to international policy. In the valuation literature concern has been expressed for ‘information bias’ leading to distorted estimates of the worth of environmental entities (e.g. wildlife, ecosystems) because peoples intentions are formed during the valuation process by the information provided. Contending psychological models on the role of information and its relationship to ethical concerns are reviewed with respect to public decision processes over environmental entities. The robustness of pre-existing environmental preferences is then linked to ethical positions but their role is unclear. Empirical evidence is reported from a contingent valuation method study of coral reef biodiversity on the strong connections between informing and forming preferences and specific ethical beliefs regarding environmental entities.     

A GIS for environmental assessment of air pollution impacts on urban clusters and natural landscape at Rosetta City and region,Egypt

An air pollution problem is taking place in the Rosetta region resulting from the brick industry. Polluting point sources cause plumes that disperse by the prevailing wind, covering urban areas of Rosetta City and surrounding landscape of agricultural fields. A model for pollutants plumes was designed through a GIS to calculate the dispersal of total suspended particulate (TSP) loads over the landscape and to estimate its spatial distribution and to analyze its relationship with other geographic land use attributes.TSP pollutant concentrations starting from 100 g/m³ cover more than 34 km² of sensitive land cover through all the year. A concentration level of 100 g/m³ affects about 93% of the sensitive palm trees cultivation, 47% of cultivated land, and 92% of urban areas. TSP concentration level of 200 g/m³ was found to be affecting the same percentage of built-up urban areas.Concentration levels exceed the permissible limits mentioned in the Egyptian law of environment (90 g/m³). The situation is hygienically deteriorated, and large areas of agricultural land are strongly affected or subjected to future impact. Recommended measures are mostly involved with transferring this industrial activity to a safer location at the southwest of the city. The study proposes that brick mills sites on the river Nile bank be utilized for urban development projects and for the promotion of tourism.     

Birds and the urban environment: the value of green walls

The simplest form of a ‘green wall’ is where self-adhering climbing plants colonise vertical surfaces, an approach that has been used on buildings for millennia (Koehler 2008). Green walls in urban areas are now well-known for their insulation and air cleaning capacities, but little is known of their value as habitats for wildlife. This paper presents preliminary findings of their value for urban birds. The abundance of birds, on 27 green walls and within the area enclosed by a semi-circle of 10 m radius immediately surrounding them, was compared with 27 walls without vegetation (bare walls) and similar surroundings. The study was carried out during the summer and winter of 2010–11 in north Staffordshire (UK). Birds exploited the green walls for various reasons (including nesting, food and shelter) but were never found on bare control walls. The roofs of buildings and the surrounding vegetation were used by birds in both regimes, but birds were more abundant in areas with green walls. The use of green walls by birds depended on the time of day, the season and whether the vegetation was evergreen or deciduous. The birds’ activity was always restricted to the upper half of the wall vegetation. Green walls and the immediate surroundings were used by some species of conservation concern in Great Britain (e.g. Passer domesticus and Sturnus vulgaris). Therefore, encouraging householders and businesses to grow vegetation up walls may be an effective way of providing a range of resources for birds in urban areas without the need for expensive additional land-take.     

Cosmopolitanization in action: connecting scales in international environmental organizations

In this article we analyse how professionals in two international environmental organizations (IEOs) concerned with biodiversity act as ‘entrepreneurs of cosmopolitanization’ by establishing connections between the various scales they mobilize in their daily work. Drawing on an empirical survey, we show that these professionals mobilize a range of activities to meet a twofold requirement. The first requirement is for universality, which corresponds to their status, their determination to adopt a scientific approach and to the scale at which they initially defined the problem of biodiversity loss. The second requirement is to embed in specific contexts. Tension between these two types of requirement is inevitable. It is inherent in the cosmopolitan perspective and leads to contextual arrangements between the global approach to environmental problems and the forging of alliances with national, regional or local institutions and actors, according to opportunities and requirements. Connecting the various scales of environmental action unavoidably remains a partially achieved objective.     

Vegetation management and benthic macroinvertebrate communities in urban stormwater ponds: implications for regional biodiversity

Urban Ecosystems - Designed ecosystems (e.g., gardens or engineered ponds) are increasingly common components of urban landscapes and contribute valuable ecosystem services. However, management of...     

Pollution and perception: Social visibility and local environmental mobilization

Why does local environmental degradation lead some communities to rebel while others remain politically complacent? This comparative analysis seeks a partial answer to that question through examination of the impacts of the social visibility of local environmental problems on political mobilization in the Great Lakes Basin. The data upon which this paper is based is drawn from original field research conducted in six environmentally contaminated communities in both the U.S. and Canada. The paper examines the efforts of industry, government and environmental organizations to manipulate the visibility of contaminants in order to promote or prevent the emergence of grass roots political activism. However, the data indicates that socially visible environmental disorganization increases local awareness of contamination, but has little bearing on the definition of that contamination as a problem requiring political action. The transformation of awareness of environmental problems into local political mobilization is not determined primarily by the social visibility of contaminants, their sources, or their impacts on the environment.     

Determinants of urban tree canopy in residential neighborhoods: Household characteristics, urban form, and the geophysical landscape

The aesthetic, economic, and environmental benefits of urban trees are well recognized. Previous research has focused on understanding how a variety of social and environmental factors are related to urban vegetation. The aim is often to provide planners with information that will improve residential neighborhood design, or guide tree planting campaigns encouraging the cultivation of urban trees. In this paper we examine a broad range of factors we hypothesize are correlated to urban tree canopy heterogeneity in Salt Lake County, Utah. We use a multi-model inference approach to evaluate the relative contribution of these factors to observed heterogeneity in urban tree canopy cover, and discuss the implications of our analysis. An important contribution of this work is an explicit attempt to account for the confounding effect of neighborhood age in understanding the relationship between human and environmental factors, and urban tree canopy. We use regression analysis with interaction terms to assess the effects of 15 human and environmental variables on tree canopy abundance while holding neighborhood age constant. We demonstrate that neighborhood age is an influential covariate that affects how the human and environmental factors relate to the abundance of neighborhood tree canopy. For example, we demonstrate that in new neighborhoods a positive relationship exists between street density and residential tree canopy, but the relationship diminishes as the neighborhood ages. We conclude that to better understand the determinants of urban tree canopy in residential areas it is important to consider both human and environmental factors while accounting for neighborhood age.     

Modeling urban landscape dynamics: A case study in Phoenix,USA

Urbanization has profoundly transformed many landscapes throughout the world, and the ecological consequences of this transformation are yet to be fully understood. To understand the ecology of urban systems, it is necessary to quantify the spatial and temporal patterns of urbanization, which often requires dynamic modeling and spatial analysis. In this paper, we describe an urban growth model, the Phoenix Urban Growth Model (PHX-UGM), illustrate a series of model calibration and evaluation methods, and present scenario-based simulation analyses of the future development patterns of the Phoenix metropolitan region. PHX-UGM is a spatially explicit urban landscape model and is a modified version of the Human-Induced Land Transformations (HILT) model originally developed for the San Francisco Bay Area. Using land use and other data collected for the Phoenix area, existing growth rules were selectively modified and new rules were added to help examine key ecological and social factors. We used multiple methods and a multi-scale approach for model calibration and evaluation. The results of the different evaluation methods showed that the model performed reasonably well at a certain range of spatial resolutions (120–480 m). When fine-scale data are available and when landscape structural details are desirable, the 120-m grain size should be used. However, at finer levels the noise and uncertainty in input data and the exponentially increased computational requirements would considerably reduce the usefulness and accuracy of the model. At the other extreme, model projections with too coarse a spatial resolution would be of little use at the local and regional scales. A series of scenario analyses suggest that the Metropolitan Phoenix area will soon be densely populated demographically and highly fragmented ecologically unless dramatic actions are to be taken soon to significantly slow down the population growth. Also, there will be an urban morphological threshold over which drastic changes in certain aspects of landscape pattern occur. Specifically, the scenarios indicate that, as large patches of open lands (including protected lands, parks and available desert lands) begin to break up, patch diversity declines due partly to the loss of agricultural lands, and the overall landscape shape complexity also decreases because of the predominance of urban lands. It seems that reaching such a threshold can be delayed, but not avoided, if the population in the Phoenix metropolitan region continues to grow. PHX-UGM can be used as a tool for exploring the outcome of different urban planning strategies, and the methods illustrated in this paper can be used for evaluating other urban models.     

Forest structure and anthropogenic disturbances regulate plant invasion in urban forests

Urban forest ecosystems, the structure, and functions therein are subjected to anthropogenic disturbances. Native and sensitive species from those forests might be lost due to such disturbances. At the same time, supplemented anthropogenic resources might create opportunities for exotic and invasive species. Although invasive species are considered one of the major threats to the urban biodiversity and ecosystems, the research on invasion dynamics in the Himalayas has primarily focused on the impacts of invasion on forest structure and productivity. This study aims to understand the influence of forest structure and anthropogenic factors in invasion success that are poorly covered in the existing literature. We selected 11 urban forest patches for the study considering the presence-absence of selected invasive species and structural attributes. We used Principal Component Analysis (PCA) to reduce co-linearity in the covariates and generalized linear mixed effects model (GLMM) to identify the factors affecting invasion success. We found that forest structural attributes, namely, tree diameter, height and canopy cover, and anthropogenic disturbances regulate invasion success in urban forests. This implies that maintaining urban forest structural attributes, especially the stands with large-sized trees, is essential to control invasion in the context of urbanization.

     

Diversity and structure of urban forests of Sahel cities in Niger

Urban Ecosystems - Urbanization in the Sahel is constantly competing with and greatly affecting the woody flora in urban areas. Urbanization can replace the species mix, leading to changes in plant...     

Ecological consequences of fragmentation and deforestation in an urban landscape: a case study

Landscape change is an ongoing process even within established urban landscapes. Yet, analyses of fragmentation and deforestation have focused primarily on the conversion of non-urban to urban landscapes in rural landscapes and ignored urban landscapes. To determine the ecological effects of continued urbanization in urban landscapes, tree-covered patches were mapped in the Gwynns Falls watershed (17158.6?ha) in Maryland for 1994 and 1999 to document fragmentation, deforestation, and reforestation. The watershed was divided into lower (urban core), middle (older suburbs), and upper (recent suburbs) subsections. Over the entire watershed a net of 264.5 of 4855.5?ha of tree-covered patches were converted to urban land use??125 new tree-covered patches were added through fragmentation, 4 were added through reforestation, 43 were lost through deforestation, and 7 were combined with an adjacent patch. In addition, 180 patches were reduced in size. In the urban core, deforestation continued with conversion to commercial land use. Because of the lack of vegetation, commercial land uses are problematic for both species conservation and derived ecosystem benefits. In the lower subsection, shape complexity increased for tree-covered patches less than 10?ha. Changes in shape resulted from canopy expansion, planted materials, and reforestation of vacant sites. In the middle and upper subsections, the shape index value for tree-covered patches decreased, indicating simplification. Density analyses of the subsections showed no change with respect to patch densities but pointed out the importance of small patches (??5?ha) as ??stepping stone?? to link large patches (e.g., >100?ha). Using an urban forest effect model, we estimated, for the entire watershed, total carbon loss and pollution removal, from 1994 to 1999, to be 14,235,889.2?kg and 13,011.4?kg, respectively due to urban land-use conversions.     

Amphibian use of constructed and remnant wetlands in an urban landscape

Urban areas are increasing in number, extent, and human population density worldwide. There is potential to mitigate negative impacts of urbanization to native pond-breeding amphibians by providing habitat in both remnant natural and constructed wetlands. This study examines amphibian use of potential breeding sites in natural and constructed ponds in a large metropolitan area to investigate habitat characteristics that are associated with successful breeding. I surveyed 62 ponds over three breeding seasons in Portland, Oregon, measuring eleven habitat characteristics that may influence their successful breeding: pond depth, nitrate level, aquatic refugia, aquatic vegetation, surrounding vegetation, pond permanence, presence of fish and of introduced bullfrogs, surrounding road density and forest cover, and whether they were constructed or remnant natural ponds. Five of the six native pond-breeding species that occur in the region were regularly found breeding in city ponds. Surrounding forest cover and amount of aquatic vegetation were highly associated with breeding, indicating that preserving and planting vegetation likely benefits urban amphibians. Non-native bullfrogs were not associated with native species richness. Surprisingly, whether a pond was natural or constructed was also only weakly associated with native species breeding, and the trend was towards higher presence for all species in constructed ponds. This indicates that novel, human-dominated areas can provide habitat for these species. Consideration of habitat characteristics associated with breeding success in urban pond management will likely benefit native amphibians in these rapidly expanding landscapes.