Urban Woodlands Research Articles

Differential responses to woodland character and landscape context by cryptic bats in urban environments.

Urbanisation is one of the most dramatic forms of land use change which relatively few species can adapt to. Determining how and why species respond differently to urban habitats is important in predicting future biodiversity loss as urban areas rapidly expand. Understanding how morphological or behavioural traits can influence species adaptability to the built environment may enable us to improve the effectiveness of conservation efforts. Although many bat species are able to exploit human resources, bat species richness generally declines with increasing urbanisation and there is considerable variation in the responses of different bat species to urbanisation. Here, we use acoustic recordings from two cryptic, and largely sympatric European bat species to assess differential responses in their use of fragmented urban woodland and the surrounding urban matrix. There was a high probability of P. pygmaeus activity relative to P. pipistrellus in woodlands with low clutter and understory cover which were surrounded by low levels of built environment. Additionally, the probability of recording P. pygmaeus relative to P. pipistrellus was considerably higher in urban woodland interior or edge habitat in contrast to urban grey or non-wooded green space. These results show differential habitat use occurring between two morphologically similar species; whilst the underlying mechanism for this partitioning is unknown it may be driven by competition avoidance over foraging resources. Their differing response to urbanisation indicates the difficulties involved when attempting to assess how adaptable a species is to urbanisation for conservation purposes.

Using electric network theory to model the spread of oak processionary moth, Thaumetopoea processionea, in urban woodland patches

Context Habitat fragmentation is increasing as a result of anthropogenic activities, especially in urban areas. Dispersal through fragmented habitats is key for species to spread, persist in metapopulations and shift range in response to climate change. However, high habitat connectivity may also hasten the spread of invasive species. Objective To develop a model of spread in fragmented landscapes and apply it to the spread of an invasive insect in urban woodland. Methods We applied a patch-based model, based on electric network theory, to model the current and predicted future spread of oak processionary moth (OPM: Thaumetopoea processionea) from its source in west London. We compared the pattern of ‘effective distance’ from the source (i.e. the patch ‘voltage’ in the model) with the observed spread of the moth from 2006 to 2012. Results We showed that ‘effective distance’ fitted current spread of OPM. Patches varied considerably in their ‘current’ and ‘power’ (metrics from the model), which is an indication of their importance in the future spread of OPM. Conclusions Patches identified as ‘important’ are potential ‘pinch points’ and regions of high ‘flow’, where resources for detection and management will be most cost-effectively deployed. However, data on OPM dispersal and the distribution of oak trees limited the strength of our conclusions, so should be priorities for further data collection. This application of electric network theory can be used to inform landscape-scale conservation initiatives both to reduce the spread of invasives and to facilitate large-scale species’ range shifts in response to climate change.

City life makes females fussy: sex differences in habitat use of temperate bats in urban areas.

Urbanization is a major driver of the global loss of biodiversity; to mitigate its adverse effects, it is essential to understand what drives species' patterns of habitat use within the urban matrix. While many animal species are known to exhibit sex differences in habitat use, adaptability to the urban landscape is commonly examined at the species level, without consideration of intraspecific differences. The high energetic demands of pregnancy and lactation in female mammals can lead to sexual differences in habitat use, but little is known of how this might affect their response to urbanization. We predicted that female Pipistrellus pygmaeus would show greater selectivity of forging locations within urban woodland in comparison to males at both a local and landscape scale. In line with these predictions, we found there was a lower probability of finding females within woodlands which were poorly connected, highly cluttered, with a higher edge : interior ratio and fewer mature trees. By contrast, habitat quality and the composition of the surrounding landscape were less of a limiting factor in determining male distributions. These results indicate strong sexual differences in the habitat use of fragmented urban woodland, and this has important implications for our understanding of the adaptability of bats and mammals more generally to urbanization.

Assessing the impact of urbanization on net primary productivity using multi-scale remote sensing data: a case study of Xuzhou, China

An improved Carnegie Ames Stanford Approach (CASA) model based on two kinds of remote sensing (RS) data, Landsat Enhanced Thematic Mapper Plus (ETM +) and Moderate Resolution Imaging Spectro-radiometer (MODIS), and climate variables were applied to estimate the Net Primary Productivity (NPP) of Xuzhou in June of each year from 2001 to 2010. The NPP of the study area decreased as the spatial scale increased. The average NPP of terrestrial vegetation in Xuzhou showed a decreasing trend in recent years, likely due to changes in climate and environment. The study area was divided into four sub-regions, designated as highest, moderately high, moderately low, and lowest in NPP. The area designated as the lowest sub-region in NPP increased with expanding scale, indicating that the NPP distribution varied with different spatial scales. The NPP of different vegetation types was also significantly influenced by scale. In particular, the NPP of urban woodland produced lower estimates because of mixed pixels. Similar trends in NPP were observed with different RS data. In addition, expansion of residential areas and reduction of vegetated areas were the major reasons for NPP change. Land cover changes in urban areas reduced NPP, which could chiefly be attributed to human-induced disturbance.

Developing a management plan for a small urban woodland

SummaryThis article describes an approach to participative planning in the context of a small urban park, including the process of developing the management plan, brief reference to the plan itself and comment on issues that arose during the process. The suburbs of Hughes and Garran in Canberra’s Woden Valley include a small area of mostly planted woodland. In the past decade, this woodland has been partly maintained by a volunteer group which, in collaboration with the land owner, is developing and implementing a management plan to further improve the woodland.

Long-Term Urban Park Ecological Restoration: A Case Study of Prospect Park, Brooklyn, New York

While offering ecological, recreational, and cultural value, urban woodlands are under intense pressure from their many human visitors and require restorative management to continue to provide these functions. Since park construction in the 1860s, the 95.5 hectares of woodlands in Prospect Park (Brooklyn, NY) have experienced the pressures of human use, and were rather degraded by the mid-1980s. Since the early 1990s, Prospect Park’s managers have actively implemented a woodland restoration program that serves as a model for long-term urban restoration. The program has included removing invasive plants, stabilizing eroding soils, planting native vegetation, and redirecting the flow of visitors through the woodlands with improved trails and fences. While initial capital restoration projects were an important component, the true strength of the plan has been the employment of a diverse and dedicated staff—supported by dedicated funding—practicing adaptive management and restoration in Prospect Park’s woodlands. Despite a trend to restore woodlands through capital projects on a limited timeline, managers found that restoration would only be successful with a long-term commitment and continual, incremental restoration work. Given the constant stresses on our urban woodlands, management is needed in perpetuity to maintain a healthy forest in the heart of the city. This article addresses the extent of the managers’ commitment to a restoration program, assesses progress, and attempts to look towards future management needs.

Moth species richness, abundance and diversity in fragmented urban woodlands: implications for conservation and management strategies

Urban expansion threatens global biodiversity through the destruction of natural and semi-natural habitats and increased levels of disturbance. Whilst woodlands in urban areas may reduce the impact of urbanisation on biodiversity, they are often subject to under or over-management and consist of small, fragmented patches which may be isolated. Effective management strategies for urban woodland require an understanding of the ecology and habitat requirements of all relevant taxa. Yet, little is known of how invertebrate, and in particular moth, assemblages utilise urban woodland despite being commonly found within the urban landscape. Here we show that the abundance, species richness, and species diversity of moth assemblages found within urban woodlands are determined by woodland vegetation character, patch configuration and the surrounding landscape. In general, mature broadleaved woodlands supported the highest abundance and diversity of moths. Large compact woodlands with proportionally less edge exposed to the surrounding matrix were associated with higher moth abundance than small complex woodlands. Woodland vegetation characteristics were more important than the surrounding landscape, suggesting that management at a local scale to ensure provision of good quality habitat may be relatively more important for moth populations than improving habitat connectivity across the urban matrix. Our results show that the planting of broadleaved woodlands, retaining mature trees and minimising woodland fragmentation will be beneficial for moth assemblages. © 2014 Springer Science+Business Media Dordrecht.

Assessment of visual landscape quality using IKONOS imagery

The assessment of visual landscape quality is of importance to the management of urban woodlands. Satellite remote sensing may be used for this purpose as a substitute for traditional survey techniques that are both labour-intensive and time-consuming. This study examines the association between the quality of the perceived visual landscape in urban woodlands and texture measures extracted from IKONOS satellite data, which features 4-m spatial resolution and four spectral bands. The study was conducted in the woodlands of Istanbul (the most important element of urban mosaic) lying along both shores of the Bosporus Strait. The visual quality assessment applied in this study is based on the perceptual approach and was performed via a survey of expressed preferences. For this purpose, representative photographs of real scenery were used to elicit observers' preferences. A slide show comprising 33 images was presented to a group of 153 volunteers (all undergraduate students), and they were asked to rate the visual quality of each on a 10-point scale (1 for very low visual quality, 10 for very high). Average visual quality scores were calculated for landscape. Texture measures were acquired using the two methods: pixel-based and object-based. Pixel-based texture measures were extracted from the first principle component (PC1) image. Object-based texture measures were extracted by using the original four bands. The association between image texture measures and perceived visual landscape quality was tested via Pearson's correlation coefficient. The analysis found a strong linear association between image texture measures and visual quality. The highest correlation coefficient was calculated between standard deviation of gray levels (SDGL) (one of the pixel-based texture measures) and visual quality (r = 0.82, P < 0.05). The results showed that perceived visual quality of urban woodland landscapes can be estimated by using texture measures extracted from satellite data in combination with appropriate modelling techniques.

The influence of urban green environments on stress relief measures: A field experiment

This study investigated the psychological (perceived restorativeness, subjective vitality, mood, creativity) and physiological (salivary cortisol concentration) effects of short-term visits to urban nature environments. Seventy-seven participants visited three different types of urban areas; a built-up city centre (as a control environment), an urban park, and urban woodland located in Helsinki, the capital of Finland. Our results show that the large urban park and extensively managed urban woodland had almost the same positive influence, but the overall perceived restorativeness was higher in the woodland after the experiment. The findings suggest that even short-term visits to nature areas have positive effects on perceived stress relief compared to built-up environment. The salivary cortisol level decreased in a similar fashion in all three urban environments during the experiment. The relations between psychological measures and physiological measures, as well as the influence of nature exposure on different groups of people, need to be studied further.

Barriers to the effective planning and management of residential encroachment within urban forest edges: A Southern Ontario, Canada case study

Studies document degradation and loss of publicly owned urban woodland area following adjacent residential development due to residential encroachment. Residential encroachment is the negative impacts of housing land uses within both rural and urban green infrastructure networks. Prevailing planning, design and management approaches in Southern Ontario municipalities in Canada indicate planning and management tools have been developed to remove and impede encroachment impacts; however, many are infrequently implemented. This lack of implementation contributes to a high prevalence and spatial area of encroachment within Southern Ontario municipal woodland edges with adjacent housing. Long interviews were conducted with the planners, landscape architects, woodland managers and bylaw enforcement staff of six Southern Ontario municipalities to determine the barriers to implementation of municipal encroachment tools. Results indicate key barriers to policy implementation that reflect a lack of awareness of, and priority placed on addressing, residential encroachment impacts, and impacts following the point of development in general. Barriers include: (1) insufficient community and municipal access to information regarding residential encroachment and their significance relative to other development impacts; (2) lack of clarity of goals by municipalities and between departments; (3) insufficient municipal leadership and commitment to limiting encroachment; (4) lack of sufficient means within municipal departments to prevent and address encroachment; and (5) ineffectual dynamics of enforcement. Recommendations for overcoming barriers to the development and implementation of effective approaches for addressing encroachment are provided.

Effects of soil pollutants, biogeochemistry and microbiology on the distribution and composition of enchytraeid communities in urban and suburban holm oak stands

Holm oaks form typical urban woodlands in the Mediterranean region. We aimed at characterizing the enchytraeid communities in these environments and searching for possible correlations with soil parameters, including the traffic contamination. Samples of litter and topsoil were collected at different spatial scales and seasons in Naples and Siena cities and in two suburban stands. Only the co-variation between pollution and other soil chemico-physical factors showed significant effects, whereas no direct effect of soil microbiology was detected. Some thermophilous Fridericia and Achaeta tolerate high concentrations of heavy metals and PAHs and their abundance was mainly determined by Ca bioavailability. Central-European mesophilous species increased significantly under more temperate environmental conditions. Different combinations of soil cohesiveness, grain size composition and moisture regime seem to select species of certain body sizes.

Ecological and biological determination of invasion success of non-native plant species in urban woodlands with special regard to short-lived monocarps

Today’s urban green space is exposed to a constant flow of newly introduced exotic plant species, resulting from multiple, intentional and inadvertent introductions. A substantial share of introduced plant species are represented by potential invaders of plant communities, which allows considering that the risk of rapid dispersion by aggressive plant species to be today’s most serious threat to the urban biodiversity. Alien plant species with a short life span (monocarps, therophytes, annuals and biennials) are the most successful invaders across anthropogenically transformed landscapes. These species can have a significant impact on the functioning of previously disturbed ecosystems. At the same time, it is still unclear which mechanisms enable short-lived monocarps to invade under specific conditions of urban forest interiors. Therefore, I have conducted a literature analysis aiming at identifying possible biological and ecological determinants of monocarpic plants’ invasive success in urban woodlands. The analysis was made at three qualitative levels taking into account characteristics of the urban environment, those of different types of urban woodlands as well as traits of non-native monocarpic species. Considering the city level, the main ecological factors are the high level of human-induced disturbance and propagule pressure on the urban-woodland interface sites. The level of invasion as well as invasibility of urban woodlands is mainly determined by the landscape context, whereas the habitat type, species composition and spatial structure play a less important role. In the forest environment, where competition for light and nutrients is the main shaping factor of the phytocoenosis, short-lived alien species must possess a certain level of competitive ability. These findings indicate that this ability may be due to such traits as high fecundity rates, effective dispersal mechanisms, early germination, high rate of growth and the overall big size of plants, presence of autonomous pollination and high shade-tolerance.

Yersel lazer tarama ile tek ağaç özelliklerinin belirlenmesi

In this study, the potential of Terrestrial Laser Scanning (TLS) data obtained from a single point on determination of some individual tree characteristics was assessed. The study was carried out in two beech stands, two Corsican pine stands, and one Douglas fir stand located in an urban woodland in the North England. The targeted tree attributes including diameter at breast height (DBH), tree height, crown base height, and crown width were determined both by the field measurements and from the laser point cloud data. Totally, we measured the DBH in 127 trees in the beech and Corsican pine plots, and the tree height, crown base height, and crown width were determined in 45 trees in only the Corsican pine plots. However, we were not able to measure any tree attributes on the laser point cloud in the sampling plot taken from Douglas fir stand due to high stand density (1393 trees ha-1). The relationships between field-measured and laser-derived tree attributes were determined using simple regression analyses. The obtained determination coefficients (R2) and root mean square errors (RMSE) were; 0,91 and 5.84 cm for DBH; 0,88 and 1,1 m for tree height; 0,83 and 1 m for crown base height; 0,65 and 0,81 m for crown with, respectively. It was concluded that using laser data obtained from a single scan, a) the DBH in definite rate of individuals might be measured in the forest stands with low density; and similarly in some trees, b) the tree height and the other crown characteristics might be determined in conifer stands with a canopy cover less than 70 percent. Keywords: Lidar, Forest inventory, Stand structure

Local habitat characteristics but not landscape urbanization drive pollinator visitation and native plant pollination in forest remnants

Habitat loss from urban development threatens native plant populations in many regions of the world. In addition to direct plant mortality, urban intensification potentially impacts pollinator communities and in turn disrupts the pollination mutualisms that are critical to the viability of native plant populations. We placed standardized flowering plant arrays into woodlands along a gradient of increasing urban land use to simultaneously quantify landscape-scale and local-scale effects on pollinators and on reproduction of two spring ephemeral wildflowers (Claytonia virginica and Polemonium reptans) in woodland fragments in the Mid-Atlantic Region of North America. Greater pollinator abundance and associated diversity significantly reduced the degree of pollen limitation, demonstrating that pollinator populations are critical to successful pollination of these plant populations. However, landscape-scale habitat loss did not reduce pollinator abundance or diversity. Habitat loss at the landscape scale therefore does not appear to drive changes in pollination in this woodland system. Rather, local-scale habitat characteristics were more important, with pollinators being more abundant in brighter woodland patches for one plant species, and in larger patches for the other species. Because we found abundant pollinators and adequate pollination even in isolated, urban woodland fragments, our results are encouraging for the conservation of both plants and pollinators in urban landscapes.

Biotic homogenization at the community scale: disentangling the roles of urbanization and plant invasion

AbstractAimUrbanization as a major global trend profoundly changes biodiversity patterns, and homogenization of urban biota due to expanding exotic species and declining native species is of increasing concern. Previous studies on this topic have mostly taken place at large scales that include high habitat heterogeneity. Here, we aimed at disentangling the effects of urbanization and plant invasion on species composition through the analysis of similarity patterns of urban plant assemblages at the community scale where species interact.LocationBerlin, Germany.MethodsWe analysed how different levels of urbanization, specific components of the urban matrix and the dominance of a native (Betula pendula) versus an exotic tree species (Robinia pseudoacacia) affect alpha and beta diversity of urban woodland understorey vegetation in sixty‐eight 100‐m2 plots.ResultsExotic dominance reduced alpha diversity, but not beta diversity of the total species pool. Comparing beta diversity among different species groups revealed significant but divergent effects of exotic dominance, habitat connectivity and levels of urbanization in native and non‐native species assemblages. In particular, urbanity proved to homogenize the native species pool, whereas the beta diversity of the non‐native species pool showed a more pronounced response to exotic dominance.Main conclusionsOur data provide evidence that both the urban context and the dominance of exotic species can modify homogenization processes at the community level. These novel insights into the mechanisms of biotic homogenization of urban floras may contribute to mitigating the effects of urbanization on biodiversity.

Municipal woodland in Denmark: resources, governance and management

Urban woodlands are the subject of complex decision-making that requires a strategic overview of the resource. This article contributes a national study of municipal woodland in Denmark. Data were collected among all Danish municipalities through a postal survey (with a response rate of 52%). As much as 83% of the woodland units were located within urban settlements or at their fringe, emphasising that municipalities are important urban woodland providers. Municipal woodland resources were typically divided into many separate units of varying size. On average, the responding municipalities owned 12.6 woodland units with an allocated area of 265 ha, resulting in a mean size of 21.5 ha. A general lack of management plans, and a significant drop in recreational facilities provided with decreasing woodland size indicate that the recreational use potential of small woodland units was largely overlooked. Municipal woodland units frequently bordered other woodland or nature areas of different ownership. Thus even small municipal woodlands can play a key role in the development of multifunctional green infrastructures in the urban landscape. Only municipalities with extensive woodland property had issued a woodland policy, and/or certified woodland management. This indicates a need for development of governance and strategic management instruments attractive to municipalities with limited woodland property.

Biotopic distribution, population structure, and some features of small mammal reproduction in Chisinau City

Comparative analysis of species composition, biotopic distribution, population structure, and reproduction of rodents and insectivores in Chisinau City was performed in October–November 2008 (3029 traps days, 715 animals). Sylvaemus sylvaticus appeared to be the most numerous and widely distributed species, the reproductive strategy of which consisted of intense reproduction in the summer. The second most abundant species was Microtus rossiaemeridionalis, which had a different reproductive strategy, with part of its population continuing to reproduce actively in the autumn. Urban woodlands are the most close to natural biotopes by the species composition. The highest number of animals was defined for meadows and gardens. No rodents and insectivores are found on lawns and waste grounds.

Managing urban ancient woodlands: A case study of Bowden Housteads Wood, Sheffield

Managing urban ancient woodland sustainably is problematic and furthermore, there is a lack of detailed, long-term case-study evidence. These issues are discussed with respect to a particular case study site in Sheffield, England. This example is especially informative due to the long timeline of the known site management. It also raises serious issues for future management and the consequences of the processes of urbanisation. Composition, structure and condition of the case-study wood, Bowden Housteads Wood, prior to management in early 1988, are placed in their historical and social contexts. When late twentieth-century management took place, it was the first active intervention on the site for over a century. The implementation of a series of management plans are then described covering the periods 1987–1991, 2000–2005 and 2009–2013. Interpretation of vegetation condition and the monitoring of recovery following intervention demonstrated a remarkable ability of typical ancient woodland flora to reappear. However, there are long-term issues of human encroachment onto the site from nearby housing with the twin impacts of (1) introduction of exotic and potentially invasive species, and (2) destruction of the last pockets of rare woodland indicator plants. The paper emphasises that, in the late twentieth and early twenty-first centuries, managing public amenity woods in heavily populated urban areas is as much about public relations as it is about woodmanship and ecological principles. Furthermore, managing publicly owned amenity woodland is a long-term process and this becomes problematic when public services are being rapidly eroded by national governmental policies. The paper reflects action research and observation with stakeholders over a 30-year period.

The combined effects of conservation policy and co-management alter the understory vegetation of urban woodlands: A case study in the Tama Hills area, Japan

We examined the relative impacts of socioeconomic and biophysical variables on understory vegetation in urban woodlands using the example of satoyama woodland in peri-urban areas of Tokyo, Japan to determine an appropriate institutional framework for enhancing biodiversity and ecosystem services in urban woodlands. Satoyama woodland was historically managed, however, the recent abandonment endangers its biodiversity and ecosystem services. We addressed two main working questions: (1) Which variables (among conservation measures, management actors, and other environmental variables) are the main constraints on the current understory vegetation of urban woodland? (2) How does each management actor behave in the context of different conservation measures and how does this behavior affect the understory vegetation? We employed dwarf bamboo (Pleioblastus chino) as an indicator of the intensity of satoyama woodland management and combined ecological analysis with interviews of municipal officials. We found that the conditions of understory vegetation were mainly affected by differences in the behavior of management actors, as the height of dwarf bamboo was shortest at the woodland managed by community group, followed by municipality and private landowner. This suggests that it will be necessary to consider both biophysical variables and socioeconomic variables in urban ecosystem management. We also found that different management actors had different reasons to conduct or not conduct woodland management. To improve management by these multiple actors, we recommend: developing management plans for conserved areas, providing economic and non-economic support, and developing clear indicators for monitoring the effects of management, with their different behaviors in mind.

Species diversity and nestedness of ant assemblages in an urban environment

Ant assemblages were studied in Warsaw in the context of the effects of urban pressure. Four types of urban greenery were selected: (1) green areas bordering streets, (2) in housing estates, and (3) in parks, and (4) patches of urban woodland. In total, there were 27 species of ants. In terms of the total ant activity density, Lasius niger predominated in all the the lawn biotopes (1-3) and Myrmica rubra in the wooded areas. Ant species diversity was highest in parks and wooded areas and lowest in green areas bor- dering streets. In contrast, activity density was highest in green areas bordering streets and lowest in wooded areas. Some species are found only in a few habitats. Stenamma debile, Lasius brunneus, L. fuliginosus and Temnothorax crassispinus almost exclusively occurred in wooded areas, whereas L. niger was most often found in lawn biotopes. Myrmica rugulosa and Tetramorium caespitum were most abundant in green areas bordering streets, while in parks Lasius flavus, Formica cunicularia and Solenopsis fugax were most abundant. In general, the ant assemblages recorded showed a significantly nested pattern, with biotope type being a significant determinant of nestedness. The assemblages found in green areas in housing estates and bordering streets constituted a subsample of the assemblages in parks and wooded areas. Ant species were non-randomly distributed in this urbanized landscape and the species recorded in the most transformed biotopes constitute subsamples of those inhabiting less transformed biotopes. This finding empha- sizes the importance of wooded areas for the maintenance of biodiversity in urban areas.