Biodiversity In Urban Ecosystems Research Articles

Green Roofs Affect the Floral Abundance and Phenology of Four Flowering Plant Species in the Western United States

This study investigates the potential for green roofs to support pollinator diversity and abundance in urban ecosystems through the altered floral phenology and floral abundance of plants. Floral phenology and the floral abundance of green roof plants are compared to plants grown at grade on the Front Range in Fort Collins, Colorado, and how these changes may affect pollinator biodiversity in urban ecosystems. An independent block design is employed, within one green roof and one ground-level garden, approximately 120 m apart, with replicate plants of 4 species in each garden. Pollinator observations were made weekly during the bloom period for each species. Blue vane traps were used to passively measure pollinator diversity along a transect between the green roof sites and the sites at grade. The total number of flowers per plant is variable between site types, depending on the plant species. However, all species of plants tested bloomed earlier when grown on the green roof than when grown at grade. Pollinator abundance and diversity were low at both site locations. Green roofs may provide foraging opportunities earlier in the season in temperate regions, which can extend the duration of floral foraging opportunities when supported by green infrastructure at grade.

Drivers of arthropod biodiversity in an urban ecosystem

Our world is becoming increasingly urbanized with a growing human population concentrated around cities. The expansion of urban areas has important consequences for biodiversity, yet the abiotic drivers of biodiversity in urban ecosystems have not been well characterized for the most diverse group of animals on the planet, arthropods. Given their great diversity, comparatively small home ranges, and ability to disperse, arthropods make an excellent model for studying which factors can most accurately predict urban biodiversity. We assessed the effects of (i) topography (distance to natural areas and to ocean) (ii) abiotic factors (mean annual temperature and diurnal range), and (iii) anthropogenic drivers (land value and amount of impervious surface) on the occurrence of six arthropod groups represented in Malaise trap collections run by the BioSCAN project across the Greater Los Angeles Area. We found striking heterogeneity in responses to all factors both within and between taxonomic groups. Diurnal temperature range had a consistently negative effect on occupancy but this effect was only significant in Phoridae. Anthropogenic drivers had mixed though mostly insignificant effects, as some groups and species were most diverse in highly urbanized areas, while other groups showed suppressed diversity. Only Phoridae was significantly affected by land value, where most species were more likely to occur in areas with lower land value. Los Angeles can support high regional arthropod diversity, but spatial community composition is highly dependent on the taxonomic group.

Gulls living in cities as overlooked seed dispersers within and outside urban environments

The yellow-legged gull is an opportunistic and generalist bird that has colonised urban areas, where it has found very favourable trophic resources but also causes disturbance to humans and damage to infrastructure. Here, we investigated the potential role that gulls play in the dispersal of plants in Barcelona, a highly populated city of north-eastern Spain. We analysed the stomach contents of 145 chicks collected in urban nests and reported the presence of seeds of 27 plant taxa. We then developed a plant dispersal model based on the movements of 20 GPS-tracked yellow-legged gulls breeding in the city of Barcelona. We estimated seed dispersal distances, seed shadows and percentage of seeds reaching habitats suitable for seeds regurgitated in pellets and those excreted in faeces. Seven of the 27 plant taxa found in the stomachs were alien taxa to Spain. Average dispersal distances of plant seeds by gulls were around 700 m, but maximum dispersal distances reached up to 35 km. Dispersal distances and seed spatial patterns did not differ between faeces and pellet models, as most strongly depended on gull movements. About 95% of the seeds were dispersed within urban environments and between 20 and 30% reached suitable habitats for seed deposition (urban woodlands, green urban parks and urban grasslands). Urban gulls frequently dispersed seeds (including alien species) within urban habitats, both via direct consumption or via secondary dispersal after consuming granivorous birds that had ingested the seeds, such as pigeons or parakeets. Urban planning for Barcelona is based on native plant species, and thus, special attention should be paid to alien plants dispersed by birds, which could pose a risk to native biodiversity in urban ecosystems.

Raptor breeding sites indicate high plant biodiversity in urban ecosystems

Preserving biodiversity in urban ecosystems has become an urgent conservation priority, given the rapid upsurge in global urbanization. As woody plants play essential ecological roles and provide psychological benefits to human city dwellers, their preservation is of particular interest to conservation scientists. However, considering that extensive censuses of woody plants are resource-intensive, a key accomplishment is to find reliable conservation proxies that can be quickly used to locate biologically diverse areas. Here, we test the idea that sites occupied by apex predators can indicate high overall biodiversity, including high diversity of woody plants. To this end, we surveyed woody plant species within 500 m of Northern Goshawk (Accipiter gentilis) breeding sites in urban ecosystems of Japan and compared them with non-breeding control sites without goshawks. We found that goshawks successfully identified and signposted high levels of richness, abundance, and diversity of woody plants. Our findings show that sites occupied by top predatory species could be exploited as conservation proxies for high plant diversity. Due to their exigent ecological requirements, we would expect apex predators to be tied to high biodiversity levels in many other urban ecosystems worldwide.

Positive relationships among aboveground biomass, tree species diversity, and urban greening management in tropical coastal city of Haikou.

Within urban green spaces, tree species diversity is believed to correlate with aboveground biomass, though there is some disagreement within the literature on the strength and directionality of the relationship. Therefore, we assessed the relationship between the biodiversity of woody species and the aboveground biomass of woody plant species in the tropical, coastal city of Haikou in southern China. To accomplish this, we obtained comprehensive tree and site data through field sampling of 190 urban functional units (UFUs, or work units) corresponding to six types of land uses governmental‐institutional, industrial‐commercial, park‐recreational, residential, transport infrastructure, and undeveloped area. Based on our field data, we investigated the relationship between tree species diversity and aboveground biomass using multiple regression, which revealed significant relationships across all five types of land uses. Aboveground biomass in green spaces was also correlated with anthropogenic factors, especially time since urban development, or site age, annual maintenance frequency by human caretakers, and human population density. Among these factors, maintenance is the strongest predictor of aboveground biomass in urban green space. Therefore, this study highlights the critical role of maintenance of urban green space in promoting both aboveground biomass and woody biodiversity in urban ecosystems and, consequently, on urban ecosystem services. Our findings contribute to a deeper understanding of the ecosystem services provided by communities of woody plant species in urban areas.

Invasion theory as a management tool for increasing native biodiversity in urban ecosystems

Abstract Human activity has altered ecosystems in some places to a point where traditional restoration, ecosystem management and conservation interventions might not be feasible. This is especially true in densely populated urban areas if ongoing stressors are not ameliorated. As a result, different management options are needed for increasing native biodiversity and ecosystem function in novel urban ecosystems. One strategy for increasing biodiversity in urban ecosystems is to employ invasion biology theory to augment the establishment and proliferation of desirable native species. Invasion hypotheses, including fluctuating resources, enemy release, novel weapons, invasional meltdown (facilitation) and propagule pressure, all provide insights into the mechanisms that increase the establishment and spread of populations. These hypotheses point to specific interventions that can be used in urban restoration and management. Synthesis and applications. Viewing invasion mechanisms as a way to increase native biodiversity in novel urban ecosystems provides a useful reframing for assessing possible applications and management interventions for the most difficult‐to‐restore landscapes. We argue that conservation managers can use and test invasion hypotheses to inform biodiversity management practices in novel landscapes.

Biodiversity indices for the Futog park (Novi Sad, Serbia)

Biodiversity and biodiversity preservation are some of the most important topics in ecology. Protecting biodiversity in urban ecosystems is especially challenging. Urban parks are a valuable part of green infrastructure in cities, as they contribute to preserving natural habitats for many species. Biodiversity can be quantified by calculating different diversity indices, and in this paper, we have calculated alpha indices (Shannon, Simpson, Fisher, Berger-Parker and Margalef index) and beta indices (Sorensen index, Jaccard distance and Bray-Curtis index) for the Futog park in Novi Sad, Serbia, within two periods, 2005 and 2020. The goal of the paper is to analyze the current values of biodiversity indices in the park and compare them with the ones from 15 years ago. In addition to the analysis of biodiversity indices values, the paper provides the comparison of taxonomic structure of flora, and the abundance of native, endemic and invasive species in the park, in 2005 and 2020. The results show that the values of biodiversity indices have decreased in the indicated period of time, and one of the main causes can be related to the spread of invasive species within the park. For calculation purposes, we have used the R program and the R package ?vegan?.

Annotated list of beetles (Insecta, Coleoptera) in an urban area of the Eastern Andes of Colombia

We present the first list of beetle species from an urban area in the northeast Andes of Colombia, based on a review of specimens deposited in the insect collection of the Museo de Historia Natural “Luis Gonzalo Andrade” of the Universidad Pedagógica y Tecnológica de Colombia and from sporadic collections from various points around the city of Tunja, Boyacá. We recorded 34 species, 30 genera, 17 subfamilies, and 12 families of beetles. Of these, 10 new records for the department of Boyacá and two new species records for Colombia are reported. In addition, we recorded the type of urban habitat for the individuals of 24 species collected: 11 species in gray areas (roads, sidewalks, houses, buildings) and eight in green areas (parks, pastures, plantations). Our results form a baseline for further studies on biodiversity in urban ecosystems in the Eastern Andes of Colombia.

The state of the world’s urban ecosystems: What can we learn from trees, fungi, and bees?

Social Impact StatementPositive interactions between people and nature inspire behaviours that are in harmony with biodiversity conservation and also afford physical and mental health benefits. Since most people live in towns and cities, urban greenspaces are key points of influence for conservation, but also provide diverse ecosystem services. City trees are a foundation for biodiversity in urban ecosystems, and their belowground interactions with mycorrhizal fungi and aboveground interactions with pollinators must be central to urban ecosystem planning. Messaging about biodiversity must be clearer to avoid unintended negative outcomes from conservation actions such as low diversity tree planting and unsustainable levels of urban beekeepingSummaryTrees are a foundation for biodiversity in urban ecosystems and therefore must be able to withstand global change and biological challenges over decades and even centuries to prevent urban ecosystems from deteriorating. Tree quality and diversity should be prioritized over simply numbers to optimize resilience to these challenges. Successful establishment and renewal of trees in cities must also consider belowground (e.g., mycorrhizas) and aboveground (e.g., pollinators) interactions to ensure urban ecosystem longevity, biodiversity conservation and continued provision of the full range of ecosystem services provided by trees. Positive interactions with nature inspire people to live more sustainable lifestyles that are consistent with stopping biodiversity loss and to participate in conservation actions such as tree‐planting and supporting pollinators. Interacting with nature simultaneously provides mental and physical health benefits to people. Since most people live in cities, here we argue that urban ecosystems provide important opportunities for increasing engagement with nature and educating people about biodiversity conservation. While advocacy on biodiversity must communicate in language that is relevant to a diverse audience, over‐simplified messaging, may result in unintended negative outcomes. For example, tree planting actions typically focus on numbers rather than diversity while the call to save bees has inspired unsustainable proliferation of urban beekeeping that may damage wild bee conservation through increased competition for limited forage in cities and disease spread. Ultimately multiple ecosystem services must be considered (and measured) to optimize their delivery in urban ecosystems and messaging to promote the value of nature in cities must be made widely available and more clearly defined.

Ecosystem functioning in urban grasslands: The role of biodiversity, plant invasions and urbanization.

Urbanization is driving the transformation of natural and rural ecosystems worldwide by affecting both the abiotic environment and the biota. This raises the question whether urban ecosystems are able to provide services in a comparable way to their non-urban counterparts. In urban grasslands, the effects of urbanization-driven ecological novelty and the role of plant diversity in modulating ecosystem functioning have received little attention. In this study, we assessed the influence of biodiversity, abiotic and biotic novelty on ecosystem functioning based on in situ measurements in non-manipulated grasslands along an urbanization gradient in Berlin (Germany). We focused on plant aboveground biomass (AGB), intrinsic water-use efficiency (iWUE) and 15N enrichment factor (Δδ15N) as proxies for biomass production, water and N cycling, respectively, within grassland communities, and tested how they change with plant biogeographic status (native vs alien), functional group and species identity. Approximately one third of the forb species were alien to Berlin and they were responsible for 13.1% of community AGB. Community AGB was positively correlated with plant-species richness. In contrast, iWUE and Δδ15N were mostly determined by light availability (depicted by sky view factor) and urban parameters like the percentage of impervious surface or human population density. We found that abiotic novelty potentially favors aliens in Berlin, mainly by enhancing their dispersal and fitness under drought. Mainly urban parameters indicating abiotic novelty were significantly correlated to both alien and native Δδ15N, but to AGB and iWUE of alien plants only, pointing to a stronger impact of abiotic novelty on N cycling compared to C and water cycling. At the species level, sky view factor appeared to be the prevailing driver of photosynthetic performance and resource-use efficiency. Although we identified a significant impact of abiotic novelty on AGB, iWUE and Δδ15N at different levels, the relationship between species richness and community AGB found in the urban grasslands studied in Berlin was comparable to that described in non-urban experimental grasslands in Europe. Hence, our results indicate that conserving and enhancing biodiversity in urban ecosystems is essential to preserve ecosystem services related to AGB production. For ensuring the provision of ecosystem services associated to water and N use, however, changes in urban abiotic parameters seem necessary.

Functional diversity of different vegetation types does not respond homogeneously to change over time after conservation translocation from a rural landscape to an urbanized one

The anthropogenic impact on natural environments and the loss of species diversity along with changes in functional diversity call for effective steps to ensure habitat conservation. The functional diversity in particular has suffered in recent decades due to investment and land use changes. The translocation of whole turfs of certain vegetation plots prior to being destroyed is one possible solution for maintaining habitat functional diversity. In the presented paper, we analyse the functional changes in adaptive, regeneration and urbanity plant traits for meadow, heath and fen that were translocated from a rural site to a post-industrial site in a city. After five years of monitoring, we checked the changes in the functional diversity (FD) and community weighted means with the adoption of nine traits and Rao’s quadratic entropy for calculating the FD and the relative treatment effect (RTE) to evaluate the influence of time. We found that the overall FD of that trait set was not significantly changed. The FD of the seed dispersal type significantly increased. The means of autochoric, anemochoric and hemerochoric species decreased, and nautochoric and zoochoric species increased significantly, with respect to the frequency and abundance. The flowering season was shorter for meadows and heaths with earlier start and termination. The most important factors of the FD changes are probably linked to the microclimate of the urbanized area and the cessation of grazing. Our study demonstrated that translocation of vegetation plots from rural to urbanized environments can be a fairly effective measure in landscape shaping and in promoting biodiversity in urban ecosystems.

Urban biodiversity in China: Who are winners? Who are losers?

Rapid urbanization in the last three decades has impacted biogeographic patterns of wildlife in China profoundly. Large areas of natural habitats have been converted into concentrated industrial and residential areas [1]. Remaining habitats in vicinities of cities are often fragmented and degraded [2]. Besides land use/land cover changes, anthropogenic disturbances such as the introduction of exotic species further add pressure on local biodiversity [3]. How does wildlife respond to these impacts? Who will win and who will lose in this urbanization process in China? Answers to these questions will help conservation agencies to manage the impacts of urbanization on biodiversity more effectively. A general finding from urban biodiversity studies is that urbanization favors exotic species over native species because of the environmental filtering effect and anthropogenic influences [3]. The temporal change of species composition of birds in Beijing serves as a good example. By comparing the species composition of birds in Beijing recorded during 1954–1978 [4, 5] to those recorded during 2003–2013 (Chinese Bird Reports, http://www.chinabirdnet. org/report.html; eBird, http://www.ebird.org/), one can find that the proportion of species whose distribution ranges are outside of Beijing increased significantly, up from 22 % of the 172 observed species to 46 % of the 409 observed species. Three species whose distribution ranges encompass Beijing could not be observed in the later time (Names of species listed in supplementary Table S1). The gain of exotic species and loss of native species cause biotic homogenization, which is considered one of the most prominent forms of biotic impoverishment worldwide [6]. The diversity pattern of urban woody plants in China bears the evidence of this trend. Assemblages of urban woody plants from 35 Chinese cities had lower dissimilarities of species composition between urban areas than these of woody plants in natural areas (Fig. 1a, b, paired t test, P 0.001), which indicated that urbanization had a homogenization effect. This effect was significant and detectable as social factors explained 11 % of variation in the composition dissimilarity (Fig. 1c). Species from families like Prunus, Populus, and Magnolia have contributed to the homogenization of urban woody plants, which may be due to their wide use in landscaping. That rapid urbanization in China has caused negative impacts on urban biodiversity is supported bymore andmore evidences. The question is: ‘‘Why bother?’’ China has the largest urban population in the world—670 million and an additional 100million by 2020 is expected [7].Many of them experience ‘‘nature’’ primarily in urban areas. Preservation of urban biodiversity will increase their awareness to the importance of biodiversity conservation in nature [8]. Values of urban biodiversity are not restrict to psychological and educational benefits. Urban biodiversity is the foundation of a healthy urban ecosystem. Preserving biodiversity in urban ecosystems can sustain the supply of much-needed Electronic supplementary material The online version of this article (doi:10.1007/s11434-016-1187-7) contains supplementary material, which is available to authorized users.

Identification of interconnections between landscape pattern and urban dynamics—Case study Bratislava, Slovakia

The change of land use in urban and suburban areas is an on-going process. The aim of this paper is to study and statistically model landscape patterns changes in the Bratislava region (Slovakia) between 2002 and 2011. In the study, we perform the classic landscape-ecological method of land use mapping, and several spatial analytical tools provided by the GIS environment with statistical modeling using obtained spatial data. In order to explicitly study the determinants of landscape patterns changes between 2002 and 2011, firstly an exploratory principal component analysis (PCA) is performed with variables obtained from GIS modeling. Secondly, the results from PCA are used in the logistic regression model. The landscape patterns changes were defined as transition areas in which the change of function has been performed in the study time period. The proposed regression model estimates the threshold probability of the landscape patterns’ changes of transition areas under the effect of the adjacent areas. In order to accurately capture land use changes, high resolution aerial photographs of the Bratislava area including the city and surrounding villages from 2002 to 2011 were analyzed. The spatial buffers mapping of the transition areas in the GIS environment was based on data from ortophotos in the precise scale of 1:2000. Key methodology findings are regularities about the process of urban dynamics, focused on the change of urban boundaries in the urban system contact area. Various behavior rules have been defined such as embedded distance, spatial pattern and transition probabilities, which are essential in the proposed logistic regression model. In order to pragmatically incorporate the regression model as a software model tool, it needs to generate effective urban simulations consistent with GIS data inputs, outputs and related functionality. This enables utilizing the software model, which might be incorporated as a plugin in the GIS environment. Both GIS and statistical regression modeling might be used as predictive tools in an urban policy decision making, with a better understanding of discrete non-linear urban dynamics and to ensure the sustainable use of land and the protection of biodiversity in urban ecosystems.

Aquatic Insect Assemblages of Man-Made Permanent Ponds, Buenos Aires City, Argentina

Freshwater habitats are important elements within urban green space and they are endangered by various types of human activity. With the aim to increase the knowledge about species biodiversity in urban ecosystems, we characterised the assemblages of aquatic insects in four permanent man-made ponds in Buenos Aires city (Argentina) during a 1-year period. We recorded 32 species with Sigara spp. (Hemiptera) as the most abundant. The removal of aquatic vegetation from the studied ponds may have affected both the establishment and permanence of the insect community. Swimmers were the dominant group in the studied sites, followed by burrowers and sprawlers, and only a few strictly climbers were collected. Therefore, all sampled ponds were dominated by collectors (principally gatherers), secondarily by predators and only few shredders were detected, which was much affected by the removal of macrophytes. Non-parametric abundance indexes estimated a number of species very close to the observed number in each site. Conversely, the incidence indexes estimated more species because there were many more taxa present only in one sample than those represented by few individual in a sample. Our data provides some insights on the community of man-made ponds that can improve the management of these aquatic urban habitats. Considering that macrophytes affect animal assemblages due to their role as physical structures that increase the complexity or heterogeneity of habitats, they should not be removed by authorities in order to promote biodiversity.

Residential Areas Support Overwintering Possibilities of Most Bird Species

Spatial variation in wintering bird communities in different types of urban residential areas is poorly understood. The objective of tills study was to find out which bird species from the regional species pool are able to inhabit residential areas, whether bird communities in different types of residential area differ from one another, and what are the factors affecting birds. We conducted our study in five apartment-building areas, five family-house areas, and five villages in northern Finland by using the single-visit study plot method during five winters, i.e. 1998/1999–2003/2004. Oldgrowth-forest-specialist species, in particular, avoided residential areas, whereas the other species appeared to benefit from residential development. The species richness, the total number of individuals, and the abundance of most of the species were higher in the family-house areas and in villages than in apartment-building areas. The proportion of individuals belonging to resident species was higher in the apartment-building areas than in the other habitats, whereas the proportion of individuals belonging to feeding-table species was higher in the villages than in the other habitats. The species richness and the total number of individuals increased with the increasing number of feeding tables and decreased with increasingly larger proportions of apartment buildings within the study plot. Parus montanus, P. major, P. caeruleus, Passer domesticus, and Carduelis flammea benefitted from feeding tables. Our study demonstrated that carefully planned winter feeding programmes can enhance the wintering possibilities for birds, and thus promote the biodiversity in urban ecosystems at northern latitudes.

Biodiversity in urban ecosystems: Plants and macromycetes as indicators for conservation planning in the city of Coimbra (Portugal)

Urban landscapes support a high and rich diversity often occurring as unusual or unique communities. Urban green areas are a vital part of the urban landscape, providing contact with wildlife and environmental services with additional socio-ecological benefits to the overall quality of life. The composition and diversity of vascular plants and macromycetes were assessed in an urban green area of the city of Coimbra (central Portugal) comprising three landscape types (Oak-, Eucalyptus-, and Olive-stands), with historical periurban agriculture and forest uses. We recorded 287 taxa of plants, including three taxa with important ecological value (Quercus suber, Quercus faginea subsp. broteroi and Ruscus aculeatus) and 96 taxa of macromycetes. The pattern of land use resulted in the establishment of different plant and soil fungal communities’ composition and diversity among these landscapes. The plant richness and diversity indices revealed similar trends within the landscape types, with the highest values found in the Olive-stands due to the presence of herbaceous that decreased with tree cover density. Richness and diversity of macromycetes were higher in Oak-stands especially the symbiotic ectomycorrhizal (ECM) fungal communities. Although not significant, higher saprobic fungi richness and diversity values were found in the Eucalyptus-stands. Given the undoubted ecological complexity of urban green areas and the value of these ecosystems for society in terms of goods and services, it is imperative to select bioindicators that are readily accessible and reliable to design balanced urban ecosystems by linking wildlife and biological parameters to human well-being.

Birds of different biogeographic origins respond in contrasting ways to urbanization

Impacts of urbanization on ecological systems are expected to increase during the 21st century, and identifying which species may not survive under urban constraints is of practical importance to conservation biology. I study whether a species’ biogeographic origin might be a useful predictor of vulnerability to urban pressures, and if this depends on the geographic scale of the study. By means of multivariate ordination analyses and computer intensive, Monte Carlo simulation techniques, I study the patterns of zoogeographical affinity (a proxy for biogeographic origin) of passerine birds living in 14 non-urban (NU) and 11 urban (U) sites throughout Mexico, a biodiversity rich and urbanizing country between the Nearctic and Neotropical Regions; at a regional scale, I also study differences between NU and U sites in the state of Puebla, in the ‘Temperate Sierras’ ecoregion. Differences in zoogeographical affinities between NU and U sites were statistically significant, and were mainly caused by changes in the number of neotropical and nearctic species. In terms of the ‘equivalent number of zoogeographical classes’, a useful measure of zoogeographical diversity, bird assemblages in urban settings were less diverse than those simulated by random drawings from the corresponding species pools. In fact, urbanization seems to be provoking the selective removal of neotropical and endemic species from urban assemblages, whereas at the same time retaining more-than-expected nearctic (temperate) species; birds with nearctic affinities could be successful candidates to ‘urban exploiters’ in the study case. At a landscape scale, results suggest that urbanization is creating holes in the geographic range of both neotropical passerines and birds endemic to Mexico, which are selectively removed by the urban filter, and can be identified as those more heavily threatened by urbanization if proactive strategies to conserve biodiversity in urban ecosystems are not implemented. Among other reasons for the observed patterns, the tropical niche conservatism is invoked as an explanation.

Arthropods of a semi-natural grassland in an urban environment: the John F. Kennedy International Airport, New York

Semi-natural grassland habitat fragments, such as those found on airports, might be important for arthropod conservation and biodiversity in urban ecosystems. The objectives of this study were to: (1) describe the arthropod communities present within the grasslands on the John F. Kennedy International Airport and (2) assess spatial and temporal variation in those arthropod communities. We collected arthropods using a vacuum sampler during 2003 and using sweep-net collection methods during 2003 and 2004. During 2003, a total of 1,467 arthropods, representing 17 orders and 68 families were found in vacuum samples. A total of 3,784 arthropods, representing 12 orders and 94 families were collected in sweep-net samples during 2003. In 2004, a total of 3,281 arthropods, representing 12 orders and 85 families were collected in sweep-net samples. Hemiptera, Orthoptera, and Diptera were the most abundant taxa, accounting for 47, 18, and 14% of all arthropods captured, respectively. We found evidence of spatial and temporal variation in arthropod abundance, in particular as noted by fluctuations in Orthoptera: Acrididae and Hemiptera: Auchenorrhyncha. Hemipteran family diversity was also influenced by habitat type. Grassland habitats on airfields, although influenced by anthropogenic factors (e.g., mowing), have the potential to provide abundant and diverse arthropod communities and might serve as a refugium for such species within urban ecosystems.

Harbour swimming nets: a novel habitat for seahorses

1. Artificial structures are becoming increasingly important in conserving biodiversity in urban ecosystems, by providing habitat for endangered or rare species. Their role in providing habitat for such species has, however, been largely unexplored. 2. In Sydney Harbour, Australia, seahorses were observed among the netting used to keep sharks out of swimming enclosures. Over a 2-year period, the relative densities of two species of seahorses observed on netting was measured at swimming enclosures with permanent netting and at swimming areas that were only enclosed with netting during the summer months. 3. The rate of colonization by seahorses to new netting was also examined over a period of 10 months. 4. Numbers of seahorses on permanent swimming enclosures were 10 to 100 times greater than numbers present on swimming enclosures that were only set up during the summer months. 5. This large difference may have been attributed to the slow rate of colonization of seahorses to new habitat. Seahorses were not observed at experimental nets that were deployed in two areas in the harbour until at least 4 months after the netting was deployed. 6. Swimming pool nets are a habitat for species of seahorses in Sydney Harbour and, consequently, the removal or disturbance of swimming nets may impact the survival of these fish. Management of these artificial habitats may therefore best be focused on providing a permanent habitat that may help to compensate for the loss of netting during winter months. Copyright © 2007 John Wiley & Sons, Ltd.

Biodiversity concepts and urban ecosystems

The association of biodiversity and urban ecosystems has usually concerned the impact of urbanization on biodiversity. However, biodiversity concepts can easily be applied to the urban ecosystem itself. As more and more people live in cities, restoration, preservation and enhancement of biodiversity in urban areas become important. Concepts related to biodiversity management such as scale, hierarchy, species identity, species values, fragmentation, global approaches can be used to manage urban biodiversity. Application of these concepts in such artificial ecosystems may yield important insights for the management of natural ecosystems. Birds are highly visible and quite sensitive to changes in habitat structure and composition. Bird species richness in urban ecosystems is influenced both by local and landscape characteristics and a multi-scale approach is essential to its proper management. People–wildlife conflicts are an integral component of wildlife management in urban ecosystems and must be addressed. Enhancement of biodiversity in urban ecosystems can have a positive impact on the quality of life and education of urban dwellers and thus facilitate the preservation of biodiversity in natural ecosystems.