Search

Invertebrates comprise the most diversified animal group on Earth. Due to their long evolutionary history and small size, invertebrates occupy a remarkable range of ecological niches, and play an important role as “ecosystem engineers” by structuring networks of mutualistic and antagonistic ecological interactions in almost all terrestrial ecosystems. Urban forests provide critical ecosystem services to humans, and, as in other systems, invertebrates are central to structuring and maintaining the functioning of urban forests. Identifying the role of invertebrates in urban forests can help elucidate their importance to practitioners and the public, not only to preserve biodiversity in urban environments, but also to make the public aware of their functional importance in maintaining healthy greenspaces. In this review, we examine the multiple functional roles that invertebrates play in urban forests that contribute to ecosystem service provisioning, including pollination, predation, herbivory, seed and microorganism dispersal and organic matter decomposition, but also those that lead to disservices, primarily from a public health perspective, e.g., transmission of invertebrate-borne diseases. We then identify a number of ecological filters that structure urban forest invertebrate communities, such as changes in habitat structure, increased landscape imperviousness, microclimatic changes and pollution. We also discuss the complexity of ways that forest invertebrates respond to urbanisation, including acclimation, local extinction and evolution. Finally, we present management recommendations to support and conserve viable and diverse urban forest invertebrate populations into the future.

Background: Publication and co-authorship rates have been increasing over decades. In response, calls are being made to restrict the number of publications included in research evaluations. Yet there is little evidence to guide publication expectations and inform research evaluation for early career researchers (ECRs). Methods: Here we examine the early career publication and co-authorship records between 1970 and 2019 of >140,000 authors of 2.8 million publications, to identify how publication and co-authorship rates have changed over the last 50 years. This examination is conducted in order to develop benchmarks of median publication rates for sensibly evaluating ECR research productivity, and to explore success in meeting these benchmarks with different co-authorship strategies using regression models. Results: Publication rates of multidisciplinary ECRs publishing in Nature, Science and PNAS have increased by 46% over the last 50 years and that publications rates in a set of disciplinary journals have increased by 105%. Co-authorship rates have increased even more, particularly for the multidisciplinary sample which now has 572% more co-authors per publication. Benchmarks based on median publication rates for all authors increased from one publication per year at the start of a career, to four publications per year after 10 years of publishing, and one first-author publication across all years. The probability of meeting these benchmarks increases when authors publish with different co-authors, and first authorship rates decrease for ECRs with many co-authors per publication. Conclusion: This evidence could be used to inform sensible publishing expectations for ECRs and the institutions they work for, and to inform calls to limit the number of publications produced by researchers and those used in research evaluations.

Across all landscape types, environmental managers work with communities to conserve biodiversity. The effectiveness of conservation practice, however, relies on acknowledging differences in preferences and values of nature. Implementing urban conservation is challenging because cities have diverse social, cultural and ecological attributes, meaning there are no simple solutions for the management or co-management of biodiversity. There is little guidance for urban environmental managers on how to 1) engage local urban communities and 2), implement conservation actions specific to cities and their communities. We conducted semi-structured interviews with 27 environmental managers from government and not-for-profit organizations across five Australian capital cities to 1) explore how environmental managers engaged local communities, and 2) understand the factors that enabled or constrained that engagement in conservation. Our aim was to understand the enablers and constraints of engagement with a view to share insights and patterns in the context of the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) conceptual framework’s recognition of the diversity of values associated with nature’s contributions to people (NCP). We found that urban environmental managers facilitated NCP by working to improve people’s relationship with nature. Interviewees reported a range of enablers for community-based biodiversity conservation, including supportive organizational policies and strategies, community support, engaging Indigenous advisory groups, and deploying multi-use, integrative human-nature designs. Constraints and challenges included a lack of top-down commitment, reliance on individuals, and overly simplistic engagement strategies. Based on these findings, we identified opportunities for improved community engagement relevant to organizations responsible for urban environmental management.

Heterogeneity in quantity and quality of resources provided in the urban matrix may mitigate adverse effects of urbanization intensity on the structure of biotic communities. To assess this we quantified the spatial variation in butterfly richness and abundance along an impervious surface gradient using three measures of urban matrix quality: floral resource availability and origin (native vs. exotic plants), tree cover, and the occurrence of remnant habitat patches. Butterfly richness and abundance were surveyed in 100 cells (500 × 500 m), selected using a random-stratified sampling design, across a continuous gradient of imperviousness in Melbourne, Australia. Sampling occurred twice during the butterfly flight season. Occurrence data were analyzed using generalized linear models at local and mesoscales. Despite high sampling completeness, we did not detect 75% of species from the regional species pool in the urban area, suggesting that urbanization has caused a large proportion of the region's butterflies to become absent or extremely rare within Melbourne's metro-area. Those species that do remain are largely very generalist in their choice of larval host plants. Butterfly species richness and abundance declined with increasing impervious surface cover and, contrary to evidence for other taxa, there was no evidence that richness peaked at intermediate levels of urbanization. Declines in abundance appeared to be more noticeable when impervious surface cover exceeded 25%, while richness declined linearly with increasing impervious surface cover. We find evidence that the quality of the urban matrix (floral resources and remnant vegetation) influenced butterfly richness and abundance although the effects were small. Total butterfly abundance responded negatively to exotic floral abundance early in the sampling season and positively to total floral abundance later in the sampling season. Butterfly species richness increased with tree cover. Negative impacts of incre

Green roofs are increasingly promoted for urban biodiversity conservation, but the value of these novel habitats is uncertain. We aimed to test two hypotheses: (i) green roofs can support comparable invertebrate family and order richness, composition and abundances to ground-level habitats and (ii) green roofs planted with native species from local habitats will support a richer invertebrate community at family and order level than other green roofs. We sampled the invertebrate community on green roofs dominated by native grassland or introduced succulent species in Melbourne, Australia, and compared these to the invertebrate community in ground-level sites close by, and sites with similar vegetation types. The only significant differences between the invertebrate communities sampled on green roofs and ground-level habitats were total abundance and fly family richness, which were higher in ground-level habitats. Second hypothesis was not supported as invertebrate communities on green roofs supporting a local vegetation community and those planted with introduced Sedum and other succulents were not detectably different at family level. The per cent cover of green space surrounding each site was consistently important in predicting the richness and abundance of the invertebrate families we focussed on, while roof height, site age and size were influential for some taxa. Our results suggest that invertebrate communities of green roofs in Melbourne are driven largely by their surrounding environment and consequently the effectiveness of green roofs as invertebrate habitat is highly dependent on location and their horizontal and vertical connection to other habitats.

Decisions about urban forests are critical to urban liveability and resilience. This study aimed to evaluate the range of positions held by urban forest managers from local governments in the state of Victoria, Australia, regarding the management and governance challenges that affect their decision-making. This study was based on a Q-method approach, a procedure that allows researchers to evaluate the range of positions that exist about a topic in a structured manner based on the experiences of a wide group of people. We created statements on a wide range of urban forest management and governance challenges and asked urban forest managers to rate their level of agreement with these statements via an online survey. Managers generally agreed about the challenges posed by urban development and climate change for implementing local government policies on urban forest protection and expansion. However, there were divergent views about how effective solutions based on increasing operational capacities, such as increasing budgets and personnel, could address these challenges. For some managers, it was more effective to improve critical governance challenges, such as inter-departmental and inter-municipal coordination, community engagement, and addressing the culture of risk aversion in local governments. Urban forest regional strategies aimed at coordinating management and governance issues across cities should build on existing consensus on development and environmental threats and address critical management and governance issues not solely related to local government operational capacity.

Fallen coarse woody debris (CWD) is critical to forest biodiversity and function. Few studies model factors that influence CWD availability, although such investigations are critically needed to inform sustainable forest management. We assess benchmark levels of CWD in unharvested native forests and those harvested for timber, across a range of forests in north‐east New South Wales, Australia. We found timber‐harvesting was the dominant driver of CWD, with almost double the count (pieces ha−1) and volume (m3 ha−1) of total CWD in selectively harvested than unharvested sites. This pattern was consistent across wet and dry forest types. Harvested sites had greater counts of hollow‐bearing logs, and greater volumes of small and medium‐sized CWD (15–50 cm diameter) than unharvested sites. There was no effect of harvesting on the volume of large CWD (>51 cm diameter). Total volumes of CWD (>15 cm diameter) varied from 114 to 166 m3 ha−1. We found few differences in CWD counts and volumes between forest types, with grassy woodlands and forests containing less CWD than other dry and shrubby forest types, reflecting lower potential input rates. The CWD levels recorded here are similar to those recorded in dry and wet sclerophyll forests elsewhere in Australia and are typical of global estimates for ‘old growth’ forests. Using general linear models we captured up to 57% of the variation in CWD across sites, and found that timber harvesting, topography and the numbers of standing hollow‐bearing and dead trees were significant predictors of CWD. Values for unharvested forest provide a benchmark that could be used to inform retention guidelines for CWD in managed forests in this region. Further assessment of the effect of repeat timber harvesting is needed to fully understand its impact on CWD dynamics, especially if forest residues resulting from timber harvesting are removed from native forests for bioenergy production.

Urbanization is a severe threat to global biodiversity, often leading to taxonomic and functional homogenization. However, current urban ecology research has focused mostly on urban birds and plants, limiting our ability to make generalizations about the drivers of urban biodiversity globally. To address this gap, we conducted a global meta-analysis of 87 studies, including 180 bat species (Chiroptera) from urban areas in Asia, Australia, Europe, North and South America. We aimed to (i) understand the importance of functional traits and phylogeny in driving changes in urban bat assemblages, and (ii) assess the capacity of traits for predicting which types of species are most sensitive to urbanization. Our results indicate that species-specific functional traits explain differences in the intensity of urban habitat use. Urban tolerance mainly occurred within the open and edge space foraging and trawling species as well as in bats with flexible roosting strategies. In addition, across bioregions and independent of phylogeny, urban tolerance correlated with higher aspect ratio, a trait enabling fast flight but less agile manoeuvres during aerial food acquisition. Predictive success varied between bioregions, between 43 and 83%. Our analysis demonstrates that the local extinction of bat species in urban areas is non-random, trait-based and predictable, allowing urban landscape managers to tailor local conservation actions to particular types of species.

Insects are key components of urban ecological networks and are greatly impacted by anthropogenic activities. Yet, few studies have examined how insect functional groups respond to changes to urban vegetation associated with different management actions. We investigated the response of herbivorous and predatory heteropteran bugs to differences in vegetation structure and diversity in golf courses, gardens and parks. We assessed how the species richness of these groups varied amongst green space types, and the effect of vegetation volume and plant diversity on trophic- and species-specific occupancy. We found that golf courses sustain higher species richness of herbivores and predators than parks and gardens. At the trophic- and species-specific levels, herbivores and predators show strong positive responses to vegetation volume. The effect of plant diversity, however, is distinctly species-specific, with species showing both positive and negative responses. Our findings further suggest that high occupancy of bugs is obtained in green spaces with specific combinations of vegetation structure and diversity. The challenge for managers is to boost green space conservation value through actions promoting synergistic combinations of vegetation structure and diversity. Tackling this conservation challenge could provide enormous benefits for other elements of urban ecological networks and people that live in cities.

Networks of urban green space can provide critical resources for wild bees, however it is unclear which attributes of green spaces provide these resources, or how their management can be improved to benefit a diversity of bee species. We examined bee communities in three dominant urban green space habitats: (1) golf courses (2) public parks and (3) front gardens and streetscapes in residential neighbourhoods in Melbourne, Australia and assessed which local and landscape attributes influenced bee communities. There was a greater abundance and richness of bee species in public parks compared to golf courses and residential neighbourhoods, where the latter habitat was dominated by European Honeybees (Apis mellifera). The occurrence of A. mellifera was positively associated with increases in flowering and native plants. Ground-nesting Homalictus species occurred more frequently in older golf courses and public parks surrounded by low impervious surface cover, and with a low diversity of flowering plants. Cavity nesting, floral specialists within the Colletidae family occurred more often in green space habitats with greater native vegetation, and occurred infrequently in residential neighbourhoods. The lack of appropriate nesting habitat and dominance of exotic flowering plants in residential neighbourhoods appeared to positively impact upon the generalist A. mellifera, but negatively affected cavity and ground nesting floral specialist bee species (e.g. Halictidae and Colletidae). Our results highlight the need to include urban areas in pollinator conservation initiatives, as providing resources critical to diverse bee communities can assist in maintaining these key pollinators in urban landscapes.

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups - including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems - http://www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.

Urban landscapes are often located in biologically diverse, productive regions. As such, urbanization may have dramatic consequences for this diversity, largely due to changes in the structure and function of urban communities. We examined the influence of landscape productivity (indexed by geology), housing density and vegetation clearing on the spatial distribution of nocturnal insect biomass and the foraging activity of insectivorous bats in the urban landscape of Sydney, Australia. Nocturnal insect biomass (g) and bat foraging activity were sampled from 113 sites representing backyard, open space, bushland and riparian landscape elements, across urban, suburban and vegetated landscapes within 60 km of Sydney's Central Business District. We found that insect biomass was at least an order of magnitude greater within suburban landscapes in bushland and backyard elements located on the most fertile shale influenced geologies (both p<0.001) compared to nutrient poor sandstone landscapes. Similarly, the feeding activity of bats was greatest in bushland, and riparian elements within suburbs on fertile geologies (p = 0.039). Regression tree analysis indicated that the same three variables explained the major proportion of the variation in insect biomass and bat foraging activity. These were ambient temperature (positive), housing density (negative) and the percent of fertile shale geologies (positive) in the landscape; however variation in insect biomass did not directly explain bat foraging activity. We suggest that prey may be unavailable to bats in highly urbanized areas if these areas are avoided by many species, suggesting that reduced feeding activity may reflect under-use of urban habitats by bats. Restoration activities to improve ecological function and maintain the activity of a diversity of bat species should focus on maintaining and restoring bushland and riparian habitat, particularly in areas with fertile geology as these were key bat foraging habitats.