The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.

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Urbanization is one of the major anthropogenic processes contributing to local habitat loss and extirpation of numerous species, including wild bees, the most widespread pollinators. Little is known about the mechanisms through which urbanization impacts wild bee communities, or the types of urban green spaces that best promote their conservation in cities. The main objective of this study was to describe and compare wild bee community diversity, structure, and dynamics in two Canadian cities, Montreal and Quebec City. A second objective was to compare functional trait diversity among three habitat types (cemeteries, community gardens and urban parks) within each city. Bees were collected using pan traps and netting on the same 46 sites, multiple times, over the active season in 2012 and 2013. A total of 32,237 specimens were identified, representing 200 species and 6 families, including two new continental records, Hylaeus communis Nylander (1852) and Anthidium florentinum (Fabricius, 1775). Despite high community evenness, we found significant abundance of diverse species, including exotic ones. Spatio-temporal analysis showed higher stability in the most urbanized city (Montreal) but low nestedness of species assemblages among the three urban habitats in both cities. Our study demonstrates that cities are home to diverse communities of wild bees, but in turn affect bee community structure and dynamics. We also found that community gardens harbour high levels of functional trait diversity. Urban agriculture therefore contributes substantially to the provision of functionally diverse bee communities and possibly to urban pollination services.

To test whether spider succession following harvest differed from succession following wildfire, spiders were collected by pitfall trapping and sweep netting over two years in aspen‐dominated boreal forests. Over 8400 individuals from 127 species of spiders were identified from 12 stands representing three age‐classes (stand origin in 1995, 1982, and 1968) and two disturbance types (wildfire and harvesting). The diversity of spider assemblages tended to be higher in fire‐origin stands than in harvest‐origin stands; the youngest fire‐origin stands also supported more even distributions of spider species. Spider assemblages responded quickly to wildfire and harvesting as open habitat specialists colonized stands within one year after disturbance. Many web‐building species common to older forests either survived harvesting, or re‐colonized harvest‐origin stands more rapidly than they re‐colonized fire‐origin stands. Cluster analyses and DCA ordination show faunal convergence by ca 30 years after wildfire and harvesting; trajectories in re‐colonization, however, differed by disturbance type as the succession of spider assemblages from fire‐origin stands lagged behind spider succession in harvest‐origin stands. Comparison with cluster analyses using vegetation data and abiotic site conditions suggests spider assemblages recover from harvesting and fire more rapidly than do a variety of other site characteristics. Several spider species (e.g. Gnaphosa borea Kulezyński, Pirata bryantae Kurata, Arctosa alpigena (Doleschall)) appear dependent on some of the conditions associated with wildfires as they were absent or rarely collected in harvest‐origin stands.

2000. Succession of boreal forest spider assemblages following wildfire and harvesting. -Ecography 23: 424-436.To test whether spider succession following harvest differed from succession following wildfire, spiders were collected by pitfall trapping and sweep netting over two years in aspen-dominated boreal forests. Over 8400 individuals from 127 species of spiders were identified from 12 stands representing three age-classes (stand origin in 1995, 1982, and 1968) and two disturbance types (wildfire and harvesting). The diversity of spider assemblages tended to be higher in fire-origin stands than in harvest-origin stands; the youngest fire-origin stands also supported more even distributions of spider species. Spider assemblages responded quickly to wildfire and harvesting as open habitat specialists colonized stands within one year after disturbance. Many web-building species common to older forests either survived harvesting, or re-colonized harvest-origin stands more rapidly than they re-colonized fire-origin stands. Cluster analyses and DCA ordination show faunal convergence by ca 30 years after wildfire and harvesting; trajectories in re-colonization, however, differed by disturbance type as the succession of spider assemblages from fire-origin stands lagged behind spider succession in harvest-origin stands. Comparison with cluster analyses using vegetation data and abiotic site conditions suggests spider assemblages recover from harvesting and fire more rapidly than do a variety of other site characteristics. Several spider species (e.g. Gnaphosa borea Kulczynski, Pirata bryantae Kurata, Arctosa alpigena (Doleschall) appear dependent on some of the conditions associated with wildfires as they were absent or rarely collected in harvest-origin stands.

Insects are particularly vulnerable to rapid environmental changes, which are disproportionally affecting high latitudes. Increased temperature could influence insect species differentially and reshape assemblages over time. We quantified temporal assemblage turnover of Arctic Diptera (flies) in the Muscidae, one of the most diverse and abundant families of Arctic insects, using time series data from Zackenberg, north‐east Greenland. We measured temporal patterns of abundance, diversity, and composition of muscid assemblages in wet fen, mesic and arid heath habitats from yearly collections spanning 1996–2014 and tested their relationship to climate. A total of 18 385 individuals representing 16 species of muscid flies were identified. A significant decrease of 80% of total muscid abundance was observed during the study period. Species richness declined in each habitat type but this trend was not significant across habitats. The number of common and abundant species also decreased significantly over time across habitats revealing a temporal modification of species evenness. Significant temporal changes in composition observed in the wet fen and across habitats were mainly driven by a change in relative abundance of certain species rather than by species replacement. Shift in composition in each habitat and decline in muscid abundance across habitats were associated with summer temperature, which has significantly increased over the study period. However, relationships between temperature and muscid abundance at the species level were noticeable for a few species only. Significant directional change in composition was documented in the wet fen but no biotic homogenization across habitats was observed. As one of the few studies of species‐level changes in abundance, diversity and composition of an insect taxon in the Arctic over the past two decades, our study shows that habitat types may modulate insect species responses to recent climate change and that contrasting species responses can alter species assemblages within a few decades.

For over three decades, the importance of taxon sampling curves for comparative biodiversity studies has been repeatedly stated. However, many entomologists (both within Canada and worldwide) continue to publish studies without standardizing their data to take sampling effort into account. We present a case study to illustrate the importance of such standardization, using the collection of spiders (Araneae) by pitfall traps as model data. Data were analyzed using rarefaction to represent one example of a taxon sampling curve, and by a variety of traditional diversity indices to describe alpha diversity. Raw species richness and single-index diversity measures (Shannon–Wiener, Simpson's, and Fisher's α) provided contradictory results. Rarefied species richness standardized to the number of individuals collected enabled more accurate comparisons of diversity and revealed when sampling was insufficient. Focusing on arthropods occurring in forested ecosystems, we also examined the use of taxon sampling curves in current literature by reviewing 133 published articles from 14 journals. Only 26% of the published articles in our review used a taxon sampling curve, and raw species richness and the Shannon–Wiener index of diversity were the most commonly used estimates. There is clearly a need to modify how alpha diversity is measured and compared for arthropod biodiversity studies. We recommend the abandonment of both raw species richness and single-index measures of diversity, and reiterate the need to use rarefaction or a related technique that allows for meaningful comparisons of species richness while taking into account sampling effort.

Urbanization causes the fragmentation of natural habitats into isolated patches surrounded by anthropogenic habitats. Fragment size and the intensity of human disturbance have been shown to affect both composition and diversity of arthropod communities, but most groups have been understudied. We investigated effects of urbanization on ant assemblages (Hymenoptera: Formicidae) in and around the Molson Reserve, a preserved maple-beech forest surrounded by residential properties near Montréal, Quebec. We studied how local ant assemblages differed in terms of composition, abundance, and species richness, depending on whether they were situated in the interior forest, in adjacent residential backyards, or at the edge between these two habitats. We also compared an intact forest interior with a younger and moderately disturbed forest (“buffer zone”) between the urban matrix and the interior forest. Few differences were detected between the buffer zone and the intact forest interior. Extrapolated estimates of species richness suggest that it is lowest in the forest interior and highest in urban zones. Community composition, as investigated with ordination analysis, revealed a clear difference between the fauna of urban sites and the fauna of edges and forest interiors, and analyzing the relative abundance of ants showed residential backyards to contain the most ants. Urban assemblages were characterized by several competitively dominant species, including one introduced or “tramp” species. The occurrence of aggressive and dominant species in urban sites and at the edges of the Molson Reserve could potentially interfere with the dispersal and immigration of ground-dwelling arthropods and negatively affect local diversity or community composition in isolated forest reserves in urban centres.