Precipitation alters interactions in a grassland ecological community.

Climate change is transforming precipitation regimes world-wide. Changes in precipitation regimes are known to have powerful effects on plant productivity, but the consequences of these shifts for the dynamics of ecological communities are poorly understood. This knowledge gap hinders our ability to anticipate and mitigate the impacts of climate change on biodiversity. Precipitation may affect fauna through direct effects on physiology, behaviour or demography, through plant-mediated indirect effects, or by modifying interactions among species. In this paper, we examined the response of a semi-arid ecological community to a fivefold change in precipitation over 7 years. We examined the effects of precipitation on the dynamics of a grassland ecosystem in central California from 2007 to 2013. We conducted vegetation surveys, pitfall trapping of invertebrates, visual surveys of lizards and capture-mark-recapture surveys of rodents on 30 plots each year. We used structural equation modelling to evaluate the direct, indirect and modifying effects of precipitation on plants, ants, beetles, orthopterans, kangaroo rats, ground squirrels and lizards. We found pervasive effects of precipitation on the ecological community. Although precipitation increased plant biomass, direct effects on fauna were often stronger than plant-mediated effects. In addition, precipitation altered the sign or strength of consumer-resource and facilitative interactions among the faunal community such that negative or neutral interactions became positive or vice versa with increasing precipitation. These findings indicate that precipitation influences ecological communities in multiple ways beyond its recognized effects on primary productivity. Stochastic variation in precipitation may weaken the average strength of biotic interactions over time, thereby increasing ecosystem stability and resilience to climate change.

Towards Ecological Management and Sustainable Urban Planning in Seoul, South Korea: Mapping Wild Pollinator Habitat Preferences and Corridors Using Citizen Science Data.

The preservation and restoration of habitats and ecological connectivity inside cities is crucial to ensure wildlife can find suitable areas to forage, rest and reproduce, as well as to disperse, thereby allowing metapopulation functioning. In this study, we used data collected by a citizen science program between 2016 and 2018 to determine which families of pollinators were the most frequently observed in Seoul and with which habitats pollinators had the highest affinities. Using species distribution modeling and landscape graph approaches, we located the main habitats and corridors to reinforce connectivity for six pollinator families. Finally, we identified habitats and corridors where conservation actions should be prioritized. In total, 178 species belonging to 128 genera and 60 families were observed. Hymenopterans were the most recorded, followed by dipterans and lepidopterans. The most suitable habitats for pollinators were constituted of public parks, university campuses, and Cultural Heritage sites. In a dense city like Seoul, most of the conservation corridors are located in built-up areas. Innovative urban planning and architecture are therefore required as well as the setting-up of ecological management practices to lead to a more sustainable urbanism for pollinators and wildlife in general.

Modelling the response of urban lichens to broad-scale changes in air pollution and climate.

To create more resilient cities, it is important that we understand the effects of the global change drivers in cities. Biodiversity-based ecological indicators (EIs) can be used for this, as biodiversity is the basis of ecosystem structure, composition, and function. In previous studies, lichens have been used as EIs to monitor the effects of global change drivers in an urban context, but only in single-city studies. Thus, we currently do not understand how lichens are affected by drivers that work on a broader scale. Therefore, our aim was to quantify the variance in lichen biodiversity-based metrics (taxonomic and trait-based) that can be explained by environmental drivers working on a broad spatial scale, in an urban context where local drivers are superimposed. To this end, we performed an unprecedented effort to sample epiphytic lichens in 219 green spaces across a continental gradient from Portugal to Estonia. Twenty-six broad-scale drivers were retrieved, including air pollution and bio-climatic variables, and their dimensionality reduced by means of a principal component analysis (PCA). Thirty-eight lichen metrics were then modelled against the scores of the first two axes of each PCA, and their variance partitioned into pollution and climate components. For the first time, we determined that 15% of the metric variance was explained by broad-scale drivers, with broad-scale air pollution showing more importance than climate across the majority of metrics. Taxonomic metrics were better explained by air pollution, as expected, while climate did not surpass air pollution in any of the trait-based metric groups. Consequently, 85% of the metric variance was shown to occur at the local scale. This suggests that further work is necessary to decipher the effects of climate change. Furthermore, although drivers working within cities are prevailing, both spatial scales must be considered simultaneously if we are to use lichens as EIs in cities at continental to global scales.

A dataset of the flowering plants (Angiospermae) in urban green areas in five European cities.

This article summarizes the data of a survey of flowering plants in 80 sites in five European cities and urban agglomerations (Antwerp, Belgium; greater Paris, France; Poznan, Poland; Tartu, Estonia; and Zurich, Switzerland). Sampling sites were selected based on a double orthogonal gradient of size and connectivity and were urban green areas (e.g. parks, cemeteries). To characterize the flowering plants, two sampling methodologies were applied between April and July 2018. First, a floristic inventory of the occurrence of all flowering plants in the five cities. Second, flower counts in sampling plots of standardized size (1 m2) only in Zurich. We sampled 2146 plant species (contained in 824 genera and 137 families) and across the five cities. For each plant species, we provide its origin status (i.e. whether the plants are native from Europe or not) and 11 functional traits potentially important for plant-pollinator interactions. For each study site, we provide the number of species, genera, and families recorded, the Shannon diversity as well as the proportion of exotic species, herbs, shrubs and trees. In addition, we provide information on the patch size, connectivity, and urban intensity, using four remote sensing-based proxies measured at 100- and 800-m radii.

Assessing the emergence of pro-biodiversity practices in citizen scientists of a backyard butterfly survey.

By monitoring biodiversity through citizen science programs, volunteers help scientists gather data at unprecedented temporal and geographical scales, and increase their knowledge and awareness of the surrounding biodiversity. While scientific outcomes of such programs may in the long run improve the state of biodiversity by informing environmental policies, direct benefits to biodiversity could arise locally if such experience of nature leads to biodiversity-friendly behaviors in volunteers. However, whether engagement into nature-based CS programs promotes individual behavioral changes remains poorly known. Here, we explored whether sustained participation in a nature-based citizen science program, called the French Butterfly citizen science project, is associated with changes in individual gardening practices. Specifically, using information provided by volunteers (n = 2362, from 2006 to 2013), we quantified gardening practices that directly affect butterflies, through two different indices: provision of nectar resources, and pesticide use. We found quantitative evidence that individual gardening practices shifted with multi-year participation, towards increased provision of nectar resources and decreased use of pesticides. However, the reduction in pesticide use was weakened if the backyard was used to grow fruits or vegetables. Other variables such as the size of the backyard affected gardening practices. This study reveals that participation in a nature-based citizen science program can prompt biodiversity-friendly behaviors, and highlights citizen science not only as a way to collect ecologically sound data but also as a direct conservation tool. Yet, future interdisciplinary research remains critical to overcome factors limiting firm adoption of pro-biodiversity behaviors.

Any despot at my table? Competition among native and introduced bird species at garden birdfeeders in winter.

Garden bird feeding constitutes a massive provision of food that can support bird communities, but there is a growing concern it might favour the establishment of exotic species that could be detrimental to others. How bird species compete with novel species for this anthropogenic food resources needs to be assessed. Here, we investigated competition in wintering bird communities at garden birdfeeders. We evaluated whether - and how much - bird access to resources is hampered by the presence of putative superior competing species, among which the Rose-ringed parakeet, the most abundant introduced species across Europe. Using the nation-wide citizen science scheme BirdLab, in which volunteers record in real-time bird attendance on a pair of birdfeeders during 5-minute sessions, we tested whether i) cumulative bird presence time and richness at birdfeeders, and ii) species probability of presence at birdfeeders, were influenced by three large species (the Eurasian magpie, the Eurasian collared-dove, and the Rose-ringed parakeet). Additionally, we assessed whether the Rose-ringed parakeet occupied resources significantly more than others. Presence of the Rose-ringed parakeet or the Eurasian collared-dove similarly reduced community cumulative presence time at birdfeeders, but only the dove reduced community richness. Each of the three large species influenced the presence of at least one of the six smaller species that could be separately modelled, but effects varied in strength and direction. The Rose-ringed parakeet and the Eurasian collared-dove were among the three species monopolising birdfeeders the longest, substantially more than the Eurasian magpie. Our findings confirm the competitive abilities of the large species studied, but do not suggest that garden bird feeding may alarmingly favour introduced species with detrimental effects on native species. Given the variability of large species' effects on small passerines, direct and indirect interactions among all species must be examined to fully understand the ecological net effects at stake.

Functional homogenization of flower visitor communities with urbanization.

Land-use intensification and resulting habitat loss are put forward as the main causes of flower visitor decline. However, the impact of urbanization, the prime driver of land-use intensification in Europe, is poorly studied. In particular, our understanding of whether and how it affects the composition and functioning of flower visitor assemblages is scant, yet required to cope with increasing urbanization worldwide. Here, we use a nation-wide dataset of plant-flower visitor (Coleoptera, Diptera, Hymenoptera, Lepidoptera) interactions sampled by citizen scientists following a standardized protocol to assess macroecological changes in richness and composition of flower visitor communities with urbanization. We measured the community composition by quantifying the relative occurrence of generalist and specialist flower visitors based on their specialisation on flowering plant families. We show that urbanization is associated with reduced flower visitor richness and a shift in community composition toward generalist insects, indicating a modification of the functional composition of communities. These results suggest that urbanization affects not only the richness of flower visitor assemblages but may also cause their large-scale functional homogenization. Future research should focus on designing measures to reconcile urban development with flower visitor conservation.

The whereabouts of flower visitors: contrasting land-use preferences revealed by a country-wide survey based on citizen science.

BACKGROUND: In the past decade, accumulating evidence of pollinator decline has raised concerns regarding the functioning of terrestrial ecosystems and the sustainability of crop production. Although land-use changes have been advanced as the major causes, the affinities of most wild pollinators with the main land-use types remain unknown. Filling this gap in our knowledge is a prerequisite to improving conservation and management programmes. METHODOLOGY/PRINCIPAL FINDINGS: We estimated the affinity of flower visitors with urban, agricultural and natural land-uses using data from a country-wide scale monitoring scheme based on citizen science (Spipoll). We tested whether the affinities differed among insect orders and according to insect frequency (frequent or infrequent). Our results indicate that the affinities with the three land-use types differed among insect orders. Apart from Hymenopterans, which appeared tolerant to the different land-uses, all flower visitors presented a negative affinity with urban areas and a positive affinity with agricultural and natural areas. Additionally, infrequent taxa displayed a lower affinity with urban areas and a higher affinity with natural areas than did frequent taxa. Within frequent taxa, Hymenoptera and Coleoptera included specialists of the three land-use types whereas Diptera and Lepidoptera contained specialists of all but urban areas. CONCLUSIONS/SIGNIFICANCE: Our approach allowed the first standardised evaluation of the affinity of flower visitors with the main land-use types across a broad taxonomical range and a wide geographic scope. Our results suggest that the most detrimental land-use change for flower visitor communities is urbanisation. Moreover, our findings highlight the fact that agricultural areas have the potential to host highly diverse pollinator communities. We suggest that policy makers should, therefore, focus on the implementation of pollinator-friendly practices in agricultural lands. This may be a win-win strategy, as both biodiversity and crop production may benefit from healthier communities of flower visitors in these areas.