Halpha-Derived Star-Formation Rates For Three z ~ 0.75 EDisCS Galaxy Clusters

We present Halpha-derived star-formation rates (SFRs) for three z ~ 0.75 galaxy clusters. Our 1 sigma flux limit corresponds to a star-formation rate of 0.10-0.24 solar mass per year, and our minimum reliable Halpha + [N II] rest-frame equivalent width is 10\AA. We show that Halpha narrowband imaging is an efficient method for measuring star formation in distant clusters. In two out of three clusters, we find that the fraction of star-forming galaxies increases with projected distance from the cluster center. We also find that the fraction of star-forming galaxies decreases with increasing local galaxy surface density in the same two clusters. We compare the median rate of star formation among star-forming cluster galaxies to a small sample of star-forming field galaxies from the literature and find that the median cluster SFRs are \~50% less than the median field SFR. We characterize cluster evolution in terms of the mass-normalized integrated cluster SFR and find that the z ~ 0.75 clusters have more SFR per cluster mass on average than the z <= 0.4 clusters from the literature. The interpretation of this result is complicated by the dependence of the mass-normalized SFR on cluster mass and the lack of sufficient overlap in the mass ranges covered by the low and high redshift samples. We find that the fraction and luminosities of the brightest starburst galaxies at z ~ 0.75 are consistent with their being progenitors of the post-starburst galaxies at z ~ 0.45 if the post-starburst phase lasts several (~5) times longer than the starburst phase.Comment: Accepted for publication in ApJ, 20 pages, 24 figure

Edge effects: Which one?

L'effet de lisière est souvent invoqué comme explication de la distribution des espèces et des indices de diversité dans les tâches de forêt dans les paysages ruraux. Une analyse de la litterature faisant référence à cette explication montre qu'elle recouvre souvent des processus écologiques différents. Dans cette présentation nous défendons l'idée qu'il y a en fait plusieurs effets de lisières qui sont souvent présentés de façon indifférenciée alors qu'ils concernant des processus différents. Par une analyse à différents niveaux d'organisation de l'hétérogénéité créée par la discontinuité entre un milieu forestier et un milieu non forestier, nous montrons que l'on identifie différents effets de lisières sur la distribution des espèces. Nous montrons notamment que les effets de lisières observables sur un segment de lisière ne sont pas les mêmes que ceux qui concernent l'ensemble de la lisière d'un bois formée de plusieurs segments, alors que dans la littérature on trouve souvent une confusion entre ces deux niveaux. Une terminologie plus précise est nécessaire pour identifier les différents effets de lisière et clarifier leurs rôles respectifs afin de mieux les prendre en compte dans la compréhension des processus écologiques induits par les lisières et ainsi mieux gérer la biodiversité et les services écosystémiques qui en dépendent

Habitat filtering by landscape and local forest composition in native and exotic New Zealand birds : Habitat filtering in New Zealand birds

Untangling the relative influences of environmental filtering and biotic interactions on species coexistence at various spatial scales is a long-held issue in community ecology. Separating these processes is especially important to understand the influences of introduced exotic species on the composition of native communities. For this aim, we investigated coexistence patterns in New Zealand exotic and native birds along multiple-scale habitat gradients. We built a Bayesian hierarchical model, contrasting the abundance variations of 10 native and exotic species in 501 point counts spread along landscape and local-scale gradients of forest structure and composition. Although native and exotic species both occurred in a wide range of habitats, they were separated by landscape-level variables. Exotic species were most abundant in exotic conifer plantations embedded in farmland matrices, while native birds predominated in areas dominated by continuous native forest. In exotic plantation forests, and to a lesser extent in native forests, locally co-occurring exotic and native species were segregated along a gradient of vegetation height. These results support the prediction that exotic and native bird species are segregated along gradients related to anthropogenic disturbance and habitat availability. In addition, native and exotic species overlapped little in a multivariate functional space based on 10 life history traits associated with habitat selection. Hence, habitat segregation patterns were probably mediated more by environmental filtering processes than by competition at landscape and local scales

A socio-ecological framework for the analysis of edges dynamics and their consequences on ecosystems services in temperate landscapes

The 2015 World Congress was a joint meeting between the International Association of Landscape Ecology World Congress (WC) and the U.S. chapter of IALE (US-IALE), held at the Hilton Portland & Executive Tower in Portland, Oregon, July 5 - 10, 2015. The theme was: Crossing Scales, Crossing Borders: Global Approaches to Complex Challenges. The meeting brought together nearly 1,000 leaders in landscape ecology from around the globe, including educators and practitioners in the fields of geology, ecology, biology, geography, and landscape preservation and design, dedicated to preserving and protecting our natural resources

Edge contrast does not modulate edge effect on plants and pollinators

Edge contrast, is one of the main determinants of edge effects. This study examines the response of plant and pollinator diversity (bees and butterflies) to forest edge contrast, i.e. the difference between forests and adjacent open habitats with different disturbance regimes. We also investigated a potential cascading effect from plants to pollinators and whether edge structure and landscape composition mediate the relationship between edge contrast and beta diversity of pollinators. We sampled 51 lowcontrast edges where forests were adjacent to habitats showing low levels of disturbance (i.e. grey dunes, mowed fire-breaks, orchards, grasslands) and 29 high-contrast edges where forests were adjacent to more intensively disturbed habitats (i.e. tilled firebreaks, oilseed rape) in three regions of France. We showed that plant diversities were higher in edges than in adjacent open habitat, whatever the edge contrast. However, plant beta diversity did not differ significantly between low and highcontrast edges. While we observed higher pollinator diversities in adjacent habitats than in low-contrast edges, there were no significant differences in pollinator beta diversity depending on edge contrast. We did not observe a cascading effect from plants to pollinators. Plant and bee beta diversities were mainly explained by local factors (edge structure and flower cover) while butterfly beta diversity was explained by surrounding landscape characteristics (proportion of land cover in grassland)

Tree size, microhabitat diversity and landscape structure determine the value of isolated trees for bats in farmland

Isolated trees are increasingly recognised as playing a vital role in supporting biodiversity in agricultural landscapes, yet their occurrence has declined substantially in recent decades. Most bats in Europe are tree-dependent species that rely on woody elements in order to persist in farmlands. However, isolated trees are rarely considered in conservation programs and landscape planning. Further investigations are therefore urgently required to identify which trees – based on both their intrinsic characteristics and their location in the landscape – are particularly important for bats. We acoustically surveyed 57 isolated trees for bats to determine the relative and interactive effects of size, tree-related microhabitat (TreM) diversity and surrounding landscape context on bat activity. Tall trees with large diameter at breast height and crown area positively influenced the activity of Pipistrellus pipistrellus and small Myotis bats (Myotis spp.) while smaller and thinner trees favoured M. myotis activity. The diversity of TreMs that can be used as roosts had a positive effect on (i) Barbastella barbastellus activity only when trees were relatively close (10% within 100 radius scale). The potential benefits of isolated trees for bats result from ecological mechanisms operating at both tree and landscape scales, underlining the crucial need for implementing a multi-scale approach in conservation programs. Maintaining the largest and most TreM-diversified trees located in the most heterogeneous agricultural landscapes will provide the greatest benefits

Bat responses to changes in forest composition and prey abundance depend on landscape matrix and stand structure

Despite the key importance of the landscape matrix for bats, we still not fully understand how the effect of forest composition interacts at combined stand and landscape scales to shape bat communities. In addition, we lack detailed knowledge on the effects of local habitat structure on bat-prey relationships in forested landscapes. We tested the assumptions that (i) forest composition has interacting effects on bats between stand and landscape scales; and (ii) stand structure mediates prey abundance effects on bat activity. Our results indicated that in conifer-dominated landscapes (> 80% of coniferous forests) bat activity was higher in stands with a higher proportion of deciduous trees while bats were less active in stands with a higher proportion of deciduous trees in mixed forest landscapes (~ 50% of deciduous forests). Moth abundance was selected in the best models for six among nine bat species. The positive effect of moth abundance on Barbastella barbastellus was mediated by vegetation clutter, with dense understory cover likely reducing prey accessibility. Altogether, our findings deepen our understanding of the ecological processes affecting bats in forest landscapes and strengthen the need to consider both landscape context and trophic linkage when assessing the effects of stand-scale compositional and structural attributes on bats

A global database for metacommunity ecology, integrating species, traits, environment and space

The use of functional information in the form of species traits plays an important role in explaining biodiversity patterns and responses to environmental changes. Although relationships between species composition, their traits, and the environment have been extensively studied on a case-by-case basis, results are variable, and it remains unclear how generalizable these relationships are across ecosystems, taxa and spatial scales. To address this gap, we collated 80 datasets from trait-based studies into a global database for metaCommunity Ecology: Species, Traits, Environment and Space; “CESTES”. Each dataset includes four matrices: species community abundances or presences/absences across multiple sites, species trait information, environmental variables and spatial coordinates of the sampling sites. The CESTES database is a live database: it will be maintained and expanded in the future as new datasets become available. By its harmonized structure, and the diversity of ecosystem types, taxonomic groups, and spatial scales it covers, the CESTES database provides an important opportunity for synthetic trait-based research in community ecology

Landscape composition and life-history traits influence bat movement and space use: Analysis of 30 years of published telemetry data

Aim Animal movement determines home range patterns, which in turn affect individual fitness, population dynamics and ecosystem functioning. Using temperate bats, a group of particular conservation concern, we investigated how morphological traits, habitat specialization and environmental variables affect home range sizes and daily foraging movements, using a compilation of 30 years of published bat telemetry data. Location Northern America and Europe. Time period 1988–2016. Major taxa studied Bats. Methods We compiled data on home range size and mean daily distance between roosts and foraging areas at both colony and individual levels from 166 studies of 3,129 radiotracked individuals of 49 bat species. We calculated multi-scale habitat composition and configuration in the surrounding landscapes of the 165 studied roosts. Using mixed models, we examined the effects of habitat availability and spatial arrangement on bat movements, while accounting for body mass, aspect ratio, wing loading and habitat specialization. Results We found a significant effect of landscape composition on home range size and mean daily distance at both colony and individual levels. On average, home ranges were up to 42% smaller in the most habitat-diversified landscapes while mean daily distances were up to 30% shorter in the most forested landscapes. Bat home range size significantly increased with body mass, wing aspect ratio and wing loading, and decreased with habitat specialization. Main conclusions Promoting bat movements through the landscape surrounding roosts at large spatial scales is crucial for bat conservation. Forest loss and overall landscape homogenization lead temperate bats to fly further to meet their ecological requirements, by increasing home range sizes and daily foraging distances. Both processes might be more detrimental for smaller, habitat-specialized bats, less able to travel increasingly longer distances to meet their diverse needs

Can School Children Support Ecological Research? Lessons from the Oak Bodyguard Citizen Science Project

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