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Animals commonly exhibit a tendency to return to previously visited locations. Such tendency is manifested at different scales, for example, fidelity to a site or fidelity to a specific patch within a site. Although patch fidelity has important implications for the pollinators and the plants they visit, our understanding of patch fidelity, and the extent to which it varies among bee species, remains limited. Here, we used a mark–reobservation approach to compare patch fidelity and patch size preference between one bumble bee and one honey bee species foraging on patches of Medicago sativa L. Honey bees exhibited greater patch fidelity (76%) than bumble bees (47%); they were more likely to return to the patch where they were marked. Patch size affected the level of patch fidelity for bumble bees but not for honey bees. Bumble bees were more likely to return to larger rather than smaller patches. In addition to patch fidelity, we detected preference of bees for the larger patches. Bees visited the larger patches more often than the smaller patches. These results add patch fidelity to the already known repertoire of differences in foraging strategies between a bumble bee and a honey bee species. It also indicates how the simultaneous study of distinct species in a similar environment can reveal important previously undetected information about their behavioral ecology. Observed differences in patch fidelity and patch size preferences may have important implications for crop pollination and conservation habitat design.

In this study, a novel technique to achieve multi-band performance for both reduced and conventional size circular microstrip patch antennas loaded with metamaterial has been proposed. Incorporation of symmetric slotting concept with the concept of additional mode modification for both MNG (µ negative) and ENG (ɛ negative) metamaterial loaded circular patch antennas have been shown. The use of metamaterial creates an unconventional mode, whereas symmetrical slotting not only modifies another band but also improves the gain by around 1 dB of unconventional mode for MNG loaded antenna. Design algorithms for metamaterial loaded circular patch antennas have been developed to achieve size reduction and highly directive multiband property. Based on these design algorithms, at first a reduced size triple band circular patch antenna loaded with MNG metamaterial has been shown where around 35% size reduction is achievable. Later, a triple band conventional size circular patch antenna partially loaded with ENG metamaterial has been designed with high gain and directive performances for all three bands compared to previously reported such antennas.

1. Habitat edges are thought to explain much of the negative effects arising from habitat fragmentation; however, progress has been limited in extrapolating edge effects to different situations because ecologists still do not understand if and how multiple edges interact within fragments. It also remains controversial whether edge effects govern patch-size effects, such as area sensitivity, observed in many migratory songbirds. 2. I examined how multiple edges within fragments may intensify edge responses by investigating spatial distributions of an area-sensitive songbird that breeds in temperate grasslands of North America, the bobolink (Dolichonyx oryzivorus Linnaeus). I tested whether bobolinks avoid edges and whether avoidance is stronger near two edges (double-edge plots) than near only one edge (single-edge plots). I subsequently linked bobolink distributions to landscape maps that vary in the amount of habitat and degree of fragmentation to explore some potential implications of multiple edges on patch- and landscape-level distributions. 3. Multiple edges appeared to influence the magnitude of observed edge effects, in which the probability of bobolink occurrence was four times lower in double-edge plots and two times lower in single-edge plots than in the interior of grasslands. Within single-edge plots, the probability of occurrence increased with increasing distance from edge. Within double-edge plots, the probability of occurrence increased as a function of the nearest and next-nearest distances from edges. Multiple edges also appeared to increase the extent of edge effects, or distance of edge influence, which was estimated to be approximately 11-33% greater in double-edge plots than in single-edge plots, depending on the next-nearest distance from edge. 4. Extrapolating local bird distributions to landscape models suggests that edge effects can have strong influences on large-scale distributions and that models incorporating multiple edge effects are different to simple nearest-edge models only in highly fragmented landscapes, regardless of landscape composition. Furthermore, edge effects can lead to patch-size effects similar to empirical patterns of area sensitivity observed in this species. I conclude that edge effects can be intensified when multiple edges collide, a feature that permeates many fragmented landscapes.

Because patch size and connectivity may strongly impact the assemblage of species that occur on a patch, the types of food-web interactions that occur among those species may also depend on spatial structure. Here, we identify whether food-web interactions among salt-marsh-inhabiting arthropods vary with patch size and connectivity, and how such changes in trophic structure might feed back to influence the spatial distribution of prey. In a multiyear survey, patch-restricted predators exhibited steeper occupancy-patch-size relationships than herbivores, and species' critical patch sizes were correlated with overall rarity. As a result, the presence of food-web modules depended strongly on patch size: large and well-connected patches supported complex food-web modules, but only the simplest modules involving the most abundant species were found on small patches. Habitat-generalist spiders dominated on small patches, and predation pressure from such species may contribute to the observed lower densities of mesopredators on small patches. Overall, patch size and connectivity influenced the types of modules present on a patch through differential loss of rare, patch-restricted predators, but predation by generalist predators may be a key mechanism influencing the spatial structure of certain prey species.

Background The principle that a single large habitat patch should hold more species than several small patches totalling the same area (SL > SS) is used by conservation agencies to favour protection of large, contiguous areas. Previous reviews of empirical studies have found the opposite, SS > SL, creating the single large or several small (SLOSS) debate. Aims Review the empirical and theoretical SLOSS literature; identify potential mechanisms underlying the SS > SL pattern; evaluate these where possible. Location Global. Time period 1976–2018. Major taxa Plants, invertebrates, vertebrates. Methods Literature review. Results Like previous reviews, I found that SS > SL dominates empirical findings. This pattern remained, although it was somewhat weakened, in studies where sampling intensity was proportional to patch size. I found six classes of theory, and conducted five preliminary evaluations of theory. None of the predictions was supported. The SS > SL pattern held for specialist species groups, suggesting it does not result from incursion by generalists into small patches. I found no evidence for the prediction that the reverse pattern (SL > SS) becomes more common over time since patch creation, through gradual species losses from SS. I found no difference between results for natural and anthropogenic patches. There was also no evidence for predictions that SL > SS is more common when the matrix is more hostile, or for stable than ephemeral patches. Main conclusions Most empirical comparisons find SS > SL. While there are several potential causes, more empirical work is needed to identify those at play. Meanwhile, conservation practitioners should understand that there is no ecological evidence supporting a general principle to preserve large, contiguous habitat areas rather than multiple small areas of the same total size.

In this essay: I provide a brief history of habitat fragmentation research; I describe why its “non-questions” (‘Is habitat fragmentation a big problem for wildlife species?” and, “Are the effects of habitat fragmentation generally negative or positive?”) are important to conservation; I outline my role in tackling these questions; I discuss reasons why the culture of habitat fragmentation research is largely incapable of accepting the answers; and I speculate on the future of habitat fragmentation research.

Aim: Elucidating patterns in species responses to habitat fragmentation is an important focus of ecology and conservation, but studies are often geographically restricted, taxonomically narrow or use indirect measures of species vulnerability. We investigated predictors of species presence after fragmentation using data from studies around the world that included all four terrestrial vertebrate classes, thus allowing direct inter-taxonomic comparison. Location: World-wide. Methods: We used generalized linear mixed-effect models in an information theoretic framework to assess the factors that explained species presence in remnant habitat patches (3342 patches; 1559 species, mostly birds; and 65,695 records of patch-specific presence-absence). We developed a novel metric of fragmentation sensitivity, defined as the maximum rate of change in probability of presence with changing patch size ('Peak Change'), to distinguish between general rarity on the landscape and sensitivity to fragmentation per se. Results: Size of remnant habitat patches was the most important driver of species presence. Across all classes, habitat specialists, carnivores and larger species had a lower probability of presence, and those effects were substantially modified by interactions. Sensitivity to fragmentation (measured by Peak Change) was influenced primarily by habitat type and specialization, but also by fecundity, life span and body mass. Reptiles were more sensitive than other classes. Grassland species had a lower probability of presence, though sample size was relatively small, but forest and shrubland species were more sensitive. Main conclusions: Habitat relationships were more important than lifehistory characteristics in predicting the effects of fragmentation. Habitat specialization increased sensitivity to fragmentation and interacted with class and habitat type; forest specialists and habitat-specific reptiles were particularly sensitive to fragmentation. Our results suggest that when conservationists are faced with disturbances that could fragment habitat they should pay particular attention to specialists, particularly reptiles. Further, our results highlight that the probability of presence in fragmented landscapes and true sensitivity to fragmentation are predicted by different factors.

Habitat fragmentation threatens plant and pollinator communities, as well as their interactions. However, the effects of landscape fragmentation on the pollination of wild plant species are not well understood yet, partly because there are many correlated features in fragmented landscapes (e.g., decreased patch size, increased isolation, and patch complexity) whose influences are difficult to disentangle. Using a structural equation modeling approach, we assessed the direct and indirect effects of landscape fragmentation (patch size, isolation and complexity, percentage of surrounding land in forest) on the abundance, functional-group richness, and evenness of pollinators of 24 habitat fragments within an agricultural landscape in Southern Norway. In addition, we studied how these variables affected visitation rates (visits per flower) and seed production (seed set, seed mass) in the four most abundant plant species in the area. Flower abundance was higher in larger and complex patches and decreased with the percentage of forest in the surroundings, while flower richness increased with patch complexity. We found a direct negative relationship between patch complexity and the overall number of pollinator visits that the habitat fragments received. Apart from this direct landscape effect, pollinator visits were mostly affected by the floral communities, with overall flower abundance and richness increasing both total number of pollinator visits and pollinator-group richness, and flower richness having an additional negative influence on pollinator-group evenness. Interestingly, we did not find any direct link between visitation rates and reproductive success for any of the study plant species. Instead, several landscape variables directly affected species seed production, although the effects of landscape on seed production were highly species specific. Patch complexity had a negative effect on seed production in two of the four focal species, while other components of the landscape had species-specific effects. Increasing fragmentation of agricultural landscapes affects pollination interactions at the community level and the reproduction of wild plants. However, understanding the effects of fragmentation on seed production requires going beyond estimating visitation rates, since landscape effects on plant reproduction are not always related to overall interaction frequencies.

CONTEXT: More than a century of forest and fire management of Inland Pacific landscapes has transformed their successional and disturbance dynamics. Regional connectivity of many terrestrial and aquatic habitats is fragmented, flows of some ecological and physical processes have been altered in space and time, and the frequency, size and intensity of many disturbances that configure these habitats have been altered. Current efforts to address these impacts yield a small footprint in comparison to wildfires and insect outbreaks. Moreover, many current projects emphasize thinning and fuels reduction within individual forest stands, while overlooking large-scale habitat connectivity and disturbance flow issues. METHODS: We provide a framework for landscape restoration, offering seven principles. We discuss their implication for management, and illustrate their application with examples. RESULTS: Historical forests were spatially heterogeneous at multiple scales. Heterogeneity was the result of variability and interactions among native ecological patterns and processes, including successional and disturbance processes regulated by climatic and topographic drivers. Native flora and fauna were adapted to these conditions, which conferred a measure of resilience to variability in climate and recurrent contagious disturbances. CONCLUSIONS: To restore key characteristics of this resilience to current landscapes, planning and management are needed at ecoregion, local landscape, successional patch, and tree neighborhood scales. Restoration that works effectively across ownerships and allocations will require active thinking about landscapes as socio-ecological systems that provide services to people within the finite capacities of ecosystems. We focus attention on landscape-level prescriptions as foundational to restoration planning and execution.

A number of ecosystems can exhibit abrupt shifts between alternative stable states. Because of their important ecological and economic consequences, recent research has focused on devising early warning signals for anticipating such abrupt ecological transitions. In particular, theoretical studies show that changes in spatial characteristics of the system could provide early warnings of approaching transitions. However, the empirical validation of these indicators lag behind their theoretical developments. Here, we summarize a range of currently available spatial early warning signals, suggest potential null models to interpret their trends, and apply them to three simulated spatial data sets of systems undergoing an abrupt transition. In addition to providing a step-by-step methodology for applying these signals to spatial data sets, we propose a statistical toolbox that may be used to help detect approaching transitions in a wide range of spatial data. We hope that our methodology together with the computer codes will stimulate the application and testing of spatial early warning signals on real spatial data.