Patterns Of Resource Availability Research Articles

Stand spatial structure outcomes of forest adaptation treatments in northern hardwood forests in North America

Spatial arrangement of trees is determined by a complex suite of factors, including disturbance history, competition, and resource availability. These spatial patterns drive adaptive capacity by influencing arrangement of growing space, neighborhood competitive relationships, and disturbance response, with irregular patterns supporting higher adaptive capacity. While spatial structure in relation to disturbance and climate change resilience has been studied in dry conifer forests and old-growth temperate forests, it has never been explored in the context of climate adaptive management in mesic, second-growth forests. To address this gap, we analyzed tree spatial patterns in second-growth northern hardwood forests under four different climate adaptation management approaches: no action; resistance or resilience to impacts of climate change; and transition to future-adapted forest types. We used spatial point statistics approaches to describe how patterns differed among the four treatments. We found that the treatments focused on future adaptation led to patterns with variable tree spacing and clumping, while those focused on perpetuating current conditions resulted in less pattern variation. This indicates that adaptation strategies that include uneven-aged regeneration methods that restore and maintain tree spatial patterns historically generated by gap dynamics can be successful in altering resource availability patterns and adaptation space in forest stands.

Alternating selection for dispersal and multicellularity favors regulated life cycles

The evolution of complex multicellularity opened paths to increased morphological diversity and organizational novelty. This transition involved three processes: cells remained attached to one another to form groups, cells within these groups differentiated to perform different tasks, and the groups evolved new reproductive strategies.1,2,3,4,5 Recent experiments identified selective pressures and mutations that can drive the emergence of simple multicellularity and cell differentiation,6,7,8,9,10,11 but the evolution of life cycles, particularly how simple multicellular forms reproduce, has been understudied. The selective pressure and mechanisms that produced a regular alternation between single cells and multicellular collectives are still unclear.12 To probe the factors regulating simple multicellular life cycles, we examined a collection of wild isolates of the budding yeast S.cerevisiae.12,13 We found that all these strains can exist as multicellular clusters, a phenotype that is controlled by the mating-type locus and strongly influenced by the nutritional environment. Inspired by this variation, we engineered inducible dispersal in a multicellular laboratory strain and demonstrated that a regulated life cycle has an advantage over constitutively single-celled or constitutively multicellular life cycles when the environment alternates between favoring intercellular cooperation (a low sucrose concentration) and dispersal (a patchy environment generated by emulsion). Our results suggest that the separation of mother and daughter cells is under selection in wild isolates and is regulated by their genetic composition and the environments they encounter and that alternating patterns of resource availability may have played a role in the evolution of life cycles.

Sedimentary Organic Matter Shapes Macrofaunal Communities but Not Benthic Nutrient Fluxes in Contrasting Habitats Along the Northwest Atlantic Continental Margin

The heterogeneous topography of continental margins can influence patterns of resource availability and biodiversity in deep-sea sediments, potentially altering ecosystem functioning (e.g., organic matter remineralization). Noting a lack of studies that address the latter, we contrasted spatial patterns and drivers of benthic nutrient fluxes and multiple characteristics of macrofaunal communities in shelf, slope, canyon and inter-canyon sedimentary habitats along the Northwest Atlantic continental margin. Replicate sediment push cores were collected from 10 stations (229–996 m depth), incubated for ∼48 h to estimate fluxes of nitrate, nitrite, ammonium, phosphate, and silicate (as a measure of organic matter remineralization) and subsequently analyzed to characterize macrofaunal communities. We also considered various environmental factors, including sedimentary organic matter quantity and quality, and assessed their influence on fluxes and macrofauna. Comparatively high macrofaunal density and distinct community composition and trait expression characterized Georges Canyon, where elevated sedimentary organic matter suggested important lateral transport mechanisms along this canyon axis, with deposition of organic matter strongly affecting biological communities but not benthic nutrient fluxes. Lower penetration of macrofauna into the sediments, distinct community composition, biological traits, and higher nutrient flux rates characterized inter-canyon habitats compared to slope habitats at similar depths. Within inter-canyons, intermediate to low organic matter suggested hydrodynamic forces inhibiting organic matter deposition, affecting biological and functional processes. The input of fresh phytodetritus to the seafloor was the best predictor of macrofaunal density and diversity and contributed to variation in macrofaunal community composition and biological trait expression, together with latitude, depth, and other measures of organic matter quantity and quality. Benthic nutrient fluxes revealed complex variation, with disproportionate effects of few key macrofaunal taxa, together with bottom water oxygen concentration, and sediment granulometry. Our results suggest a relationship between resource availability and macrofaunal density, diversity, and taxonomic and trait composition, whereas organic matter remineralization exhibited a more complex response, which we suggest reflected variation in hydrodynamics and/or physical disturbance in heterogeneous continental margin habitats.

Flexible use of a dynamic energy landscape buffers a marine predator against extreme climate variability.

Animal migrations track predictable seasonal patterns of resource availability and suitable thermal habitat. As climate change alters this ‘energy landscape’, some migratory species may struggle to adapt. We examined how climate variability influences movements, thermal habitat selection and energy intake by juvenile Pacific bluefin tuna (Thunnus orientalis) during seasonal foraging migrations in the California Current. We tracked 242 tuna across 15 years (2002–2016) with high-resolution archival tags, estimating their daily energy intake via abdominal warming associated with digestion (the ‘heat increment of feeding’). The poleward extent of foraging migrations was flexible in response to climate variability, allowing tuna to track poleward displacements of thermal habitat where their standard metabolic rates were minimized. During a marine heatwave that saw temperature anomalies of up to +2.5°C in the California Current, spatially explicit energy intake by tuna was approximately 15% lower than average. However, by shifting their mean seasonal migration approximately 900 km poleward, tuna remained in waters within their optimal temperature range and increased their energy intake. Our findings illustrate how tradeoffs between physiology and prey availability structure migration in a highly mobile vertebrate, and suggest that flexible migration strategies can buffer animals against energetic costs associated with climate variability and change.

Habitat resilience for songbirds: The role of topographic position in a mixed deciduous forest

Climate change is altering patterns of resource availability and this may have negative effects on insectivorous forest birds in the US upper Midwest. As invertebrate life cycle phenology shifts due to earlier spring leaf-out, nesting birds are vulnerable to phenological mismatches between food supply and demand. Areas with complex topography, and thus a variety of thermal and humidity conditions, may support a greater variety of plant and invertebrate phenological rates and stages within close proximity than are found in areas with simple topography. However, the extent and magnitude of this phenomenon is unclear, as is the degree to which topographic position may influence the ability of species to persist during extreme conditions. We examined the effects of topographic position on the phenology of a tri-trophic forest system over two years from spring through mid-summer. We hypothesized that in cool microsites the likelihood of trophic mismatches and late season food shortages is lower than in warm microsites. At 70 sites in the Baraboo Hills, part of the Driftless Area of the US Midwest, we recorded leaf-out timing of over 700 deciduous trees, measured weekly changes in invertebrate biomass on understory foliage, and conducted bird point counts to assess avian species richness and density. In stream gorges, cooler temperatures were associated with slight but significant delays in leaf-out timing of canopy and understory deciduous trees relative to upland sites. At all sites, invertebrate biomass was distributed relatively evenly across the study period, in contrast to other temperate zone sites where phenological mismatches have been reported between birds and their invertebrate prey. Invertebrate biomass was similar in stream gorges and uplands in both study years. Insectivorous bird species richness was greater in stream gorges than in the surrounding upland forest during both seasons and was positively related to Lepidoptera larvae biomass in the understory. Among eight abundant insectivorous bird species, density was similar in uplands and stream gorges, among four species density was higher in uplands, and density of two species was higher in stream gorges. These results suggest that insectivorous birds within this study area are unlikely to experience trophic mismatches, and that despite having cooler microclimates and higher avian species richness, stream gorges did not provide more invertebrate food resources than uplands under the climate conditions of the years in which we sampled this tri-trophic system.

Gradients in Primary Production Predict Trophic Strategies of Mixotrophic Corals across Spatial Scales

Mixotrophy is among the most successful nutritional strategies in terrestrial and marine ecosystems. The ability of organisms to supplement primary nutritional modes along continua of autotrophy and heterotrophy fosters trophic flexibility that can sustain metabolic demands under variable or stressful conditions. Symbiotic, reef-building corals are among the most broadly distributed and ecologically important mixotrophs, yet we lack a basic understanding of how they modify their use of autotrophy and heterotrophy across gradients of food availability. Here, we evaluate how one coral species, Pocillopora meandrina, supplements autotrophic nutrition through heterotrophy within an archipelago and test whether this pattern holds across species globally. Using stable isotope analysis (δ13C) and satellite-derived estimates of nearshore primary production (chlorophyll-a, as a proxy for food availability), we show that P.meandrina incorporates a greater proportion of carbon via heterotrophy when more food is available across five central Pacific islands. We then show that this pattern is consistent globally using data from 15coral species across 16 locations spanning the Caribbean Sea and the Indian and Pacific Oceans. Globally, surface chlorophyll-a explains 77% of the variation in coral heterotrophic nutrition, 86% for one genus across 10 islands, and 94% when controlling for coral taxonomy within archipelagos. These results demonstrate, for the first time, that satellite-derived estimates of nearshore primary production provide a globally relevant proxy for resource availability that can explain variation in coral trophic ecology. Thus, our model provides a pivotal step toward resolving the biophysical couplings between mixotrophic organisms and spatial patterns of resource availability in the coastal oceans.

Text On Screen: Can Emotionally Incongruent Combinations of Media Frames and Messages Elicit Coactivation in the Motivational Systems

ABSTRACTSocial media is becoming one of the most common deployment methods for antidrug and risk message campaigns. This is largely due to the low cost and high distribution that social media affords. This article argues that the social media approach to antidrug messaging also results in greater attention to the message over time. This article reports results from a study that examined how the combination of a short gain-or-loss framed text message interacts with a subsequent pleasant or unpleasant antidrug video message to influence motivational activation and information processing. Based on previous work investigating how different emotional trajectories in public service announcements (PSAs) elicit different patterns of motivational activation and cognitive processing, it was predicted, and found, that emotionally incongruent combinations of the text frame and video content resulted in the coactivation of the motivational systems. Placing a gain frame before a video message affects the overall processing of the subsequent message such that even an unpleasant message is rated more positively and results in a pattern of resource availability more like what we see for pleasant messages. Motivational activation and the subsequent effects on cognitive and emotional reactions are discussed within the context of multi-modal anti-drug campaigns.

Floodplain ecosystem dynamics under extreme dry and wet phases in semi‐arid Australia

Abstract Ecological networks are a cornerstone of ecological theory, offering an integrated approach to understanding food webs and ecosystem dynamics required for restoration and conservation ecology. We investigated ecological network dynamics in a large floodplain undergoing extreme variation in water availability, with drought and subsequent flooding representing a resource pulse. We used structural equation models to quantify ecological network dynamics for the Lowbidgee floodplain (Australia), based on surveys over 5 years while the floodplain transitioned from extremely dry (2009, 2010) to wet (2011) and post‐wet (2013, 2014) conditions. We identified significant associations of species and trophic guilds with inundation at the site and floodplain scale, which allowed us to quantify the strength of biotic interactions within the network and the stability of interactions under differing patterns of resource availability. At the floodplain scale, most taxa responded strongly in distribution and abundance to the 2011 resource pulse, a widespread flood, but this response did not persist during subsequent years of moderate floods. In contrast, fish species, both native and exotic, responded strongly only in the post‐wet period. At the fine spatial scale (i.e., sites), complex responses were observed, with only waterbirds, frogs and tadpoles positively associated with inundation, while fish species showed a range of associations with fine‐scale inundation. Biotic interactions within sites, across all trophic guilds, were predominately overridden by inundation and water temperature, mediated by strong associations with aquatic vegetation. Stratifying the ecological network to dry, wet and post‐wet periods highlighted varying associations of taxa with fine‐scale inundation, generally responding synchronously to resource pulses, with relatively weak biotic interactions. Associations with site‐scale inundation were strongest during the post‐wet period for fishes and frogs. Only Litoria spp. (Hylidae) tadpoles, waterbirds and aquatic vegetation had positive associations with site‐scale inundation during the dry period. We conclude that responses of trophic guilds are largely dependent on the way they interact with their environment at particular spatial and temporal scales. Our investigation of this ecological network reinforced the importance of hydrological drivers over biotic interactions, with clear implications for the management of environmental flows, particularly in systems recovering from long‐term flow alteration. Management efforts should focus environmental flows to promote specialist species (e.g., southern bell frog, Litoria raniformis) and Murray hardyhead (Craterocephalus fluviatilis: Atherinidae), waterbirds and aquatic vegetation over the more generalist fish species that have established because of the loss of the natural flow regime.

Mediterranean mesocarnivores in spatially structured managed landscapes: community organisation in time and space

In the multi-functional and biodiverse cork oak landscapes of Iberia (Montado), agro-silvo-pastoral practices promote landscape heterogeneity and create intricate habitat and resource availability patterns. We used camera-traps to investigate the temporal and spatial organisation of a mesocarnivore community in a Montado landscape in central Portugal. The target carnivore assemblage was largely dominated by three generalist species – the red fox Vulpes vulpes, the European badger Meles meles and the Egyptian mongoose Herpestes ichneumon – while remaining community members – the common genet Genetta genetta and the feral cat Felis silvestris spp. – exhibited restricted distributions. Interspecific differences in activity rhythms and habitat use were particularly marked among widespread species. Low temporal overlap was reported between the diurnal mongoose and predominantly nocturnal red fox and badger. For the latter two species, contrasting differences in habitat use were associated with anthropogenic-induced environmental heterogeneity. Whereas the red fox used more intensively Montado areas preserving dense shrubby understory and avoided semi-disturbed mosaics of sparse shrubs, the badgers displayed the opposite pattern. Our findings add to previous evidence suggesting that the spatial structure created in highly managed landscapes, particularly the diversity of resulting understory structures, promotes the abundance and spread of generalist mesocarnivore species. These may benefit from the surplus of resource amount (e.g. prey) and the creation of different human-made habitats conditions that provide particular combinations of ecological resources favourable to each species requirements. We concur the common view that maintaining understory heterogeneity in Montado landscapes, menaced by current intensification and extensification trends, is important where carnivore persistence is a relevant conservation goal, but alert for potential effects on carnivore assemblages structuring and impacts for specialist species less tolerant to disturbance.

Resource Management for Business Process Scheduling in the Presence of Availability Constraints

In the context of business process management, the resources required by business processes, such as workshop staff, manufacturing machines, etc., tend to follow certain availability patterns, due to maintenance cycles, work shifts and other factors. Such availability patterns heavily influence the efficiency and effectiveness of enterprise resource management. Most existing process scheduling and resource management approaches tend to tune the process structure to seek better resource utilisation, yet neglect the constraints on resource availability. In this article, we investigate the scheduling of business process instances in accordance with resource availability patterns, to find out how enterprise resources can be rationally and sufficiently used. Three heuristic-based planning strategies are proposed to maximise the process instance throughput together with another strategy based on a genetic algorithm. The performance of these strategies has been evaluated by conducting experiments of different settings and analysing the strategy characteristics.

Environmental variability promotes plant invasion

Global environmental change not only entails changes in mean environmental conditions but also in their variability. Changes in climate variability are often associated with altered disturbance regimes and temporal patterns of resource availability. Here we show that increased variability of soil nutrients strongly promotes another key process of global change, plant invasion. In experimental plant communities, the success of one of the world's most invasive plants, Japanese knotweed, is two- to four-fold increased if extra nutrients are not supplied uniformly, but in a single large pulse, or in multiple pulses of different magnitudes. The superior ability to take advantage of variable environments may be a key mechanism of knotweed dominance, and possibly many other plant invaders. Our study demonstrates that increased nutrient variability can promote plant invasion, and that changes in environmental variability may interact with other global change processes and thereby substantially accelerate ecological change.

Phenolic inputs by invasive species could impart seasonal variations in nitrogen pools in the introduced soils: A case study with Polygonum cuspidatum

One cascading feature of the spread of introduced species of plants is their capacity to alter levels of resource availabilities for other species. However, the effects of introduced species on temporal patterns of soil nutrient availability remain unexplored, which could be critical for invasion where the growing seasons are short. To test the hypothesis that the invasive species could alter seasonal patterns of resource availability via suppression of soil processes through secondary compounds in autumnal litter-fall, we measured nutrient dynamics in soils inside and outside stands of invasive Polygonum cuspidatum at four sites in northeastern US over the growing season. In the uppermost soil (0–5 cm depth), both concentrations of inorganic N and rates of N mineralization were 60% lower inside than outside stands of knotweed in spring but became as high or higher inside than outside by fall. Carbon and nitrogen mineralizing soil microbial enzymes also followed a similar seasonal trend with lower activity inside the knotweed stands than outside during spring and these differences disappearing by summer. Concentrations of dissolved organic N (DON) and phenolic compounds showed the opposite seasonal pattern and a strong correlational trend; they were nearly 3 times higher inside than outside stands in spring and similar inside and outside in fall. The estimated flux of tannins from knotweed litter to soil was calculated as 189.5 ± 39.2 g m−2 year−1. Further, exogenous application of knotweed tannin reduced the soil N-mineralization and paralleled the field observed inhibition of mineralization. At 5–15 cm depth, concentrations of phenolics were uniformly low and differences between soils inside and outside stands were mostly non-significant. Our results suggests that invasion by polyphenol rich, yet fast growing exotic species would make the soil N pools more dynamic, which could facilitate invasion by creating stints of apparent deficiency and sufficiency of resources, and due to the localization of the invader effect the amelioration practices could be focused on the surface 0–5 cm layer of the mineral soil.

Effects of human induced land‐use changes on the distribution of the Iberian hare

AbstractLand conversion in Mediterranean Europe has substantially altered the biotic interactions and patterns of resource availability in many ecosystems with serious environmental consequences on some species. Habitat changes are thought to be the main cause of the decline in numbers of European hares, Lepus europaeus, throughout Europe. In contrast, the Iberian hare L. granatensis, in Spain has significantly increased in numbers since the early 1990s. We aimed to investigate changes in habitat favourability of the Iberian hare within municipalities in southern Spain from 1960s to the 1990s. We use predictive distribution models to assess the relationship between the species' distribution, based on hunting yields, and environmental variables by municipality. Our results show that Iberian hare habitat requirements have changed significantly in recent decades from a highly significant association with natural vegetation in the 1960s, to one with cultivated lands in the 1990s. We argue that this shift in habitat may have enabled the Iberian hare to increase in numbers. Habitat heterogeneity at the municipality scale may have benefited Iberian hares, especially within olive groves. Unlike the European hare, which has suffered the conversion from natural vegetation to highly homogeneous, intensively managed landscapes, the Iberian hare in Andalusia has benefited from dry wood crops and irrigated herbaceous crops. These anthropogenic habitats provide year‐round cover and food. However, schemes that target the regeneration of heterogeneity in a variety of landscapes in Andalusia should be encouraged.

Circadian Foraging Rhythms of Bumblebees Monitored by Radio-frequency Identification

Circadian clocks enable organisms to anticipate changes of environmental conditions. In social insects, the colony as a superorganism has a foraging rhythm aligned to the diurnal patterns of resource availability. Within this colony rhythm, the diurnal patterns of individuals are embedded, and various tasks within the colony are performed at different times by different individuals to best serve the colony as a whole. Recent studies have shown that social cues influence the traits of the circadian clock in social insects, but keeping track of the activity of individual workers is not an easy task. Here the authors use fully automatic radio-frequency identification (RFID) to analyze the circadian rhythms of bumblebee foragers (Bombus terrestris) in the normal social context of their nest. They monitored their foraging patterns under different light conditions in the laboratory, including light:dark cycles (LD) as well as constant darkness (DD) and constant light conditions (LL). Their results show that the majority of bumblebee foragers exhibit robust circadian rhythms in LD under laboratory conditions, while they show free-running rhythms both in DD and LL, with free-running periods being significantly shorter in LL conditions. The authors also found that bumblebee workers show an increased level of arrhythmic activity ("death dance") in the hours or days before their death.

Geographic and temporal correlations of mammalian size reconsidered: a resource rule

The tendency of mammals to increase or decrease body size with respect to geography or time depends on the abundance, availability, and size of resources. This dependency accounts for a change in mass with respect to geography, including latitude (Bergmann's rule), a desert existence, and life on oceanic islands (the island rule), as well as in a seasonal anticipation of winter (Dehnel's phenomenon) and a tendency for some lineages to increase in mass through time (Cope's rule). Such a generalized pattern could be called the "resource rule," reflecting the controlling effect of resource availability on body mass and energy expenditure. The correlation of mammalian size with geography and time reflects the impact of temperature, rainfall, and season on primary production, as well as the necessity in the case of some species to share resources with competitors. The inability of the constituent "rules" to account for all size trends often results from unique patterns of resource availability.

Australian waterbirds - time and space travellers in dynamic desert landscapes

Australia’s waterbirds are mostly nomadic, capitalising on highly variable aquatic resources in the arid interior (70% of the continent) for feeding and breeding. Waterbirds, unlike most aquatic organisms, can move between catchments, exploiting habitat wherever it occurs. In Australia, patterns of resource availability for waterbirds are mostly pulsed with peaks of productivity, coinciding with flooding and differing in time and space, affecting individuals, species and functional groups of waterbirds. Australian waterbirds are no different from waterbirds elsewhere, with their behaviour reflecting broad-scale resource availability. They respond to changing patterns of resource distribution, with rapid movements at spatial and temporal scales commensurate with the dynamics of the resource. The most serious conservation threat to waterbirds is a bottleneck in resource availability, leading to population declines, increasingly forced by anthropogenic impacts. River regulation and other threats (e.g. draining) reduce the availability of wetland habitat and decrease the probability of viable resource patches. It is axiomatic that waterbirds need water and such population bottlenecks may occur when the availability of water across the continent is limited. The rehabilitation of regulated rivers with environmental flows and protection of naturally flowing rivers in the arid region are essential for long-term sustainability of Australia’s waterbird populations.

Allocation of effort in artisanal fisheries: The importance of migration and temporary fishing camps

In order to avoid conflicts when spatially explicit rules are implemented, it is critical to understand the spatial distribution of fishing effort, the migration patterns of fishermen and the use of temporary fishing camps. The migration of fishermen is a process shaped by historical patterns of resource availability, in addition to economic and political factors. We present an example in which a temporary fishing camp used for extraction of benthic resources (Loco: Concholepas concholepas) changed into a permanent one during the study period. Throughout the study period fishing effort (trips) was closely related to the productivity of the different fishing grounds, with more trips directed to the most productive areas. The conversion from a temporary to a permanent fishing camp did not improve the efficiency of the loco fishery, but did allow better access to alternative resources (surf clams) on nearby fishing grounds. The succession from simple shelters to a permanent ‘caleta’ is a common situation along the Chilean coast, motivated originally by resource availability and more recently by the creation of the TURF system. In particular the TURF system converts temporary (resource driven) movements of fishermen into rigid stationary caletas, which creates a number of problems. Temporary fishing camps are common when fishing grounds are far from the base port, but they require specific administrative tools in order to achieve sustainable fisheries management.

Habitat quality and among-population differentiation in reproductive effort and flowering phenology in the perennial herb Primula farinosa

In heterogeneous environments, selection on life-history traits and flowering time may vary considerably among populations because of differences in the extent to which mortality is related to age or size, and because of differences in the seasonal patterns of resource availability and intensity of biotic interactions. Spatial variation in optimal reproductive effort and flowering time may result in the evolution of genetic differences in life-history traits, but also in the evolution of adaptive phenotypic plasticity. The perennial herb Primula farinosa occurs at sites that differ widely in soil depth and therefore in water-holding capacity, vegetation cover, and frost-induced soil movement in winter. We used data from eight natural populations and a common-garden experiment to test the predictions that reproductive allocation is negatively correlated with soil depth while age at first reproduction and first flowering date among reproductive individuals are positively correlated with soil depth. In the common-garden experiment, maternal families collected in the field were grown from seed and monitored for 5 years. In the field, reproductive effort (number of flowers in relation to rosette area) varied among populations and was negatively related to soil depth. In the common-garden experiment, among-population differences in age at first reproduction, and reproductive effort were statistically significant, but relatively small and not correlated with soil depth at the site of origin. Flowering time varied considerably among populations, but was not related to soil depth at the site of origin. Taken together, the results suggest that among-population variation in reproductive effort observed in the field largely reflects phenotypic plasticity. They further suggest that among-population differentiation in flowering time cannot be attributed to variation in environmental factors correlated with soil depth.

Temporal Variation in the Availability of Mediterranean Food Resources: Do Badgers Meles meles Track Them?

The Mediterranean landscape of Serra de Grândola, Portugal, is one of many habitats inhabited by Eurasian badgers Meles meles, and in this area, the onset of food availability is seasonally predictable, but abundance is often temporally unpredictable and ephemeral. In our study, we investigated the responses of badgers to the temporal pattern of resource availability. We predicted that they would respond both to the seasonal timing of resource availability and to occasional pulses when food items are superabundant. We hypothesised that badgers' diet would reflect the seasonal onset of specific food resources, closely tracking food abundance, and that this tracking would reflect a relationship between the energetic value and water content of each resource and badger requirements at the time. To evaluate our predictions, we assessed the availability of the primary foods of badgers in Serra de Grândola (i.e. insects and fruits) over four years, and we analysed 120 faecal samples over one year to test for any congruence that might suggest tracking. Fruits and insects showed temporal fluctuations in peaks of availability that occurred on an annual basis, suggesting a temporal pulsing dynamic. Comparison of diet results with phenology and availability of food resources showed a high degree of overlap for practically all main items consumed. Moreover, the consumption of Coleoptera, olives Olea europaea and pears Pyrus bourgaeana appeared to be associated, but only partially, with their availability (rColeoptera = 0.21, P = 0.50; rolives = 0.36, P = 0.24; rpears = 0.20, P = 0.54); whilst acorns Quercus suber were closely tracked (racorns = 0.70, P = 0.01). Orthoptera were the only exception, with a negative relation between consumption and availability (rOthoptera = ‐0.31, P = 0.32). This tracking by badgers of primary resources with temporally differing peaks of availability and abundance appeared to involve trade‐offs with energy and water requirements. Acorns peaked simultaneously with olives which, although not as abundant, had a higher fat content. Other minor fruits (e.g. loquats Eriobotrya japonica and figs Ficus carica) also seemed to be tracked; they were important resources for badgers during summer when air temperatures were high. These results have implications for understanding badger ecology in areas with temporally unpredictable resources.

Comunidade de Carabidae (Coleoptera) em manchas florestais no Pantanal, Mato Grosso do Sul, Brasil

Neste trabalho foi estudado o efeito do tamanho, susceptibilidade à inundação e complexidade vegetacional na estrutura de comunidade de Carabidae (Coleoptera) em ilhas de vegetação arbórea (capões de mata) no Pantanal sul-mato-grossense, sub-regiões Miranda e Abobral. Os dados foram obtidos no período de outubro de 1998 a outubro de 1999 em seis capões de mata, através de 30 armadilhas de queda ("pitfall traps") instaladas por seis dias, mensalmente, no interior dos capões. Foram capturados 2.071 indivíduos, distribuídos em 64 espécies. Negrea scutellaris (Dejean, 1831) e uma espécie não-identificada de Lebiini foram as espécies mais abundantes (com 472 e 464 indivíduos, respectivamente). A distribuição gregária e o elevado número de espécies pouco abundantes encontrados pode refletir o padrão de disponibilidade de recursos das regiões tropicais. Entre as variáveis estudadas, apenas a complexidade vegetacional explicou a variação da riqueza de espécies nos capões de mata. A composição das espécies não foi explicada por nenhuma das variáveis avaliadas. Possivelmente a variação em tamanho e em complexidade vegetacional dos capões não seja tão evidente para demonstrar estas relações e a composição das espécies esteja variando mais em escala regional do que em escala local.