bluuebunny/crossref_metadata_2025 huggingface dataset:
Flower color influences insect visitation in alpine New Zealand
Authors: Campbell Diane R. , Bischoff Mascha , Lord Janice M. , Robertson Alastair W.
Published: June 2010

Despite a long‐standing belief that insect pollinators can select for certain flower colors, there are few experimental demonstrations that free‐flying insects choose between natural flowers based on color. We investigated responses of insect visitors to experimental manipulations of flower color in the New Zealand alpine. Native syrphid flies (AllograptaandPlatycheirus) and solitary bees (HylaeusandLeioproctus) showed distinct preferences for visiting certain flower species. These responses were determined, in part, by flower color, as insects also responded to experimental manipulations of visible petal color in 7 out of 11 tests with different combinations of flower species and insect type. When preferences were detected, syrphid flies chose yellow over white petals regardless of flower species, whereasHylaeuschose white over yellowOurisia glandulosa. In some cases, the strength and direction of color preference depended on the context of other floral traits, in which case the response usually favored the familiar, normal combination of traits. Syrphid flies also visited in response to floral morphological traits but did not show preference based on UV reflectance. The unusually high preponderance of white flowers in the New Zealand alpine is not explained by complete generalization of flower color choice. Instead, the insect visitors show preferences based on color, including colors other than white, along with other floral traits. Furthermore, they can respond in complex ways to combinations of floral cues, suggesting that traits may act in nonadditive ways in determining pollinator visitation.
Multistate modeling of habitat dynamics: factors affecting Florida scrub transition probabilities
Authors: Breininger David R. , Nichols James D. , Duncan Brean W. , Stolen Eric D. , Carter Geoffrey M. , Hunt Danny K. , Drese John H.
Published: June 2010

Many ecosystems are influenced by disturbances that create specific successional states and habitat structures that species need to persist. Estimating transition probabilities between habitat states and modeling the factors that influence such transitions have many applications for investigating and managing disturbance‐prone ecosystems. We identify the correspondence between multistate capture–recapture models and Markov models of habitat dynamics. We exploit this correspondence by fitting and comparing competing models of different ecological covariates affecting habitat transition probabilities in Florida scrub and flatwoods, a habitat important to many unique plants and animals. We subdivided a large scrub and flatwoods ecosystem along central Florida's Atlantic coast into 10‐ha grid cells, which approximated average territory size of the threatened Florida Scrub‐Jay (Aphelocoma coerulescens), a management indicator species. We used 1.0‐m resolution aerial imagery for 1994, 1999, and 2004 to classify grid cells into four habitat quality states that were directly related to Florida Scrub‐Jay source–sink dynamics and management decision making. Results showed that static site features related to fire propagation (vegetation type, edges) and temporally varying disturbances (fires, mechanical cutting) best explained transition probabilities. Results indicated that much of the scrub and flatwoods ecosystem was resistant to moving from a degraded state to a desired state without mechanical cutting, an expensive restoration tool. We used habitat models parameterized with the estimated transition probabilities to investigate the consequences of alternative management scenarios on future habitat dynamics. We recommend this multistate modeling approach as being broadly applicable for studying ecosystem, land cover, or habitat dynamics. The approach provides maximum‐likelihood estimates of transition parameters, including precision measures, and can be used to assess evidence among competing ecological models that describe system dynamics.
Dietary flexibility aids Asian earthworm invasion in North American forests
Authors: Zhang Weixin , Hendrix Paul F. , Snyder Bruce A. , Molina Marirosa , Li Jianxiong , Rao Xingquan , Siemann Evan , Fu Shenglei
Published: June 2010

On a local scale, invasiveness of introduced species and invasibility of habitats together determine invasion success. A key issue in invasion ecology has been how to quantify the contribution of species invasiveness and habitat invasibility separately. Conventional approaches, such as comparing the differences in traits and/or impacts of species between native and/or invaded ranges, do not determine the extent to which the performance of invaders is due to either the effects of species traits or habitat characteristics. Here we explore the interaction between two of the most widespread earthworm invaders in the world (Asian Amynthas agrestis and European Lumbricus rubellus) and study the effects of species invasiveness and habitat invasibility separately through an alternative approach of “third habitat” in Tennessee, USA. We propose that feeding behaviors of earthworms will be critical to invasion success because trophic ecology of invasive animals plays a key role in the invasion process. We found that (1) the biomass and isotopic abundances (δ13C and δ15N) of A. agrestis were not impacted by either direct effects of L. rubellus competition or indirect effects of L. rubellus‐preconditioned habitat; (2) A. agrestis disrupted the relationship between L. rubellus and soil microorganisms and consequently hindered litter consumption by L. rubellus; and (3) compared to L. rubellus, A. agrestis shifted its diet more readily to consume more litter, more soil gram‐positive (G+) bacteria (which may be important for litter digestion), and more non‐microbial soil fauna when soil microorganisms were depleted. In conclusion, A. agrestis showed strong invasiveness through its dietary flexibility through diet shifting and superior feeding behavior and its indirectly negative effect of habitat invasibility on L. rubellus via changes in the soil microorganism community. In such context, our results expand on the resource fluctuation hypothesis and support the superior competitor hypothesis. This work presents additional approaches in invasion ecology, provides some new dimensions for further research, and contributes to a greater understanding of the importance of interactions between multiple invading species.
Conserving biodiversity in production landscapes
Authors: Wilson K. A. , Meijaard E. , Drummond S. , Grantham H. S. , Boitani L. , Catullo G. , Christie L. , Dennis R. , Dutton I. , Falcucci A. , Maiorano L. , Possingham H. P. , Rondinini C. , Turner W. R. , Venter O. , Watts M.
Published: June 2010

Alternative land uses make different contributions to the conservation of biodiversity and have different implementation and management costs. Conservation planning analyses to date have generally assumed that land is either protected or unprotected and that the unprotected portion does not contribute to conservation goals. We develop and apply a new planning approach that explicitly accounts for the contribution of a diverse range of land uses to achieving conservation goals. Using East Kalimantan (Indonesian Borneo) as a case study, we prioritize investments in alternative conservation strategies and account for the relative contribution of land uses ranging from production forest to well‐managed protected areas. We employ data on the distribution of mammals and assign species‐specific conservation targets to achieve equitable protection by accounting for life history characteristics and home range sizes. The relative sensitivity of each species to forest degradation determines the contribution of each land use to achieving targets. We compare the cost effectiveness of our approach to a plan that considers only the contribution of protected areas to biodiversity conservation, and to a plan that assumes that the cost of conservation is represented by only the opportunity costs of conservation to the timber industry. Our preliminary results will require further development and substantial stakeholder engagement prior to implementation; nonetheless we reveal that, by accounting for the contribution of unprotected land, we can obtain more refined estimates of the costs of conservation. Using traditional planning approaches would overestimate the cost of achieving the conservation targets by an order of magnitude. Our approach reveals not only where to invest, but which strategies to invest in, in order to effectively and efficiently conserve biodiversity.
Prognosis for ecosystem recovery following rodent eradication and seabird restoration in an island archipelago
Authors: Jones Holly P.
Published: June 2010

Invasive species are widespread and can have devastating effects on biota, especially insular biota. Invasive species eradications are increasingly employed to promote island recovery to preinvasion states. However, it remains unclear if additional restoration actions may be required on islands that were once heavily reliant on seabird guano for ecosystem functions. Active seabird augmentation has been suggested as necessary to exact ecosystem recovery on contemporary timescales in some cases. I use two experiments on offshore islands in Cook Strait, New Zealand, to test the hypothesis that seabird restoration will restore island ecosystem functioning following invasive rodent removal. The first is a small‐scale single‐island fertilization experiment that simulates seabird recovery. This experiment tested the recovery potential of offshore islands and was used to infer the density of seabirds needed to elicit ecosystem recovery. The second is a large‐scale natural experiment that takes advantage of eight islands with differing rodent eradication and seabird restoration histories. I compared ecosystem functioning variables (δ15N, C:N ratios in soil, plants, and spiders, as well as arthropod abundance and diversity) on two islands that had rodents eradicated and two islands undergoing seabird augmentation with two control islands (never invaded by rodents) and two positive control islands (currently invaded by rodents). The results suggest that islands do have the potential for recovery given nutrient amendments, but that islands with rodents eradicated and islands undergoing seabird augmentation have not recovered most of their ecosystem function. Finer, intra‐island analysis showed that seabird restoration projects have the potential to speed the recovery process, but that the projects on the studied seabird restoration islands were not advanced enough to produce island‐wide recovery. The results suggest that high seabird densities (5–10 burrows/m2) are needed to promote recovery to never‐invaded control levels. Seabird augmentation, through chick translocation and/or social facilitation with decoys, vocalization playbacks, and/or mirrors can supplement passive seabird recovery on islands where seabirds have been extirpated or extremely reduced by invasive predators. Such restoration efforts may be necessary to promote ecosystem recovery on contemporary timescales.
Climate controls on grass culm production over a quarter century in a tallgrass prairie
Authors: Craine Joseph M. , Towne E. Gene , Nippert Jesse B.
Published: June 2010

The flowering of grasses is a process critical to plant population dynamics and genetics, herbivore performance, and human health. To better understand the climate factors governing grass flowering, we analyzed the patterns of culm production over 25 years for three perennial tallgrass prairie species at Konza Prairie in Kansas, USA. The three species (Andropogon gerardii, Sorghastrum nutans, and Schizachyrium scoparium) all utilize the C4 photosynthetic pathway and were measured annually at the same locations for the past 25 years in an annually burned watershed. Culm production of all three species increased with higher growing‐season soil moisture and precipitation but differed in their responses to water availability at different times during the growing season. Relative to Andropogon, Sorghastrum responded more to precipitation early in the growing season, and Schizachyrium responded more to precipitation late in the growing season. Flowering by each species also revealed a threshold relationship with late‐season soil moisture at ~1 m depth, which likely is a proxy for season‐long water balance. Although flowering can be influenced by conditions antecedent to the current growing season, neither soil moisture nor precipitation during the previous year influenced flowering over the 25‐year period. Flowering culm production averaged 9% and 7% of total graminoid aboveground net primary production (ANPP) in the uplands and lowlands, respectively. Interannual variation in ANPP correlated only with Sorghastrum flowering, suggesting a predominant role of the species in ANPP responses to climate.
Survivorship patterns in captive mammalian populations: implications for estimating population growth rates
Authors: Lynch Heather J. , Zeigler Sara , Wells Leslie , Ballou Jonathan D. , Fagan William F.
Published: June 2010

For species of conservation concern, ecologists often need to estimate potential population growth rates with minimal life history data. We use a survivorship database for captive mammals to show that, although survivorship scale (i.e., longevity) varies widely across mammals, survivorship shape (i.e., the age‐specific pattern of mortality once survivorship has been scaled to maximum longevity) varies little. Consequently, reasonable estimates of population growth rate can be achieved for diverse taxa using a model of survivorship shape along with an estimate of longevity. In addition, we find that the parameters of survivorship shape are related to taxonomic group, a fact that may be used to further improve estimates of survivorship when full life history data are unavailable. Finally, we compare survivorship shape in captive and wild populations of the same species and find higher adult survivorship in captive populations but no corresponding increase in juvenile survivorship. These differences likely reflect a convolution of true differences in captive vs. wild survivorship and the difficulty of observing juvenile mortality in field studies.
Decomposition of trait diversity among the nodes of a phylogenetic tree
Authors: Pavoine Sandrine , Baguette Michel , Bonsall Michael B.
Published: June 2010

Biodiversity studies aim to explain spatiotemporal patterns of species distributions. We propose a new methodology in which trait diversity is measured by the quadratic entropy index, with distances among species calculated from differences among trait states. We show how this index of trait diversity can be decomposed among the nodes of a phylogenetic tree. The contribution to trait diversity of a particular node is equal to the trait diversity among thengroups of species descending from it multiplied by an abundance weight (either proportional to the number of descendant species or to their relative abundance). We developed three tests to characterize the phylogenetic pattern of trait diversity and evaluated our methodology with seven evolutionary models. The power of the tests was high and increased with the number of extant taxa and the number of traits analyzed. The Type I error analyses (erroneous rejection of true null hypotheses) suggested that our tests are neither too liberal nor too conservative. Species abundances were found to modify the phylogenetic signal in trait diversity if only a few species were abundant and if species abundances were correlated to their phylogenetic relatedness and/or their trait states. By comparing phylogenetic signals in trait diversity from the local to the metacommunity level, we explored the factors that structure butterfly trait diversity in calcareous grasslands of northern France and southern Belgium. We show that partial phylogenetic signal in traits combined with habitat filtering determined which species and lineages were able to co‐occur locally. Interestingly, no phylogenetic signal was detected when measures of abundance were included in our analyses. For most species and clades, the abundance distribution among communities at the regional scale was random. Overall, studying trait diversity in a phylogenetic context allows the link between current local ecological processes and lineage‐dependent historical evolutionary factors to be thoroughly investigated.
A general hypothesis‐testing framework for stable isotope ratios in ecological studies
Authors: Turner Thomas F. , Collyer Michael L. , Krabbenhoft Trevor J.
Published: June 2010

We propose a framework for hypothesis‐testing of stable isotope ratios in ecological studies. Statistical procedures are based on analysis of nested linear models and a residual permutation procedure (RPP) that is employed to evaluate probabilities associated with test statistics. We used simulated examples and a real data set to illustrate the utility and generality of the method. First, we developed a test for differences in centroid location and dispersion of δ13C and δ15N values within and among groups of isotopic data. Second, we evaluated magnitude and direction of change in centroid position (termed “path”) of a pair of isotopic samples separated in space/time relative to paths of other paired sample sets. Third, we compared attributes of path trajectories (size, direction, and shape) over sample sets containing more than two samples to provide a quantitative description of how patterns of isotopic ratios change in response to spatial and temporal gradients. Examples are limited to the bivariate case (δ13C–δ15N biplots), but the statistical method can readily be applied to univariate and multivariate cases.
Studying dispersal at the landscape scale: efficient combination of population surveys and capture–recapture data
Authors: Péron Guillaume , Crochet Pierre-André , Doherty Paul F. , Lebreton Jean-Dominique
Published: June 2010

Researchers often rely on capture–mark–recapture (CMR) data to study animal dispersal in the wild. Yet their spatial coverage often does not encompass the entire dispersal range of the study individuals, sometimes producing misleading results. Information contained in population surveys and variation in population spatial structure can be used to overcome this issue. We build an integrated model in a multisite context in which CMR data are only collected at a subset of sites, but numbers of breeding pairs are counted at all sites. In a Black‐headed GullChroicocephalus ridibunduspopulation, the integrated‐modeling approach induces an increase in precision for the demographic parameters of interest (variances, on average, were decreased by 20%) and provides a more precise extrapolation of results from the CMR data to the whole population. Patterns of condition‐dependent dispersal are therefore made easier to detect, and we obtain evidence for colony‐size dependence in recruitment, dispersal, and breeding success. These results suggest that first‐time breeders disperse to small colonies in order to recruit earlier. The exchange of experienced breeders between colonies appears as a main determinant of the observed variation in colony sizes.
High‐dimensional coexistence based on individual variation: a synthesis of evidence
Authors: Clark James S. , Bell David , Chu Chengjin , Courbaud Benoit , Dietze Michael , Hersh Michelle , HilleRisLambers Janneke , Ibášez Inés , LaDeau Shannon , McMahon Sean , Metcalf Jessica , Mohan Jacqueline , Moran Emily , Pangle Luke , Pearson Scott , Salk Carl , Shen Zehao , Valle Denis , Wyckoff Peter
Published: June 2010

High biodiversity of forests is not predicted by traditional models, and evidence for trade‐offs those models require is limited. High‐dimensional regulation (e.g.,Nfactors to regulateNspecies) has long been recognized as a possible alternative explanation, but it has not be been seriously pursued, because only a few limiting resources are evident for trees, and analysis of multiple interactions is challenging. We develop a hierarchical model that allows us to synthesize data from long‐term, experimental, data sets with processes that control growth, maturation, fecundity, and survival. We allow for uncertainty at all stages and variation among 26 000 individuals and over time, including 268 000 tree years, for dozens of tree species. We estimate population‐level parameters that apply at the species level and the interactions among latent states, i.e., the demographic rates for each individual, every year. The former show that the traditional trade‐offs used to explain diversity are not present. Demographic rates overlap among species, and they do not show trends consistent with maintenance of diversity by simple mechanisms (negative correlations and limiting similarity). However, estimates of latent states at the level of individuals and years demonstrate that species partition environmental variation. Correlations between responses to variation in time are high for individuals of the same species, but not for individuals of different species. We demonstrate that these relationships are pervasive, providing strong evidence that high‐dimensional regulation is critical for biodiversity regulation.
Untangling positive and negative biotic interactions: views from above and below ground in a forest ecosystem
Authors: Montgomery Rebecca A. , Reich Peter B. , Palik Brian J.
Published: June 2010

In ecological communities, the outcome of plant–plant interactions represents the net effect of positive and negative interactions occurring above and below ground. Untangling these complex relationships can provide a better understanding of mechanisms that underlie plant–plant interactions and enhance our ability to predict population, community, and ecosystem effects of biotic interactions. In forested ecosystems, tree seedlings interact with established vegetation, but the mechanisms and outcomes of these interactions are not well understood. To explore such mechanisms, we manipulated above‐ and belowground interactions among tree seedlings, shrubs, and trees and monitored seedling survival and growth of six species (Pinus banksiana, Betula papyrifera, P. resinosa, Quercus rubra, P. strobus, and Acer rubrum) in mature pine‐dominated forest in northern Minnesota, USA. The forest had a moderately open canopy and sandy soils. Understory manipulations were implemented in the forest interior and in large gaps and included removal of shrubs (no interactions), tieback of shrubs (belowground), removal of shrubs with addition of shade (aboveground), and unmanipulated shrubs (both below‐ and aboveground). We found that shrubs either suppressed or facilitated seedling survival and growth depending on the seedling species, source of interaction (e.g., above‐ or belowground), and ecological context (e.g., gap or forest interior). In general, shrubs strongly influenced survival and growth in gaps, with more modest effects in the forest interior. In gaps, the presence of shrub roots markedly decreased seedling growth and survival, supporting the idea that belowground competition may be more important in dry, nutrient‐poor sites. Shrub shade effects were neutral for three species and facilitative for the other three. Facilitation was more likely for shade‐tolerant species. In the forest interior, shrub shade negatively affected seedling survival for the most shade‐intolerant species. For several species the net effect of shrubs masked the existence of both positive and negative interactions above and below ground. Our results highlight the complexity of plant–plant interactions, demonstrate that outcomes of these interactions vary with the nature of resource limitation and the ecophysiology of the species involved, and suggest that ecological theory that rests on particular notions of plant–plant interactions (e.g., competition) should consider simultaneous positive and negative interactions occurring above and below ground.
The enemy as ally: herbivore‐induced increase in crop yield
Authors: Poveda Katja , Jiménez María Isabel Gómez , Kessler André
Published: June 2010

There is increasing global concern over the risk of food shortage and instability, and a concomitant demand for an increase in food production. However, the continuing expansion of agricultural areas threatens natural habitats as well as human and ecosystem health. One option for increasing food production is to maximize yields from existing farmland. Here we demonstrate that larval feeding by the Guatemalan potato moth (Tecia solanivora), considered one of the most economically important potato pests in Latin America, leads to a dramatic increase in potato tuber production. Field‐grown potato plants (Solanum tuberosum) in the Colombian Andes attacked by low numbers of potato moth larvae produce a 2.5‐fold higher marketable potato yield than undamaged plants. Greenhouse experiments demonstrate that this effect is induced by larval regurgitant, rather than by mechanical tissue damage. Our results indicate that compounds from the foregut of T. solanivora are necessary and sufficient to induce an increased yield in potato. Our study suggests that using (1) herbivore‐derived chemical cues and (2) induced compensatory plant responses to herbivory can provide viable new tools to increase per area crop productivity.
Interacting regime shifts in ecosystems: implication for early warnings
Authors: Brock W. A. , Carpenter S. R.
Published: June 2010

Big ecological changes often involve regime shifts in which a critical threshold is crossed. Thresholds are often difficult to measure, and transgressions of thresholds come as surprises. If a critical threshold is approached gradually, however, there are early warnings of the impending regime shift. For example, in a one‐dimensional ecosystem dynamics, autocorrelation approaches 1 from below, variance and skewness increase, and variance spectra shift to lower frequencies. Here we focus on variance, an indicator easily computed from monitoring data.

There are two distinct sources of increased variance near a critical threshold. One is the amplification of small shocks that occurs as the square of the modulus of the leading eigenvalue (or leading pair of eigenvalues in the complex case) approaches 1 from below. This source, called “squealing,” is well‐studied. The second source of variance, called “flickering,” involves brief excursions between attractors.

Interacting regime shifts may muffle or magnify variance near critical thresholds. Whether muffling or magnification occurs, and the size of the effect, depend on the product of the feedback between the state variables times the correlation of these variables' responses to environmental shocks. If this product is positive, magnification of the variance will occur. If the product is negative, muffling or magnification can occur depending on the relative magnitudes of these and other effects. Therefore, monitoring programs should measure variates that have opposite responses to the critical transition. If the correlations to environmental shocks have the same sign, the variance of at least one variate will be magnified as the critical transition is approached.

Simulation studies suggest that muffling may sometimes interfere with detection of early warning signals of regime shifts. However, more important effects of muffling and magnification may come from their effect on flickering, when random shocks trigger a state change in a system with low resilience. Muffling decreases the likelihood that a random shock will trigger a regime shift. Magnification has the opposite effect. Magnification is most likely when feedbacks are positive and state variables have positively correlated responses to environmental shocks. These results help delimit the conditions when regime shifts are more likely to cascade through complex systems.
Reconciling contradictory findings of herbivore impacts on spotted knapweed (Centaurea stoebe) growth and reproduction
Authors: Knochel David G. , Seastedt Timothy R.
Published: June 2010

Substantial controversy surrounds the efficacy of biological control insects to reduce densities of Centaurea stoebe, a widespread, aggressive invasive plant in North America. We developed a graphical model to conceptualize the conditions required to explain the current contradictory findings, and then employed a series of manipulations to evaluate C. stoebe responses to herbivores. We manipulated soil nitrogen and competition in a field population and measured attack rates of a foliage and seed feeder (Larinus minutus), two gall flies (Urophora spp.), and a root feeder (Cyphocleonus achates), as well as their effects on the growth and reproduction of C. stoebe. Nitrogen limitation and competing vegetation greatly reduced C. stoebe growth. L. minutus most intensively reduced seed production in low‐nitrogen soils, and removal of neighboring vegetation increased Larinus numbers per flower head and the percentage of flowers attacked by 15% and 11%, respectively. Cyphocleonus reduced flower production and aboveground biomass over two years, regardless of resources or competition. Our results, in conjunction with other published studies, demonstrate that positive, neutral, and negative plant growth responses to herbivory can be generated. However, under realistic field conditions and in the presence of multiple herbivores, our work repudiates earlier studies that indicate insect herbivores increase C. stoebe dominance.
Hygroscopic particles on leaves: nutrients or desiccants?
Authors: Burkhardt Juergen
Published: June 2010

Aerosols have always been part of the atmosphere, and plant surfaces are a major aerosol sink. Given the nutrient content of aerosols and the natural stability of aerosol concentrations over evolutionary time, plants may have developed adaptations to aerosol input. Although little is known about such adaptations, leaf surface micro‐roughness appears to play a key role.

This review focuses on the deposition and fate of fine aerosols that are less than 2.5 μm in diameter. Most of these aerosols are hygroscopic, and they are often deliquescent (liquid) on transpiring leaves. Such concentrated solutions may be taken up by both the cuticle and stomata, contradicting previous concepts. The establishment of a continuous liquid water connection along stomatal walls affects individual stomata and is a new concept called “hydraulic activation of stomata” (HAS). HAS enables the efficient bidirectional transport of water and solutes between the leaf interior and leaf surface and makes stomatal transpiration partly independent of stomatal aperture. The response of plants to changes in humidity can be explained by the split transpiration in an HAS pore and its interaction with neighboring stomata, i.e., as an emergent property of a stomatal patch. Normally, HAS affects only a few stomata, but if too many are activated by excessive particle accumulation or additional surfactants, hygroscopic particles may work as “desiccants,” reducing the drought tolerance of plants. This is made use of when hygroscopic salts and acids are sprayed to kill potato vine, but may cause problems in foliar fertilization. Excessive particle accumulation may also be caused by air pollution. It is hypothesized that deliquescent hygroscopic particles, due to their amorphous appearance, may have been misinterpreted as “degraded waxes.” Degraded waxes have been highly correlated to leaf loss, decreased drought tolerance, and decreased frost tolerance of trees. No sound explanation for degraded waxes has been found, and they have been interpreted as symptoms of forest decline. Because hygroscopic particles may affect the drought tolerance of trees, they could be drivers of regional tree die‐off and especially affect those trees that have adapted to capture aerosols. Several research questions are identified.
Divergent composition but similar function of soil food webs of individual plants: plant species and community effects
Authors: Bezemer T. M. , Fountain M. T. , Barea J. M. , Christensen S. , Dekker S. C. , Duyts H. , van Hal R. , Harvey J. A. , Hedlund K. , Maraun M. , Mikola J. , Mladenov A. G. , Robin C. , de Ruiter P. C. , Scheu S. , Setälä H. , Šmilauer P. , van der Putten W. H.
Published: June 2010

Soils are extremely rich in biodiversity, and soil organisms play pivotal roles in supporting terrestrial life, but the role that individual plants and plant communities play in influencing the diversity and functioning of soil food webs remains highly debated. Plants, as primary producers and providers of resources to the soil food web, are of vital importance for the composition, structure, and functioning of soil communities. However, whether natural soil food webs that are completely open to immigration and emigration differ underneath individual plants remains unknown. In a biodiversity restoration experiment we first compared the soil nematode communities of 228 individual plants belonging to eight herbaceous species. We included grass, leguminous, and non‐leguminous species. Each individual plant grew intermingled with other species, but all plant species had a different nematode community. Moreover, nematode communities were more similar when plant individuals were growing in the same as compared to different plant communities, and these effects were most apparent for the groups of bacterivorous, carnivorous, and omnivorous nematodes. Subsequently, we analyzed the composition, structure, and functioning of the complete soil food webs of 58 individual plants, belonging to two of the plant species,Lotus corniculatus(Fabaceae) andPlantago lanceolata(Plantaginaceae). We isolated and identified more than 150 taxa/groups of soil organisms. The soil community composition and structure of the entire food webs were influenced both by the species identity of the plant individual and the surrounding plant community. Unexpectedly, plant identity had the strongest effects on decomposing soil organisms, widely believed to be generalist feeders. In contrast, quantitative food web modeling showed that the composition of the plant community influenced nitrogen mineralization under individual plants, but that plant species identity did not affect nitrogen or carbon mineralization or food web stability. Hence, the composition and structure of entire soil food webs vary at the scale of individual plants and are strongly influenced by the species identity of the plant. However, the ecosystem functions these food webs provide are determined by the identity of the entire plant community.
Habitat selection and the perceptual trap
Authors: Patten Michael A. , Kelly Jeffrey F.
Published: June 2010

The concept of “ecological traps” was introduced over three decades ago. An ecological trap occurs when, by various mechanisms, low‐quality (yielding low fitness) habitat is more attractive than good habitat, thus coaxing individuals to settle there despite a resultant loss of fitness. Empirical work on such traps has increased dramatically in the past decade, but the converse—avoidance of high‐quality habitat because it is less attractive, what we term a “perceptual trap”—has remained largely unexplored. Even so, depending on conditions (growth rate, strength of habitat preference, and mortality rate), such perceptual traps can be more limiting than ecological traps to population persistence. An example from field experiments with the Lesser Prairie‐Chicken (Tympanuchus pallidicinctus) lends empirical support to the concept, and several other potential examples suggest that these traps are perhaps more prevalent than has been appreciated. Because demographic Allee effects are expected to prevent a population from growing sufficiently in a habitat that is avoided, a perceptual trap may persist even though fitness is high. Unlike an ecological trap, which may be negated by increasing habitat quality, biologists will be hard pressed to negate a perceptual trap, which will require determining which cues an animal uses to select high‐quality habitat and then devising a means of enhancing those cues so that an animal is lured into the habitat.
Interactions among temporal patterns determine the effects of multiple stressors
Authors: Molinos Jorge García , Donohue Ian
Published: June 2010

Recent research has revealed that one of the most important characteristics of both natural and anthropogenic disturbances is their temporal heterogeneity. However, little is known about the relative importance of interactions among temporal patterns of multiple stressors. We established a fully factorial field experiment to test whether interactions among temporal patterns of two globally important anthropogenic disturbances of aquatic ecosystems (increased sediment loading and nutrient enrichment) determined the responses of stream benthic assemblages. Each disturbance treatment comprised three distinct regimes: regular and temporally variable pulses and an undisturbed control. The overall frequency, intensity and extent of disturbance was, however, equal across all disturbed treatments. We found that interactions among temporal disturbance regimes determined the effects of the compounded sediment and nutrient perturbations on algal biomass and the diversity, taxonomic and trophic composition of benthic assemblages. Moreover, our results also show that the temporal synchronization of multiple stressors does not necessarily maximize the impact of compounded perturbations. This comprises the first experimental evidence that interactions among the temporal patterns of disturbances drive the responses of ecosystems to multiple stressors. Knowledge of the temporal pattern of disturbances is therefore essential for the reliable prediction of impacts from, and effective management of, compounded perturbations.
Reef size and isolation determine the temporal stability of coral reef fish populations
Authors: Mellin Camille , Huchery Cindy , Caley M. Julian , Meekan Mark G. , Bradshaw Corey J. A.
Published: June 2010

Temporal variance in species abundance, a potential driver of extinction, is linked to mean abundance through Taylor's power law, the empirical observation of a linear log–log relationship with a slope between 1 and 2 for most species. Here we test the idea that the slope of Taylor's power law can vary both among species and spatially as a function of habitat area and isolation. We used the world's most extensive database of coral reef fish communities comprising a 15‐year series of fish abundances on 43 reefs of Australia's Great Barrier Reef. Greater temporal variances were observed at small and isolated reefs, and lower variances at large and connected ones. The combination of reef area and isolation was associated with an even greater effect on temporal variances, indicating strong empirical support for the idea that populations on small and isolated reefs will succumb more frequently to local extinction via higher temporal variability, resulting in lower resilience at the community level. Based on these relationships, we constructed a regional predictive map of the dynamic fragility of coral reef fish assemblages on the Great Barrier Reef.
Does pyrogenicity protect burning plants?
Authors: Gagnon Paul R. , Passmore Heather A. , Platt William J. , Myers Jonathan A. , Paine C. E. Timothy , Harms Kyle E.
Published: June 2010

Pyrogenic plants dominate many fire‐prone ecosystems. Their prevalence suggests some advantage to their enhanced flammability, but researchers have had difficulty tying pyrogenicity to individual‐level advantages. Based on our review, we propose that enhanced flammability in fire‐prone ecosystems should protect the belowground organs and nearby propagules of certain individual plants during fires. We base this hypothesis on five points: (1) organs and propagules by which many fire‐adapted plants survive fires are vulnerable to elevated soil temperatures during fires; (2) the degree to which burning plant fuels heat the soil depends mainly on residence times of fires and on fuel location relative to the soil; (3) fires and fire effects are locally heterogeneous, meaning that individual plants can affect local soil heating via their fuels; (4) how a plant burns can thus affect its fitness; and (5) in many cases, natural selection in fire‐prone habitats should therefore favor plants that burn rapidly and retain fuels off the ground. We predict an advantage of enhanced flammability for plants whose fuels influence local fire characteristics and whose regenerative tissues or propagules are affected by local variation in fires. Our “pyrogenicity as protection” hypothesis has the potential to apply to a range of life histories. We discuss implications for ecological and evolutionary theory and suggest considerations for testing the hypothesis.
Neighborhood phylodiversity affects plant performance
Authors: Castillo Juan Pablo , Verdú Miguel , Valiente-Banuet Alfonso
Published: June 2010

Facilitation and competition are ecological interactions that are crucial for the organization of plant communities. Facilitative interactions tend to occur among distantly related species, while the strength of competition tends to decrease with phylogenetic distance. The balance between both types of interactions will ultimately determine the specific composition of multispecies associations. Although multispecies patches are the arena in which coexistence develops among different phylogenetic groups within communities, the specific processes that occur across life stages have not been explored. Here we study how different species, in composing discrete patches in central Mexico, exert competitive or facilitative effects on seeds and seedlings. We relate these interactions to phylogenetic relationships among nurse species and beneficiary species, and among members of the patches. Survivorship and growth rates of the columnar cactus Neobuxbaumia mezcalaensis were highly positively related to increasing phylogenetic distance to different nurse species, to the presence of related species in patches, and to mean phylogenetic distances to the rest of the species in the patch. Each of these three elements influenced N. mezcalaensis differently, with different nurse species varying substantially in their early effects on emergence, and the nearest relatives and species composition of patches varying in their late effects on survival and growth. Our results emphasize that evolutionary relationships among co‐occurring species in vegetation clumps exert direct and indirect effects on plants, affecting individual performance and species coexistence.
Emotionality of Loss-Related Memories Is Reduced After Recall Plus Eye Movements But Not After Recall Plus Music or Recall Only
Authors: Hornsveld Hellen K. , Landwehr Frieda , Stein Willeke , Stomp Margaretha P. H. , Smeets Monique A. M. , van den Hout Marcel A.
Published: June 2010

Numerous studies have shown that eye movements during recall of negative memories reduce their emotionality. We investigated whether these findings can be extended specifically to negative memories of loss. Sixty undergraduate students participated and recalled a negative autobiographical memory of loss and performed—in counterbalanced order—three types of tasks: recall-plus-eye-movements, recall-only, and recall-plus-relaxing-music. Recall-plus-music was added to investigate whether reductions in emotionality are associated with relaxation. Levels of emotionality, relaxation, and concentration were assessed before and after each stimulus condition. Participants reported a greater decline in emotionality and concentration after eye movements in comparison to recall-only and recall-with-music. It is concluded that eye movements are effective when negative memories pertain to loss and grief, suggesting possibilities for treatment intervention in individuals suffering from complicated grief.
Rupture and Repair in the EMDR Client/Clinician Relationship: Now Moments and Moments of Meeting
Authors: Dworkin Mark , Errebo Nancy
Published: June 2010

This article proposes that eye movement desensitization and reprocessing (EMDR) would be strengthened by being conceptualized as a two-person therapy; that is, a therapy that employs dialogue between clinician and client about the resonance, attunement, and intention of their relationship. Current research on the mirror neuron system provides a hypothetical neurological underpinning to this proposal. Detailed clinical examples illustrate rupture (Now Moments) and subsequent repair (Moments of Meeting) of the therapeutic relationship in the Eight Phases of EMDR. The high potential for relationship rupture during EMDR therapy is discussed. Suggestions are made for improving EMDR practice, training, and consultation by attending to the intersubjective experience between client and clinician, especially when working with clients who have experienced repeated and pervasive disappointments in love and work.
Using EMDR With Survivors of Sexual Abuse Perpetrated by Roman Catholic Priests
Authors: Farrell Derek , Dworkin Mark , Keenan Paul , Spierings Joany
Published: June 2010

This article reviews research that investigated the idiosyncratic effects of sexual abuse perpetrated by Roman Catholic priests and makes related treatment recommendations. The research determined that this distinct form of sexual trauma generated unique posttraumatic symptoms not accounted for within the existing Posttraumatic Stress Disorder conceptual frameworks. These included significant anxiety and distress in areas such as theological belief, crisis of faith, and fears surrounding the participant’s own mortality. This article makes recommendations about EMDR treatment with clergy abuse survivors, based on these research findings utilizing a survivor’s story to illustrate case formulation and the utilization of process and content cognitive interweaves in addressing episodes of blocked processing.
e-Ana and e-Mia: A Content Analysis of Pro–Eating Disorder Web Sites
Authors: Borzekowski Dina L. G. , Schenk Summer , Wilson Jenny L. , Peebles Rebecka
Published: June 2010

Objectives. The Internet offers Web sites that describe, endorse, and support eating disorders. We examined the features of pro–eating disorder Web sites and the messages to which users may be exposed.

Methods. We conducted a systematic content analysis of 180 active Web sites, noting site logistics, site accessories, “thinspiration” material (images and prose intended to inspire weight loss), tips and tricks, recovery, themes, and perceived harm.

Results. Practically all (91%) of the Web sites were open to the public, and most (79%) had interactive features. A large majority (84%) offered pro-anorexia content, and 64% provided pro-bulimia content. Few sites focused on eating disorders as a lifestyle choice. Thinspiration material appeared on 85% of the sites, and 83% provided overt suggestions on how to engage in eating-disordered behaviors. Thirty-eight percent of the sites included recovery-oriented information or links. Common themes were success, control, perfection, and solidarity.

Conclusions. Pro–eating disorder Web sites present graphic material to encourage, support, and motivate site users to continue their efforts with anorexia and bulimia. Continued monitoring will offer a valuable foundation to build a better understanding of the effects of these sites on their users.