bluuebunny/crossref_metadata_2025_split huggingface dataset:
Disentangling the effects of multiple anthropogenic drivers on the decline of two tropical dry forest trees
Authors: Ticktin Tamara , Ganesan Rengaian , Paramesha Mallegowda , Setty Siddappa 
Published: October 2012

Summary1. Tropical plant populations are often subject to multiple types of anthropogenic disturbance. Effective management requires disentangling the effects of these disturbances and prioritizing interventions for the driver(s) most responsible for population decline. However, the effects of multiple drivers on plant population dynamics are rarely examined.2. We assessed the independent and combined effects of common anthropogenic disturbances on the transient and long‐term population dynamics of two economically important, declining tree species in an Indian dry forest. Specifically, we drew on 10 years of demographic monitoring to assess the effects of non‐timber forest product (NTFP) harvest and two invasive species (an understorey shrub Lantana camara and a mistletoe Taxillus tomentosus) on amla (Phyllanthus emblica and Phyllanthus indofischeri) populations.3. Although fruit harvest has been blamed for declining amla populations, the current policy and management strategies implemented to restrict it have little effect on long‐term stochastic growth rates (λs) of amla both with and without invasive species. In contrast, mistletoes significantly decreased λs of both species.4. Lantana had both direct and indirect effects on P. emblica, causing a regeneration bottleneck. Lantana had a direct negative effect on seeding and sapling growth, whereas populations without lantana experienced higher levels of grazing by wild animals. Over 10 years, P. emblica populations dropped to 16% of their original size in areas with invasive species.5. Synthesis and applications. Our results illustrate that mistletoe and lantana, not fruit harvest, are the main drivers of amla decline, and these species are likely to be driving the decline of other Indian dry forest tree species. Management directed only at limiting fruit harvest will be ineffective. Instead, control of both invasive species combined with temporary protection from grazing is urgently needed. The ban on fruit harvest in Indian protected areas is not an effective conservation policy for these species. Harvest is not necessarily the main cause of decline for NTFP species. Management plans for NTFP and other at‐risk species must consider the relative effects of different drivers of decline, including direct and indirect effects of invasive species.
Landscape‐scale responses of birds to agri‐environment management: a test of the English Environmental Stewardship scheme
Authors: Baker David J. , Freeman Stephen N. , Grice Phil V. , Siriwardena Gavin M. 
Published: October 2012

Summary1. Agri‐environment schemes (AES) are used extensively across Europe to address biodiversity declines in farmland. In England, Environmental Stewardship (ES) was introduced in 2005 to address the shortcomings of previous schemes, but as for schemes in other countries, assessments to date have revealed little evidence for national‐scale biodiversity benefits.2. Here, we assess the efficacy of ES in driving changes in national farmland bird populations over the period 2002–2010, using BTO/JNCC/RSPB Breeding Bird Survey data. We tested for associations between ES management options, grouped into categories reflecting intended biological effects (e.g. stubble), and species’ population growth rates, wherever benefits of management might be expected to occur.3. We found strong evidence for positive effects of management that provides winter food resources (i.e. ES stubble and wild bird seed [WBS] crops) on population growth rates across multiple granivorous species, at three landscape scales. The results for management aiming to provide breeding season benefits (i.e. grassland, field margin and boundary [hedge, ditch] management) showed mixed patterns of positive and negative associations.4. The results for stubble and WBS provide the first evidence for landscape‐scale responses of biodiversity to AES management. The negative relationships identified may also show the importance of management context driving unforeseen predation or competition effects.5. Synthesis and Applications. This study demonstrates that agri‐environment scheme management has the potential to have national‐scale effects on avian population growth rates, although our results suggest that some components of the scheme have had little effect on bird populations. Therefore, whilst this study provides the first proof‐of‐concept for broad‐and‐shallow scheme impacts on biodiversity, our results underline the importance of targeting towards population‐limiting factors, here winter food resources. A combination of low uptake of key in‐field options that provide winter seed and a failure to cover the late‐winter period effectively explains the lack of national population responses. Such issues need to be addressed before schemes like Environmental Stewardship will achieve their goals. This study shows the value of feedback from monitoring for informing scheme design, through identifying problems and testing solutions.
Macroinvertebrate responses along broad stressor gradients of deposited fine sediment and dissolved nutrients: a stream mesocosm experiment
Authors: Wagenhoff Annika , Townsend Colin R. , Matthaei Christoph D. 
Published: October 2012

Summary1. Degradation of freshwater ecosystems is a major concern worldwide. Agriculture introduces multiple stressors to streams, presenting a challenge for freshwater managers who must understand the relative strengths of individual stressor effects and their combined multiple‐stressor effects.2. Using a replicated regression design, we manipulated levels of fine sediment and nutrients to create a broad eight‐point gradient for each stressor across 128 stream mesocosms to determine the shapes of macroinvertebrate responses after 21 days of exposure.3. Subsidy–stress response patterns occurred along both stressor gradients. Sediment addition provided an initial subsidy for some pollution‐tolerant taxa and total macroinvertebrate density, but produced consistently negative effects for other taxa, total taxon richness and the density and richness of pollution‐sensitive Ephemeroptera, Plecoptera, Trichoptera (EPT) taxa. Nutrient enrichment provided an initial subsidy for densities of two common EPT taxa, total EPT density, macroinvertebrate and EPT taxon richness.4. Few macroinvertebrate variables were affected by a single stressor (always fine sediment). The majority of responses were additive multiple‐stressor patterns, although Chironomidae density and EPT taxon richness followed complex synergistic patterns.5. Fine sediment was a much more pervasive stressor than augmented nutrient concentrations. Overall, macroinvertebrate traits responded to stressors as strongly as community variables or individual taxa.6. Synthesis and applications. Managing both fine sediment and nutrient inputs from agriculture is crucial to achieve good stream condition but priority should be given to minimizing fine sediment, which should be maintained below a threshold of 5% cover and 0·5‐mm depth. Managers also need to be wary of interactive multiple‐stressor effects because ecological outcomes of an increase in stressor load may be worse than predicted based on the knowledge of single‐stressor effects.
Exploiting avian vision with aircraft lighting to reduce bird strikes
Authors: Blackwell Bradley F. , DeVault Travis L. , Seamans Thomas W. , Lima Steven L. , Baumhardt Patrice , Fernández‐Juricic Esteban 
Published: October 2012

Summary1. Bird–aircraft collisions (bird strikes) represent a substantial safety concern and financial burden to civil aviation world‐wide. Despite an increase in the rate of damaging bird strikes, necessary steps to develop a mitigation method outside of the airport environment have not been empirically tested.2. We assessed whether use of aircraft lighting might enhance detection of and reaction to the approach of an aircraft in flight by Canada geese Branta canadensis Linnaeus, a species responsible for a high rate of damaging bird strikes. We used a novel approach by estimating the visibility to the goose visual system of a standard radio‐controlled (RC) aircraft (standard aircraft) exhibiting either a 2‐Hz alternating pulse of two lights, or lights off; and another RC aircraft designed to mimic a raptor (predator model). We then exposed wing‐clipped Canada geese to the approach of each aircraft and quantified behavioural responses to respective treatments.3. Estimates of chromatic and achromatic contrasts indicated that the standard aircraft with lights on was more salient to the visual system of the Canada goose than with lights off or the predator model.4. At individual and group levels, quicker alert responses were observed to the standard aircraft with lights compared with the lights off and predator model. Goose groups showed similar responses to approaches by the standard aircraft and the predator model, suggesting use of antipredator behaviour to avoid the aircraft.5. Synthesis and applications. Understanding animal sensory ecology and associated behaviours can aid the development of methods exploiting certain behaviours to reduce negative human–wildlife interactions. For example, reducing the frequency of bird strikes requires the integration of wildlife management efforts within and outside of the airport environment that target species resource use and response to disturbance, with mitigation techniques focused on the aircraft. Moreover, the design of aircraft lighting systems to enhance detection and avoidance by birds is contingent upon understanding avian visual ecology and behaviour. Based on spectral sensitivity in Canada geese, aircraft‐mounted lights that peak in the ultraviolet/violet range (380–400 nm) are likely to produce the maximal behavioural effect.
Spatial heterogeneity across five rangelands managed with pyric‐herbivory
Authors: McGranahan Devan A. , Engle David M. , Fuhlendorf Samuel D. , Winter Stephen J. , Miller James R. , Debinski Diane M. 
Published: October 2012

Summary1. Many rangelands evolved under an interactive disturbance regime in which grazers respond to the spatial pattern of fire and create a patchy, heterogeneous landscape. Spatially heterogeneous fire and grazing create heterogeneity in vegetation structure at the landscape level (patch contrast) and increase rangeland biodiversity. We analysed five experiments comparing spatially heterogeneous fire treatments to spatially homogeneous fire treatments on grazed rangeland along a precipitation gradient in the North American Great Plains.2. We predicted that, across the precipitation gradient, management for heterogeneity increases both patch contrast and variance in the composition of plant functional groups. Furthermore, we predicted that patch contrast is positively correlated with variance in plant functional group composition. Because fire spread is important to the fire–grazing interaction, we discuss factors that reduce fire spread and reduce patch contrast despite management for heterogeneity.3. We compared patch contrast across pastures managed for heterogeneity and pastures managed for homogeneity with a linear mixed effect (LME) regression model. We used the LME model to partition variation in vegetation structure to each sampled scale so that a higher proportion of variation at the patch scale among pastures managed for heterogeneity indicates patch contrast. To examine the relationship between vegetation structure and plant community composition, we used constrained ordination to measure variation in functional group composition along the vegetation structure gradient. We used the meta‐analytical statistic, Cohen’s d, to compare effect sizes for patch contrast and plant functional group composition.4. Management for heterogeneity increased patch contrast and increased the range of plant functional group composition at three of the five experimental locations.5. Plant functional group composition varied in proportion to the amount of spatial heterogeneity in vegetation structure on pastures managed for heterogeneity.6. Synthesis and applications. Pyric‐herbivory management for heterogeneity created patch contrast in vegetation across a broad range of precipitation and plant community types, provided that fire was the primary driver of grazer site selection. Management for heterogeneity did not universally create patch contrast. Stocking rate and invasive plant species are key regulators of heterogeneity, as they determine the influence of fire on the spatial pattern of fuel, vegetation structure and herbivore patch selection, and therefore also require careful management.
Genotypically diverse cultivar mixtures for insect pest management and increased crop yields
Authors: Tooker John F. , Frank Steven D. 
Published: October 2012

Summary
In modern crop production, each plant is often nearly genetically identical to its neighbours, allowing insect pests and pathogens to move easily from plant to plant and decimate crop fields. The associational resistance and enemies hypotheses predict that increasing plant diversity in agricultural fields will reduce pest abundance and damage. Ample research has supported these hypotheses by demonstrating that increased plant species diversity can improve insect pest management via bottom–up and top–down mechanisms. In spite of this support, diversification strategies that might contribute to improved pest control and yield have not been widely adopted owing to logistical and financial constraints.
Basic and applied research is increasingly demonstrating the value of intraspecific genetic diversity for improving ecosystem stability and function. Thus, a more practical way of diversifying crop fields may be to increase plant genotypic diversity by planting cultivar mixtures. Our objective is to review the literature documenting the benefits of genotypic diversity for natural and agricultural ecosystems and synthesize the evidence in support of intraspecific diversity as a viable pest management strategy for insect pests of field crops. We found strong support for wide‐ranging benefits of genotypic diversity that improved plant fitness and productivity in natural and applied settings.
Multiple lines of evidence converge to support the potential of intraspecific variation to contribute to improve insect pest control. However, very little work has sought to develop empirical support or viable implementation practices in agricultural systems. Thus, implementation of this practice is limited.
Synthesis and applications. Intraspecific plant diversity can improve plant fitness via bottom–up and top–down effects on pest populations and niche partitioning. Further research is required to refine implementation practices and demonstrate value in terms of reduced pesticide use and increased yield. Growers can implement intraspecific crop diversity with minimal financial investment or changes in production practices. As the benefits of biodiversity for yield stability are increasingly recognized, intraspecific diversity is poised to become a prominent and sustainable management tactic.
Plant traits predict the success of weed biocontrol
Authors: Paynter Quentin , Overton Jacob McC. , Hill Richard L. , Bellgard Stanley E. , Dawson Murray I. 
Published: October 2012

Summary
Biological control (biocontrol) can provide permanent cost‐effective control of plant pests, but has variable success. The ability to predict the success of weed biocontrol should improve target prioritisation and the cost‐benefit ratio of weed biocontrol.
We compiled a data base of the quantitative impacts of weed biocontrol programmes against 80 weed species and tested hypotheses regarding weed traits that contribute to weed biocontrol success using generalised additive models.
Modelling and cross‐validation indicated that a model with three traits provided good ability to predict the responses of novel species in novel regions. Biocontrol impact varied according to whether a weed was reported to be a major weed in its native range, mode of reproduction (sexual or asexual) and ecosystem (aquatic or wetland versus terrestrial).
Biocontrol appears to be highly effective against weeds with the best combination of factors for success (aquatic, asexual species that are not major weeds in their native ranges), whereas most, but not all, programmes against ‘difficult targets’, which possess the worst combination of factors for success, have failed to result in a substantial impact. An additional analysis provides a preliminary indication that the success of pioneering programmes predicts the success of repeat programmes against the same target weed in other regions.
Synthesis and applications. Predictions generated by our model will assist weed prioritisation by improving the ability to predict the success of weed biocontrol. Nevertheless, prioritisation must also consider the importance of the candidate target weeds. Species that are predicted to be difficult targets could be targeted for biocontrol, provided that they are sufficiently important to offset the increased risk of failure against the greater benefits of successful control. Further investigation is needed to assess the ability of successful pioneering programmes to predict the success of repeat programmes in other locations, particularly in conjunction with plant traits.
Does environmental contamination influence egg coloration? A long‐term study in herring gulls
Authors: Hanley Daniel , Doucet Stéphanie M. 
Published: October 2012

SummaryAlthough considerable progress has been made in reducing concentrations of persistent organic compounds in the environment, these contaminants are still found in many taxa. Here, we investigate the relationship between environmental contamination and avian egg coloration to examine whether egg coloration could be used as a bioindicator of contaminant load.TheHerringGullMonitoringProgramme has documented changes in contaminant levels found in herring gullLarus argentatusPontoppidan eggs across the Great Lakes for nearly 40 years. We measured the coloration of these eggs using reflectance spectrophotometry and evaluated the influence of a suite of contaminants on egg colour using general linear mixed models.Herring gull egg coloration was related to the levels of environmental contaminants found within the eggs. Our findings reveal a negative association between blue‐green chroma and a principal component explaining contaminant load. We also found that ultraviolet chroma varied positively with contaminant load, whereas brown chroma was not significantly related to contaminant load. In addition, a cross‐validated discriminant function analysis was able to correctly classify 84% of eggs to either high or low contaminant load. This is an important first step in assessing the utility of using egg coloration as a proxy for contaminant load in a colonially breeding waterbird.Synthesis and applications. Our study utilized a large, multi‐year data set to provide the first evidence that a suite of environmental contaminants appear to influence avian eggshell coloration. We also found that objective spectrophotometric measurements provide a reliable tool for assessment of egg contaminant load, and we provide a discriminant function for contaminant classification directly in the field. Our findings should be broadly relevant, because the pigments responsible for avian egg coloration are shared across all birds. The application of eggshell colour as a bio‐monitoring tool has important conservation and management applications; measuring egg coloration may provide a rapid, inexpensive and nondestructive means of estimating contaminant levels in the environment. This may provide an essential tool for monitoring areas or species of concern, as well as evaluating potential human health risks, by identifying populations supported by an environment that requires more attention and potentially environmental remediation.
Local depletion by a fishery can affect seabird foraging
Authors: Bertrand Sophie , Joo Rocío , Arbulu Smet Claude , Tremblay Yann , Barbraud Christophe , Weimerskirch Henri 
Published: October 2012

SummaryLong‐term demographic studies show that seabird populations may suffer from competition with fisheries. Understanding this process is critical for the implementation of an ecosystem approach to fisheries management (EAF). Existing studies rely mostly on indirect clues: overlaps between seabird foraging and fishing areas, comparing fish catches by seabirds and vessels.The study is based on aGPStracking experiment performed in 2007 on one of the main guano‐producing seabird species, thePeruvian booby, breeding on an island near the major port for anchovy landings inPeru. The fishery, which is entirely monitored by aVesselMonitoringSystem, opened the day we began the tracking experiment, providing a unique opportunity to examine the day‐to‐day effects of an intense fishing activity on seabird foraging behaviour.We observed a significant increase in the range of the daily trips and distances of the dives by birds from the colony. This increase was significantly related to the concomitant fishing activity. Seabirds progressively became more segregated in space from the vessels. Their increased foraging effort was significantly related to the growing quantity of anchovy removals by the fishery. In addition, daily removals by the fishery were at least 100 times greater than the daily anchovy requirement of the seabird colonies. We conclude that seabirds needed to forage farther to cope with the regional prey depletion created by the intensive fishing behaviour of this open access fishery.Synthesis and applications. We show that the foraging efficiency of breeding seabirds may be significantly affected by not only the global quantity, but also the temporal and spatial patterns of fishery removals. Together with an ecosystem‐based definition of the fishery quota, anEAFshould limit the risk of local depletion around breeding colonies using, for instance, adaptive marine protected areas.