bluuebunny/crossref_metadata_2025_split huggingface dataset:
Standards for ecologically successful river restoration
Authors: PALMER M.A. , BERNHARDT E.S. , ALLAN J. D. , LAKE P.S. , ALEXANDER G. , BROOKS S. , CARR J. , CLAYTON S. , DAHM C. N. , FOLLSTAD SHAH J. , GALAT D. L. , LOSS S. G. , GOODWIN P. , HART D.D. , HASSETT B. , JENKINSON R. , KONDOLF G.M. , LAVE R. , MEYER J.L. , O'DONNELL T.K. , PAGANO L. , SUDDUTH E. 
Published: April 2005

Summary

Increasingly, river managers are turning from hard engineering solutions to ecologically based restoration activities in order to improve degraded waterways. River restoration projects aim to maintain or increase ecosystem goods and services while protecting downstream and coastal ecosystems. There is growing interest in applying river restoration techniques to solve environmental problems, yet little agreement exists on what constitutes a successful river restoration effort.
We propose five criteria for measuring success, with emphasis on an ecological perspective. First, the design of an ecological river restoration project should be based on a specified guiding image of a more dynamic, healthy river that could exist at the site. Secondly, the river's ecological condition must be measurably improved. Thirdly, the river system must be more self‐sustaining and resilient to external perturbations so that only minimal follow‐up maintenance is needed. Fourthly, during the construction phase, no lasting harm should be inflicted on the ecosystem. Fifthly, both pre‐ and post‐assessment must be completed and data made publicly available.
Determining if these five criteria have been met for a particular project requires development of an assessment protocol. We suggest standards of evaluation for each of the five criteria and provide examples of suitable indicators.
Synthesis and applications. Billions of dollars are currently spent restoring streams and rivers, yet to date there are no agreed upon standards for what constitutes ecologically beneficial stream and river restoration. We propose five criteria that must be met for a river restoration project to be considered ecologically successful. It is critical that the broad restoration community, including funding agencies, practitioners and citizen restoration groups, adopt criteria for defining and assessing ecological success in restoration. Standards are needed because progress in the science and practice of river restoration has been hampered by the lack of agreed upon criteria for judging ecological success. Without well‐accepted criteria that are ultimately supported by funding and implementing agencies, there is little incentive for practitioners to assess and report restoration outcomes. Improving methods and weighing the ecological benefits of various restoration approaches require organized national‐level reporting systems.
The effects of organic agriculture on biodiversity and abundance: a meta‐analysis
Authors: BENGTSSON JANNE , AHNSTRÖM JOHAN , WEIBULL ANN‐CHRISTIN 
Published: April 2005

SummaryThe efficiency of agricultural subsidy programmes for preserving biodiversity and improving the environment has been questioned in recent years. Organic farming operates without pesticides, herbicides and inorganic fertilizers, and usually with a more diverse crop rotation. It has been suggested that this system enhances biodiversity in agricultural landscapes. We analysed the effects of organic farming on species richness and abundance using meta‐analysis of literature published before December 2002.Organic farming usually increases species richness, having on average 30% higher species richness than conventional farming systems. However, the results were variable among studies, and 16% of them actually showed a negative effect of organic farming on species richness. We therefore divided the data into different organism groups and according to the spatial scale of the study.Birds, insects and plants usually showed an increased species richness in organic farming systems. However, the number of studies was low in most organism groups (range 2–19) and there was significant heterogeneity between studies. The effect of organic farming was largest in studies performed at the plot scale. In studies at the farm scale, when organic and conventional farms were matched according to landscape structure, the effect was significant but highly heterogeneous.On average, organisms were 50% more abundant in organic farming systems, but the results were highly variable between studies and organism groups. Birds, predatory insects, soil organisms and plants responded positively to organic farming, while non‐predatory insects and pests did not. The positive effects of organic farming on abundance were prominent at the plot and field scales, but not for farms in matched landscapes.Synthesis and applications.Our results show that organic farming often has positive effects on species richness and abundance, but that its effects are likely to differ between organism groups and landscapes. We suggest that positive effects of organic farming on species richness can be expected in intensively managed agricultural landscapes, but not in small‐scale landscapes comprising many other biotopes as well as agricultural fields. Measures to preserve and enhance biodiversity should be more landscape‐ and farm‐specific than is presently the case.
Effects of radio‐collar position and orientation on GPS radio‐collar performance, and the implications of PDOP in data screening
Authors: D'EON ROBERT G. , DELPARTE DONNA 
Published: April 2005

Summary

Global positioning system (GPS) radio‐telemetry has become an important wildlife research technique worldwide. However, understanding, quantifying and managing error and bias in raw GPS radio‐telemetry data sets requires much more work. In particular, error and bias resulting from position (angle away from vertical) and orientation (compass direction) of GPS radio‐collars on free‐ranging animals is currently unknown.
We tested the effects of collar position and orientation on GPS radio‐collar performance using five stationary GPS radio‐collars. We also investigated the use of positional dilution of precision (PDOP) as a method for screening data with high location errors.
Orientation had no statistical effect on fix rates or location errors. The biggest source of variation was attributed to collar position, which resulted in significantly lower performance at angles below 90° from vertical.
PDOP‐based screening was effective and can be used to lower location error, but the trade‐off between higher location accuracy and data loss (potentially leading to new bias) must be assessed.
Synthesis and applications. The results of this study refine our understanding of error and bias in GPS radio‐telemetry data. We suggest that collar orientation can safely be disregarded, whereas radio‐collar position remains a large potential source of error and bias. This finding has major implications regarding animal activity and GPS radio‐telemetry research. Researchers need to quantify and account for biases resulting from animals moving through heterogeneous terrain and habitats.
Effects of ski piste preparation on alpine vegetation
Authors: WIPF SONJA , RIXEN CHRISTIAN , FISCHER MARKUS , SCHMID BERNHARD , STOECKLI VERONIKA 
Published: April 2005

Summary

Ski resorts increasingly affect alpine ecosystems through enlargement of ski pistes, machine‐grading of ski piste areas and increasing use of artificial snow.
In 12 Swiss alpine ski resorts, we investigated the effects of ski piste management on vegetation structure and composition using a pairwise design of 38 plots on ski pistes and 38 adjacent plots off‐piste.
Plots on ski pistes had lower species richness and productivity, and lower abundance and cover of woody plants and early flowering species, than reference plots. Plots on machine‐graded pistes had higher indicator values for nutrients and light, and lower vegetation cover, productivity, species diversity and abundance of early flowering and woody plants. Time since machine‐grading did not mitigate the impacts of machine‐grading, even for those plots where revegetation had been attempted by sowing.
The longer artificial snow had been used on ski pistes (2–15 years), the higher the moisture and nutrient indicator values. Longer use also affected species composition by increasing the abundance of woody plants, snowbed species and late‐flowering species, and decreasing wind‐edge species.
Synthesis and applications. All types of ski piste management cause deviations from the natural structure and composition of alpine vegetation, and lead to lower plant species diversity. Machine‐grading causes particularly severe and lasting impacts on alpine vegetation, which are mitigated neither by time nor by revegetation measures. The impacts of artificial snow increase with the period of time since it was first applied to ski piste vegetation. Extensive machine‐grading and snow production should be avoided, especially in areas where nutrient and water input are a concern. Ski pistes should not be established in areas where the alpine vegetation has a high conservation value.
Land use and population growth of Primula veris: an experimental demographic approach
Authors: EHRLÉN JOHAN , SYRJÄNEN KIMMO , LEIMU ROOSA , BEGOÑA GARCIA MARIA , LEHTILÄ KARI 
Published: April 2005

Summary

Changes in land use are the primary cause of decline for many plant species. Efficient management actions for such species must be based on knowledge of the key phases of the plant life cycles that respond most to changes in environmental factors.
To assess how grazing influences population viability of the perennial rosette herb Primula veris, we applied four experimental treatments to abandoned grasslands and recorded the demographic response in permanent plots and seed sowing experiments over 3 years.
Treatments had strong effects on population viability. Transition matrix models showed that cutting the surrounding vegetation had no effect on population growth rate (λ). However, when this was combined with litter removal λ increased to 1·46, compared with 1·11 in controls. With disturbance and complete removal of the surrounding vegetation the effect was even stronger, and λ increased to 1·60.
Increases in λ were primarily a result of increased growth of the smallest rosettes, and increased seedling production. In contrast, the performance of larger P. veris individuals was not affected by experimental treatments.
The higher the elasticity of a particular life cycle transition, the less the change in the transition rate caused by treatments. This suggests that plants are able partly to buffer the effects of environmental variation by minimizing changes in the life cycle transitions that are most important to population growth rate.
Synthesis and applications. Experimental demographic approaches provide an important tool for assessing how grazing and other types of management influence species viability, and help to unravel the mechanisms underlying such relationships. With such information it is possible to predict the effects of novel types of management and land‐use scenarios on population viability. For P. veris, we identified seedling establishment as a key phase in the life cycle, and litter accumulation as a key environmental factor, suggesting that these should be prime targets for management. One practice that is likely to favour as well as seedling establishment preventing litter accumulation is late summer grazing.
Relative importance of burning, mowing and species translocation in the restoration of a former boreal hayfield: responses of plant diversity and the microbial community
Authors: ANTONSEN HILDE , OLSSON PÅL AXEL 
Published: April 2005

Summary

The extensive loss of species‐rich grasslands in Europe as a result of agricultural intensification has triggered a desire to recreate more diverse and natural grassland systems in set‐aside fields. Appropriate management and species introductions are necessary to overcome residual soil fertility, lack of suitable plant propagules and dominance of undesirable invasive species.
A field experiment was performed in a boreal former hayfield to test the effect of turf inoculation, mowing (twice annually) and spring burning. We surveyed changes in plant diversity, composition and productivity over a 3‐year period. Signature fatty acids and soil respiration measurements were employed to survey changes in the soil community.
Few changes in the vegetation and soil communities could be related to inoculation of turf monoliths. Most of the measured variables in mown plots differed from the set‐aside (control) plots, while burned plots displayed mainly similar responses. Mowing increased plant species richness and diversity, mainly by enhancing the number and frequency of forb species. Small‐statured forb species were promoted by mowing, whereas tall leafy grasses declined. Effects of mowing on soil communities comprised an increased soil respiration and stimulation of arbuscular mycorrhizal fungi.
Synthesis and applications. The results demonstrate the importance of reducing sward height in order to promote plant species coexistence in former boreal hayfields. In such systems, eliminating accumulated litter by spring burning has little influence on species composition when the sward is allowed to grow tall. Mowing is therefore the most efficient way of enhancing biodiversity. The results also show that mowing‐mediated changes in above‐ground plant communities may stimulate below‐ground symbiotic micro‐organisms, potentially resulting in a positive feedback on ecosystem development.
Life after logging: post‐logging recovery of a neotropical bat community
Authors: CLARKE F. M. , ROSTANT L. V. , RACEY P. A. 
Published: April 2005

Summary

There is considerable debate about whether tropical forests can be managed for timber production and to conserve biodiversity. Few ‘sustainable forestry’ systems have been evaluated adequately in this respect. Microchiropteran bats may be model taxa for this purpose. They are an important component of mammalian diversity, play key roles in forest dynamics and are indicators of disturbance in neotropical forests.
We investigated the effect of Trinidad's periodic block system (PBS) on bat species diversity and community organization. PBS is a polycyclic system of selective logging with a 30‐year harvesting rotation. We captured bats in primary forest and PBS‐managed forest logged 33, 31, 21, 20 and 10 years previously.
Selective logging did not affect species diversity but did affect community structure. Frugivorous bats were significantly more abundant in logged forest whereas gleaning animalivores were more abundant in primary forest, suggesting that frugivores benefited and gleaning animalivores were adversely affected by logging.
The bat community showed evidence of recovery. The number of years since forest disturbance was positively correlated with the abundance and number of species of gleaning animalivores and negatively correlated with the proportional abundance of the most common species. Gleaning animalivores increased in abundance with forest regeneration, whereas the community became less dominated by a single generalist frugivore.
Synthesis and applications. PBS selective logging appears to be compatible with the conservation of bat diversity. This provides evidence that neotropical forests can be managed for timber production in an ecologically sustainable way and that significant biodiversity conservation efforts can occur outside national parks and nature reserves in areas set aside for sustainable development. PBS could serve as a basic blueprint for sustainable forestry in the Guianan Shield where there are forests similar in species composition to those of Trinidad. Key attributes that could be adopted by many tropical countries to manage their forests in an ecologically sustainable way are a low intensity harvest, a long rotation and multiple controls on harvesting.
Molecular evidence for multiple introductions of garlic mustard (Alliaria petiolata, Brassicaceae) to North America
Authors: DURKA WALTER , BOSSDORF OLIVER , PRATI DANIEL , AUGE HARALD 
Published: April 2005

AbstractInvasive species offer excellent model systems for studying rapid evolutionary change. In this context, molecular markers play an important role because they provide information about pathways of introduction, the amount of genetic variation introduced, and the extent to which founder effects and inbreeding after population bottlenecks may have contributed to evolutionary change. Here, we studied microsatellite variation in eight polymorphic loci among and within 27 native and 26 introduced populations of garlic mustard (Alliaria petiolata), a European herb which is a current serious invader in North American deciduous forests. Overall, introduced populations were genetically less diverse. However, considerable variability was present and when compared to the probable source regions, no bottleneck was evident. Observed heterozygosity was very low and resulted in high inbreeding coefficients, which did not differ significantly between native and introduced populations. Thus, selfing seems to be equally dominant in both ranges. Consequently, there was strong population differentiation in the native (FST = 0.704) and the introduced (FST = 0.789) ranges. The high allelic diversity in the introduced range strongly suggests multiple introductions ofAlliaria petiolatato North America. Out of six European regions, the British Isles, northern Europe, and central Europe had significantly higher proportions of alleles, which are common to the introduced range, and are therefore the most probable source regions. The genetic diversity established by multiple introductions, and the lack of inbreeding depression in this highly selfing species, may have contributed to the invasion success ofAlliaria petiolata.
Maintenance of clonal diversity during a spring bloom of the centric diatom Ditylum brightwellii
Authors: RYNEARSON TATIANA A. , ARMBRUST E. VIRGINIA 
Published: April 2005

AbstractMaintenance of genetic diversity in eukaryotic microbes reflects a synergism between reproductive mode (asexual vs. sexual) and environmental conditions. We determined clonal diversity in field samples of the planktonic marine diatom, Ditylum brightwellii, during a bloom, when cell number increased by seven‐fold because of rapid asexual division. The genotypes at three microsatellite loci were determined for 607 individual cell lines isolated during the 11 days of sampling. Genetic diversity remained high during the bloom and 87% of the cells sampled each day were genetically distinct. Sixty‐nine clonal lineages were sampled two or more times during the bloom, and two clones were sampled seven times. Based on the frequency of resampled clonal lineages, capture–recapture statistics were used to determine that at least 2400 genetically distinct clonal lineages comprised the bloom population. No significant differences in microsatellite allele frequencies were observed among daily samples indicating that the bloom was comprised of a single population. No sexual stages were observed, although linkage equilibrium at two loci, high levels of allelic and genotypic diversity, and heterozygote deficiencies were all indicative of past sexual reproduction events. At the height of the bloom, a windstorm diluted cell numbers by 51% and coincided with a change in the frequency distribution of some resampled lineages. The extensive clonal diversity generated through past sexual reproduction events coupled with frequent environmental changes appear to prevent individual clonal lineages from becoming numerically dominant, maintaining genetic diversity and the adaptive potential of the population.
Inheritance of song and stridulatory peg number divergence between Chorthippus brunneus and C. jacobsi, two naturally hybridizing grasshopper species (Orthoptera: Acrididae)
Authors: SALDAMANDO C. I. , MIYAGUCHI S. , TATSUTA H. , KISHINO H. , BRIDLE J. R. , BUTLIN R. K. 
Published: April 2005

AbstractKnowledge of the genetic basis of divergence in mating signal characters that contribute to reproductive isolation is critical to understanding speciation. Here, we describe a semi‐automated system for characterizing grasshopper acoustic signals. We used this system to study the genetic basis of divergence in three male calling song components [echeme (EL), syllable (SL) and phrase (PL) lengths] between Chorthippus brunneus and C. jacobsi, two species of grasshoppers that hybridize in northern Spain. We also studied the number of pegs in the stridulatory file. For all characters, additive effects accounted for most of the genetic differentiation between species. However, the three song components also showed small but significant epistatic effects. No sex linkage was detected. Wright–Castle–Lande estimates of the minimum numbers of genetic factors underlying song and peg number divergence were low: peg number (ne = 5.87 ± 5.84), SL (ne = 2.37 ± 4.79) and PL (ne = 0.87 ± 0.86). On the other hand, EL appeared to be controlled by many genes. These results suggest that divergence in SL and PL might be driven by sexual selection whereas EL might not be under selection. This is consistent with experimental results on female song preference in related species. However, the fact that few factors appear to underlie the differences in peg number is surprising. Peg number is not closely related to song characteristics. It often varies between closely related grasshopper species and it has been assumed to be a neutral character. The biometrical approaches used here tend to underestimate the number of factors influencing a trait but provide valuable background for subsequent quantitative trait loci analyses.
Evolution of bite force in Darwin's finches: a key role for head width
Authors: HERREL A. , PODOS J. , HUBER S. K. , HENDRY A. P. 
Published: April 2005

AbstractStudies of Darwin's finches of the Galápagos Islands have provided pivotal insights into the interplay of ecological variation, natural selection, and morphological evolution. Here we document, across nine Darwin's finch species, correlations between morphological variation and bite force capacity. We find that bite force correlates strongly with beak depth and width but only weakly or not at all with beak length, a result that is consistent with prior demonstrations of natural selection on finch beak morphology. We also find that bite force is predicted even more strongly by head width, which exceeds all beak dimensions in predictive strength. To explain this result we suggest that head width determines the maximum size, and thus maximum force generation capacity of finch jaw adductor muscles. We suggest that head width is functionally relevant and may be a previously unrecognized locus of natural selection in these birds, because of its close relationship to bite force capacity.