140 research outputs found
When and where neonicotinoids are bad for bees
No full textThe so-far largest on field study reveals crucial insights on the use of neonicotinoids in agriculture. A lay summary of: Woodcock B, Bullock J, Shore R, Heard M, Pereira M, Redhead J, Ridding L, Dean H, Sleep D, Henrys P, Peyton J, Hulmes S, Hulmes L, Sárospataki M, Saure C, Edwards M, Genersch E, Knäbe S, Pywell R. Country-specific effects of neonicotinoid pesticides on honey bees and wild bees. Science. 2017;356(6345):1393-1395. doi:10.1126/science.aaa1190
Using functional traits to predict pollination services: A review
No full textPollination is a fundamental ecosystem service. Predictive and mechanistic models linking pollinator community structure to pollination services increasingly incorporate information on unique functional differences among species, so called effects traits. There is little consensus as to which traits are most important in supporting pollination services at either an individual or community level. Here, we synthesise the state of current knowledge regarding the role and efficacy of traits for predicting pollination, as well as the use of different methods for describing the trait structure of pollinator assemblages. We find a wide range of traits are currently used to predict pollination services, including morphological, behavioural and phenological characteristics. However, we show that the evidence demonstrating their importance is often limited or mixed. There is a trade-off in how traits are used between those that are easier to measure, available for many species but have only limited evidence for their role in pollination, vs. those that are harder to measure but with a more robust link with pollination service delivery. We highlight how community weighted means and measures of functional diversity offer important, albeit different insights into pollination service delivery. We discuss how their relative importance is likely to depend on the goals of the study. To maximise fully the utilisation of traits to predict pollination services, future research should be directed towards the widespread and consistent validation of the links among different traits and the pollination service across crop and semi-natural plant communities. Ideally this also needs to address geographical and taxonomic biases in trait collection
Seed bank dynamics in restored grassland following the sowing of high- and low-diversity seed mixtures
No full textSoil seed banks on ex-arable land are dominated by undesirable ruderal species that compete with “desirable” target species during grassland restoration. At the same time, for continued regeneration, the latter often functionally depend on gap colonization from the seed bank, which serves as a buffer against local extinction. Nonetheless, few studies have so far investigated the effects of restoration practices on seed bank dynamics. Using a multisite experiment investigating techniques for restoring lowland mesotrophic grassland, we studied the effects of seedbed preparation (shallow cultivation using harrows or discs vs. deep cultivation using a plow) and of seed mixtures (species-rich grass–forb mixes vs. species-poor grass-only mixes vs. unseeded natural regeneration) on 7 years of post-restoration seed bank dynamics. We assessed how these practices affected density and diversity of sown and unsown species in the seed bank. Seed bank dynamics were much more strongly affected by seed sowing than by cultivation. Grass sowing resulted in stronger seed bank decline of unsown grasses, and additional forb sowing in stronger decline of unsown forbs. Higher seed densities and species richness of sown forbs colonizing from neighboring plots sown with the grass–forb mix were observed under natural regeneration than in the grass-only sown treatment, reflecting grass priority effects on sown forb colonization in the latter. Sowing of diverse target species mixtures was associated with the greatest shift in seed bank composition away from extant ruderal species towards sown target species. Our results illustrate the usefulness of seed bank monitoring for assessing restoration progress
Testing the generality of hemiparasitic plant effects on mesotrophic grasslands: A multi-site experiment
No full textRestoration of species-rich, semi-natural grasslands is one of the key conservation challenges in Europe. Many of these
grasslands have lost their diversity due to agricultural intensification. A new tool to facilitate restoration is to introduce hemiparasitic
plants such as Rhinanthus species. R. minor accelerates restoration by decreasing the biomass of competitive plants and
creating gaps which benefit colonising species. Questions remain about the generality of these impacts and whether R. minor
can establish and facilitate community change in more productive grasslands. We addressed these questions by introducing
R. minor into 13 mesotrophic grassland sites in southern England. These represented four main soil types and different ages
of grasslands (eight permanent grasslands and five temporary ex-arable grasslands). We investigated two treatments using a
factorial design: +/− Rhinanthus seed addition and +/− soil surface scarification. Rhinanthus populations established at all but
one site. There was high variation in establishment success between the sites (range 0% to 25%), but productivity of the site or
nutrient level did not affect establishment. However, scarification improved establishment. Rhinanthus decreased host (mainly
grasses and legumes) biomass by between 27 and 37%. Scarification also decreased grass, legume, total and host biomass. There
was a strong negative relationship between the abundance of hemiparasites and grass biomass. Non-leguminous herbs were
not affected by the treatments, but grassland age had an effect as there were more herbs in permanent grasslands. The results
show that it is possible to establish Rhinanthus into different mesotrophic grassland communities representing a variety of soil
types and ages, suggesting it is a practical and widely applicable tool for restoration. The considerable variation in the rate of
Rhinanthus establishment is unexplained. The factors behind this variation may lie in unfavourable weather conditions during
germination and seedling stages, and herbivory
Grazing alters insect visitation networks and plant mating systems
No full text* Many flowering plant species have a facultative or obligate dependence on insect pollination for reproductive success. Anthropogenic disturbance may alter these species interactions, but the extent to which structural changes to plant-pollinator networks affect plant species mating systems is not well understood. * We used long-term livestock grazing of a birch wood ecosystem to test whether disturbance of this semi-natural habitat altered floral resources, the structure of plant–insect visitation networks and the mating system of a focal plant species, Cirsium palustre. * Grazed habitat had a higher species richness of floral resources for pollinators. Visitation networks in grazed habitats were larger, more diverse, with an increase in the number of pollinators per plant species. Controlling for sampling effects, however, showed networks in grazed habitats were less nested and revealed a positive correlation between network connectance and floral species richness. * Network connectance was negatively related to C. palustre outcrossing rate within grazed and ungrazed sites. However, on average, the effects of grazing, including greater mean connectance, produced higher overall outcrossing rates and more pollen donors compared with ungrazed habitat. The number of different pollen donors, spatial genetic structure and mating among close relatives were all correlated with greater extent of suitable C. palustre habitat in the landscape, consistent with the effects of increasing plant population size but limited seed dispersal. * Pre-adaptation of C. palustre to disturbance coupled with a preponderance of highly dispersive flies attracted to the greater food resources in grazed habitat is a likely mechanism underpinning this increased pollen transport. * Habitat modification by long-term mammalian grazing fundamentally shifted visitation network structure and the state of a plant mating system, indicating how ecosystem disturbance can cascade across levels of biological organization through altered interspecific interactions. Cirsium palustre retains flexibility to bias reproduction towards selfing where pollen donor diversity is limited; such reproductive flexibility may be an important mechanism structuring plant populations in human-modified landscapes
Effects of vegetation structure and floristic diversity on detritivore, herbivore and predatory invertebrates within calcareous grasslands
No full textCalcareous grasslands in Europe have shown wide scale declines in their extent and quality as a result of modern agricultural practices, increased atmospheric eutrophication and lack of management. In addition to being a key habitat for specialist plants, calcareous grasslands are also important for many threatened invertebrates. In this UK based study, we investigated the impact of military vehicle activity, floral species richness and vegetation structure on assemblages of detritivore, herbivore and predatory invertebrates. We also consider the impact that disturbance by military vehicle activity on the proportion of invertebrate species capable of flight, a surrogate for dispersal ability. Sward height was negatively correlated with detritivore, herbivore and predator species richness. Herbivores species richness was positively correlated with both forb and grass species richness. Spatial variation in the number of plant species was negatively correlated with herbivore species richness. Those sites most heavily disturbed by military vehicle activity supported the lowest proportions of flightless invertebrates. Successful management for calcareous grassland invertebrates should aim to maintain short swards with high floristic diversity, in terms of both the forbs and grasses. It should be noted, however, that these findings refer to principally surface rather than sward active invertebrates. While disturbance associated with military vehicle activity was not found to affect invertebrate species richness, it has negative consequences for the structure of invertebrate assemblages by selecting against invertebrates with low dispersal ability. To support invertebrate diversity in calcareous grasslands we emphasise the need for variety in the timing and type of management applied to promote heterogeneity in sward structure
E-Planner: a web-based tool for planning environmental enhancement on British agricultural land
No full textE-Planner is a free, web-based, application which provides land managers with fine-scale maps of the suitability of agricultural land in Great Britain for environmental enhancement. E-Planner is designed to streamline decision-making around the choice and spatial targeting of environmental management interventions. Suitability scores are calculated by integrating a range of biophysical data sets and presented as easy-to-interpret maps, at fine resolutions (5 m) equivalent to those used by precision agriculture technology.
The information provided by E-Planner is important for landscape-to field-scale spatial targeting of farm management to maximise the efficiency of both crop production and environmental delivery. Whilst many datasets and tools support the former, equivalents for environmental factors are not widely available. The methods used by E-Planner for collating and presenting data on environmental constraints and drivers are widely applicable, and efficient spatial targeting of agronomic and environmental management forms an essential step towards sustainable agriculture, a global issue
Can long-term floodplain meadow recreation replicate species composition and functional characteristics of target grasslands?
No full text1. The recreation of species-rich grassland represents a key EU agri-environment policy initiative intended to maintain native biodiversity and to support the provision of ecosystem services. Understanding the long-term potential for recreation success is crucial to the evaluation of such schemes.
2. We use a single-site long-term data set (22 years) to test the consequences of grazing recreation management in re-establishing plant community composition and functional trait structure as assessed relative to pristine examples of target floodplain meadows.
3. Following a July hay cut, late summer grazing of the re-growth by either sheep or cattle resulted in an increase in the similarity of plants species composition to the target floodplain meadows, but only in terms of what species had colonized, not in terms of their relative frequencies.
4. Where grazing in late summer was applied, the functional traits of the meadows undergoing recreation became similar to those of the target floodplain meadows only where grazing management was used. When plant traits were divided into subcategories (e.g. regeneration, seed biology, life-form, environmental associations), only those traits linked with plant phenology failed to show evidence of a temporal shift towards the functional trait structure of floodplain meadows.
5. Synthesis and applications:. Under typical grazing management colonization by the majority of species that characterize the target habitat type is predicted to take over 150 years. In contrast, recreation of functional trait structure can occur over a considerably shorter time-scale (>70 years). The potential to provide functionally equivalent grasslands that deliver analogous ecosystem services to those of the target habitat type is therefore a more realistic goal for recreation. We suggest that the time-scale needed to recreate grasslands puts into question the benefits of compensation schemes that allow grasslands to be lost to development (i.e. gravel extraction) in exchange for future recreation at other sites
Fate of semi-natural grassland in England between 1960 and 2013: a test of national conservation policy
No full textIt is well documented that significant losses in semi-natural grassland occurred across
Europe during the second half of the twentieth century. However, comparatively few
studies have investigated and quantified the fate of large numbers of individual grassland
areas. This is important for understanding the causes of decline, and consequently
establishing new policies to conserve and restore lost habitats. This study addresses this
problem; GIS was used to compare historic survey data collected between 1960 and 1981
with two contemporary spatial datasets of habitats in England. The datasets included the
Priority Habitats Inventory 2013 and the Land Cover Map 2007 and this was undertaken for
different types of semi-natural grassland across England. Considerable decreases occurred
across the different grassland types, with a loss of 47% of studied semi-natural grasslands
sites in England over 32–53 years. Of this, the majority of grassland was lost to conversion to
agriculturally-improved grassland or arable cultivation, 45% and 43% respectively. Changes
to woodland and urban areas were also evident, but on a much smaller scale. Sites receiving
statutory protection as a Site of Special Scientific Interest were found to have retained
more grassland (91%), compared with non-protected sites (27%), thus highlighting the
effectiveness of this aspect of current conservation policy in England, and the need for this
to continue in the future
Managing plant population spread: prediction and analysis using a simple model
No full textModels can be used to direct the management of population spread for the control of invasives or to encourage species of conservation value. Analytical models are attractive because of their theoretical basis and limited data requirements, but there is concern that their simplicity may limit their practical utility. We address the applied use of simple models in a study of a declining annual herb, Rhinanthus minor. We parameterized a population-spread model using field data on demography and dispersal for four management systems: grazed only (GR), hay-cut once (H1), hay-cut twice (H2), and hay-cut with autumn grazing (HG). Within a replicated experiment we measured spread rates of introduced R. minor populations over eight years. The modeled and measured spread rates were very similar in terms of both patterns of management effects and absolute values, so that in both cases HG > H2, H1 > GR. The treatments affected both dispersal and demography (establishment and survival) and so we used decomposition approaches to analyze the major causes of differences in population spread. Increased dispersal under hay-cutting was more important than demographic changes and accounted for 70% of the differences in spread rate between the hay-cut and grazed-only treatments. Furthermore, management effects on the tail of the dispersal curve were by far the most critical in governing spread. This study suggests that simple models can be used to inform practical conservation management, and we demonstrate straightforward uses of our model to predict the impacts of different management strategies. While simple models can give accurate projections, we emphasize that they must be parameterized with high-quality data gathered at the appropriate spatial scale
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