Role of nesting resources in organising diverse bee communities in a Mediterranean landscape

1. The habitat components determining the structure of bee communities are well known when considering foraging resources; however, there is little data with respect to the role of nesting resources. 2. As a model system this study uses 21 diverse bee communities in a Mediterranean landscape comprising a variety of habitats regenerating after fire. The findings clearly demonstrate that a variety of nesting substrates and nest building materials have key roles in organising the composition of bee communities. 3. The availability of bare ground and potential nesting cavities were the two primary factors influencing the structure of the entire bee community, the composition of guilds, and also the relative abundance of the dominant species. Other nesting resources shown to be important include availability of steep and sloping ground, abundance of plant species providing pithy stems, and the occurrence of pre-existing burrows. 4. Nesting resource availability and guild structure varied markedly across habitats in different stages of post-fire regeneration; however, in all cases, nest sites and nesting resources were important determinants of bee community structure.

Landscape effects on crop pollination services: are there general patterns?

Pollination by bees and other animals increases the size, quality, or stability of harvests for 70% of leading global crops. Because native species pollinate many of these crops effectively, conserving habitats for wild pollinators within agricultural landscapes can help maintain pollination services. Using hierarchical Bayesian techniques, we synthesize the results of 23 studies - representing 16 crops on five continents - to estimate the general relationship between pollination services and distance from natural or semi-natural habitats. We find strong exponential declines in both pollinator richness and native visitation rate. Visitation rate declines more steeply, dropping to half of its maximum at 0.6 km from natural habitat, compared to 1.5 km for richness. Evidence of general decline in fruit and seed set - variables that directly affect yields - is less clear. Visitation rate drops more steeply in tropical compared with temperate regions, and slightly more steeply for social compared with solitary bees. Tropical crops pollinated primarily by social bees may therefore be most susceptible to pollination failure from habitat loss. Quantifying these general relationships can help predict consequences of land use change on pollinator communities and crop productivity, and can inform landscape conservation efforts that balance the needs of native species and people.

Landscape typology in the Mediterranean context: a tool for habitat restoration

Despite the wide use of Landscape Character Assessment (LCA) as a tool for landscape planning in NW Europe, there are few examples of its application in the Mediterranean. This paper reports on the results from the development of a typology for LCA in a study area of northern Sardinia, Italy to provide a spatial framework for the analysis of current patterns of cork oak distribution and future restoration of this habitat. Landscape units were derived from a visual interpretation of map data stored within a GIS describing the physical and cultural characteristics of the study area. The units were subsequently grouped into Landscape Types according to the similarity of shared attributes using Two Way Indicator Species Analysis (TWINSPAN). The preliminary results showed that the methodology classified distinct Landscape Types but, based on field observations, there is a need for further refinement of the classification. The distribution and properties of two main cork oak habitats types was examined within the identified Landscape Types namely woodlands and wood pastures using Patch Analyst. The results show very clearly a correspondence between the distribution of cork oak pastures and cork oak woodland and landscape types. This forms the basis of the development of strategies for the maintenance, restoration and recreation of these habitat types within the study area, ultimately for the whole island of Sardinia. Future work is required to improve the landscape characterisation , particularly with respect to cultural factors, and to determine the validity of the landscape spatial framework for the analysis of cork oak distribution as part of a programme of habitat restoration and re-creation.

The effects of cattle grazing on plant-pollinator communities in a fragmented Mediterranean landscape

The main aims of this study were to assess grazing impacts on bee communities in fragmented mediterranean shrubland (phrygana) and woodland habitats that also experience frequent wildfires, and to explain the mechanisms by which these impacts occur. Fieldwork was carried out in 1999 and 2000 on Mount Carmel, in northern Israel, a known hot-spot for bee diversity. Habitats with a range of post-burn ages and varying intensities of cattle grazing were surveyed by transect recording, grazing levels, and the diversity and abundance of both flowers and bees were measured. The species richness of both bees and flowers were highest at moderate to high grazing intensities, and path-analysis indicated that the effects of both grazing and fire on bee diversity were mediated mainly through changes in flower diversity, herb flowers being more important than shrubs. The abundance of bees increased with intensified grazing pressure even at the highest levels surveyed. Surprisingly though, changes in bee abundance at high grazing levels were not caused directly by changes in flower cover. The variation in bee abundance may have been due to higher numbers of solitary bees from the family Halictidae in grazed sites, where compacted ground (nesting resource) and composites (forage resource) were abundant. The effects of grazing on plants were clearest in the intermediate-aged sites, where cattle inhibited the growth of some of the dominant shrubs, creating or maintaining more open patches where light-demanding herbs could grow, thus allowing a diverse flora to develop. Overall, bee communities benefit from a relatively high level of grazing in phrygana. Although bee and flower diversity may decrease under very heavy grazing, the present levels of grazing on Mount Carmel appear to have only beneficial effects on the bee community.

Effect of field margins on moths depends on species mobility: Field-based evidence for landscape-scale conservation

Agri-environment schemes (AES) are widely used policy instruments intended to combat widespread biodiversity declines across agricultural landscapes. Here, using a light trapping and mark-release-recapture study at a field-scale on nine common and widespread larger moth species, we investigate the effect of wide field margins (a popular current scheme option) and the presence of hedgerow trees (a potential scheme option in England) on moth abundance. Of these, we show that wide field margins positively affected abundances, although species did not all respond in the same way. We demonstrate that this variation can be attributed to species-specific mobility characteristics. Those species for which the effect of wide margins was strongest covered shorter distances, and were more frequently recaptured at their site of first capture. This demonstrates that the standard, field-scale uptake of AES may be effective only for less mobile species. We discuss that a landscape-scale approach, in contrast, could deliver significant biodiversity gains, as our results indicate that such an approach (perhaps delivered through targeting farmers to join AES) would be effective for the majority of wider countryside species, irrespective of their mobility level. (C) 2008 Elsevier B.V. All rights reserved.

The effects of spatial and temporal heterogeneity on the population dynamics of four animal species in a Danish landscape

Background: Variation in carrying capacity and population return rates is generally ignored in traditional studies of population dynamics. Variation is hard to study in the field because of difficulties controlling the environment in order to obtain statistical replicates, and because of the scale and expense of experimenting on populations. There may also be ethical issues. To circumvent these problems we used detailed simulations of the simultaneous behaviours of interacting animals in an accurate facsimile of a real Danish landscape. The models incorporate as much as possible of the behaviour and ecology of skylarks Alauda arvensis, voles Microtus agrestis, a ground beetle Bembidion lampros and a linyphiid spider Erigone atra. This allows us to quantify and evaluate the importance of spatial and temporal heterogeneity on the population dynamics of the four species. Results: Both spatial and temporal heterogeneity affected the relationship between population growth rate and population density in all four species. Spatial heterogeneity accounted for 23–30% of the variance in population growth rate after accounting for the effects of density, reflecting big differences in local carrying capacity associated with the landscape features important to individual species. Temporal heterogeneity accounted for 3–13% of the variance in vole, skylark and spider, but 43% in beetles. The associated temporal variation in carrying capacity would be problematic in traditional analyses of density dependence. Return rates were less than one in all species and essentially invariant in skylarks, spiders and beetles. Return rates varied over the landscape in voles, being slower where there were larger fluctuations in local population sizes. Conclusion: Our analyses estimated the traditional parameters of carrying capacities and return rates, but these are now seen as varying continuously over the landscape depending on habitat quality and the mechanisms of density dependence. The importance of our results lies in our demonstration that the effects of spatial and temporal heterogeneity must be accounted for if we are to have accurate predictive models for use in management and conservation. This is an area which until now has lacked an adequate theoretical framework and methodology.

Improving educational functions in botanic gardens by employing landscape narratives

Landscape narrative, combining landscape and narrative, has been employed to create storytelling layouts and interpretive information in some famous botanic gardens. In order to assess the educational effectiveness of using "landscape narrative" in landscape design, the Heng-Chun Tropical Botanical Garden in Taiwan was chosen as research target for an empirical study. Based on cognitive theory and the affective responses of environmental psychology, computer simulations and video recordings were used to create five themed display areas with landscape narrative elements. Two groups of pupils watched simulated films. The pupils were then given an evaluation test and questionnaire, to determine the effectiveness of the landscape narrative. When the content was well associated and matched with the narrative landscape, the comprehension and retention of content was increased significantly. The results also indicated that visual preference of narrative landscape scenes was increased. This empirical study can be regarded as a successful model of integrating landscape narrative and interpretation practice that can be applied to the design of new theme displays in botanic gardens to improve both the effectiveness of interpretation plans and the visual preference of visitors. (c) 2008 Elsevier B.V. All rights reserved.

A method for evaluating alternative landscape management scenarios in relation to the biodiversity conservation of habitats

A perennial issue for land use policy is the evaluation of landscape biodiversity and the associated cost effectiveness of any biodiversity conservation policy actions. Based on the CUA methodology as applied to species conservation, this paper develops a methodology for evaluating the impact on habitats of alternative landscape management scenarios. The method incorporates three dimensions of habitats, quantity change, quality change and relative scarcity, and is illustrated in relation to the alternative landscape management scenarios for the Scottish Highlands (Cairngorms) study area of the BioScene project. The results demonstrate the value of the method for evaluating biodiversity conservation policies through their impact on habitats.

Attitudes of landscape professionals towards naturalistic versus formal urban landscapes in the UK

The last 30 years have seen a tide of interest sweeping across Europe in the development of nature in cities, and an increasing amount of landscape development in urban areas has involved the use of 'naturalistic' styles. This is an increasing attempt to find ways for urbanism and nature to co-exist. However, there have been considerable discussions among professionals regarding the advantages and disadvantages of 'naturalistic' styles in urban areas. This research examines professional attitudes to 'naturalistic' landscape styles in Britain, in contrast to more traditional, formal landscape styles, and aims to find out whether the interest in natural landscapes is really a fashion among landscape professionals. A self-administered postal survey was carried out using both quantitative and qualitative data collection techniques and analysis. The survey included 500 professionals from parks and recreation departments of local authorities, private landscape practices and conservation trusts, and resulted in a satisfactory response rate of 53 %. The results of this study suggested that professionals recognise most of the values attached to naturalistic landscapes in urban areas. However, possible benefits that natural areas may have for urban people are not attached to naturalistic landscapes alone. The study also revealed that the naturalistic style is highly popular among conservation trusts but is less so among professionals from local authorities and private landscape practices who seem to appreciate both styles and believe that these styles are not separable from each other and should co-exist in an urban environment. (C) 2006 Elsevier B.V. All rights reserved.

Mapping the landscape of the lymphocytic choriomeningitis virus stable signal peptide reveals novel functional domains

The stable signal peptide (SSP) of the lymphocytic choriomeningitis virus surface glycoprotein precursor has several unique characteristics. The SSP is unusually long, at 58 amino acids, and contains two hydrophobic domains, and its sequence is highly conserved among both Old and New World arenaviruses. To better understand the functions of the SSP, a panel of point and deletion mutants was created by in vitro mutagenesis to target the highly conserved elements within the SSP. We were also able to confirm critical residues required for separate SSP functions by trans-complementation. Using these approaches, it was possible to resolve functional domains of the SSP. In characterizing our SSP mutants, we discovered that the SSP is involved in several distinct functions within the viral life cycle, beyond translocation of the viral surface glycoprotein precursor into the endoplasmic reticulum lumen. The SSP is required for efficient glycoprotein expression, posttranslational maturation cleavage of GP1 and GP2 by SKI-1/S1P protease, glycoprotein transport to the cell surface plasma membrane, formation of infectious virus particles, and acid pH-dependent glycoprotein-mediated cell fusion.

Assembling spatially explicit landscape models of pollen and spore dispersal by wind for risk assessment

Models of windblown pollen or spore movement are required to predict gene flow from genetically modified (GM) crops and the spread of fungal diseases. We suggest a simple form for a function describing the distance moved by a pollen grain or fungal spore, for use in generic models of dispersal. The function has power-law behaviour over sub-continental distances. We show that air-borne dispersal of rapeseed pollen in two experiments was inconsistent with an exponential model, but was fitted by power-law models, implying a large contribution from distant fields to the catches observed. After allowance for this 'background' by applying Fourier transforms to deconvolve the mixture of distant and local sources, the data were best fit by power-laws with exponents between 1.5 and 2. We also demonstrate that for a simple model of area sources, the median dispersal distance is a function of field radius and that measurement from the source edge can be misleading. Using an inverse-square dispersal distribution deduced from the experimental data and the distribution of rapeseed fields deduced by remote sensing, we successfully predict observed rapeseed pollen density in the city centres of Derby and Leicester (UK).