Anita Diaz

Enhancement of Biodiversity and Ecosystem Services by Ecological Restoration: A Meta-Analysis

Assessing Ecological Restoration In the wake of the Millennium Ecosystem Assessment, the analysis of ecosystem services, and their relationship to biodiversity, has become one of the most rapidly developing research themes in environmental science. At the same time, ecological restoration is widely being implemented as a response to environmental degradation and biodiversity loss. Rey Benayas et al. (p. 1121, published online 30 July) link these themes in a meta-analysis of the impacts of ecological restoration actions on provision of ecosystem services and biodiversity conservation. The analysis of 89 published restoration projects worldwide establishes that ecological restoration does, in general, have positive impacts on both biodiversity and provision of ecosystem services. These effects are especially marked in the tropics. Thus, ecological restoration actions may indeed deliver benefits, both in terms of biodiversity conservation and supporting human livelihoods. Restoration, biodiversity, and ecosystem services are positively linked in a wide range of ecosystem types across the globe. Ecological restoration is widely used to reverse the environmental degradation caused by human activities. However, the effectiveness of restoration actions in increasing provision of both biodiversity and ecosystem services has not been evaluated systematically. A meta-analysis of 89 restoration assessments in a wide range of ecosystem types across the globe indicates that ecological restoration increased provision of biodiversity and ecosystem services by 44 and 25%, respectively. However, values of both remained lower in restored versus intact reference ecosystems. Increases in biodiversity and ecosystem service measures after restoration were positively correlated. Results indicate that restoration actions focused on enhancing biodiversity should support increased provision of ecosystem services, particularly in tropical terrestrial biomes.

Evidence for stabilising selection acting on flowering time in Arum maculatum (Araceae): the influence of phylogeny on adaptation

Abstract The relationship between flowering time and reproductive success was investigated in the fly-pollinated, monoecious perennial herb Arum maculatum L. (Araceae). This species temporarily traps its principle pollinator, a psychodid midge. Probability of fruit set was analysed in relation to early, peak and late periods of the flowering phenology of four British populations between 1992 and 1997. In three out of five cases, plants which flowered during early and late periods were significantly less likely to set fruit. In addition, one population showed a similar relationship for percentage fruit set of individual inflorescences, and seeds from peak-flowering plants were significantly heavier. There was no variation in number of female flowers per inflorescence over the flowering season. Probability of fruit set appears to be mediated by the likelihood of trapping psychodid midges that have previously been trapped and picked up pollen, an unlikely event during early and late flowering periods when few inflorescences are open. The majority of plants in all populations produce only one inflorescence which means that timing of flowering may be crucial to reproductive success. We interpret our findings as evidence that stabilising selection may be acting on some populations and/or during some years. The ultimate cause, however, can be related to the very short (12–18 h) female phase of each inflorescence, a phylogenetically conservative trait within the Araceae.

Factors affecting the concentration in seven-spotted ladybirds (Coccinella septempunctata L.) of Cd and Zn transferred through the food chain.

The transfer of Cd and Zn from soils amended with sewage sludge was followed through a food chain consisting of wheat, aphids and the predator Coccinella septempunctata. Multiple regression models were generated to predict the concentrations of Cd and Zn in C. septempunctata. No significant model could be generated for Cd, indicting that the concentration of this metal was maintained within relatively narrow limits. A model predicting 64% of the variability in the Zn concentration of C. septempunctata was generated from of the concentration of Zn in the diet, time and rate of Zn consumption. The results suggest that decreasing the rate of food consumption is an effective mechanism to prevent the accumulation of Zn and that the availability of Zn in the aphid prey increased with the concentration in the aphids. The results emphasise the importance of using ecologically relevant food chains and exposure pathways during ecotoxicological studies.

Can plant palatability trials be used to predict the effect of rabbit grazing on the flora of ex-arable land?

Abstract Surplus food production has led to increased interest in taking land out of arable farming, notably under set-aside regulations, and converting it into grasslands that resemble semi-natural plant communities. Despite the value of being able to predict the long-term success of such habitat creation projects, there is little ecological data available on which to base such predictions. This study tests whether plant palatability trials can be a useful method to predict the effect of grazing by rabbits on the success of individual species growing in grasslands. The palatability of 22 common, grassland species was tested by offering wild rabbits pot-grown plants of each species in a variety of grassland vegetation backgrounds in NE Scotland. Plants were inserted into plots consisting of a regular grid of holes cut into rabbit-grazed grasslands. The palatability of each species was tested in 10 such plots, on 20 occasions each. Plots varied in their vegetation composition and were each grazed by rabbits from a different warren. Plant species were found to differ greatly in their palatability to rabbits. Palatability was found to be unaffected by the composition of the surrounding vegetation. A survey was also carried out to determine the floristic composition of ungrazed and rabbit grazed swards of 8-year old set-aside. A strong relationship was found between the palatability of most plant species and their comparative abundance in ungrazed and grazed swards. Possible reasons for the few exceptions are discussed. In general, these findings indicate that palatability trials can be a useful and robust method of predicting the effect of rabbits on the success of individual plant species growing in grasslands. A method such as this, that allows the impact of rabbits on floristic composition to be predicted, can be used to inform grassland recreation and management decisions.

Reconstructing the origin and elaboration of insect-trapping inflorescences in the Araceae

UNLABELLED PREMISE OF THE STUDY Floral traps are among the most sophisticated devices that have evolved in angiosperms in the context of pollination, but the evolution of trap pollination has not yet been studied in a phylogenetic context. We aim to determine the evolutionary history of morphological traits that facilitate trap pollination and to elucidate the impact of pollinators on the evolution of inflorescence traps in the family Araceae. • METHODS Inflorescence morphology was investigated to determine the presence of trapping devices and to classify functional types of traps. We inferred phylogenetic relationships in the family using maximum likelihood and Bayesian methods. Character evolution of trapping devices, trap types, and pollinator types was then assessed with maximum parsimony and Bayesian methods. We also tested for an association of trap pollination with specific pollinator types. • KEY RESULTS Inflorescence traps have evolved independently at least 10 times within the Araceae. Trapping devices were found in 27 genera. On the basis of different combinations of trapping devices, six functional types of traps were identified. Trap pollination in Araceae is correlated with pollination by flies. • CONCLUSIONS Trap pollination in the Araceae is more common than was previously thought. Preadaptations such as papillate cells or elongated sterile flowers facilitated the evolution of inflorescence traps. In some clades, imperfect traps served as a precursor for the evolution of more elaborate traps. Traps that evolved in association with fly pollination were most probably derived from mutualistic ancestors, offering a brood-site to their pollinators.

The design of trapping devices in pollination traps of the genus Arum (Araceae) is related to insect type

Pollinators have long been known to select for floral traits, but the nature of this relationship has been little investigated in trap pollination systems. We investigated the trapping devices of 15 Arum spp. and compared them with the types of insects trapped. Most species shared a similar general design of trap chamber walls covered in downward-pointing papillate cells, lacunose cells in the chamber wall and elongated sterile flowers partially blocking the exit of the trap. However, there was significant variation in all these morphological features between species. Furthermore, these differences related to the type of pollinator trapped. Most strikingly, species pollinated by midges had a slippery epidermal surface consisting of smaller papillae than in species pollinated by other insects. Midge-pollinated species also had more elongated sterile flowers and tended to have a larger lacunose area. We conclude that pollination traps evolve in response to the type of insect trapped and that changes to the slippery surfaces of the chamber wall are an important and previously little recognized variable in the design of pollination traps.

Sika deer distribution and habitat selection: the influence of the availability and distribution of food, cover, and threats

Large populations of sika deer occur in lowland heath, woodland, and grassland mosaics in southern England. Previous studies have focused on understanding single factors potentially affecting distribution and habitat selection of sika deer rather than considering simultaneously effects of landscape configuration and human disturbance on their distribution and habitat selection. This study measured effects of habitat availability, landscape structure, and human disturbance on where sika deer placed their home ranges and habitat selection within those ranges. Two main hypotheses were tested: (1) habitat selection differs according to landscape structure and habitat availability at both landscape and home range scales and (2) distribution of sources of human disturbance within the home range of deer affects their distribution. Results from radiotracking 31 females provided support for the first hypothesis and partial support for the second. Habitat selection at the landscape and home range scales differed between landscapes with different habitat structure and availability and was driven by distribution and availability of food and cover and a perceived risk linked to disturbance. Furthermore, deer selected open areas close to cover and this selection was stronger with presence of human disturbance, although results differed between study areas with different habitat distribution and level of disturbance. The study highlights the importance for managing deer of a balance between grazing and cover resources and the distribution of human disturbance.

14. Ecological impacts of Sika Deer on Poole Harbour saltmarshes

Abstract This study investigates the effect of an introduced species, Sika Deer Cervus nippon on saltmarsh plant and infaunal communities. Epidermal fragment analysis was used to identify the plant species eaten by Sika Deer. Vegetation communities in deer exclosures and openly grazed areas were monitored over 4 years to investigate the effect of grazing on plant community composition and structure. The infaunal communities were assessed by extracting sediment cores. Deer were found to graze preferentially on Spartina anglica as intensive grazing led to swards dominated by Salicornia ramosissima even in upper marsh areas. Highest plant diversity was related to intermediate levels of grazing. Overall, higher levels of grazing led to higher abundance of three species of infauna detected in this study: Hydrobia ulvae, Gammarus sp. and Nereis diversicolor. Detailed examination revealed that the high abundance of H. ulvae was related to small quantities of above ground vegetation volume and that the abundance of Gammarus was related to small quantities of below ground vegetation biomass. The possible direct and indirect effects of Sika Deer grazing on bird populations are discussed.

Borderland spaces for learning partnership: opportunities, benefits and challenges

Abstract This paper uses case studies and secondary literature to critically examine how learning spaces inhabited by geographers might be used productively as borderland spaces for learning partnership. Borderland spaces are novel, challenging, permissive and liminal, destabilizing traditional power hierarchies. In these spaces, students gain confidence in accepting agency in learning, moving towards critical thinking and reflective judgement, thereby developing self-authorship. They acquire new knowledge, skills and facets to their identity. They also feel anxiety as they take on new roles and adopt a partnership ethos. Faculty must guide students to support their successful navigation into and out of borderland spaces.

A two-pollinator model for the evolution of floral complexity

For a new, more complex floral form to become established in a population it must overcome the problem of frequency-dependent constancy to successfully attract pollinators. This may be achieved by complex floral forms offering absolute greater rewards than the simpler forms, or by complex flowers offering a higher probability of being rewarding because fewer pollinators are able to visit them. In this paper we examine the effect of three pollinator foraging strategies on the ratio of flights within and between floral morphs and hence on the probability of a new morph establishing in a population without offering a greater reward. We incorporate pollinator behaviour based around observations of two pollinator species systems into three models of competition for pollinators. In the first model the constancy of the pollinator of the new floral morph is a function only of the foraging strategy of the existing pollinator of the original floral morph. In the next model the constancy of the second pollinator is determined by the number of rewarding flowers of each floral morph left by the original pollinator and in the third model it is determined by the ratio of rewarding flowers of each morph left by the original pollinator. The results demonstrate that under conditions of intense competition for pollinators, new, more complex floral forms are indeed able to attract high levels of constant pollinators without offering intrinsically higher rewards. However, for this to occur constancy in one of the pollinators must be a function of the ratio of rewarding to non-rewarding flowers of both floral forms. One prediction from our results is that sympatric speciation of floral complexity based on a higher probability of reward is more likely to occur in flowers offering rewards of pollen rather than nectar. This is because the cost of visiting non-rewarding flowers is usually higher where the reward is pollen rather than nectar. We also predict that complex flowers occurring at low frequency, which offer rewards of nectar, may need intrinsically greater rewards if they are to successfully attract pollinators.