Showing papers by "Adrian C. Newton published in 2009"

Enhancement of biodiversity and ecosystem services by ecological restoration: a meta-analysis.

Abstract: 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.

Integrating pests and pathogens into the climate change/food security debate

Abstract: While many studies have demonstrated the sensitivities of plants and of crop yield to a changing climate, a major challenge for the agricultural research community is to relate these findings to the broader societal concern with food security. This paper reviews the direct effects of climate on both crop growth and yield and on plant pests and pathogens and the interactions that may occur between crops, pests, and pathogens under changed climate. Finally, we consider the contribution that better understanding of the roles of pests and pathogens in crop production systems might make to enhanced food security. Evidence for the measured climate change on crops and their associated pests and pathogens is starting to be documented. Globally atmospheric [CO(2)] has increased, and in northern latitudes mean temperature at many locations has increased by about 1.0-1.4 degrees C with accompanying changes in pest and pathogen incidence and to farming practices. Many pests and pathogens exhibit considerable capacity for generating, recombining, and selecting fit combinations of variants in key pathogenicity, fitness, and aggressiveness traits that there is little doubt that any new opportunities resulting from climate change will be exploited by them. However, the interactions between crops and pests and pathogens are complex and poorly understood in the context of climate change. More mechanistic inclusion of pests and pathogen effects in crop models would lead to more realistic predictions of crop production on a regional scale and thereby assist in the development of more robust regional food security policies.

Species Distribution Modeling in the Tropics: Problems, Potentialities, and the Role of Biological Data for Effective Species Conservation:

Abstract: In this paper we aim to investigate the problems and potentialities of species distribution modeling (SDM) as a tool for conservation planning and policy development and implementation in tropical regions. We reviewed 123 studies published between 1995 and 2007 in five of the leading journals in ecology and conservation, and examined two tropical case studies in which distribution modeling is currently being applied to support conservation planning. We also analyzed the characteristics of data typically used for fitting models within the specific context of modeling tree species distribution in Central America. The results showed that methodological papers outnumbered reports of SDMs being used in an applied context for setting conservation priorities, particularly in the tropics. Most applications of SDMs were in temperate regions and biased towards certain organisms such as mammals and birds. Studies from tropical regions were less likely to be validated than those from temperate regions. Unpublished data from two major tropical case studies showed that those species that are most in need of conservation actions, namely those that are the rarest or most threatened, are those for which SDM is least likely to be useful. We found that only 15% of the tree species of conservation concern in Central America could be reliably modelled using data from a substantial source (Missouri Botanical Garden VAST database). Lack of data limits model validation in tropical areas, further restricting the value of SDMs. We concluded that SDMs have a great potential to support biodiversity conservation in the tropics, by supporting the development of conservation strategies and plans, identifying knowledge gaps, and providing a tool to examine the potential impacts of environmental change. However, for this potential to be fully realized, problems of data quality and availability need to be overcome. Weaknesses in current biological datasets need to be systematically addressed, by increasing collection of field survey data, improving data sharing and increasing structural integration of data sources. This should include use of distributed databases with common standards, referential integrity, and rigorous quality control. Integration of data management with SDMs could significantly add value to existing data resources by improving data quality control and enabling knowledge gaps to be identified.

Taxonomic homogenization of woodland plant communities over 70 years.

Abstract: Taxonomic homogenization (TH) is the increasing similarity of the species composition of ecological communities over time. Such homogenization represents a form of biodiversity loss and can result from local species turnover. Evidence for TH is limited, reflecting a lack of suitable historical datasets, and previous analyses have generated contrasting conclusions. We present an analysis of woodland patches across a southern English county (Dorset) in which we quantified 70 years of change in the composition of vascular plant communities. We tested the hypotheses that over this time patches decreased in species richness, homogenized, or shifted towards novel communities. Although mean species richness at the patch scale did not change, we found increased similarity in species composition among woodlands over time. We concluded that the woodlands have undergone TH without experiencing declines in local diversity or shifts towards novel communities. Analysis of species characteristics suggested that these changes were not driven by non-native species invasions or climate change, but instead reflected reorganization of the native plant communities in response to eutrophication and increasingly shaded conditions. These analyses provide, to our knowledge, the first direct evidence of TH in the UK and highlight the potential importance of this phenomenon as a contributor to biodiversity loss.

Deployment of diversity for enhanced crop function

Abstract: Mixtures of genotypes are the norm in natural and seminatural ecosystems and subsistence agriculture but have been replaced by pure genotypes in modern agriculture to maximise profitability in high-input systems. However, crop function with respect to the stability of yield and quality in particular tends to be lost in this process. Diversity can be reintroduced into cropping systems as a trait not only to confer stability but also to exploit synergies between component genotypes, compensating for potential performance losses against the best performing genotype in any given season or location. Quality need not be compromised, and research has demonstrated practical development and deployment approaches, which challenge the assumed benefits of current approaches to agronomy and achieve enhanced crop function.

Remote sensing and the future of landscape ecology

Abstract: Landscape ecology focuses on the analysis of spatial pattern and its relationship to ecological processes. As a scientifi c discipline, landscape ecology has grown rapidly in recent years, supported by developments in GIS and spatial analysis techniques. Although remote sensing data are widely employed in landscape ecology research, their current and potential roles have not been evaluated critically. To provide an overview of current practice, 438 research papers published in the journal Landscape Ecology for the years 2004–2008 were examined for information about use of remote sensing. Results indicated that only 36% of studies explicitly mentioned remote sensing. Of those that did so, aerial photographs and Landsat satellite sensor images were most commonly used, accounting for 46% and 42% of studies, respectively. The predominant application of remote sensing data across these studies was for thematic mapping purposes. This suggests that landscape ecologists have been relatively slow to recognize the potential value of recent developments in remote sensing technologies and methods. The review also provided evidence of a frequent lack of key detail in studies recently published in Landscape Ecology, with 75% failing to provide any assessment of uncertainty or error relating to image classifi cation and mapping. It is suggested that the role of remote sensing in landscape ecology might be strengthened by closer collaboration between researchers in the two disciplines, by greater integration of diverse remote sensing data with ecological data, and by increased recognition of the value of remote sensing beyond land-cover mapping and pattern description. This is illustrated by case studies drawn from Latin America (focusing on forest loss and fragmentation) and the UK (focusing on habitat quality for woodland birds). Such approaches might improve the analytical and theoretical rigour of landscape ecology, and be applied usefully to issues of outstanding societal interest, such as the impacts of environmental change on biodiversity and ecosystem services.

Toward integrated analysis of human impacts on forest biodiversity: lessons from Latin America.

Abstract: Although sustainable forest management (SFM) has been widely adopted as a policy and management goal, high rates of forest loss and degradation are still occurring in many areas. Human activities such as logging, livestock husbandry, crop cultivation, infrastructural development, and use of fire are causing widespread loss of biodiversity, restricting progress toward SFM. In such situations, there is an urgent need for tools that can provide an integrated assessment of human impacts on forest biodiversity and that can support decision making related to forest use. This paper summarizes the experience gained by an international collaborative research effort spanning more than a decade, focusing on the tropical montane forests of Mexico and the temperate rain forests of southern South America, both of which are global conservation priorities. The lessons learned from this research are identified, specifically in relation to developing an integrated modeling framework for achieving SFM. Experience has highlighted a number of challenges that need to be overcome in such areas, including the lack of information regarding ecological processes and species characteristics and a lack of forest inventory data, which hinders model parameterization. Quantitative models are poorly developed for some ecological phenomena, such as edge effects and genetic diversity, limiting model integration. Establishment of participatory approaches to forest management is difficult, as a supportive institutional and policy environment is often lacking. However, experience to date suggests that the modeling toolkit approach suggested by Sturvetant et al. (2008) could be of value in such areas. Suggestions are made regarding desirable elements of such a toolkit to support participatory-research approaches in domains characterized by high uncertainty, including Bayesian Belief Networks, spatial multi-criteria analysis, and scenario planning.

Biological invasions: benefits versus risks.

Abstract: A comprehensive assessment of biological invasions (“Will threat of biological invasions unite the European Union?” P. E. Hulme et al. , Policy Forum, 3 April, p. [40][1]) requires a quantification of the benefits provided to humans by the introduced species as well as their negative impacts.

Movement rates of woodland invertebrates: a systematic review of empirical evidence

Abstract: 1. A systematic review was conducted to gather empirical evidence on movement rates of invertebrates associated with woodland. 2. Eight scientific literature databases were systematically searched for relevant studies on invertebrates associated with woodland habitat. 3. Twenty-five studies were identified that met the search selection criteria, which provided estimates of movement rate for 30 invertebrate species associated with woodland habitat. These 30 species represented insect species only, including 17 carabid (ground) beetle, eight butterfly, two bark beetle, two ant, and one moth species. From 2000 to 2008, only six studies were identified, indicating a current lack of dispersal-related studies for woodland invertebrates. 4. A meta-analysis of studies on ground-dwelling species indicated that carabid beetle species that were strongly associated with woodland habitat were found to move more slowly than more generalist species (median: 2.1 m day−1 vs. 11.0 m day−1). Furthermore, for carabid beetles it was found that body size was positively correlated with movement rate. 5. The lack of field measurements of movement and dispersal ability for all but a tiny minority of woodland invertebrates indicates a substantial knowledge gap that should be addressed by future research, which might usefully test whether the patterns identified for carabid beetles are generally applicable.

The Red List of trees of Central Asia

Abstract: Many of the world’s fruit and nut trees are seriously threatened with extinction, according to the newly released Red List of Trees of Central Asia. The list is published by Fauna and Flora International (FFI) in collaboration with BGCI as part of the Global Trees Campaign. The report identifies 44 tree species in Kyrgyzstan, Kazakhstan, Uzbekistan, Turkmenistan and Tajikistan as globally threatened with extinction, such as Pyrus korshinskyi, pictured left, a pear species identified as Critically Endangered. Many of these species occur in the unique fruit and nut forests of Central Asia – an estimated 90% of which have been destroyed in the past 50 years.

Quantitative evolution of aggressiveness of powdery mildew under two‐cultivar barley mixtures

Abstract: The effects of cultivar mixtures on the evolution of aggressiveness of barley powdery mildew (Blumeria graminis f.sp. hordei) were modelled. It was found that the rate and direction of evolution of pathogen aggressiveness in a race-non-specific system and value at equilibrium, depends on initial resistance levels, proportions of component cultivars, autodeposition rates, the relative magnitude of the benefit of autoinfection, and the cost of alloinfection of spores. In the model, mixing cultivars in any proportions tended to reduce the aggressiveness of pathogens at equilibrium compared with pure stands, but this effect decreased when two mixture components were extremely unbalanced in proportion. Under low and medium autodeposition rates, the best control of the evolution of the pathogen was achieved by mixing two components in roughly equal proportions. The magnitude of aggressiveness at equilibrium increased as autodeposition rates increased. Though the level of initial resistance of mixture components did not have an impact on the aggressiveness of pathogens at equilibrium, it strongly influenced the transient values of aggressiveness and therefore the total amount of disease caused over an evolutionary period. The cost to the pathogen of alloinfection and benefit of autoinfection per se did not affect the final level of aggressiveness, but did affect the time to reach equilibrium. However, the ratio of the cost to the benefit did influence the final aggressiveness of the pathogen.

The influence of habitat availability and landscape structure on the distribution of wood cricket ( Nemobius sylvestris ) on the Isle of Wight, UK

Abstract: Little information is available regarding the landscape ecology of woodland invertebrate species with limited dispersal ability. An investigation was therefore conducted within woodland fragments in an agricultural landscape for the flightless wood cricket (Nemobius sylvestris) on the Isle of Wight, UK. The current pattern of distribution of the species, established during a field survey, was related to measures of habitat availability and habitat isolation/fragmentation. Results revealed that wood cricket populations were patchily distributed and mainly found in relatively large mature woodland fragments situated closely (<50 m) to another occupied site. Although the occurrence of wood cricket was related to fragment area, isolation, habitat availability and woodland age, a logistic regression model revealed that presence of the species was most accurately predicted by fragment isolation and area alone. These results highlight the vulnerability of relatively immobile woodland invertebrate species, such as wood cricket, to the impacts of habitat loss and fragmentation.

Habitat requirements for the conservation of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae) on the Isle of Wight, UK

Abstract: In the UK, wood cricket (Nemobius sylvestris) is a ‘Species of Conservation Concern’, being restricted to only three areas in southern England. Little information is available on the specific habitat requirements of this species. In 2006, a field investigation within three woodlands on the Isle of Wight was undertaken to identify its habitat preferences. Factors positively influencing wood cricket presence within woodlands included the presence of a well-developed leaf litter layer, relatively low ground vegetation cover and height, low canopy cover and relatively short distances between individual populations. Regression models identified the degree of isolation and variables describing vegetation structure as the main predictors for wood cricket presence within woodland fragments. The results of this study indicate the preference of wood cricket for open wooded edges. Conservation efforts for this species should focus on continuation of regular management activities aimed at providing permanent open edge habitat within woodlands, to maintain viable populations.

Measuring woodland connectivity for wood cricket (Nemobius sylvestris) on the Isle of Wight, UK

Abstract: Spatial modelling approaches are increasingly used to design and direct management and conservation plans at the landscape scale. One of the main developments is buffer-radius approaches that use information on the dispersal ability of species to create buffers around distinct habitat patches to assess habitat connectivity within the landscape. In this study, Euclidean and least-cost buffers were used to predict functional ecological networks for wood cricket (Nemobius sylvestris) within the wooded landscape of the Isle of Wight, UK. Compared to the Euclidean buffer approach, the least-cost method revealed a higher number of functional networks indicating a high level of habitat fragmentation for wood cricket and similar woodland invertebrate species. Recent habitat network development increased network connectivity in 3 out of 4 cases. The results further highlight the demand for detailed information, both in terms of species specific and in terms of land cover data, for using least-cost modelling tools effectively in conservation planning.

Impact of soil tillage on the robustness of the genetic component of variation in phosphorus (P) use efficiency in barley (Hordeum vulgare L.)

Abstract: In order to improve the sustainability of agriculture it is imperative that the P-use efficiency of temperate cereal crops be improved. This can be achieved both by agronomic and genetic approaches. While many studies have demonstrated genotypic variation in P-use efficiency in a number of cereal species the robustness of this genetic variation with variation in environment is rarely considered. In this paper we describe an experiment in which we compare the P-nutrition of winter and spring barley genotypes grown in a field trial with contrasting cultivation treatments (conventional vs. minimum tillage) which have been developed over a number of years. We demonstrate that while there is significant variation between genotypes in their P nutrition that this variation is not comparable between cultivation treatments and only one winter barley genotype (cv. Gleam) has beneficial P-use efficiency traits in both cultivation systems. These data suggest that it may be possible to identify a genetic component to variation in P nutrition in barley but that a large interaction with environmental variables may limit the usefulness of any genes or markers discovered for improving P-use efficiency to the conditions under which the screening was performed.

Blending of wheat for Resilience, Improved Distilling quality and Greater Environmental Stability (BRIDGES)

Abstract: 1 Summary 2 Technical report 7 Introduction 7 Materials and methods 9 Multi-site trials 9 Yield sensitivity analysis 12 Sampling of commercial sites 13 Results 13 Multi-site trials 13 Multi-site trials : stability analyses 16 SCRI site nitrogen multi-entry trial 17 Commercial crops 19 Discussion 20 References 22