Variational principles for linear and non-linear elliptic equations

Imperial Users onl

Biodiversity Risks of Adopting Resilience as a Policy Goal

Resilience is increasingly being incorporated into environmental policy at national and global scales. Yet resilience is a contested concept, with a wide variety of definitions proposed in the scientific literature, and little consensus regarding how it should be measured. Consequently, adoption of resilience as a policy goal presents risks to biodiversity conservation, which are considered here in relation to three categories: (1) ambiguity, (2) measurement difficulty, and (3) misuse. While policy makers might welcome the ambiguity of resilience as a concept, as it provides flexibility and opportunities to build consensus, the lack of clear definitions hinders evaluation of policy effectiveness. Policy relating to resilience is unlikely to be evidence-based, as monitoring will be difficult to implement. Vague definitions also provide scope for misuse. This is illustrated by the case of European forests, where resilience is being used as a justification to promote management interventions that will negatively affect biodiversity. To address these risks, there is a need for standard definitions and measures of resilience to be developed for use in policy. Furthermore, there is a need for guidelines, standards, and identification of best practice in relation to resilience policy, to ensure that its implementation does not contribute to biodiversity loss

Dependency of Businesses on Flows of Ecosystem Services: A Case Study from the County of Dorset, UK

Although it is widely assumed that business activity is dependent on flows of ecosystem services (ES), little evidence is available with which to evaluate this contention. To address this knowledge gap, we conducted a questionnaire survey of business dependencies on twenty-six different ES in the English county of Dorset, where the environment supports a significant component of the local economy. Responses were received from 212 businesses across twenty-eight sectors. While virtually all businesses (98%) were familiar with the concept of ES, dependency on ES was highly divided with 50% of businesses surveyed claiming no dependence on any ES flows. The highest businesses dependencies reported in this study were for regulating services with the ES of water quality and waste water treatment being of particular importance to businesses. The results however, advised that greater efforts are needed in highlighting the indirect benefits provided by Dorset’s ecosystems, with eight business sectors (58% of respondents) claiming no or little dependence on supporting and habitat services including the ES of biodiversity, habitats for species and maintenance of genetic diversity. Many businesses also indicated little or no dependence on the globally important ES of pollination and soil condition, which may reflect a lack of awareness of dependencies occurring upstream of their value chains. At the sector level, businesses directly involved in protecting, extracting, or manufacturing raw materials were found to be more dependent on provisioning, regulatory and supporting ES than those operating in the service sector who favored cultural ES. These results highlight the value of assessing business dependencies on ES flows, which could usefully inform environmental management and accounting systems and improve monitoring of business performance, and thereby contribute to achievement of sustainability goals

Dynamics and Conservation Management of a Wooded Landscape under High Herbivore Pressure

We present the use of a spatially explicit model of woodland dynamics (LANDIS-II) to examine the impacts of herbivory in the New Forest National Park, UK, in relation to its management for biodiversity conservation. The model was parameterized using spatial data and the results of two field surveys and then was tested with results from a third survey. Field survey results indicated that regeneration by tree species was found to be widespread but to occur at low density, despite heavy browsing pressure. The model was found to accurately predict the abundance and richness of tree species. Over the duration of the simulations (300 yr), woodland area increased in all scenarios, with or without herbivory. While the increase in woodland area was most pronounced under a scenario of no herbivory, values increased by more than 70% even in the presence of heavy browsing pressure. Model projections provided little evidence for the conversion of woodland areas to either grassland or heathland; changes in woodland structure and composition were consistent with traditional successional theory. These results highlight the need for multiple types of intervention when managing successional landscape mosaics and demonstrate the value of landscape-scale modelling for evaluating the role of herbivory in conservation management

Use of a Bayesian belief network to predict the impacts of commercializing non-timber forest products on livelihoods

Commercialization of non-timber forest products (NTFPs) has been widely promoted as a means of sustainably developing tropical forest resources, in a way that promotes forest conservation while supporting rural livelihoods. However, in practice, NTFP commercialization has often failed to deliver the expected benefits. Progress in analyzing the causes of such failure has been hindered by the lack of a suitable framework for the analysis of NTFP case studies, and by the lack of predictive theory. We address these needs by developing a probabilistic model based on a livelihood framework, enabling the impact of NTFP commercialization on livelihoods to be predicted. The framework considers five types of capital asset needed to support livelihoods: natural, human, social, physical, and financial. Commercialization of NTFPs is represented in the model as the conversion of one form of capital asset into another, which is influenced by a variety of socio-economic, environmental, and political factors. Impacts on livelihoods are determined by the availability of the five types of assets following commercialization. The model, implemented as a Bayesian Belief Network, was tested using data from participatory research into 19 NTFP case studies undertaken in Mexico and Bolivia. The model provides a novel tool for diagnosing the causes of success and failure in NTFP commercialization, and can be used to explore the potential impacts of policy options and other interventions on livelihoods. The potential value of this approach for the development of NTFP theory is discussed

Carbon pools recover more quickly than plant biodiversity in tropical secondary forests.

Although increasing efforts are being made to restore tropical forests, little information is available regarding the time scales required for carbon and plant biodiversity to recover to the values associated with undisturbed forests. To address this knowledge gap, we carried out a meta-analysis comparing data from more than 600 secondary tropical forest sites with nearby undisturbed reference forests. Above-ground biomass approached equivalence to reference values within 80 years since last disturbance, whereas below-ground biomass took longer to recover. Soil carbon content showed little relationship with time since disturbance. Tree species richness recovered after about 50 years. By contrast, epiphyte richness did not reach equivalence to undisturbed forests. The proportion of undisturbed forest trees and epiphyte species found in secondary forests was low and changed little over time. Our results indicate that carbon pools and biodiversity show different recovery rates under passive, secondary succession and that colonization by undisturbed forest plant species is slow. Initiatives such as the Convention on Biological Diversity and REDD+ should therefore encourage active management to help to achieve their aims of restoring both carbon and biodiversity in tropical forests