Causal relationships between African mahoganies exports and deforestation in Ghana: policy implications

When exploiting forest resources, the resource use must be sustainable if its use is to support its function in the natural ecosystem. The African mahogany, a prized timber species, is widely exploited, raising policy concerns about the management of forest resources to meet the social, economic, and ecological needs of present and future generations. This paper explores, for the purpose of policy implication, the relationship between the exportation and deforestation of African mahoganies. The analysis employed a Granger causality test within the error correction model to evaluate the direction of causality between African mahoganies exports and deforestation in Ghana. The results suggested that in the short run, there was significant (P < 0.01) unidirectional causality from African mahoganies exports to deforestation. However, there was no directional causality from deforestation to mahogany exports. Thus, mahogany extraction and logging in general are among the major factors contributing to deforestation in Ghana. The general assessment of historical trends in the extraction levels of the two main genera of African mahoganies revealed that Entandrophragma cylindricum and Khaya ivorensis have been the most exploited species over the years. Improvements in, and the enforcement of, existing forest institutions and incentives, as well as related policies, could minimise the rate of deforestation not only of the African mahogany but also in timber logging, thus stemming forest degradation and deforestation in the country.     

Exploring new ways of assessing the effect of regulation on environmental management

Studies indicate that while a variety of factors positively influence voluntary environmental management, regulatory pressures are among the most important. However, most research examines samples representing large manufacturers or single industries, essentially assuming a level of regulatory constraint. Using a sample of heterogeneous facilities, this study finds that facilities can be classified according to the level of regulatory constraint, and that group membership impacts the choice of environmental management strategy when assessed within a utility maximization framework. More extensively regulated facilities implement more individual environmental management practices, but participate in fewer formal voluntary environmental programs (VEPs), compared to other facilities.     

Distinguishing Between Interference and Exploitation Competition for Shelter in a Mobile Fish Population

Understanding the functional significance of shelter for animal populations requires knowledge of the behavioural mechanisms that govern the dynamics of shelter use. Exploitation of shelters may be impeded by mutual interference, yet interference competition can be difficult to distinguish from exploitation competition. We used bullheads (Cottus gobio) as a model system of mobile fish to investigate the effect of intraspecific competition on shelter use. A series of field experiments was conducted under controlled conditions of shelter availability and population density. For each experiment, the location of each individual fish was observed over a period of 10 days. We then constructed a continuous-time Markov-chain model for the movement of fish between shelters and the open stream, which explicitly parameterised exploitation competition and interference competition for shelter and which accounted for two different size-classes of fish. By using a stochastic rather than a deterministic model, we were able to account for the distribution of fish across shelters, and not just the average occupation. Analysis of the model showed strong evidence of exploitation competition, which was highly dependent on body size, and an increased departure rate from shared shelters. Over and above exploitation, interference competition limited the ability of unsheltered fish to colonise vacant shelters at high population densities. Different formulations of the interference competition were compared using the Akaike Information Criterion. The formulation that best fitted the observations modelled interference competition as an increasing function of average shelter occupancy rather than population density per se.     

Vulnerability of exporting nations to the development of a carbon label in the United Kingdom

Carbon labels inform consumers about the amount of greenhouse gases (GHGs) released during the production and consumption of goods, including food. In the future consumer and legislative responses to carbon labels may favour goods with lower emissions, and thereby change established supply chains. This may have unintended consequences.We present the carbon footprint of three horticultural goods of different origins supplied to the United Kingdom market: lettuce, broccoli and green beans. Analysis of these footprints enables the characterisation of three different classes of vulnerability which are related to: transport, national economy and supply chain specifics.There is no simple relationship between the characteristics of an exporting country and its vulnerability to the introduction of a carbon label. Geographically distant developing countries with a high level of substitutable exports to the UK are most vulnerable. However, many developing countries have low vulnerability as their main exports are tropical crops which would be hard to substitute with local produce.In the short term it is unlikely that consumers will respond to carbon labels in such a way that will have major impacts in the horticultural sector. Labels which require contractual reductions in GHG emissions may have greater impacts in the short term.     

Challenges and opportunities for sustainability in regional universities: a case study in Mytilene,Greece

Regional Higher Education Institutions (HEIs) may contribute significantly to the promotion of sustainability through several means connected with their functioning. Nevertheless, several challenges can present themselves during the planning and implementation of such initiatives. The aim of this paper is to underline these limitations through the relevant literature and highlight their main consequences on the achievement of sustainability. An empirical study, investigating the perception of students regarding the constraints to achieving sustainability in a regional university of Greece, was conducted and is discussed in relation to the university's specific characteristics – its fragmented nature with campuses situated on five Aegean islands, its public status as well as its role in creating and dispersing knowledge in less developed areas of the country.     

Population and seasonal variation in response to prey calls by an eavesdropping bat

The fringe-lipped bat, Trachops cirrhosus, is an eavesdropping predator that hunts frogs and katydids by approaching these preys' sexual advertisement calls. In captivity, bats can rapidly learn to associate novel acoustic stimuli with food rewards. It is unknown how this learning ability is related to foraging behavior in the wild where prey and the calls that identify them vary over space and time. In two bat populations that differ in available prey species (Soberanía, Panama, and La Selva, Costa Rica), we presented wild-caught bats with frog calls, katydid calls, and control stimuli. Bats in Soberanía were significantly more responsive to complex calls and choruses of the túngara frog, Physalaemus pustulosus, than were bats in La Selva. La Selva bats were significantly more responsive to katydid calls (Steirodon sp.) than Soberanía bats. We also examined seasonal variation in bat response to prey cues. Bats were captured in Soberanía in dry and wet seasons and presented with the calls of a dry season breeding frog (Smilisca sila), a wet season breeding frog (P. pustulosus), and four katydid species. Bats captured in the dry season were significantly more responsive to the calls of S. sila than bats captured in the wet season, but there were no seasonal differences in response to the calls of P. pustulosus or the katydid calls. We demonstrate plasticity in the foraging behavior of this eavesdropping predator but also show that response to prey cues is not predicted solely by prey availability.