A conceptual framework for integrated impact assessment of trypanosomiasis interventions

A framework for assessing the integrated impacts of trypanosomiasis interventions that resembles the structure of the DPSIR conceptual model (see EEA 2000) is developed in this study. This framework provides a way to make evident the pressures on the involved systems, define the target groups and levels of analysis, establish cause and effect relationships, organise information about the state of the systems, select appropriate methodologies for impact assessment, identify indicators, scaling up and scaling out the results, promote dynamic learning processes and evidence the potential responses of the society. The structure of this paper is as follows: The main concepts of impact assessment are initially introduced; and an integrated vision of the interaction between environmental, economic and social systems is presented. Then a set of key questions to be considered in the design of impact assessment studies are reviewed. Later, the basic elements of the impact analysis are shown in a logical sequence to present the conceptual framework for integrated impact assessment of trypanosomiasis interventions. Finally, the paper summarises the available methodologies for impact assessment on the different systems and provide some conclusions

Guidelines for assessing environmental and socio-economic impacts of tsetse and trypanosomiasis interventions

This report provides guidelines on methods and tools for conducting impact assessments of T&T (tsetse and trypanosomiasis) interventions on the environmental, social and economic systems and on approaches for the integrated impact assessment of the interventions. The purpose of these guidelines is help donors, development agencies, project implementers and other T&T eradication stakeholders to identify adequate options for assessing the impacts of T&T interventions based on their target level of analysis, available resources and constraints. These guidelines are therefore aimed at helping PATTEC (African Union 's Pan African Tsetse and Trypanosomiasis Eradication Campaign) project managers and their experts target their priorities in environmental and socio-economic impact assessments. This will allow them to address pertinent issues adequately for the benefit of all stakeholders and allocate their resources rationally

Drivers and facilitators of the illegal killing of elephants across 64 African sites

Ivory poaching continues to threaten African elephants. We (1) used criminology theory and literature evidence to generate hypotheses about factors that may drive, facilitate or motivate poaching, (2) identified datasets representing these factors, and (3) tested those factors with strong hypotheses and sufficient data quality for empirical associations with poaching. We advance on previous analyses of correlates of elephant poaching by using additional poaching data and leveraging new datasets for previously untested explanatory variables. Using data on 10 286 illegally killed elephants detected at 64 sites in 30 African countries (2002–2020), we found strong evidence to support the hypotheses that the illegal killing of elephants is associated with poor national governance, low law enforcement capacity, low household wealth and health, and global elephant ivory prices. Forest elephant populations suffered higher rates of illegal killing than savannah elephants. We found only weak evidence that armed conflicts may increase the illegal killing of elephants, and no evidence for effects of site accessibility, vegetation density, elephant population density, precipitation or site area. Results suggest that addressing wider systemic challenges of human development, corruption and consumer demand would help reduce poaching, corroborating broader work highlighting these more ultimate drivers of the global illegal wildlife trade

A methodological approach for assessing cross-site landscape change: understanding socio-ecological systems

The expansion of agriculture has resulted in large-scale habitat loss, the fragmentation of forests, significant losses in biological diversity and negative impacts on many ecosystem services. In this paper, we highlight the Agrarian Change Project, a multi-disciplinary research initiative, that applies detailed socio-ecological methodologies in multi-functional landscapes, and assess the subsequent implications for conservation, livelihoods and food security. Specifically, the research focuses on land use impacts in locations which exhibit various combinations of agricultural modification/change across a forest transition gradient in six tropical landscapes, in Zambia, Burkina Faso, Cameroon, Ethiopia, Indonesia and Bangladesh. These methods include integrated assessments of the perceptions of ecosystem service provision, tree cover loss and gain, relative poverty, diets and agricultural patterns of change. Although numerous surveys on rural livelihoods are undertaken each year, often at great cost, many are hampered by weaknesses in methods and thus may not reflect rural realities. We attempt to highlight how integrating broader socio-ecological methods can be used to fill in those gaps and ensure such realities are indeed captured. Early findings suggest that the transition from a forested landscape to a more agrarian dominated system does not necessarily result in better livelihood outcomes and there may be unintended consequences of forest and tree cover removal. These include the loss of access to grazing land, loss of dietary diversity and the loss of ecosystem services/forest products

African Savanna herbivore communities: A model based on competition for food resources

Availability of food and its quality may be a strong influencing factor in structuring African ungulate communities in terms of species richness, dominance, and diversity. This hypothesis has been explored in several cross-sectional ecosystem comparison studies, but it has rarely been addressed in any modelling studies. As a consequence, a resource-based, multi-species model was developed to include a large variety of herbivore species feeding in a complex heterogenous landscape, demarcated by habitats of differing forage quality. The spatial distribution of herbivores across a landscape is assumed to follow that described by the ideal free distribution (IFD). Two analytical methods are developed to describe the distribution of individuals across a range of habitats of differing size and intrinsic quality. The quality of the habitat is determined from the feeding energetic of herbivores. The energy budget model incorporates the effect of body size and forage quality on digestive constraints of herbivores and the effect of resource abundance on grazing rate. Interspecific competition occurs in habitats that are shared due to collectively grazing on the same resource. Whereas, intra-specific competition is modelled as reducing the grazing rate of an individual because of interference effects from conspecifics. The system of equations to describe the community dynamics was solved numerically to produce vegetation and population trajectories. The model provides insight as to how food competition, vegetation abundance and quality, collectively influence the structure and dynamics of large mammal communities in the African savannas. In the model, self-limiting is one factor that allows for the coexistence of more species than there are resources or habitats. Finally, simulations were designed to explore the implication of food availability and its quality on structuring ungulate communities. The results of the simulation show that ungulate biodiversity peaks at intermediate productive sites and decreases at low and high productive sites. These and other model results are compared to findings from cross-sectional ecosystem comparison studies. An extension of the model to incorporate other factors such as grazing succession, predation, interseasonal variation in rainfall is briefly discussed.</p

Optimum bird flock size in formation flight

A theoretical model of flock size in migrating birds is developed. Although previous models of formation flight in birds show improved flight performance, they do not explain flock size variation across bird species or at different times of the year for a given bird species. This model captures some of the diversity in flock size observed in nature by incorporating energetic costs of flight and energy income from foraging. It turns out that within a myriad of possible flock sizes there - is one that is optimal for maximizing energetic efficiency (net energetic gain/energy expenditure) for a given maximum range speed, which minimizes flying cost per unit distance flown, and under certain migration conditions (i.e. flight distance and total time to complete the journey). Net energetic gain from foraging equals the rate of prey encountered times the time spent foraging. Energy expenditure from flying is determined from formation flight theory for a fixed wing aircraft. The benefit of formation flight, as derived from an approximation technique, is represented in close-form. This expression is a function of flock size and wing-tip spacing (WTS) and simplifies flight cost calculations. Under certain WTS, a good approximation to the induced drag for a member of a flock of size n is 1/nth of the induced drag of a single bird. In addition, optimum flight speed of a flock is (1/n)⅟₄ of the optimum flight speed of a single individual. The approach taken here allows the prediction of flock size in migrating birds. Model results are discussed in relation to observation of flock size under various migration conditions. If migration is constrained by hours of daylight, seasional variation in flock size is expected if the start time of the north and southward migration are asymmetrical with respect to the summer solstice (June 21). Under certain conditions, such as long non-stop migration, solo flight is an optimum migratory strategy.Science, Faculty ofZoology, Department ofGraduat

A Continuum Formulation of the Ideal Free Distribution and Its Implications for Population Dynamics

The ideal free distribution is a description of how organisms would distribute themselves in space if they were free to move so as to maximize fitness. The standard formulation of the ideal free distribution envisions the environment as consisting of finitely many discrete habitats. In this paper, a version of the ideal free distribution is derived for the case where the environment is a continuum. The continuum formulation allows computation of average fitness at the population level by taking account of both local fitness and the spatial distribution of the population. An example shows that the average fitness may have a different form than the local fitness; in particular, if local fitness is described by a logistic equation at each location, the average fitness may obey the θ-logistic equation of F. J. Ayala et al. (1973, Theor. Popul. Biol. 4, 331–356). This gives a mechanistic derivation of the θ-logistic equation