Kathleen A. Galvin

Energy Extraction and Use in a Nomadic Pastoral Ecosystem

An analysis of annual energy flows in an arid tropical ecosystem inhabited by nomadic pastoralists provides insight into a subsistence life-style that has persisted in droughted environments for hundreds to thousands of years. Although a large fraction of the total energy consumed by the Ngisonyoka of Kenya followed a single pathway from plant to animal to human, they also harvested solar energy from a relatively diverse assemblage of energy flow channels. Energy utilization and conversion efficiencies were generally low, as the system is maintenance-rather than production-oriented. Energy flow to maintenance must be relatively high to support biotic responses that enable tolerance of abiotic variability and to stabilize energy flow under the stress of severe droughts. Energy utilization by the Ngisonyoka is therefore consistent with ecological patterns that promote rather than diminish ecological stability under stress.

Climate patterns and land-use practices in the dry zones of Africa

Comparative regional analysis of Africa provides insights into the effects of climatic variation on land use. This information can be used to predict effects of future climatic change. This article discusses the following two areas in depth: precipitation patterns and land use including temporal precipitation patterns, seasonality, interannual variability, and long term trends; Seasonality, interannual variability and land use including agriculture and range vegetation and pastoralism. Numerous examples are presented. The authors conclude by integrating the regional information with global predictions and the problems of interactions among climate, ecosystems, land use and human culture. 80 refs., 6 figs.

Integrated modeling of land use and cover change

Local and regional land us and land cover change is an important ingredient in the larger problem of global environmental change. This article presents a conceptual scheme for applying an integration strategy to agricultural land use on the US great plains. The authors indicate that existing models should be linked and then modified with new algorithms for sociocultural behavior. The article evaluates the state of land use studies and models, offers a conceptual schematic for integrated analysis, and suggest ways to implement the conceptual models using existing simulation models. A regional context is provided by drawing on previous research into agricultural land use on the US Great Plains. 50 refs., 1 fig.

Nutritional ecology of pastoralists in dry tropical Africa

African pastoralists inhabit a variety of environments within tropical arid to semiarid regions. Ecological and cultural factors as well as economic opportunities and constraints influence the amounts and types of foods available. The preferred staple of all pastoral populations is milk from livestock. Pastoral diets are low in energy, but apparently adequate in protein. Growth in children is slow until late adolescence when height approaches the 50th percentile of reference data. Adult pastoralists are correspondingly tall and lean. Maintenance of high human numbers within the economy is a common strategy among a variety of pastoralists. The result is that pastoralists appear to be near the lower threshold of reasonable nutritional status at most times. This occurs despite marked variation in such elements as livestock and human numbers, diet composition, and activity patterns.

Evolution of models to support community and policy action with science: Balancing pastoral livelihoods and wildlife conservation in savannas of East Africa

We developed a “continual engagement” model to better integrate knowledge from policy makers, communities, and researchers with the goal of promoting more effective action to balance poverty alleviation and wildlife conservation in 4 pastoral ecosystems of East Africa. The model involved the creation of a core boundary-spanning team, including community facilitators, a policy facilitator, and transdisciplinary researchers, responsible for linking with a wide range of actors from local to global scales. Collaborative researcher−facilitator community teams integrated local and scientific knowledge to help communities and policy makers improve herd quality and health, expand biodiversity payment schemes, develop land-use plans, and fully engage together in pastoral and wildlife policy development. This model focused on the creation of hybrid scientific−local knowledge highly relevant to community and policy maker needs. The facilitation team learned to be more effective by focusing on noncontroversial livelihood issues before addressing more difficult wildlife issues, using strategic and periodic engagement with most partners instead of continual engagement, and reducing costs by providing new scientific information only when deemed essential. We conclude by examining the role of facilitation in redressing asymmetries in power in researcher−community−policy maker teams, the role of individual values and character in establishing trust, and how to sustain knowledge-action links when project funding ends.

Global Significance of Extensive Grazing Lands and Pastoral Societies: An Introduction

More of the land surface of the earth is used for grazing than for any other purpose (FAO 1999, WRI 2000, Asner et al. 2004, Ojima and Chuluun, Chapter 8). Although livestock and wildlife graze in forests and woodlands, we focus here on the lands where most herding peoples and their livestock graze: in ‘open’ grazing lands, which include savannas, grasslands, prairies, steppe, and shrublands (Asner et al. 2004). These grazing lands cover 61.2 million km or 45% of the earth’s surface (excluding Antarctica), 1.5 times more of the globe than forest, 2.8 times more than cropland and 17 times more than urban settlements (see Figure 1-1). These lands range from extremely dry (hyper-arid) to very wet (humid) and represent 78% of the land area grazed by livestock (Asner et al. 2004). Extending from the

Quantifying declines in livestock due to land subdivision

Abstract In Kajiado District, Kenya, ranches held communally by Maasai are being subdivided into individually owned parcels. Livestock owners know that herds on parcels that are too small cannot be viable, but the decline in the capacity of parcels to support livestock has not been quantified. We used ecosystem modeling to represent the effects of subdivision as Maasai group ranches were divided into 196, 10, 5, 3, and 1 km2 parcels. Within the spatially explicit, process-based Savanna ecosystem model, we used maps that constrained the movements of livestock to be within parcels. We also modeled cooperative grazing associations, giving groups of herders access to parcels composed of dispersed or contiguous 1 km2 parcels. Vegetatively productive areas had higher carrying capacities when isolated because resident animals did not compete with animals moving in seasonally from other areas. In a ranch of low but heterogeneous productivity, we saw a steady decline in capacity under subdivision, until 25% fewer livestock could be supported on the ranch of 1 km2 parcels relative to the intact ranch. On a ranch with both low productivity and heterogeneity, 20% fewer livestock were supported when parcels were still 10 km2. The most productive ranch studied saw small population changes with subdivision. Participation in grazing associations was helpful in the ranch intermediate in productivity and heterogeneity, but not other ranches. Subdivision of Kajiado lands might be inevitable, but our results show the relative benefits to stakeholders if land owners and policy makers act to maintain open or flexible access to individually held parcels.

Climate variability and impacts on east African livestock herders: the Maasai of Ngorongoro Conservation Area, Tanzania

East African pastoral adaptation and vulnerability to climate variability and climate change is assessed, using data from decisionmaking processes and ecological data of the Maasai of Ngorongoro Conservation Area as an example. The paper uses integrated modeling, linking PHEWS, a household model, to SAVANNA, an ecosystem model to look at the effects of drought and a series of wet years on the well-being of Maasai pastoralists. Model results suggest that the ecosystem is quite resilient and suggests that the Maasai of the NCA are not very vulnerable to climate variability. However the economic situation in the NCA is precarious and food insecurity is prevalent without drought. The result is that drought has a very negative effect on people.

An agro-pastoral household model for the rangelands of East Africa

Abstract East Africa contains areas with some of the greatest large mammal biodiversity on the planet. These areas are key natural resources for the economic development of the region. They are also key areas for pastoralists who have co-existed with wildlife for millennia. Increasing populations, conflicts between wildlife and cattle, and the growth of agriculture, are all placing great pressure on these lands This paper describes the development of a pastoralist socio-economic model that is linked to the Savanna ecosystem model. In this way, options and scenarios could be investigated for their impacts not only on the ecosystem but also on pastoralist households and their welfare. The model, named PHEWS (Pastoral Household and Economic Welfare Simulator), tracks the flow of cash and dietary energy in pastoralist households using a simple set of rules. The model was calibrated for the Ngorongoro Conservation Area (NCA), northern Tanzania. The results of two population increase scenarios are presented. Model results indicate that all households in NCA depend to some degree on outside sources of calories, and that pastoralist welfare in NCA, even with small amounts of agriculture allowed, is under severe pressure at current human population levels. Strengths and weakness of the model are discussed, and next steps in its application identified.

Understanding Human–Landscape Interactions in the “Anthropocene”

This article summarizes the primary outcomes of an interdisciplinary workshop in 2010, sponsored by the U.S. National Science Foundation, focused on developing key questions and integrative themes for advancing the science of human–landscape systems. The workshop was a response to a grand challenge identified recently by the U.S. National Research Council (2010a)—“How will Earth’s surface evolve in the “Anthropocene?”—suggesting that new theories and methodological approaches are needed to tackle increasingly complex human–landscape interactions in the new era. A new science of human–landscape systems recognizes the interdependence of hydro-geomorphological, ecological, and human processes and functions. Advances within a range of disciplines spanning the physical, biological, and social sciences are therefore needed to contribute toward interdisciplinary research that lies at the heart of the science. Four integrative research themes were identified—thresholds/tipping points, time scales and time lags, spatial scales and boundaries, and feedback loops—serving as potential focal points around which theory can be built for human–landscape systems. Implementing the integrative themes requires that the research communities: (1) establish common metrics to describe and quantify human, biological, and geomorphological systems; (2) develop new ways to integrate diverse data and methods; and (3) focus on synthesis, generalization, and meta-analyses, as individual case studies continue to accumulate. Challenges to meeting these needs center on effective communication and collaboration across diverse disciplines spanning the natural and social scientific divide. Creating venues and mechanisms for sustained focused interdisciplinary collaborations, such as synthesis centers, becomes extraordinarily important for advancing the science.