Rangelands, pastoralists and governments: interlinked systems of people and nature

Abstract

We analyse commercially operated rangelands as coupled systems of people and nature. The biophysical components include: (i) the reduction and recovery of potential primary production, reflected as changes in grass production per unit of rainfall; (ii) changes in woody plants dependent on the grazing and fire regimes; and (iii) livestock and wool dynamics influenced by season, condition of the rangeland and numbers of wild and feral animals. The social components include the managers, who vary with regard to a range of cognitive abilities and lifestyle choices, and the regulators who vary in regard to policy goals.We compare agent-based and optimization models of a rangeland system. The agent-based model leads to recognition that policies select for certain management practices by creating a template that governs the trajectories of the behaviour of individuals, learning, and overall system dynamics. Conservative regulations reduce short-term loss in production but also restrict learning. A free-market environment leads to severe degradation but the surviving pastoralists perform well under subsequent variable conditions. The challenge for policy makers is to balance the needs for learning and for preventing excessive degradation. A genetic algorithm model optimizing for net discounted income and based on a population of management solutions (stocking rate, how much to suppress fire, etc.) indicates that robust solutions lead to a loss of about 40% compared with solutions where the sequence of rainfall was known in advance: this is a similar figure to that obtained from the agent-based model.We conclude that, on the basis of Levin's three criteria, rangelands with their livestock and human managers do constitute complex adaptive systems. If this is so, then command-and-control approaches to rangeland policy and management are bound to fail.

Global assessment of the non‐equilibrium concept in rangelands

“…Rangelands are dynamic ecosystems, with biomass, productivity, and herbivore numbers fluctuating through time O'Connor 2000, Gillson andHoffman 2007). These fluctuations can lead to various forms of degradation O'Connor 1999, Dregne 2002), affecting soil (Illius and O'Connor 1999), vegetation (Miehe et al 2010), wild fauna (Olff et al 2002), domesticated livestock, and subsequently, human livelihoods (Walker and Janssen 2002).…”

Impact of pastoral land use on central Namibian savanna vegetation - Methods for indictor development and perspectives for their application

“…Gegenstand von weideökologischen Untersuchungen sind immer gekoppelte soziale und ökologische Systeme (Walker & Janssen 2002). Sie sollten im Sinne einer möglichst ganzheitlichen Betrachtungsweise neben den natürlichen Gegebenheiten und biophysikalischen Prozessen auch die sozioökonomischen Rahmenbedingungen berücksichtigen (Hoffman et al 1999;Gillson & Hoffman 2007 (Reynolds et al 2007;Sommer et al 2011).…”

Complex Science for a Complex World : Exploring Human Ecosystems with Agents

“…In particular, agentbased models and computer-assisted reasoning show potential for gaining new insights into systems in which decisions are based on criteria with widely differing currencies, and where a multitude of individual decisions leads to emergent properties at a higher level (Levin 1998;Lempert 2002). We take a complex systems approach because these methodologies have already proved useful in exploring various aspects of rangeland dynamics (Janssen et al 2000;Anderies et al 2002;Walker and Janssen 2002;Janssen et al 2004). …”