Interactions between human behaviour and ecological systems

Philosophical Transactions of the Royal Society B: Biological Sciences, Jan 2012

Research on the interactions between human behaviour and ecological systems tends to focus on the direct effects of human activities on ecosystems, such as biodiversity loss. There is also increasing research effort directed towards ecosystem services. However, interventions to control people's use of the environment alter the incentives that natural resource users face, and therefore their decisions about resource use. The indirect effects of conservation interventions on biodiversity, modulated through human decision-making, are poorly studied but are likely to be significant and potentially counterintuitive. This is particularly so where people are dependent on multiple natural resources for their livelihoods, when both poverty and biodiversity loss are acute. An inter-disciplinary approach is required to quantify these interactions, with an understanding of human decision-making at its core; otherwise, predictions about the impacts of conservation policies may be highly misleading.

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Interactions between human behaviour and ecological systems

E. J. Milner-Gulland * 0 0 Department of Life Sciences, Imperial College London , Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY , UK Research on the interactions between human behaviour and ecological systems tends to focus on the direct effects of human activities on ecosystems, such as biodiversity loss. There is also increasing research effort directed towards ecosystem services. However, interventions to control people's use of the environment alter the incentives that natural resource users face, and therefore their decisions about resource use. The indirect effects of conservation interventions on biodiversity, modulated through human decision-making, are poorly studied but are likely to be significant and potentially counterintuitive. This is particularly so where people are dependent on multiple natural resources for their livelihoods, when both poverty and biodiversity loss are acute. An inter-disciplinary approach is required to quantify these interactions, with an understanding of human decision-making at its core; otherwise, predictions about the impacts of conservation policies may be highly misleading. 1. INTRODUCTION The theme of this issue of the journal is predictive systems ecology. However, in order to be truly predictive in any human-altered environment, the system under consideration must include human users, and this requires the integration of ecology with social science. In this paper, I focus on the potential for closer integration of ecology and social science in order to improve the predictive power of system dynamics models. I draw my examples primarily from conservation science, with an emphasis on guiding the implementation of policies aimed at improving the sustainability of natural resource use. Traditional ecological studies addressing the effects of human activities on ecosystems include a body of literature on the sustainability of direct resource exploitation, and other major literatures on the effects of by-products of human activity, such as pollution, habitat destruction and climate change. The overexploitation literature has moved in recent years from a concern with the sustainability of particular levels of harvest mortality, in terms of the population trends of the species being harvested, to a wider concern about ecosystem effects of harvesting, and a more nuanced understanding of the heterogeneity of harvesting effects between species and locations. For example, much work in the 1970s focused on how best to manage fisheries to maintain stocks above a target level [1,2]. Broadening the scope to multi-species fisheries, in the 1990s, authors such as Roberts [3] highlighted the phenomenon of fishing down the food chain such that smaller species at lower trophic levels appeared in the catch as larger predatory fish were depleted. Nowadays, the ecosystem approach to fisheries management is embedded in national legislation (e.g. the USAs Magnuson Stevens act; [4]) and the challenge is to operationalize this concept [5,6]. At the broader scale, there is increasing attention to predicting the effects of human activities on biodiversity and on particular species groups, difficult because of the likely threshold or nonlinear nature of their response to stressors. For example, climate models predict that the Amazon rainforest is likely to suffer substantial and rapid die-back beyond a climate threshold [7,8], while there is a threshold pH beyond which marine organisms are unable to sequester calcium for their exoskeletons from seawater [9]. Meta-population persistence is also a threshold process depending on the size, quality and configuration of habitat patches [10]. Different processes may lead to different abundance trends for the species concerned, some more linear than others [11]. The ecosystem services research field takes the other side of the equationhow do changes in natural systems feed through to changes in human well-being (as defined by the Millenium Ecosystem Assessment (MEA) [12])? Several steps are required in order to quantify this contribution; firstly, there needs to be an understanding of how changes in human activities impact the dynamics of ecosystems, then how these changes in ecosystem structure, function and diversity affect the range of services that humans use and then how changes in these services feed through into well-being. The metrics at each stage are not straightforward to define and the processes involved are not easy to quantify [13]. This is a very active area of research, following the lead of the MEA [14]. Few people have followed the chain of reasoning right through from changes in management to changes in well-being, with a rare example being Black ([15]; figure 1). She asked land managers in the UKs North Pennines Area of Outstanding Natural Beauty how they would respond to various scenarios of change, including changes in government policy and economic circumstances. For example, in one scenario, consistently low income (...truncated)


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E. J. Milner-Gulland. Interactions between human behaviour and ecological systems, Philosophical Transactions of the Royal Society B: Biological Sciences, 2012, pp. 270-278, 367/1586, DOI: 10.1098/rstb.2011.0175