SPECIAL FEATURE: SUSTAINABILITY ON THE U.S./MEXICO BORDER Iterative driver-response dynamics of human-environment interactions in the Arizona-Sonora borderlands 1,2, 1 CHRISTOPHER A. SCOTT AND STEPHANIE J. BUECHLER 1School of Geography & Development, University of Arizona, Tucson, Arizona 85721 USA 2Udall Center for Studies in Public Policy, University of Arizona, Tucson, Arizona 85721 USA Citation: Scott, C. A., and S. J. Buechler. 2013. Iterative driver-response dynamics of human-environment interactions in the Arizona-Sonora borderlands. Ecosphere 4(1):2. http://dx.doi.org/10.1890/ES12-00273.1 Abstract. In complex social-ecological systems, human and physical processes mutually condition one another through co-adaptation at multiple scales from the local to the global. For this paper we modified a driver-response conceptual model of social-ecological interactions by considering the degree to which each binary set of processes (human or physical) is simultaneously a driver and a response to global change. Processes that we understood to be mutually conditioned offered greater potential compared to solely social or ecological communities to adapt to demographic and economic change, on the one hand, and to climate, water resources, and ecosystems dynamics, on the other. By considering case material from the United States–Mexico border region, we characterized social-ecological interactions along a continuum from those acting exclusively as drivers to others reacting to change primarily as responses. We considered water resources to integrate multiple global change processes including climate change and variability, ecosystem resilience, and human water demands for a variety of purposes. Thus, we examined in detail two watersheds in the Arizona–Sonora borderlands representing mutually conditioned social-ecological systems. First, the Rı´o Magdalena in Sonora represented an illustrative case of smallholder agriculture and rural livelihoods engaged in social-ecological interaction that exhibited both driver and response elements centered on reflexive, low-impact adaptive strategies. Second, in Ambos Nogales relying on the Santa Cruz River and its associated aquifers, urban growth, the equity of water access for human purposes, and environmental quality represented especially pressing challenges. Here, human impacts on ecosystems were the predominant drivers although there was growing concern for the medium- and longer-term implications of climate change. Adaption planning in Ambos Nogales was centered on infrastructure- based solutions including an inter-basin water transfer connection with the Rı´o Magdalena. Wastewater flows to riparian corridors posed a particular challenge for human-environment interactions. Cross-border collaboration represents an important opportunity for adaptation based on the mutually conditioned interactions presented here. We summarized the analysis of both cases by raising conceptual questions for further enquiry and for adaptation and planning that are generic for the borderlands and beyond. Key words: adaptation; human-environment interactions; livelihoods; social-ecological systems; Special Feature: Sustainability on the U.S./Mexico Border. Received 29 August 2012; revised 13 November 2012; accepted 14 November 2012; final version received 13 December 2012; published 10 January 2013. Corresponding Editor: D. P. C. Peters. Copyright: Ó 2013 Scott and Buechler. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits restricted use, distribution, and reproduction in any medium, provided the original author and sources are credited. E-mail: [email protected] v www.esajournals.org 1 January 2013 v Volume 4(1) v Article 2 SPECIAL FEATURE: SUSTAINABILITY ON THE BORDER SCOTT AND BUECHLER INTRODUCTION rapidly, while broader contextual processes can influence coupled systems over the long term. Human societies and ecosystems are insepara- Third, the iterative functioning of human-ecosys- bly connected. Their interactions are dynamic, tem interactions can modify responses and make non-linear, and exhibit threshold behaviors. them act as drivers in sequential fashion. These Because both humans and ecosystems anticipate feedbacks can lead to unique system trajectories change and respond to drivers, coupled systems resulting from the co-adaptation of human and have memory. This does not lead to deterministic natural components of coupled systems. Fourth, outcomes but strongly shapes system behavior the combination of the first three characteristics through internal dynamics. The drivers of change (mutual conditioning, multi-scalar dynamics, can originate within coupled systems or exoge- and iterative effects) offers opportunities for nously, a result of mutual influences between adaption to global change. Based on this coupled human and ecosystem processes occurring at a system perspective, global change is understood range of spatial and temporal scales. Cross-scale to encompass climate and earth systems process- influences of human and natural processes and es as well as demographic and economic change. the variable timeframes over which they operate Our conceptual approach draws from resil- can set up sequentially evolving driver-response ience theory (Gunderson and Holling 2002, dynamics. An important goal of this paper is to Walker and Salt 2006, Gunderson et al. 2010) demonstrate, conceptually and empirically, that and social-ecological systems understandings of drivers can become responses, and vice versa. human-environment interactions (Scheffer et al. A definition is in order before we proceed. 2002, Ostrom 2007). Here we refer to social- Human-environment interactions (HEI, as re- ecological systems by the acronym SES. Global ferred to in this paper) may broadly be charac- change as described by geographers Leichenko terized along a continuum from environmental and O’Brien (2008) and Eakin (2006) must be determinism, on one extreme, to the primacy of expanded to more fully capture the iterative, co- human agency, on the other. At the first extreme, adaptive and often cyclical responses of long- physical processes are understood to occur term HEIs. Leichenko and O’Brien and Eakin independently of human influence and exert developed and applied the concept of ‘double impacts on individuals and societies. Examples exposure’ that sheds light on the complex include events such as hurricanes and earth- linkages between economic globalization and quakes, which cause serious damage globally. climatic change particularly as they act in concert The origin of these physical processes is not to shape contexts of vulnerability for populations influenced by human activity, although their such as small-scale farmers. However, the cycli- intensity and frequency may be, and the severity cal, iterative conceptualization of HEI processes of their impact clearly is—a point we will return originates in ecology. For example, Levin (1999) to. At the other extreme, human activity produc- referred to management (i.e., human) and eco- es a range of environmental impacts. For system dynamics as adaptive and, ultimately, instance, mining and extractive energy resource ‘‘self-organizing.’’ In an analogous manner, development result in habitat loss and threats to Chetkiewicz et al. (2006) described the crucial biodiversity. At both ends of the HEI continuum, explanatory value of process (i.e., dynamics) to causality and impact are seen as unidirectional. understand human-wildlife interactions inherent Here we seek to identify and describe four in more static landscape pattern. principal characteristics of coupled natural-hu- As will be seen below, by inverting the driver- man dynamics. First, human and ecosystem response relationship, we add explanatory value processes are mutually conditioned, that is, to coupled systems dynamics. Additionally, human activity is influenced by environmental when system dynamics cross thresholds—those conditions while ecosystem processes react to critical junctures of crisis, collapse, and reorgani- and internalize resources resulting from human zation as conceptualized by the adaptive cycle activity. Second, human-ecosystem interactions (Gunderson and Holling 2002)—ecosystem pro- operate at a range of spatial and temporal scales. cesses allow species to recruit resources released Localized driver-response cycles tend to occur through collapse, while analogously social and v www.esajournals.org 2 January 2013 v Volume 4(1) v Article 2 SPECIAL FEATURE: SUSTAINABILITY ON THE BORDER SCOTT AND BUECHLER Fig. 1. The Arizona-Sonora Borderlands. institutional processes give rise to heightened Numerous instances of HEIs are found in the human innovation and experimentation during region. For contextual purposes, we briefly reorganization phases (McLaughlin and Dietz characterize several examples that help illustrate 2008, Young 2010). We apply our conceptual the range of conditions encountered, even approach to the United States – Mexico border, though they are not the principal focus of our specifically to the Sonoran Desert region shared analysis. Subsequently, we explore two cases by the states of Arizona in the U.S. and Sonora in from the ASB region in greater detail. In each, Mexico (Morehouse et al. 2007, Scott et al. 2008, our conceptual propositions draw from resilience Buechler 2009a, Serrat-Capdevila et al. 2009, Scott theory that we link to the evidence presented in and Pasqualetti 2010) as shown in Fig. 1. In this the