Recipient Organization
TEXAS A&M UNIVERSITY
750 AGRONOMY RD STE 2701
COLLEGE STATION,TX 77843-0001
Performing Department
Ecosystem Science & Management
Non Technical Summary
In the Southern Great Plains, as in many other regions of the globe, grasslands are being transformed into woodlands and shrublands--a phenomenon known as woody plant encroachment (WPE). The progression of WPE has far-ranging consequences for both human and ecological systems, because it alters the timing, flow, and distribution of ecosystem services (Stafford Smith et al. 2009, Archer et al. 2011, Matschullat et al. 2012). Nevertheless, WPE is neither well understood nor widely appreciated as a complex problem with both ecological and social dimensions.If we are to selectively preserve the grasslands that remain, and prioritize restoration where required, a new paradigm is needed for WPE: that it is a dynamic phenomenon, in which coupled biophysical and social processes operate and interact. This new understanding requires the development of frameworks that explicitly recognize (1) nonlinear responses and feedbacks within and between the biophysical and social dimensions; (2) threshold conditions that separate alternative social-ecological states; and (3) time-lag and legacy effects that delimit the scope of potential future outcomes (Araujo et al. 2003, Liu et al. 2007a, Liu et al. 2007b, Wells 2013).The concept of linked social-ecological systems enables us to understand complexity in dynamic systems--specifically, how ecological processes interact to affect social welfare and how social processes and individual behavior feed back to influence the ecological processes. Many cases of ecological change, driven by natural or social factors or their interaction, have negative effects on the availability of ecosystem services upon which human populations rely. The overall resilience of a social-ecological system is governed by these interactions and feedbacks, and therefore the challenge is how to effectively manage ecological processes in ways that maintain the delivery of desired ecosystem services within these constraints (Chapin et al. 2010, Folke et al. 2010).In drylands, WPE has been driven largely by the elimination of fire from the system--both because overgrazing has consumed most of the fine fuel needed to propagate fire and because of active fire suppression (Walker and Meyers 2004). Other factors that may be exacerbating WPE include the dissemination of woody-plant seeds by animals, increased atmospheric CO2 concentrations, and a warming climate--but these are secondary to changes in fire regime (Archer et al. 1995, Archer et al. 2001, Briggs et al. 2005, Naito and Cairns 2011).Efforts to contain the expansion of woodlands to date have been largely ineffective except in isolated areas where cultures promoted the use of prescribed fire (e.g., the Tall grass Prairie region of Oklahoma and Kansas). Through the rest of the study region, landowners attempted to "control" the proliferation of woody plants using a variety of approaches collectively known as "brush management." During the 1960s and '70s, public investment in brush management was a virtual "war on shrubs" aimed at eradication through mechanical and chemical methods (Bovey 2001). However, consistent with state-change theory, such interventions were short-lived (5-10 y) and hence ineffective. Since the 1980s, there has been a gradual recognition that to be economically feasible and ecologically effective, management interventions must take place before critical transition thresholds are crossed (Figure 2); that to conserve and restore grasslands, management systems must be based on decadal planning horizons; and that a realistic evaluation of the effectiveness of grazing and brush management practices will require an explicit accounting of ecosystem services (Archer et al. 2011, de Araujo et al. 2012). Although this evolution of perspectives has changed how managers and society view WPE, there is not yet a mechanism in place to apply these broader and more informed perspectives. The research we are proposing seeks to develop an ABM as an integrated framework and an approach for explicitly incorporating ecological, economic, and social facets of WPE, grazing, and brush management into that framework.
Animal Health Component
90%
Research Effort Categories
Basic
5%
Applied
90%
Developmental
5%
Goals / Objectives
Given the spatial scale of the grassland-to-woodland conversion that has already occurred in the Southern Great Plains and the inevitability of further conversion in the absence of major interventions, important goals are to (1) quantify the effects of WPE on ecosystems and the services they provide--specifically in regard to water and carbon; (2) assess the vulnerability of rural communities dependent on grassland and savanna ecosystems; (3) identify viable socio-ecological opportunities for using prescribed fire as a tool for maintaining and restoring grasslands; and (4) overcome existing barriers to collective action among landowners and policy stakeholders and facilitate the cooperation necessary to meet grassland conservation and restoration objectives.
Project Methods
To achieve these goals, I am collaborating with an interdisciplinary group of colleagues and initiating studies for comparing three ecoregions within the Southern Great Plains, each having a distinct social, cultural, and ecological history and a distinct trajectory with respect to WPE and society's response to it. These regions are (1) the Edwards Plateau in central Texas; (2) the Rolling Red Plains in north central Texas and western Oklahoma; and (3) the Tall Grass Prairie in northern Oklahoma and eastern Kansas (Figure 1). Our research will be informed through an iteratively developed, agent-based model (ABM) linked to land cover (Cury Fracetto et al. 2012). Agent-based models are well suited for investigating social-ecological issues because they are able to internalize and reproduce the key attributes, dynamics, and behaviors of complex systems. The ABM will be used to evaluate the outcome of interacting factors that affect landowner decision-making and decision outcomes with respect to using fire as a management tool; to forecast regional changes in woody plant cover under different land-use/management scenarios; and to project the effects of land-cover change (grasslands vs woodlands) on water resources (groundwater recharge and streamflow) and carbon storage.Collins et al. (2011) have proposed a theoretical framework to facilitate hypothesis formulation and testing related to social-ecological systems. This framework links the social and biophysical domains through continuous or episodic disturbances and ecosystem services. We have adapted this framework to conceptualize WPE in the Southern Great Plains as a social-ecological system (Figure 3) and to highlight components of that system that will be addressed in this project. Our primary land-management focus is the use of prescribed fire, but our modeling approach will address fire in the context of complementary or competing management options related to livestock grazing and chemical (herbicides) or mechanical brush management.I am convinced that it makes sense to organize research using the 7 hypotheses in this framework. By doing so it will enable us to develop approaches and modeling tools for (1) understanding WPE as a complex adaptive system with feedbacks, thresholds, nonlinear behavior, and emergent properties; (2) forecasting the rate of spread and extent of WPE under contrasting scenarios; and (3) evaluating the relative effects of policy options on landowner willingness to use prescribed fire as a management tool. My own work deals will focus on H1-H3 but my social science collaborators will focus on H4-H7. I elaborate more in the attached proposal.