Resilience-based Ecosystem Management
Resilience-based management focuses on ecological processes, disturbances, management actions and land-use policies that affect system vulnerability and proximity to thresholds, rather than solely on threshold identification. This approach provides greater opportunities to incorporate adaptive management by monitoring ecological indicators describing the direction and rate of change in ecosystem resilience relative to pending thresholds. Long-term (> 25 yrs) vegetation records throughout the Great Plains, western US, and southern Canada are being used to evaluate resilience theory and to inform construction of state-and-transition models. Analyses of these records indicate that criteria describing the frequency, magnitude, directionality and temporal scale of community transitions may provide greater insight into both resilience theory and its application to ecosystem management. Resilience-based management provides opportunities to broadly guide system change to support ecosystem services and human livelihoods in a dynamic and certain future.
Human Dimensions of Rangeland Systems
Applied ecological disciplines are attempting to reconcile discrepancies between management (local) and scientific knowledge regarding natural resource management. The rotational grazing debate represents one such discrepancy in the rangeland profession. Research is being conducted to examine the origins of the rotational grazing debate, identify the major reasons for its persistence, and recommend ways to reconcile the debate. This requires a candid assessment of the nature and limits of scientific knowledge; reevaluation of the relationships between science, management and policy; and a model of science and management that is more inclusive of the human dimensions of rangelands. A limited understanding of the contribution of adaptive management with varying management intensities represents a major omission and source of confusion on this issue. An adaptive management framework that explicitly integrates both the social and ecological components of rangeland systems is required to effectively facilitate site-specific management strategies. A vision of collective ownership for natural resource challenges among academic, land management, and policy making institutions is necessary to promote greater development of policy–relevant science.
Climate Change in Warm, Temperate Savanna
The potential consequences of climate change on southern savannas are being investigated in an experimental field facility on the Texas A&M campus. This facility has the capacity to simulate precipitation distribution and warming both independently and in combination in field conditions which provides a novel research platform to evaluate the mechanisms underpinning ecosystem responses to climate change. Precipitation distribution is altered with permanent rainout shelters and overhead irrigation systems and warming is provided with overhead infrared lamps. Research emphasizes linkages between plant traits and carbon and nitrogen fluxes and the importance of competitive plant interactions in mediating ecosystem responses to climate change. The C4 grass little bluestem (Schizachyrium scoparium) will likely continue to occupy the savanna understory, but regeneration of post oak (Quercus stellata) may be reduced in future climatic conditions. Drought tolerance and increased growth in response to warming, especially in the spring, indicates an accelerated expansion of eastern red cedar (Juniperus virginiana) in response to projected warmer, drier climates in the south central US.
Vulnerability and Adaptation to Climate Change
Recent climatic trends and projections indicate continued directional change and increasing variability in climate that will influence both the ecosystem services and livelihoods derived from rangelands. This unprecedented challenge requires a comprehensive assessment of the vulnerability of social-ecological systems, including exposure, sensitivity and adaptive capacity, to climate change. Four ecoregions in western North America will be evaluated to accommodate the geographic variability of exposure to climate change. Sensitivity will estimated through the impacts of the projected exposures on ecological and social systems, especially those components and interactions affecting human livelihoods. Adaptive capacity will be assessed by surveying the successes and failures of previous and current adaptions to climatic variability, and by identifying both barriers and incentives for future adaption. This assessment is intended to enhance recognition and prioritize actions to contend with the emerging consequences of climate change by informing research agendas, promoting social learning networks, and alerting policy makers to potential vulnerabilities of North American rangelands to climate change.