Resistance & Resilience
Past practices, such as fire suppression, have created densely packed forests with an overabundance of woody vegetation. Live or dead, this vegetation can fuel severe wildfire. Overcrowded growing conditions also prevent trees and other plants from obtaining sufficient nutrients, light, or water to bounce back and remain healthy following a stressful event. The warming climate further stresses vegetation and can foster tinderbox conditions on the landscape, especially under widespread persistent drought.
This presentation discusses the following topics as they relate to rangelands:
- Resistance and Resilience are commonly used terms in discussions about agriculture and preparing for the future.
- Provide a common understanding of these terms as they apply to the ecology of grazed systems.
- Relationships between ecological resistance and resilience, disturbances, and ecological processes will be discussed.
Our findings suggest that all deserts exhibited vulnerability to increasing fire disturbance because relatively low soil seed densities may not provide enough propagules for revegetation. Therefore, seeding of these communities may be especially important. In the cold deserts, this susceptibility was further evidenced by the fact that aboveground community composition in fire-affected areas was significantly different from the nearby unburned community even 30 years after fire and burned communities were associated with non-native species. That said, native species did exist in seed banks of burned sites and some taxa, like Sporobolus sp., occurred in high densities. Therefore, caution may be needed when using herbicide treatments to control exotic species as there may be unintended consequences of decreasing desirable species. In contrast, our warm desert sites exhibited less change in terms of seed densities, species richness and aboveground community composition following fire. In the face of more frequent fires, the lack of shrub seeds in the seed bank of all deserts was notable and we found no evidence of greater seed densities or unique species assemblages associated with shrub microsites.
Assessing the geomorphic sensitivity of streams and the ecological resilience of riparian ecosystems provides the basis for understanding how they have responded to disturbances and management actions and how they are expected to respond in the future.
A collaborative group of managers and scientists led by Jeanne Chambers, research ecologist and senior scientist (emeritus) with the USDA Forest Service Rocky Mountain Research Station, and geomorphologist Jerry Miller, a professor of environmental science at Western Carolina University, developed a multiscale approach to help land managers rapidly assess watersheds and categorize them based on resilience and sensitivity to disturbance. The project was built on the long-term work of Chambers and her collaborators on Great Basin riparian ecosystems.
Results suggest that dry forest species are undergoing an active range shift driven by both changing recruitment and mortality, and that increasing temperatures and drought threaten the long-term viability of many of these species in their current range. While four of the five species examined were experiencing some declines, Pinus edulis is currently most vulnerable. Management actions such as reducing tree density may be able to mitigate some of these impacts. The framework we present to estimate range-wide demographic rates can be applied to other species to determine where range contractions are most likely.
Although important to consider in land management planning, abiotic properties cannot be directly influenced with management. In contrast, biotic properties of the ecosystem can be readily influenced by management. The formula for robust biotic resilience to wildfire and resistance to invasive annual grasses in the northern Great Basin sagebrush ecosystem is about maintaining and promoting perennial bunchgrasses. The management system must be resilient if we hope to promote ecosystem resilience in an ever-changing risk, seedling recruitment, and recovery environment. A successful strategy for promoting ecosystem resilience will require securing a resilient management system, and a shift in paradigm from random acts of opportunistic restoration to a sustained, organized, process-based approach for promoting ecosystem resilience.
We propose an integrated fire management approach in which all management activities before, during, and after wildfire are synergistic and improve long-term ecosystem response to fire. Harney County Wildfire Collaborative is adapting the Potential Operational Delineations (PODs) framework to improve fire outcomes and promote values at risk in the Stinkingwater Mountains pilot project area. The PODs framework serves to promote a broader geographic strategy for addressing the underlying causes of frequent and severe wildfires in the sagebrush ecosystem.
Multiple research and management partners collaboratively developed a multiscale approach for assessing the geomorphic sensitivity of streams and ecological resilience of riparian and meadow ecosystems in upland watersheds of the Great Basin to disturbances and management actions. The approach builds on long-term work by the partners on the responses of these systems to disturbances and management actions. At the core of the assessments is information on past and present watershed and stream channel characteristics, geomorphic and hydrologic processes, and riparian and meadow vegetation. In this report, we describe the approach used to delineate Great Basin mountain ranges and the watersheds within them, and the data that are available for the individual watersheds. It also describes the resulting database and the data sources. Furthermore, it summarizes information on the characteristics of the regions and watersheds within the regions and the implications of the assessments for geomorphic sensitivity and ecological resilience. The target audience for this multiscale approach is managers and stakeholders interested in assessing and adaptively managing Great Basin stream systems and riparian and meadow ecosystems.
View the report.
A new USDA Forest Service, Rocky Mountain General Technical Report on geomorphic sensitivity and ecological resilience of Great Basin streams and riparian ecosystems is now available. It provides the information needed to evaluate the sensitivity and resilience of Great Basin watersheds based on the characteristics of the streams and riparian ecosystems, determine how they are likely to respond to disturbance and management actions, and prioritize areas for conservation and restoration actions.
A website has been developed that provides an overview of GTR-426 and has downloadable, autofill forms for implementing the assessment.
View technical report.
This report assesses recent forest disturbance in the Western United States and discusses implications for sustainability. Individual chapters focus on fire, drought, insects, disease, invasive plants, and socioeconomic impacts. Disturbance data came from a variety of sources, including the Forest Inventory and Analysis program, Forest Health Protection, and the National Interagency Fire Center. Disturbance trends with the potential to affect forest sustainability include alterations in fire regimes, periods of drought in some parts of the region, and increases in invasive plants, insects, and disease. Climate affects most disturbance processes, particularly drought, fire, and biotic disturbances, and climate change is expected to continue to affect disturbance processes in various ways and degrees.