Introduction to Ecologically-Based Invasive Plant Management

Transcription

1 1 Module 1 Introduction to EBIPM 2 Introduction to Ecologically-Based Invasive Plant Management Learning Objectives 1. Recognize differences in traditional and ecologically-based approaches to invasive plant management, and why there is a need for an ecologically-based approach. Traditional approaches to deal with weed invasion have generally been ineffective. A major constraint in traditional approaches to invasive plant management is the lack of a useful decision-making process with an ecological basis that allows for prediction of vegetation dynamics in response to management (Sheley et al. 2010). Land managers have primarily relied on herbicides and other tools to control weeds (i.e., symptoms of invasion) without understanding why weeds invade, and often reinvade, wildland ecosystems. Enduring invasive plant management and ecosystem restoration can only be achieved if the underlying causes of invasion and associated ecological processes are identified and altered to direct successional dynamics toward a desired plant community. A set of general principles is also needed to help managers understand how various tools will modify ecological processes in different environments, as is an adaptive approach that promotes learning during management. Ecologically-based invasive plant management (EBIPM) is a step-by-step decision-making framework that allows managers to visualize and understand the linkages among site assessment, ecological processes, vegetation dynamics, guiding principles and management practices, and design and implement more effective weed management programs for any landscape (Figure 1.1). 2. Understand and be able to explain the individual steps in the Ecologically-based Invasive Plant Management (EBIPM) framework. This modular curriculum is designed for university students and instructors in weed science, invasion ecology, restoration ecology, and natural resource management courses. Each step in the EBIPM framework is covered in detail (Modules 2-6), as are the economic and policy aspects of invasive plant management (Module 7) and the use of seedbed microclimate/ plant establishment modelingto determine the success and cost-effectiveness of restoration strategies (Module 8). When students have a better understanding of EBIPM, they will be able to apply this knowledge in their future roles as land mangers and policy makers, and improve the condition of weed-infested public and private wildlands.

2 3 Module 1 Introduction to EBIPM 4 Step 4: Step 5: Design and Execute a Plan Using Adaptive Management Choose Appropriate Tools and Strategies Based on Principles Step 3: Use Principles to Guide Decision Making Step 1: Complete Rangeland Health Assessment The EBIPM model has been developed from successional theory and has been adapted and expanded since its introduction in 1996 (Sheley et al. 1996) to the present-day model (Sheley et al. 2010). Underlying successional theory comes from the work of MacArthur (1962), who proposed that species changes are associated with individual strategies: r-strategists, such as cheatgrass (Bromus tectorum), are rapid growing, shortlived, high seed producers adapted to distrubed sites, and K strategists, such as big sagebrush (Artemisia tridentata), Step 2: Identify Causes of Invasion and Associate Processes Not Functioning Figure 1.1: The EBIPM decision-making framework is based on successional theory. The framework consists of 5 steps which will be covered in greater detail throughout this section. To most effectively treat and manage weeds the framework should be adapted and repeated. are slower growing, perennial, low seed producers adapted to less disturbed sites (Figure 1.2). Pickett et al. (1987) proposed a hierarchical successional management framework. The first level of the hierarchy identifies three causes of succession: site availability, species availability, and species performance. The second level specifies the ecological processes that influence the three causes of succession. The final level describes site-specific, modifying factors that can alter ecological processes and ultimately influence Healthy sagebrush community Cheatgrass encroaching on sagebrush Cheatgrass-dominated community Figure 1.2: Succession from sagebrush community to cheatgrass monoculture. successional dynamics. Luken (1990) applied the successional management framework to natural resources management. Sheley et al. (1996) modified successional management for exotic plant invasions and suggested that plant communities dominated by invasive weeds could be restored by addressing the three causes of succession. Krueger-Mangold et al. (2006) provided an indepth description of the ecological processes influencing the causes of succession. Recently, the EBIPM model (Figure 1.3) has been expanded to include: 1) rangeland health assessment to determine ecological processes in need of repair (Pellant et al. 2005); 2) principles that link ecological process to management tools and strategies (James et al. 2010); and 3) adaptive management to encourage managers to learn by doing and make changes to their weed management plan based on findings from long-term monitoring (Reever-Morgan et al. 2006). EBIPM has been used to direct plant communities dominated by perennial weedy forbs toward desired native species (Sheley et al. 2006), and is currently being used for invasive annual grasses in the Great Basin.

3 5 Module 1 Introduction to EBIPM 6 Figure 1.3: Ecologically-based Invasive Plant Management decision-making framework.

4 7 Module 1 Introduction to EBIPM 8 Assessment of the current land situation identifes ecological processes which are in disrepair. Rangeland Health Assessment (RHA) uses qualitative observations to make assessments that are based on deviations from expected ecosystem conditions (Figure 1.4). RHA evaluates three attributes of rangeland health: 1. soil/site stability 2. hydrologic function 3. biotic integrity Figure 1.4: Managers completing the RHA will fill out a reference sheet and rank the indicators as extreme, moderate, slight, or no deviation from the standard found on the Ecological Site Description sheet. Different combinations of 17 indicators (e.g., plant community composition, bare ground, water flow patterns, litter amount, and invasive plants) are used to gauge the three ecosystem attributes. RHA has been linked to successional management in the EBIPM framework with a worksheet that aligns the 17 indicators with the three causes of succession, helping land managers determine the most important causes of succession and those ecological processes that are not functioning properly (See Module 2: Assessment).

5 9 Module 1 Introduction to EBIPM 10 There are three causes of succession: site availability, species availability, and species performance (See Module 3: Causes of Succession). Addressing the causes of succession in a weed management plan allows managers to direct succession in a desired trajectory. If the causes of succession and the assocated ecological processes are not addressed, managers are merely treating the symptoms of weed invasion. Site Availability is associated with the process of disturbance (natural or human-caused) (Figure 1.5). Disturbance opens up areas to new or different plants by altering the natural succession of plant communities. It changes the conditions of the soil, which can make it easier for seeds of invasive species to move in and establish. Disturbance can also alter the availability of resources (nutrients and water) for plants. Plant communities can be directed toward a more desirable state through altering these disturbances to favor germination, establishment and growth of native and desirable species. Examples of disturbance: WILDFIRE LIVESTOCK GRAZING EQUIPMENT INSECT INFESTATION Figure 1.5: Disturbance is the main process equipment, and insect infestation. Figure 1.6: Species availabilty is related to the processes of dispersal and reporduction. Species Availability is related to the processes of dispersal and reproduction (Figure 1.6). Dispersal depends on what species are present in the area and also nearby, and how well those species can spread into a given area. It is important to have viable propagules of desired plants present in the seed bank so these species can compete with the invasive species seeds. Seeding desired species can shift the community composition to a more desirable state. Species Performance is influenced by factors such as: the plant s life strategy, its ability to adapt to the environment, how it is by influenced by neighbors of different species, and how it captures and uses resources (Figure 1.7). Understanding what desired plants need to survive and grow in different environments will help managers be able to manipulate the landscape to a more desireable state. Figure 1.7: Species performance is influenced by stress, interference, response to environment, resource acquisition, and life strategy.

6 11 Module 1 Introduction to EBIPM 12 Ecological principles link managment tools and strategies to ecological processes influencing the causes of succession that drive plant community change (Figure 1.8). Principles also indicate the relative magnititude and direction of change that a management practice will likely have on invasive and desired plants. These ecological principles are based on naturally occurring processes, and were developed by synthesizing existing scientific literature (James et al. 2010). Each ecological principle provides an ecological objective for the manager to attain in order to repair a process and move the plant community toward a more desirable state. For more information see Module 4: Ecological Principles. In this step, tools and strategies are identified so that appropriate treatments can be developed. Ecological principles help managers determine the type, frequency, and intensity of the various treatment choices for the given resources available. Examples of tools and strategies affecting ecological processes and causes of succession include: creating disturbances (site availability), seeding desired species (species availability), and use of grazing or herbicides to shift the competitive balance between desirable and invasive plant species (species performance) (Figure 1.9). With a better understanding of the effects of tools and strategies on ecological processes, a manager can make informed decisions to promote desirable vegetation. For more information see Module 5: Tools and Strategies. Management tools and strategies modify Ecological processes drive Plant community change Examples of Tools and Strategies link Ecological principles indicate magnitude and direction of Figure 1.8:Ecological principles link tools and strategies to ecological processes (underlying the causes of succession) that drive plant community change, and indicate the magnitude and direction of change toward a more desirable community. Prescribed Herbicide Prescribed Seeding Desired Burning Application Grazing Species Figure 1.9: Tools and strategies used in a weed management plan must address the causes of succession and the associated ecological processes in disrepair. Examples of tools and strategies include: prescribed burning, herbicide application, prescribed grazing, and seeding desired species.

7 13 Module 1 Introduction to EBIPM 14 Evaluation Questions 1. What are the three causes of succession and how do they relate to weed invasion? Adaptive management helps managers make decisions in the face of uncertainty and to learn by doing. It is actually an overarching strategy involving all steps in the EBIPM decision-making framework. It is a process that involves formulating questions, choosing management techniques to test these questions and applying the techniques to the landscape using an experimental design. After treatments are applied to the site, monitoring data are collected and analyzed. The findings allow managers to determine if treatments have been successful or if they need to reassess their management plan. Regular monitoring is a necessary step in the adaptive management process. A control plot should also be set up, in accordance with the experimental design, as part of the management plan (Reever-Morghan et al. 2006). The use of adaptive management improves land managers decision-making over time and helps to create a management program that is more scientifically valid and economically feasible. 2. Explain the importance of using a decision-making framework, like EBIPM, to manage invasive weeds. Activity Read the journal articles Potential for successional theory to guide restoration of invasive-plant-dominated rangeland (Sheley et al. 2006) and Long-term effects of weed control with Picloram along a gradient of spotted knapweed invasion (Ortega & Pearson 2011). The article by Sheley et al. (2006) used an EBIPM approach, while the Ortega and Pearson (2011) did not use EBIPM. After reading the articles answer the following questions: 1. Did the studies use any kind of initial assessment? If not, how would you conduct an assessment in each study? 2. How were the causes of succession addressed in each study? 3. Can you think of any ecological principles that were used to determine which ecological processes were in need of repair, and which tools and strategies should be used to modify the processes? 4. Were these treatments effective in the short-term? In the long-term? 5. How can adaptive management be used in each study? How would you develop a long-term management and monitoring plan?

8 15 Module 1 To Learn More... EBIPM website Literature Cited James, J.J., B.S. Smith, E.A. Vasquez, & R.L. Sheley Principles for ecologically based invasive plant management. Journal of Invasive Plant Science and Management. 3: Krueger-Mangold, J.M., R.L. Sheley, & T.J. Svejcar Toward ecologically-based invasive plant management on rangeland. Weed Science 54: Luken, J Directing ecological succession. New York: Chapman and Hall. 250 pp. MacArthur, R.H Some generalized theorems of natural selection. Proc. Natl. Acad. Sci. 48: Ortega, Y.K. & D.E. Pearson Long-term effects of weed control with Picloram along a gradient of spotted knapweed invasion. Rangeland Ecology & Management 64: Pellant, M., P. Shaver, D.A. Pyke, and J.E. Herrick Interpreting indicators of rangeland health, version 4. Technical Reference U.S. Department of the Interior, Bureau of Land Management, National Science and Technology Center, Denver, CO. BLM/WO/ST-00/ /REV pp. Pickett, S.T.A., S.L. Collins, & J.J. Armesto Models, mechanisms, and pathways of succession. Bot. Rev. 53: Reever-Morghan, K.J., R.L.Sheley, & T.J. Svejcar Successful adaptive management- the integration of research and management. Rangeland Ecology & Management 60: Sheley, R.L., T.J. Svejcar, & B.D. Maxwell A theoretical framework for developing successional weed management strategies on rangeland. Weed Technology 10: Sheley, R.L., J.M. Mangold, & J.L. Anderson Potential for successional theory to guide restoration of invasive-plant-dominated rangeland. Ecological Monographs 76: Introduction to EBIPM 16 Sheley, R.L., J.James, B. Smith, & E. Vasquez Applying ecologically based invasive plant management. Rangeland Ecology & Management 63: Written by: Halley Kartchner, Chris Call The Area-wide project is a USDA-ARS funded program to encourage and support enduring invasive annual grass management throughout the Great Basin.