MANAGEMENT OF INVASIVE PLANTS IN THE WESTERN USA
  • Defining the Problem
    • What is a Weed? >
      • Federal Definitions of Noxious Weeds
    • Costs of invasive plants
    • Human Factor
    • Challenges of Invasive Plants
    • Wildfires in the Western USA >
      • Forest Fires: Structure
      • Bark Beetles & Forest Ecosystems
      • Rangeland Fires
    • Climate Change Impacts on Plants >
      • Climate Change: CO2, NO, UV, Ozone Impacts on Plants
      • Climate Change Impacts on Crops
      • Climate Change Impacts on C4 Plants
      • Climate Change Impacts on Rangeland
    • What are we doing?
  • Focus of this Project
    • Why Western States? >
      • Audience for these reports
    • History: Are we doomed to repeat it? >
      • Dust Bowl Re-visited >
        • China: Past & Present
        • UN Biodiversity Report
    • Policy vs. Practice
    • Ecosystems & Economics >
      • Reductionist Approach to science
      • Ecology & Feminism
      • Systems View of Life
      • Ecosystems Health
      • Economic Growth
      • Impact of the Petrochemical Industry
      • Interrelation of Economics & Ecology
    • Federal Agencies >
      • Federal Agencies and Invasive Species
      • History of Coordination with States
      • Challenges of Coordination between Federal Agencies
      • Collaboration or Confusion
    • Organizations to assist landowners
    • Federal Legislation on Invasive Species >
      • 1930s Federal Laws on Invasive Species
      • Federal Seed Act 1939
      • 1940s-1960s Federal Laws on Invasive Species
      • 1970s Federal Laws on Invasive Species
      • 1980s Federal Laws on Invasive Species
      • 1990s Federal Laws on Invasive Species
      • 2000-2010 Federal Laws on Invasive Species
      • 2011-2022 Federal Laws on Invasive Species
      • Federal Bills on Invasive Species not passed
      • Executive Orders on Invasive Species
      • Federal Excise Taxes
    • State Laws and Lists of Noxious Weeds
    • My Inspirations
  • Why we need plants
    • Native Plants
    • Plant Resources
  • Invasive Success Hypotheses
    • Unified Framework
    • Role of Diversity >
      • How Ecosystems Maintain Diversity
      • Fluctuation Dependent Mechanisms
      • Competition-based coexistence mechanisms
      • Niche Differences
      • Species Richness
    • Enemy Release Hypothesis
    • Constitutive Defense Mechanisms
    • Evolution of Increased Competitive Ability
    • Role of Microbes
    • Indirect Defense Mechanisms
    • Novel weapons hypothesis
    • Evolutionary Shifts
    • Resource Allocation
    • Evolutionary Dynamics >
      • Pre-introduction evolutionary history
      • Sampling Effect
      • Founder Effect
      • Admixture, hybridization and polyploidization
      • Rapid Evolution
      • Epigenetics
      • Second Genomes
    • Role of Hybridization
    • Role of Native Plant Neighbors
    • Species Performance
    • Role of Herbivory
    • Evolutionary Reduced Competitive Ability
    • Summary Thoughts on Research
  • Historical Record
    • Regional Conferences
    • Timeline
  • Innovative Solutions
    • Agricultural Best Practices >
      • Ecologically based Successional Management
      • Perennial Crops, Intercropping, beneficial insects
      • Soil Solarization
      • Natural Farming
      • Permaculture
      • Organic Farming
      • Embedding Natural Habitats
      • Conservation Tillage
      • Crop Rotation
      • Water Use Practices
      • Tree Planting: Pros & Cons
    • Grazing Solutions >
      • Sheep and Goat Grazing
      • Cattle & Sheep Grazing
      • Cattle and Bison Grazing
      • Grazing and Revegetation
    • Rangeland Restoration >
      • Federal Goals for Rangelands
      • Novel Ecosystems
      • Prairie Restoration >
        • Prairie Restoration Workshop
        • Weed Prevention Areas
        • California grassland restoration
        • Selah: Bamberger Ranch Preserve
      • Sagebrush Steppe Restoration >
        • Low Nitrogen in Sagebrush Steppe
      • Revegetation with Native Plants
      • Dogs as detectors of noxious weeds
    • Nudges
  • Biological Control
    • Insects as Biocontrol >
      • Impacts of Biocontrol Agents on Non-Target Species
      • Indirect Impact of Biocontrol on Native Species
    • Challenges of Using Biocontrols >
      • DNA studies on Biocontrol Insects
      • Biocontrol takes time
    • Prioritization process for Biocontrol Programs
    • Evolutionary changes impact Biocontrol
    • Vertebrates as Biocontrol Agents
  • Herbicides: History and Impacts
    • Effectiveness of Herbicides in Agricultural Lands
    • Effectiveness of Herbicides in Rangelands
    • History of Use of Herbicides and Pesticides Prior to and During WWII
    • Herbicide use during and post-World War II >
      • 2,4-D Herbicide Use
      • 2,4-D and 2,4,5-T, post-World War II
    • Modern use of Herbicides >
      • Atrazine Herbicide
      • Dicamba Herbicide
      • Glyphosate Herbicide
      • Paraquat Dichloride
      • Picolinic acid family of herbicides >
        • Picloram (Tordon 22K) Herbicide
        • Triclopyr Herbicide
    • Herbicide Resistance in Invasive Plants >
      • Herbicide Resistant Crops
      • Controlling herbicide-resistant weeds in herbicide-resistant crops
      • Best Management Practices
    • Myth of the Silver Bullet
    • Myth of Eradication
    • Merging of Agrochemical Companies
    • Impacts of Pesticides on Environment and Human Health >
      • Pesticide Drift
      • Impacts of Pesticides on Biological Diversity
      • Impacts of Herbicides on Native Plants
      • Pesticide Impacts on Insects >
        • Butterflies: The Impacts of Herbicides
        • Monarch Butterflies: Impacts of Herbicides
      • Impacts of Pesticides on Wildlife >
        • Reptiles & Amphibians: Pesticide Impacts
      • Pesticide Residue in Foods
    • Funding for Research on Pesticides
    • Commentary on Herbicide Use
  • Interviews
    • Interviews Biocontrol >
      • Biocontrol Wyoming
      • Montana Biocontrol Interview Maggio
      • Montana Biocontrol Interview Breitenfeldt
    • California Interviews >
      • Robert Price
      • Doug Johnson
    • Colorado Interviews >
      • George Beck Interview
      • Scott Nissen Interview
    • Idaho Interviews >
      • Purple Sage Organic Farms in Idaho
    • Montana Interviews >
      • Jasmine Reimer Interview Montana
      • Organic Farms Montana Interviews
    • Texas Interviews
    • Washington Interviews >
      • Ray Willard
    • Wyoming Interviews >
      • Slade Franklin Interview
      • John Samson Interview
    • Wyoming Weed and Pest Districts >
      • Josh Shorb Interview
      • Slade Franklin Interview 2
      • Lars Baker Interview
      • Steve Brill Interview
      • George Hittle Interview
      • Peter Illoway Interview
      • Robert Jenn Interview
      • Sharon Johnson Interview
      • Larry Justesen Interview
      • Gale Lamb Interview
      • Stephen McNamee Interview
      • Allen Mooney Interview
      • Rob Orchard Interview
      • Robert Parsons Interview
      • Dick Sackett Interview
      • Comments by Delena
    • NRCS Interviews: Wyoming
  • Western Weed Control Conference 1940s Minutes
    • 1942 Conference
    • 1945 Conference
    • 1946 Conference
  • Who am I?
    • My Work
    • My Adventures
    • Contact Page
  • Road Logs
    • Colorado Road Logs
    • Idaho Road Logs
    • Montana Road Logs
    • New Mexico Road Logs
    • Texas Road Logs
    • Wyoming Road Logs
  • Bibliography

Federal Goals for Rangelands,
​including Forests

 Photo: Muskox in tundra, north of the Arctic Circle, Alaska. © 2002 Delena Norris-Tull

NRCS Goals

Conservation Goals of IPM on rangelands (Sheley, et al, 2011), developed for the NRCS:
  1. Protect non-infested rangeland:
  • Only recently have agencies focused on prevention of invasion. The Early Detection and Rapid Control Response techniques have proven effective, “on average, every dollar spent on early intervention prevented $17 in later expenses.” However, these techniques are not implemented widely. Sheley, et al, 2011, found that, “The most successful methods for reducing introductions… are to create a break or diversion.” They concluded that there is little research, and much more research is needed on, “identifying vectors that are major dispersers of invasive plant species.” We lack a strong knowledge base regarding what prevention strategies are most effective. Detecting early infestations, and working to eradicate them while they are small, is important, but little research has been done to determine what unpredictable results may occur. Research shows that “functionally diverse plant assemblages resist invasion better than less-diverse assemblages.” They list several techniques that assist in establishing more diverse ecosystems, including controlled burns, and clipping to simulate grazing.

2. Enhance quantity and quality of commodities; improve forage accessibility, quantity and quality for livestock:
  • Research indicates that increases in forage occur for cattle “where desired species are sufficiently abundant to respond to control procedures.” Long-term studies are needed, to examine the impacts of herbicides on forage. Biological control measures are very limited in use, but do show promise, after multiple years of application. Because sheep prefer broadleaved plants, sheep grazing can be used to increase the grasses preferred by cattle. Grazing has also shown effectiveness in reducing invasive annual grasses, in favor of perennial grasses. The science of reseeding with desired species is not advanced to the point of being consistently successful, “but seeding desirable plants into invasive plant-infested rangeland can increase the quantity and quality of forage for cattle.” Studies using integrated management strategies to repair damaged ecological processes show promise for improving forage for cattle. But some weed management techniques may have only short-term benefits for cattle. Because of the feeding preferences of sheep and goats, “most broadleaf weeds contribute to the forage quantity and quality of sheep and goats,” thus weed management strategies (e.g., herbicides) focused on removal of invasive grasses, do not benefit sheep and goats. Sheley, et al., 2011, recommend grazing cattle, sheep, and goats together, to take advantage of the broadleaf weed grazing abilities of sheep and goats.

3. Control of undesirable vegetation: Is rarely cost-effective, due to the low revenue value of rangeland. The use of herbicides, fire, and other typical practices often result in “rapid reinvasion.” Sheley, et al., 2011, recommend frequent use of grazing, “or infrequent use of more expensive strategies that provide longer-term control, such as restoration.”
  • Prescribed burns have had mixed results, depending on traits of the invading species, and in some cases resulting in increased invasive weed biomass (especially for cheatgrass). Long-term studies on burns have not been conducted.
  • Herbicides are effective “for preventing small… infestations from producing seeds and spreading. They are also effective for controlling weeds during restoration projects…. [But] controlling rangeland invasive plants rarely increases forage production enough to offset the herbicide costs…. Invasive annual grasses often proliferate after herbicides kill associated invasive forbs…. Large-scale herbicide treatments… often kill associated native forbs and shrubs,” which are less likely to recover than are the weeds.
  • Prescribed grazing with “sheep and goats can be economically profitable in well-managed operations or they can serve as additional revenue sources in cattle operations.” But grazing is only effective if carried out prior to invasive plant seed production, and then repeated multiple times during the growing season. Further research is needed on prescribed grazing.
  • Biological control agents have not proven effective for large-scale infestations over the long-term. And “the risks of deleterious off-target effects increase with the number of releases.” However, a few biocontrol agents have been highly effective.
  • Mechanical control methods include tillage and mowing. The effectiveness of these methods has been mixed. The effectiveness of mowing depends on the targeted species, timing and other factors. Mowing or tillage must be reused regularly over time to prevent the recovery of the invader. Further research is needed to determine the effectiveness of seeding with desired species in tilled areas. “Theoretically, when seeded (desirable) species develop self-sustaining populations, these populations should suppress undesirable vegetation indefinitely.”

4. Create a desired plant community: “In many cases, controlling undesired species does not lead to a desired plant community.” Additional methods are needed.
  • Prescribed grazing: Little research has been conducted on the response of native species to grazing, and those studies show mixed results. “To be successful, prescribed grazing will likely need to be carried out indefinitely.”
  • Biological control: There are a number of studies that show that native species do successfully emerge, after reduction of invasive species via biological control agents. Not all studies had this result. The risks are considerable. More long-term research is needed.
​            [Within this website, refer to the section on Biological Control for summaries of the research.]
  • Herbicides: Rangeland herbicides typically kill either grasses or forbs, but not both. “Many native grasses increase following herbicide control of invasive forbs… Similarly, native forbs often increase after herbicides kill invasive grasses.” However, “herbicides are sometimes used to control invasive grasses even though herbicide-sensitive native grasses are present. Likewise, herbicides are used to control invasive forbs growing with native forbs and shrubs.” There are several cases wherein the native species were little affected and were able to recover. But there are other cases where herbicides caused extensive damage to native species. Some herbicides can have serious long-term damaging effects on native species. Herbicides are expensive and often have only short-term effects on weed control.
  • Prescribed fire: “Prescribed fire can boost [some] native species and reduce populations of annual invaders by consuming their seeds.” But effectiveness is based on appropriate timing. Fire can “cause severe damage to native populations, such as big sagebrush… growing with cheatgrass….Weeds generally reinvade very quickly following fire….It is unlikely that managers can burn vegetation regularly enough to maintain native populations, but is possible to integrate fire with other strategies.”
  • Mowing: Studies have shown mixed results. “Native species responses to mowing depend on the relative susceptibility of desired species and invaders to different timings, heights, and frequencies… as well as other factors.” Mowing regimes likely need to be carried out indefinitely.
  • Seeding: Reseeding with desired species shows mixed results, with greater successes occurring in areas with “relatively innocuous weed species.” Seeding is very expensive, and few long-term studies have been conducted. “Nonnative grasses have tended to outperform native grasses in revegetation studies.” [Within this website, refer to the section, Native plants, for a description of the decades-long work of the Texas Department of Transportation, in promoting native plants along roadways].

5. Change underlying causes of weed invasion:
  • Successful weed control is dependent on the cause of the invasion. “Changes to [environmental] conditions are likely to make [native species] less well-adapted, and less able to resist invasion…. These changes can be dramatic, such as soil tillage or improper grazing, or subtle, such as nitrogen deposition or loss…. Among the many underlying causes of invasion, managers have had the most success reversing: … past disturbances, reversed via successful restoration; returning grazing to systems; and enemy release, through biological control…. The presence of perennial [native] species can provide substantial biotic resistance against invasion…. Where desired or native species can be restored, their presence may be sufficient to reduce resource availability and keep invasions from recurring…. Few studies have actually tested whether restoration leads to persistent invasive plant control.” But those studies do support the success of using multiple methods. For example, there has been success when using herbicides and tillage to remove invasive plants, followed by reseeding with native or other desired species.
  • “Where invasion is caused by ongoing disturbance,… or where past changes have led to new stable states, it may also be necessary to change the disturbance regime.” An important example of this is the changes to the fire regime caused by cheatgrass. In sagebrush-steppe ecosystems, “fire suppression is required to allow native species to compete against cheatgrass.” But in tallgrass prairie ecosystems, which are adapted to frequent fires, prescribed burns can provide a long-term solution. Grazing can either “favor or inhibit invasive plants, depending on the grazing history of the site.”
  • Biological control can be an effective method, in some cases, even without altering the environment, depending on the specific invasive species. Reread the warnings above.
  • “Not all causes of invasion can be reversed.” Global changes, such as increases in CO2, or nitrogen deposition or changes in precipitation, all can facilitate invasions. These types of changes to the environment may require the use of non-native [desirable] species in the rehabilitation of ecosystems.
​            [Within this website refer to the summary of the research by DiTomaso, et al., 2017, on Novel Ecosystems].

6. Restore desired vegetative cover to protect soils, control erosion, reduce sediment, improve water quality and quantity, and enhance stream flow:
  • “When desired vegetation has been reestablished on degraded rangeland with low total vegetative cover and a high proportion of bare ground, protection and conservation of soil and water resources generally increase.” However, most restoration programs have not evaluated the impact of restoration on soil or water resources. “Weedy plant communities and desired plant communities may not necessarily differ in their ability to protect and conserve soil and water resources. In some instances, weedy plant communities may be important in rapidly stabilizing heavily disturbed communities on steep slopes.” More research is needed.
  • “Plant cover as well as the proportion and connectivity of bare ground are central factors in determining erosion and sediment yield…. The evidence suggesting that weeds alter soil physical properties is mixed, and appears species-specific…. Soil conservation benefits may be achieved if restoring desired vegetation… increases plant cover and/or decreases connectivity of bare patches and plant interspaces.” More research is needed.
  • “The large negative effect of invasive plant species on water resources and the conservation benefit achieved by restoring desirable species is partially documented on riparian systems…. Several case studies examine weed effects on water resources on uplands and there have been extensive studies on individual plant water use patterns…. Patterns and rates of plant water use are determined by plant size, phenology, rooting depth, and root densities… Weeds that differ significantly from desired vegetation in these traits have the potential to alter the pattern and amount of water available.”
  • Conclusions: “Restoring desired species may not always result in a conservation benefit.” More research is needed. “Basic knowledge about soil stability and hydrological processes allows reasonable prediction of scenarios where restoring desired species will benefit soil and water resources.”

7. Maintain or enhance wildlife habitat including that associated with threatened and endangered species:
  • “Invasive species often change ecosystem structure and function, directly impacting wildlife habitat…. Invasive species removal has been shown to benefit wildlife in a number of systems. Relationships between invasive plant species and wildlife, however, are often more complicated, involving both positive and negative effects.” Example: salt cedar provides “suitable habitat for the endangered southwestern willow flycatcher… and other avian species that nest in midcanopy vegetation, but poor habitat for many other avian species.” More research is needed, but knowledge of species-specific habitat requirements can help predict in which cases removal of invasive plant species will benefit wildlife. Sheley, et al., 2011, describe various studies that have shown increases in wildlife when invasive species have been removed, and several cases in which removal methods have had a negative impact on wildlife.

8. Protect life and property from wildfire hazards:
  • Most arid western ecosystems are well adapted to fire. However, each ecosystem is adapted to a specific fire regime. Some ecosystems, e.g., riparian corridors, sagebrush scrub, and deserts, have “longer fire-return intervals because of sparse and discontinuous vegetation…. Invasion by annual grasses, particularly cheatgrass, red brome…, and medusahead, have dramatically shortened the intervals between fires.” More frequent fires can cause permanent damage to native species. But fire suppression can “create undesirable conditions for both forest sustainability and human fire hazard.” Western juniper, a native species, has expanded its range dramatically in the northwest as a result of fire suppression. “Each year millions of dollars are spent on emergency post-fire rehabilitation treatments.”
  • Following fires in the 1990s in southern California, attempts to mitigate soil erosion on hill slopes, using non-native annual grasses and forbs, has backfired. The revegetation attempts have been largely unsuccessful and have exacerbated invasive plant species encroachment. Soil stabilization would be more successful if burn areas are replanted with deep-rooted perennial shrubs. More research is needed.

9. Minimize negative impacts of pest control on soil, water, air, plant, and animal resources:
  • Research on commonly used methods of invasive plant species control suggests that herbicides, tillage, and grazing can create increased disturbances, that increase invasions. Between 1976 and 2008, few studies had been conducted on herbicide impacts on abiotic resources and native species. “The effect of herbicide on desirable vegetation remains difficult to predict.”
  • Newer rangeland management programs are using “tools that minimize disturbance such as no-till drills and moderate grazing.”
  • Biological control: “When operating under current protocols there are relatively few documented direct effects… on desirable vegetation… There is, however, mounting evidence suggesting that poor monitoring efforts, difficulty in predicting biocontrol effects, and the largely unrecognized indirect effects biocontrols can have on ecosystems contributes to an underestimation of the detrimental effects… on desirable vegetation… For example, the bulk of biocontrol monitoring focuses on release sites with little attention paid to offsite biocontrol effects even though there is strong evidence demonstrating landscape-scale variation in biocontrol effects on desirable vegetation… In addition, it is estimated that less than half of the biological control efforts… in the United States demonstrated any evidence of control…. [In addition] recent literature [shows] complex indirect effects of biocontrol on desirable vegetation. For example, following the collapse of the target population, intense competition among biocontrol agents can cause a transient increase in host plant range, which results in the biocontrol agents attacking desirable species… When biocontrol agents only moderately damage invasion plants they may increase invasive plant…compensatory growth… Current procedures do not adequately prevent biocontrol efforts from having significant effects on desirable vegetation.” Other research indicates that biocontrol insects can have negative direct or indirect impacts on native insects and other animals, such as mice, within the food chain.
  • Grazing: “In general, when grazing is limited to periods when weedy species are most susceptible to defoliation and desirable plants are largely dormant, the impact of grazing on desirable vegetation can be minimized and benefit of grazing for weed control maximized…. If weedy and desirable vegetation have comparable forage quality, grazing animals largely will consume plants in proportion to their abundance.” Thus, grazing is more affective in areas with relatively high densities of invasive species. If weeds have low forage value, grazing may have a greater negative impact on desirable vegetation. But it is difficult to predict the impact of grazing on desirable species. More research, with close monitoring, is needed.

USDA Forest Service priorities, 2010
 
In A dynamic invasive species research vision: Opportunities and priorities 2009-2029 (Dix & Britton, 2010), teams of researchers conducted reviews of the research on invasive species, in order to facilitate the development of a twenty-year research agenda for the US Forest Service. The review included research on the following categories of invasive species: insects, plants, terrestrial animals, aquatic organisms, and invasive soil organisms. This valuable research review was coalesced by Forest Service research teams into 12 visionary papers developed to “identify future invasive species research issues and priorities and provide the Forest Service and its partners with a framework for programming and budgeting.”
 
In that document, Britton, at al., 2010, p. 4, state that, “Forest Service Research and Development (R&D) has developed a more holistic view of our invasive species research program as we implement the National Strategy and Implementation Plan for Invasive Species [now called the National Strategic Framework for Invasive Species Management]. This agencywide strategy, which tiers from the National Invasive Species Council’s Management Plan, organizes our invasive species work in four broad activity areas: (1) prediction and prevention, (2) early detection and rapid response (EDRR), (3) control and management, and (4) rehabilitation and restoration.”
 
Also in that document, Sieg, et al., 2010, p. 38-39, state, “Land managers lack many basic tools for reducing the effects of invasive species on severely infested lands….Mitigation of invasive effects and increasing resistance to future invasions are accomplished through restoration and rehabilitation activities. We need research to develop vegetation management protocols to restore ecosystem processes and reduce the effects of invasives, also recognizing those situations where restoration is neither feasible nor desirable... There is a need to develop ecologically sound restoration methods that consider the contributions of genetics, population and community structure, and ecosystem processes to invasion resistance. Disturbance, high-propagule pressures, legacy effects such as seed banks, and changes in disturbance regimes and nutrient supply may impede long-term restoration success.”
​
References:
  • Britton, K.O., Buford, M., Burnett, K., Dix, M.E., Frankel, S.J., Keena, M., Kim, M,. Klopfenstein, N.B., Ostry, M.E., & Sieg, C.H. (May, 2010). Invasive species overarching priorities to 2029. In M.E. Dix & K. Britton (Eds.), A dynamic invasive species research vision: Opportunities and priorities 2009-2029. Washington, D.C.: USDA Forest Service.
  • DiTomaso, J.M., Monaco, T.A., James, J.J., Firn, J. (2017). Invasive plant species and novel rangeland systems. In D. Briske (Ed.), Rangeland Systems: Processes, Management & Challenges: 429-465. Springer Series on Environmental Management. Springer, Cham.
  • Dix, M.E., & Britton, K. (Eds.). (May, 2010). A dynamic invasive species research vision: Opportunities and priorities 2009-2029. Washington, D.C.: USDA Forest Service.
  • Sheley, R.L., James, J.J., Rinella, M. J., Blumenthal, D., & DiTomaso, J.M. (2011). Invasive plant management on anticipated conservation benefits: A scientific assessment. In D.D. Briske (Ed.) Conservation benefits of rangeland practices: Assessment, recommendation, and knowledge gaps. (pp. 293-336). USDA Natural Resources Conservation Service.
  • Sieg, C.H., Denslow, J.S., Huebner, C.D., & Miller, J.H. (May, 2010). The role of the Forest Service in nonnative invasive plant research. In M.E. Dix & K. Britton (Eds.), A dynamic invasive species research vision: Opportunities and priorities 2009-2029. Washington, D.C.: USDA Forest Service.
  • USDA Forest Service. (2013). National Strategic Framework for Invasive Species Management. USDA Forest Service.

​Links to Rangeland Restoration:​
  • Novel Ecosystems
  • ​Prairie Restoration
  • Sagebrush Steppe Restoration
  • Revegetation with Native Plants
  • Dogs as detectors of noxious weeds

Links to other Innovative Solutions:
Agricultural best practices
grazing solutions
Nudges
Copyright: Dr. Delena Norris-Tull, July 2020. Management of Invasive Plants in the Western USA.

These webpages are always under construction. I welcome corrections and additions to any page.
​Send me an email, and I can send you the original Word format version of any page you wish to correct.
contact Dr. Norris-Tull
Bibliography
who am i?
My work
my inspirations
my adventures
  • Defining the Problem
    • What is a Weed? >
      • Federal Definitions of Noxious Weeds
    • Costs of invasive plants
    • Human Factor
    • Challenges of Invasive Plants
    • Wildfires in the Western USA >
      • Forest Fires: Structure
      • Bark Beetles & Forest Ecosystems
      • Rangeland Fires
    • Climate Change Impacts on Plants >
      • Climate Change: CO2, NO, UV, Ozone Impacts on Plants
      • Climate Change Impacts on Crops
      • Climate Change Impacts on C4 Plants
      • Climate Change Impacts on Rangeland
    • What are we doing?
  • Focus of this Project
    • Why Western States? >
      • Audience for these reports
    • History: Are we doomed to repeat it? >
      • Dust Bowl Re-visited >
        • China: Past & Present
        • UN Biodiversity Report
    • Policy vs. Practice
    • Ecosystems & Economics >
      • Reductionist Approach to science
      • Ecology & Feminism
      • Systems View of Life
      • Ecosystems Health
      • Economic Growth
      • Impact of the Petrochemical Industry
      • Interrelation of Economics & Ecology
    • Federal Agencies >
      • Federal Agencies and Invasive Species
      • History of Coordination with States
      • Challenges of Coordination between Federal Agencies
      • Collaboration or Confusion
    • Organizations to assist landowners
    • Federal Legislation on Invasive Species >
      • 1930s Federal Laws on Invasive Species
      • Federal Seed Act 1939
      • 1940s-1960s Federal Laws on Invasive Species
      • 1970s Federal Laws on Invasive Species
      • 1980s Federal Laws on Invasive Species
      • 1990s Federal Laws on Invasive Species
      • 2000-2010 Federal Laws on Invasive Species
      • 2011-2022 Federal Laws on Invasive Species
      • Federal Bills on Invasive Species not passed
      • Executive Orders on Invasive Species
      • Federal Excise Taxes
    • State Laws and Lists of Noxious Weeds
    • My Inspirations
  • Why we need plants
    • Native Plants
    • Plant Resources
  • Invasive Success Hypotheses
    • Unified Framework
    • Role of Diversity >
      • How Ecosystems Maintain Diversity
      • Fluctuation Dependent Mechanisms
      • Competition-based coexistence mechanisms
      • Niche Differences
      • Species Richness
    • Enemy Release Hypothesis
    • Constitutive Defense Mechanisms
    • Evolution of Increased Competitive Ability
    • Role of Microbes
    • Indirect Defense Mechanisms
    • Novel weapons hypothesis
    • Evolutionary Shifts
    • Resource Allocation
    • Evolutionary Dynamics >
      • Pre-introduction evolutionary history
      • Sampling Effect
      • Founder Effect
      • Admixture, hybridization and polyploidization
      • Rapid Evolution
      • Epigenetics
      • Second Genomes
    • Role of Hybridization
    • Role of Native Plant Neighbors
    • Species Performance
    • Role of Herbivory
    • Evolutionary Reduced Competitive Ability
    • Summary Thoughts on Research
  • Historical Record
    • Regional Conferences
    • Timeline
  • Innovative Solutions
    • Agricultural Best Practices >
      • Ecologically based Successional Management
      • Perennial Crops, Intercropping, beneficial insects
      • Soil Solarization
      • Natural Farming
      • Permaculture
      • Organic Farming
      • Embedding Natural Habitats
      • Conservation Tillage
      • Crop Rotation
      • Water Use Practices
      • Tree Planting: Pros & Cons
    • Grazing Solutions >
      • Sheep and Goat Grazing
      • Cattle & Sheep Grazing
      • Cattle and Bison Grazing
      • Grazing and Revegetation
    • Rangeland Restoration >
      • Federal Goals for Rangelands
      • Novel Ecosystems
      • Prairie Restoration >
        • Prairie Restoration Workshop
        • Weed Prevention Areas
        • California grassland restoration
        • Selah: Bamberger Ranch Preserve
      • Sagebrush Steppe Restoration >
        • Low Nitrogen in Sagebrush Steppe
      • Revegetation with Native Plants
      • Dogs as detectors of noxious weeds
    • Nudges
  • Biological Control
    • Insects as Biocontrol >
      • Impacts of Biocontrol Agents on Non-Target Species
      • Indirect Impact of Biocontrol on Native Species
    • Challenges of Using Biocontrols >
      • DNA studies on Biocontrol Insects
      • Biocontrol takes time
    • Prioritization process for Biocontrol Programs
    • Evolutionary changes impact Biocontrol
    • Vertebrates as Biocontrol Agents
  • Herbicides: History and Impacts
    • Effectiveness of Herbicides in Agricultural Lands
    • Effectiveness of Herbicides in Rangelands
    • History of Use of Herbicides and Pesticides Prior to and During WWII
    • Herbicide use during and post-World War II >
      • 2,4-D Herbicide Use
      • 2,4-D and 2,4,5-T, post-World War II
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