Invasive Species Management Notes

Introduction to Invasive Species Management

  • Invasive Species Defined: Introduced species that spread and become harmful to ecosystems.

  • Importance: Addressing invasive species is critical for biodiversity, ecosystem health, and human economic interests.

Invasion Ecology

  • Discipline: Studies the establishment, dispersal, and ecological impacts of non-native species introduced by human activities.

  • Key Considerations:

    • Invasion characteristics.

    • Dispersal patterns.

    • Consequences of invasion.

Invasion Curve

  • Phases of Invasion:

    • Prevention: Preventing establishment.

    • Eradication: Achieving the complete removal of a localized population.

    • Containment: Limiting the spread of established populations.

    • Management: Long-term strategies aimed at suppression and protection.

Definitions of Key Terms

  • Source-Sink Dynamics:

    • Source Populations: Self-sustaining populations that supply individuals to sink populations.

    • Sink Populations: Populations reliant on immigration from sources; vulnerable if the source is halted.

  • Established Species: A reproducing and self-sustaining population beyond localized areas.

  • Feral Species: Cultured species that have escaped and established in the wild.

  • Cryptogenic Species: Species of uncertain status (possibly nonindigenous).

  • Native species – A species occurring within its “natural” range. Note that species ranges change over time.

  • Colonization- implies successful reproduction in the new area, not simply the presence a species there

  • Reproducing – individuals may be producing offspring but are not persistent or self-sustaining

  • Formerly reproducing – reproducing population but eradicated by human action, natural events, or demographic processes

  • Reported – Documented but without clear evidence of reproduction (often found as single individuals

Non-Native Species Overview

  • Over 37,000 non-native species globally, with 3,500 invasive species recognized.

  • Species Distribution: New introductions average at 200 species/year with a breakdown as follows:

    • Plants: 6%

    • Invertebrates: 22%

    • Vertebrates: 14%

    • Microbes: 11%

Examples of Invasive Species

  • Most Damaging:

    • Giant Cane (Arundo donax): Alters water balance & highly flammable.

    • Shoebutton Ardisia (Ardisia elliptica): Inhibits growth of native plants.

    • Asian Long-Horned Beetle (Anoplophora glabripennis): Can cause tree mortality.

  • Costly Species:

    • Aedes Mosquitos: ~$149 billion impact due to disease transmission.

    • Rats: ~$67 billion impact through competition and crop damage.

Pathways of Introduction

  • Natural Dispersal: Through wind, water, and animal movements.

  • Human-Mediated Introduction: Trade, travel, and transport, including:

    • Accidental Introductions: Unintentional spread via goods and vehicles.

    • Intentional Introductions: For agriculture, sport, or ornamental purposes.

Characteristics of Successful Invasive Species

  • High Reproductive Rates: Typically r-selected species.

  • Generalists: Capability to live in diverse conditions.

  • Wide Environmental Tolerance: Ability to thrive across various habitats.

  • High Genetic Variability: Ensures adaptability.

Effects of Invasive Species

  • Negative Economic Impact: U.S. loses about $21 billion/year due to invasive species.

  • Ecological Consequences:

    • Biodiversity loss: Non-native fish contribute to extinctions (>68%).

    • Hybridization risks causing genetic dilution in native populations.

    • Trophic alterations leading to resource competition.

Management Strategies

  • Preventative Measures: Database monitoring (e.g., EDDMapS helps track species).

  • Control Measures:

    • Chemical: Use of herbicides and pesticides.

    • Mechanical: Physical removal of invasive species.

    • Biological Control: Natural predators or diseases to manage populations.

Regulatory Framework

  • Federal Laws:

    • Lacey Act: Regulates transport and sale of wildlife.

    • Aquatic Nuisance Prevention Act: Focuses on aquatic invasives management.

    • Executive Orders: Establish policies for preventing and controlling invasive species.

Summary

  • Understanding invasive species is vital for protecting ecosystem health and biodiversity.

  • Key data limitations necessitate ongoing research efforts to better document and predict the impacts of non-native species.