Invasive Species Choke Natives

First published June 2, 2018

California Floristic Province

The California Floristic Province is considered a world biodiversity hotspot. It contains a large number of ecosystems that include alpine forest, mixed evergreen forest, riparian forest, sagebrush steppe, coastal sage scrub, redwood forests and more.

Currently, only 25% of the original vegetation remains unharmed.

Highly populated and a producer of agriculture products for 50% of the country, California is also considered ‘one of the four most ecologically degraded expanses in the US.’

Additional Threats to Biodiversity

  • air pollution
  • mining & oil extraction
  • livestock grazing & wildfires
  • invasive species

Fragmentation [human building] has the capacity to generate persistent, deleterious, and often unpredicted outcomes, including surprising surges in abundance of some species and the pattern that long temporal scales are required to discern many strong system responses. National Center for Biotechnology Information

Characteristics of Invasive Species

  • successful invasion elsewhere
  • ability to live near humans
  • food source variety
  • survives in a wide range of environments
  • alters growth to suit changing conditions
  • grows and reproduces quickly
  • fast spreading
  • difficult to eradicate

Invasive species and biodiversity preservation is a topic much larger than one blog post can cover! Below is a brief list of plants commonly found in Nevada County.

The ‘Resources’ section at the bottom of the page contains links for extensive exploration.

Blackberry / Rubus Fruticosus

Blackberry

Origin

Spain

Behavior

Creates an impenetrable thicket (bramble).
Grows in areas where soil has been disturbed such as land grading, agriculture tillage, timber logging, housing construction, wildland firebreaks, animal grazing, and road building.
Provides shelter for rats and food for deer.
Damages livestock.

University of California Agriculture and Natural Resources – Management and Control of Blackberries

Hydrilla / Hydrilla Verticillata – Water Thyme

Hydrilla

 

Origin

Sri Lanka / Korea. Imported as an aquarium plant in the 1950s

Behavior

Aggressively invades new aquatic environments.
Displaces native vegetation.
Forms large dense mats.
Impedes water flow.
Cloggs pumps.
Reduces water clarity.
Alters the ecosystem.
Blocks sunlight.
Decreases oxygen water levels, killing fish.
Reduces recreational water use.
Fragments easily carried to new waterways.
Impedes waterfowl feeding.
Impedes fish spawning.
Devalues waterfront property values.
Impedes water treatment and power generation.

UC Davis – Hydrillia – Weed Control in Natural Areas in the Western United States [PDF]

Yellow Starthistle / Centaurea Solstitialis

Yellow Starthistle

Origin

Chilean-harvested alfalfa imported during the California Gold Rush.

Behavior

Grows in areas where soil has been disturbed such as land grading, agriculture tillage, timber logging, housing construction, wildland firebreaks, animal grazing, and road building.
One plant can produce nearly 75,000 seeds.
Alters water cycles.
Poisons livestock.
Overtakes native plants.

California Invasive Plant Council – Yellow Starthistle Management Guide [PDF]

California Invasive Plant Council – Yellow Starthistle Management Guide [PDF]

Scotch Broom / Cytisus Scoparius

Scotch Broom

Origin

Imported from Europe in the mid-1800s as a land stabilizer and garden accent.

Behavior

Aggressively displaces native plant populations.
Highly flammable.
Fire hazard.
Seeds can remain active for over 80 years.
A mature shrub can produce up to 15,000 seeds.
Seeds can be transported over long distances by animals, water, vehicles, and people.
Grows in a variety of soil conditions.
As a legume, it changes soil chemistry.
After removal, native plants won’t repopulate.

Fire Safe Council of Nevada County  – Management and Control of Scotch Broom

Mussels & Moths

Not pervasive, yet, in California, these animals have caused large-scale agriculture, water and forest management, and recreational problems in other states.

Carefully inspecting possessions after traveling from infested areas, and cooperation with Agriculture Inspection Station agents are ways to help prevent a species invasion.

Quagga / Dreissena Rostriformis Bugensis & Zebra Mussels / Dreissena Polymorpha

Origin

Caspian and the Black Sea and Dnieper River, Ukraine. Brought into the Great Lakes in the 1990s through ship ballast water.

Behavior

Disrupts ecological water balance.
Reduces recreational value, shells overrun sandy beaches.
Impedes water flow.
Encrusts pipes and other structures.
One muscle can produce 5,000,000 eggs during its 5-year lifespan.
Estimated Five billion community costs since first discovery.

Oregon Sea Grant – Zebra and Quagga Mussel Prevention and Control [PDF pg. 7]

European Gypsy Moth / Lymantria Dispar

Origin

Europe and Asia. Escaped from breeding experiments in Massachusetts in the 1960s.

Behavior

Voraciously eats tree leaves and shrubs.
A single moth can consume a square foot of leaves per day.
Leaves caterpillars eat – cedar, pine, fir, spruce, aspen, oaks, birch, alder, manzanita, and western hemlock.

US Forest Service – Gypsy Moth Prevention & Control

There is an urgent need for conservation and restoration measures to improve landscape connectivity, which will reduce extinction rates and help maintain ecosystem services. National Center for Biotechnology Information

If you liked this post, you may also like Native Plants for Healing the Land

click on image to see more invasive species Life on the Creek art

 

Resources:

Alameda County Department of Agriculture – Pest Detection (photos)
American Bullfrog – California Department of Fish and Wildlife
Blackberry
 – NCRCD
Blackberry, Wild – the University of California Agriculture and Natural Resources
California Department of Fish and Wildlife – California Invaders
California Department of Fish and Wildlife – Why can’t I have a hedgehog, sugar glider, ferret, or other restricted, non-native species as a pet in California?
California Department of Food and Agriculture – Gypsy Moth
California Invasive Plant Council
California Invasive Plants A-Z
CBS Video – Invasive Species Spreading Across America
Common Pokeweed – California Invasive Plant Council
Fire Safe Council of Nevada County – Scotch Broom Challenge
French Broom – California Invasive Plant Council
Hydrilla – NCRCD
Invasive Species Council of California
List of California Native Plants – Wikipedia
National Center for Biotechnology Information, U.S. National Library of Medicine – Habitat fragmentation and its lasting impact on Earth’s ecosystems (2015)
Nevada County Resource Conservation District
Portuguese Broom –  California Invasive Plant Council
Quagga & Zebra Muscle Infestation & Prevention Program – NCRCD
Scotch Broom – California Invasive Plant Council
Spanish Broom – California Invasive Plant Council
UC Division of Agriculture and Natural Resources – Harmful Shrubs get a Foothold in California Forests
US Department of the Interior Bureau of Reclamation – Quagga and Zebra Muscles
Weed Threats – My Nevada County
Invasive Species – Wikipedia
Yellow Star Thistle – California Invasive Plant Council

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