Frequently Asked Questions (FAQ's)
- What's the big deal? Why should I be concerned?
- What is the difference between non-native and invasive?
What's the big deal?
Why should I be concerned?
- What is the
difference between non-native and invasive?
By definition, “an invasive species is a non-native species whose introduction causes or is likely to cause economic or environmental harm, or harm to human health.”
Many plants and animals have been introduced to Arizona for a host of reasons and by a number of different pathways over the last 150 years or so. Some non-native species were introduced intentionally to serve a purpose, others hitchhiked in or were accidentally introduced, and still others may have migrated into Arizona after having been introduced outside our borders. Many introduced plants and animals serve beneficial purposes or bring value to the citizens of our state. But some introduced plants and animals can cause problems or harm. Those are the non-native species that we are concerned about as invasive.
One of the challenges with definitions is that, unless they are yes-or-no kinds of definitions, people interpret the definition broadly or narrowly. Our definition of Invasive Species is one that is subject to a variety of interpretations. Our focus in on the kinds of plants and animals that we can agree have few or no redeeming qualities and pose existing or potential future risks to Arizona’s economy, environment, or to the health of our citizens.
Many invasive species might be considered “weedy” species. Those “weedy” invasive plants and animals often have broad environmental tolerances, and when they make their way to a new environment they have few natural limits or controls on their population. So many invasive species can grow fast, reproduce frequently and generate lots of offspring, and can expand the range that they cover very quickly. Invasive species can crowd out native and beneficial non-native species because they are better competitors; can disproportionately preyed upon natives and beneficial non-natives; or can alter the environment in a way that makes it inhospitable to native and beneficial non-native species. Yellow starthistle, and invasive plant, grows so densely that it crowds out native grasses and forbs on rangelands and provides little or no nutritive value to animals – in fact it is toxic to horses. Bullfrogs, intentionally and accidentally introduced, are significant predators upon native aquatic animals like leopard frogs, decimating populations. Buffelgrass, rapidly invading parts of southern Arizona, out-competes native plants for soil nutrients and radically changes the wildfire-carrying capacity of the landscape threatening valued Sonoran desert landscapes and human residences. And quagga mussels, a hitchhiker that recently arrived in Arizona, is so prolific in lakes where it occurs now that significant new costs will be incurred by operators of dams, irrigation facilities, hydropower facilities, and lake amenities – and we still do not know how much they will affect lake ecosystems.
WEEDS AND GRASSES
A. The increase in desert wildlands fires has been fueled by the growing presence of non-native grasses, including buffelgrass, red brome and fountain grass. Red brome has been recognized as the principal fuel in the Cave Creek Complex Fire.
B. The presence of these weeds with the addition of Lehmann lovegrass, cheatgrass and malta starthistle have been shown to replace existing native plants and grasses resulting in a significant decrease in species richness and the alteration of ecosystem processes.
A. The quagga mussel can survive and reproduce in a wide range of habitats producing 40,000 eggs per breeding cycle with multiple cycles every year. The quagga mussel consumes significant amounts of phytoplankton disrupting the ecological balance of entire bodies of water.
B. In addition the quagga mussel, already found in Lakes, Mead, Havasu, Mohave and Lake Pleasant as well as the CAP have been found to accelerate corrosion on bridges, docks and navigational equipment requiring increased maintenance time and costs for cleaning. This mussel can clog supply lines and pumps disrupting water flow and creating damage to entire water supply systems.
A. Crayfish are not native to Arizona and have no natural predators. Their presence in the state is widespread and represents an important example of how large an area an invasion of one of these Invasive Species can overtake.
B. The crayfish can move considerable distances infesting any body of water they enter. They will eat almost anything including insects, snails and other invertebrates. Once they have eliminated these food sources they move on to larger prey, including tadpoles, fish, frogs and even young turtles. This voracious appetite completely alters the aquatic environment eventually results in no food source so they eat each other.
A. The Asian tiger mosquito has invaded 25 states in The United States including Arizona. This aggressive biter is a competent vector for diseases such as dengue, West Nile virus, St. Louis encephalitis and others.