LETHBRIDGE, Alta. – The alien invasion is here and most people don’t even know it
happened.
The aliens are not little green men, but tenacious green plants that are taking over millions of acres of land in North America. These plants may appear as pretty flowering plants or hardwood trees that defy destruction.
“We are being invaded by alien species and no more than five percent of the population knows what is happening,” said Don Schmirtz of Florida’s department of environmental protection. His job is to combat invasive weeds in his state. He is armed with little money or staff.
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The prognosis isn’t good.
“A battle is being lost against biological invaders,” he said at the North American Weed Management Association meeting in Lethbridge. The seven-year-old association looks at problem weeds, many of which were imported to the continent by people.
These plants are not welcome, because they outgrow native species and suck away water and space. Some are predators that carry diseases that local plants can’t fight.
Florida was among the first states to experience the invasion of foreign species.
Today there are problems ranging from Rhesus monkeys left over from Tarzan movie shoots in the 1930s to the melaleuca tree that is taking over the beaches.
Florida has 900 plant invaders and 1,100 new insect varieties as well as mammals, birds and reptiles like tree frogs and iguanas.
Spanish explorers introduced the water
hyacinth that permeates Florida waters. The Giant African Salvinia has infested areas in Florida and is moving into Texas and Louisiana. It has consequences for water chemistry because it reduces oxygen levels in the water.
Melaleuca trees imported from Australia to drain swamps have overtaken beaches and have pushed out pine forests. One tree can yield 17,000 seedlings.
Melaleuca changes the soil topography and wildlife moves out of the forest because there is no cover. Litter on the forest floor does not break down because the Australian bacteria are not there to get rid of it.
Other troublesome plants were imported by exotic plant nurseries. Ninety percent of the alien plants were introduced as ornamentals.
Other species blow in after hurricanes. The new plants change water alkalinity and kill phytoplankton.
Agriculture feels the effects of these foreign plants and animals.
Tropical soda apples invaded pastures in 1981 and have spread rapidly. Cattle find the plants unpalatable but will eat the fruit and spread it further when the seeds pass through manure.
It has spread over one million acres in the southeastern United States. Florida has managed alien species poorly, but has made some progress since the mid 1990s, Schmirtz said.
His department and related agencies have won some battles with water hyacinth, while hydrilla has been reduced by 35,000 acres.
About 50 million melaleuca trees have been removed since 1990 at a cost of $15.5 million (U.S.) There are a number of groups trying to combat this problem, but there isn’t enough money or staff to control it effectively.
United States president Bill Clinton signed an executive order in February to establish an invasive species council.
It encourages various agencies to work together, but does not say how.
Schmirtz said people are the primary problem, because there are differing opinions about control methods. There is also a lack of money and co-ordinated research.
Schmirtz wants a North American agency for weed control similar to the centre for disease control. At the moment, local groups are responsible for controlling invasive species.
A continental agency could list known harmful invaders, outline losses and compile a list of management practices.
The centre could work with other countries to exchange surveillance information and implement electronic data reporting.
Funds for such a body could come from agricultural, forestry and water agencies.
The centre would have five main goals:
- Detect and monitor invasions of foreign species.
- Invest in university research.
- Provide public education.
- Allow information exchange among agencies.
- Create regional centres of expertise.
