A plant brought to California nearly 200 years ago has become a serious invasive weed in parts of the state.
asserted
plant → bring → state
Giant reed, also known as arundo, was first planted in California in the 1820s to provide roofing material and help control erosion in the Los Angeles Basin.
asserted
reed → know → Basin
According to Center for invasive species research, the plant, scientifically known as Arundo donax, is native to eastern Asia.
uncertain
plant → accord → Asia
It was widely planted in different parts of the world because it could be used for several purposes, including walking sticks, fishing poles and musical instruments.
uncertain
it → plant → sticks
It is also being investigated as a possible biofuel source.
asserted
It → investigate → source
Over time, however, giant reed became an
invasive weed in several regions where it was introduced.
asserted
it → become → regions
The University of California, Riverside’s Center for Invasive Species Research lists California among the areas where the plant has become a problem, along with parts of Texas, Hawaii, Nevada, Utah, Missouri, Virginia, New Mexico and Florida.
asserted
plant → list → Texas
One reason giant reed can spread so effectively is its rapid growth.
asserted
reed → spread → ?
The plant can grow about 4 inches a day and reach a mature height of 25 feet in about 12 months.
asserted
plant → grow → months
It can also tolerate a range of environmental conditions, allowing it to grow in damp riparian areas and in moderately saline soils.
asserted
it → tolerate → soils
Dense growth pushes out native plants
Giant reed can form dense stands that leave little room for native vegetation.
asserted
that → push → vegetation
Native plants are typically displaced when arundo becomes established.
asserted
arundo → displace → ?
Animals associated with those native plants may also be unable to use the dense stands of giant reed, leading to declines in their populations.
uncertain
Animals → associate → populations
The problem is particularly serious in California, where arundo can choke out native willows.
asserted
arundo → choke → willows
Its presence also creates a fire risk because the plant can provide large amounts of fuel in riparian areas, where fires are typically uncommon.
asserted
fires → create → areas
The plant is also well adapted to fire.
asserted
plant → adapt → fire
This creates another problem because fires can help promote arundo invasions in sensitive habitats.
asserted
fires → create → habitats
In the Santa Ana River Basin in Southern California, the fire fuel load in riparian areas has almost tripled because of arundo infestations.
asserted
load → triple → infestations
The plant can create problems during floods as well.
asserted
plant → create → floods
Large amounts of arundo can be dislodged and carried by floodwater.
asserted
amounts → dislodge → floodwater
These pieces can form large rafts, and tons of the plant can build up around bridge supports.
asserted
tons → form → supports
Such accumulations can cause bridges to collapse.
asserted
bridges → cause → ?
Giant reed also uses large amounts of water
The invasive plant's impact is not limited to native vegetation and fire risk.
asserted
impact → use → vegetation
Its water use has also been studied in the Santa Ana River.
asserted
use → study → River
Research cited by the Center for Invasive Species Research estimated that arundo transpires 56,200 acre-feet of water each year on the Santa Ana River.
asserted
arundo → cite → River
Native vegetation was estimated to consume 18,700 acre-feet.
asserted
vegetation → estimate → feet
The difference was estimated at 37,500 acre-feet of water.
asserted
difference → estimate → water
The study said that if arundo were not drawing this water from the Santa Ana River Basin, there would be enough water to serve a population of about 190,000 people.
asserted
arundo → say → people
The same study estimated that purchasing that amount of untreated water from the Metropolitan Water Association would have cost approximately $12 million in 1993 dollars.
asserted
purchasing → estimate → dollars
The economic study was conducted in 1993.
asserted
study → conduct → 1993
Scientists studying ways to control it
Researchers at the University of California are studying the invasion ecology of arundo and different ways to control it.
asserted
Researchers → study → it
These include the use of herbicides and mechanical removal from areas where the plant has spread.
asserted
plant → include → areas
Another approach being developed by USDA-ARS researchers in Texas is biological control.
asserted
approach → develop → Texas
The strategy involves using natural enemies that feed on arundo and could reduce its growth.
uncertain
that → involve → growth
In California and other parts of the US, there are no organisms that cause substantial feeding damage or mortality to arundo.
asserted
that → be → arundo
The lack of natural herbivores has partly allowed the plant to flourish in areas it has invaded.
asserted
it → allow → areas
Researchers searching for arundo's natural enemies in its native range have identified several insects that could potentially reduce the plant's vigour by feeding on it.
uncertain
that → search → it
These include the Arundo wasp, Tetramesa romana; the Arundo scale, Rhizaspidiotus donacis; and the Arundo fly, Cryptonevra species.
asserted
These → include → wasp
Safety evaluations have found that these insects are highly host-specific and pose no substantial threat to other plants.
asserted
insects → find → plants
Efforts are now under way to mass rear these natural enemies and establish them in areas with severe arundo infestations.
asserted
Efforts → rear → infestations
…and 4 more, not listed.
The Aporia
