How can introduced plants be harmful

In addition, higher average temperatures and changes in rain and snow patterns caused by climate change will enable some invasive plant species—such as garlic mustard, kudzu, and purple loosestrife—to move into new areas. Insect pest infestations will be more severe as pests such as mountain pine beetle are able to take advantage of drought-weakened plants. Invasive species cause harm to wildlife in many ways. When a new and aggressive species is introduced into an ecosystem, it may not have any natural predators or controls.

It can breed and spread quickly, taking over an area. Native wildlife may not have evolved defenses against the invader, or they may not be able to compete with a species that has no predators.

The direct threats of invasive species include preying on native species, outcompeting native species for food or other resources, causing or carrying disease, and preventing native species from reproducing or killing a native species' young. There are indirect threats of invasive species as well. Invasive species can change the food web in an ecosystem by destroying or replacing native food sources. The invasive species may provide little to no food value for wildlife.

Invasive species can also alter the abundance or diversity of species that are important habitat for native wildlife. Aggressive plant species like kudzu can quickly replace a diverse ecosystem with a monoculture of just kudzu. Additionally, some invasive species are capable of changing the conditions in an ecosystem, such as changing soil chemistry or the intensity of wildfires.

Invasive carp are fast-growing, aggressive, and adaptable fish that are outcompeting native fish species for food and habitat in much of the mid-section of the United States. The huge, hard-headed silver carp also pose a threat to boaters, as the fish can leap out of the water when startled by boat engines, often colliding with people and causing injuries. Voracious filter feeders, invasive carp consume up to 20 percent of their body weight each day in plankton and can grow to more than pounds.

Invasive carp were imported to the United States in the s to filter pond water in fish farms in Arkansas and quickly spread across the country. Flooding allowed them to escape and establish reproducing populations in the wild by the early s. Invasive carp are swiftly spreading northward up the Illinois River, and are now on the verge of invading the Great Lakes.

Once established in an ecosystem they are virtually impossible to eradicate. Adult invasive carp have no natural predators in North America and females lay approximately half a million eggs each time they spawn.

Parts of the Great Lakes, including nutrient-rich bays, tributaries, and other near-shore areas, would offer invasive carp an abundant supply of their preferred food, plankton. Plankton is also favored by most young and many adult native fishes and the voracious carp would likely strip the food web of this fundamental resource.

The U. Geological Survey has identified 22 rivers in the U. The brown marmorated stink bug, Halyomorpha halys, is native to China, Japan, and surrounding countries. They were first discovered in the United States in Pennsylvania during the late s, but no one knows for certain how they were introduced to North America.

Brown marmorated stink bug BMSB populations are exploding in the absence of their natural predators, and they are quickly becoming a nuisance to people in their homes and to the agriculture industry. The bugs begin to come indoors, searching for warm, protected areas when outside temperatures turn cooler in the fall. BMSBs feed on host plants by piercing the skin and consuming the juices within; the signs of stink bug feeding appear as "necrotic" or dead spots on the surface.

A wide variety of plants are known food sources for BMSBs, including ornamental trees and shrubs; fruit crops like peaches, apples, grapes, and pears; vegetable crops like green beans and asparagus; and soybeans and corn. Zebra mussels and quagga mussels are virtually identical, both physically and behaviorally. Originally from Eastern Europe, these tiny trespassers were picked up in the ballast water of ocean-going ships and brought to the Great Lakes in the s.

They spread dramatically, outcompeting native species for food and habitat, and by , zebra mussels and quagga mussels had infested all of the Great Lakes.

Cheatgrass, for example, is an annual grass that grows in early spring. By summer, cheatgrass is dry and ecosystems dominated by cheatgrass are more likely to catch fire. Invasive plants aren't just a Portland problem. There are regional, state and federal efforts to combat invasive vegetation. These costs are passed on to consumers through higher prices for agricultural products. For example, money a farmer spends for star thistle control in pastures is reflected in the price of your steak.

Increasing efforts to prevent and control invasions is the most cost effective and ecologically successful approach. The U. If early intervention is not implemented and a species becomes widespread, eradication may not be feasible so the damages are permanent and money is still spent to control the future spread and contain the population.

The following organizations host volunteer work parties to remove invasive plants and restore native vegetation to natural areas. Phone: Fax: Most Popular View Less.

Most Recent View Less. Van Hengstum introduces three new tools that can be applied in the risk analysis of non-native species, thus reducing the risk of invasions and the associated environmental effects.

These tools will allow us to predict the potential distribution of non-native plants, the native species likely to be affected in terms of pollination success and the types of insects sensitive to the toxins carried by some non-native species. Invasive plants are plants that have been introduced into a new area generally as a result of human actions and subsequently dispersed rapidly.

They can have a major impact on the area's biodiversity and ecology. For example, some invasive plants may outcompete native species, while others may affect sedimentation processes and the chemical composition of the soil.

Some invasive plants are weeds and cause problems in the agricultural sector. In the Netherlands, the non-native plant species Hydrocotyle ranunculoides water pennywort causes considerable economic damage by clogging up entire water systems. Van Hengstum focuses on assessing the effects of plant invasions on pollination, herbivory damage caused by insects and other organisms and invertebrate communities. He demonstrates that invasive plants can have both a positive and a negative impact on the insect visitation frequency to nearby native flowers.

Despite these effects, he did not identify any consequences in terms of seed set of the species included in the study. In most cases, plant invasions were found to reduce the abundance number of individuals and taxonomic diversity number of species of invertebrates. The opposite effect was found to occur on the edges of the invasion areas, probably due to greater diversity of food sources as a result of the presence of the invader.

The plant invasions did not affect the intensity of herbivory affecting nearby native plants. Areas with one or more exotic non-native species have a lower plant diversity than areas with exclusively native species. Van Hengstum suggests that non-native species find it easier to invade an area with a lower diversity of species.