Invasive Species An introduction

What is a native species? normally live and thrive in a particular community. occupy specific habitats and have specific niches in their native environment. have natural predators that help to keep their populations in check. Pink lady's slipper, Cypripedium acaule Red fox, Vulpes vulpes

What is a non-native species? species living outside its native distributional range has arrived there by human activity, either deliberate or accidental.  Non-native species are not necessarily invasive. Multiflora rose, Rosa multiflora, was introduced for use as an ornamental plant, to control erosion, and to use as “living” fences for livestock. Zebra mussels (Dreissena polymorpha), were accidentally introduced to North America, and are now found in some Pennsylvanian waterways

What is a non-native invasive species? A non-native species that adversely affects habitats and biodiversity. Emerald ash borer, Agrilus planipennis , has killed millions of ash trees in the mid-west and has recently been found in Pennsylvania Japanese stilt grass, Microstegium vimineum, becomes established on recently disturbed areas and outcompetes native plants, reducing biodiversity.

Common characteristics of invasive species Invasive species in general: Have few natural predators, competitors, parasites or diseases Rapid reproduction Fast Growth Are long-lived Are generalists (tolerate many different conditions/different foods Are pioneer species (1st to grow after a disturbance) Characteristics that make Zebra mussels a good invader include its ability to tolerate a wide-range of environments, and high reproduction rate; female mussels release up to 100,000 eggs ability to tolerate a wide-range of environments year. Discussion: how would these characteristics enable a species to become invasive?

What traits are common to invasive plant species Self-compatible Flower early Produces abundant seed Disperse seed widely Grow rapidly Spread asexually (don’t need a mate) Strong competitors Characteristics that make tree-of-heaven a good invader include its ability to flower early (within 2 years), ability to spread asexually, and fast growth rate.

Different Routes of Invasion Most invasions are due to human activities: Exotic Plant or pet trade (released/escaped) Commercial shipping (stow away on a ship or plane) Tourism Carry it in Wind- Seeds can be carried great distances. Water- Organisms can be transported on natural “rafts” Ballast Water from ships/boats In most cases of invasive species, human actions are to blame for their rapid spread. Seeds that are imported from far away can grow and multiply rapidly in the wild to establish an invasive population. For example, Japanese knotweed (Fallopia japonica) has spread across the UK, outcompeting several native plants for space and light. Similarly, animals that are considered desirable pets often escape and establish feral populations, such as the rose-ringed parakeet (Psittacula krameri) in Richmond Park, London. Ships move all over the world and have spread rats, mice and many other invasive species to numerous islands, which often has devastating effects on these islands’ biodiversity, and a particularly negative effect on nesting seabirds. Island species are very vulnerable to the threat of invasive species as many islands, such as Australia, New Zealand, Madagascar, the Hawaiian Archipelago, and the Galapagos have a high proportion of endemic and highly specialised flora and fauna which have evolved in isolation over hundreds of thousands of years. In the past, the geographic isolation of these islands has limited immigration of new species, allowing established species to evolve with few strong competitors and predators; however, with the advent of global travel and tourism, the transport of species from all over the world (both accidental and deliberate) has resulted in the introduction of invasive species to ecosystems that are often unable to cope. Islands are more prone to invasion by alien species because of the lack of natural competitors and predators that control populations in their native ecosystems. In New Zealand for example, the introduction of non-native species has caused an irreversible decline in many of the islands’ bird species, such as the kakapo, the world’s only flightless parrot. Water discharged from ships can potentially transport a huge amount of invasive species. Numerous invasive species are thought to have spread this way, including the zebra mussel (Dreissena polymorpha) and Chinese mitten crab (Eriocheir sinensis). Seeds of invasive plants can be transported hundreds of miles by cars, on clothes and under shoes. Areas that are visited more often by tourists are more likely to be at risk from the introduction of invasive species.

Major events that allow invasive species Removal of natural barriers waterfalls, wetlands, land barriers Development of larger and faster transatlantic vessels- ships cross 2 weeks, ballast water dumping Water quality improvements environmental regulation of pollution improved habitat quality

INVASIVE SPECIES PROBLEMS World-wide problem Increase in travel and trade open routes In U.S. costs $137 billion dollars per year Approximately 42% of Threatened or Endangered species are at risk due to non-native, invasive species. threaten species diversity Can cause an imbalance in the natural environment Out compete native organisms for resources Change abiotic factors Threaten agriculture Endanger the health of plants and animals

Impacts of invasive species Displace native species: Japanese stilt grass displaces native herbaceous plants, reducing biodiversity, and reducing food available for wildlife species. Monoculture of Japanese stilt grass, prevents establishment of native herbaceous species Diversity of herbaceous species increases wildlife habitat

Impacts of invasive species  Reduce ecosystem health and productivity     Monoculture of Japanese barberry prevents the establishment tree seedlings

Impacts of invasive species Some invasive species kill native species About ¼ of the hardwood trees in Pennsylvania used to be American chestnut. The invasive chestnut-blight fungus killed most American chestnut throughout the eastern US by 1950. American chestnut, Castanea dentata, at Grey Towers National Historic Site in Milford, PA, circa 1905 American chestnut infected with chestnut blight fungus, Cryphonectria parasitica

Impacts of invasive species Indirect impacts: Hemlock woolly adelgid is killing Eastern hemlock trees throughout Pennsylvania and the northeast. Eastern hemlock forests play an important role in maintaining stream temperatures and oxygen levels favorable for brook trout. Hemlock mortality leads to increased water temperatures and oxygen levels, and therefore reduced brook trout populations. Hemlock woolly adelgid Hemlock woolly adelgid infestation Hemlock mortality along stream bank

Impacts of invasive species Economic impacts: Invasive species are responsible for tremendous economic losses through loss in forest and agricultural productivity, spread of diseases that impact humans, among other impacts. European starlings, Sturnus vulgaris, spread diseases to wildlife, livestock, and humans, damage agricultural crops, and displace native birds. Their damage to agricultural crops is estimated at $800 million annually.

Invasive Species by State What area of the US has the highest # of invasive species? Why??

Controlling Invasive Species Controlling invasive species once they have become established is difficult. Control is also usually very expensive! Main ways that invasive species are controlled: Physical control Chemical control Biological control Prevention Controlling invasive species once they have become established can be difficult, and in some cases it may even be impossible. Control is also usually very expensive! There are four main ways that invasive species are controlled: - Physical control - Chemical control - Biological control - Prevention These will be discussed in more detail on the slides to follow. Image: A team of conservationists clearing Pleomele halapepe stand of invasive plants.

Physical Control of Invasive Species Controlling plants: Mechanical – excavation, weed whipping, etc. Removal of plants by hand Installation of growth barriers Controlling animals: Culling (selectively remove) Trapping and hunting Putting up barriers or fences Controlling invasive plants: There are a number of approaches to physically controlling an invasive plant species. These can range from mechanical excavation or hand removal to the installation of growth barriers to suppress or stop invasive plants encroaching onto a site. There are many things to consider when choosing an appropriate control method, and a single control method will not work for all species. For example, strimming plants can be effective in controlling some species, such as Himalayan balsam, but only if it is done to young plants before the seed heads have developed. Strimming would not be effective for woody species, such as rhododendron, as it does not affect root growth. Similarly, for species such as Japanese knotweed, strimming would result in the plant fragments being dispersed over a wide area, exacerbating the problem. Controlling animals: Culling – e.g. culling of the red deer in the UK to restrict the damage it causes to forestry, agriculture and the natural environment (e.g. browsing red deer (see photo) can prevent the regeneration of woodland) Trapping and hunting Putting up barriers or fences Image: Red deer (Cervus elaphus) feeding on tree leaves. Red deer are native to most of Europe, southwest Asia and North Africa; however, it has been introduced to Australia, New Zealand and Argentina, as well as a range of other countries, where it can cause serious damage to native species and habitats. Even in the UK, red deer are periodically culled to prevent the population becoming out of control Unintended Side Effects – may miss removing some of the invasive species

Chemical Control of Invasive Species Chemical control involves applying poison to eliminate invasive species E.g. Eradication of rats on Henderson Island Use rodenticide (rat poison) Insecticides & pesticides to control insect pests Herbicides (weed-killer) to control plants Chemical control of species: Eradication – e.g. removal of rats from islands where they are having devastating effects on nesting seabirds. A large scale eradication project was recently carried out on Henderson Island to protect the native seabirds such as the Henderson petrel, whose populations were in serious decline. As rats are extremely prolific breeders, the only feasible way to achieve the eradication of the species on a large and rugged island such as Henderson is by spreading bait containing a rodenticide (rat poison). On Henderson, Brodifacoum, the active ingredient in many household rat poisons, was used to eradicate the rats. Video – rat predating on Henderson petrel chick: http://www.arkive.org/henderson-petrel/pterodroma-atrata/video-14 Find out more about the eradication of rats from Henderson Island: http://blog.arkive.org/2010/10/rat-eradication-planned-for-pacific-island/ & http://www.rspb.org.uk/ourwork/projects/details.aspx?id=tcm:9-241934 Unintended Side Effects – may kill native species

Biological Control of Invasive Species Uses a living organism to control invasive species This organism may eat the invasive species or cause it to become diseased Biological control agents must be carefully assessed before release to ensure the control species will not become invasive itself Biological control uses a living organism to reduce or eliminate the population of the invasive species. The organism may eat the invasive species or cause it to become diseased - it relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role. Control agents are often brought from the original habitat of the invasive species. Images – L: seven-spot ladybird; R: harlequin ladybird – feeding on aphids Ladybirds are often used as biological control agents to control aphids in greenhouse production of crops. Ladybirds are natural predators of aphids, and so one way of controlling aphid numbers is to release more ladybirds into an area to help control the aphid infestation. Depending on the level of pest infestation, as many as 5,000 to 200,000 ladybirds per acre (1 to 50 per square metre) per week could be mass-released. However, biological control is risky. Proposals for biological control must be carefully assessed to ensure the control species does not become invasive and cause as much damage as the species to be controlled. One example of this is the harlequin ladybird. The harlequin ladybird spread to the UK after being imported from East Asia to Europe for commercial pest control of crops, and it is now affecting populations of the UK’s native ladybird species, as it is bigger than native species, better protected and able to outcompete native species for food resources. Seven-spot ladybird Harlequin ladybird Unintended Side Effects – control species can become invasive

LAWS & REGULATIONS – FEDERAL NISA – National Invasive Species Act - ANS “Aquatic Nuisance Species” Task Force Executive Order 13112 on Invasive Species – coordinates activities of government agencies (NCIS) The Lacy Act – regulates import and transport of species USDA APHIS – US Dept. of Agriculture Animal and Plant Health Inspection Service CDC – Center for Disease Control

What can you do? Buy native plants. When boating, clean boat before putting it into a different body of water. Clean your boots before hiking a new area. Don't take home any animals, plants, shells, firewood, or food from different ecosystems. Never release pets into the wild. Volunteer at your local park, refuge, or other wildlife area to help remove invasive species. Most parks also have native species restoration programs.