Invasive Species
Common Bugle - Ajuga reptans L.
 

Common Names: common bugle, creeping bugleweed, carpet weed, carpet bugleweed

Native Origin: Europe and Asia

Description: An erect herbaceous plant in the mint family (Lamiaceae) growing up to 12 inches in height when in flower in mid-Spring, but 2 to 4 inch tall in Summer, Autumn, and Winter. The stems are 4-angled and densely pilose (covered with fine hair) above and less below. Leaves are approximately 2 ½ inches long and 1 ½ inches broad, opposite, toothed, oblong to obovate and glabrous or sparsely pubescent. Leaves and stems are green to deep purple in color. Whorls of 4 flowers are arranged in terminal spikes, and pollinated by bees, butterflies and moths. Flowers bloom from April to July producing small blue-purple, tubular blossoms and small brown 1-seeded nutlets. It reproduces by repent stems (leafy runners) and seeds.

Habitat: This semi-evergreen groundcover is found invading lawns, roadsides, fields, meadows, and woodlands with partial sun to full shade. Plants prefer moist, well-drained soils of average fertility, but can adapt to poor soils and high temperatures.

Distribution: This species is reported from states shaded on Plants Database map. It is reported invasive in MD, TN, and VA.

Ecological Impacts: It is a slowly invasive prostrate groundcover that forms mats. It invades beyond its originally intended boundaries by sending out creeping, rooting stems that moving into adjacent areas.

Control and Management:

  1. • Manual- Cut, shear or weed-eat flowering stalks to prevent seed dispersal. Dig up runners and/or shallow roots twice a year.
  1. • Chemical- It can be effectively controlled using any of several readily available general use herbicides such as glyphosate or triclopyr. Follow label and state requirements.

References:
www.forestimages.org
http://plants.usda.gov
www.nps.gov/plants/alien/list/a.htm
www.missouriplants.com/Blueopp/Ajuga_reptans_page.html,
www.hcs.ohio-state.edu/plantlist/description/aj_ptans.html
www.ibiblio.org/pfaf/cgi-bin/arr_html?Ajuga+reptans&CAN=COMIND
http://wisplants.uwsp.edu/scripts/detail.asp?SpCode=AJUREP


 
Distribution Map
 

Trends and rising threats from invasive species
Humans intentionally and unintentionally spread invasive species. The foundations of agriculture and animal husbandry are based on ancient habits of selectively favoring some plant and animal species and their habitats over others for food, fiber, and medicine (Flannery 1973). According to Pimentel and others (1999), about 50,000 non-native species have been introduced in the United States. Many nonnative species have been deliberately introduced for erosion control (kudzu), food animals and fish (brown trout), agricultural crops (Johnson grass), and ornamental trees and landscape plants (purple loosestrife). Some insects and diseases have been introduced in ignorance, as was the Gypsy Moth, or as the unintentional result of a global economy, as with the West Nile virus and Zebra mussels (Pimental and others 1999). Many invasive plants in the United States were originally introduced for food, fiber or erosion control, or as ornamentals. For example, purple loosestrife was introduced as an ornamental in the early 19th century. Loosestrife is present in riparian areas throughout the continental United States and control costs are an estimated $45 million per year. Riparian areas are extremely valuable to native plants and animals, and the wholesale invasion by Loosestrife poses a serious threat of eventual extinction to numerous riparian-dependent species (Pimentel and others 1999).

Other plant species, such as European Cheatgrass, have almost entirely displaced sagebrush-grassland plants and associated animals. Cheatgrass has also seriously altered the fire regime from an average return interval of 60-110 years to 0-3 years. Cheatgrass is an example of the adverse impacts an introduced species can have on the environment. Some scientists estimate that Cheatgrass is present on 100 million acres of grassland-steppe in the western United States. Cheatgrass forms a dense, uniform carpet that out-competes native grasses and shrubs. It greens quickly, dries quickly and produces a very flammable cover that often burns completely, without allowing native plants to reestablish. In pinyon-juniper woodlands, the combination of Cheatgrass and fire may effectively prevent the re-establishment of the original woodlands (Mitchell 2000).


Purple Loosestrife
Lythrum salicaria
© 2001 CDFA


Rana aurora draytonii
California Red-
Legged Frog
© 2002 Pierre Fidenci

  

Invasive species cost the public approximately $137 billion per year in damage, loss, and control (Pimentel and others, 1999). The economic losses are significant but the ecological and cultural losses of native flora and fauna are equally important. For example, the bullfrog, a nonnative species in California, has almost completely replaced the native California red-legged frog--the famed jumping frog of Calaveras County. Another introduced plant, the Giant Reed, eliminates native streamside vegetation and dries up creeks that provide habitat for four endangered species: least bell’s vireo, southwestern willow flycatcher, California red-legged frog, and unarmored three-spine stickleback (USDA Forest Service 2003a).

Approximately 46% of the plants and animals federally listed as endangered species have been negatively impacted by invasive species (Wilcove and others 1998). Introduced insects and disease have also taken their toll on the environment. Chestnut Blight and Dutch elm disease are two well-known examples. Gypsy moth was intentionally introduced in the 1800s as a possible source of silk production. As a result of these well-known pests, the American chestnut and American elm have virtually disappeared from the US landscape and numerous other eastern trees are at risk from Gypsy moth (USDA Forest Service 2001).

What is the role of the Forest Service?
The Forest Service Chief has recognized the threat that invasive species pose to forest health, the economy, and the mission of the Forest Service. The interaction between the invasive species threat and other significant threats needs to be considered. For example, accidental spread of invasive species by unregulated OHV use, the spread of invasives on newly burned areas, and the wide swaths of some invasives that fragment habitats are obvious interactions. The invasive species issue is broad and impacts almost all terrestrial and aquatic habitats nationwide.

Law and policy governing invasive species
Managing and controlling invasive species requires an extraordinary coordination of programs, research, and management actions at the federal, state, and local levels. Invasive species affect all land ownerships and jurisdictions. The U.S. Department of Agriculture alone has six agencies involved in the control of invasive species (Tenny 2002). The Federal Noxious Weed Act of 1974, as amended (7 U.S.C. 2801 et. seq.), 36 C.F.R. 222.8, Departmental Regulation 9500-10, and Forest Service Manual 2080 outline agency responsibilities for noxious weed management. (Note: not all legally defined “noxious weeds” are non-native invasive plants.) FSM 2080 provides guidance to the National Forest System to address the more narrowly defined “noxious weed management”. Forest Service responsibilities and management direction for the control of insects and disease are listed in the Cooperative Forestry Assistance Act of 1978 (92 Stat. 356; 16 U.S.C. 2101) and Forest Service Manual 3400.

In 1999, Executive Order 13112 created the National Invasive Species Council (NISC) co-chaired by the Departments of Agriculture, Commerce and Interior. The executive order recognized the ecological and economic threat posed by invasive species and directed a broad intergovernmental effort to address invasive species problems (National Invasive Species Council 2001). An Invasive Species Advisory Committee of non-federal representatives was appointed by NISC to provide advice and information to federal agencies. NISC’s Management Plan, published in 2001, set nine goals including prevention, early detection and rapid response, control and management, restoration, international cooperation, research and education (NISC, 2001).
 

The Forest Service is developing a comprehensive national strategy to alleviate the impacts and reduce the threat from exotic invaders (Forest Service 2003). Invasive species control is also addressed in the agency’s strategic plan under “Goal 2: reduce the impacts from invasive species” (USDA Forest Service 2003b). The objective under this goal is to “improve the effectiveness of treating selected invasive species on the Nation’s forests and grasslands.
 

Invasive Species on National Forests / Invasive Plants
The United States has about 2,000 non-native invasive plant species, which are concentrated in California, Florida, and Hawaii (Mitchell 2000). On non-croplands in the midwestern states, one Forest Service researcher estimates that 14 percent of the plant species are non-native invasive plants. Trend data from the 19th century to the present indicates a significant escalation in the percentages of non-native invasive plants in the last half of the 20th century (Mitchell 2000). An estimated 3.5 million acres of National Forest System lands are infested with invasive weeds, according to the 2000 RPA assessment, which summarized local estimates from individual national forests(USDA Forest Service 2001). However, local estimates vary widely, and the agency lacks a comprehensive inventory for either terrestrial (land) or aquatic areas infested with invasive species. The Framework for Invasive Species calls for expanding inventory and monitoring activities to identify more invasive insects, pathogens and plants (Forest Service 2003).
Some species of particular concern to Forest Service managers are leafy spurge, knapweeds and starthistles, saltcedar, non-indigenous thistles, purple loosestrife, and cheatgrass in the West and garlic mustard, kudzu, Japanese knotweed, Tree-of-heaven, and purple loosestrife and hydrilla in the East (Mitchell 2000).

Insect Damage and Disease
Insect damage and plant disease are natural disturbances that are part of a healthy, functioning ecosystem, along with fire and wind damage. However, both native and non-native insects and diseases have caused above normal mortality rates on forested lands in the United States. Some 58 million acres or 8 percent of forested land are at risk for mortality rates that exceed the norm by 25 percent or more (USDA Forest Service 2001). High mortality rates can accelerate the development of high fuel-loading in fire-dependent forests, effectively remove important ecosystem elements, and reduce private property values. The highest profile exotic insects and diseases include Asian Longhorn Beetle, Emerald ash borer, Dutch elm disease, chestnut blight, white pine blister rust, Port-Orford cedar root disease, European gypsy moth, hemlock wooly adelgid, and beech bark disease. Aside from the potential economic loss from timber volume, many wildlife and fish species are dependent on the ecosystems affected by these invasive insects and diseases (USDA Forest Service, 2001).

International context
Invasive species negatively affect natural ecosystems throughout the world by out-competing native flora and fauna for resources and growing space. Because there are often no biological controls on their growth, invasive species spread quickly and negatively impact threatened and endangered species. At least 4,500 nonnative plant, animal, and microbe species were established in the United States during the 19th century, and about 15 percent of these are considered harmful (Eav 1999).

Many invasive species arrive in the United States through international trade. Therefore, the Forest Service must work with international partners to (1) stem the flow of invasive species into the country, (2) discern and apply biological controls for invasives that have already established and spread, and (3) protect island ecosystems, which are especially vulnerable due to their high percentage of unique species and evolutionary isolation.
 

 

 
 
              
 
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