Invasive Species

Gypsy moth caterpillar outbreak taking toll on Ann Arbor trees, MLink, July , 2018UM already is taking action to respond to what it considers the biggest gypsy moth caterpillar outbreak in 20 years, and the City Council took action this week to direct the city administrator to establish a monitoring plan and budget for a summer 2018 pheromone trapping effort to monitor the extent of gypsy moths in the city.

Pennsylvania may ban this popular landscaping shrub, Public Opinion, July 6, 2018Japanese barberry (Berberis thunbergii DC) is a prickly, hardy and cheap bush small oval leaves come in colors from green to purple. Deer won’t eat it and people won’t walk shortcuts through it. The thorny plant offers protection to deer mice, the primary winter host for deer ticks, which spread Lyme disease to humans. Barberry’s dense foliage also traps humidity that ticks need to stay active. A University of Connecticut study found in 2011 that the number of ticks carrying the Lyme spirochete were more than 10 times greater in barberry thickets than areas without the bushes.

Small dogs no match for coyotes in metro Detroit, attacks on the rise, Free Press, June 4, 2018There have been several reports in recent months of dogs being killed or suspected of being killed by coyotes in the metro Detroit area.

Browse by White-tailed Deer Decreases Cover and Growth of the Invasive Shrub, Lonicera maackii, Naturalist, Apirl 2018We found leaf frequency of L. maackii in two height ranges, 0.5–1 m and 1–1.5 m, was significantly greater where deer had been excluded for 4 y. Furthermore, the basal area growth of these shrubs over 5 y tended to be higher, and the final basal area of small shrubs was significantly higher, in exclosures. These findings, along with direct evidence of deer browse from the literature, indicate deer browse on this invasive shrub is sufficient to affect its architecture and growth, and potentially mitigate its negative effect on native plants. [abstract, pdf download]

White-tailed deer browse on an invasive shrub with extended leaf phenology meets assumptions of an apparent competition hypothesis, AoB Plants, Nov 2017We estimated L. maackii comprised 14–47 % of the annual deer diet. Deer browsed L. maackii each month, but consumption was high in early spring and late summer. Crude protein of leafy twigs of L. maackii in early spring was 12.9 %, much higher than leafless twigs of native species on-site. These findings support the assumptions of the hypothesis that invasive plants with ELP impact native plants via deer-mediated apparent competition.

A SMOTHERING THREAT, MLive, Nov 1, 2017“Stiltgrass can smother and outcompete native wildflowers, forbs and grasses,” said Eleanor Serocki, coordinator for the South by Southwest Corner Cooperative Invasive Species Management Area. “It’s been a major problem in other areas, so we have to work quickly to ensure it doesn’t become one here.”

‘Cute’ urban deer eat tons of vegetation, spread disease and damage ecosystems, Pittsburgh Post-Gazette, Nov 26, 2017 At a November meeting of Friends of Riverview Park, ecologist Tim Nuttle explained that the 251-acre public space, billed by the Pittsburgh Parks Conservancy as “a jewel of Pittsburgh’s North Side,” is being tarnished by an infestation of an aggressive invasive Asian worm. The worm destroys leaf litter, threatening the growth of new plants throughout the forest. A high density of white-tailed deer, which eat young plant shoots before their roots anchor to the ground and deposit waste that feeds the worms, is exacerbating the problem.

Deer prefer native plants leaving lasting damage on forests, Science Daily, Oct 6, 2017When rampant white-tailed deer graze in forests, they prefer to eat native plants over certain unpalatable invasive plants, such as garlic mustard and Japanese stiltgrass. These eating habits lower native plant diversity and abundance, while increasing the proportion of plant communities made up of non-native species, according to a new study.

State finds new invasive weed, FreePress, Sept 2, 2017According to a news release from the Michigan Department of Natural Resources, Japanese stiltgrass has been positively identified on private property in Scio Township, near Ann Arbor in Washtenaw County. “This annual grass is considered highly invasive, taking hold in areas of disturbed soil along banks, roadways and woods,” said Greg Norwood, invasive species coordinator for the DNR’s Wildlife Division. “Seeds can be transported by water or on animals, and seeds can remain viable in the soil for three to five years. Because deer don’t feed on Japanese stiltgrass, it often takes over in areas where deer browse on native plants and leave open patches of soil.”

Fighting phragmites a never-ending battle, MLive, Aug 8, 2017Phragmites (frag-MY-teez) is an aggressive, invasive plant that grows to 15 feet in height and has had a massive impact on the ecological health of Michigan’s wetlands and coastal shoreline. Ever-expanding stands of the grass have crowded out thousands of acres of native plants across the state in recent decades, destroying food and shelter for wildlife, blocking natural shoreline views, and reducing access for swimming, fishing and hunting.

Fewer Deer, Less Garlic Mustard, Outside My Window, Dec 12, 2016It turns out that garlic mustard likes more sun than it normally gets in Pennsylvania’s summer woods so when deer over browse native plants their shade goes away and garlic mustard thrives.

Deer Discovery: Invasive Plants Get Boost from too Many Deer, Smithsonian Insider, May 6, 2016A survey of the two study plots after 25 years revealed the density of Japanese barberry, wine raspberry and Japanese stiltgrass was much higher in the open plot. The presence or absence of deer, they found, was an excellent predictor of the abundance of exotic plant species.

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