Invasive Plant News

Yes, there are!  Tarantulas, scorpions, and prickly pear cactus are native to glades in the Ozarks.  Missouri glades, which ecologists sometimes call sunlit islands in a forested sea, are areas of exposed bedrock in the Ozark woodlands that create their own hot, dry, desert-like microclimates and have their own unique mixture of species. 

Glades Cut at Tyson Research Center. Photo by Jon Wingo/DJM Ecological Services

Tiffany Knight, PhD, associate professor of biology in Arts & Sciences is leading the research.  This is a giant experiment at the Tyson Research Center, Washington University in St. Louis’ 2,000-acre outdoor laboratory for ecosystem studies.  The experiment will test three different variables in 32 glades with the goal of establishing best practices for restoring not just degraded glade habitats but degraded ecosystems in general. “We’re manipulating glade shape, we’re manipulating glade size, and we’re manipulating whether or not plant species are seeded or allowed to establish on their own,” Knight says. “Those are our three big treatments, and then we’ll judge the outcome by measuring the biodiversity and composition of plants.”

Knight plans to carry on the research for decades monitoring plant communities and in particular several rare species in the glade ecosystems.  Additional experiments will test the importance of plant and animal interactions on biodiversity, such as the impact of mammal and insect predation.  For more information see the University’s press release.

The Tree canopy in major cities has decreased by about 0.2 percent in recent years (mid-to-late 2000s).  This amounts to a loss of about 4 million trees a year.  This is the conclusion of an article, “Tree and Impervious Cover Change in U.S. Cities” by David J. Nowak and Eric J. Greenfield.  The article appears in the journal Urban Forestry & Urban Greening  (free access to full article).

Newell Park Oak Grove in Saint Paul Minnesota

As the study points out, ”trees provide various benefits associated with air and water quality, building energy conservation, cooler air temperatures, reductions in ultraviolet radiation, and many other environmental and social benefits.”  Trees therefore are vital to urban health and well-being.

Even in the one city where tree cover increased, Syracuse, the news was not necessarily good.  The tree canopy in Syracuse increased by one percent during the study period.  However, the increase was dominated by European buckthorn (Rhamnus cathertica), a nasty invasive tree/shrub.

There is now a forest “fire deficit in the Western United States. Human activities and ecological and climate changes have combined to

National Oceanic and Atmospheric Administration Image

contribute to this deficit. This is according to a recent study published in the Proceedings of the National Academy of Sciences: Long-Term Perspective on Wildfires in the Western USA.   (Free access to full article.)  The study was undertaken by an international twelve-member team.

The article observes that “fire regimes are primarily a product of climate, vegetation, topography, and human activities.”  These factors interact in a variety of ways.  One of these is the introduction of invasive plant species.

President Obama proposed to put 20,000 veterans to work over the next five years with a Veterans Job Corps conservation program.  The initiative would put up to 20,000 veterans back to work over the next five years "protecting and rebuilding America."  Specifically, as stated in a White House press release:  ”veterans will restore our great outdoors by providing visitor programs, restoring habitat, protecting cultural resources, eradicating invasive species, and operating facilities. Additionally, our veterans will help make a significant dent in the deferred maintenance of our Federal, State, local, and tribal lands including jobs that will repair and rehabilitate trails, roads, levees, recreation facilities and other assets. The program will serve all veterans, but will have a particular focus on post-9/11 veterans.”

This program harkens back of course to the Works Progress Adminstration (WPA) which spent about $40 million in the late 1930s and 1940s on work in the National Parks (about $650 million in 2012 dollars).

I will keep you posted on the progress of the Veterans Job Corp.

There are several recent articles and publications on the effects of fire on invasive plants.  Fire figures into ecosytem and invasive plant species management in two big ways. 

Wildland Fire

First, invasive plants can change the way an ecosystem responds to fire.  The September 2011 issue of the Journal of Rangeland Ecology & Management has six papers on the interplay between fire and invasive weeds in the cold desert regions of the western United States. One paper, for example, focuses on the Great Basin region and the spread of invasive cheatgrass among sagebrush sites.  Cheatgrass has invaded this area.  Because cheatgrass is fine-textured and matures early, fires have become more frequent.

Second, invasive plants can change the way an ecosystem is managed with fire.  Several publications have addressed the strategies behind using prescribed burns to control invasive plants.  See  Use of Fire as a Tool for Controlling Invasive Plants by Joseph M. DiTomaso, Matthew L. Brooks, Edith B. Allen, and Ralph Minnich Edited by Joseph M. DiTomaso and Douglas W. Johnson 2006 from the California Invasive Plant Council; Wildland Fire in Ecosystems: Fire and Nonnative Invasive Plants 2008; United States Fish and Wildlife Service, Fire Management and Invasive Plants: a Handbook 2011.