Managing non-native invasive plants

 This post contributed by Terence Houston, ESA Science Policy Analyst Many invasive species can have a domino effect of throwing an entire ecosystem off balance by diminishing native plant or animal species that function as an important resource for both natural ecosystems and human communities. According to the Nature Conservancy, the estimated damage from invasive species worldwide totals over $1.4 trillion, five percent of the global economy. Invasive species that have gained notoriety in the United States include the Burmese python, Asian carp, Northern snakehead fish,Asian tiger mosquito, emerald ash borer and  brown marmorated stink bug. Non-native  invasives from the plant kingdom can be just as damaging, if not more so. Invasive plant species have the ability to reduce the amounts of light, water, nutrients and space available to native species in an ecosystem. Their ability to affecthydrological patterns, soil chemistry, soil erosion and fire frequency can also have disastrous economic consequences for human society, particularly the agricultural industry. Federal management of invasive species is primarily handled by the United States Department of Agriculture along with the National Park Service.  According to the U.S. Forest Service, invasive exotic plants constitute eight to 47 percent of the total flora of most states in the nation. Of the approximately 4,500 exotic species currently in the U.S., at least 15 percent cause severe harm. Examples of the detriments of invasive plants include alteration of food webs, degradation on wildlife habitat, changes of fire and hydrological regimes and increases in erosion rates. The Forest Service estimates that the United States spends approximately $145 million annually in its attempt to control non-native invasive plants. In a recent edition of the Ecologist Goes to Washington podcast, ESA Graduate Student Policy Award winner Sara Kuebbing discusses her work on invasive plant species at the University of Tennessee in Knoxville. In addition, Kuebbing serves on the Tennessee Exotic Pest Plant Council (TN-EPPC). Her work has included some of the most problematic invasive plant species in the state of Tennessee and the greater United States. During the podcast, Sara touches on her research and efforts by TN-EPPC and affiliated state entities to educate communities on invasive plant species and manage both existing and potential threat species. Perhaps among the most renowned invasive plant species is kudzu, which currently inhabits 30 states and the District of Columbia. According to scientific studies, kudzu’s nationwide invasion costs about $100-500 million per year in forest productivity loss. Kudzu can grow on top of structures and even other plants, including trees, basically suffocating them by obstructing their access to light and other necessary resources.  Power companies spend about $1.5 million annually to control...

Read More

From the community: ESA annual meeting in the news

Last week at the Ecological Society of America’s (ESA) 95th Annual Meeting in Pittsburgh, scientists presented research on the foraging behavior of bushbabies, the effects of RoundUp herbicide on amphibians, the benefits of microbial communities inside the human body and the global issues surrounding invasive species, pollution, global warming, elevated nitrogen and hypoxia, among others. Here is just some of the research from ESA’s annual meeting.

Read More

Exotic plants can be water-hoggers

We often think of vegetated areas as being ecologically friendly; that is, plants are good for the environment, right? But it turns out that even that statement has caveats. In a study out in this month’s Ecological Applications, researchers have found that some exotic trees in Hawaii can use water at a rate of more than twice that of native trees. This greedy water consumption could spell trouble for the island state, where fresh water is already in short supply. Lawren Sack of UCLA and his colleagues compared the water use of trees in native forests (below), composed mostly of native ohia trees, with water use in timber plantations (left) containing exotic eucalyptus and tropical ash. The team monitored the rate of sap flow through the tree: a faster flow rate means that the tree is using more water. The team found that individual eucalyptus and tropical ash used three and nine times more water, respectively, than individual ohia trees. Since each of these forests is dominated by these three species, the team scaled up their results to predict how much water a whole section of forest uses. Even when including other native plants that use water quickly, such as tree ferns, the tropical ash forests still used water at a rate of 1,800 grams of water per square meter per day, more than 2.5 times that of the other forests. In the early 20th century, Hawaii’s non-native tree plantations were originally intended for timber production and to conserve the islands’ top soil. At the time, however, the importance of biodiversity and the dangers of exotic species weren’t as clear as they are today. Especially with climate change rapidly changing many ecosystems, Sack says, it’s vital that land management plans recognize and integrate the fact that water use by plants can affect the clean water supply. Says Sack: When making decisions to restore a native forest or preserve or establish a plantation, we need to do a more detailed valuation that includes the cost of water they’re using. There are a lot of reforestation projects underway to take up carbon dioxide from the atmosphere, where people are prioritizing fast-growing trees. But we shouldn’t let alien plants sweep over native forests. Our findings make a clear case that we need to know how much water landscapes are using and conserving. Photos: Aurora Kagawa Kagawa, A., Sack, L., Duarte, K., & James, S. (2009). Hawaiian native forest conserves water relative to timber plantation: Species and stand traits influence water use Ecological Applications, 19 (6), 1429-1443 DOI:...

Read More