HIGHLIGHTS from the March editions of ESA journals
The press tips below highlight research in the ESA journals Frontiers in Ecology and the Environment, Ecology, Ecological Applications and Ecological Monographs.
1. Fuel removal and prescribed burns reduce wildfire severity but may invite invasives
This invited feature compares the effectiveness of fire fuel reduction methods under the U.S. National Fire and Fire Surrogate Study. Four articles examine the effects of prescribed burns, mechanical treatment (usually thinning of the smallest trees) and a combination of both with control plots at 12 study sites in forests across the United States.
Many U.S. forests once experienced frequent natural fires that removed many of the low-lying plants, including downed woody plants, shrubs and grasses that fueled these burns. But human activities, such as livestock grazing, preferential logging of large trees and outright fire suppression or exclusion have led to changes in forest structure. Increases in tree density, smaller tree size and increased fuel load place as many as 10 million hectares of U.S. forest at high risk of hazardous fires, the authors write.
Under extreme weather conditions, the authors found that prescribed fire alone, a combination of prescribed fire and mechanical fuel removal, and fuel removal alone were all effective at reducing fire severity. More specifically, they report that to quickly restore forests with few, large-diameter trees, a combination of prescribed burns and mechanical fuel removal achieved the best results.
The authors note, however, that this combination treatment also favored nonnative species invasions at some sites. In addition, a combination of prescribed burns and mechanical thinning increased the incidence of tree death from bark beetles and wood borers. Still, the authors emphasize that a no-treatment option is not sustainable in these fire-prone environments. They recommend caution and case-by-case assessments of best management practices for different forest types.
McIver J., A. Youngblood, S. L. Stephens. (2009) The National Fire and Fire Surrogate Study: ecological consequences of fuel reduction methods in seasonally dry forests. Ecological Applications 19:283-284. Full feature: pages 283-358. doi: 10.1890/07-1785.1
2. Including environmental data improves effectiveness of invasive species range predictions
Predicting the future spread of invasive species presents a challenge to ecologists that has until recently only been addressed by comparing species climate tolerance with established climate maps to predict susceptible areas. A new study finds, however, that when land-use and habitat data are incorporated, models predict that species may also be likely to colonize areas with unfavorable climates.
Inés Ibáñez of the University of Michigan and her colleagues examined not only historical and current climatic data, but also historical environmental information from both the native and invaded ranges of three New England invasive plants: Japanese barberry, bittersweet and winged euonymus (or burning bush). The models took into account human development, disturbances and agricultural land use; habitat measures of local ground cover, such as forest type and wetlands type, were also included.
The researchers found that although climate plays a large role in predicting invasive species distribution, the inclusion of land use and habitat data improve the explanatory power of their models. In some instances, the combination of an unfavorable climate with a suitable landscape cover increased the probability of species establishment. On the other hand, some areas with favorable climates became less so when their unfavorable habitat data were included.
Most importantly, the researchers write, their models can be modified and used in other systems to predict biological invasions anywhere in the world.
Ibáñez I., J.A. Silander Jr., A.M. Wilson, N. LaFleur, N. Tanaka, I. Tsuyama. (2009) Multivariate forecasts of potential distributions of invasive plant species. Ecological Applications: Vol. 19, No. 2, pp. 359-375.doi: 10.1890/07-2095.1
3. A change of lighting could drastically reduce bird death by collision with communication towers
Each year, it is estimated that millions of birds collide with communication towers. Joelle Gehring of the Michigan Natural Features Inventory at Michigan State University and her colleagues discovered that a simple alteration of the lighting scheme on these towers may reduce bird mortality by as much as 71 percent.
The authors compared avian fatalities, mostly of tropical migrating songbirds, at towers equipped with different combinations of red and white strobe-like, flashing or steady-burning lights. The researchers found fewer dead birds under towers equipped with only red or white flashing lights. Towers that were lit under the current Federal Aviation Administration (FAA) regulations of a combination of red flashing and non-flashing lights had significantly more avian fatalities than those lit only with flashing lights.
The authors point out that a change of this type would be of little cost to the tower owners, since most of the lighting infrastructure is already in place.
Gehring J., P. Kerlinger, A.M. Manville II. (2009) Communication towers, lights, and birds: successful methods of reduce ng the frequency of avian collisions. Ecological Applications: Vol. 19, No. 2, pp. 505-514.doi: 10.1890/07-1708.1
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