Tiny insects that feast on juvenile pinon pine needles can have a dramatic impact on soil microclimates, which can cause a cascade effect sufficient to cause changes on a far greater scale. In a study conducted in northern Arizona by a team led by Oak Ridge National Laboratory's Aimee Classen, researchers found that scale insects like those found on house plants reduced foliage of susceptible trees by 39 percent. Because of the reduction in this leaf area index, soil moisture and temperature beneath the susceptible trees increased by 35 percent and 26 percent, respectively. These and other changes in the microclimate below the affected trees were similar to predicted climate change scenarios over the next century and are sufficient to drive changes in the ecosystem process. Classen and colleagues from Northern Arizona University also found evidence supporting the notion that genetic resistance to insect herbivory occurs in the tree population. This study, published in Soils Science Society of America Journal (November-December 2005), is the first of its kind and could serve as a model for the effect bark beetles and other outbreaking insects have on defoliation and devastation of forests and, ultimately, climate change. In the U.S., insects and pathogens cause damage estimated at more than $2 billion per year.
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