According to a report released Sept. 10 by the United States Forest Service, the number of dead trees on 750 million acres of public and private forests across America is on the decline for the second straight year.
The report, Major Forest Insect and Disease Conditions in the United States: 2011, showed that most of the reductions were in western states. Though mountain pine beetle infestation has long affected the area, acres of forests with dead trees resulting from the beetles declined from 6.8 million in 2010 to 3.8 million in 2011. This is largely due to the fact that they have almost depleted their preferred food source, the lodgepole pine.
The mountain pine beetle is not alone in its attack on forests. The spruce beetle, the most significant natural enemy of the spruce tree, has caused four consecutive years of increased mortality, with dead trees found on 428,000 acres nationwide. The fir engraver, common in western coniferous forests, is responsible for tree deaths on approximately 323,000 acres, most of which are in California. Death of subalpine fir, caused by beetles and other mortality agents, was found on more than 274,000 acres. And as the mountain pine beetle is forced to seek another food source, the ponderosa pine and high-elevation white bark pine will be at risk.
In eastern states, tree death due to insects and disease continues to remain low, with southern pine beetle-caused mortality at historically low levels. The southern pine beetle outbreak in New Jersey declined from 14,000 acres in 2010 to about 6,700 acres in 2011. However, that number is still considered very high for the state. Invasive forest diseases and insects, such as the emerald ash borer and the Asian long-horned beetle also remain a big threat to eastern forests.
From StGeorgeUtah.com: https://www.stgeorgeutah.com/news/archive/2012/09/23/forest-service-fewer-trees-dying-nationwide/