Death of Hemlock Trees Yields New Life for Hardwood Trees, but at what cost?

With the introduction of exotic pests and pathogens, tree species are being eliminated one by one from forests ecosystems. Scientists can observe immediately how their loss affects the environment. In the eastern United States, a pest called the hemlock woolly adelgid has decimated hemlock tree populations.  We found less nitrogen leaching from the soil because hardwood trees had compensated by increasing their productivity because of the decrease in hemlock tress. The hardwood trees were able to grow because, when the hemlock trees died, phosphorus was released and became available to the hardwood species in the area. The increase in available phosphorus stimulated the growth of existing hardwood trees, which then increased tree demand for nitrogen. The hemlock woolly adelgid is host specific, meaning it only infests hemlock trees. The aphid-like insect attaches itself to a needle, sucks the sap from it and the tree dies.  "Although the hemlock woolly adelgid doesn't do well in cooler climates, it is clearly affecting hemlock populations in the Northeast as well. It's just taking longer to see the impact," Fraterrigo said from the University of Illinois."We're seeing warmer temperatures at night across the nation and warmer winter temperatures in some places. Those two factors together could allow the insect to move slowly farther north. Fraterrigo said she'd like to continue the work in the Great Smoky Mountain National Park, which has also lost hemlock and has even higher rates of atmospheric nitrogen deposition. I think it is mind blowing that one factor of a decrease in the tree population could affect the whole nation’s weather. My solution to this problem would be to eliminate all of the exotic pests and pathogens that are destroying the trees. The problem with this solution is that it may be hard to get rid of the pest and pathogens.   

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