Possible Effects of the Hemlock Wooly Adelgid on Hemlock Headwater Ecosystems. Allyson Kopera, 2015, Biology Department, Juniata College, Huntingdon, PA 16652.
The overall health of Hemlock Headwater Ecosystems in Central Pennsylvania is declining due to an invasion of the Hemlock Woolly Adelgid. Because the needles on the trees are falling and being affected, the whole ecosystem is suffering. With what we know about how the Hemlock Woolly Adelgid affects Hemlock Headwater Ecosystems, we conducted experiments where we could relate the biological factors that were affected with the possible presence of the Hemlock Woolly Adelgid. We investigated ten different areas surrounding Huntingdon Country and took measurements of biological factors such as canopy density and water temperature. We observed that the decrease in needles on the trees significantly affected the rest of the ecosystem either by falling aerial litter or opening up the canopy to allow more sun to penetrate the stream. All the biological factors that we measured suffered in one way or another letting us know that something is affecting these trees and the rest of the ecosystem. We concluded that the Hemlock Woolly Adelgid was present in all ten areas even though we have no direct evidence or collection of the Hemlock Woolly Adelgid. .
Biological invasions of foreign species to a new environment have the capability to alter the new environment and also change the abiotic and biotic factors in the area. Invasive species can be any kind of living organism that is not native to the surrounding area and which causes harm. Invasive species are so harmful because of the diseases they may carry, they out-compete native species for food and other sources, and also preying on the native species. Invasive species decrease biodiversity by overpopulating once they take over the native species, change food webs by destroying or replacing native food sources, and alter ecosystem conditions like changing soil chemistry.