Global Climate Change

Current Stresses Facing our Forests

Global climate change is playing a key role in the threats that are facing our forests, including drought, pest outbreaks, fires, and higher stress factors {increased temperatures, diseases and air pollution}. The past several summers have lacked adequate levels of moisture, which coupled with higher temperatures have placed significant stresses onto our forests. Trees including the southern pines and the upper Midwest’s hardwoods are experiencing extensive damage due to their susceptibility to new pathogens causing spreadable diseases and insects (pests). Forests are being directly affected by changes in atmospheric carbon dioxide and climate. In a state where there is adequate water and nutrients, increases in atmospheric CO2 may enable forests to become progressively prolific such as in the Northeast region. Growth in the West and Southeast on the other hand will not escalate from increased levels of CO2, since there is a limited amount of water available producing an inadequate amount of photosynthesis.

Other damaging effects of global warming on our forests include growth loss, defoliation, modified tree physiology, timber damage, lowered defense mechanisms and potentially large forest/species diebacks. Global climate change has already shifted the habitats of several forest insects, including the gypsy moth (which are reactive to precipitation change) and the mountain pine beetle. A rising concern is whether or not the majority of tree species within our forests will be able to tolerate these outbreaks/migrations of insect population. An example given is of the mountain pine beetle. Through only a warming of two degrees Celsius, populations of these beetles could thrive to a level that threatens the Rocky Mountain White bark Pines, which are accountable for feeding the surrounding wildlife.

There are numerous natural systems and human systems affected by global climate change. Global warming poses serious threats to the dimensions of geographic ranges for various tree species throughout the U.S. and worldwide. Roughly 40 percent of the Mid-Atlantics forests have lost their tree canopy cover over the years. Other forested areas that have taken major hits in global climate change include the Great Lakes, the southeastern coast, southern Appalachia, and to a lesser degree the Rocky Mountains and the Sierra Nevada. It is believed that in the future, no temperate forest even in North America will truly be wild and native. Particular forested habitats will likely begin to lose diversity of tree species as they begin moving northward or to higher altitudes. This occurrence could pose risk to tree species not only on a local basis but possibly even a regional basis i.e. mountaintop tree species have nowhere higher to go if the climate became unsuitable for them. Along with exposed high stress factors, the trees life-cycle reproductions are also

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