Forested watershed

All global climate models project that temperatures in New England and northern New York will increase over the next century as a result of continued increases in atmospheric greenhouse gas concentrations.

Drier conditions could also increase the risk of duff fire, previously not a threat except after extreme anthropogenic disturbances.

Complex topography may provide cool pockets of habitat, such as in high-elevation valley bottoms, where this ecosystem would be likely to persist.

Insect pests such as the hemlock and balsam woolly adelgids currently affect this ecosystem and have the potential to increase when winter temperatures no longer limit populations.

Although this ecosystem generally receives the highest rainfall in the Central Appalachians, a decrease in precipitation, combined with higher temperatures, may negatively impact spruce regeneration.

Changes in winter processes could affect this high-elevation ecosystem more than others; interacting effects of reduced snow cover (warm temperatures) or increased snow cover (lake effect) would alter soil freezing conditions.

Suitable habitat for this ecosystem is already limited to the highest elevations in the Central Appalachians and the range of this ecosystem may contract as climate change forces species upward. This ecosystem is dependent on very moist conditions, and persists only in the coolest, wettest, and highest elevation sites in mountainous sections.

Red spruce and balsam fir (the keystone species in this ecosystem) are limited to the Allegheny Mountains and the Northern Ridge and Valley sections, and models project suitable habitat and growth potential to decline dramatically for both species under both climate scenarios. Balsam fir has the lowest adaptive capacity of all the species in this ecosystem, largely due to its fire- and drought-intolerance and susceptibility to balsam woolly adelgid and other insect pests.

In the cooler and moister sites, hemlock is a keystone species that has been declining and is projected to decline further. For these forests, the loss of hemlock is likely to change the species assemblage dramatically, with fast-growing generalists like red maple or a variety of invasive species likely to overtake the newly vacated niche.

Increased flashiness followed by dry periods could cause amplification of the current hydrologic cycle, potentially increasing the spread and establishment of current and newly introduced invasive species.