Forested watershed
This current rebound of montane spruce-fir on the landscape may mask climate-induced migration or decline of the system in coming decades.
Lack of snowpack can result in increased risk of shallow roots freezing. Reduced snowfall and snowpack, which lead to earlier spring melt, may also play a large role in soil moisture availability. Fires are rare in this forest community, but extreme drought or tree mortality could increase fire risk.
Multiple forest impact models tend to agree that northern and boreal conifer species will decrease. Balsam fir and red spruce may not successfully regenerate if moisture is insufficient and average spring or summer temperatures exceed 92 °F. Seedling mortality may also occur during drought or if soil surface temperatures exceed 115 °F.
Protected valleys or coves may continue to provide cool microhabitats where spruce and fir persist. This forest community is projected to lose physical habitat as the climate warms and species migration is limited by complex topography and extreme requirements.
This forest community is currently recovering from historic acidic deposition and logging which significantly reduced the extent of this forest.
Increases in flooding are likely to benefit many invasive plants that are able to establish quickly and outcompete native vegetation on disturbed sites
Distributions of many common species are expected to shift on the broader landscape, but persist in these moist lowlands. Some of these species are tightly linked to moisture availability. Future projections for species in this community may have greater uncertainty because many of these species are less common and there are challenges to modeling wetland habitats. Black ash and eastern hemlock are expected to lose a large amount of suitable habitat under low and high climate scenarios.
This diverse forest community occurs over a wide range of habitats and is widespread and common throughout the interior portion of the Mid-Atlantic region. In general, areas that are north-facing, at higher elevations, or are farther north in the region are expected to undergo less change compared to forests in warmer, drier, or more southerly locations, particularly where past land use, land development, fragmentation, invasive species, or other factors have already impaired the system.
Although prolonged flooding may exceed the saturation tolerance of some species, an increased risk of drought is also a serious threat which many species are not likely to withstand. Changes to the timing and intensity of precipitation events are expected to result in increased flooding, erosion, and sedimentation during precipitation events, as well as potentially increased risk of drought between precipitation events. Hotter and drier conditions could reduce water table levels and water availability to trees.
The physical structure and function of conifer communities create the shady, cool microclimates where they thrive and there are relatively few native conifers to fill this functional role.
