Central Appalachians systems that are limited by hydrologic regime or geological features may be topographically constrained.

Communities that require specific hydrologic regimes, unique soils or geology, or narrow elevation ranges may not be able to shift across the landscape, even if conditions are favorable. For example, high-elevation spruce-fir ecosystems are found exclusively in the highest elevations of the Allegheny Mountains, as remnant populations surviving in the coolest and wettest habitats in the region. These ecosystems, which range from wetlands to uplands, are already constrained to the highest elevations, and if habitat becomes unsuitable, it is doubtful that there will be alternate sites or that they would be able to migrate over unsuitable habitat to reach potential northern sites.