Editing Climate and Biodiversity (section)

== Range Shifts: The Spatial Response ==

As local climates warm, the geographic areas that provide the optimal thermal and moisture conditions for a specific species (its climate envelope) physically move. To survive, species must track their required climate, leading to massive, global redistributions of flora and fauna known as '''range shifts'''.

=== Latitudinal and Altitudinal Migration ===
Generally, organisms are shifting their ranges poleward (toward higher latitudes) or upward in elevation (toward higher altitudes) to escape warming temperatures. Terrestrial species are migrating up mountain slopes, while marine species are moving toward the Arctic and Antarctic. However, this spatial response is heavily constrained by the '''climate velocity'''—the speed at which a species must move across the landscape to maintain a constant temperature.

=== Barriers to Migration and Symbiotic Limits ===
Unlike the slow climatic shifts of past geological eras, modern climate velocity frequently outpaces the physical dispersal abilities of many organisms. This is particularly challenging for long-lived, sessile organisms like trees. 

Furthermore, migration is rarely an independent process. The movement of terrestrial plants, for example, is heavily governed by the distribution of below-ground symbiotic partners. A tree species cannot successfully establish in a new, cooler northern range if the specific mycorrhizal fungi required for its nutrient uptake are absent from those soils. These hidden dependencies act as invisible limits on migration, highlighting how complex interactions define geographic ranges. Additionally, human-constructed barriers—such as agricultural expanses, highways, and urban centers—heavily fragment the landscape, cutting off natural migration corridors.