Shifting species on land

By Rachel Berman

Don’t white rabbits usually live in snowy environments? Spring is coming earlier as temperatures warm, and this rabbit no longer blends in. Credit: L. Scott Mills et al., PNAS Early Edition(2013)

Marine species are moving and are especially sensitive to temperature changes in the ocean, but what about species on land? Of course there are mammals, but there are also plants, trees, birds, insects, reptiles, and many more.
You would look at a tree or plant and wonder how such a large, stationary object could move in response to unfavorable climate conditions. A tree might not be able to pack up and move, but its seeds can. Because seeds take a while to grow into new trees, this creates an interesting issue of “lag” that plants experience. Weedy, often non-native plants that have a shorter lifespan and longer seed dispersal are more likely to keep up with their favorable climate conditions. This can create novel combinations of species, with new species moving into a region before the old ones move out.
Birds certainly have it easy: they can fly to another place whenever they want, right? Relocation and expansions of range have been observed for many bird species in North America. Still, one in eight species of birds are at high risk of extinction. A bird can travel miles to escape unwanted temperatures or precipitation levels, but a new place might not have the same nesting opportunities, food, or other resources that a species requires to survive.
For all organisms, climate change is also challenging to adapt to because it affects the timing of temperature-related events during the year. Temperature changes affect precipitation like snow and rain, and also affect seasonal cues. Many biological events are directly associated with temperatures and seasons; this cyclical timing is called phenology. Bees and flowers appear at the same time in part because their individual cyclic seasonal timing has become synchronized. While bees have been emerging earlier in the year to feed, flowers have also been blooming earlier.

For more reading: