The Black Hills, Bear Lodge Mountains, and Devils Tower - Mountains and Plains: The Ecology of Wyoming Landscapes - page 281

Appropriately, condition assessments for the federal
and state lands now consider the implications of cli-
mate change. Reports indicate that mean temperatures
in the region have risen by about 2°F during the twen-
tieth century, and models predict an increase of 5°-12°F
during the twenty-first century. As usual, there is less
certainty about precipitation, but even if it increases,
evapotranspiration will increase as well because of the
higher temperatures and longer growing season, most
likely resulting in a drier climate. All managers in the
region wonder what the effects of a warmer, drier cli-
mate will be.
the most pertinent study on the effects of climate
change was done in 2006 by U.S. Forest Service scien-
tist Gerald Rehfeldt and his associate s. 52 A fter careful
analysis of the climate required by ponderosa pine in
western north America, they applied several climate
projections for the twenty-first century and concluded
that, most likely, ponderosa pine forests will be much
less dense and widespread in the Black Hills and Bear
Lodge Mountains by 2060 and that the species will no
longer be reproducing by 2090 in some places where it
now seems to thrive—assuming unmitigated warming
continues. Mature trees can tolerate considerable tem-
perature and drought stress, but as they die from old
age, beetle epidemics, fire, wind, or timber harvesting,
the establishment of new seedlings will become less fre-
quent than now because of the changing climate. Simi-
larly, although aspen is the most widely distributed tree
in north America, some think that much of the Black

Hills is marginal habitat for this species and that it also
could become less common . 53 the magnitude of such
changes can be debated, but the trends are the same.
in general, future forests are likely to be much different
than today's.
As trees die from various inevitable disturbances, it
would be ideal if landscapes could be restored to a condi-
tion that maintains the populations of sensitive species,
such as aspen. Will that be possible with a warmer and
drier climate? can the changes that are occurring be
guided so that the evolution of the native species can
continue, as they have for millennia? in fact, some sensi-
tive species may not be able to survive; others may immi-
grate if the new environment is more favorable for them.
the forests of the Black Hills and Bear Lodge Mountains
have changed dramatically before (see chapter 2).

overall, the challenges of resource management are
formidable in a landscape that has been modified by a
century of fire suppression, habitat fragmentation, fenc-
ing, and the adverse effects of invasive species. And now
managers are faced with the uncertain effects of rapid cli-
mate change. the prospect of such changes is worrisome
to many, but two guiding principles are fundamental:
conserve the diversity of native plants and animals and
maintain the productive capacity of soils. one aspect of
the Black Hills and Bear Lodge Mountains that will per-
sist is the value of such places as refugia for mountain
plants and animals in an area otherwise dominated by
the species of lowland grasslands and shrublands.