Mountain Meadows and Snowglades - Mountains and Plains: The Ecology of Wyoming Landscapes - page 229

dant with warming, partly because it has roots that tap
deep soil water late in the growing season . 24 in contrast,
the rate of photosynthesis in shrubby cinquefoil did not
increase with warming. Another heating experiment
conducted nearby found no effect of warming on plant
species composition after four growing seasons, possibly
because the earlier drying after snowmelt canceled the
benefits of warming . 25 Also, nutrients might have been
limiting to plant growth, rather than temperature or
water, as observed in alpine tundra (see chapter 14).
if nutrients are a limiting factor for plant growth,
then the effects of warming may be indirect. For exam-
ple, warming may stimulate growth only after sufficient
time has passed for warming to promote the decomposi-
tion of soil organic matter, thereby making more nutri-
ents available at a time when water also is available and
temperature conditions are favorable. invariably, mul-
tiple factors are involved. the effects of environmental
change are not always immediately obvious; long-term
experiments are required.

and biological diversity, are important sources of forage
and water, and are sensitive indicators of environmental
change. 26 With ongoing climate warming, the expan-
sion of trees into some meadows is likely to continue
where (1) desiccation does not preclude tree survival,
(2) night-time temperatures enable tree seedling estab-
lishment, (3) competition from herbaceous plants is not
excessive, and (4) scouring by winter winds is not an
important factor. the temptation to maintain some of
these meadows by tree cutting or burning may increase.
Snow may melt sooner because of warming trends, but
even low snowfall years are likely to produce enough
water to saturate meadow soils at the beginning of the
growing season. thus, mountain meadows and tundra
will continue to be green for much of the summer, even
during drought years—in contrast to lowland grass-
lands. consequently, the demand for livestock access
to this forage may increase. Ribbon forests and snow-
glades are likely to shift in their locations with changes
in the timing of snowmelt, but they will continue to
be a feature of the subalpine landscape as long as suf-
ficient snowfall and wind-caused drifting occur during
the winter.

in summary, mountain meadows are a highly valued
component of mountain landscapes. they add aesthetic