Mountain grasslands cover about 80,000 acres at elevations above 9,000
ft, and are surrounded by or interspersed with mixed conifer forests.
Climatic data from Seven Springs and the nearby station at Burro Mountain,
within a mixed conifer stand, were compared to determine feasibility of
using windbreaks in these grassland sites. Soil analyses indicated that
the main difference between forest and grassland soils was the lack of
mycorrhizae in the grassland soils (Thompson
et al. 1976). Temperature data from Seven Springs and Burro Mountain
were similar. Annual precipitation at Seven Springs average 22 inches
while Burro Mountain average 32 inches, but high winds on the grasslands
may have resulted in inaccurate gage readings. Thompson
and others (1976) believed that lower available soil water, related
to snowpack sublimation, was one reason that trees had not moved into
the grasslands. Trees are found at the edges of the grasslands where topography
shelters them and the snowpack from wind; moderating the microclimate.
Water-yield augmentation is no longer a primary management goal in the
Southwestern United States. Even timber production has declined as other
resource values, such as recreation and concerns about rare and endangered
species, have incresed.