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Blue oak woodland with an annual grass understory in the foothills of Sequoia National Park. © Photo by William C. Tweed. |
Along the western edge of the parks, the vast
grasslands of the Great Central Valley give way to
blue oak savanna and a mosaic of chaparral types.
Unlike most of the park vegetation, which is made up
of plant species native to the region, the foothill
grassland is composed primarily of non-native annual
grasses which were introduced to California during
the mid nineteenth century and have subsequently
become naturalized. The slow-growing, gnarled blue
oaks that dot this landscape can be hundreds of years
old.
Dominated by dense thickets of sclerophyllous (thick
leaved) shrubs,
chaparral communities are
characteristic of lowland Mediterranean climates,
where winter rains provide most of the precipitation
and, but for the hot dry summers, temperatures are
relatively mild. Many of these species exhibit
specific adaptations to fire and drought, both of
which have a strong influence on life in the foothill
environment.
Unlike many of the coniferous forests of the world,
which are dominated by a single species of tree, the
mixed coniferous forests that cloak the lower and
middle montane slopes of the Sierra Nevada support a
remarkable diversity of tree species. Here ponderosa
pine, incense cedar, white fir, sugar pine, and
scattered groves of giant sequoia intermix and
coexist. These trees, many of which reach tremendous
heights, form some of the most extensive stands of
old growth coniferous forest that remain in the
world.
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Red fir forests grow in pure stands in the mid to upper elevation forest belt (7,000 to 9,000 feet) of Sequoia and Kings Canyon National Parks. These stately trees typically form a dark forest with scant ground cover. © USGS photo by Linda Mutch. |
In the upper montane, the mixed coniferous forest is
replaced by nearly pure stands of red fir and
lodgepole pine. Characterized by deep snow
accumulation during the winter months and a dense
canopy that limits the amount of sunlight that
reaches the forest floor, the red fir forests lack a
diverse herbaceous component. Only the most shade
tolerant herbs thrive beneath the towering trees.
Lodgepole pines have an unusual distribution, growing
in both moist lowlands and in drier sites on benches
and ridges. In wetter sites, these forests can
support a rich amalgam of herbs and wildflowers in
their understory.
Above the upper-most edge of the montane forests,
subalpine woodlands define the limit of tree life in
the Sierra. In Sequoia National Park, these include
the southernmost populations of foxtail pine, a close
relative of the long-lived bristlecone pine which can
be found in the White Mountains to the east. Downed
pieces of foxtail wood can persist intact for
thousands of years, preserved by the extremely cold
and dry conditions that characterize the high
elevations. To the north, stands of whitebark pine
provide a critical food source for the ubiquitous
Clark's nutcracker.
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Foxtail pine grow in scattered stands on bare rocky slopes at high elevations. Exposed to extremes of temperature, unlimited sunlight, severe winds and storms, and long summer droughts, these trees have shapes sculpted by the elements. © Photo by Anthony Caprio. |
Where soils are too saturated or shallow to support
tree growth, numerous meadows can be found in the
montane, subalpine and alpine zones.
Wet meadows
support a remarkably diverse assemblage of grasses,
sedges and wildflowers, which provide essential
habitat for many small mammals, birds, and insects.
Dryland meadows, too, are an important source of food
and shelter for animals of the higher elevations.
In the rocky alpine, where the short growing season
and harsh winter conditions exclude all but the
hardiest of plants, stunted trees give way to
low-growing, perennial herbs. Here plants often form
ground-hugging mats or hummocks to take advantage of
the warmer surface temperatures. In winter, the
snowpack provides insulation from sub-freezing
temperatures and desiccating winds. During the brief
summer, when freezing temperatures and snowstorms
remain a threat, surprisingly
showy flowers burst
forth in the race to set seed before winter returns.
The parks vegetation management programs focus on understanding the parks flora and vegetation, protecting rare species, restoring natural fire regimes to forest and chaparral ecosystems, monitoring and controlling invasive non-native (exotic) plants, restoring disturbed habitats and landscapes, and monitoring and managing impacts from recreational and administrative uses. Brief overviews of these programs are found on the following pages, along with suggestions for additional sources of information.
Last updated March 15, 2005
Email Contact: sylvia_haultain@nps.gov
http://www.nps.gov/seki/snrm/vegetation/vegetation.htm