The Prime Desert Woodland Preserve is a special place within
the Antelope Valley that highlights the plants, and wildlife that
inhabit the Mojave Desert. It was established to provide visitors
an opportunity to learn about the animals, plants, and the region
in which we live. This area is protected from the encroaching
housing develpments, and is an excellent example of what a desert
woodlands resembles.
Soils of the Prime Desert Woodland Preserve By Russell
Almaraz
The soils which occur at the Prime Desert Woodland Preserve were
created by granitic stream deposits. The sand, silt and clay came
from the nearby San Gabriel Mountains. Unique plant communities
colonized these soils. The soil quality of the first 5 feet is
vital to plant growth and to most of the land uses that soils are
managed for. The soil’s differential reaction to rain and
temperature causes soil decomposition or “weathering”
to occur.
Water entering the Preserve is soaked up by the sandy soils and
enters the ground water that is stored in aquifers deep beneath the
soil’s surface. Thus, the soils of the Preserve act like a
sponge, soaking up rainwater runoff rather than contributing to
street flooding. The tributary waters of Amargosa Creek transported
the sands, silts, and clays from the mountains, and layered the
deposits on the valley floor. Over time, these deposits accumulated
and became very deep over the bedrock. Distinctive plant
communities colonized these soils and unique species occasionally
evolved. Each soil type developed distinguishing features from the
affects of climate, parent material, organisms, and time. The soil
quality of the first 5 feet is vital to plant growth and to most of
the land uses that soils are managed for. The soil’s
differential reaction to rain and temperature causes soil
decomposition or “weathering” to occur. These processes
form the characteristic features of different soil types. Soils are
classified by soil scientists according to a hierarchal
classification, or taxonomy, similar to the system used for
classifying plants and animals. A soil series name is also given.
The soils of the Prime Desert Woodland Preserve were mapped by soil
scientists of USDA’s Natural Resources Conservation Service
in the mid-1960s, and published in the Antelope Valley Soil Survey
Report.
The soils of the Joshua Tree–Juniper Woodland vegetation
community, along the North Trail complex, are named the Sunrise
Series. These sandy soils occur on an old undulating dune landscape
molded by wind. These dunes are stabilized, from further wind
erosion, by thick stands of Joshua Trees and California Juniper.
Underlying most of these soils is a hard cement-like layer,
called caliche, which resulted from rain-leached
accumulations of calcareous minerals. The upper surface of the
caliche layer can be viewed from the bridge on Joshua Tree Trail,
where the stream cut through the soil surface layer and exposed the
caliche. The hard caliche layer tends to hold rain water near the
surface, accessible to plant roots, thereby supporting a dense
plant community.
The soils of the Desert Scrub vegetation community, along the
South Trail complex, are named the Cajon and Adelanto Series. These
relatively young sandy loam soils occur on a nearly level
landscape. They have a sandy subsoil and lack a caliche layer.
Because a caliche layer is not present, rain water is quickly moved
down through the soil and out of the reach of plant roots. These
soils dry quickly, thus cannot support the dense vegetation of the
Sunrise Series. The vegetation is more widely spaced and consists
of some different species of plants which characterize the Desert
Scrub community. Joshua Trees and California Junipers occur more
scattered here.
The soil should be considered along with the Preserve’s
plants and animals, as an inseparable part of nature’s
ecosystem. Its life supporting role for both flora and fauna
provides the stage floor for the grand presentation of
nature’s show.
Riparian areas in the Preserve are even more unique, in that
most of the water flow, in the dry season, is street runoff from
the urban areas outside the boundaries of the Preserve. As the
water enters the Preserve, it often carries with it street litter
and impurities. The flowing water is “more or less”
filtered by the lush riparian vegetation growing in and along the
stream channels. Most of this water is soaked up by the desert soil
and is finely filtered by many layers of soil and geology before it
enters the underground water basin which is tapped for domestic and
agriculture uses. In this way, the Preserve serves an important
function of allowing water to enter the soil, as pavement does not
allow the water to soak in the ground. This is referred to as the
“hydrologic cycle”, in which water is used and reused
again, using nature as the transport method and as the filter to
supply clean water for many uses.
To log a find on this, answer the following questions, and
email them to me. Found it logs posted without the email, will be
promptly deleted. Do not post any of your answers in your found it
log.
- At the listed coordinates, located to the East and West of the
trail. What type of geologic feature do you see?
- At N34 40.104 W118 11.571, describe the habitat you see. Why is
it different than the majority of the preserve's habitat?
- At N34 40.206 W118 11.522, what is the large feature on the
West side of the bridge. How old is feature?
- At N34 40.127 W118 11.498 explain what is happening to the
Joshua Trees. What animal is on pictured on the sign?
- At N34 40.147, W118 11.531, (Optional) get your picture
taken in front of the Fremont Cottonwood. Post this picture with
your found it log.
- At N34 40.121, W118 11.511, what type of geological feature do
you see. Hint The answer is listed on this page.
I hope you enjoyed your visit to the Prime Desert Woodland
Preserve.
