As the holidays approach, some of us will be decorating our
homes with a tree native to mountains of western North America, the White
fir (Abies concolor). This species is
fairly common throughout the Rockies, Cascades and Sierra Nevada Mountain
Ranges. It can also be found in much more unusual locations, including the mountains
of the eastern Mojave Desert.
If you’ve been to Hawaii and have seen the unique native
plants that grow there, you probably know that isolated islands in the middle
of the ocean often harbor unique species and ecosystems. A similar effect
happens in the mainland southwestern US, with high mountains ‘islands’
surrounded by an ‘ocean’ of desert. These places have been dubbed sky islands, and harbor unique ecosystems.
These ecosystems often contain endemic
species, meaning that they can only be found in these isolated areas. Equally
interesting, sky islands also often contain disjunct populations and relict
species. Disjunct population is a
term used to describe populations of species that occur far outside of their
normal range. A relict species was more
common on the landscape in the past, but due to a changing climate it is now
restricted to a very small area.
Three mountain ranges in the eastern Mojave Desert within
California are considered sky islands; the Kingston Mountains, The Clark
Mountains, and The New York Mountains. These ranges all rise above 7000 ft. and
contain ecosystems that exist nowhere else in the surrounding lower elevation
desert. This fall we took a trip to
visit these sky islands and assess the disjunct, relict populations of white
fir which occur in the mountains.
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| The Kingston Mountains, a Mojave Desert sky island |
The populations of white fir in the high elevation mountains
of Mojave Desert are part of relict ecosystems which supports patches of
coastal vegetation, remaining from a wetter past in the west. A number of plants
which are more commonly found in the areas of California west of the mountains
also have disjunct populations here. These include coffee berry (Rhamnus californica) and Mexican
manzanita (Arctostaphylos pungens).
These plants and other’s such as narrow leaved yerba santa (Eriodicyton angustifolium) harken back
to an era when much larger areas of the southwest looked more similar to the
coastal charparral vegetation that we see in California today.
The main focus of our trip was to scout the white fir
populations in the hopes that we can collect seeds next season and to record detailed
information on their health. Occurring in these extreme conditions, and living
a relatively long life, these trees can provide a great study system to see how
climate change is affecting the mountains. A major concern is that climate
change will increase the temperature of these areas and literally push the
white fir, and the many other unique species that are adapted to this cooler
habitat off of the top of the mountain and into oblivion.
During our trip, we visited all three of these ranges, but
due to time constraints were only able to hike to the population in the New
York Mountains. Part of the challenge of working in these areas is their remoteness.
They occur at the tops of rugged mountains far from any trails or roads.
On our day in the New York Mountains we were joined on in the field on that day
by Andrew Kaiser of the Mojave National Preserve. After a challenging hike up
the steep southern face, we made it to the main ridge. The views were
incredible, but as we arrived and spent some time looking, but did not see any
of the large and obvious trees.
After about an hour of searching among the treacherously
steep slopes, we finally saw a large white fir crown rising above the granite
boulders. We spent the next several hours taking detailed notes, GPS data and
photos. In total, we counted 31 trees, the exact number that was recorded by a
team who visited the population in the late 70s, which included the late RSABG
herbarium curator emeritus Robert Thorne.
This, plus the fact that found plants ranging from a foot tall to 60
feet was an encouraging sign that the population is not in obvious decline. In
2016, we hope to return to this population, along with the populations in the
Kingston and Clark mountains, to do more monitoring, and hopefully make a
collection of seeds for the RSABG seed bank.
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| A young white fir specimen in the New York Mountains is an encouraging sign that the population will persist into the future |
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| Looking up the steep northern face of the New York Mountains at a stand of white fir |
The sky islands of the Mojave are one of the hidden
treasures that exist in the California desert. With nowhere to migrate to if
conditions change, a warming climate is especially threatening to the plants
and animals of these isolated areas. We hope that in the coming field season,
we can gather more data on these special places to help to develop a better
sense of how climate change will affect the Mojave Desert Mountains.
