Klamath Mountains Ecoregion
By Benjamin M. Sleeter and James P. Calzia 1
Click to see available downloads for this ecoregion
Figure 1. The Klamath Mountains Ecoregion sample bocks overlay the USGS 1992 National Land Cover Dataset.
Ecoregion Description
The
Klamath Mountain Ecoregion covers 48,538 km2 (18,740 mi2)
the Klamath and Siskiyou Mountains of northern California and southern Oregon (fig. 1). The Klamath is flanked by the Coast Range to the west, the Central and
Southern California Chaparral and Oak Woodlands to the south, the Willamette Valley to the north, and the Cascades and Eastern Cascades, Slopes, and
Foothills ecoregions to the east. The mild Mediterranean climate of the
ecoregion is characterized by hot dry summers and wet winters; the amount of
winter moisture varies, however, within the ecoregion decreasing from west to
east. The Klamath-Siskiyou region is widely recognized as an important biodiversity
hotspot (Whittaker, 1960; Kruckeberg, 1984; Wagner, 1997; DellaSala and others,
1999) containing more than 3,500 plant species, more than 200 of which are
endemic (Sawyer, 2007). A biological assessment by DellaSala and others (1999)
ranked the Klamath-Siskiyou region as the fifth richest coniferous forest in
terms of species diversity and the International Union for the Conservation of
Nature considers the region one of notable botanical importance (Wagner, 1997).
Twenty-nine different species of conifers can be found in the Klamath (Sawyer,
1996).
This
ecoregion is underlain by belts of Paleozoic to Mesozoic metasedimentary and
metavolcanic rocks separated by linear belts of serpentinite. Most of these
belts are intruded by Mesozoic granitic rocks and/or overlain by late Mesozoic
sedimentary rocks. All of these rocks are overlain by gravel and alluvial
deposits of Cenozoic age (Potter, 1966, Snoke and Barnes, 2006). Soils
developed on serpentine are toxic and nutrient poor, and are characterized by high
levels of magnesium, nickel, and chromium as well as low levels of calcium.
Seventy endemic species of plants are associated only with serpentine
extrusions in the Siskiyou Mountains, outnumbering those associated with any
other serpentine outcrop in North America (Coleman and Kruckeberg, 1999;
Sawyer, 2007).
Forests
account for approximately three-quarters of the ecoregion’s areas, and are
generally organized along elevation and longitudinal gradients, while
grasslands and shrubs account for approximately 15 percent of the ecoregion
area (Homer and others, 2007). Redwood forests dominate the coastal portions of
the ecoregion giving way to Douglas-fir, tanoak, madrone, and canyon live oak
further inland followed by Douglas-fir and Ponderosa pine in the eastern
portions of the ecoregion (Sawyer, 1996). White fir and Shasta fir can be found
at higher elevations and Mountain hemlock is common at subalpine elevations
(Sawyer, 1996). Oak woodlands are common in foothills of the Eel, Trinity, and Sacramento watersheds.
Agriculture
and developed landscapes comprise much of the remainder of the ecoregion. The
major land uses within the ecoregion include forestry, farming, grazing,
tourism, and mining. Approximately 83 percent of the ecoregion is managed by
the federal government, most of which is for public use (fig. 2). The Forest
Service manages 12 wilderness areas and 8 national forests, accounting for the
majority of public lands in the ecoregion. Other federal land holders include
Bureau of Land Management, National Park Service, and the Bureau of
Reclamation. There are also several Indian reservations located across the
ecoregion. Protected lands (CBI, 2003) that limit permanent anthropogenic
conversion and are managed for natural ecosystem values
2 comprise 17.3 percent of the ecoregion.
Farming
is limited and generally confined to the larger alluvial valleys. One of the
more productive agricultural locations in the ecoregion exists in a corridor
between Ashland, Medford, and Grants Pass, Oregon. Developed land uses are
sparse. Medford and Grants Pass in Oregon are the two largest urban areas with
respective 2005 population estimates of 70,147 and 28,882 (U.S. Census Bureau,
2008). Other urban areas include Roseburg and Ashland in Oregon, and Willits
and Yreka in California.
Contemporary Land Cover Change (1973 to 2000)
The overall
spatial change (i.e. the amount of area that changed at least one time) between
1973 and 2000 was 10.3 percent (4,929 km2) (table 1). Compared to
other western ecoregions, the Klamath experienced a modest amount of change
although the rate was substantially lower than other forested ecoregions in the
Pacific Northwest (fig. 3). Of the 10.3 percent of the ecoregion that did
change, 3.2 percent of the ecoregion experienced change in more than one time
interval, indicating a cyclic pattern consistent with the changes associated
with forestry. Change within the four individual temporal periods ranged from a
low of 3.0 percent between 1980 and 1986 to a high of 4.2 percent in the 1986
to 1992 and 1992 to 2000 intervals (table 2). When the temporal intervals are
normalized to an average annual rate to compensate for the uneven lengths
between image classifications, the 1986 to 1992 period experienced the highest
rate of change at 0.7 percent per year (fig. 4). The other three intervals were
fairly stable at approximately 0.5 percent per year (table 2). Staus and others
(2002) found similar rates of forest disturbance between 1972 and 1992 in the
Klamath-Siskiyou region. Land cover change in the Klamath was substantially
lower than that of the adjacent Coast Range ecoregion (Sohl, in press). In
part, this is explained by the large percentage of public lands and areas of
high protection that either minimize, or restrict, timber harvest. Table 3
provides estimates of net forest change, public land ownership, and protected
lands for forested-dominated western ecoregions. In the Pacific Northwest, with
the exception of the Cascades ecoregion, the Klamath had the lowest net loss of
forest cover over the 27-year study period (594 km2) (table 3 and 4)
and ranked behind only the Sierra Nevada Mountains Ecoregion in terms of the
proportion of public lands found within the ecoregion.
Forests
covered an estimated 76.6 percent of the ecoregion in 1973 and declined to 75.3
percent by 2000, a loss of 1.2 percent and approximately 593 km2.
The only interval to experience a net increase in forest was between 1980 and
1986 with an increase of 0.2 percent (fig. 6). Grassland/shrubland, which
accounted for an estimated 14.3 percent of the ecoregion in 1973, increased to
15.5 percent in 2000, a net increase of 1.3 percent over 27 years. Furthermore,
we estimate that between 1973 and 1980 re-growth of forests, often captured as
grassland/shrublands in the earliest stages of regeneration, outpaced logging
by approximately 74 km2 per year. Logging accelerated in the 1980s
and early 1990s (Daniels, 2005) resulting in a deficit of 43 km2 per
year between 1986 and 1992. The 1990s saw a shift back to trends witnessed
during the 1970s where re-growth outpaced cutting at a rate of approximately 26
km2 per year. These trends are consistent with findings from Cohen
and others (2002) that investigated forest disturbance in western Oregon. Class changes over the five dates and four temporal periods can be found in Table
4.
Agriculture
was the third most common land cover in the Klamath and was generally confined
to the eastern and northern portions of the ecoregion. Farmland remained stable
throughout the study period at approximately 4.5 percent of the ecoregion.
Changes
associated with new development were relatively small in the Klamath Mountains. We estimate that developed land-cover increased by 0.4 percent over the
entire 27-year study, an increase of approximately 190 km2. Developed
lands were estimated to account for 1.8 percent of the ecoregion in 1973,
increasing to 2.2 percent by 2000. New development could be found located
around existing cities such as Roseburg, and along the Interstate 5 corridor
between Grants Pass and Medford. The only major urban areas in California were Yreka, Weaverville, and Willits.
As
expected, the leading land cover conversions were associated with timber
harvesting (table 5). Changes associated with logging accounted for a majority
of change in each temporal period, ranging from a high of nearly 95 percent
between 1973 and 1980 to 72 percent between 1992 and 2000. Changes between
forest, mechanical disturbance, and grassland/shrubland are closely linked and
when combined represent the cyclical nature of logging. During the last two
intervals fire (classified as nonmechanical disturbance) took on a larger role
as an agent for land change, accounting for an estimated 189 km2
between 1986 and 1992 and 206 km2 between 1992 and 2000 (table 5).
Drivers
of land cover change in the Klamath Mountains Ecoregion were numerous and
diverse. Forest management policy was driving much of the change associated
with logging, however, in later years, environmental policy has taken on
increasing importance. The collapse of the Asian export market, listing of the
northern spotted owl on the Endangered Species List in 1990, and the Northwest
Forest Plan of 1994 are likely drivers of land cover change in the region with
the most direct result being a decrease of timber production to approximately
25 percent of 1980s levels (Daniels, 2005). Changes in global market demand for
Pacific Northwest timber are also significant and were best characterized by
the Asian economic recession of the 1990s that resulted in a substantial
decrease in demand for regional timber products. Decades of fire suppression
and climate change have likely contributed to the more recent emergence of fire
as a major land-cover conversion typified by more frequent high-intensity stand
replacing burns in Northern California (Westerling and others, 2006).
References Cited
CBI (Conservation Biology
Institute), 2003, Conservation Biology Institute protected areas GIS data
layer, Conservation Biology Institute, Corvallis, Oregon. Available from http:consbio.org
(last accessed September, 2008)
Cohen, W. B., T. A. Spies,
R. J. Alig, D. R. Oetter, T. K. Maiersperger, and M. Fiorella, 2002,
Characterizing 23 years (1972-95) of stand replacement disturbance in Western
Oregon forests with Landsat imagery, Ecosystems, Vol. 5, pp. 122-137
Coleman, R. G., and A. R.
Kruckeberg, 1999, Geology and plant life of the Klamath-Siskiyou Mountain
region, Natural Areas Journal, Vol. 19, No. 4, pp. 320-340
Daniels, J. M., 2005, The
rise and fall of the Pacific Northwest log export market, United States
Department of Agriculture, Forest Service, General Technical Report
PNW-GTR-624.
DellaSala, D. A., S. B.
Reid, T. J. Frest, J. R. Strittholt, and D. M. Olson, 1999, A global
perspective on the biodiversity of the Klamath-Siskiyou ecoregion, Natural
Areas Journal, Vol. 19, No. 4, pp. 300-319.
DellaSala, D. A., N. L.
Staus, J. R. Strittholt, A. Hackman, and A. Iacobelli, 2001, An updated
protected areas database for the United States and Canada, Natural Areas
Journal, Vol. 21, No. 2, pp. 124-135.
Homer, C., J. Dewitz, J.
Fry, M. Coan, N. Hossain, C. Larson, N. Herold, A. McKerrow, J. N. VanDriel and
J. Wickham. 2007. Completion of the 2001 National Land Cover Database for the
Conterminous United States, Photogrammetric Engineering and Remote Sensing,
Vol. 73, No. 4, pp 337-341.
Kruckeberg, A. R., 1984, California Serpentines: Flora, Vegetation, Geology, Soils and Management Problems,
University of California Press, Berkeley, California, USA.
Potter, Irwin, 1966, Geology
of the Klamath Mountains province: in Bailey, E.H. (ed.), Geology of
Northern California: California Division Mines and Geology Bulletin 190, p.
19-39.
Sawyer, J. O., 1996, Northern
California, In: Kirk, R. (ed.), The Enduring Forests: Northern California, Oregon,
Washington, British Columbia and Southwest Alaska, The Mountaineers Press,
Seattle, Washington, pp. 22-41.
Sawyer, J. O., 2007, Why are
the Klamath Mountains and adjacent north coast floristically diverse? Fremontia,
Vol. 35, No. 3, pp. 3-11
Scott, J. M., F. Davis, B.
Csuti, R. Noss, B. Butterfield, S. Caicco, G. Groves, J. Ulliman, H. Anderson,
and R. G. Wright, 1993, Gap analysis: a geographic approach to protection of
biological diversity, Wildlife Monographs, Vol. 123, pp. 1-41
Snoke, A.W., and Barnes,
C.G. (eds.), 2006, Geological studies in the Klamath Mountains province, California and Oregon: Geological Society of America Special Paper 410, 505 p.
Sohl, T., 2008, Contemporary
land cover change in the Coast Range Ecoregion, in Acevedo, W. eds., Status and
Trends of Western United States Land Cover, U.S. Geological Survey Professional
Paper, in press.
Staus, N. L., J. R.
Strittholt, D. A. DellaSala, and R. Robinson, 2002, Rate and pattern of forest
disturbance in the Klamath-Siskiyou ecoregion, USA between 1972 and 1992, Landscape
Ecology, Vol. 17, pp. 455-470.
Wagner, D. H., 1997,
Klamath-Siskiyou region, California and Oregon, USA, In: Davis, S. D., V. H.
Heywood, O. Herrera-MacBryde, J. Villa-Lobos, and A. C. Hamilton (eds), Centres
of Plant Diversity, the Americas, Vol. 3, World Wildlife Fund for Nature and
IUCN (World Conservation Union), New York, New York, USA, pp. 74-76.
Westerling, A. L., H. G.
Hidalgo, D. R. Cayan, and T. W. Swetnam, 2006, Warming and Earlier spring
increase Western U.S. forest wildfire activity, Science, Vol. 313, pp.
940-943
Whittaker, R. H., 1960,
Vegetation of the Siskiyou Mountains, Oregon and California, Ecological
Monographs, Vol. 30, pp. 279-338
U.S. Census Bureau, Administrative and Customer Services
Division,
Statistical Compendia Branch, Last Revised: February 28, 2008 at 08:40:14 AM.
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Table 1.
Percentage of the ecoregion that experienced change and associated error
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[Most of
the sample pixels remained unchanged (xx.x percent), whereas x.x percent
changed at least once through the study period]
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Number
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Percent
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Margin
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Lower
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Upper
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Standard
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Relative
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of
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of
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of error
|
bound
|
bound
|
error
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error
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|
changes
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ecoregion
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(+/- %)
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(%)
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(%)
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(%)
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(%)
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1
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7.1
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1.9
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5.2
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9.0
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1.3
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18.3
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2
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2.8
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0.8
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2.0
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3.6
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0.6
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19.9
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3
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0.4
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0.2
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0.3
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0.6
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0.1
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26.4
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4
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0.0
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0.0
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0.0
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0.1
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0.0
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34.9
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Overall spatial change
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10.3
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2.3
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8.0
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12.6
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1.5
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15.0
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Table 2.
Raw estimates of percent change in the ecoregion computed for each of the
four time periods and associated error at an 85-percent confidence level
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[Estimates
of change per period normalized to an annual rate of change for each of the
four time periods]
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Period
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Total change
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Margin of error
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Lower bound
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Upper bound
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Standard error
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Relative error
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Average rate
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(% of ecoregion)
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(+/- %)
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(%)
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(%)
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(%)
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(%)
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(% per year)
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1973-1980
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3.3
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1.1
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2.1
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4.4
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0.8
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23.2
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0.5
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1980-1986
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3.0
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1.0
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2.1
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4.0
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0.6
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21.4
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0.5
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1986-1992
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4.2
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1.2
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3.0
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5.4
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0.8
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19.9
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0.7
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1992-2000
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4.2
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1.3
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2.9
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5.5
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0.9
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21.1
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0.5
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Period
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Total change
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Margin of error
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Lower bound
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Upper bound
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Standard error
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Relative error
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Average rate
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(km2 of ecoregion)
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(+/- km2)
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(km2)
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(km2)
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(km2)
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(%)
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(km2 per year)
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1973-1980
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1554
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533
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1022
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2087
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361
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23.2
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222
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1980-1986
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1449
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457
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992
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1906
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|
310
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21.4
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|
242
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1986-1992
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2011
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|
592
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1419
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2603
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|
401
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19.9
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335
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1992-2000
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2017
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|
627
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1390
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2644
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|
425
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21.1
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252
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Table
3.Comparison of forest change, public lands, and protected lands in western
forested ecoregions.
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Forest change
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Protected area
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Public Ownership
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Ecoregion
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Ecoregion area (km2)
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Percent forest (2000)
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(km2)
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%
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(km2)
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% ecoregion
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(km2)
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% ecoregion
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% High Protection
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Coast Range
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53986
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72.4
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-2051
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-5.2
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6531
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12.1
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13359
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24.7
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48.9
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Puget
Lowlands
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16454
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48.4
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-1662
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-20.8
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83
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0.5
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567
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3.4
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14.6
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Willamette Valley
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14883
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33.5
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-625
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-12.5
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156
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1.0
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561
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3.8
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27.8
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Cascades
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46416
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82.3
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232
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0.6
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13500
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29.1
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30952
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66.7
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43.6
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Sierra
Nevada
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52872
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70.1
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-1851
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-4.9
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15143
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28.6
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42166
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79.8
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35.9
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Klamath Mtns.
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48537
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75.3
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-594
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-1.6
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8393
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17.3
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34678
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71.4
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24.2
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[1]
U.S. Geological Survey, Western Geographic Science Center, Menlo Park, CA 94025
[2]
GAP protection code 1 or 2 (Scott and others, 1993; DellaSala and others, 2001)
U.S. Department of the Interior |
U.S. Geological Survey
