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Climate Change Refugia for Biodiversity in the Klamath-Siskiyou Ecoregion
Author(s) :David Olson, Dominick A. DellaSala, Reed F. Noss, James R. Strittholt, Jamie Kass, Marni E.
Koopman and Thomas F. Allnutt
Source: Natural Areas Journal, 32(1):65-74. 2012.
Published By: Natural Areas Association
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Volume 32 (1), 2012 Natural Areas Journal 65
Natural Areas Journal 32:65–74
Biodiversity in the
1 Conservation Earth Consulting
4234 McFarlane Ave.
Burbank, CA 91505
Dominick A. DellaSala2,6
Reed F. Noss3
James R. Strittholt4
Marni E. Koopman2
Thomas F. Allnutt5
2 Geos Institute
84 Fourth Street
Ashland, OR 97520
3 Department of Biology
University of Central Florida
4000 Central Florida Blvd.
Orlando, FL 32816-2368
4 Conservation Biology Institute
260 SW Madison Avenue, Suite 106
Corvallis, OR 97333
5 Department of Environmental Science,
Policy and Management
130 Mulford Hall
University of California
Berkeley, CA 94720-3114
6 Corresponding author:
ABSTRACT: The Klamath-Siskiyou Ecoregion has been a refuge for species during past climate change
events, but current anthropogenic stressors are likely compromising its effectiveness as a refugium for this
century’s projected changes. Reducing non-climate stressors and securing protection for large, complex
landscapes are important long-term actions to alleviate climate change impacts on biodiversity. Equally
important is the immediate protection of a network of climate change microrefugia, particularly old
growth and intact forests on north-facing slopes and in canyon bottoms, lower- and middle-elevations,
wetter coastal mountains, and along elevational gradients. Such areas provide local opportunities for
vulnerable species to persist within the ecoregion. We identify a provisional set of 22 highest-priority and
40 high-priority microrefugia that occur mostly outside of existing protected areas and along wetter and
lower elevations of the ecoregion. Proposed reserve designs, if fully implemented, would capture most of
the recommended microrefugia, although we found 11 important gaps. Most of the region’s biodiversity,
endemic species, and species vulnerable to climate change are invertebrates, non-vascular plants, and
fungi that are largely restricted to persistently cool and moist late-successional forests. Opportunities for
climate change response for vulnerable taxa will necessarily be local due to a limited capacity of many
species to move to new habitat, even over relatively small distances where land use practices create
inhospitable conditions. The ecoregion’s distinctive and endemic serpentine-substrate ﬂora also is at risk
and possible refugia are sites that will retain wet soil conditions, such as seeps and bogs.
Index terms: climate change, ecoregion, Klamath-Siskiyou, microrefugia, refugia
The Klamath-Siskyou Ecoregion (KSE)
contains globally important biodiver-
sity–only five other temperate forests
regions are as diverse or home to as many
endemic species and ancient lineages (e.g.,
Caucasus, Southwestern China, Southeast-
ern United States, Coastal Plain/Southern
Appalachians, Valdivia rainforests of Chile
and Argentina; Olson et al. 2001; Tecklin
et al. 2011). The special location (latitude
and coastal proximity), rugged terrain, cli-
matic stability, and complexity of soils and
microclimates have allowed the region to
act as a refuge from past climatic changes
for species and natural communities requir-
ing cool and moist conditions (Whittaker
1960, 1961; Stebbins and Major 1965;
Wagner 1997; Coleman and Kruckeberg
1999; Sawyer 2007).
One might expect that the KSE will con-
tinue to function well as a climate change
refugium as human-caused climate change
progresses. However, cumulative land use
impacts combined with projected climate
change could have a profound impact on
the ecoregion’s species and ecosystems.
In the KSE, over a century of land use
activities (e.g., logging, mining, livestock
grazing, damming of rivers, mining, and
human-caused alterations of ﬁre) have
resulted in loss or degradation of mesic
habitats (DellaSala et al. 1999) that may
have previously functioned as refugia over
millennia. Impacts include loss of contigu-
ous habitat along intact elevational and
other environmental gradients that may
facilitate climate-related shifts in natural
communities and loss and degradation of
most of the mature and old-growth for-
ests (e.g., only about 28% of the historic
old-growth forests remain; Strittholt et
al. 2006), particularly mesic lowland and
mid-elevation habitats (Staus et al. 2002).
Increasing prevalence of invasive plants
and pathogens facilitated by road building
and land use practices poses an additional
threat to native species and communities
(DellaSala et al. 1999).
The existing protected area system (i.e.,
National and State Parks, Wilderness Areas,
National Monuments, Botanical Areas) is
inadequate for ensuring the persistence
of most of the ecoregion’s vulnerable
biodiversity (DellaSala et al. 1999; Noss
et al. 1999; Carroll et al. 2010). Existing
reserves largely protect higher-elevation
communities, while the lower-elevation
reserves are limited in their geographic
extent, thereby missing many distinct
lowland species assemblages and areas
that may act as potential microrefugia.
We deﬁne microrefugia as sites with cool
and moist conditions conducive to the
persistence of species vulnerable to climate
change. Thus, our conservation strategy for
the KSE builds on prior reserve propos-
als (Noss et al. 1999; Carroll et al. 2010;
KS Wild 2010; Siskiyou Project 2010) by
C O N S E R V A T I O N I S S U E S
66 Natural Areas Journal Volume 32 (1), 2012
adding microrefugia and other elements
to create a reserve design more robust to
anticipated increases in temperature and
changes in precipitation over the century
(Koopman et al. 2009).
CORE CONSERVATION ELEMENTS
FOR ROBUST RESERVE DESIGN IN A
Fundamental to the development of a robust
conservation design are three core-plan-
ning elements: (1) reduction of non-cli-
mate stressors; (2) protection of complex
landscapes; and (3) protection of climate
change microrefugia. Taken together, they
are the foundation for guiding reserve
design and conservation implementation
in the KSE.
Reduction of Non-Climate Stressors
Reducing non-climate stressors across the
landscape, such as curtailing or greatly
reducing logging and road building, is
the single most important action that land
managers can take to help the regional
biota and ecosystems persist in the face
of a changing climate. The release from
stressors should be strategically targeted to
critical core habitats, old-growth forest mi-
crorefugia, and adaptation corridors along
environmental gradients (sensu, Olson et
al. 2009). For example, if large complex
landscapes were off-limits to logging
(only about 13% of the region is strictly
protected; DellaSala et al. 1999), and all
of the predicted local climate refugia,
old-growth forests, and priority corridors
in the KSE (e.g., Noss et al. 1999) were
effectively protected, this would have a
much more positive effect for biodiversity
than if most of the area released from log-
ging was in highly degraded, mid-elevation
production forests. The release of strategic
areas from land use stressors would need
to allow maturing forests to once again
dominate the landscape.
Protection of Complex Landscapes
Securing a high level of protection and
undertaking ecologically based restoration
in degraded areas is important, as well as
protection of large, complex landscapes
with diverse terrains, soils, microclimates
and other environmental gradients. In
particular, low and mid-elevation habitats
in higher precipitation areas (e.g., along
the coast) will provide multiple local op-
portunities for persistence of vulnerable
species. In the KSE, conservation groups
have identiﬁed two areas having these
characteristics: a 243,000 ha land bridge
known as the proposed Siskiyou Crest
National Monument (considered a climate
refuge) in southwest Oregon and northern
California (KS Wild 2010) and a ~445,000
ha proposed Siskiyou Wild Rivers National
Salmon and Botanical Area in southwest
Oregon, a hotspot of serpentine ﬂora and
wild rivers (Siskiyou Project 2010; Figure
1). Protection of these areas will greatly im-
prove the chances for persistence of a large
portion of the ecoregion’s terrestrial and
freshwater biota even if we are uncertain
of the magnitude, timing, and distribution
of changes in temperature and precipitation
at sub-ecoregional scales (e.g., Murphy et
al. 2004; Moilanen et al. 2006).
Figure 1. Climate change vulnerability zones (coastal, transition, dry, high elevation) of the Klamath-
Siskiyou Ecoregion, southwest Oregon and northern California, used in the analysis to inform priority
site selection for conservation action.
Volume 32 (1), 2012 Natural Areas Journal 67
Protection of Climate Change
In order to maintain pockets of habitat
for climate-vulnerable species, conserva-
tion attention should be aimed at securing
microrefugia that may uniquely provide
opportunities for many species to persist
and are particularly threatened due to ongo-
ing habitat degradation and rapid warming.
The importance of microrefugia for the
long-term persistence of species that are
sensitive to climate change is increasingly
being recognized (Noss 2001; Loarie et
al. 2008, 2009; Rull 2009, 2010; Ashcroft
2010; Dobrowski et al. 2010). In temper-
ate regions, terrain positions and habitat
types that maintain persistent cool and
moist conditions favorable for effective
microrefugia are increasingly well deﬁned
(e.g., Dobrowski et al. 2010).
Because of the rapid speed of climate
change (Loarie et al. 2008, 2009), includ-
ing warmer temperatures (Koopman et al.
2009) and diminishment of fog (Johnstone
and Dawson 2010) in the KSE, opportu-
nities for long-term persistence for many
species will be local, likely within a scale
of a few kilometers, from the location of
present populations. Many species will be
unable to shift rapidly enough to areas with
more favorable conditions. Moreover, most
of KSE’s species, distinctive (endemic)
species, and those vulnerable to climate
change are mesophilic, old-growth forest
specialists, largely lesser known taxa (by
the public) such as invertebrates, fungi,
bryophytes, and other non-vascular plants
(Olson 1992; Lattin 1993; Olson 2010;
Vicente 2010). The majority of these taxa
cannot cross even small distances of terrain
with unfavorable conditions (e.g., light,
hot, and dry; Frest and Johannes 1993;
Niwa and Peck 2002). Thus, protection
and restoration of microrefugia around
extant populations is essential for the long-
term perpetuation of the vast majority of
the KSE biota. The ecoregion’s endemic
serpentine ﬂora (Kruckeberg 1984; Har-
rison et al. 2006; Sawyer 2007) is also
highly vulnerable to projected increases
in temperature and drying (Damschen et
al. 2010) and some taxa may only persist
within persistently wet pockets and seeps
surrounded by late-seral forests (collec-
tively mature and old growth) that can act
as climatic buffers.
Many extant microrefugia and the species
and populations they contain may be lost
or degraded within a few decades due to
ongoing exploitation of forests and land-
scapes within the ecoregion, particularly
at low and mid elevations, slow pace of
change that is typical for forest manage-
ment and protected areas practices, and
rapid changes being documented in climate
and natural communities (Damschen et al.
2010). Although the long-term efﬁcacy of
microrefugia is still uncertain (Carroll et al.
2010; Dobrowski et al. 2010), especially
if they remain embedded within largely
degraded landscapes, it remains a prudent,
bet-hedging strategy in the face of uncer-
tainty to protect a network of microrefugia
representative of the ecoregion’s distinct
Microrefugia Site Features
Site features for effective microrefugia in
the KSE include north-facing slopes, valley
bottoms and steep canyons, and sinks and
basins because they are shadier and exist
where cool air predictably pools in the
lower sites (Dobrowski et al. 2010). Such
sites are likely to have climate states and
trends that are decoupled from regional
averages, a requisite for microrefugia to
persist through time. Forests with a north-
east- and north-facing aspect also have a
lower frequency of wildﬁres that can alter
the capacity of habitats to retain cool and
moist conditions (Taylor and Skinner 2003;
Alexander et al. 2006).
Habitat types that will function well as
microrefugia for climate change-sensitive
species include late-seral forests, although
the greater litter, understory vegetation,
and canopy complexity and biomass of
old-growth forests (> 150 yrs) makes them
superior at retaining moisture (Chen et al.
1999). Late-seral forests that occur in areas
with high-precipitation and fog, such as
in coastal mountains (Loarie et al. 2008;
Ackerly et al. 2010; Carroll et al. 2010)
or other areas that experience signiﬁcant
orographic precipitation (e.g., > 1143 mm
annual precipitation) will, on average, be
better able to retain more moisture and
cooler conditions than lower precipita-
tion zones. This is due to more abundant
water and greater canopy, understory
vegetation, litter biomass, and complexity
in these forests. Late-seral forests within
watersheds are also superior to degraded,
logged, roaded, and burned vegetation for
providing cooler stream temperatures and
robust aquatic ecosystems (Strittholt and
DellaSala 2001; Staus et al. 2010).
Storm tracks, regional rainfall, and fog pat-
terns may shift due to climate change (Det-
tinger et al. 1998; Salathé et al. 2008; Mote
and Salathé 2009; Johnstone and Dawson
2010), but coastal mountains are expected
to continue to receive Paciﬁc storms ﬁrst
and much of the region’s rainfall into the
future (Daly et al. 1994). Certainly, vul-
nerable species and communities occur at
higher elevations and in drier areas towards
the eastern portion of the ecoregion, but the
vast majority of distinctive biodiversity for
the ecoregion (all taxa being considered)
occur within the coastal fog and transition
zones (Figure 1; Sawyer 2007). The latter
zone includes more mesic forests along
the Siskiyou Crest (Oregon/California),
Eddy Mountains (northwest California),
Scott Mountains (northwest California),
and Yolla Bolly’s (southern limits of the
ecoregion) that are relatively far from
the coast. In general, the larger and more
round a forest block, the greater the core
habitat area–internal habitat that does not
experience the drying effects of forest edges
(Chen et al. 1999).
Natural communities and vulnerable spe-
cies within refugia also willhave improved
opportunities for persistence if microrefu-
gia span broad elevational gradients, allow-
ing populations to shift locally over time
through contiguous mesic habitat (Noss
2001; Olson et al. 2009). North-South cor-
ridors of contiguous natural vegetation are
important for many reasons, such as dis-
persing vertebrates, but a swiftly changing
climate will likely limit the ability of most
slowly dispersing organisms to move long
distances northwards over generations.
REPRESENTATION OF BIODIVERSITY
68 Natural Areas Journal Volume 32 (1), 2012
MESOREFUGIA AS A PROXY
Until patterns of local endemism and
beta-diversity for speciose groups, such
as invertebrates, are better known, prox-
ies for mapping distinct assemblages can
be used to assess how well a network of
microrefugia provides refuge to KSE’s
diverse biota. Useful proxies for assess-
ing representation of biodiversity within
and among microrefugia are mesorefugia.
We deﬁne mesorefugia as large areas that
contain nested clusters of microrefugia
with similar species assemblages that have
functioned as a refugium over millennia
(Rull  deﬁnes mesorefugia as larger
regions to which temperate biotas shifted
during glacial maxima). Mesorefugia
typically occur at the scale of mountain
ranges or watershed complexes along
coastlines, and their location along river
canyons (e.g., Rogue, Umpqua, Klamath,
Eel rivers) may facilitate future expansions
and enable vagile species to move more
freely across landscapes. Careful selection
and protection of microrefugia of varying
species assemblages (e.g., plant association
groups) within and among mesorefugia
would help to achieve representation goals
while maximizing the number of extant
species that will persist in emerging novel
Mesorefugia analyses complement exist-
ing representation analyses that focus on
vegetation types and other communities
derived from combinations of biophysi-
cal features (e.g., Vance-Borland 1999;
Staus et al. 2001; Carroll et al. 2010). As
such, candidate mesorefugia (Figure 2)
for the KSE were initially identiﬁed from
large-scale biophysical features and loca-
tions that predict effective refugia–coastal
mountains with complex topography and
areas of high precipitation (Loarie et al.
2009; Rull 2009, 2010; Dobrowski 2010).
Areas with concentrations of restricted-
range (i.e., local endemic) species or relict
taxa dependent on cool and moist habitats
were also evaluated to reﬁne candidate
mesorefugia locations and boundaries
(i.e., where multiple species boundaries
overlap). These include the distribution of
Brewer spruce (Picea breweriana), Engel-
mann spruce (Picea engelmanni), foxtail
pine (Pinus balfouriana) (Sawyer 2007),
Plethodon and Dicamptodon salamander
species and subgoups (Bury 1973; Mead
et al. 2005; Steele and Storfer 2006), and
numerous other plants (Sawyer 2007) and
invertebrates (Olson 1992), such as harvest-
man (Briggs 1969, 1971ab), millipedes
(Gardner and Shelley 1989; Olson 1992),
trapdoor spiders (Cokendolopher et al.
2005), and land snails (Frest and Johannes
1993). We stress the mesorefugia proposed
here are provisional and will beneﬁt from
more rigorous analyses of biophysical
predictors and species distributions.
Based on these criteria and species distribu-
tion maps, important mesorefugia for the
Figure 2. Provisional mesorefugia (ovals) within the Klamath-Siskiyou Ecoregion, southwest Oregon
and northern California, approximated from large-scale predictors (e.g., coastal mountains in areas of
relatively high precipitation) and an overlay of the distribution of mesophilic, restricted-range species
including Plethodontid and Dicamptodon salamanders, Caseyid millipedes, Pentanychid harvestman,
endemism zones for vascular plants, and relict conifers. Mesorefugia likely contain concentrations of
restricted-range species due to their persistently wet conditions and long-term stability. Dashed ovals
represent high-elevation refugia that may, or may not (depending on the severity of warming tem -
peratures at higher elevations), function well under current and future human-caused climate change.
Numbering refers to locations discussed in the text.
Volume 32 (1), 2012 Natural Areas Journal 69
KSE include: (1) Kalmiopsis; (2) North
Siskiyou Mountains; (3) East Siskiyous; (4)
north of the southern bend of the Klamath
River; (5) West Siskiyous; (6) Lower Scott
Bar River; (7) Russian Wilderness; (8)
Lower Trinity River (multiple locations);
and (9) Middle Eel/Yolla Bolly (multiple
locations, numbers correspond to Figure
2). The Russian Wilderness was selected
due to the extraordinary sympatric assem-
blage of conifer species whose presence
could be due to mesorefugia conditions.
The mesorefugia located in the coastal
zone experiences the highest rainfall in
the KSE and is likely to have the highest
concentrations of restricted-range and cli-
mate change-vulnerable species (contrast
Figures 1 and 2). We acknowledge that
much KSE biodiversity occurs outside
of these mesorefugia, but suggest that
ensuring adequate protection of habitats
buffered from warming in these zones is
an important ﬁrst step.
The current protected areas system does
a poor job of representing the provisional
mesorefugia. Only the Kalmiopsis, Sis-
kiyou, Russian, and Middle Eel/Yolla
Bolly Wilderness areas and redwood parks
encompass portions of likely mesorefu-
gia. In general, Wilderness areas largely
protect higher elevations, not the middle
and lower slopes where most of the mi-
crorefugia are likely to occur. Proposed
expanded reserve networks would repre-
sent all of the provisional mesorefugia, if
implemented, including those at lower and
middle elevations (e.g., contrast Figures
2 vs. 3b). We also propose three priority
mesorefugia corridors to link: (1) Siskiyou
Crest–Kalmiopsis, (2) Kalmiopsis–Sis-
kiyou Mountains, and (3) Trinity/Scott Bar
River–Siskiyou Crest (numbers correspond
to Figure 3a).
We used our microrefugia site features to
identify a set of provisional areas outside
extant protected areas that warrant im-
mediate conservation attention. For the
portion of the ecoregion outside of for-
mal protected areas, 22 highest-priority
microrefugia and 40 high-priority areas
containing late-seral forest and other key
habitat types (e.g., serpentine barrens)
were identiﬁed as candidate microrefugia
(Figure 3a). Many important old-growth
forest microrefugia occur in close prox-
imity to existing protected areas, such
as the Kalmiopsis Wilderness. Most of
the candidate microrefugia lie towards
the western, wetter part of the ecoregion
and are generally located at mid and low
elevations. Remnants of late-seral forest in
the fog zone are particularly important to
protect and restore, as they likely contain
a sizable proportion of vulnerable species.
Some old-growth forest blocks at higher
elevation in the eastern part of the ecore-
gion were also recommended, as they span
a broad elevational range and are among
the largest remaining old-growth fragments
in the ecoregion. Data on late-seral forests
were unavailable for some portions of the
ecoregion, such as the southwestern coastal
hills and the foothills of the Central Valley
that may contain additional microrefugia
Finer-resolution analyses and ﬁeld sur-
veys within priority areas (Figure 3a) are
required to identify the particular blocks
of old-growth forest and bottomland sites
that have the highest potential to act as
microrefugia. The nature of the landscape
and the mosaic of late-seral forests can have
a major inﬂuence on the efﬁcacy of mi-
crorefugia. For example, even a relatively
small old-growth forest fragment situated
in a steep, north-facing canyon that experi-
ences shade most of the time will likely
function well as a long-term refuge for
In sum, several microrefugia deserve
immediate conservation attention, includ-
ing: southern bend of the Klamath River,
California; lower slopes of the Klamath
River from around China Point eastwards
to Hamburg, California; northern slope
of the Scott Bar Mountains and along the
lower Scott River in California; old-growth
fragments close to the coast in Oregon
and in the foothills behind the redwood
belt in northwestern California; north-
facing slopes of the Middle Smith River,
California; larger old-growth pockets to
the west of the Kalomiopsis Wilderness,
southwest Oregon; southeastern watersheds
of the Siskiyou Mountains (e.g., Dillon
and Rock Creek area, California); northern
Siskiyou Mountains to western Siskiyou
Crest region, California; and a network
of serpentine-substrate areas representing
assemblages of endemic plant species and
their surrounding forest buffers mainly in
This provisional network of priority
climate change microrefugia outside the
existing reserve system should be targeted
for immediate protection and restoration.
A variety of conservation approaches is
required because candidate sites are in
diverse locations, habitat types, tenures,
and land use pressures. Some are located
within active federal and state forestry
zones, and some are on private lands. The
priority areas identiﬁed here would not, by
themselves, constitute a comprehensive
conservation strategy as they are intended
primarily to buffer a good portion of the
KSE biota from extinction and extirpation
due to changing climate, and they would not
necessarily address a wide range of other
conservation goals and objectives.
MICROREFUGIA AND PROTECTED
Representation and Existing
We also intersected remaining late-seral
forests with north-facing slopes (N, NE,
NW, Figure 3ab) and areas of relatively
high precipitation with microrefugia char-
acteristics (see Appendix for methods). Us-
ing ecoregion-scale data on forest cover and
topography, it was challenging to identify
the small river valleys and bottomlands that
consistently pool cooler air and may func-
tion as additional microrefugia. More local-
scale data and on-the-ground surveys are
required to identify potential bottomland
refugia. For similar reasons, we also did not
attempt to identify potential microrefugia
for the vulnerable serpentine ﬂora.
Based on this analysis, the current protected
area network under-represents most of the
important microrefugia for the KSE (Figure
3a). For instance, only 16% of remaining
old-growth forest occurs within strictly
protected areas (Table 1). Some important
70 Natural Areas Journal Volume 32 (1), 2012
Figure 3. (A) Provisional microrefugia (highest priority and priority) and proposed mesorefugia corridors outside (numbers refer to locations described in the text) of formal protected areas in
the Klamath-Siskiyou Ecoregion, southwest Oregon and northern California. High-quality microrefugia inside formal protected areas are not identiﬁed. The mature forest shown is north-fac-
ing only. Circles were drawn based on visual inspection of the mapped old forest polygons. (B) Some priority microrefugia in the Klamath-Siskiyou Ecoregion, southwest Oregon and northern
California, which are not encompassed in the proposed expanded reserve network (Noss et al. 1999). Black ovals are highest priority and white ovals are high priority gaps in protected areas
coverages. Circles were drawn by visual inspection of old-growth forest concentrations.
Volume 32 (1), 2012 Natural Areas Journal 71
blocks of lower- and middle-elevation
old-growth microrefugia occur in existing
reserves – such as in the coastal redwood
parks, Kalmiopsis, Siskiyou, Wild Rogue,
and Russian Wilderness areas, and Oregon
Caves National Monument – but many
are located outside these areas. While the
extant reserve system does help protect an
array of ecoregion- and local-endemic plant
and animal species and most of the alpine
and sub-alpine communities in the KSE
(Sawyer 2007), much of the ecoregion’s
biodiversity and many, if not most, of the
vulnerable species occur outside of the
existing protected area network.
Table 1. Area and percentage of north-facing late-seral and old-growth forest (collectively LSOG) in the Klamath-Siskiyou Ecoregion (KSE), southwest
Oregon and northern California, by climate change vulnerability zones, extant protected areas, and proposed conservation areas. Data for old-growth
forests for some portions of the ecoregion (southwestern coastal, southeastern border) were unavailable; thus, coastal old-growth forest area, inside and
outside of protected areas, is underestimated and the drier zone old-growth forest area to a smaller extent.
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72 Natural Areas Journal Volume 32 (1), 2012
Representation and Proposed
Prior reserve designs proposed for the
KSE include the Phase 1 reserves and
Representation Zones proposed by Noss
et al. (1999), the Siskiyou Crest National
Monument (KS Wild 2010) and Siskiyou
Wild Rivers (Sisikyou Project 2010) pro-
posed by conservation groups, and Scenario
3 Plan “interacting current and near-future
habitat” of Carroll et al. (2010). These
reserves, if implemented, would protect
a large proportion of the critical micro-
refugia within high-precipitation zones
and mesorefugia (i.e., 47% the remaining
old-growth forest and 22% of north-facing
old-growth; Table 1). If all the proposed
reserve expansions were implemented,
then 70% of remaining old-growth forest
and 33% of north-facing old-growth for-
est would be protected. We identiﬁed only
ﬁve gaps of highest priority and six high
priority microrefugia that were not fully
contained within the proposed protected
area network (Figure 3b). All of the highest
priority gaps are critically important sites
and should receive immediate conservation
attention. Collectively, these gaps contain
important coastal and intact old growth
areas, local pockets of species endemism,
and transitional areas; and they may pro-
vide additional mesorefugia corridors.
Additional and more ﬁnely resolved prior-
ity setting of microrefugia is warranted in
the near future. GIS-based spatial analyses
supported by ﬁeld evaluation of candidate
microrefugia can assess their species
assemblages, landscape context, terrain
position, habitat condition, defensibility,
and complementarity with other candidate
sites. These evaluations can be augmented
by additional analyses of past and future
refugia based on species distributions and
biophysical predictors of climatic and
vegetation stability and identiﬁcation of
areas predicted to experience wildﬁres
within historic ranges of frequency and
intensity. In addition, targeted surveys
of old-growth forest invertebrates and
non-vascular plants (e.g., fungi, lichens,
bryophytes) are needed to improve our
understanding of the distribution of distinct
assemblages in order to reﬁne the location
of mesorefugia and better design represen-
tative networks of microrefugia. Potential
refugia for the endemic serpentine ﬂora
need to be identiﬁed and prioritized. Such
areas are likely to be mesic serpentine sites
that remain relatively moist even under a
changing climate, due to terrain position
and other biophysical features (e.g., seeps
and bogs). The sites and their surround-
ing buffer habitats need to be identiﬁed
and prioritized using a similar approach
as for the old-growth forest microrefugia.
Identifying and protecting microrefugia
complements ongoing modeling of range
shifts for vulnerable species and natural
communities (e.g., Pearson and Dawson
2003; Loarie et al. 2008; Carroll et al.
2010; Damschen et al. 2010; Harrison et
al. 2010), studies of climate sensitivity of
species, analyses of how a changing climate
will affect wide-ranging species, and as-
sessing the cost and cost-effectiveness of
alternative conservation actions.
Large natural landscapes and wilderness,
the foundation of reserve designs, remains
the mainstay of conservation efforts in this
and many other localities and is especially
important in a changing climate. Without
large natural landscapes in relatively good
condition, many of the remaining pockets
of old-growth forest may not persist or
function well as microrefugia. However,
for ensuring a robust reserve design that is
responsive to climate change, it is prudent
to secure priority old-growth forest micro-
refugia as swiftly as possible while the
more time-consuming and uncertain task
of conserving larger landscapes continues.
Waiting decades for formal “gazettement”
of large protected areas without securing
microrefugia now may allow continued
degradation of these critical refuges. Our
recommended approach is somewhat novel
for most conservation advocacy, where
securing larger priority landscapes pro-
posed in comprehensive strategies is often
acted upon ﬁrst, but the rapidly warming
landscape may require a diversiﬁcation of
tactics. As Voltaire cautioned, we should
not let the perfect be the enemy of the
We greatly appreciate the contributions to
this analysis by the following individuals:
J. Cokendolpher, L. Farley, J.A. Johnstone,
J.M Ledford, R.A. Progar, J. Sawyer,
and W. Peterman. We thank KS Wild for
permission to use their ecoregion map as
a basemap, S. Harrison for reviewing an
earlier draft, K.E. Iron, and an anonymous
reviewer. This study was sponsored by a
grant to the Geos Institute from The 444-S
Foundation. The opinions expressed are
those of the authors and do not necessarily
reﬂect the views of 444-S Foundation.
David Olson is a Conservation Biologist
with Conservation Earth Consulting.
Dominick A. DellaSala is Chief Scientist
and President of the Geos Institute, Ash-
land, Oregon, and current President of the
Society for Conservation Biology, North
James R. Strittholt is the Executive Direc-
tor and Chief Scientist of the Conservation
Biology Institute, Corvallis, Oregon.
Reed F. Noss is the Davis-Shine Professor
at the Department of Biology, University of
Central Florida, Orlando, and the Presi-
dent and Chief Scientist for the Florida
Institute for Conservation Science.
Jamie Kass is a GIS specialist and con-
Thomas F. Allnutt is a Conservation Spe-
cialists with the Department of Environ-
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University of California, Berkeley.
Marni E. Koopman is a Climate Change
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