Natural and anthropogenic threats challenging white pines of the Lake Tahoe
Basin:
How do we conserve, monitor, and manage important forest tree species?
WPBR
Patricia E. Maloney1 and Detlev R. Vogler2
2Institute
1Department of Plant Pathology, University of California, Davis, CA 95616
of Forest Genetics, USDA Forest Service, PSW Research Station, Placerville, CA 95667
FIRE
MPB
CLIMATE
HISTORICAL LOGGING
Hydrologic
functions/
Watershed
protection
Wildlife habitat
Photo: Deems Burton
Biological diversity
Important food resource
WHITE PINE BLISTER RUST
Photo: Detlev Vogler
Photo: Detlev Vogler
Pinus lambertiana (Sugar Pine)
<10%
White Pines & WPBR in the
Lake Tahoe Basin
Pinus monticola
(Western White Pine)
30%
Pinus albicaulis
(Whitebark pine)
40%
Map courtesy of USFS - LTBMU
WPBR: Demographic
effects
• Juvenile mortality
• Reduced fecundity
• Lower recruitment
• Reducing dispersal
and establishment
potential
X
X
CLIMATE
sugar
pine
western white
whitebark
present
2030
Bioclimatic models courtesy of M. Warwell, G. Rehfeldt, & N. Crookston - Rocky Mountain
Research Station
HISTORICAL LOGGING & SUGAR
PINE
Glenbrook 1900
Glenbrook 1998
Photos courtesy of David Fournier - LTBMU
•
Extensive logging dramatically changed
composition and structure (Lindström et
al. 2000, Manley et al. 2000).
•
Historical composition: 20-25% (in
some locations, Lindström et al. 2000).
•
Present day composition: 1-6% (Barbour
et al. 2002, Lindström et al. 2000).
•
Genetic and population consequences:
effects on population structure and
dynamics, but also genetic structure and
diversity. Population and genetic losses.
•
Such losses may affect sugar pine’s
resilience to disturbances (e.g., WPBR,
MPB, climate).
Climate-driven outbreaks of native insects MPB
•
MPB preferentially attacks
drought-stressed trees.
•
In high elevation forests we see
evidence of MPB and mortality
(current and historical) but at low
levels and often associated with
protracted drought periods. Some
exceptions.
•
Currently - areas of MPB activity
in the LTBMU (will need to
monitor).
•
California Mediterranean climatic
regime and drought adaptation and
tolerance.
•
Water-use efficiency and host
suitability to native insects?
Fire and Fire Suppression
•
Catastrophic wildfire and potential
loss of important and rare
genotypes (e.g., WPBR resistant).
•
Prescription fires and loss of large
reproductive pines (white and
yellow).
•
Fire-climate interactions:
lengthening of the fire season
(advancing start and ending later).
I. CONSERVATION:
Genetic Conservation and Genetic
Evaluations
¾ Basin-wide cone collections of sugar,
western white and whitebark pine.
¾ Seed-bank of white pine species for the
LTBMU for conservation, reforestation,
and restoration.
¾ WPBR resistance evaluations
and screening. (IFG and Placerville
Nursery).
¾ Genetic diversity (neutral) of LTBMU
white pine populations - standing adults
and next generation (NFGEL/IFG).
¾ Future work: Genomic analyses to
determine adaptive genetic diversity of
important plant traits to determine
adaptive potential (Neale Lab-UCD).
II. MONITORING:
White Pine Populations
We will be establishing a robust baseline dataset from which to monitor
future changes in:
800
Suwanee Creek
600
Stem count
800
Observed
Projection 1983-1988 data
Projection 1988-1994 data*
Projection 1994-2000 data*
700
400
400
300
300
200
200
100
100
¾ Population dynamics & demographic trends
0
1980 1990 2000 2010 2020 2030 2040 2050
700
Observed
Projection 1991-1996, 1992-1997 data
Projection 1996-2001, 1997-2002 data
600
500
800
Crystal Road
700
500
Hodgedon Meadows
0
1980 1990 2000 2010 2020 2030 2040 2050
800
Observed
Projection 1991-1996 data
Projection 1996-2001 data
700
600
600
500
500
400
400
300
300
200
200
100
0
1980 1990 2000 2010 2020 2030 2040 2050
Crane Creek
Observed
Projection 1993 - 1998 data
100
0
1980 1990 2000 2010 2020 2030 2040 2050
Year
¾ Recruitment dynamics (inclusive of cone production)
¾ WPBR resistance frequency
¾ Mortality
¾ Genetic diversity (neutral and adaptive)
¾ MPB
¾ WPBR wave years
III. MANAGEMENT:
Restoration Recommendations and Potential Mitigation
Strategies
Based on demographic
trends/models and
genetic diversity assessments,
restoration
will be recommended if:
1. Populations are in decline (due
to wpbr, climate, wpbr x climate).
2. Depauperate genetic base (e.g.,
genetic losses due to selective
logging).
¾ Deploy genetic material
that is broadly adapted,
wpbr-resistant, and
physiologically
(e.g.,WUE) suitable for
present and future biotic
and abiotic conditions.
¾ Develop appropriate
restoration strategies
for successful
establishment, growth,
and resilience.