Ecology of whitebark pine in the Pacific Northwest

Transcription

1 Ecology of whitebark pine in the Pacific Northwest Gregory J. Ettl Director, Center for Sustainable Pack Forest College of Forest Resources University of Washington

2 Whitebark pine Overview Biogeography, succession Sample communities Climatic limitations using tree growth data Blister rust and mountain pine beetles Role of fire and climatic change in maintaining whitebark pine? Demographic modeling as a prediction tool

3 Continental Pacific Climate Pacific Climate Maritime Mediterranean

4 Coastal Mountains Olympic Mountains Cascade Mountains 3dparks.wr.usgs.gov/mtrainier/images/mr376 Agee, J.K Fire Ecology of Pacific Northwest Forests Crater Lake Nature Notes 1952

5 Cascades Klamath Warner Sierra Nevada ps/statewide/rainmap.pdf

6 Flora of North America Whitebark Pine s s Range Foxtail pine Great Basin bristlecone pine Limber pine

7 Subalpine Tree Species Washington & Oregon Cascade Range Species Northwestern WA Northeastern WA Central OR Subalpine fir M M M Mountain hemlock M - M Whitebark pine m M M Lodgepole pine - m m Engelmann spruce - m - Shasta red fir - - m Adapted from Franklin and Dyrness. Natural Vegetation of OR & WA

8 Montane Tree Species of WA & OR Cascade Range Species Western WA Eastern WA Northern OR Southern OR Whitebark pine - m m m Subalpine fir m M M - Mountain hemlock M M M M Lodgepole pine m M M M Shasta red fir M Western white pine m m m m Yellow cedar M m m - Engelmann spruce - m m m

9 Rocky Mountain Whitebark pine 10-15% 15% of subalpine Arno Chapter 4. Whitebark Pine Communities: Ecology and Restoration

10 Ecology of Pinus albicaulis (described from field data) 27 sites in North Cascades, Mount Rainier, and Crater Lake National Parks Vegetation plots, blister rust survey s Demographic data: cones and seedlings/saplings Tree rings used to describe growth response to climate

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12 Mount Rainier-August 1997

13 Whitebark Pine Ecology-Succession Eastern Cascade subalpine zone Seral species, often found on drier aspects or microsites Pacific Northwest: upper limit-- snowpack and temperature; lower limit out-competed

14 Mount Rainier Communities s

15 Whitebark pine Ecology WA and Landforms WA-Topography Ridges, and drier exposures more whitebark pine South and west > north and east Side-slopes, valleys, dominated by subalpine fir (mixed with Engelmann spruce & lodgepole pine)

16 Whitebark pine-southern OR Western subalpine mountain hemlock, and red fir (lower) dominate; minor component Eastern subalpine more whitebark pine Photo Photo by by Don Don Lawse Lawse

17 Crater Lake Whitebark pine 8000 Photo by Don Lawse

18 Growth Response of Whitebark Pine to Climate Regional growth study-washington and Oregon (Daneshgar SJU Thesis) Growth in WA is negatively correlated with winter and spring precipitation (a proxy for spring snowpack) Growth in southern OR is positively correlated with June temperature and July precipitation Long-term trends show growth increasing since about coincides with an increase in annual temperatures. CA study of whitebark pine, Inyo NF (Peterson et al and Alpine Research 22: ) 243) (Peterson et al Arctic Growth is positively correlated with snowpack (but older trees) and spring precipitation Long-term trends also show growth increase

19 Whitebark Pine Taxonomy Subgenus Strobus, section Strobi, subsection Cembrae (stone pines) Only North American stone pine 5-needle pine, indehiscent cones, mostly closed at maturity, wingless seeds John Schwandt

20 Whitebark Pine as a Keystone Species Food Source: Red squirrel, Chipmunk, Golden-mantled ground squirrel, Gray Jay, Stellar Jay, Raven, Black and Grizzly Bears, and Clark s s nutcracker

21 Clark s s Nutcracker-Whitebark Pine Mutualism Wingless, high fat content seeds Compulsive caching (32,000/bird/year) Cache times more than need Cache mature seed Select open, dry sites Only reliable germination

22 Threats to whitebark pine? Mountain pine beetles Fire suppression Climatic change Blister rust Waterton Lakes, BC Parks Canada

23 Mountain Pine Beetle Occurrence in whitebark pine stands Historically low in British Columbia, but expanding? (Campbell( and Antos 2000, Zeglen 2002.) Low in OR and WA, but (Shoal et al Common in California Sierra Nevada either active or past (Maloney( and Dunlap Is this drought or species composition?

24 Fire Dependent Communities? Mountain hemlock zone very infrequent (>300 years) -high severity fires (Agee( 1993) Lightning strikes increases east, but low transmission on drier sites (30-85 years? Siderius Murray 2005) Whitebark pine facilitates late successional species Siderius & Is the dominance of late successional tree species on montane sites due to fire suppression? Climatic warming has made more sites available: snowfields exposed

25 IPCC 2007 Global Land Surface Temperature Anomalies

26 Mote et al Scenarios for future climate in the PNW. Climate Impacts Group, University of Washington. Projected PNW Climate Change Temperatures to Projected changes increase across all in seasons: average largest annual PNW temperature temperature and increases precipitation (June- for August) the decades of the 2020s and Winter,, summer 2040s. Less snowpack 2020 s Temperature Precipitation Low 0.4 C -4 % Mean C + 2% High C + 6 % 2040 s Temperature Precipitation Low C - 4 % Mean +1.6 C + 2% High C + 9 % Based on 20 models. Benchmarked to the decade of the 1990s.

27 Subalpine Forest Response to Climatic Change Increased establishment of subalpine trees * Increased high elevation? *Rochefort et al Holocene 4:89-100

28 Whitebark pine and Climatic Change Northern range less snowpack should favor growth and establishment Oregon Cascades less summer precipitation drought stress? Sierra Nevada less snowpack drought stress, but also opens snowfields to establishment Fire? Mountain pine beetles?

29 Blister Rust Olympics and Cascades have had blister rust for 70 years? Spread to CA south through western white pine and sugar pine as well as whitebark pine (1944 Sierra Nevada and Adams 2003) Nevada-Kliejunas Lower infection levels in the eastern portion of many Pacific mountain ranges Progression or low humidity? McDonald, G.I., and R.J. Hoff Chapter 10. Whitebark Pine Communities: Ecology and Restoration

30 Cronartium ribicola Life Cycle Alternative host Ribes infection Pine infection

31 Severe growth reductions in infected and dead trees Live Mean Site Chronology Dead Individual Year

32 Average Cones/Tree North Cascades 2000 Mount Rainier 1997 Healthy Bole Infected 0.0 >50% crown loss Crater Lake High variability in cone production Infected trees produce fewer cones

33 Blister Rust and Establishment Higher levels 30-50% of adults Hillman Peak, Crater Lake Low levels <5% of adults Mt. Scott, Crater Lake Dead Infected Healthy Dead Infected Healthy South Pass, North Cascades Dead Boulder Butte, North Cascades Dead Infected Healthy Infected Healthy

34 Stage-based Model of Whitebark Pine Infected with Blister Rust Class 3 - Bole Infected Class 2 - Branch Infected Infection driver Class 4 - >50% Crown Loss 0.99 Class 1 - Healthy Adult Non-Reproductive Adult (N-RA) 0.90 Seed Infected N-RA year-old 0.56 Seedling Infection driver Infected Sapling 2 year-old Seedling 3 year-old Seedling year-old Seedling Sapling Infection driver Ettl and Cottone In Species Conservation and Management: Case Studies. Oxford University Press

35 Metapopulation with 2.5 km dispersal distance High Low Moderate Dispersal Distance (km) Dispersal Metapopulation with 12.5 km dispersal distance

36 Whitebark Pine Projections

37 Population Falls Below 100

38 Modeling Fire and Resistance Cottone 2001, SJU Thesis Fire-we modeled fire as a second catastrophe 50 year frequency killing 50% of all stages Maximizing seed germination Median time to quasi-extinction decreases (-28( years) Resistance buys more time Needle loss: that takes infected trees healthy (increases time to quasi-extinction ( years) Compartmentalization slower transition through infection (increases time to quasi-extinction ( years) Introducing resistant seedlings (> years)

39 Conclusions Whitebark pine ecology is variable across the Pacific mountain ranges-snowpack snowpack is important Blister rust is primary threat Mountain pine beetles and fire? Maintenance of whitebark pine communities appears dependent on developing or maintaining resistant trees

40 Acknowledgements Mark Burgman and Resit Akçakaya Regina Rochefort, Mary Rasmussen, NPS staff Paul DelPrato, Nicholas Cottone, Pedram Daneshgar & Molly Hammond Earthwatch volunteers Research supported by Howard Hughes Medical Institute, Sigma Xi, National Park Service & American Alpine Club, Earthwatch Center for Field Studies

41 Questions