The Future of our Boreal Forests. Mike Flannigan and Tim Lynham Canadian Forest Service

Transcription

1 The Future of our Boreal Forests Mike Flannigan and Tim Lynham Canadian Forest Service

2 Outline Recent climate - Climate change Impacts of climate change on forests primarily disturbances Options Summary

3 Proxy data also indicate that the recent warming is likely unprecedented in at least the past millennium Source: IPCC(2001)

4 Global surface temperatures are rising Degrees C Year Relative to average temperature

5 Canada is becoming wetter Percent change in precipitation

6 However, summers in some parts of North America have become much drier Summer Palmer (JJA) Palmer Drought Drought Severity Severity trends Index for (PDSI) Trends PDSI Trend indicates 95% significance denotes statistical significance OCCIAR at 95% Workshop level Sudbury Oct. 27,

7 Climate change pessimist or optimist

8 Are recent weather extremes due to natural variability or to climate change? Analyses suggest increases have occurred in many types of weather extremes in some areas, but not all Individual extreme events occur rarely and hence are difficult to link directly to specific causes However, many of the events are broadly consistent with climate change projections Hence these events are good examples of what may happen more often in the future

9 What is climate change? Climate change is a shift in climate relative to a given reference time period It is caused by: Natural factors -Solar variability -Volcanic dust levels -Internal variability -Geological change Human factors - Greenhouse gases - Aerosols -Ozone depletion -Land use change

10 The Greenhouse Effect Incoming Energy Reflected Energy Outgoing Energy Energy Trapped By Greenhouse Gases

11 CO2 Concentration (ppmv) CO2 concentrations are now unprecedented in at least the past 400,000 years $ Highest concentration in last 400,000 years $ $ $ $ $$$ $$$$!! $$ $$ #

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13 Climate Change & GCMs General Circulation Models (GCMs) are complex models not perfect but they are the best tools we have Observations above summer temperature changes below Greatest increases in temperature will be at high latitudes, over land and winter/spring Projected increases in extreme weather droughts, ice storms, wind storms, flooding etc. Spatial and temporal variability in climate change

14 Climate change and Forests Carbon dioxide increases increased growth? Increased temperatures increased growth? More flexibility in growing stock? Variable weather winter thaws, late spring frosts, early autumn frosts, extreme cold outbreaks, More drought - likely Changes in disturbances fire, insects, disease, wind, ice storms Impacts on wildlife Winter roads - permafrost

15 Quick facts on Canada s forests 40% of Canada s surface area 400M hectares jobs 1.9% of the GDP + non-economic values Management under shared jurisdiction: 77% P/T; 16% GoC; 7% private Forests are climate sensitive

16 CC impacts are already evident Spruce beetle Smoke emission Mountain pine beetle Spruce budworm Wildfires Windtrows / blowdown Drought Aspen Dieback Winter harvesting problems Increased productivity??

17 Disturbances in Canada annually: 418 million ha of total forest (60% is productive timber) Disturbances -Catalyst for change Harvesting: 1 million ha Fire: 1 to 8 million ha Insects: 10 to 25 million ha Mike Maksimchuk Alberta SRD

18 Million hectares burned Canada Annual Area Burned Year Canadian Fire Statistics Incomplete prior to 1970 Currently - average of 9000 fires a year burn 2.3 million ha Area burned is highly episodic 0.4 to 7.6 million ha Lightning fires 35% of total fires represent 85% of area burned Fire size 3% of fires are >200 ha represent 97% of area burned

19 Large Fires in Alaska and Canada Fire polygons kindly provided by Canadian Fire Agencies (Provinces, Territories and Parks Canada) and the state of Alaska

20 Forest Fires 4 Key Factors Fuel - loading, moisture, structure etc. Ignition - human and lightning Weather - temperature, precipitation atmospheric moisture and wind; upper atmospheric conditions (blocking ridges) Humans - land use, fragmentation, fire management etc.

21 Fire Issues An average of $700 million spent by fire management agencies in Canada a year on direct fire fighting costs Health and safety of Canadians evacuations - smoke Property and timber losses due to fire Balancing the positive and negative aspects of fire ( the Smokey Bear Syndrome) Kyoto or post-kyoto

22 Fire Ecology Boreal forests survive and even thrive in semi-regular high intensity fires (stand renewal) Removes competition Prepares seedbed Survival strategies - Cone serotiny, vegetative reproduction and bark thickness Role of fire suppression Smokey syndrome

23 Area burned and Temperature Area burned in Canada is strongly related to warming Impacts of climate change are here already A warmer future means more fire in Canada

24 Percentage increase in total number of fires (relative to )

25 Area Burned Projections CCC 3xCO 2 Hadley 3xCO 2 Projections of area burned based on weather/fire danger relationships suggest a % increase in area burned by the end of this century according to the Canadian and Hadley models respectively

26 Fire and Weather Feedbacks: potentially positive Degrees C Fossil Fuel emissions: increase greenhouse gases Year Cause warmer conditions Weather becomes more conducive to fire: more fire Carbon released from more fire enhances greenhouse gases further

27 GCMs Seasonal Severity Rating

28 What Will Increased Severity Do? This will influence the type of fire: higher intensity = crowning sooner, deeper depth of burn, reduced suppression effectiveness, may lead to larger fire sizes.

29 Length of fire season CCC 3xCO 2 Hadley 3xCO 2 Fire season length increases by days over much of the boreal according to the Canadian and Hadley GCMs

30 More fires in the far north SPOT VGT Satellite Fire Mapping 2003

31 Future Fire: More fire growth (weather) More ignitions (human, lightning) Fuel effect uncertain Suppression effectiveness uncertain Will the warming cause more fire, increasing CO 2 emissions, and increase the warming? But, many of our forest ecosystems have evolved with fire. How much fire do our forests need? And how much can they handle?

32 Adaptation Strategies Fire exclusion not an option in many regions aspen spruce Landscape fuels management Fuel conversion Fuel reduction Fuel isolation FireSmart landscapes Strategically located firebreaks Education, prevention Emergency planning Level of protection studies

33 Spruce Budworm (Choristoneura fumiferana) Most destructive forest pest in boreal forest Hosts: firs, spruces 35 million m 3 /yr 35 yr cycle we re heading into max at the same time as mountain pine beetle

34 Projected (2100) changes in spruce budworm outbreak characteristics due to climate change (D. Gray, Can. Forest Serv.)

35 Spruce budworm in the future boreal forest WARMER, DRIER, MORE HEAT WAVES & DROUGHTS SBW SURVIVAL & FECUNDITY INCREASE Influence on SBW population dynamics: a) average densities in short-term, but what long-term effect on complex foodweb & outbreak cycle? b) increased rate of population growth SBW escapes its natural enemies more easily? More frequent & severe outbreaks?

36 Annual area affected by MPB ( x 10 3 km 2 ) More insects outbreaks: ex: Mountain pine beetle in BC Kurz et al. 2008

37 And more to come? Current climatic domain Future climatic domain? Potential domain Pinus contorta Pinus banksiana MPB Carroll et al. 2007

38 W. Kurz (PFC 2010)

39 Future Distribution of Species Spatial modelling, analysis, databases integrating ecology, economics and climate change Dr. Dan McKenney Plant Hardiness project distribution 5-95% Sugar maple Current CGCM2 A

40 Forest dieback in Alberta and Saskatchewan ( ) Major cause: Prolonged drought Severe dieback in aspen parkland Many dead and dying conifers and aspen Full impact not yet determined Photo by M. Michaelian

41 Permafrost Current distribution of permafrost in Canada Under 2xCO 2 scenario Impact of Climate Change on Permafrost in Canada M.W.Smith, K.Henry, D.W.Riseborough, Carleton University, Ottawa

42 Predicted changes to Canadian boreal forests certain areas convert to grasslands (where >4 o C increase) less old-growth forest northward movement of forest types disturbances as a catalyst for change increased prevalence of jack pine and aspen; and reduced balsam fir and white spruce = homogenization of landscapes

43 IBIS: Simulated changes in major vegetation types Polar desert/rock/ice Desert Tundra Open shrub-land Dense shrub-land Grassland Savanna Mixed forest Boreal deciduous forest Boreal evergreen forest Temperate deciduous forest Temperate evergreen forest

44 Canada s Biomes Predicted ecosystems by 2100

45 Disturbance Compensation: Can we win? Hadley 3xCO 2 Our management strategies buy time!

46 Adaptation to changes in forest management (1) greater attention to temperature adaptation in seedlings and seeds (climate-based zonation) increased attention to genetic hardiness and selective breeding of tolerant types increased effort to maintain gene diversity (mixed provenances) re-assessment of current seed orchards breed for pest resistance

47 Adaptation to changes in forest management (2) more mixedwood management (reduce infestation) assisted migration for commercial species too slow to respond increased fire protection of high value stands and landscapes

48 Conclusions The evidence for a changing climate is clear Humans are likely the primary cause for recent changes The climate will get MUCH warmer and more variable What does the future hold for our forests? More stress More weather extremes More disturbances Exotic pests Managed forests more resilient than natural forests? Are we reaching a tipping point?