Climate Trends in Northern California: How Do We Manage for the Future?

Transcription

1 Climate Trends in Northern California: How Do We Manage for the Future? Forest Management and Watershed Science Symposium April 30, 2013 Kyle Merriam, Sierra Cascade Province Ecologist, USDA Forest Service, Pacific Southwest Region. phone: (530)

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5 Outline Observed trends in climate in Northeastern CA Observed trends in climate-driven processes: hydrology, fire, vegetation Projected future trends Management options

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7 North, Malcolm, ed Managing Sierra Nevada forests. Gen. Tech. Rep. PSW-GTR-237. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 184 pp.

8 Observed Trends in Climate Weather Station Data Spatial Climate Grid Data (PRISM) Remote Automated Weather Station

9 California Weather Stations Miles. COOP and RAWS Stations: Western Regional Climate Center

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11 Climate Regions Region Central Coast Mojave Desert North Central North Coast Northeast Sacramento Delta San Joaquin Valley Sierra Sonoran Desert South Coast Southern Interior Miles Abatzoglou et al. 2009

12 Trends in Temperature: Weather Stations Northeast Climate Region

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14 Trends in Temperature: PRISM Mean temperature change between the 1930 s and 2000 s

15 Alturas Temperature Trends:

16 Susanville Temperature Trends:

17 Portola Trends in Temperature: Months Below Freezing

18 Precipitation

19 Trends in Precipitation: Weather Stations Northeast Climate Region

20 Trends in Precipitation: Weather Stations Susanville Hat Creek

21 Trends in Precipitation: PRISM Mean precipitation change between the 1930 s and 2000 s

22 Trends in Precipitation: Variation Northeast Climate Region

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24 Trends in Snowfall: Weather Stations Station Climate Region Total Annual Snowfall Mineral North Central NS De Sabla North Central -53***, R 2 =0.23 Alturas Northeast NS Cedarville Northeast -48***, R 2 =0.42 Hat Creek Northeast -38***, R 2 =0.26 Susanville Northeast -62***, R 2 =0.41 Portola Northeast -31*, R 2 =0.08 Quincy Sierra -50*, R 2 =0.09 Strawberry Sierra NS

25 Trends in Snowfall: Snow Surveys California Cooperative Snow Surveys:

26 Trends in Snow Water Equivalent From , Moser et al. (2009)

27 Summary of Observed Trends Increasing temperatures at regional scale: varies by location No significant change in precipitation at regional scale: varies by location Increasing variation in precipitation Decreasing snow pack

28 Observed Climate Related Trends Hydrology Fire Vegetation Insects/disease Wildlife

29 Observed Trends: Hydrology Loss of winter snow pack Peak run-off occurring days earlier Particularly for watersheds near winter freezing temperatures Volcanic basins (Pitt River watershed) may be somewhat buffered

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31 Observed Trends: Fire

32 Sierra Nevada: Trends in fire area and severity 140 Annual burned area 2500 Mean fire size Hectares (thousands) 120 Fire suppression Hectares Hectares (thousands) Year Total burned area 10yr Moving Avg A Max. fire size Year Maximum Fire Size 10yr Moving Avg C % High Severity Year Average Fire Size 10yr Moving Avg B Forest All Forest fire Types severity R 2 = 0.465, P (lin.) = % High Severity 10Yr Moving Avg Mapped Burned Ha Ha Miller et al. 2009

33 Klamath Mountains: trends in fire area and severity Hectares (thousands) Annual burned area 1987: 185,851 ha 2008: 212,819 ha Hectares Mean fire size Total burned area 11 yr Moving Avg Mean fire size 11 yr Moving Avg Max. fire size 70 NS Forest Fire Severity Hectares (thousands) % High Severity Ha Miller et al., in review Max fire size 11 yr Moving Avg % High Severity 10Yr Moving Avg Total Burned Area

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36 Observed Trends: Vegetation Distribution of major vegetation types in (A) and 2000 (B), from Bouldin (1999).

37 Observed Trends in Forest Structure: Increased density, cover and basal area More small trees, fewer large trees Increased mortality of large trees in most forest types More shade tolerant species Decreased mortality rates for some subalpine species Decreased spatial heterogeneity Bouldin (1999), Van Mantgem (2009), Dolanc et al. (2012)

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39 Observed Trends in Forest Structure: The Role of Climate Increased temperature and precipitation favor regeneration and recruitment Increased drought stress causes largetree mortality Higher CO 2 and temperatures has favored some subalpine species

40 Observed Trends in Vegatation: Juniper Invasion

41 Observed Trends in Insects and Disease

42 National Audubon Society (2009)

43 Observed Trends in Wildlife Geographic ranges shifted up in elevation Some high-elevation species exhibited range contraction Several low-elevation species expanded their range upslope Species responses differed Moritz et al. (2008)

44 Summary of Observed Trends Earlier peak run-off Increased fire activity Shifts in species composition and distribution Denser forests with more small trees Increased mortality of large trees* Increased insects and disease Wildlife species moving north/upslope and range contraction

45 Summary of Projected Future Trends Increased temperatures Lower snowpack, earlier runoff, more extreme events Increased fire size and extent Increased drought stress Expansion of juniper and invasive grasses Increased insects and disease Range contraction of wildlife species

46 Projected Future Trends: Vegetation Southern Cascades B Lenihan et al. (2008). Modoc Plateau

47 Management Options Reduce non-climatic stressors Decrease stand densities, particularly of small trees Reduce fuel loads Restore hydrologic systems, wetlands Restore stream bank vegetation Protect intact habitats, corridors, reduce fragmentation

48 Management Options: Can the past inform the future? The past may give us insight into how things work Ecosystems are dynamic over time Specific species or habitats that occurred in the past may not occur in the future Processes that promoted resilience in the past are likely to do so in the future

49 From Millar and Woolfenden (1999)

50 From Millar and Woolfenden (1999)

51 Predicted Refugia

52 Heterogeneity From Kane et al. (2013)

53 Photos courtesy of Carl Skinner, PSW Redding

54 Lessons From the Past Manage for habitat connectivity and migration corridors as climate refugia Manage for increased heterogeneity Forest structure Wildlife habitat Fuel loading Species composition Restore ecological processes, such as fire

55 Summary of Management Options Enhance ecosystem resilience and sustainability by removing or reducing non-climate related stressors Historical ecology can provide insight into the way things work rather than the ways things were Focus on restoring process (e.g., fire, hydrology) rather than structure A key management focus should be restoration of heterogeneity

56 Thank you! Questions?