California Forest Health: A Practical Approach

Transcription

1 California Forest Health: A Practical Approach

2 CASE STUDY IN MANAGING FOREST HEALTH ISSUES: LAKE TAHOE BASIN

3 Fuels treatments and their ecological effects: the Angora Fire as a case study Hugh Safford, USFS, Pacific SW Region; Dept. Env. Science & Policy, UC-Davis

4 California 399 Incline Village Tahoe City Nevada 2633 Lake Tahoe 1899 m Angora Fire 2968 South Lake Tahoe Meyers 3317 N W E S km Lake Tahoe Basin, California and Nevada, with the location of the Angora Fire. Outer polygon demarcates the boundary of the USDA-Forest Service Lake Tahoe Basin Management Unit.

5 June 24-27, 27 3,72 acres/1,243 ha 254 homes lost $16,, total cost 48 acres/194 ha fuels treatments Comm/precomm thin, hand thin, pile, pile burn Forest Mtn Rd Mule Deer Tahoe Paradise

6 Field Methods Point-center-quarter transects sampled July-September, 27 and 28 Transect length 25 to 525 m, 1-21 sampling pts each. Random distance intervals (between m). Variables measured 27: species, mortality, dbh, ht, scorch ht, torch ht, bole char ht, % crown scorch, % crown torch Variables measured 28: mortality, beetle attack, % green crown, needle litter, understory cover and diversity, seedling density 82 Common Stand Exams 28, 81 m 2, on 4 m grid >2 regeneration plots, 5 m 2, on 2 m grid

7 Transects N km Fire severity map of Angora Fire, with locations of field transects (numbered). RdNBR-based estimate of mortality by basal area, postfire imagery from days after fire. Red = high severity (>75% mortality), yellow = moderate (25-75% mortality), green = low (<25% mortality); Blue = very slightly burned to unburned. Hachured polygons are completed fuels treatments, polygon without hachuring is Unit 2, where handpiled fuels had not been burned. Lower circled area is Tahoe Paradise area, middle circle identifies Unit 2, upper circle encompasses transects in Units 16 and 17. Box number 3 overlays the firestart location.

8 Stand Exams We analyzed 37 that occurred in treatments or within 1 m of their boundary

9 Treatment Unit 22 Neighboring untreated

10 Angora Creek area: Tahoe Paradise Untreated Area North Fuel Treatment Units 21 and 29

11 1. Area of Transect 1: no treatment, 1% mortality 2. Area of Transect 2: treated for fuels , 1% mortality

12 Comparison of treated vs. untreated forest, Angora Creek: Crown Scorch and Crown Torch 12 ca. 37 meters 1 Percent of canopy % Crown Scorch % Crown Torch 2 Untreated Treated Sampling Point Transect % Crown Scorch % Crown Torch Percent of canopy 2 Untreated Treated Transect 4 Sampling Point

13 Scorch height and bole char height 25 ca. 37 meters 2 Meters 15 1 ScorchHt CharHt 5 Untreated Treated Sampling Point Transect 3 ca. 5 meters 35 Untreated Treated 3 25 ScorchHt CharHt 2 15 Meters 1 5 Live 28 Untreated Treated 1. Live 27 Transect Proportion surviving fire Sampling Point Transect 4 Sampling Point

14 Forest Mtn Road T r e a t e d Unit 17 Unit 16 Fire Spread North

15 North Fire Spread Unit 17 Unit 16: >3% slope, hand thinned only Unit 17: <3% slope, mechanically thinned

16 3. Transect 7: looking NE at Unit 17 from untreated 4. Tr. 5: looking into Unit 16 from Unit 17 bdry 5. Tr. 5: looking into Unit 17 from Unit 16 bdry (same pt as photo 4)

17 Comparison of treated vs. untreated forest, Forest Mtn Road area ca. 25 meters ScorchHt CharHt Meters Untreated 7 6 Treated Transect 7 Sampling Point Untreated Treated 12 1 % Crown Scorch % Crown Torch Percent of canopy Live 28 Untreated Treated 1. Live Proportionsurvivingfire Transect 7 Transect Sampling Point Sampling Point

18 Comparison between Unit 16 and 17, Forest Mtn Road area 35 ca. 25 meters 3 25 Meters 2 15 ScorchHt CharHt 1 5 Trtmt 16 Trtmt Sampling Point Transect 6 12 ca. 25 meters 1 Percent of canopy Trtmt 16 Trtmt 17 PctCrwnSc PctCrwnTo Proportionsurvivingfire Untreated Treated Transects 5 and 6 Sampling Point Sampling Point Transect 6

19 Mule Deer Circle Unit 2: Unburned hand piles 6. Tr. 1: looking SW from treated area toward untreated

20 Comparison of treated vs. untreated forest, Mule Deer Circle area (Unit 2) ca. 4 meters 12 1 % Crown Scorch % Crown Torch Percent of canopy Untreated Treated Transect 9 Sampling Point ca. 4 meters ScorchHt CharHt 2 15 Meters Untreated Treated Transect 1 Sampling Point

21 Tree density and basal area Trees > 5 dbh Meandensity (trees/ha) Treated Untreated PIJE ABCO CADE PICO ABMA PILA All spp All stems Basal area (sq m/ha) Taylor 24 Treated Untrtd

22 1 Tree mortality. A: transects; B: species Proportionsurviving Treated 27 Treated 28 Untreated 27 Untreated 28 Proportionsurviving Transect Untreated: % drop in survival Treated: 3% drop in survival ABCO ABMA CADE PICO PIJE Grand Total A Treated 27 Treated 28 Untreated 27 Untreated 28 B

23 Predicted long-term mortality Untreated Treated PIJE ABCO Predicted 3-year mortality, trees that were still alive in 28 Ryan and Amman (1994) 3-yr mortality probability P(mort) = 1/{1 + e [ (bark factor + crown factor)] } Bark factor = 6.316[1 e (-.3937BT) ] Crown factor = -.535(CVS 2 ) BT = bark thickness in cm = v(diameter at breast height in cm), where v is a constant, given in Reinhardt and Crookston (23)

24 Red turpentine beetle attack meters (ht), centimeters (dbh) RTB height No RTB height RTB dbh No RTB dbh 1 Untreated Treated Attack rate Untreated: 23/63 = 37.1% Treated: 24/127 = 18.9%

25 Soil cover Mean litter cover 28, data from transects and data from CSE plots Untreated Treated Trans. Plots Yellow pine forests (Johansen et al. 21): major erosion threshold reached at >6% bare ground

26 16 Other variables * Grass/forb species (#) Grass/forb cover (%) Shrub cover (%) 4 2 * Treated Untreated Dist. to seed tree (m) Shrub sdlg density * * -5 Treated Untreated

27 Summary 1. In almost all cases, completed fuels treatments had a strong effect on fire severity Fire moved from the tree canopy to the surface Vertical extent of crown torching, crown scorching, and bole char was much greater in the untreated areas Within untreated sample areas, crowns in most trees (66%) were completely scorched, and 4% of trees had >9% of their crowns combusted by fire Magnitude of effect less where fire weather conditions were less severe and where treatments were not complete 2. Fuels treatments significantly decreased tree mortality 28 tree mortality was 67% in untreated areas vs. 36% in treated areas (excl. Unit 2; 2% if Unit 16 excluded) Additional mortality between 27 and 28 much greater in untreated stands Predicted 3-year mortality +/- 2x higher in untreated vs. treated stands 3. Treated forest has suffered lower rates of turpentine beetle attack But beetle focus on larger trees is heightened in treated stands

28 7. Forest regeneration Few canopy trees in untreated areas are likely to survive in the longterm Very low density of living seed trees in untreated stands Very few seedlings in fire area due to early fire and coincidence with poor seed crop High shrub seedling density in untreated areas will result in chaparral dominance of many of these stands for many decades Summary (cont.) 5. Major differences in soil litter cover Treated stands showed >2x greater litter cover Mean litter cover in untreated stands is at or below 3-4% (Johansen et al [21] threshold for major erosion impacts of heavy rainfall) 6. Understory effects One year after fire, treated stands supported much higher understory species diversity than untreated stands Live herbaceous cover was low in both areas, but about 7% higher in treated stands Shrub seedling density much higher (9x) in untreated forest

29 Acknowledgements: Funding: LTBMU Data collection: Dave Schmidt (TNC), Sol Dobrowski (Univ. Mont.) Chris Carlson (Univ. Mont.) Randy Striplin (LTBMU) Data Analysis: Chris Carlson (Univ. Mont.) THANK YOU

30 CASE STUDY IN MANAGING FOREST HEALTH ISSUES: LAKE TAHOE BASIN

31 re Management and Forest Restoration in the Lake Tahoe Basin Welcome 1. Why now? 2. The Challenge of forest management on non-federal lands in the Tahoe Basin. 3. Forest conditions on non-federal lands in the wildland urban interface. 4. Goals of fuels reduction projects implemented by the Tahoe Fire and Fuels Team. By: John Pickett, Operations Manager Tahoe Fire and Fuels Team

32 Angora Fire at 7P.M. on June 24

33 Southern Nevada Public Lands Management Act $5.4 Million Allocated to six Fire Protection Districts: 1)Initial treatment of approximately 1 acres in the WUI 2)Stipend for 1 homeowners for defensible space 3)Chipping on approximately 3, residential lots

34 Tahoe Fire and Fuels Team MAC Informatio n Officer Incident Comman der Operations Finance Plans North Branch South Branch Technical Specialist Fire Safe Council Technical Specialist Fire Safe Council NLTPFD Tahoe Douglas NTFPD SLTFD LVFPD Fallen Leaf Meeks Bay FPD

35 North Tahoe Fire Protection Dist.

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37 Rubicon Bay West Shore

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39 Rubicon Bay West Shore

40 Rubicon Bay West Shore

41 Rubicon Bay West Shore

42 Rubicon Bay West Shore

43 Rubicon Bay West Shore

44 CASE STUDY IN MANAGING FOREST HEALTH ISSUES: LAKE TAHOE BASIN

45 FOREST HEALTH, LAND-USE, AND ENVIRONMENTAL CHANGE IN THE LAKE TAHOE REGION Patricia Maloney 1, Detlev Vogler 2, Camille Jensen 1 1 Department of Plant Pathology, UC Davis; 2 PSW Research Station, Institute of Forest Forest Genetics

46 NATURAL AND ANTHROPOGENIC THREATS TO WHITE PINES FROM LOWER MONTANE FORESTS TO SUBALPINE WOODLANDS OF THE LAKE TAHOE BASIN: AN ECOLOGICAL AND GENETIC APPROACH APPROACH FOR CONSERVATION, MONITORING, AND MANAGEMENT. (VOGLER & MALONEY SNPLMA ROUND 7) 7 WPBR HISTORICAL LOGGING CLIMATE FIRE & FIRE SUPPRESSION MOUNTAIN PINE BEETLE

47 SUGAR PINE & HISTORICAL LOGGING Glenbrook 19 Extensive logging dramatically changed the structure & composition (Lindstrom et al. 2; Manley et al. 2). Historical composition: 2-25% (in some locations, Lindstrom et al. 2). Present-day composition: 1-6% (Barbour et al. 22; Lindstrom et all. 2). Glenbrook 1998 Population & genetic 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 and environmental change (e.g., WPBR, MPB, climate). Photos courtesy of David Fournier - LTBMU

48 Sugar Pine, Fire Suppression, & WPBR Stand densification Large overstory SP Suitable conditions for WPBR Limited regeneration Granlibakken Sugar Pine Incidence of WPBR = 48% J-shaped curve often indicative of a declining population seedling >41. Size class (cm dbh)