Effectiveness of Mulching as a Fuel Treatment

Transcription

1 Effectiveness of Mulching as a Fuel Treatment Case Study at Red Earth Creek, Alberta Steven Hvenegaard, FPInnovations Dave Schroeder, Alberta Agriculture and Forestry October 19, 2015

2 Significance of fire Experimental burns have been conducted in fuel treatments with other fuel types Little documentation exists for effectiveness of mulching as a fuel treatment in Black Spruce Several mulch sites have been planned and created for experimental burns Conditions have not permitted burning Canadian Boreal Community FireSmart Project Rainbow Lake, Alberta 2

3 History of Red Earth Creek PB 2013 Planning and Design of REC PB site Fall 2013 Alberta Wildland Fuel Inventory Program inventory of blocks Winter 2013/14 mulching of Block 1 and 2 Spring 2015 continued site preparation and PB planning May 14, 2015 burn Block 1 3

4 Site Description 170 km north of Slave Lake 5 km east of Red Earth Creek 4

5 Block 1 100% Black Spruce, flat terrain Inter-tree spacing 0.71 ha Strip mulching 0.65 ha Untreated 1.35 ha North 5

6 Mulch Treatments Inter-tree spacing: from ~1650 to 250 stems/ha Strip mulch: 4 m strips, residual density 650 stems/ha Photos courtesy of McMaster University 6

7 Surface Fuels Treated areas were mix of mulch, mosses and Labrador tea Mulch: ~3kg/m 2 (strip), ~ 5 kg/m 2 (thin) Untreated Treated Photos courtesy of McMaster University 7

8 Ground Fuels Composition (%) - Major component is feathermoss - In spite of dead component in inter-tree, fuel moisture was retained - Frost line approx 0.5 m below surface Fuel Component Natural Stand Inter-tree Spacing Strip Mulching Dead Feathermoss Dead Fuscum Live Feathermoss Live Fuscum Litter Courtesy of McMaster University 8

9 mv reading from Theta probe Fuel Moisture (Moss) Relative MC from upper 3 cm layer FM = feathermoss Fusc = Sphagnum fuscum N = untreated T = inter-tree spacing S = strip mulch Courtesy of McMaster University FM-N FM-T FM-S Fusc-N Fusc-T Fisc-S 9

10 Fire Weather Weather and FWI values at time of ignition Red Earth lookout(4 km west of site) Dry spring, same weather pattern as 2011 Wind speed SE14 (average) with gusts to 22 km/h Temperature (Celsius) Relative Humidity (%) Wind Speed (km/h) Wind Direction (degrees) Hourly FFMC Hourly ISI DMC DC BUI Hourly FWI

11 Fire Weather Historical data (1981 to present) from Red Earth lookout Initial Spread Index (14) at time of ignition at 94 th percentile Highest recorded ISI (54) recorded on May 15, 2011 Build-up Index (48) at 81 st percentile Forecast Rate of Spread m/min (C2 fuel type) Forecast head fire intensity 13,000-18,000 kw/m 11

12 Ignition (helitorch) May 14, 2015 First strip - 14:17:14 to 14:18:08 Crown fire was initiated along ignition line within 30 seconds Completion of ignition line at 0:54 1:25 12

13 Fire Spread At 1:35 fire front has crossed into treated areas 13

14 Ember Transfer and Spot Fire Development 2:40 past ignition Spotting distance 70 to 80 m 14

15 Fire Progression 3:00 past ignition fire has spread 30 metres from ignition line into fourth mulch line (15m/min) 15

16 Fire spread through treatment areas Intermittent crown fire in strip mulch Time 3:15 (looking toward strip mulch treatment) 16

17 Fire Spread through treatment areas 3:00 past ignition vigorous surface fire HFI 4 (looking toward ignition line) 17

18 Aerial view at 5:20 Fire has passed through inter-tree spacing treatment ROS: m/min (to be validated) 18

19 Fire effects Thorough consumption of surface fuels and crown fuels At exit point of treatment area, blistering of White Spruce stems at 4.5 m height with scorch height at 7 m. 19

20 Fire Summary Strip mulch had little effect on fire behaviour Thinned stand had notable effect on intensity, but not ROS All trees candled ember source GROUND FUEL EFFECT? Dry Feathermoss tips along with mulch supported vigorous fire behaviour. Sphagnum clumps remained wet, could have had fine scale effect on fire behaviour(higher density sphagnum in natural had observed effect.). 20

21 Operational implications Existing strip mulch treatments need to be re-assessed. Treatment size needs to account for fast moving surface fire (mulch and dry feather moss will also result in HFI 4 intensity) Suppression tactics in fuel treatments should be considered in forest fuel treatments/community protection plans Resource deployments Water sources Guard construction Back burning 21

22 Next steps Develop mulch fire behaviour curves Test suppressant effectiveness Can something be done with feathermoss? Maybe thinning (sun) can promote sphagnum abundance displacing feathermoss Eco-site dependant? Scale up to make a difference? Compaction? FIRETEC runs Block 2 long term, burn in 5 years? Re-vegetation Mulch decomposition 22

23 Acknowledgements Alberta Agriculture and Forestry Project champion Slave Lake Wildfire Management Area planned and executed PB Canadian Forest Service Collected on site weather data and moisture samples Use data to calibrate FIRETEC model McMaster University Collected ground and surface fuel composition in Block 1 Measured fire effects on duff consumption Continues monitoring of post-burn recovery in Block 1 and posttreatment revegetation in Block 2 University of Toronto Developing and testing ember transfer data collection apparatus 23

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