| thinned - slash removed |  |
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| thinned - slash removed (partly) |  |  |
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| before thinning - after thinning |  |  |
Fairholme prescribed burn - mature lodgepole pine.
Banff National Park is conducting a large prescribed burn in the Fairholme range. FERIC has established a site with 3 plots (control, thinned and slash removal, and thinned only); to document the effect of stand density on fire behaviour. The site is dominated by lodgepole pine. It is located on a slope with very shallow soils.
| Control | Thinned and Slash Removal |
Thinned only, no slash removal |
Fuel samples and stand density parameter of the three sites were measured before and after the thinning; further samples will be taken after the site has been burned.
First results:
The measured fuel load as well as the density parameters and the critical Rate of Spread (ROS) can be found in Tab. 1 (below).
The fuel load in all three plots before the thinning (pre-treatment) is fairly similar (15.8 t/ha and 13.9 t/ha); only the slash plot has a lower fuel load on the ground before the thinning.
Density, Basal Area, Bulk Density and critical ROS also vary slightly. This is due to the inhomogeneous nature of forest.
The thinning has an enormous effect on the sample plots. The control site was not remeasured, as nothing has changed there. In the other two plots stand density and bulk density were lowered by circa 50 %; Basal area changed approximately -30%. Through this treatment the critical ROS increased by around 100% (7.37 to 13.45 in the no slash plot; 5.70 to 10.29 in the slash plot).
The fuel load on the ground has also changed. It increased in the slash plot to nearly 70 t/ha; in the no slash plot to 30 t/ha. Compared to the amount of fuel before the thinning this is a big increase. But it has to be kept in mind, that trunks of the trees were not totally removed (57.4 t/ha (82%) in the slash plot are trunks >7cm and 65% in the no slash plot). The amount of fine fuel (<7cm) did just increase slightly in the no slash plot and much more in the slash plot (as can be expected if no slash is removed).
Tab. 1:
| Plot | Fuel load t/ha | Density (stand) tree/ha |
Basal Area (stand) m2/ha |
Bulk Density (stand) (kg/m3) |
critical ROS |
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| PRE - TREATMENT | ||||||||
| <7 cm | >7 sound | >7 rotten | total | |||||
| control | 3.27 | 4.07 | 8.46 | 15.80 | 1004.4 | 40.18 | 0.4091 | 7.33 |
| no slash | 2.44 | 7.41 | 4.07 | 13.93 | 1127.7 | 36.18 | 0.4070 | 7.37 |
| slash | 1.29 | 0.55 | 0.33 | 2.17 | 1026.7 | 38.85 | 0.5265 | 5.7 |
| POST - TREATMENT | ||||||||
| <7 cm | >7 sound | >7 rotten | total | |||||
| no slash | 3.65 | 19.92 | 7.01 | 30.59 | 508.5 | 20.59 | 0.2230 | 13.45 |
| slash | 12.48 | 57.41 | 0 | 69.89 | 633.55 | 26.28 | 0.2916 | 10.29 |
Further procedure:
During the fire rate of spread (ROS) will be measured with ROS Data Loggers (stop watches with thermal sensors) and flame heights are measured and observed with In Fire Cameras.| thinned - slash removed | |
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| thinned - slash removed (partly) | | |
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| before thinning - after thinning | | |