Montague Bitzer Tract Treatment histories

Map of treatments in scrub oak units at the Montague Bitzer area. Click on a labeled treatment unit to read its history.

Map of treatments in scrub oak units at the Montague Bitzer area. Click on a labeled treatment unit to read its history. Map prepared by Matthew Duveneck.

The Bitzer tract is divided into a constantly-changing mosaic of treatment units. The units are edged with fuel breaks established by mowing with a Davco mower and range in size from less than an acre to 11 acres. In 2002 we began combining mowing (with the Davco) and burning treatments on some units. Mowing treatments are ongoing, and we hope to burn from 5-10 acres per year, spreading the burns out throughout the year. We hope to re-treat units on 10-year intervals.

This practice of managing small units and spreading management practices out over the year lessens the impact on any given wildlife species. If species exhibit a range of sensitivities to our treatments, it is better for each treatment to affect only a small area and to apply treatments throughout the year. This minimizes the adverse effects of the treatments while maximizing the diversity of the stages of scrub oak recovery. Vigorous young stands of scrub oak are high quality habitat for several species of state-listed Lepidoptera.

From a fuels perspective, results of our treatments indicate that we can reduce live plus dead fuel loads in over-mature stands of scrub oak from 25 tons/acre to 3 tons/acre in 12 months with a combination of mowing and burning. This is accomplished by mowing in the growing season, and then burning the area one year later.

We have recorded treatment histories of the units at the Bitzer tract; below are examples of a few units.

Back to top

Unit 1-2

Unit 1-2 (~1 acre) was burned on 5/1/2000, burned again in 2003, and fuel parameters (1x1m harvest plots and dwf lines) were sampled on 6/4/2004.

BehavePlus Input
Unit 1-2 Data from 6/4/04
1hr Fuel Load (dead) (tons/acre)
2.5
10hr Fuel Load (dead) (tons/acre)
2.9
100hr Fuel Load (dead) (tons/acre)
0
Live Woody Fuel Load (tons/acre)
1.38
Fuel bed depth (ft)
0.86

Unit 2-1

Unit 2-1 (~ 1.9 acres) was mowed (3 passes with the Davco) in 2002 and burned in 2003.

On 5/3/2005, we estimated the percentage of ground in Unit 2-1 that was covered by litter (and that we would thus be able to burn without severe threat of a ground fire) via 100m point-intercept transects. 80% of the surface of the unit was covered by litter, but for 20% there was only exposed duff. With this amount of exposed duff, a fire would probably carry well enough in the unit, but it could potentially get into the duff, greatly extending mop-up operations. It is likely that after another year, the unit will be safe to burn again.

Unit 2-2

Unit 2-2 (~1.6 acres) was mowed (1 pass with the Davco) in 2003, burned on 5/21/2004, and sampled (1x1m harvested quadrats and dwf lines) on 6/4/2004.

BehavePlus Input
Unit 2-2 Data from 6/4/04
1hr Fuel Load (dead) (tons/acre)
1.9
10hr Fuel Load (dead) (tons/acre)
1.8
100hr Fuel Load (dead) (tons/acre)
1.1
Live Woody Fuel Load (tons/acre)
0.0
Fuel bed depth (ft)
0.1

On 5/3/2005, we estimated the percentage of ground in Unit 2-2 that was covered by litter via 100m point-intercept transects. 53% of the surface of the unit was covered by litter, but for 47% there was only exposed duff. With such a high proportion of exposed duff, a fire would not carry well in the unit and could potentially get into the duff, greatly extending mop-up operations. For more information, see Unit 2-1. Unit 2-1 has a similar treatment history, but treatments began on that unit 1 year earlier.

Unit 3-11

Unit 3-11 (~1.9 acres) was mowed on 6/15/2004, burned on 9/15/2004, and sampled (1x1m harvest plots and dwf lines) on 9/23/2004. Note the large difference in fuel loads between this unit and unit 3-13, which received the same treatments but was sampled before the prescribed burn instead of after.

BehavePlus Input
Unit 3-11 Post-burn
Data from 9/23/05
1hr Fuel Load (dead) (tons/acre)
1.10
10hr Fuel Load (dead) (tons/acre)
0.04
100hr Fuel Load (dead) (tons/acre)
0.00
Live Woody Fuel Load (tons/acre)
0.00
Fuel bed depth (ft)
0.07

Back to top

Unit 3-13

Unit 3-13 (~1.4 acres) was mowed on 6/15/2004, sampled (1x1m harvest plots and dwf lines) on 9/23/2004, and burned on 9/23/04 as soon as sampling was completed. Note the large difference in fuel loads between this unit and unit 3-11, which received the same treatments but was sampled after the prescribed burn instead of before.

BehavePlus Input
Unit 3-13 Pre-burn
Data from 9/23/05
1hr Fuel Load (dead) (tons/acre)
6.01
10hr Fuel Load (dead) (tons/acre)
5.86
100hr Fuel Load (dead) (tons/acre)
0.72
Live Woody Fuel Load (tons/acre)
1.3
Fuel bed depth (ft)
0.58

Given the day-of-burn conditions, BehavePlus predicts a maximum Rate of Spread of 2.1 ch/hr and a maximum Flame Length of 1.7ft. The maximum temperature for the day was 78°F; the RH was 52%.

Day-of-burn conditions 9/23/05
Wind Speed (mph)
4.0
Flame length (ft)
1.7
Rate of Spread (ft/min)
2.1
Fuel Moistures (%):  
1hr
13.5
10hr
22.5
100hr
26.5
Live herb
103
Live woody
71.5

Back to top

Unit 5-1

Unit 5-1(~1.3 acres) was mowed on 6/23/2004 and burned on 5/18/2005. We conducted fuels sampling on 5/3/05, prior to the 5/18 burn (click here to see a photo of the burn). Below are the results of the sampling, in a format conducive to Custom Fuel Modeling in BehavePlus.

BehavePlus Input
Unit 5-1 Data from 5/3/05
1hr Fuel Load (dead) (tons/acre)
6.60
10hr Fuel Load (dead) (tons/acre)
3.90
100hr Fuel Load (dead) (tons/acre)
2.47
Live Woody Fuel Load (tons/acre)
0.60
Fuel bed depth (ft)
0.42

Given the day-of-burn conditions BehavePlus predicts a maximum Rate of Spread of 2.9 ch/hr and a maximum Flame Length of 2.1 ft. The maximum temperature for the day was 63°F; the RH was 38%.

Day-of-burn conditions 5/18/05
Wind Speed (mph)
4.0
Flame length (ft)
2.1
Rate of Spread (ft/min)
2.9
Fuel Moistures (%):  
1hr
9.7
10hr
15.4
100hr
19.0
Live herb
103
Live woody
71.5

The actual fire was quite hot and slow-moving with a fair amount of residual burning due to heavy slash loads (including 100-hr gray birch and red maple stems). Because of smoke concerns we had to proceed cautiously, but overall consumption was good. Click here to see a photo of the burn.

Back to top