Table 1 Burn date, weather, soil and fuel moisture, and fire behavior during prescribed burning for the burn treatments at the Bluebunch site, Steens Mountain, Oregon, USA. All juniper trees (>1.5 m) were cut in July 2006 in the JAN, MAR, and APR treatments. The SEP treatment was a partial cut (one third of trees >1.5 m tall were cut), fire killing the remaining live trees. Treatment means with different lower case letters are significantly different within rows (P < 0.05).

Weather

Temperature (°C)

20 to 27

3.5 to 5.5

3.5 to 5.5

5.0 to 7.0

Relative humidity (%)

11 to 15

40 to 50

67 to 75

23 to 30

Wind speed (km hr⁻¹),

2 to 4, SW

0 to 2, SW

1to4, NE

6 to 13, SW

Sky

Clear

Clear

Overcast to snow

Clear

Soil water content (%) ¹

Slash

12.4 ± 1.3a

32.8 ± 0.4c

29.6 ± 1.6c

24.3 ± 2.2c

Canopy

13.4 ± 1.1a

33.2 ± 0.9c

30.4 ± 1.2c

16.3 ± 1.0b

Interspace

11.9 ± 0.5a

32.8 ± 1.6d

26.1 ± 1.9b

17.1 ± 1.3b

Fuel moisture (%)

Herbaceous

10.1 ± 0.2a

28.3 ± 1.4c

45.2 ± 3.3d

22.9 ± 3.2b

Juniper needles

Suspended ²

6.7 ± 0.5a

9.3 ± 1.1b

11.9 ± 0.9b

5.8 ± 0.4a

Ground surface ³

9.2 ± 0.3a

35.6 ± 4.2c

37.8 ± 4.2c

11.1 ± 0.4b

Canopy mat

21.0 ± 3.4a

64.1 ± 11.6b

73.9 ± 12.8b

25.3 ± 0.6a

Cut juniper roundwood ⁴

1-hour

10.7 ± 1.2a

12.1 ± 1.1a

16.8 ± 1.7c

13.7 ± 0.2b

10-hour

20.7 ± 1.2b

13.8 ± 1.2a

14.6 ± 0.6a

14.5 ± 0.3a

100-hour

22.7 ± 1.6b

15.6 ± 2.2a

16.7 ± 0.7a

15.2 ± 0.9a

1000-hour

24.1 ± 0.6b

18.4 ± 2.7a

19.8 ± 2.0a

18.2 ± 0.3a

Shrub mortality (%)

100 %

<5 %

<5 %

81 %

Fire behavior

Flame length (m)

5 to 11

4 to 7

3 to 6

4 to 7

Burn duration (minutes)

6 to 12

3 to 5

3 to 5

4 to 9

Surface soil temp. (°C)

961 ± 42

Not detected

680 ± 76

924 ± 103

2 cm deep soil temp. (°C)

201 ± 22

Not detected

Not detected

208 ± 57

Plot area burned (%)

95 to 100

15 to 20

15 to 20

20 to 28

Max. juniper fuel consumed

1000-hr

1-hr

10-hr

1000-hr