Table 2 Burn date, weather, soil and fuel moisture, and fire behavior during prescribed burning for the burn treatments at the NGBER site, NGBER, 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 21

0 to 5.5

11.5 to 13.5

19 to 23

Relative humidity (%)

13 to 15

50 to 78

49 to 52

19 to 20

Wind speed (km hr⁻¹),

6 to 14, NE

Calm to 12, NE

2 to 12, NE

9 to 14, W

Sky

Clear

Clear

Clear

Clear

Soil water content

Slash

9.8 ± 0.9a

30.2 ± 1.1c

33.1 ± 4.6c

22.1 ± 1.5b

Canopy

7.2 ± 0.2a

28.0 ± 0.8c

32.7 ± 3.1c

15.2 ± 1.3b

Interspace

8.7 ± 0.2a

27.0 ± 0.8c

28.6 ± 1.0c

13.4 ± 1.1b

Fuel moisture (%)

Herbaceous

3.9 ± 0.3a

33.2 ± 0.7b

62.4 ± 12.3c

57.3 ± 14.3c

Juniper needles

Suspended ²

3.8 ± 0.2a

24.8 ± 1.6c

18.1 ± 0.6b

3.8 ± 0.2a

Ground surface ³

8.5 ± 1.3a

80.0 ± 11.1b

97.5 ± 9.7b

8.5 ± 1.3a

Canopy mat

14.2 ± 1.3a

65.3 ± 8.1b

125.6 ± 15.4c

52.6 ± 12.7b

Cut juniper roundwood ⁴

1-hour

8.2 ± 0.3a

14.2 ± 1.3b

13.2 ± 1.2b

10.3 ± 1.2a

10-hour

13.7 ± 0.6a

16.4 ± 1.6ab

15.1 ± 1.8ab

17.1 ± 2.9b

100-hour

14.5 ± 1.3a

18.0 ± 2.4b

20.6 ± 3.7b

19.6 ± 2.2b

1000-hour

18.1 ± 0.7

20.4 ± 1.3

17.5 ± 5.2

17.3 ± 3.2

Shrub mortality (%)

100 %

<5 %

9 %

82 %

Fire behavior

Flame length (m)

8 to 10

3 to 5

3 to 7

5 to 10

Burn duration (minutes)

6 to 12

2 to 4

3 to 6

9 to 15

Surface soil temp. (°C)

977 ± 67

Not detected

593 ± 31

864 ± 89

2 cm deep soil temp. (°C)

204 ± 30

Not detected

Not detected

220 ± 36

Plot area burned (%)

100

12 to 18

12 to 19

18 to 25

Max. juniper fuel consumed

1000-hr

1-hr

10-hr

1000-hr