Ecological Archives E087-024-A2

M. A. Krawchuk, S. G. Cumming, M. D. Flannigan, and R. W. Wein. 2006. Biotic and abiotic regulation of lightning fire initiation in the mixedwood boreal forest. Ecology 87:458–468.

Appendix B. Summary of variables used in logistic regression models.


Weather (fuel moisture)

   

Index

Classification

Range (mean)

 

FFMCDAYS

number of days per voxel above threshold FFMC

0-44 (16)

 

DMCDAYS

number of days per voxel above threshold DMC

0-56 (14)

 

SSR

regional annual seasonal severity rating of fire weather

0.8-1.4 (1.06)

 

LDAYS

number of days with lightning per voxel

0-29 (3)

 

LCOUNT

sum of lightning strikes per voxel

0-332 (37)

 

FFMCJWL

joint FFMC – lightning index

0-12 (2)

 

DMCJWL

joint DMC – lightning index

0-13 (2)

 

ISIJWL

joint ISI – lightning index

0-15 (3)

 

wFFMCJWL

weighted FFMCJWL

0-10.4 (1.4)

 

wDMCJWL

weighted DMCJWL

0-12 (1.5)

 

Geography

     

ELEV

Elevation at the centroid of each landscape

227-1019 m

 

NORTH

UTM at centroid of landscape

6 100 565 – 6 428 588


Forest composition

 

Landscape

Regional


Stand cover type

Forest classification

Range (median)§

Proportion(found)


deciduous (AL)

deciduous canopy dominance and less than 25% canopy closure, up to 50% conifer by volume

0-1500 (27)

0.01 (71%)

deciduous (AH)

deciduous canopy dominance and greater than 25% canopy closure, up to 50% conifer by volume

0-8400 (2200)

0.27 (99%)

white spruce (SW)

white spruce canopy dominance and up to 50% other species by volume

0-3600 (360)

0.06 (90%)

jack pine (PJ)

jack pine canopy dominance

0-6300 (460)

0.09 (95%)

black spruce (SB)

black spruce canopy dominance

0-6400 (540)

0.11 (95%)

open (O)

low density scrub and all wetland types (not including water bodies)

100-9200 (3300)

0.38 (100%)

burned (B)

burned at the time of inventory

0-9300 (0)

0.06 (35%)

various||

burned or logged after inventory with unknown pre-disturbance cover type, cut at time of inventory, or unknown date of disturbance

0-7300 (0)

0.02


Mean values from all 946 sample landscapes were used in regional proportions of forest composition since some values changed slightly over the study period as a result of disturbances.

The percentage of landscapes wherein the forest type is found.

§ Area in ha per landscape.

|| Not included in analyses due to small sample sizes.



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