Table 2 Reference fire return intervals (FRIs) of pre-Euro-American settlement fire regimes (PFRs) considered in this analysis, and sources (citations on following pages, asterisks denote studies conducted wholly or mostly outside of California). Mean minimum and mean maximum are rounded to the nearest multiple of 5.

Aspen

Populus tremuloides Michx, various conifers

19

20

10

90

1–7

Big sagebrush

Artemisia tridentata Nutt., Purshia tridentata (Pursh.) DC., Chrysothamnus spp.

35

41

15

85

2, 4, 7–22, 281–283

Bigcone Douglas-fir

Pseudotsuga macrocarpa (Vasey) Mayr, Quercus chrysolepis Liebm.

31

30

5

95

2, 23–26

Black and low sagebrush¹

Artemisia nova A. Nelson, A. arbuscula Nutt.

66

53

35

115

2, 4, 12, 13, 21, 22, 27–31, 284

California juniper

Juniperus occidentalis Hook.

83

77

5

335

2, 13, 15, 18, 32

Chaparral and serotinous conifers

Adenostoma spp., Arctostaphylos spp., Ceanothus spp., Quercus berberidifolia Liebm., other shrubs; Pinus attenuata Lemmon, P. muricata D. Don, Cupressus spp., other serotinous conifers

55

59

30

90

2, 33–72

Coastal fir¹

Abies grandis (Douglas ex D. Don) Lindl., Pseudotsuga menziesii (Mirb.) Franco

99

NA²

90

435

73–84

Coastal sage scrub

Artemisia californica Less., Baccharis pilularis DC., Eriogonum fasciculatum Benth., Salvia spp., etc.

76

100

20

120

2, 25, 44, 47, 48, 71, 85–94

Curl-leaf mountain mahogany¹

Cercocarpus ledifolius Nutt.

52

62

30

130

2, 4, 7, 14, 16, 18, 22, 95–98

Desert mixed shrub

Atriplex spp., Sarcobatus vermiculatus (Hook.) Torr., Larrea tridentata (DC.) Coville, Coleogyne ramosissima Torr., Prosopis spp., Yucca spp., Ephedra spp., Opuntia spp., etc.

610

610

120

1440

2, 99–108

Dry mixed conifer

Pinus ponderosa, P. lambertiana Douglas, Calocedrus decurrens (Torr.) Florin, Abies concolor (Gord. & Glend.) Lindl ex Hildebr., Quercus kelloggii Newberry

11

9

5

50

3, 6, 24, 68, 70, 71, 109–140

Fire sensitive spruce or fir¹

Abies amabilis (Douglas ex Louden) Douglas ex Forbes, A. bracteata, Picea engelmannii Perry ex Engelm., P. breweriana

117

93

90

250

2, 22, 44, 141–157, 278–280, 285–297

Lodgepole pine

Pinus contorta Douglas ex Louden ssp. murrayana (Balf.) Engelm.

37

36

15

290

2, 3, 5, 6, 21, 68, 70, 112, 125, 127, 132, 158–172

Mixed evergreen

Pseudotsuga menziesii, Lithocarpus densiflorus (Hook. & Arn.) Rehder, Quercus agrifolia Née, Q. chrysolepis, Umbellularia californica (Hook. & Arn.) Nutt., Arbutus menziesii Pursh, Acer macrophyllum Pursh, Taxus brevfolia Nutt.

29

13

15

80

2, 23, 44, 74, 82, 127, 173–187

Moist mixed conifer

A. concolor, Pseudotsuga menziesii, Calocedrus decurrens, Pinus ponderosa, P. lambertiana, P. contorta ssp. murrayana, Sequoiadendron giganteum (Lindl.) J. Buchholz

16

12

5

80

2, 3, 6, 68, 70, 71, 98, 110–113, 116, 117, 119, 121–123, 125, 127–130, 132, 133, 136, 145, 147, 164, 168, 170, 183, 187–209

Montane chaparral

Arctostaphylos spp., Ceanothus spp., Quercus vaccinifolia Kellogg, Prunus ilicifolia (Nutt. Ex Hook. & Arn) D. Dietr., Chrysolepis sempervirens (Kellogg) Hjelmquist, other shrubs

27

24

15

50

2, 33, 58, 68, 209–211

Oak woodland

Quercus douglasii Hook & Arn, Q. lobata Née, Q. wislizenii A. DC., Pinus sabiniana Douglas ex Douglas

12

12

5

45

2, 44, 68, 127, 186, 212–225

Pinyonjuniper¹

Pinus monophylla Torr. & Frém., Juniperus spp.,

151

94

50

250

2, 14, 16, 22, 71, 89, 226–233

Port Orford cedar

Chamaecyparis lawsoniana (A. Murray) Parl.

30

16

10

160

2, 98, 144, 147, 168, 173, 177, 187, 188, 205, 234–237

Red fir

Abies magnifica A. Murray, A. concolor, Pinus montícola Douglas ex D. Don, P. murrayana

40

33

15

130

2, 3, 6, 68, 110, 112, 119, 127, 132, 134, 162, 164, 168–170, 172, 181, 187, 238–248

Redwood

Sequoia sempervirens (Lamb. Ex D. Don) Endl.

23

15

10

170

2, 44, 74, 82, 174, 178, 179, 182, 186, 249–257

Semi-desert chaparral

Adenostoma fasciculatum Hook. & Arn., Arctostaphylos spp., Cercocarpus betuloides Nutt., Eriogonum fasciculatum Benth., Purshia glandulosa Curran, Fremontodendon californicum (Torr.) Coville, Quercus john-tuckeri Nixon & C.H. Mull, etc.

65

65

50

115

2, 258–261

Shore pine¹

Pinus contorta Douglas ex Louden ssp. contorta

250

NA²

190

1025

78, 262, 277

Silver sagebrush

Artemisia cana Pursh

35

31

15

65

2, 10, 58, 263, 264, 298

Spruce-hemlock¹

Picea sitchensis (Bong.) Carrière, Tsuga heterophylla (Raf.) Sarg., Pseudotsuga menziesii

275

NA²

180

550

75, 77, 80, 265–269

Subalpine forest

Tsuga mertensiana (Bong.) Carrière, Pinus albicaulis Engelm., P. monticola, P. contorta ssp. murrayana, P. flexilis James, P. balfouriana Balf., P. longaeva D.K. Bailey, Abies magnifica

133

132

100

420

2, 68, 98, 112, 143, 164, 165, 168, 172, 187, 199, 270–272

Western white pine

Pinus monticola

50

42

15

370

2, 6, 98, 112, 119, 127, 134, 147, 164, 166, 168–170, 172, 199, 245, 257, 273

Yellow pine

Pinus ponderosa, P. jeffreyi, P. washoensis H. Mason & Stockw., P. lambertiana, Quercus kelloggii

11

7

5

40

2, 3, 14, 21, 68, 70, 71, 113, 116, 117, 119, 127, 131, 132, 134, 165, 169, 189, 200, 224, 263, 274–276