Dryopteris spp.


Table of Contents


INTRODUCTORY


Photo by Virginia Kline, University of Wisconsin Arboretum

AUTHORSHIP AND CITATION:
Munger, Gregory T. 2007. Dryopteris spp. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].

FEIS ABBREVIATION:
DRYSPP
DRYCAM
DRYCAR
DRYEXP
DRYINT

SYNONYMS:
Dryopteris assimilis S. Walker [68,72]
= Dryopteris expansa (C. Presl) Fraser-Jenkins & Jermy

Dryopteris dilitata (Hoffm.) A. Gray [35,67]
= Dryopteris expansa (C. Presl) Fraser-Jenkins & Jermy

Dryopteris spinulosa (Muell.) Watt [54,127,138,152]
= Dryopteris carthusiana (Vill.) H. P. Fuchs

Dryopteris spinulosa (Muell.) Watt var. americana (Fisch.) Fern. [67,138]
= Dryopteris campyloptera (Kunze) Clarkson

Dryopteris spinulosa (Muell.) Watt var. intermedia (Muhl.) Underw. [138]
= Dryopteris intermedia (Muhl.) Gray

NRCS PLANT CODE [165]:
DRYOP
DRCA3
DRCA11
DREX2
DRIN5

COMMON NAMES:
mountain woodfern
spinulose woodfern
spreading woodfern
fancy fern

TAXONOMY:
The scientific genus name for woodfern is Dryopteris Adans. (Dryopteridaceae) [47,72]. The woodferns are grouped in Section Lophodium (Newman) C. Chr. ex H. It [68]. This review summarizes information on the following woodfern species:

Dryopteris campyloptera (Kunze) Clarkson [24,47,52,68,72,76,127,152,173], mountain woodfern
      (originated from a cross of D. expansa D. intermedia [68])
Dryopteris carthusiana (Vill.) H. P. Fuchs [24,35,47,52,68,72,79,96,173], spinulose woodfern
Dryopteris expansa (C. Presl) Fraser-Jenkins & Jermy [24,36,47,52,65,68,72,126,171,172], spreading woodfern
Dryopteris intermedia (Muell.) A. Gray [24,47,52,67,68,72,76,96,127,152,173], fancy fern

When discussing characteristics typical (or likely to be typical) of all 4 of the above taxa, this review refers to them collectively as woodfern(s). When referring to individual taxa, the common names listed above are used.

In addition to the synonyms listed above, other names for woodferns are sometimes encountered in the literature. Dryopteris austriaca has been used as a synonym for both D. expansa (e.g., [68]) and D. campyloptera (e.g., [72]). For the purposes of this review, when species-relevant information is encountered that is linked with Dryopteris austriaca, the name D. austriaca is interpreted as a synonym for D. expansa. Dryopteris spinulosa may refer to one or more woodferns in some references encountered in the literature. When species-relevant information is encountered for D. spinulosa, this review assumes D. spinulosa is a synonym for D. carthusiana.

A number of hybrids have been identified, including the following:

Dryopteris benedictii Wherry (Dryopteris carthusiana D. clintoniana) [52]
Dryopteris boottii (Tuckerm.) Underw. (Dryopteris intermedia D. cristata) [52,76,96,152,173]
Dryopteris dowellii (Farw.) Wherry (Dryopteris clintoniana D. intermedia) [52]
Dryopteris pittsfordensis Slosson (Dryopteris carthusiana D. marginalis)
Dryopteris separabilis Small (Dryopteris celsa D. intermedia) [52,173]
Dryopteris triploidea Wherry (Dryopteris intermedia D. carthusiana) [52,96,173]
Dryopteris uliginosa Druce (Dryopteris carthusiana D. cristata) [52,173]

A review by Xiang and others [174] indicates Dryopteris triploidea is commonly found where one or both parents occur, and in some locations may outnumber the parent species.

There is some indication that many hybrids are sterile [52,127,173].

LIFE FORM:
Fern or fern ally

FEDERAL LEGAL STATUS:
No special status

OTHER STATUS:
Information on state-level protected status of plants in the United States is available at Plants Database.

DISTRIBUTION AND OCCURRENCE

SPECIES: Dryopteris spp.
GENERAL DISTRIBUTION:
Woodferns are native to North America [68,72]. Globally, spinulose woodfern and spreading woodfern distributions are circumpolar, or nearly so [24,52,68,138]. Flora of North America provides distribution maps of woodferns.

Mountain woodfern is distributed from Labrador and Newfoundland to southern Quebec, western Massachusetts, New York, Pennsylvania, and Michigan, and south along the Appalachian mountains to North Carolina, South Carolina, Tennessee, and Alabama [24,52,72,125,127,152,173]. Several sources indicate that mountain woodfern also occurs in some areas of Alaska, British Columbia, Washington, and Oregon [61,106,107,138,161], and perhaps Idaho and Montana [61]. Roland and Smith [138] indicate that mountain woodfern is distributed from Greenland to Alaska. However, Hoshizaki and Wilson [68] indicate mountain woodfern is native to eastern North America. Confusion about mountain woodfern distribution may stem from the use of Dryopteris austriaca as a synonym (see Taxonomy).

Spinulose woodfern may be found from Labrador west to Alaska and south to South Carolina, Alabama, Arkansas, Nebraska, Montana, Idaho, and Oregon [24,35,52,54,72,79,96,138,173].

In northeastern North America, spreading woodfern distribution extends from southern Greenland to Labrador and northern Newfoundland, Quebec, the Lake Superior Basin of Ontario, northern Michigan, Wisconsin, and northwestern Minnesota [24,52,72]. In western North America it is found predominantly in coastal areas from the Kenai Peninsula of Alaska south to central California [65,126]. Spreading woodfern also occurs in Yukon, Northwest Territories, interior British Columbia, western Alberta, Montana, Idaho, and northeastern Washington [24,72,80], and rarely in Wyoming and Colorado [36,72,171,172].

Fancy fern occurs from Newfoundland west to Minnesota and south to Missouri, Tennessee, Alabama, Georgia, and South Carolina [24,52,72,127,138,173].

Comprehensive surveys examining the presence or absence of woodferns within the following biogeographic vegetation schemes are not available. These lists represent a "best estimate" of woodfern occurrence based on information obtained from floras and other literature, herbaria samples, and confirmed observations.

ECOSYSTEMS [51]:
FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES12 Longleaf-slash pine
FRES13 Loblolly-shortleaf pine
FRES14 Oak-pine
FRES15 Oak-hickory
FRES16 Oak-gum-cypress
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES26 Lodgepole pine
FRES27 Redwood

STATES/PROVINCES: (key to state/province abbreviations)
UNITED STATES

AL AK AR CA CO CT DE GA ID IL
IN IA KY ME MD MA MI MN MO MT
NE NH NJ NY NC ND OH OR PA RI
SC SD TN VT VA WA WV WI WY DC

CANADA
AB BC MB NB NF NT NS ON PE PQ
SK YK

BLM PHYSIOGRAPHIC REGIONS [17]:
1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
8 Northern Rocky Mountains
9 Middle Rocky Mountains
11 Southern Rocky Mountains

KUCHLER [75] PLANT ASSOCIATIONS:
K001 Spruce-cedar-hemlock forest
K002 Cedar-hemlock-Douglas-fir forest
K003 Silver fir-Douglas-fir forest
K004 Fir-hemlock forest
K005 Mixed conifer forest
K006 Redwood forest
K008 Lodgepole pine-subalpine forest
K013 Cedar-hemlock-pine forest
K015 Western spruce-fir forest
K025 Alder-ash forest
K028 Mosaic of K002 and K026
K093 Great Lakes spruce-fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce-fir forest
K097 Southeastern spruce-fir forest
K098 Northern floodplain forest
K099 Maple-basswood forest
K101 Elm-ash forest
K102 Beech-maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K107 Northern hardwoods-fir forest
K108 Northern hardwoods-spruce forest
K109 Transition between K104 and K106
K113 Southern floodplain forest

SAF COVER TYPES [42]:
1 Jack pine
5 Balsam fir
12 Black spruce
13 Black spruce-tamarack
15 Red pine
16 Aspen
17 Pin cherry
18 Paper birch
19 Gray birch-red maple
20 White pine-northern red oak-red maple
21 Eastern white pine
22 White pine-hemlock
23 Eastern hemlock
24 Hemlock-yellow birch
25 Sugar maple-beech-yellow birch
26 Sugar maple-basswood
27 Sugar maple
28 Black cherry-maple
30 Red spruce-yellow birch
31 Red spruce-sugar maple-beech
32 Red spruce
33 Red spruce-balsam fir
34 Red spruce-Fraser fir
35 Paper birch-red spruce-balsam fir
37 Northern white-cedar
38 Tamarack
39 Black ash-American elm-red maple
52 White oak-black oak-northern red oak
53 White oak
55 Northern red oak
57 Yellow-poplar
58 Yellow-poplar-eastern hemlock
59 Yellow-poplar-white oak-northern red oak
60 Beech-sugar maple
61 River birch-sycamore
62 Silver maple-American elm
63 Cottonwood
88 Willow oak-water oak-diamondleaf (laurel) oak
91 Swamp chestnut oak-cherrybark oak
93 Sugarberry-American elm-green ash
95 Black willow
96 Overcup oak-water hickory
100 Pondcypress
101 Baldcypress
102 Baldcypress-tupelo
107 White spruce
108 Red maple
110 Black oak
201 White spruce
202 White spruce-paper birch
203 Balsam poplar
204 Black spruce
205 Mountain hemlock
206 Engelmann spruce-subalpine fir
217 Aspen
218 Lodgepole pine
221 Red alder
222 Black cottonwood-willow
223 Sitka spruce
224 Western hemlock
225 Western hemlock-Sitka spruce
226 Coastal true fir-hemlock
227 Western redcedar-western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir-western hemlock
232 Redwood
235 Cottonwood-willow
243 Sierra Nevada mixed conifer
251 White spruce-aspen
252 Paper birch
253 Black spruce-white spruce
254 Black spruce-paper birch

SRM (RANGELAND) COVER TYPES [143]:
901 Alder
902 Alpine herb
904 Black spruce-lichen
914 Mesic sedge-grass-herb meadow tundra
917 Tall shrub swamp
920 White spruce-paper birch
921 Willow

HABITAT TYPES AND PLANT COMMUNITIES:
Vegetation classifications describing plant communities where woodferns are dominant species are listed below.

Alaska: North Carolina:
Virginia:
Wisconsin:
Great Smoky Mountains National Park:
Isle Royale National Park, Michigan:
Northeastern US and adjacent Canada:
Northern and Central Appalachians:
Southern Appalachians:
British Columbia: Newfoundland:

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Dryopteris spp.

 

Photo by Virginia Kline, University of Wisconsin Arboretum
GENERAL BOTANICAL CHARACTERISTICS:
This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g., [24,35,52,68,79,127,152,171,172,173]).

Woodferns are a group of closely-related terrestrial ferns with relatively large, 2-to 4-pinnately branched fronds forming a widely arching crown, arising from a short, stout rhizome [24,52,54,57,68,79,127]. Rhizomes are variously described as horizontal, short-creeping, ascending, or erect [24,52,54,57,68,127]. Woodferns range from deciduous to evergreen (see Seasonal Development). Tiny, roundish spores are produced in sori on the undersides of the fronds [24,54,57,79,126,134].

Reported woodfern frond sizes
Overall frond length Blade length Blade width Stipe length
Mountain woodfern 24 to 35 inches (60-90 cm) [24,68] 12 to 24 inches (30-60 cm) [52,127,152] 8 to 16 inches (20-40 cm) [52,127,152] Less than or equal to the blade [24,52]
Spinulose woodfern 12 to 39 inches (30-100 cm) [24,54,68,79] 8 to 24 inches (20-60 cm) [24,52,54,79] 2 to 12 inches (6-30 cm) [24,52,54,79] Mostly a quarter to a third as long as the blade [52]
Spreading woodfern 10 to 39 inches (25-100 cm) [24,57,60,65,68,126,149] Up to 28 inches (70 cm) [57,65,78] 4 to 16 inches (10-40 cm) [57,65,78] Half to fully as long as the blade [24,52]
Fancy fern 14 to 28 inches (35-70 cm) [24,68] 8 to 20 inches (20-50 cm) [52,127,152] 4 to 25 inches (10-25 cm) [52,127,152] 4 to 12 inches (10-30 cm) [52], or a quarter to a third the length of the frond [24]

Alaback [3] indicated that spreading woodfern frond size varies with successional stage in southeastern Alaska forests and is presumably related to light availability. In the early postdisturbance stage, where light availability is usually greatest, frond length often exceeds 3.3 to 3.9 feet (1.0-1.2 m) compared to 0.3 to 1 foot (0.1-0.3 m) in darker, mature forests [3].

RAUNKIAER [129] LIFE FORM:
Geophyte

REGENERATION PROCESSES:
Woodferns reproduce both by spores and vegetative means. The American Fern Society provides information on fern life cycles and regeneration processes.

Breeding system: Woodferns produce male-only plants, female-only plants, and bisexual plants. Although sexual expression is variable, woodferns are apparently capable of selfing and outcrossing [28].

Spore production: Spreading woodfern spores [57,126,137], and presumably spores of all woodferns [5], are produced along veins on the lower surface of the frond blades. One study estimated spinulose woodfern spore production at 10,000 to 100,000/frond [43], and another at 138,240/plant [121]. In general, a single individual of most fern species can produce millions, often billions, of spores/plant, although very few result in successful reproduction [5].

Spore dispersal: As of 2007, there was very little published information about woodfern spore dispersal. Woodfern occurrence is probably not dispersal limited. A review by Bellemare and others [15] suggests that fancy fern spores are dispersed widely by wind. Propagule banking studies (see below) show that spores may be found in soil where few to no woodfern plants currently grow, suggesting that wind dispersal may lead to colonization of new habitats.

Propagule banking: Several studies have demonstrated that woodferns may accumulate propagule banks. Fancy fern spores were present in soil samples collected from 6 Catskill Mountains eastern hemlock stands at densities of 283 to 5546/m. Fancy ferns were among the dominant herbaceous species present in sample plots [175].

Woodfern spores may be found in soil even where woodfern plants are sparse or absent. In a Norwegian study, percent constancy of woodfern spores in the propagule bank (52%) was significantly greater (P<0.001) than that of woodfern plants in the corresponding aboveground vegetation plots (2%) [139]. A study in east-central New York consistently found viable spinulose woodfern spores in the soil propagule bank across a range of sites, including sites that had no existing spinulose woodfern plants [13]. It was not clear in either study if spores found in uncolonized plots were dispersed from nearby populations, or if soil-stored spores came from rare or extirpated on-site plants.

Sexual regeneration/plant establishment: When fern spores encounter favorable conditions they produce tiny gametophytes by cell division. Then the gametophyes, again given favorable conditions, generate the sporophyte via sexual reproduction [5].

As of this writing (2007), information describing favorable substrates for woodfern establishment and growth was scarce and perhaps conflicting. It is possible that there are differences in establishment substrate affinities among woodfern species. Fancy fern was significantly more abundant (P<0.01) on decaying logs than on the forest floor of a northern hardwoods site in Adirondack State Park, New York [91], indicating that establishment may be enhanced by coarse woody debris. Several sources assert that spreading woodfern grows best on decaying wood [73,78] or in organic soil horizons [71]. However, a study of postdisturbance forest understory dynamics led to speculation that spinulose woodfern establishes best on bare mineral soil [119].

Woodfern establishment may also be influenced by competing vegetation. A laboratory experiment demonstrated a possible reciprocal allelopathic effect between fancy fern and cinnamon fern (Osmunda cinnamomea) gametophytes in culture [123], although the importance of this effect in the field was not discussed.

Asexual regeneration: Spinulose woodfern spreads vegetatively by rhizomes [7,144]. Other woodferns also have rhizomes [24,52,57,68,126,127,137], which presumably aid in their spread as well. As of 2007, published information describing the biology of vegetative spread in woodferns was lacking.

There is some indication that asexual regeneration is ecologically important, at least in some woodfern populations. A review by Archibold [7] indicates that in spinulose woodfern, vegetative reproduction by rhizomes is more common than sexual reproduction by spores. A study in a north-central New Hampshire northern hardwood forest indicated that nearly all spinulose woodfern plants sampled during 3 growing seasons originated from preexisting rhizomes rather than establishment of new genets [69].

SITE CHARACTERISTICS:
The following descriptions of site characteristics indicate conditions under which woodferns can be found in North America. Unless specifically indicated, these descriptions do not strictly delineate site requirements, and woodferns may not be limited to these types of sites.

Habitat: Commonly described mountain woodfern habitats in eastern North America include cool, moist, rich, often rocky forests and woodlands [24,52,127,138,173]. Mountain woodfern is frequently mentioned in association with spruce (Picea spp.) and/or fir (Abies spp.) habitats in this region [76,101,105,130,133,152]. Although woodfern habitats are most often described as closed-canopy forests, mountain woodfern also occurs in open, subalpine glades in the balsam fir zone of the White Mountains, New Hampshire [130].

Spinulose woodfern habitats are commonly described as usually moist or wet woodlands, forests, thickets [11,24,31,52,68,90,96,127,138,173], swamps, bogs [11,52,138,142,173], or riparian areas [24,25,54,68,79]. Spinulose woodfern has also been mentioned in association with such diverse habitats as "snowbank communities" in the alpine zone of the Presidential Range, New Hampshire [18], and a baldcypress (Taxodium distichum) swamp in South Carolina [87].

Several sources provide more specific habitat information for spinulose woodfern. Spinulose woodfern was found in high marsh sections of old oxbows in western Massachusetts, where soil was perpetually wet but typically lacked standing water during latter stages of the growing season [66]. Spinulose woodfern was closely associated with basin wetland forests but not with floodplain forests in southeastern Wisconsin [39]. An analysis of understory vegetation in northwestern Quebec boreal forests determined that spinulose woodfern occurrence was significantly greater in jack pine habitats compared with quaking aspen, paper birch, or white spruce-balsam fir habitats (P=0.033) [81]. Spinulose woodfern cover was significantly greater in southwestern Alberta Rocky Mountain lodgepole pine (Pinus contorta var. latifolia) stands with site index (height at 50 years age) ≥62 feet (19 m) compared with all lower site index stands (P<0.05), indicating spinulose woodfern may be more prominent on the most productive Rocky Mountain lodgepole pine-dominated sites in the northern Rocky Mountains [155].

Spreading woodfern habitats encompass a diverse range of communities in western North America. Spreading woodfern is commonly associated with cool, moist forests, woodlands, thickets [24,35,36,52,65,126,137,149], floodplains [48], and streambanks [65,137]. These habitats may be shaded or in openings [65,126]. They range from coastal to montane in the Pacific Northwest [57,126] and subalpine to timberline in the Rocky Mountains [60,77,78,171,172]. Spreading woodfern has been associated with climax coastal rainforests in British Columbia [82], a marl fen community in northeastern Washington [80], sphagnum (Sphagnum spp.) bogs in Glacier National Park, northwestern Montana [149], and scree slopes in the Pacific Northwest [126]. In Alaska, spreading woodfern has been noted in alpine meadows [137], in rock recesses and talus on nunataks of the Juneau Ice Field [64], and above timberline, in and above the alder (Alnus spp.) zone in the Talkeetna Mountains [95]. Although it does occur in northeastern North America (see Distribution and Occurrence ), as of 2007 there were no published descriptions of spreading woodfern habitats in this region.

Fancy fern habitats in eastern North America are generally forested or otherwise shaded (e.g., [34,41,52,118,127,152,173] and sometimes rocky [96,127,138,152,173].

Soils: Soils in Appalachian Mountain habitats where mountain woodfern is common are often described as shallow, rocky, acidic, nutrient-poor, and organic-rich [46,101,104,105,142].

Spinulose woodfern grows on a variety of soil types in North America. A review of site conditions in Canada indicates that it is primarily an acidophilic species and a good indicator of medium-nutrient soils. Spinulose woodfern is characteristic of poorly drained, alluvial or lacustrine sites in the Lesser Slave Lake area of north-central Alberta; is associated with seepage areas in northern white-cedar (Thuja occidentalis) swamps having well-decomposed peaty soils in southern boreal wetland habitats in Ontario; is abundant on moderately fertile, wet, organic soils in relatively open, hardwood-eastern hemlock forest ecosystems of the Great Lakes-St Lawrence Forest Region of Ontario; and is characteristic of mesic sites associated with glaciated knobs and moderately deep till slopes in the northern hardwood forests of Quebec [134]. An analysis of understory vegetation in northwestern Quebec boreal forests determined that spinulose woodfern occurrence was significantly greater on clay surface deposits, compared with till deposits (P=0.015) [81]. Other descriptions of soils associated with spinulose woodfern include

Soils where spreading woodfern is found range from poorly drained [12] to well drained [167]. Taylor [157] suggested that in forests of southeastern Alaska, spreading woodfern has an affinity for soils with pH ranging from 5.0 to 6.0. A study of environmental gradients in the California redwood region showed that spreading woodfern distribution was associated with the most nutrient-rich sites [170]. Other descriptions of soils associated with spreading woodfern include:

Fancy fern is commonly associated with strongly acidic soils [34,76,102,103,111,124,142], ranging from excessively well drained to imperfectly drained [76,105,124]. It is often found growing on decaying wood in southwestern Ontario [21]. Other descriptions of soils associated with fancy fern include:

Moisture: Woodferns generally have a strong affinity for moist sites.

Mountain woodfern is found on sites in the southern Appalachians ranging from wet to dry-mesic [101,104,142]. In red spruce and red spruce-Fraser fir subalpine forests on Mount Rogers, Virginia, relative importance of mountain woodfern is greatest on mesic sites [133].

Most evidence suggests that spinulose woodfern also has a strong affinity for moist habitats. It is found in seasonally flooded habitats where soils are perpetually moist [39,66,90]. Two studies in the northern Great Lakes region indicated that spinulose woodfern abundance was strongly associated with moisture [88,89]. In flood-prone habitats spinulose woodfern grows mainly on hummocks rather than in hollows where there is standing water [31,70]. Although Mohlenbrock [96] indicates that it is rarely found in dry habitats in Illinois, Peet [122] indicated that spinulose woodfern was "primarily confined to drier microsites" in an eastern white pine-dominated forest in Itasca State Park, Minnesota.

Spreading woodfern is also strongly associated with moist habitats. It is an indicator of moist sites in the western hemlock zone of the Gifford Pinchot National Forest, Washington [162]. It is found on moist, floodplain soils in south-central Alaska subject to periodic flooding [48] and on mesic to subhygric sites in coastal British Columbia western redcedar-Douglas-fir-western hemlock forests [110]. Spreading woodfern is a common understory component in wetter areas of old-growth Douglas-fir-western hemlock forests northwestern Oregon [147]. Lackschewitz [78] stated that spreading woodfern "requires more moisture than most other ferns" of western Montana. A study of environmental gradients in the California Coastal Redwood Region showed spreading woodfern distribution is associated with very moist sites (average minimum available moisture=74.5%) [170]. Spreading woodfern is found on fresh to very moist (groundwater table between 1-2 feet (30-60 cm)) soils in coastal British Columbia [73].

Fancy fern may be less strongly associated with moist sites than other woodferns. It is found on mesic sites in northern lower Michigan northern hardwood forests [136]. It is a characteristic herb of mesic to submesic sites in central Appalachian northern hardwood forests [103] and a dominant herb on mesic to dry-mesic sites in eastern hemlock-northern hardwoods forests of the northern and central Appalachians [111]. Oosting [118] suggested that fancy fern requires shade and moisture in North Carolina Piedmont habitats.

Elevation: The following table lists elevational ranges where woodferns occur in western North America. These examples are not necessarily elevational limits to woodfern distribution.

Location Elevation
Mountain Woodfern
western North Carolina >6,000 feet (1,800 m) [142]
southwestern Virginia >5,400 feet (1,700 m) [46]
West Virginia rarely, if ever <4,000 feet (1,200 m) [152]
Adirondacks mostly >2,500 feet (760 m); up to 4,736 feet (1,444 m) [76]
Balsam Mountains, southwestern Virginia 5,220 to 5,699 feet (1,591-1,737 m)
Great Smoky Mountains National Park 5,551 to 6,299 feet (1,692-1,920 m) [133]
southern Appalachians >6,000 feet (1,830 m) [101]
southern Appalachians 5,500 to 6,200 feet (1,680-1,990 m) [104]
White Mountains, New Hampshire 4,000 to 4,760 feet (1,220-1,450 m) [130]
Spinulose Woodfern
northern New Hampshire 5,300 to 6,100 feet (1,600-1,900 m) [18]
Great Smoky Mountain National Park To 6,500 feet (2,000 m) [29]
Isle Royale National Park <650 feet (200 m) ([109] and references therein)
Spreading Woodfern
California mostly <1,600 feet (500 m), except (4,300 feet (1,300 m)) on the Modoc Plateau [65]
coastal British Columbia 0 to 2,100 feet (0-650 m) [110]
Great Smoky Mountains National Park 5,450 to 6,450 feet (1,660-1,970 m)
Juneau Ice Field, southeastern Alaska 3,800 to 4,800 feet (1,200-1,500 m) [64]
southern Appalachians 5,751 to 5,899 feet (1,753-1,798 m) [55]
Talkeetna Mountains, south-central Alaska 2,500 to 3,000 feet (760-900 m) [95]
White Mountains National Forest, New Hampshire 2,500 to 2,750 feet (760-838 m) [117]
Fancy Fern
western North Carolina, eastern Tennessee 2,800 to 4,600 feet (850-1,400 m) [112]
northwestern Pennsylvania 1,880 to 1,920 feet (572-585 m) [124]
Virginia 3,000 to 5,200 feet (900-1,600 m) [102,103]
southwestern Ontario 1,190 to 1,220 feet (362-372 m) [21]
Adirondacks 100 to 3,532 feet (30-1,077 m) [76]
central Appalachians, Virginia 3,000 to 4,300 feet (900-1,300 m) [103]
Cheat Mountain, Pocohontas County, West Virginia 3,900 feet (1,200 m) [1]
Great Smoky Mountains National Park 5,450 feet (1,660 m)
summit of Mt Everett, western Massachusetts 2,600 feet (793 m) [98]
Nantahala National Forest, western North Carolina 3,100 to 5,200 feet (950-1,600 m) [92]
northern Appalachians 1,000 to 2,500 feet (300-760 m) [105]
southern Appalachians, Virginia >3,600 feet (1,100 m) [46]
White Mountains National Forest, New Hampshire 2,700 feet (820 m) [117]

Spreading woodfern is found from coastal to subalpine elevations in the Pacific Northwest [126] and even into the alpine zone in Alaska [137]. In the central and northern Appalachians, mountain woodfern [24] and fancy fern [152] may both be found within a wide range of elevations. In the southern Appalachians, mountain woodfern occurrence is limited to high elevations [24]. Where they cooccur in the northern and central Appalachians, fancy fern tends to be more abundant at low elevations, while mountain woodfern is comparatively more abundant in the high spruce-fir zone ([85] and references therein).

Climate: Woodferns are generally restricted to the cool, moist forests of temperate and boreal North America. Although mountain woodfern is found in high-elevation habitats where the climate is cool and wet in the Appalachians [46,101,104,142], its fronds are considered frost sensitive [76,152]. A review of site conditions in Canada indicates that spinulose woodfern occurs under boreal, cool-temperate, and cool-mesothermal climatic regimes, and its frequency increases with precipitation [134]. Spreading woodfern is found within boreal, cool-temperate, and cool-mesothermal climates in coastal British Columbia [73], and in floodplain forests in south-central Alaska, where snow cover usually remains until late May [48]. Fancy fern is found in Appalachian Mountain habitats where high rainfall and fog deposition [142] and severe winter temperatures, wind, and ice are common [103].

Minimum average January temperatures for woodfern habitats [68]
Mountain woodfern 0 F (-18 C)
Spinulose woodfern -5 F (-21 C)
Spreading woodfern -5 F (-21 C)
Fancy fern 10 F (-12 C)

SUCCESSIONAL STATUS:
Fire may be an important influence on woodfern succession and occurrence in North America. Studies illustrating the response of woodferns to fire are mostly considered in Fire Effects.

Shade tolerance: Woodferns are generally shade tolerant. Fancy fern ([20] and references therein) and spinulose woodfern [148] are characterized as shade tolerant based on physiological parameters. Spreading woodfern is also characterized as shade tolerant (e.g., [73]). Alaback [4] indicates that spreading woodfern is among the most shade-tolerant understory plants in southeastern Alaska forests. A study of environmental gradients in the California coastal redwood region showed spreading woodfern distribution was associated with shaded habitats where average light intensity was 4.7% of full sunlight [170]. As of this writing (2007), there was no published information discussing the shade tolerance of mountain woodfern. However, since mountain woodfern is found in habitats similar to those of other woodferns, it is reasonable to assume that mountain woodfern is also similarly tolerant of shade.

Succession following stand replacement: Oliver's [116] 4-stage stand development model provides a useful framework for examining how woodferns are likely to respond following stand replacement.

The first years following stand replacement (stand initiation stage) may be the least predictable in terms of woodfern response. Woodfern abundance during this period may be influenced by a number of factors including predisturbance abundance, the nature and severity of the disturbance, and the responses of associated vegetation. Most studies of forest succession following stand-replacing disturbance strongly suggest that woodfern abundance is diminished as resource competition heightens (stem exclusion stage) and then increases once more with understory replacement (understory reinitiation stage). Evidence comparing woodfern abundance in late-seral or old-growth stages with earlier stages of succession is sparse. It seems likely that woodferns persist, if not flourish, in old or late-successional forests that harbored them in previous successional stages.

Alaback [3,4] described secondary succession in western hemlock-Sitka spruce forests in southeastern Alaska, illustrating woodfern response during stand development from stand initiation to old growth. Fern populations in these forests, including spreading woodfern, generally increase in abundance directly following disturbance such as logging or large-scale windthrow, especially where tree and shrub regeneration is initially sparse [3,4]. Ferns tend to decline about 20 to 25 years after disturbance, when shrubs and tree saplings form a dense canopy. At about 50 to 60 years ferns begin to dominate the understory. During the final stages of succession, at around 250 years, understory species diversity increases, with forbs, shrubs, and tree seedlings becoming more common and ferns decreasing in importance [3].

Similar to Alaback's [3,4] characterization, a study of the effect of overstory removal on shrub and herb dynamics in a north-central New Hampshire northern hardwood forest found spinulose woodfern abundance increased slightly following disturbance. Spinulose woodfern occurred in 18.8% of sampling quadrats prior to overstory removal compared with 18.6%, 20.7%, and 23.4% during the first 3 postdisturbance years. Vegetative reproduction of existing ramets, rather than establishment of new genets, accounted for nearly all the postdisturbance spinulose woodferns sampled [69].

Other sources indicate that woodfern populations diminish in the early stages of stand development following stand-replacing disturbance. Siccama and others [144] suggested that woodferns are not a major component of early or midseral succession in the White Mountains, New Hampshire. A study at the Hubbard Brook Experimental Forest, New Hampshire, indicated that spinulose woodfern was suppressed during the first 20 years of succession in a mixed northern hardwoods-red spruce-balsam fir forest [131].

Rapidly diminished woodfern abundance following disturbance may be due, in part, to interference from other plant species. In a southern Appalachian oak-hickory forest, fancy fern was sparse but present (4% average frequency; 0.12% average cover) in undisturbed forest, but was not present in plots sampled 4 years after severe blowdown and 3 years after salvage logging. Average percent cover of groundlayer vegetation was nearly 100% in the disturbed forest compared with just over 20% in a similar nearby undisturbed forest, indicating that interference among groundlayer plants may have been much greater in the recently disturbed forest [41].

A study of changes in forest understory vegetation following stand-level windthrow in east-central Minnesota demonstrates how differences in forest type or the nature of the disturbance may result in strikingly different woodfern successional responses. In eastern white pine-dominated forest, spinulose woodfern frequency increased from little initial occurrence to 12.5 % in postdisturbance years 1 and 2, and to 34.2% by year 14. In an adjacent northern pin oak-dominated forest, very little change in spinulose woodfern frequency occurred over the 14-year study. It was speculated that the difference in spinulose woodfern postdisturbance response between forest types may have been due to differences in effects of the disturbance on overstory trees. Trees in the oak forest tended to snap off at the bole while the pines tended to uproot, creating more bare mineral soil that enhanced spinulose woodfern establishment [119].

Disturbance that kills overstory trees but leaves large numbers of intact snags and an undisturbed understory might also result in unique successional responses. Fancy fern and common woodsorrel (Oxalis montana) comprised most of the initial increase in understory cover following girdling of overstory eastern hemlock trees in southeastern New York [176].

Regardless of how rapidly succession proceeds from stand initiation to stem exclusion, woodferns may be reduced or even eliminated once the ground layer is overtopped by dense regeneration of woody species. A chronosequence study in black spruce-dominated stands in western Labrador indicated that suppression of woodfern populations may last for many years. Average spinulose woodfern cover was 1.09% in 2-year-old stands, then 0% for stand ages 18, 40, 80, and 140 years. Other herbaceous species showed a similar response. Forty- and 80-year-old stands were generally shrub-dominated, while 80- and 140-year-old stands were transitioning to dominance by tree species, mainly black spruce. It was not clear if individual spinulose woodferns in the 2-year-old stands predated the stand-initiating disturbance or if these were recently established, short-lived populations. Overall herbaceous cover remained quite low even in the 140-year-old stands, suggesting that understory reinitiation had not yet begun [145].

The time elapsed between stem exclusion and understory reinitiation may be highly variable. A long-term study of vegetation dynamics in a western Massachusetts mixed conifer-hardwood forest examined the effects of a 1938 hurricane and a subsequent salvage operation. Initial surveys indicated that the predisturbance spinulose woodfern population was greatly diminished in the first decade following the hurricane. Remeasurement of the original plots more than 50 years after the hurricane revealed that spinulose woodfern had reestablished, and understory species composition had become generally similar to prehurricane species composition [84].

Spinulose woodfern response to stand-replacing disturbance in a western Massachusetts mixed conifer-hardwood forest [84]
Year % frequency
1937 (predisturbance) 45
1940 15
1948 0
1991 23

In a study of old-growth characteristics in balsam fir forests on the Gasp Peninsula, eastern Quebec, spinulose woodfern percent frequency was directly related to stand age. Spinulose woodfern frequency in 50-year-old, second-growth stands (characterized by uniform tree cover, predominance of stems <8 inches (20 cm) DBH, high-density, and even-age structure) was 1%, compared with 8% in pristine senescent stands (characterized by the predominance of stems >8 inches (20 cm) DBH, an even-aged structure, and single or collective blowdowns in the last decade) and 21% in old-growth stands (characterized by irregular structure, an uneven-aged mosaic, and trees >90 years old) [33]. In a hybrid spruce (Picea glauca P. engelmannii) forest in central interior British Columbia, spreading woodfern was found exclusively in late-seral stands (>140 years since fire) and not in midseral (50-80 years since fire) or early-seral stands (<14 years since fire) [37].

Research in the northern mixed hardwood region of central New York comparing herb vegetation between postagricultural forest stands (64-94 years old) and adjacent old stands never cleared for agriculture suggests there may be some species-level differences in woodfern response to succession. Average fancy fern frequency was significantly greater in old forests than in postagricultural stands (P<0.05). Spinulose woodfern frequency was not significantly different between the 2 types (P>0.05), and was similar to the low levels of fancy fern in the younger forests [146].

Gap-phase succession: Woodferns commonly occur in forests where stand-replacing disturbance is relatively infrequent but periodic mortality of a single tree or small groups of trees creates canopy gaps. For example, spreading woodfern is a dominant herb of the western redcedar-coast Douglas-fir-western hemlock/western sword fern-spreading woodfern forest association, which is a closed-canopy, late-successional forest of coastal British Columbia, with a disturbance regime characterized by small-gap dynamics [110].

Two studies of gap dynamics indicate that woodferns may respond positively to canopy gap formation. In an east-central New York upland hardwood forest, spinulose woodfern was significantly more abundant in treefall gaps (P<0.05) compared with closed-canopy transects, in at least 50% of the censuses [53]. In mature eastern hemlock and deciduous forests in southeastern Ohio, spinulose woodfern cover was significantly greater (P<0.05) in canopy gaps (x=31.85%) compared with closed deciduous canopy (x=7.71%) and closed eastern hemlock canopy (x=2.98%) [128].

However, fancy fern had significantly (P<0.05) higher importance values (a function of relative cover and relative frequency) under closed canopy compared with canopy gaps of 60 to 85 m and 120 to 190 m in a mixed-conifer swamp forest in central New York [6].

Canopy gap closure rate limits the available time for plant response [27]. A chronosequence of canopy gaps in a southeastern Ohio eastern hemlock forest showed that spinulose woodfern cover peaked 3 years after gap formation [128].

Mean percent cover of spinulose woodfern under different aged canopy gaps [128]
Years since gap formation Percent cover
0 2.75
1 37.33
2 39.48
3 44.16
4 19.43
5 21.63
9 18.85

Soil disturbance microsites may also be created when trees are uprooted by windthrow. Over time these small-scale soil disturbances create a mosaic of pits and mounds, enhancing habitat heterogeneity [14]. Studies examining pit/mound topography in old-growth forests suggest a legacy effect that may influence woodfern distribution in these forests, even long after the more ephemeral influence of increased light availability associated with gap formation has waned. In an east-central New York mature sugar maple-American beech forest, spinulose woodfern seedling emergence was significantly greater in soil sampled from treefall pits compared with treefall mounds (P<0.05) [13]. On a pair of sites in a southeastern Alaska old-growth western hemlock-Sitka spruce forest, spreading woodfern importance was related to age since disturbance. On one site, undisturbed forest floor plots and old mounds (>200 years) had significantly higher spreading woodfern importance (P<0.01) than plots with young and intermediate mounds (50 and 150 years). At another site, spreading woodfern importance was significantly higher on undisturbed forest floor plots compared with windthrow mounds of all ages (age classes include mean ages of approximately 50, 150, and >200 years; P<0.01) [32]. A study in old-growth eastern hemlock-American beech forest found that fancy fern percent cover was significantly greater in old treefall pits compared with old treefall mounds and adjacent undisturbed soil (P<0.05). The treefall pits and mounds were assumed to be relatively old, since transect locations were chosen based on showing no sign of the trees that had formed the pits, and mounds and were not located beneath canopy gaps [124].

SEASONAL DEVELOPMENT:
Mountain woodfern leaves are deciduous [24,52,76,127,152], with fronds maturing in June and senescing in September and/or October in New Hampshire [85]. Spinulose woodfern is deciduous or rarely evergreen [52,54,127], and spreading woodfern is deciduous [57] or wintergreen [24,78].

Fancy fern is evergreen [52,76,127,144,152] or wintergreen [21,24], and the significance of its leaf phenology has been well studied. In the fall fancy fern leaves change from an upright to a prostrate position. This occurs due to a softening of the tissue in a 0.4- to 0.8-inch (1-2 cm) zone of the lower stipe, such that the stipe no longer supports the weight of the frond. Despite bending, the vascular tissue of the stipe remains functional and the leaves remain photosynthetically active throughout winter as long as they remain uncovered. Leaf chlorophyll levels remain high into spring. This mechanical adaptation of fancy fern leaves is thought to minimize water loss during winter [115].

Wintergreen fronds of fancy fern are capable of positive net photosynthesis throughout spring. The highest rates are achieved in early spring just after snowmelt, but positive net photosynthesis occurs even late into frond senescence [158], which occurs in early summer [85]. Tessier [158] articulated that spring carbon gain in wintergreen species such as fancy fern probably represents an important fraction of net annual energy capture. The comparatively high light environment prior to canopy leaf-out provides opportunity for carbon assimilation that is diminished in the shady summer understory. In addition to enhanced carbon capture, early spring nutrient uptake also occurs, coinciding with the highest rates of vernal photosynthesis in these wintergreen fronds [160].

Van Buskirk and Edwards [166] demonstrated the contribution of wintergreen leaves to early spring growth of fancy fern. They paired similarly-sized, proximately-located plants, and excised wintergreen leaves from one plant of each pair prior to commencement of new spring growth. Average growth rate of nonexcised plants was significantly greater than that of plants with wintergreen leaves removed (P<0.005). Within about 2 months frond biomass of intact plants was nearly twice that of excised plants [166]. Tessier and Bornn [159] used labeled 13C to demonstrate that vernally fixed carbon from old fronds is translocated to new fronds.

Woodfern spore production dates for select locations
Mountain Woodfern
Blue Ridge Mountains July-September [173]
Carolinas July-September [127]
Spinulose Woodfern
Illinois June-August [96]
eastern North Dakota, southeastern Nebraska June-September [79]
Blue Ridge Mountains June-September [173]
Carolinas June-September [127]
Great Plains June-August [54]
Canada mid- to late-summer [134]
Fancy Fern
Illinois June-August [96]
Blue Ridge Mountains June-September [173]
Carolinas June-September [127]

FIRE ECOLOGY

SPECIES: Dryopteris spp.
FIRE ECOLOGY OR ADAPTATIONS:
Fire adaptations: Although detailed studies of fire adaptations are lacking, it appears that woodferns can survive and sprout after low-severity surface fire when organic layer moisture inhibits heat damage to rhizomes. Following clearcutting and subsequent slash burning in a south-central British Columbia Engelmann spruce-subalpine fir forest, spreading woodfern postfire sprouting was observed in fall-burned plots where duff moisture was high. Postfire spreading woodfern was not observed on spring-burned plots, where duff was drier [59]. Ahlgren [2] noted survival of spinulose woodfern following severe fire (all litter, duff, and at least some, if not all humus consumed) in northeastern Minnesota. Survival occurred in moist patches where vegetative structures survived in unburned sphagnum. Chapman and Garrett [22] indicted that spinulose woodfern responds rapidly after fire via vegetative regeneration.

Although woodferns can produce many thousands of spores/plant (see Spore production), spores are thought to be widely dispersed by wind (see Spore dispersal), and propagule banking has been demonstrated, there were no published reports as of 2007 documenting postfire establishment of new woodfern gametophytes. Woodferns may colonize postfire habitats, both from on-site and off-site spores, although this is speculative.

Fire regimes: As of this writing (2007), there were no published studies specifically examining relationships between woodferns and fire regimes. Given wood ferns' affinity for cool, moist sites (see Site Characteristics), it is unlikely that they will be common on sites with frequently recurring fire, although this is speculative. With a few exceptions, the plant communities and ecosystems listed in the table below include fire return intervals that may be hundreds of years.

The following table provides fire return intervals for plant communities and ecosystems where woodferns may occur. For further information, see the FEIS review of the dominant species listed below.

Community or Ecosystem Dominant Species Fire Return Interval Range (years)
silver fir-Douglas-fir Abies amabilis-Pseudotsuga menziesii var. menziesii >200 [8]
maple-beech Acer-Fagus spp. 684-1,385 [23,169]
maple-beech-birch Acer-Fagus-Betula spp. >1,000
silver maple-American elm Acer saccharinum-Ulmus americana <5 to 200
sugar maple Acer saccharum >1,000
sugar maple-basswood Acer saccharum-Tilia americana >1,000 [169]
birch Betula spp. 80-230 [154]
sugarberry-America elm-green ash Celtis laevigata-Ulmus americana-Fraxinus pennsylvanica <35 to 200
beech-sugar maple Fagus spp.-Acer saccharum >1,000 [169]
green ash Fraxinus pennsylvanica <35 to >300 [40,169]
tamarack Larix laricina 35-200 [120]
yellow-poplar Liriodendron tulipifera <35 [169]
Great Lakes spruce-fir Picea-Abies spp. 35 to >200
northeastern spruce-fir Picea-Abies spp. 35-200 [38]
southeastern spruce-fir Picea-Abies spp. 35 to >200 [169]
Engelmann spruce-subalpine fir Picea engelmannii-Abies lasiocarpa 35 to >200 [8]
black spruce Picea mariana 35-200
conifer bog* Picea mariana-Larix laricina 35-200
red spruce* Picea rubens 35-200 [38]
jack pine Pinus banksiana <35 to 200 [23,38]
Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-340 [9,10,156]
red pine (Great Lakes region) Pinus resinosa 3-18 (x=3-10) [50]
red-white pine* (Great Lakes region) Pinus resinosa-P. strobus 3-200 [23,62,83]
eastern white pine Pinus strobus 35-200
eastern white pine-eastern hemlock Pinus strobus-Tsuga canadensis 35-200 [169]
aspen-birch Populus tremuloides-Betula papyrifera 35-200 [38,169]
quaking aspen (west of the Great Plains) Populus tremuloides 7-120 [8,56,94]
black cherry-sugar maple Prunus serotina-Acer saccharum >1,000 [169]
coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [8,97,135]
oak-gum-cypress Quercus-Nyssa-spp.-Taxodium distichum 35 to >200 [100]
white oak-black oak-northern red oak Quercus alba-Q. velutina-Q. rubra <35
northern red oak Quercus rubra 10 to <35
black oak Quercus velutina <35 [169]
redwood Sequoia sempervirens 5-200 [8,45,153]
baldcypress Taxodium distichum var. distichum 100 to >300 [100]
western redcedar-western hemlock Thuja plicata-Tsuga heterophylla >200 [8]
eastern hemlock-yellow birch Tsuga canadensis-Betula alleghaniensis 100-240 [154,169]
eastern hemlock-white pine Tsuga canadensis-Pinus strobus x=47 [23]
western hemlock-Sitka spruce Tsuga heterophylla-Picea sitchensis >200
mountain hemlock* Tsuga mertensiana 35 to >200 [8]
*fire return interval varies widely; trends in variation are noted in the species review

POSTFIRE REGENERATION STRATEGY [151]:
Rhizomatous herb, rhizome in soil
Ground residual colonizer (on-site, initial community)
Initial off-site colonizer (off-site, initial community)
Secondary colonizer (on-site or off-site spore sources)

FIRE EFFECTS

SPECIES: Dryopteris spp.
IMMEDIATE FIRE EFFECT ON PLANT:
Although detailed accounts are limited, it is likely that woodferns are usually top-killed by fire, and sometimes completely killed. Woodfern fire survival is apparently linked to organic layer moisture levels.

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:
Ahlgren [2] noted survival of spinulose woodfern following severe fire (all litter, duff, and at least some, if not all humus consumed) in northeastern Minnesota. Survival occurred in moist patches where vegetative structures survived in unburned sphagnum [2].

Hamilton and Peterson [59] studied vegetation response to clearcutting followed by slash burning of an Engelmann spruce-subalpine fir forest in south-central British Columbia. Cutting occurred over winter in 1988 and 1989, after which the site was divided into 3 treatment areas: a spring burn (7 June), a fall burn (12 September), and an unburned control. Although both burns were considered low severity, the spring burn consumed more of the forest floor (24.9%) than the fall burn (10.4 %). In the fall burn, 47.6% of the depth-of-burn pins showed no measurable duff reduction, compared with 14% of the spring burn pins. Duff moisture code was 28 for the spring burn and 8 for the fall burn, indicating much drier duff in the spring burn. Detailed burn characteristics are available in Hamilton and Peterson [59]. Spreading woodfern frequency was 36% in the unburned plots, 15% in the spring-burned plots, and 33% in the fall-burned plots prior to logging. Spreading woodfern persisted after logging in 3 unburned plots and was observed intermittently on another 3 unburned plots. The more severe spring burn eliminated spreading woodfern from all the plots in which it had occurred prior to burning. Spreading woodfern sprouted in all fall burn plots where it occurred prior to burning. In postfire year 1, spreading woodfern cover was significantly lower in burned plots (P=0.007) compared to unburned plots (P=0.007). Spreading woodfern cover was also significantly lower in spring vs. fall burn plots in postfire year 1 (P=0.05). It was concluded that spreading woodfern "is fairly sensitive to burn severity and could be eliminated by burning" [59].

PLANT RESPONSE TO FIRE:
Woodferns that survive fire sprout from rhizomes, which may be protected from heat damage by sequestering in moist duff layers [2,22,59].

Long-term effects of fire on woodfern populations may be similar to the effects of other types of disturbance, such as blowndown or logging (see Successional Status). Within woodfern forest habitats, fire and other types of disturbance may similarly affect stand structure.

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
Several studies have demonstrated that woodferns can regenerate vegetatively following fire. Depending on fire severity, woodfern populations may or may not be negatively impacted in the first few years following fire.

Chapman and Crow [22] examined the effects of prescribed fire on groundlayer vegetation in an eastern white pine stand in southeastern New Hampshire. Relatively cool, surface-running head fires were conducted in mid-October 1976 and mid-April 1977. Spinulose woodfern was present (no quantitative measure was reported) in both prefire and postfire measurement plots, although it was absent from adjacent unburned control plots. Spinulose woodfern regenerated vegetatively, sprouting rapidly following burning [22].

Multiple, biennial prescribed burns, as well as single burns, conducted in a red pine and eastern white pine plantation in southwestern lower Michigan, yielded no discernible impact on spinulose woodfern presence compared with unburned controls. Fires were low-severity understory burns (<3.3 feet (1 m) flame lengths) in which duff consumption was generally <0.59 inch (1.5 cm) and woody fuels >0.98 inch (2.5 cm) in diameter were unconsumed, although understory vegetation was nearly all top-killed. Treatments consisted of either a) 3 biennial May burns, beginning in 1991, b) a single May, 1991 burn, or c) an unburned control. Mean percentage cover and relative frequency for spinulose woodfern were compiled from sampling conducted every 4 weeks from May to September. Although treatment differences were not statistically tested at the species level, the data suggest that burn treatments had little short-term effect on spinulose woodfern cover or frequency [114]. For a detailed discussion, see the Research Project Summary of this study.

Spinulose woodfern abundance following burn treatments [114]
Treatment  Year Mean percentage cover Relative frequency
Biennial burning 1994 (2 burns) 3.24 3.4
1995 (3 burns) 2.04 3.6
Single burn 1994 4.39 4.2
1995 7.58 5.1
No burn 1994 2.88 5.1
1995 3.00 6.1

Hamilton and Peterson's [59] study of vegetation response to clearcutting followed by slash burning in a hybrid spruce (Picea glauca P. engelmannii) forest in interior central British Columbia suggests that spreading woodfern was initially reduced but not eliminated by fire, with spreading woodfern quickly recovering to near pretreatment levels. Cutting occurred over winter in 1987 and 1988, the site was burned in early September 1988, and vegetation data were collected in summer. The fire was considered "low- to moderate-severity" [59]. A more detailed discussion of this study is available in the Research Project Summary of this study.

Spreading woodfern and tree species abundance following clearcutting and slash burning (adapted from [59])
  Prefire (postcutting) Postfire year
1
Postfire year
2
Postfire year
3
Postfire year
5
Postfire year
10
Mean spreading woodfern cover (%) 1.67 0.25 0.93 1.42 0.78 0.33
Mean spreading woodfern frequency (%) 100 33 67 83 83 33
Total tree spp. cover (%) 1.04 0.44 0.89 1.61 3.65 22.12

Hamilton's Research Papers (Hamilton 2006a, Hamilton 2006b) provide further information on prescribed fire and postfire response of plant community species including spreading woodfern.

Regardless of how woodfern abundance is affected in the first few years following fire, short of its elimination, it is likely to decline within a decade or so following stand-replacing fire. In the above study, despite postfire recovery to near-prefire levels by year 3, spreading woodfern abundance showed a subsequent decline in postfire years 5 and 10. Although not part of the study's objectives, comparison of spreading woodfern abundance with total tree species cover data indicates that the decline in spreading woodfern abundance may have been due to interference from tree regeneration [58]. This response is generally predicted by Oliver's [116] 4-stage forest stand development model, in which all the growing space freed by a stand-replacing disturbance becomes occupied by the initial cohort of regenerating plants (stand initiation stage), followed by a stem exclusion stage during which growing space is limited and height stratification excludes many low-growing individuals.

Another study of vegetation response to clearcutting followed by slash burning in an Engelmann spruce-subalpine fir forest in south-central British Columbia [58] yielded results similar to Hamilton and Peterson's [59] (see Discussion and Qualification of Fire Effect for their treatments and results). Vegetation was sampled the summer before cutting, and 1, 2, 3, 5, and 11 years after burning [58].

Mean cover (%) of spreading woodfern prior to clearcutting and 1,2,3,5, and 11 years after burning [58]
Years after burning Cut and unburned  Cut and spring burn Cut and fall burn
Precut 0.62 0.65 1.47
1 2.75 0 1.60
2 1.77 0 1.53
3 0.69 0 0.41
5 0.62 0 0.47
11 0.41 0 0.33

Differences in cover between burned and unburned treatments were not statistically significant after year 1 (P>0.06), and comparison of cover data between the unburned and fall burned treatments suggests that the spreading woodfern population was unaffected by fall burning, separate from the influence of clearcutting [58]. As in Hamilton and Peterson's [59] study, a decade following clearcutting and slash burning, spreading woodfern abundance was on a downward trajectory [58]. Stand-replacing fire might similarly change the structure of the forest and, assuming spreading woodfern survived the initial disturbance, act similarly on spreading woodfern populations over 10 or so years.

Other studies also suggest that woodferns are not abundant on previously-burned sites, at least during the first few postfire decades. Spreading woodfern cover 15 to 20 years after prescribed burning in Lutz spruce forests of the Kenai Peninsula, south-central Alaska, ranged from 0% to 4%. On prefire and unburned plots, spreading woodfern cover ranged from 1% to 35%. Neither detailed information on immediate fire effects nor fire behavior parameters were provided [19].

In a 25-year-old burn in a mature, southern Appalachian red spruce-Fraser fir forest, mountain woodfern was not present in postfire plots. Although no prefire or unburned vegetation data were provided, it was noted as an important herb-layer species in both mature and second-growth logged red spruce-Fraser fir forests in the surrounding area. Tree-layer data suggest that the fire was mainly stand replacing [140,141].

Long-term studies, while sparse, indicate that response of woodfern populations to fire may be difficult to predict during late-successional stages. Simon and Schwab [145] examined vegetation across a chronosequence of black spruce-dominated stands in western Labrador. Fire-disturbed stands of ages 2, 18, and 40 years, as well as 80- and 140-year-old forest stands of unknown disturbance origin were sampled. Although the stand-originating disturbance was unknown for the older stands, it was noted that stand-replacing fire has been the dominant natural disturbance in the region. Average spinulose woodfern cover was 1.09% in the 2-year-old stands, and 0% for the remaining stands. In a hybrid spruce (Picea glauca P. engelmannii) forest in central interior British Columbia, spreading woodfern was found exclusively in late-seral stands (>140 years since fire) and not in midseral (50-80 years since fire) or early-seral stands (<14 years since fire) [37].

De Grandpre and others [30] sampled vegetation at 8 southwestern Quebec boreal forest sites. Each site represented a discrete postfire age, ranging from 26 years to 174 years since the last fire. These data suggest that spinulose woodfern presence is probably greatest in early postfire succession in these boreal forests, but that it may persist at lower levels for a substantial time without fire recurrence [30].

Frequency (%) and cover (%) of spinulose woodfern for a series of postfire age classes in a northwestern Quebec boreal forest [30]
  Years since fire
26 46 74 120 143 167 174
Frequency +- --- --- --- --- +- ---
Cover 3.5 % 0.1 % 0.1 % 0.9 % 0.1 % 0.2 % 0.1 %
+- : frequent (>50% occurrence) at the whole site (100 m quadrat scale) but infrequent at the 1 m quadrat scale
---: infrequent (<50% occurrence) at the whole site scale and infrequent at the 1 m quadrat scale

This fire study also provides information on postfire responses of plant species in communities that include woods strawberry:

FIRE MANAGEMENT CONSIDERATIONS:
As of this writing (2007) there was very little published specifically concerning management of woodferns and fire. Johnson [71] suggested that because spreading woodfern grows best in organic soil horizons, it is probably not enhanced by fire. Hamilton and Peterson [59] concluded that spreading woodfern "is fairly sensitive to burn severity and could be eliminated by burning".


MANAGEMENT CONSIDERATIONS

SPECIES: Dryopteris spp.
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
Spinulose woodfern is preferred moose forage in Isle Royale National Park [16,99]. Spreading woodfern is minor component of the blue grouse winter diet [150] and was eaten in small amounts by mountain goats on southeastern Alaska winter rangeland [49].

Palatability/nutritional value: In-vitro simulation suggests that spinulose woodfern is among the most highly digestible moose forage species on Isle Royale, northern Michigan [16].

Cover value: No information is available on this topic.

VALUE FOR REHABILITATION OF DISTURBED SITES:
No information is available on this topic.

OTHER USES:
Woodferns are traditional food for Native Americans along the Pacific coast, at least from British Columbia to western Alaska [63,82,134]. Young fronds are eaten in spring [63,137]. Rhizomes and stalk bases are collected in fall and steamed or roasted [57,134,137,164]. Roots are used as flammable material for a "slow match" [164] and also pounded into a pulp and applied to cuts. Leaves may be soaked for several days and the liquid used for a hair wash [57,137].

OTHER MANAGEMENT CONSIDERATIONS:
No information is available on this topic.

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