Botrychium simplex E. Hitchcock (little grapefern) - Colorado Natural ...

1997), B. pedunculosum (Wagner and Wagner 1986),
B. mormo (Wagner and Wagner 1981, Chadde and
Kudray 2001a), B. multifidum (Wagner and Devine
1989), and B. campestre and B. gallicomontanum
(Farrar and Johnson-Groh 1986). Ollgaard (1971)
reports the presence of B. lanceolatum, B. lunaria, and
B. multifidum with B. simplex in Greenland.
Within Region 2, Botrychium simplex is also
frequently documented in genus communities.
Colorado element occurrence records note the presence
of B. echo, B. hesperium, B. lanceolatum, B. lunaria,
and B. minganense with B. simplex (Colorado Natural
Heritage Program 2006). Botrychium simplex has
been found with B. campestre in Brown County,
Nebraska (Farrar and Johnson-Groh 1986, Farrar
personal communication 2003). Both B. campestre
and B. ‘michiganense’ have been documented from the
Bearlodge Campground in Crook County, Wyoming,
but they have not been found in close association with
B. simplex at this location. Botrychium simplex has
been found with B. pallidum at three locations on the
Black Hills National Forest, and with other unidentified
taxa at one location (Burkhart personal communication
2006). Outside Region 2, B. simplex has been found
with B. multifidum at two sites in Yellowstone National
Park (Whipple personal communication 2003), and
these species are often found together (Crook personal
communication 2003, Farrar 2005).
The coexistence of species of Botrychium in genus
communities is interesting from a community ecology
standpoint. If the members of genus communities
occupy the same niche, then they coexist in violation
of Gause’s competitive exclusion principle (Krebs
1972). Because water, nutrient, and some carbohydrate
uptake are mediated by mycorrhizae, it is possible that
even if genus community members depend on the
same resources, coexisting plants are not engaged in
direct interspecific competition. Competition may be
for access to the mycorrhizae if it is occurring at all.
No research has been done on Botrychium species with
respect to these issues. Wagner and Wagner (1983) offer
an interesting discussion of this issue from a population
biology standpoint.
Moonworts clearly tolerate some degree of
grazing, but there is little information on which to base
management decisions regarding livestock and wildlife
grazing (Johnson-Groh and Farrar 2003). Montgomery
(1990) found that even repeated removal of the leaf
of Botrychium dissectum (subgenus Sceptridium)
for three years did not kill the plants, and on this he
commented (p. 178) “It is certainly remarkable that
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these plants persist.” Observations of B. minganense
and B. montanum by George Wooten on the Okanogan
National Forest in Oregon may offer some insights
into possible impacts of grazing on B. simplex. These
two species were monitored in a trampled spring area,
and while they appeared to benefit from disturbance
in lightly trampled areas, they were destroyed in
heavily trampled areas. Moderately trampled areas
were not affected (Roche 2004). The sensitivity of B.
simplex to grazing is not known, but some observations
suggest that it tolerates a moderate level of grazing. It
is documented from pastures in numerous locations
outside of Region 2.
There is some speculation that spores of at least
some Botrychium species are dispersed by mammals,
based primarily on observations of herbivory on the
sporophores of B. mormo (Casson et al. 1998, Wagner
personal communication 2002). Although dispersal by
animals has not been demonstrated for B. simplex, it is
possible that elk, deer, and other grazing ungulates act
as dispersal agents by eating the ripe sporophores in the
fall. This would be advantageous to B. simplex, since
elk and deer use B. simplex habitats and would tend
to deposit the spores in sites suitable for germination.
Small mammals may also function as short-distance
spore dispersal agents. The large, thick walled spores
of Botrychium species may be an adaptation to dispersal
by herbivores (Wagner 1998).
Plants on Vail Pass in the White River National
Forest have been subjected to small mammal predation
(Colorado Natural Heritage Program 2006). The plant
found at Copper Mountain also appeared to have been
partially eaten or damaged, but it also had been driven
over by a vehicle (Root personal communication 2003).
There are no reports of parasitism or disease in the
literature for any Botrychium species in Region 2.
CONSERVATION
Threats
Observations suggest that there are several threats
to the persistence of Botrychium simplex. In Ohio,
soil compaction, drying of habitat, and removal of
vegetation are threats to B. simplex (Ohio Department
of Natural Resources 2003). Chadde and Kudray
(2001b) noted that major threats to B. simplex in
Wisconsin, Michigan, and Minnesota include exotic
earthworms, exotic plants, succession to closed
canopy forest, major disturbance (ranked medium for
degree of impact), and canopy thinning and minor
disturbance (ranked low for degree of impact). Lorain