TAKEN FROM PUBLICATIONS SUBMITTED BY BRUCE G. MARCOT AND COLLEAGUES,
INTERIOR
COLUMBIA BASIN ECOSYSTEM MANAGEMENT PROJECT, USDA FOREST SERVICE AND
USDI
BUREAU OF LAND MANAGEMENT
Bruce G. Marcot
Wildlife Ecologist
15 August 1997
(Note: Not included in these extracts are tables, figures, and references; these can be found in the original documents.)
---------
from:
Marcot, B. G., M. Castellano, J. Christy, L. Croft, J. Lehmkuhl, R.
Naney, R. Rosentreter, R. Sandquist,
and E. Zieroth. In press. Terrestrial ecology assessment.
Pp. xxx-xxx in: T. M. Quigley and S. J.
Arbelbide, eds. An assessment of ecosystem components in the
interior Columbia Basin and portions of the
Klamath and Great Basins. USDA Forest Service General Technical
Report PNW-xxx. USDA Forest
Service Pacific Northwest Research Station, Portland, OR. xxx
pp.
Kinds of Fungi and Their Relation to Fire, Dung, and Host Plants
A number of fungi species are phoenicoid, fruiting after fire.
Effects of fire intensity on their sporocarp phenology
(seasonality) are poorly known.
Forest Lichens
The lichen flora of the forests of the assessment area is dominated
by arboreal black forage lichens, Bryoria spp.,
also commonly known as beard lichen or black tree lichen (TES 1995).
Some of these forests are adapted for fire,
although the natural fire frequency has been greatly altered by humans
through fire suppression management (TES
1995). Fire suppression often has resulted in dense forests of
different species composition than the open, park-like
conditions that were maintained by natural fires. Dense, closed
stands of trees contain fewer lichens than open
stands of trees. American Indians used black tree lichens extensively
for food, often mixing it with their
pemmican.
Uneven-aged management of stands (preserving seed trees) would conserve
the legacy of lichens and allow them to
recolonize regenerated trees. Black tree lichens are fairly good
dispersers into areas disturbed by fires. Natural
forest burns generally leave clumps of unburned trees with intact lichens
and even portions of lichens on burned
trees and snags. These legacy stocks, which are typically absent
from large clearcuts and dense forest stands, serve
to “seed” the regenerating forests. Site treatments such as piling
and slash burning also decrease the remnant
lichen legacy. Many managed forest stands in the assessment area
are surface-treated to yield dense regeneration,
rather than managed to encourage natural regeneration. These
treatments and other surface treatments, combined
with overstocking of artificial plantings, produce dense forests that
do not favor the growth of forage lichens. Such
forest management practices have probably decreased the abundance of
the forage lichens, but the application of
uneven-age forest management and retention of clumps of legacy trees
will help improve the potential for lichen
regeneration.
The Northwest Forest Plan (based on FEMAT 1993) addressed the topic
of lichen conservation for the forests west
of the Cascades, but there have been no such scientific studies on
this topic in the current assessment area. Basic
lichen floristic surveys and practical applied research into maintaining
lichens in managed forests of the
assessment area are sorely needed. Additional work will need
to be done to elucidate effective strategies for
maintaining and restoring lichens in harvested and burned portions
of these forests.
... Many of the microbiotic lichens found in the assessment area are
widespread globally, yet the area they now
cover in the United States has been greatly reduced compared to historic
times. The major threats to survival of
microbiotic crusts in the assessment area include: invasion of
exotic annual grasses and associated increases in
fire frequency; ... Increased fire frequency (more than 40 times
historical frequencies) owing to the introduction of
cheatgrass has led to dramatic changes in grassland ecosystem structure
(Whisenant 1990). Much of the shrub
steppe has been converted to a dense, closed stand of annual exotic
grasses to the exclusion of microbiotic crust
communities. ...
Bryophytes of Rocks
... Because of their position on slopes and ridges, stands at the base
of outcrops are subject to catastrophic fire, and
the bryophytes in this species group probably develop only after long
periods of canopy stability. ...
Bryophytes of Dry Soil
... In contrast to pioneer associations on disturbed soil, these
crusts take many years to form, are long-lived, and
suffer long-term damage from fire, livestock trampling, and off-road
vehicle traffic (Beymer and Klopatek 1992,
Johansen and others 1984). ...
Predatory Arthropods and Down Wood
In some cases, maintaining predatory function may be as simple as maintaining
structures within the landscape
that predators are known to require, such as Camponotus modoc use of
down wood. Down wood, snags, specific
habitat features (such as hydrological functions of bogs and springs),
forbs, shrubs, and trees of various species and
sizes are features to which predaceous arthropods are correlated, much
like vertebrates. But unlike the vertebrates,
virtually nothing is known about how particular human management practices
influence the species composition,
abundance, and distribution of predatory arthropods within a given
area and the effects of management on
ecological function and ecosystem processes. A landscape composed
of a balanced mosaic of habitat types will
likely have a balanced set of ecological functions.
... An example illustrating the intricacy of predation effects is the
central importance of down wood. Because
Camponotus modoc nests only in large diameter down wood, maintenance
of adequate large-diameter wood will
favor larger populations of this important spruce budworm predator.
Further, since Camponotus modoc is also the
primary prey of pileated woodpeckers (Dryocopus pileatus), and since
these woodpeckers excavate cavities used by
a variety of insectivorous birds, management of down wood can provide
substantial benefit by encouraging the
maintenance of larger populations of budworm predators, principally
ants and birds.
Thatch Ants and Fire
In the most basic sense, any disturbance that affects habitat will affect
the species that depend on that habitat. For
example, short fire return intervals in cheatgrass-dominated rangelands
in southern Idaho will very likely
eliminate dominant predator species such as the thatch ant Formica
obscuripes. Thatch ants have the following
ecological functions: thatch ant nests provide habitat for over
100 species of other arthropods, serve as
overwintering and foraging habitats for small mammals, and concentrate
nutrients on a local scale. In addition,
thatch ant workers care for several species of aphids and other Homoptera,
are predators and scavengers of other
insects, and the workers and pupae are prey for other vertebrate insectivores.
Where they occur, thatch ants are
probably responsible for the majority of secondary production through
conversion of honeydew and prey proteins
into ant protein. Although thatch ant colonies can survive fire
by maintaining the queen and brood below ground,
post-fire survival is challenged by a lack of resources since the sagebrush-feeding
Homoptera that the ants depend
on for honeydew energy are typically eliminated. Hence, thatch
ant colonies are generally reduced by fire to less
than 20 percent of their original size. Fire events every few
years will likely drive these challenged colonies to
extinction.
A general trend in the northern Great Basin is the removal of sagebrush
and other shrubs upon which Homoptera
feed and the subsequent loss of the thatch ant. Vegetation communities
and ecosystems with short fire-return
intervals (typically cheatgrass-dominated) will tend to favor "weedy"
ant species with different ecological
functions. In general, because many of our ecosystems have been
modified significantly by fire suppression,
grazing, and the introduction of exotic plant species, use of prescribed
burning may not meet the objective of
returning the land to its previous condition. Hence, it is suggested
that prescribed burning be used with caution
with native species in mind.
Management and Invertebrates
Habitat composition and structures— The alteration of the structure
of the forest canopy layer from tree harvest,
tree stand improvement activities, or wildfire affects several functional
groups of invertebrates. The altered forest
stand may be more or less hospitable to various herbivores resulting
in different amounts of nutrients in foliage
falling to the litter or different rates of subsequent tree mortality.
The changes may result in varying quality and
quantity of prey available to predators including both invertebrate
and vertebrate species. Changes in density or
composition of the tree canopy can affect habitat for predators that
help control population irruptions of pest
species. Also, canopy changes cause microclimatic changes in
the understory, and coarse woody material and litter
environments which may be detrimental for some species. For example,
if the light/moisture regime is changed
sufficiently, the understory angiosperm flora may change, resulting
in affects upon pollinators, herbivores, and
predators. These changes in forest stand structure may be inimical
to species such as land snails whose lack of
mobility may prevent them from seeking conditions in disjunct patches
of forest habitat. In addition, coarse
woody material may dry out more quickly, thereby affecting the internal
environment within standing and down
dead trees and altering suitability for decaying-wood dwelling invertebrates.
Soil structure and soil chemistry— Maintenance of forest soil
chemistry and structure helps to sustain soil health
and fertility. This is vital to retaining forest and range productivity
and biodiversity. Chemical changes of soil
from fire and structural changes of soil from compaction or mixing
of soil layers are two results of management
practices that are of concern. Fire, whether natural or human-caused,
has the potential to consume the litter and
coarse, woody material that are the primary sources of carbon and other
elements necessary for the soil food web.
Erosion, resulting from loss of soil-binding materials, further depletes
the capacity of the soil. Fire can volatilize
nutrients found in the upper horizon of the soil and change water-retention
characteristics. Structural changes of
soil from either compaction or soil mixing can have long-lasting effects
on successional patterns and duration.
These effects are expected with multiple management entries into a
forested area.
... Two areas of concern for invertebrates are the direct effects of
fire on populations and the role of fire in forest or
range succession and soil chemistry. In fire-adapted systems,
direct effects on invertebrate populations are thought
to be slight. However, in systems where large volumes of fuel
(litter and coarse woody material) are present,
higher intensity fires may pose hazards to slow-moving organisms such
as land snails. Direct effects on
invertebrates will be reduced if refugia of litter and coarse woody
material are retained.
Fire removal of organic matter has opposite effects on forest and range
succession. In the forest, loss of organic
matter may change the ratio of fungi:bacteria to favor bacteria.
This change in ratio favors grasses rather than
woody vegetation, not necessarily the direction desirable in forestry.
In grasslands, the consumption of organic
matter and the subsequent change to a bacteria-dominated food web is
beneficial to the maintenance of grasses.
The effects on invertebrates by early-season fires in cheatgrass with
its damage to native perennial grasses is
unknown.
Coarse woody material provides habitat for prey of other organisms,
serves as primary habitat for invertebrate
predators, and serves as a carbon source for the soil food web.
It is not known how much litter and coarse woody
material and what sizes are necessary to continue ecosystem functions
of associated invertebrates. It is assumed
that the standards to provide prey for vertebrate species will suffice
to continue the functions of invertebrate
populations.
... On rangeland and in open forests, fire occurring during active bee
nesting and foraging seasons results in direct
mortality of bees and decreases habitat for wood-nesters. Since
closed forests have no significant use by bees,
seasonality of fire is inconsequential; but seasonality of fire is
of consequence in rangeland and open forests.
... Fire has little direct effect on [grassland herbivorous] insect
populations unless burns are timed to kill all
individuals that would emerge that season. A greater effect is
how fire can shift plant community composition. If
burning, especially in association with other disturbances, results
in areas that are dominated by early successional
forbs, outbreaks of some herbivorous invertebrate species may
occur, at least in the short-term. A "cool" fire may
have positive effects on moths and butterflies by opening up the community
to their preferred food plants. A "hot"
fire could result in mortality of shallow-rooted plants which could
decrease diversity of closely associated
herbivores.
Amphibians and Down Wood
... Distribution and abundance of many amphibian species are more closely
associated with specific substrates
(such as down wood) and microhabitat conditions (such as deep, moist
talus), than with general vegetation cover
types and structural stages. ... A few species, such as the Larch
Mountain salamander (Plethodon larselli), may lay
eggs in moist habitats but are associated with down wood or talus as
adults rather than aquatic environments. ...
Birds and Fire
Little information is available on the effects to ground-nesting birds
of fire and fire suppression, season of burn,
and changes in vegetation pattern resulting from burns and fire suppression.
Although general trends have been
reported, in the assessment area species-specific effects on bird population
density and trends from livestock
grazing, changes in distribution and density of nest parasites (principally
brown cowbird), changes in insect
populations, and availability of free water are poorly known.
Resource management, including fire suppression
and timber management, and the resulting changes in the structure and
distribution of vegetation communities has
influenced the distribution and abundance of many avian species.
For example, the amount of old, single-strata,
interior ponderosa pine forests that have been maintained by frequent,
low-intensity fires have declined by
approximately 80 percent from historic conditions to present.
Species associated with this community, such as
white-headed woodpeckers (Picoides albolarvatus) and flammulated owls
(Otus flammeolus), have declined in
abundance and are considered sensitive by federal agencies. Spotted
owls (Strix occidentalis caurina) and marbled
murrelets (Brachyramphus marmoratus), associated with late-successional
conifer forests in the Cascade
Mountains, likely have also declined in abundance as a result of loss
of habitat (Thomas and others 1994),
although some mixed-conifer forest habitat for spotted owls may have
increased in recent decades on the east slope
of the Cascade Mountains as a result of fire suppression. Some
non-forest communities and associated vegetation
structures have also greatly changed as a result of human activities.
Reptiles and Fire
Fire suppression has induced conifer encroachment on certain shrub habitats
and has contributed to loss of habitat
for reptiles. Additionally, fire suppression and intensive grazing
has altered the vegetation structure of some of the
shrub habitats. If intensive occurs in these habitats under current
conditions, the shrubs over large areas may be
lost and the area converted to grassland; this would reduce habitats
for some species closely associated with shrub
habitats, including the Mojave black-collared lizard.
Management of Birds, Mammals, and Fire
... Fire suppression and intensive forest management has altered much
of the forested areas in the assessment area.
Associated with this harvest is increased access into areas of previously
low human use. These largely inaccessible
areas were refuges to some species that are sensitive to human disturbance
like the wolverine and grizzly bear. ...
Management of Wildlife and Down Wood
... Threats to species that require late forests succession and
associated structural components such as large snags
and down, woody debris include the reduction or loss of these components,
changes in wood decay rates, and
declines in insect (primarily ant) populations (Bull and others 1995).
...
... Declines in riparian, wetland, old forest macrohabitats, and woody
debris microhabitat accounted for the bird
species tallied as incurring decreasing habitat. ...
... Losses in mammal habitat appeared to be associated with conversion
of rangelands to agriculture and loss of
some old-forest macrohabitat and woody debris microhabitat. ...
... The carib beetle Pterostichus protractus (Carabidae) associates
with fallen woody debris and litter, as well as
with bases of herbaceous plants, rocks, and snags. Among vertebrates,
at least 4 shrews, shrew-mole, and 3
songbirds show close associations with litter and duff. ...
Species Associated with Down Wood
Among the listed, candidate, or potential candidate species of plants,
46 fungi species, the decayed wood bryophyte
group, and 5 lichen groups were identified in the database as associated
with down wood. At least 11 invertebrate
species were identified as examples of the several thousand species
associated with down wood. Two examples are
the checkered beetle, Enoclerus sphegeus (Cleridae), which uses both
fresh down wood and also intact but older
down wood; and the leafcutting bee Osmia bruneri (Megachilidae), which
uses snags and stumps, but also uses
down wood stems with abandoned beetle burrows. Additionally,
82 species of amphibians, reptiles, birds, and
mammals show correlations with down wood.
Interestingly, our investigations uncovered a small set of species that
seem, in part, to specialize on bark piles at
the base of snags. These include at least the invertebrate Pseudogarypus
hesperus (Psendogarypidae: Chernilldal),
and two amphibians, the northwestern salamander Ambystoma gracile (which
also uses down logs), and the Larch
Mountain salamander Plethodon larselli (which uses bark piles especially
in the driest season in sites also with
moist talus and low soil content).
Species Associated with Litter And Duff
Some example species listed in the SER database that are closely associated
with litter and duff conditions include
6 species of fungi, the humus/duff bryophyte group, one lichen species
and two lichen groups (nitrogen-fixing soil
lichens, and rotten log and tree base lichens). The carib beetle
Pterostichus protractus (Carabidae) associates with
fallen woody debris and litter, as well as with bases of herbaceous
plants, rocks, and snags. Among vertebrates, at
least 4 shrews, shrew-mole, and 3 songbirds show close associations
with litter and duff.
Vertebrate Species Associated with Fire Processes And Insect Outbreaks
Plant species show various responses to fire suppression, frequency,
intensity, and seasonality (table 15). Response
to fire by fungus, lichen, and bryophyte species generally is not known,
and response by vertebrate species is not
easily depicted.
Among the many invertebrates that respond in various ways to fire, three
examples are the lace bug Acalypta
cooleyi (Tingidae), which is adversely affected by prescribed (and
unprescribed) range fires that burn mosses; bark
beetles including Dendroctonus pseudotsugae (Scolytidae), which are
positively correlated with forest fire intensity
and that associate with forest stands with severe drought (but not
with forest stands with few to no fire-injured
Douglas-fir trees greater than 30 cm dbh within a 10-km radius); and
the thatch ant Formica obscuripes
(Formicidae), which is positively correlated with fire frequency.
Among the vertebrates, western tanager (Piranga ludoviciana) and purple
martin (Progne subis) respond positively
to recent burns (tanagers more in cottonwood riparian forest, and martins
in locations near water). Red-headed
woodpecker Melanerpes erythrocephalus (rare in the assessment area)
and orange-crowned warbler (Vermivora
celata) respond more to older burns, the woodpecker in cottonwood/oak
forests and open woodlands, and the
warbler more in brushland, riparian, and fire-generated shrubby montane
sites with deciduous trees in the
understory. Lewis' (Melanerpes lewis), black-backed (Picoides
arcticus), and three-toed (Picoides tridactylus)
woodpeckers, along with mountain and western bluebirds (Sialia currucoides
and Sialia mexicana), associate with
sites where fires have killed the forest overstory.
Black-backed and three-toed woodpeckers associate with mid- to high-elevation
forests following irruptions of
insect populations such as bark beetles. In the eastern portion
of the assessment area, the uncommon Tennessee
warbler (Vermivora peregrina) increases after outbreaks of spruce budworm.
Rodents and Fire
... Rodents, especially red-backed voles, play key roles in re-establishing
trees by burying seeds and spreading
spores of beneficial symbiotic fungi, especially after timber harvest
or fires. However, some evidence suggests that
if the clearing is too large, they will aid in re-establishment of
trees only along the edge of forest cover (A.
Thomas, personal comunication; Mills 1995).
Plants, Bacteria, and Fire
... Species that stabilize soils on post-fire sites include several
species of milk-vetch (Astragalus spp., Chaenactis
cusickii, Penstemon peckii, and others; also see table 15). Many
other plants not listed in the SER database likely
perform this function more widely throughout the assessment area.
The beneficial bacteria Microcoleus also serve
to stabilize soil and prevent erosion.
Fire and Desired Future "Dynamics"
Given the ever-changing nature of ecological communities in the assessment
area, particularly regarding potential
effects of fire, perhaps the very concept of defining "desired future
conditions" for planning could be replaced with
a concept of describing "desired future dynamics". That is, long-term
evolutionary potentials can be met only by
accounting for potential future changes in conditions. No one
condition can be static for long; witness the recent
eruptive, intense fires in parts of the assessment area, resulting
in part from a long history of fire suppression and
vegetation changes. Impending changes in regional climates, too,
have the capacity of causing great shifts in
composition of ecological communities. For example, providing
for elevational "corridors" to allow upslope shifts
of vegetation over the next several decades may be vital to helping
conserve the long-term evolutionary potential
of individual species.
Information Research Needs and Fire
Additional study is needed on how manipulation of natural processes,
such as fire and ecological succession, can
influence genetics and viability of populations clearly dependent on
those processes (F. Samson, pers. comm.).
Studies are also needed to determine lichen recovery after fires, and
their dispersal patterns by species, by groups of
species, and by forest types.
The implications of prescribed burning on plant and subsequent invertebrate
diversity are unknown. Factors such
as fire interval, intensity, duration, season, patchiness, and spatial
extent need to be examined to determine their
effects on plant community composition and diversity and abundance
of invertebrate herbivore and predators.
Studies are needed on effects on ground-nesting birds and their habitats
of fire occurrence, fire suppression, season
of burn, and changes of vegetation pattern resulting from burns and
fire suppression.
Appendix B. List of contract and internal reports provided for this assessment. [dealing with fire]
Bunting, S.C.; Peters, E.F. 1994. Impact of fire management
on rangelands of the intermountain west. Moscow
ID: Dept. of Range Resources, University of Idaho. 24 p. + tables.
Table 15— Plant species associated with various aspects of fire dynamics
(excluding fungi). BS = bryophyte
group, L = lichen, LG = lichen group, P = vascular plant, PG = vascular
plant group (source: SER database) [table
not included here; please see publication]
============================== from:
Marcot, B. G., L. K. Croft, J. F. Lehmkuhl, R. H. Naney, C. G. Niwa,
W. R. Owen, and R. E. Sandquist.
Submitted. Macroecology, paleoecology, and ecological integrity
of terrestrial species and communities of
the interior Columbia River Basin and portions of the Klamath and Great
Basins. General Technical
Report PNW-GTR-XXX. USDA Forest Service. XXX
pp.
Changes of Vegetation and Fire
... Changes in rangeland communities have been due to increased fire
frequency associated with the invasion of
exotic grasses, primarily cheatgrass (Bromus tectorum).
Since historic times, there has been a slight increase in overall forest
cover (fig. 8) because fire suppression has
encouraged expansion of juniper woodland and interior Douglas-fir forest
into native sagebrush and grassland
communities.
Changes in Biota and Fire
Local climate changes in lowland environments also may result in changes
in fire regimes. Plants that respond
differently to occurrence, intensity, frequency, and seasonality of
fires likely would show differential increases or
decreases under changing fire regimes. Marcot and others (in
prep.) present a list of rare or potentially rare plants
of the basin assessment area showing their orientation to fire regimes;
this list can be consulted to hypothesize how
species might respond. Results are quite mixed. For example,
overstory lethal fires may benefit 7 lichen groups, 9
plant groups, and 9 vascular plant species, but harm a different set
of 5 bryophyte groups, 11 lichen groups, 2 plant
groups, and 11 vascular plant species. Increasing fire frequency,
increasing fire-suppression activities, and
changes in the seasonality of prescribed and natural fires--all of
which may occur from regional changes in
climate--also have mixed results.
Invertebrate responses to changes in fire regimes is poorly studied
and largely unknown, except for forest insect
pests (Hann and others, in prep.). Among vertebrates, stand-replacing
fires can certainly change community
composition. Hutto (1995) documented differential response by
bird species to stand-replacement fires in the
northern Rocky Mountains, and noted that one species--black-backed
woodpecker (Picoides arcticus)--was nearly
restricted to sites with standing fire-killed trees. Hutto also
listed other bird species that may benefit over the long
term from stand-replacement fires.
Old Open Ponderosa Pine Forests and Fire
... We expect, with careful salvage thinning and logging of many lower
elevation forests, along with prudent
reintroduction of fire into these ecosystems, that late seral ponderosa
pine single-layer forests eventually can be
encouraged to return. ...
Recreating Historic Conditions and Fire
... Kay (1994) concludes that, historically, Native Americans commonly
determined the structure of entire plant
and animal communities by hunting and by setting fires (also see papers
cited in Knowles and Knowles 1993), and
that a current "natural regulation" approach to management does not
recognize and thus probably would not
replicate such historic conditions. ...