Shortleaf Pine/Bluestem Renewal
Shortleaf Pine/Bluestem
Grass Ecosystem Renewal in the Ouachita Mountains
George A. Bukenhofer
USDA Forest Service
Heavener, Oklahoma
L. D. Hedrick
USDA Forest Service
Hot Springs, Arkansas
Presettlement and Current Ecological Conditions
The 8 million-acre (3,237,600 ha) Ouachita mountain physiographic
region is located in west central Arkansas and southeastern Oklahoma.
The mountains are east to west trending and range in elevation from
500 to 2,700 feet (150-820 in). Travelers in this region prior to
European settlement described the landscape as dominated by pine
(Pinus echinata), pine-hardwood and mixed-oak (Quercus
spp.) forest communities with fire-dependent and floristically
rich grass and forb understories (Du Pratz 1774, Nuttal 1821, Featherstonhaugh
1844). Large grazing herbivores including elk (Cervus elaphus),
bison (Bison bison) and white-tailed deer (Odocoileus
virginianus) found suitable habitat there (Smith and Neal 1991).
Fire return intervals averaged less than 10 years for most sites
(Masters et al. 1995). Tree densities averaged 170 trees per acre
(420/ha), and the mean diameter was 11.4 inches (29 cm) (Kreiter
1995).
Today the Ouachita mountain landscape is still dominated by forests,
but the structure and composition of these forests have changed
dramatically. The density of trees has increased to 200 to 250 trees
per acre (494-618/ha) and the mean diameter is now 9 inches (23
cm) (Kreiter 1995). Understories are now dominated by woody vegetation
and certain once-dominant grasses and forbs are uncommon (Fenwood
et al. 1984, Masters 1991, Sparks 1996). Elk and bison have been
extirpated. Other species, such as Bachman's sparrow (Aimophila
aestivalis) and the brown-headed nuthatch (Sitta pusilla),
have been affected negatively by habitat loss (Jackson 1988) and
the red-cockaded woodpecker (RCW) (Picoides borealis) is endangered
(Neal and Montague 1991). Average fire return intervals now range
from 40 to more than 1,200 years (Masters et al. 1995).
Historical and present-day ecological communities of the 1.7 million-acre
(690,000 ha) Ouachita National Forest (ONF) are illustrative of
the above descriptions. Present day forests developed largely in
response to two factors: commercial exploitation of the original
forests and suppression of fires. Large-scale harvest of trees commenced
in the 1910s and by 1940 most of the virgin forests had been cut
(Smith 1986). With USDA Forest Service (FS) stewardship, the period
of forest regeneration that followed was marked by a strict policy
of wildfire suppression. That policy has largely remained in effect
to the present. The recent use of prescribed fire by managers, averaging
25,000 acres (10,100 ha) annually over the last decade (R. Miller
personal communication: 1995), has been insufficient to maintain
a woodland (i.e., tree/grass) ecosystem. The result is that such
ecosystems have all but disappeared from the Ouachita mountain landscape
(Foti and Glenn 1991).
Desired Ecological Condition in the Context of a Contemporary
Landscape
National forest lands are now subject to the philosophy of ecosystem
management. Ecosystem management has been variously defined, but
most definitions have two attributes in common: an overriding goal
to protect ecosystem integrity, sometimes called ecosystem health,
and an allowance for human uses that do not compromise ecosystem
integrity. The following are key elements of a large-scale ecosystem
management project on the ONF to restore the shortleaf pine-bluestem
grass ecosystem on 155,010 acres (62,730 ha), and in the process
provide sufficient habitat for a recovered population of the endangered
RCW and a sustainable supply of wood products (FS 1996).
Elements of Ecosystem Management
Increasing the use of prescribed fire and using tree cutting
to simulate natural disturbance patterns. Reduction of
basal area is accomplished by commercial thinning. Stand regeneration
is accomplished by commercial timber sales using irregular seed
tree and irregular shelterwood methods. With either regeneration
method, some of the seed trees are retained indefinitely. The size
of prescribed burning units encompasses landscapes rather than smaller
stand-sized blocks. The average size of prescribed burning units
has increased from 200 to 600 acres (81-243 ha), with some units
as large as 8,000 acres (3,230 ha) (R. Miller personal communication:
1997). In the past, most prescribed burning occurred during the
dormant season from October to March. We now include some burning
during the growing season to emulate fire patterns described in
Foti and Glenn (1991) and Masters et al. (1995).
Using a modified control strategy for wildfires.
Traditional FS policy has been to suppress all wildfires and minimize
the area burned regardless of whether the fire was beneficial to
resources. We found that a modified control strategy for wildfires,
which recognizes that some wildfires are beneficial and should be
allowed to burn, helps increase the area affected by fire each year.
In those instances where wildfires are burning within prescription,
occurring in areas determined to be desirable and not threatening
human safety or property, willdfires can be allowed to burn to the
nearest man-made or natural barrier. This change is an example of
"FIRE 2 1," a new effort initiated by FS leadership to
embrace the changing responsibilities in wildland fire management
in the 21st century (Apicello 1996). Goals for FIRE 21 include contributing
to restoring, maintaining and sustaining ecosystem function for
healthier forests and rangelands, and integrating wildland fire
management concerns and the role of fire into all agency management
programs, where appropriate.
Increasing rotation age. The minimum time between
regeneration cutting, or rotation age, has been increased from 70
to 120 years for shortleaf pine forest types. This allows for a
greater number of acres of older trees and results in increased
mast production from hardwoods retained in these pine stands. The
older trees are also required for RCW and other cavity-dependent
species. Cavity development is associated with a fungal heart rot
(Phellinus pinii) infection that usually does not occur
in stands less than 70 years of age.
Maintaining mixtures of native pines and hardwoods.
An important part of the restoration process is to replace non-native
trees when possible and retain mixtures of pines and hardwoods on
the landscape both among and within stands. Retention of mast-producing
trees has been a significant issue for the ONF
Developing and maintaining forested linkages among mature
forest habitats. Minimizing ecotonal differences between
contiguous stands and reducing habitat fragmentation is important
to many bird species. Each timber harvest proposal is examined for
ways to keep forest regeneration localized, which maximizes the
size of areas that support mature stands. We have increased the
size of regeneration areas from 40 to 80 acres (16-32 ha). Because
the total amount of regeneration per year or decade is fixed by
the rotation age, achieving it on fewer, larger areas rather than
many smaller areas reduces the total edge between dissimilar conditions.
This also maximizes the area of contiguous mature habitat.
Recognizing that people are an important part of this ecosystem.
Traditional uses of forest, such as timber harvesting, hunting,
firewood gathering, bird watching and fishing, continue while we
work to restore ecological (historical) conditions. No special limitations
are placed on the public while using the area. Project planning
incorporates local values through an extensive public involvement
program. Information from monitoring the effects of restoration
has been gathered through close collaboration with university researchers.
Detailed information is used to monitor the effectiveness of our
projects and guide the restoration effort.
Assessing Ecological Health
There are three areas by which the ONF can measure success at attaining
ecosystem health. Biodiversity, recreation opportunities and timber
supplies are used as "yardsticks" because all were significant
issues in recent planning efforts.
Biodiversity
Wilson et al. (1995) examined the breeding bird response to this
restoration effort. They found that 10 species of ground/shrub-foraging
species (yellow-breasted chat [Icteria virens], brown-headed
cowbird [Molothrus ater], Carolina wren [Thryothorus
ludovicianus), northern cardinal [Cardinal cardinalis],
wild turkey [Meleagris gallipavo], indigo bunting [Passerina
cyanea], northern bobwhite [Colinus virginianus],
chipping sparrow [Spizella passerina]) and shrub nesting
species (American goldfinch [Caruelis tristis], prairie
warbler [Dendroica discolor]) were favored by thinning
and prescribed burning, as compared with controls. Two ground-nesting
species, the ovenbird (Seiuris aurocapillus) and black-and-white
warbler (Mniotilta varia), declined in the same restoration
areas. Small mammals were found to have increased in numbers and
species on the same restored sites (Lochmiller et al. 1993). Sparks
(1996) found that prescribed burning produced higher herbaceous
species richness and diversity, and forb and legume abundance in
the project area.
Recreation Opportunities
Outdoor recreationists, including hunters and bird watching enthusiasts,
are attracted to these restored lands. In A Birder's Guide to Arkansas,
White (1995) featured the project area as a unique opportunity to
view RCW, brown-headed nuthatch and Bachman's sparrow. Discussing
the decline of the northern bobwhite, Brennan (1991) provided some
evidence that the forest-management techniques used here (reduction
of tree basal area, reduction of midstory and prescribed burning
every one to three years) resulted in higher bobwhite numbers. Masters
et al. (1996) examined whitetailed deer forage production on the
project area. They found that restoration efforts increased preferred
deer forage sixfold.
Timber Supply
Timber harvesting is an essential part of these restoration efforts.
The environmental impact statement for the FS long-term strategy
for RCW recovery (USDA 1995) in the Southern Region concluded that
this region-wide restoration effort would result in a gradual long-term
increase of timber supplies after an initial decline. The ONF implementation
of this strategy, because of favorable age class distribution, projected
that timber harvest volumes would remain constant in the next two
decades, and decline slightly from 29.2 to 27.5 million cubic feet
of wood by the fifth decade (Bukenhofer et al. 1994). The decline
in long-term sustained yield is largely a function of increasing
the rotation age from 70 to 120 years.
Other Considerations
Another measure of ecosystem health is the potential for reintroduction
of extirpated species. The elk has been successfully reintroduced
to three nearby locales, the Buffalo National River in northern
Arkansas, and the Pushmataha and Cookson Hills wildlife management
areas in eastern Oklahoma. Earlier attempts at reintroduction failed
due to brain worm (Parelaphostrongylus tenuis) infestation
(Carpenter 1973). Recent studies (Raskevitz 199 1) determined that
the intermediate hosts for the brain worm were snails (Gastropidae)
that were dependent on moist forest conditions where tree densities
were high, including a well-developed mid-story. They found that
elk preferred habitat that included open, drier forest conditions
unfavorable to the snails, and this preference yielded elk with
no clinical signs of brain worm infestation. In the future, we expect
that the drier forest conditions provided by shortleaf pine/bluestem
grass ecosystem renewal will supply a sufficient quantity of suitable
habitat capable of supporting a reintroduction of elk in the ONF.
Summary
The most influential laws relating to and governing FS land management
activities include the Multiple Use-Sustained Yield Act, Endangered
Species Act, National Forest Management Act, Clean Water Act and,
to a lesser extent, the Clean Air Act. For many, these laws present
conflicting direction and create an insurmountable operational,
regulatory and judicial tangle.
All of these laws predate direction issued by FS Chief Dale Robertson
to Regional Foresters in June 1992 in which he admonished them to
follow a philosophy of ecosystem management in their stewardship
of national forest lands. All of these legal mandates remain in
full force. Collectively, these laws can be summarized as requiring
that national forests be managed to allow for sustainable human
uses, both economic and non-economic, without compromising land
health. The role of the ecosystem management policy adopted by the
FS is to provide a single, all-inclusive philosophical context for
management that integrates the spirit and letter of these laws.
It puts sustaining land health first. We think this is appropriate,
for over the long term, it will be impossible to sustain human uses
without first sustaining the health of the land.
Our project is one example of ecosystem management. It embodies
elements of landscape ecology, restoration ecology and endangered
species recovery. It seeks to restore an entire ecosystem on portions
of today's Ouachita mountain landscape. This is not so much because
the landscape was prominent in pre-European settlement times, but
rather because it had almost disappeared along with its unique flora
and fauna. The project is mindful of Aldo Leopold's (1949) famous
dictum that saving all parts and pieces of the ecosystem is the
first precaution of intelligent tinkering. At least in this case,
we have demonstrated that managing for ecosystem integrity (health)
need not result in significant reductions in timber resources for
traditional human uses. This, coupled with the increased recreation
opportunities enumerated above, is a "win win" situation.
Acknowledgments
We wish to thank W. G. Montague and J. C. Neal for their useful
comments on an earlier draft of this manuscript.
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