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IPM - How it Works in the Smokies
Kristine D. Johnson - Supervisory Natural Resource Specialist, National Park Service, Great Smoky Mountains National Park, 107 Park Headquarters Road, Gatlinburg, TN 37738.
From: Exotic Pests of Eastern Forests, Conference Proceedings - April 8-10, 1997, Nashville, TN, Edited by:Kerry O. Britton, USDA Forest Service & TN Exotic Pest Plant Council
Many of the basic components of integrated pest management have been
known for centuries. Farmers have burned fields in the early spring to reduce
insects and disease organisms in their overwintering state; gardeners have
removed weeds mechanically by plow and hoe; timing of planting and harvest
can be planned to escape the most damaging life stages of certain pests.
IPM is simply the integration of a variety of control techniques with knowledge
of both the host and pest ecology, and the importance of monitoring and
long-term consequences. The objective is to minimize both pest damage and
adverse ecological impact. The National Park Service adopted integrated
pest management as an agency policy in 1980, and in the following three
years, reduced pesticide use by 70%. At Great Smoky Mountains National Park,
IPM strategies are used for control of exotic plants as well as for structures
and forest insect and disease problems.
IPM is both a decision-making process and a strategy; a standard definition
is "the selection, integration, and implementation of pest control,
based on predicted economic, ecological, and sociological consequences."
IPM seeks maximum use of naturally occurring pest controls, including weather,
disease agents, predators, and parasites. In addition, IPM utilizes various
biological, physical, chemical control, and habitat modification techniques.
Monitoring is an important aspect of IPM: it determines the need for and
timing of treatments, and is a measure of success/failure for a given technique.
Before development of synthetic pesticides, people relied on simpler
methods of pest control, such as cultivation, hand- picking, controlled
burns, and herbal remedies. In general, there were fewer exotic pests; in
the US today, we have over 4,500 species of foreign origin pests that have
established free-living populations. Many of these are beneficial, but others
have a significant adverse effect on health, agriculture, natural areas,
and industry. After World War II, synthetic pesticides such as DDT and 2,4-D
became widely available, and were used with little regard for long-term
consequences. Typically, these pesticides were broad-spectrum and affected
many non-target species, including such beneficial organisms as pollinators
and natural predators and parasites. Calendar spraying was standard, particularly
in agriculture. Pesticides were applied on a set schedule regardless of
observed need. Evaluation was minimal and treatments were applied at the
first sign of injury or even as a preventive measure.
As we now know, there were many problems with the post-war enthusiasm
for synthetic pesticides. Pests-plant, invertebrate, and microbial-could
become resistant within a surprisingly short time. Resurgence of pest populations
could occur when natural enemies ("beneficials") were killed,
resulting in pest populations even higher than before treatment. Secondary
pests could prove worse than the original target, e.g., mites following
after loopers were killed. Residual chemical had long lasting effects-DDT
is a famous example of increasing effects ascending the food chain and persisting
for years. Cancer and hormonal disruption were a common result of many synthetic
pesticides, and health hazards to humans are still surfacing. In addition,
spiraling costs caused even those unconcerned about environmental effects
to have second thoughts. Nature bats last.
IPM has many advantages. With minimal disruption of natural controls,
both cost and effort may be reduced. Damage to non-targets is reduced, as
well as undesirable environmental effects. IPM is most likely to produce
a permanent solution, and is cost-effective in both the long- and short-term.
The National Park Service mandate is to preserve resources unimpaired
for future generations; the primary threats to resources in all parks are
exotic species and air quality. The National Park Service has had a policy
since 1930 of controlling exotic species, including plants, animals such
as European wild boar, and some exotic forest pests, such as gypsy moth
and Dutch elm disease. Exotic plants are a problem in parks because they:
- displace native species and alter habitats. An example is Japanese
grass, a shade- tolerant exotic that can invade the entire herbaceous layer.
This has a particular competitive advantage in areas with high deer populations,
since deer dislike it;
- many exotics are much more labor-intensive to maintain. For example,
lespedeza planted along roadsides must be mowed much more often than lower-growing
species;
- some exotics are capable of hybridizing with natives, which alters
the genetic resource. Oriental bittersweet is one example;
- cultural landscapes are important resources in many parks and may be
obscured by exotics. Multiflora rose, for example, can spread from one
plant to cover an entire homesite in only a few years, as can privet, daylily,
and other common ornamentals;
- disturbed areas, such as forests impacted by fire, gypsy moth, or southern
pine beetle, are quickly invaded by such exotic trees as ailanthus or princess
tree if a seed source is within 4-5 miles;
- marginal habitats, such as riparian areas or cliffsides, are often
habitat for rare plants that are easily out-competed by exotics like mullein
or mimosa.
The National Park Service also manages many structures, developed areas,
and historic/cultural resources, as well as natural areas. IPM has many
applications throughout the agency. All pesticide use is approved either
at the regional or Washington level, and least toxic alternatives are required.
The Greak Smoky Mountains National Park is one of the largest areas in
the eastern US managed as wilderness-over 800 square miles in size-and also
the most heavily visited park in the NPS, with 9 million visitors each year.
Over 1,600 species of vascular plants have been recorded for the Park, and
of these, about 350 are not native. Only about 35 present a significant
problem. The Park has been working to eradicate a few of these - mostly
kudzu - since the 1950s, but our current program has been in place since
the late 1980s. In 1989, a park-wide survey was conducted, focusing primarily
on disturbed areas such as roadsides and old homesites, which provided a
good base for future eradication efforts. Information was gathered on each
species from literature review, database searches, and exchanges with other
land managers. The first principle of IPM is to know the biology of the
target species: how does it reproduce and dispurse? What is its typical
habitat? Is it evergreen, annual, or biennial? What are its natural ecemies
and weakest life stage? What are the most effective, least toxic means of
control? The Park, in cooperation with TNEPPC, recently compiled much of
the most useful information in a manual for management of exotic plants
for Tennessee, which is now available. After information is gathered, a
thorough survey and prioritization process follows. Important factors in
prioritization include:
- what is the level of impact and what resources are threatened, e.g.,
rare plant sites;
- how invasive is the species, e.g., those spread easily by windborne
seeds or carried by birds or water, and shade tolerance;
- threat to natural processes, and
- feasibility of control.
Monitoring and accurate record-keeping are crucial. At GRSM, a database
(dBASE) program was developed to analyze site and treatment data. The program
compiles information into reports which assist with seasonal planning. For
example, a priority report identifies the highest priority species for a
given season and location. Other reports, such as hours worked, amount of
herbicide used, and total treatment areas, are used to compile data for
annual summaries.
Treatment methods frequently used include hand-pulling (large volunteer
groups are helpful for such species as garlic mustard, mullien, barberry,
and mush thistle), selective herbicides, timing of application (evergreen
exotics, such as Japanese honeysuckle, English ivy, and privet can be treated
during the winter when many non-target natives are dormant, cut/stump treatment,
and basal bark herbicide applications. Post-treatment evaluations and experimental
trials are incorporated.
Prevention is the first line of defense against exotics. Regular inspections
of disturbed areas, particularly on the boundary are conducted, and Park
neighbors who share exotic sites have been contacted. Soil brought into
the Park for construction projects is inspected for such obvious problems
as Johnson grass rhizomes or mush thistle growing in the source area. Education
is a large component; the Park works closely with TNEPPC and other agencies
to help inform the public of the threats posed by exotics and to encourage
native alternatives for landscaping. Use of volunteers, particularly school
groups, helps to educate as well as accomplish work.
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