The Southern Pine Beetle
Chapter 11: Developing Integrated Management Strategies
Jack E. Coster — Applications Coordinator, Expanded Southern Pine Beetle Research and Applications Program, USDA Forest Service, Pineville, LA.
The successful management of southern pine forests requires a thorough knowledge of the biological and ecological factors regulating them. Insects are an important component of forest ecosystems; therefore, their ecological roles must be considered. And if forest resource management goals are to be optimized, then the negative economic and ecological effects of pests must be minimized, i.e., pests must be managed. In order to develop specific pest management practices that can be incorporated into total resource management, it is critical that the prerequisite research be properly conceived and carried out. A characteristic of integrated pest management (IPM) research programs is their system concept for structuring research and development activities (Waters and Stark, 1980).
The systems framework of Waters and Ewing (1974) has been used to organize and plan ESPBRAP research (Coster 1978). This system has four research and development subsystems (fig. 11-1): insect population dynamics and epidemiology, plant population (forest stand) dynamics, impacts on resource values and management objectives, and treatment strategies. Each subsystem is complex and requires a coordinated research plan. The forest resource manager is less concerned with the research components and is primarily concerned with information and procedures to help him make proper decisions on SPB prevention and suppression. Research to develop decisionmaking models for the resource manager is termed benefits/cost integration. Primary linkages and information flows between the components are shown by the heavier arrows, and feedbacks are indicated by the lighter arrows.
Figure 11-1 – Model structure of an insect pest management system, with research
and development components and the action sequence. (From Waters and Ewing 1974).
Research and development activities provide input to an operational pest management system, which, in turn, is a part of overall forest resource management. An objective of ESPBRAP was to develop operational integrated management systems for SPB (Leuschner et al. 1977). The bottom line of such programs, from the resource manager’s viewpoint, is improvement in his decisionmaking capability. Benefits from improved decisionmaking include (1) more efficient and effective utilization of financial resources for SPB control, (2) less disruption of long-term management plans and activities through timely prevention or remedial control actions, (3) more sound management plans through inclusion of SPB considerations into proposed forest practices (thinning, harvesting, species conversion, etc.), (4) a more accurate description of SPB damages, and (5) a reduced need for costly, short-term crisis response activities that do not alter the basic causes of beetle outbreaks.
The preceding chapters have presented, in considerable detail, the status of southern pine beetle research as of 1980. This chapter briefly summarizes the results from ESPBRAP research as they relate to the four research and development components of an IPM system. Such a summary, along with an earlier one (Coster 1978) and Chapter 12 on recommendations for future research, is a status report on research and development that is the basis for integrated SPB management.
SPB Population Dynamics
Population dynamics is the study of changes in numbers of an organism in space and over time. Understanding the dynamics of both the SPB and its host tree is, therefore, the foundation of an integrated management system. Waters and Stark (1980) point out that "…whereas some immediate or short-term control decisions can be made on the basis of current pest population levels and damage, pest management encompasses a greater timespan, and more detailed knowledge of the factors affecting the dynamics of specific pest populations is needed to develop the interactive predictive models for input to the stand dynamics and treatment components."
Population dynamics of the southern pine beetle has been described at three levels: within individual trees, within individual spots, and throughout the forest (Chapter 5). Methods have been developed for sampling SPB populations at all three levels and for predicting population trends (Chapter 6). The Arkansas and TAMBEETLE population dynamics models are suitable for predicting timber loss and rate of development for individual spots. Two regression models for predicting spot growth have also been formulated. Predictions of longer-term, areawide populations and damage can be made with the DAMBUGS and FRONSIM simulators. The subject of modeling SPB populations has been discussed in detail in the proceedings of an ESPBRAP-supported symposium (Stephen, Searcy, and Hertel 1980).
Forest Stand Dynamics
Accurate descriptions of the dynamics of southern pine stands are necessary in pest management because management decisions are based on forecasts of the effects of SPB on growth, yield, and distribution of the stands. Stand dynamics models must operate within the framework of the pest management system and also be compatible with the overall forest management scheme in order to forecast effects of a variety of silvicultural practices.
Growth of loblolly pine stands may be simulated using PTAEDA (see Chapter 7). There are two variations of the model, one for plantations and another for naturally seeded stands. The models simulate stand growth with or without mortality and can also be used to estimate growth and yield in general. The several stand-rating systems (Chapter 8) relate soil, site, and stand conditions to relative hazard of stands to SPB attack. Some of the models also estimate the probability (incidence) of SPB outbreaks in given hazed types (see Chapter 6).
This component of IPM is much more complex than a simple array of tactics that have been shown, at one time or another, to cause significant SPB mortality. In the first place, both direct and indirect control approaches are part of this component. And the pest manager needs the capability to predict the potential biological and ecological outcomes of treatment alternatives under a range of hypothetical conditions. He must also be able to assess the benefits and costs of each treatment. Cost includes not only the direct costs for applying the treatment, but also the costs of possible environmental effects on the resources. These costs may be very difficult to assess for preventive (long-term) treatments.
Direct controls for use against the beetle include lindane and chlorpyrifos insecticides, salvage removal of infested material, cut-and-leave, and pile-and-burn (see Chapter 10). In the forest, only salvage and cut-and-leave are currently used to an appreciable extent.
Silvicultural recommendations for reducing southern pine beetle losses have been developed from the site-stand data (see Chapter 4) and from experience in managing southern pines. Hazard ratings (Chapter 8) can be used to assign treatment priorities to stands highly susceptible to beetle attack. Recommendations for promoting tree and stand resistance and protecting sites in each of the major geographic subregions of the South are available (see Chapter 9). Because of the long timespan needed to evaluate their effectiveness, the efficacy of silvicultural approaches in preventing SPB losses is unknown.
Methodologies are available to assess efficacy of proposed treatments on southern pine beetle populations and on timber damages (Coster and Searcy 1979).
Impacts on Resources
Impact assessment gives the resource manager measures of values. Impact and damage (injury) should not be equated. Impact was defined in Chapter 7 as any change in the forest caused by an insect population. The impact may affect flora and/or fauna. SPB damage, therefore, may result in positive, negative, or no impact, depending on the conditions.
From an economic standpoint, the southern pine beetle most severely affects the timber resource. This impact can be simulated for wide areas by using FRONSIM (see Chapter 6). For individual spots, the spot-growth models previously mentioned under SPB population dynamics will provide estimates of timber loss. All of the spot and areawide models can give estimates of timber volume killed, number of spots, and number of dead trees. Economic guidelines (Chapter 7) also describe salvable values from beetle-killed timber. Economic impacts on timber for large areas can be calculated from the Timber Benefits Analysis Program (TBAP) using local volume tables, volume of trees affected, stumpage values, and acreages affected.
The economic impacts of infestations on recreation, hydrologic, and grazing resources can be measured, but impacts on wildlife populations and on wildfire occurrence can only be qualitatively estimated. Esthetic impacts can be quantified with a relative scale, but economic values for the impacts cannot be derived (see Chapter 7).
Combined aerial and ground sampling plans, an electronic radio navigation system, and a computer-aided infestation accounting system all materially improve the efficiency and effectiveness of gathering basic timber loss data (Chapter 6).
Before proper decisions can be made, alternative courses of action must be identified and their economic and environmental consequences spelled out. An areawide SPB outbreak, with all of its political, economic, and ecological complexities, requires thorough decision analyses. Benefit/cost analysis is essentially the process by which alternative actions and their consequences are presented for the resource manager’s decision.
The foundations for an IPM system for the southern pine beetle are in place. And although most land managers and pest managers would agree that there is need both for refinement of existing information and for additional research, the existing information can be used to markedly improve current management decisions for SPB. This improved support information will enable resource managers to better plan SPB prevention and suppression activities to meet the overall objectives of forest resource management plans.
There are several characteristics of southern forests and forest management that influence development of SPB management systems. More than 70 percent of the southern forest lands belong to small, private, nonindustrial owners. Responsibilities for insect control and management activities reside in a variety of State, Federal, and private organizations. In many cases, there are inadequate numbers of properly trained personnel in these organizations to service integrated SPB management systems.
Southern pine stands are quite dynamic and site and stand conditions are highly variable. Growing seasons are long (220-270 days) and conditions are favorable for overlapping SPB generations each year. The insect itself has a high reproductive potential that results in rapid population buildups. This situation puts pressure on suppression operations to stay current with the outbreak.
These considerations have led to a general ESPBRAP management philosophy regarding the development and implementation of an integrated management system for SPB. The varied ownership and management objectives of southern pine forests; the range of Federal, State, and private policies with regard to pest control activities; the variation in capabilities of pest managers, landowners, and resource managers to gather technical input data; and the wide range of biological conditions in southern pine forests all indicate that an integrated management system composed of tightly linked, computationally interdependent models and submodels would, at this time, be useful to only a limited number of landowners and managers concerned with the SPB problem. Instead, the approach is to develop a series of more or less independent models that are suited to different-sized areas, timespans, and predictive uses (Leuschner 1979). The hierarchy of predictive models is shown in table 11-1.
Results of ESPBRAP research on the various components of an integrated system are still so new that time has not permitted the simulations, validations, and modeling efforts to be thoroughly carried out. These analyses are needed in order to enable proper integration of components into a practical system. But land managers and landowners have immediate needs and, in some areas, a new research finding can be put to use immediately to meet the need adequately.
Thus, the stepwise decision processes now used in forest pest management can be strengthened by indicating where new technology and methodology is appropriate for use by decisionmakers. Such an array of information, when related to the decisionmaking process, is called a decision support system. The general goal of such support systems is to provide resource managers and landowners with tools and information they need to consider alternative means of maintaining beetle-caused damage at tolerable levels, according to their management objectives, on a continuing, long-term basis.
A southern pine beetle decision support system must address both long-term (preventive) and short-term (crisis response) control needs (Coster 1977). One of the real benefits of integrated SPB management will be to put crisis response actions in better perspective with regard to the overall management objectives of a resource manager or landowner. Long-term controls for SPB, primarily silvicultural manipulations, are thought to offer the best possibilities for lowering the incidence and severity of SPB infestations and for reducing the frequency of crisis response actions (Coster 1978). One of the hallmarks of implementation of integrated SPB management will be more emphasis on preventive strategies and a concurrent shift in attention of landowners and resource managers from local (spot) populations to areawide populations.
|Model Number||Area Covered||Information Predicted||Use of Prediction|
|Impact over next
5 - 50 years
|Estimate benefits of long-
term prevention programs
|Impact next year||Plan control activities
for coming field season
|Impact next month||Plan field activities|
|Spot growth if
activities on spot
1 Wide areas are multicounty or forest survey unit-sized areas.
It should be made clear that a decision support system is only an information-gathering and –collating system. The resource manager or landowner will bear the final responsibility for management decisions. The basic questions that he must answer are (1) Is the long-term and/or short-term level of damage detrimental to my management/ownership goals? (2) Of the long- and short-term SPB management options, which are most suitable for the current situation?
The components of a southern pine beetle decision support system will include:
The landowner/resource manager would normally supply information on (1) and (3) while the pest management specialist would be primarily responsible for providing information on the other items. Both the manager and the specialist would contribute information on (4).
The importance of landowner/resource manager input to SPB management decisions should be emphasized. Mangers bear responsibility for the final decisions and must, therefore, spell out clearly the time, space, and economic limitations that their overall resource management plans may place on SPB management actions. Failure to do so may result in either inadequate information for decisionmaking, or excessive costs in obtaining information.
Implementation of a decision support system that is based on state-of-the-art ecological and economic data and that provides for modeling and simulation of management options, is the first step in putting into practice an integrated SPB management system A functional decision support system must provide information to the forest manager at the proper junctures during deliberations on SPB control/management. In other words, the support information must be supplied in proper sequence — and in the proper format. The support system must also indicate who is responsible for information gathering, who is responsible for simulations and analyses, and, if all decisions are not made by the same manager, who is responsible for making the decisions.
The steps in developing SPB decision support systems are:
An outline of a rather complete SPB decision support system is shown in figure 11-2. To the left is the landowner/resource manager’s decisionmaking process as presented by Freeman (1978). It serves as the template against which the decision support system is juxtaposed. The support system includes both support persons and support tools (information, models, procedures, guidelines, etc.). Decision support persons are the "keepers" of the system, responsible for its "care and feeding."
Figure 11-2 – Decision process and decision support system for SPB management.
Decisions are reached at three places in the process. At any decision level, further deliberation and input from the decision support system may be terminated. Decision A often is made by field or survey personnel when they assess spot sizes and spot activity. The decision may simply be to ignore the beetle activity. Early decisions also may concern the need to evaluate site and stand conditions for purposes of improving surveillance and monitoring activities or for selecting areas in which to concentrate preventive practices.
Decision B is reached after considerable input from the decision support system along with careful consideration of management objectives. If at this junction the manager/landowner decides that his objectives are being, or will be, significantly affected by the beetle activity, then a great deal more information will subsequently be required from the decision support system. The importance of accurate evaluations (step 3) and of accurate statements of land management goals (step 4) is apparent. Any error at juncture B can be costly.
Considerable information support is also needed for decision C. The decision at this point may be to defer action. Perhaps, under the conditions, none of the controls is cost effective, or perhaps the environmental/social consequences of all actions are untenable. A decision to undertake preventive or suppressive actions may carry with it the selection of more than one option. For example, salvage along with the initiation of stand thinnings may be selected in order to simultaneously control existing infestations, recover some of the loss, and minimize future outbreaks.
At step 12, the resource manager reexamines forest management plans for the affected unit(s) and makes adjustments in view of the preceding decisions. Perhaps the selection of silvicultural option shifts age class distributions, species composition, and product mix. If so, inventories and harvest schedules must be revised. And all of these changes could, in turn, have future effects on wildlife habitat, esthetics, and other resources.
And finally, the decision process culminates with implementation of suppression tactics and/or preventive strategies. Implementation leads to an entire new set of logistical decisions. Evaluation of the actions taken, and the decisions that led to them, are also part of the pest management decisionmaking process (step 13). Posttreatment evaluations provide feedback for improvement of the decision support system and may be required where public funds are involved.
The decision process and support system in figure 11-2 is an outline and is not intended to apply to all management situations. With such an outline, however, pest management specialists and land managers can tailor a support system for specific management goals.
One of the important contributions of such data-based systems is that the simulations and guidelines can be used to examine combinations of prevention and suppression actions before SPB outbreaks occur in a forest. By varying such factors as level of beetle activity, hazard ratings, and resource values, the manger can better plan where preventive strategies may be most effective, when beetle activity has reached levels requiring suppression actions, and what suppression and prevention actions will be most appropriate. In other words, the resource manager can use the tools of the decision support system to arrive at an SPB prevention and suppression plan that is ecologically and economically rational. Such prevention and suppression plans clearly place SPB management within overall forest management planning, displacing the current "wait-and-see" policy toward SPB with a "look-ahead" policy.
Despite the advantages and benefits that will accrue from better management decisions concerning SPB control, we can expect problems in getting landowners and forest managers to adopt the new practices. The experience of technology transfer experts indicates that it often takes many years to incorporate new scientific developments and technology into practice. The distant planning horizons used in forest management suggest that incorporation of new SPB management options, especially long-term preventive actions, into forest management plans will occur slowly.
The challenge of implementing decision support systems comes down to the need for setting in motion an aggressive technology transfer process. During the final 2 years of ESPBRAP, a broad-based technology transfer (applications) effort was begun. An eight-step technology transfer process was defined (U.S. Department of Agriculture Forest Service 1979):
A task force of forest managers, pest managers, and researchers recommended priorities for allocation of ESPBRAP funds to support technology transfer (U.S. Department of Agriculture Forest Service 1979). Technology transfer teams were constituted for eight applications areas: silvicultural practices and stand-rating systems, utilization of SPB-killed timber, socioeconomic guidelines, insecticides and improved spray systems, sampling methods and predictive models, aerial survey and navigation systems, behavioral chemicals, and integrated management strategies.
The task force gave low priority to immediate need for technology transfer activities in the integrated management strategies area, reasoning that through the end of ESPBRAP there was greater need for continued research and development. The task force recognized that technology transfer activities in this area should begin to increase rapidly, however, in 1981.
Decision support systems, and the resulting prevention and suppression plans, will be developed for several classes of forests (e.g., industrial, private nonindustrial, high-use recreation, low-use recreation, urban, etc.). Technology transfer activities will be somewhat different for the several types of ownerships because of their different concerns and/or management objectives. Indeed, even the complexity of the decision support systems will be quite different for different classes of ownership.
Opportunities for reducing SPB impact by implementing SPB management appear to be best in those forests where the beetle is a chronic problem and where well-developed forest management plans have been implemented. These forests include those that are intensively managed for timber production and/or for multiple products, e.g., National Forests and industrial forests. Implementation of successful SPB management by several such innovative organizations would serve to demonstrate the effectiveness of the new methods to other forest landowners.
Who has the responsibility for encouraging forest landowners to implement new SPB management practices? Pest management specialists in State forestry organizations, cooperative extension services, the U.S. Forest Service, and the universities must take this leadership in technology transfer. The primary need of potential users is for technical assistance. Pest management specialists are in the best position to meet that need.
ESPBRAP has served as the vehicle to bring a diverse group of researchers and specialists from many disciplines together to work on a common problem — the southern pine beetle. As a consequence, existing information on SPB was reexamined, up-to-date methodology in biology, engineering, and mathematics was employed in new investigations, and a considerable amount of information was acquired for improving SPB management.
It would be remiss to leave the impression that the quality and quantity of existing information is adequate for all management situations. It is not. Chapter 12 points out future needs. Many of the decision support tools have not been validated and refined for use in other areas and/or under other conditions. Resource managers must provide feedback (step 13, fig. 11-2) to pest management specialists and researchers so that the models and guidelines can be improved.
Further analysis and synthesis of the large amount of knowledge on SPB is needed to properly design integrated SPB management and treatment strategies. But landowners and forest managers can incorporate the improved information that now exists into their pest management decision processes. These improved decision support systems, which might be called "first generation SPB management systems," can markedly improve today’s pest management decisions.
Developed by the University of Georgia Bugwood Network in cooperation with USDA Forest Service - Forest Health Protection, USDA APHIS PPQ, Georgia Forestry Commission, Texas Forest Service
and the Pests and Diseases Image Library - Australia
Last updated August 2018
www.barkbeetles.org version 2.0