Summary

Between the 18th century and the first half of the 20th century, forest ecosystems in eastern North America lost an iconic tree species, the American chestnut, to two introduced pathogens. The loss of the chestnut (an estimated 4 billion trees) to chestnut blight and root rot caused adverse effects on other species and disrupted livelihoods dependent on chestnut products. During the same time period, white pine blister rust decimated white pines in the western United States. In the early 21st century, most eastern North American species of ash began succumbing to an insect pest introduced from Asia, the emerald ash borer. Losses in the form of timber value and removal of urban trees made the borer a costly forest pest. Some species of native bark beetles have killed billions of trees since 1990 in the West. These are just a few of the North American tree species that have been functionally lost or are in jeopardy of extirpation due to insect pest and pathogen outbreaks. The Forest Service of the U.S. Department of Agriculture (USDA) estimates that 32.9 million hectares (81.3 million acres)—that is, almost 7 percent of all forested¹ or treed² land in the United States—are at risk of losing at least 25 percent of tree vegetation between 2013 and 2027 due to insects and diseases (see Figure S-1).

Outbreaks of native pests are common disturbances in forests and can be integral to renewing forest ecosystems and maintaining biodiversity. However, ecosystems can be seriously disrupted when a nonnative, invasive pest³ is introduced or when native pests increase their geographic range or become more virulent because of external drivers such as climate change. Massive, synchronous die-offs threaten the survival of tree species and negatively affect ecosystem services, such as water filtration, soil erosion prevention, carbon sequestration, livelihoods, and social values.

Effects of pest outbreaks could be mitigated through preventing arrival of invasive species, site management practices, biological control agents, the use of genetic resistance naturally present in

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¹ Forested land contains at least 10 percent tree canopy cover.

² Treed land is an area with measurable tree presence, including urban areas and land in the Great Plains with trees that does not meet the definition of forested land.

³ The general term pest includes both insects and pathogens that cause damage to forests.

target species, or biotechnological modifications to confer resistance in the target species. As of 2018, although research on incorporating resistance to insects or pathogens via biotechnology was being conducted in some forest tree species such as the American chestnut and poplar hybrids, no such resistant genotypes—created with the intent to spread resistance into a forest population—had been planted in a North American forest. Given the threats to North American forests, USDA,⁴ the U.S. Endowment for Forestry and Communities and the U.S. Environmental Protection Agency (EPA), asked the National Academies of Sciences, Engineering, and Medicine to convene a committee of experts to investigate a number of questions related to the potential for biotechnology to be used in trees to address forest health (see Box S-1). The committee was not asked to examine the potential for biotechnology to reduce threats to forest health by altering the pests affecting North American tree species.

THE COMMITTEE’S PROCESS

Members of the Committee on the Potential for Biotechnology to Address Forest Health were appointed by the president of the National Academy of Sciences for their expertise in a variety of disciplines pertinent to the study’s task. To help it address that task, the committee held information-gathering meetings between December 2017 and April 2018. It heard from 43 speakers during 3 in-person meetings and 10 webinars. The committee also reviewed the scientific literature and welcomed comments by members of the public. The committee used this information-gathering process to define forest health and to shape its report (see Box S-2). The conclusions and recommendations included in the summary are based on the main body of the committee’s report.

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⁴ The specific sponsoring agencies within USDA were the Agricultural Research Service, Animal and Plant Health Inspection Service, National Institute of Food and Agriculture, and Forest Service.

THREATS TO FOREST HEALTH FROM INSECT PESTS AND PATHOGENS

Since the 1600s, around 450 species of insects and at least 16 species of pathogens have been introduced and become established in continental U.S. forests. Of those, 62 insects and all of the pathogens have been classified as high-impact species, causing some combination of tree mortality, canopy thinning, growth loss, defoliation, and decreased reproduction or regeneration. Some of these introductions have had devastating consequences in North American forests; impacts have ranged from temporary declines in population productivity to the functional extirpation of an entire species, as was the case with the American chestnut.

With warmer climate, many native and nonnative insects are colonizing regions that previously had been unsuitable. Forecasts of future climate indicate likely changes in pathogen overwintering survival, changes in host susceptibility to pathogen attack due to other stressors (e.g., drought or storm damage), or changes of life cycles of insects that disperse pathogens. Changes in climate are also predicted to increase the frequency and magnitude of pest outbreaks in the future.

The effects of pests on individual trees have cascading impacts on populations, reducing reproduction and survival. Local extirpation of the tree species and extinction of species dependent on it may result. For example, five moth species went extinct with the loss of the American chestnut. Such species-specific effects can change community assemblage and structure, and thus, ecosystem function.

Conclusion: Healthy forests provide valuable ecosystem services to humans.

Conclusion: The health of North American forests is threatened by the introduction and spread of nonnative insects and pathogens and the epidemics of native pests exacerbated by environmental stress due to climate change.

Conclusion: Tree species in forest ecosystems, tree plantations, and urban landscapes across North America are threatened by insect pests and pathogens.

Conclusion: Many forest tree species are threatened by more than one insect pest or pathogen.

Conclusion: As the frequency of insect and pathogen outbreaks increases, many forest tree species are in jeopardy of being lost from the landscape, resulting in changes to ecosystem services.

MITIGATING THREATS TO FOREST HEALTH

There are multiple options for dealing with forest pests, but feasibility and success vary widely. For nonnative insects and pathogens, the first line of defense is preventing their introduction. When introduced pests have become established or native pests are expanding their range or increasing in virulence, chemical or biological control can suppress pest populations in some cases, but these approaches are often not acceptable to the public, effective, or timely. Other management practices such as quarantines or thinning tree stands may help minimize a pest outbreak but are most likely insufficient.

Trees genetically resistant to a pest have the ability to minimize or overcome the damaging effects of a pest. Genetic resistance can be accomplished through selective breeding or biotechnology. The first step in selective breeding is to determine whether genetic resistance exists within the affected species population. Finding suitable parent trees can be difficult, and even with resistant parent trees, not all of the progeny will be resistant. Evaluating the durability of resistance will also be paramount because trees will be on the landscape for decades. Resistant progeny will need to be

propagated in greenhouses or seed orchards to create sufficient resistant genotypes for restoration and reforestation.

To use biotechnology to confer resistance, the first step is to identify genes for modification, introduction, or silencing. If a gene is not already in hand, then a gene discovery process is required. This step has been hindered due to trees’ large size, long generation time, and (in the case of conifers) immense genomes. Another problem is that forest trees have high levels of heterozygosity due to their large population sizes and outcrossing breeding systems, which complicates genome assembly and modification.

The second step is production of trees containing the desired gene sequence. Biotechnology tools such as transgenesis and genome editing, used to introduce a desired change to gene sequence, are followed by tissue culture protocols, in which the desired gene can be introduced into a single cell. Then whole plants are generated from the transformed cell by regeneration of roots and shoots from disorganized callus tissue. However, many species of trees remain recalcitrant to cell culture and regeneration. Even when possible, the regeneration of a plant from a single cell may not produce an individual that has the desired genetic change in every cell.

Thus, using biotechnology to introduce traits to address forest health has its challenges. Nonetheless, biotechnological research to introduce or modify traits in trees has been explored in a number of tree species since the late 1980s. For a forest health threat, the most advanced research has been conducted on the American chestnut. A wheat gene encoding the enzyme oxalate oxidase (OxO) has been inserted into the chestnut genome using transgenesis. Oxalic acid generated by the chestnut blight weakens cell walls, enabling other fungal enzymes to degrade the wall and cell membranes, killing the cell. Widespread cell death eventually girdles the tree. The OxO enzyme expressed in transgenic chestnut converts oxalic acid to carbon dioxide and hydrogen peroxide, thereby conferring on the tree genetic resistance to the blight.

Conclusion: Substantial literature supports the need for sustained investment in prevention and eradication as the most cost-effective and lowest impact approaches for managing introduction of nonnative insect pests and pathogens.

Recommendation: Investment in effective prevention and eradication approaches should be the first line of defense against nonnative species in efforts to maintain forest health.

Conclusion: Any single management practice alone is not likely to be effective at combatting major pest outbreaks.

Recommendation: Management for forest health should make use of multiple practices in combination to combat threats to forest health.

Conclusion: A variety of biotech and nonbiotech approaches have been and will be developed to address insect pest and pathogen threats. The time line for use of these tools in management activities for forest trees and forest health will depend on a number of factors, but the biology of the species involved (both tree and insect or pathogen) and the environments in which the tree species exist will have a major influence on effective mitigation.

Conclusion: Many tree species have some degree of resistance to particular native and nonnative pests that may be harnessed to combat infestations and epidemics.

Recommendation: Entities concerned about forest health should devote resources to identifying resistant trees within a population that have survived a pest outbreak. Research to understand

the role of resistance in coevolved systems from the perspective of a global host–pest system, where the nonnative pathogen or insect originate, would help guide efforts in North America.

Conclusion: Using biotechnology to introduce resistance to threats in forest trees has been hampered by the complexity of tree genomes, the genetic diversity in tree populations, and the lack of knowledge about genetic mechanisms that underlie important traits. However, recent technological developments have improved functional genomic tools, facilitating the potential for biotechnology to help address forest health problems.

Recommendation: More research should be conducted on the fundamental mechanisms involved in trees’ resistance to pests and adaptation to diverse environments under a changing climate.

Conclusion: The time it takes to identify resistance in an affected population, breed resistant seedlings, and plant resistant seedlings in the field can vary from a few years to multiple decades, depending on the species. Incorporating resistance via biotechnology into a tree species is also a lengthy process, the duration of which varies by species.

Recommendation: Sufficient investment of time and resources should be made to successfully identify or introduce resistance into tree species threatened by insects and pathogens.

CONSIDERATIONS RELATED TO THE USE OF BIOTECHNOLOGY IN FOREST TREES

Any intervention to address forest health involves consideration of associated ecological, economic, social, and ethical issues. Some of these considerations are unique to biotechnology, but others are applicable to any intervention.

Several ecological considerations arise in evaluating the use of biotechnology to maintain or improve forest health. They include whether there will be potential gene flow from the biotech tree to relatives and, if so, whether there will be an effect on other species in the environment. Additionally, interspecies gene flow, via horizontal gene transfer or hybridization, could also occur. Genetic fitness of modified trees will be critical because the intent of biotech trees is to recover species over large temporal and spatial scales. Furthermore, even if a biotech tree is genetically fit and able to convert its resistance to subsequent generations, it will not become established in a forest if it is not competitive in the ecosystem.

Genetic variation in trees also needs to be considered in restoration efforts so that modified trees are suited for the environment in which they are planted. An important difference in forest trees versus agricultural uses of biotechnology is that a focus on recovering forest species requires incorporating the specific genetic change while retaining the breadth of genetic diversity in forest populations. This diversity permits the species to continue to evolve under changing abiotic and biotic conditions. In particular, understanding the patterns of radiation out of the glacial refugia (i.e., geographic regions where flora and fauna survived during the ice ages and later recolonized postglacial habitats) and how that has shaped the standing genetic variation in response to past climates is important when choosing genetic backgrounds against which to deploy biotechnological solutions to climate or pest mitigation.

Trees, once planted and maturing, can provide both public and private benefits. Public benefits are those that cannot be exclusively captured by an individual or a firm but are shared across many people and communities. The costs of development of a biotech tree will be incurred up front and the benefits will follow years later. Such a difference in the timing makes investment with a

long time horizon problematic. Compared to the private sector, the public sector can have greater patience when significant public benefits are forthcoming. The economic argument for a public-sector role also arises out of the likelihood that the private sector will not invest in the protection of forest health because it cannot fully capture the benefits that may accrue.

Public opinion research suggests that people generally have positive attitudes about the use of biotechnology in forests, although they often prefer nonbiotech interventions if given the choice. In addition, some biotechnological interventions (e.g., cisgenic or within-species interventions) are sometimes preferred by the public over others (e.g., transgenic or between-species interventions). However, many people lack detailed knowledge of these interventions, such as the processes used in any intervention. As various publics increase their familiarity with this topic, attitudes, norms, and perceptions of risks and benefits may change. Societal responses are highly dynamic, contextual, and varied in their intensity.

Developing biotechnology for use in trees and forests raises a range of social and ethical considerations. Some directly relate to the provisioning of ecosystem services, including the perceived benefits to people and the environment, but others include intrinsic value, wildness, broad social influences, and social justice concerns.

Biotechnology intended to influence and alter the forest could be interpreted as a form of human control of a forest ecosystem. Transgenic or genome-edited trees, planted and possibly managed and monitored by humans, could be understood to reduce wildness. The use of biotechnology is also a human intervention in the “natural” evolutionary trajectory of the forest. Although the use of biotechnology may promote forest health, it may be perceived as diminishing the forest’s wildness. On the other hand, threats to forests that biotechnology may counter are predominantly of human origin (e.g., invasive pests transported by people and native pests extending their range because of human influences on climate). Given that these changes are also signs of human influence, forest wildness may already be seen as reduced. Doing nothing to counter such threats may result in the loss of populations or entire species, with significant effects on forest ecosystems that also mean a loss of wildness. Other practices that might address forest health, such as selective breeding, pose similar threats to wildness because they involve the selection of genotypes, the decision to plant trees, and continued monitoring of the trees.

Conclusion: Trees with resistance introduced via biotechnology will have to survive until maturity and reproduce in order to pass resistant traits on to the next generation.

Recommendation: Research should address whether resistance imparted to tree species through a genetic change will be sufficient to persist in trees that are expected to live for decades to centuries as progenitors of future generations.

Conclusion: The importance of managing and conserving standing genetic variation to sustain the health of forests cannot be overstated.

Recommendation: The deployment of any biotechnological solution with the goal of preserving forest health should be preceded by developing a reasonable understanding in the target species of (a) rangewide patterns of distribution of standing genetic variation including in the putative glacial refugia, if known; (b) magnitude of local adaptation (gene × environment relationships); and (c) identification of spatial regions that are vulnerable to genetic offset.

Conclusion: The public sector will be best positioned to lead development of biotech trees because of the public-good aspect of forest health and the intention for the spread of a biotech tree through a forest ecosystem.

Conclusion: The relatively long time required for the development of a biotech tree may adversely affect the incentive for both private- and public-sector investment.

Conclusion: Few studies of public attitudes toward biotechnology to address forest health threats have yet been carried out in the United States. However, there has been a small handful of studies on the topic, especially in Canada and Europe. The limited data indicate that while some individuals and groups are very concerned about possible deployment of biotechnology in forests, attitudes toward the uses of biotechnology examined in these studies are somewhat positive, especially where threats to forests are severe.

Conclusion: Existing research indicates that public knowledge and understanding about the use of biotechnology in forests is low, suggesting that current attitudes may be unstable and liable to change with more information. The power of such information to influence attitudes is mediated by the perceived trust of the sources of information, deliberation about the topic, and the alignment of new information with deep value orientations.

Conclusion: Some important ethical questions raised by deploying biotechnology in noncommercial forests fall outside any evaluation of changes in ecosystem services.

Recommendation: More studies of societal responses to the use of biotechnology to address forest health threats in the United States are needed. Such studies might investigate (1) the responses of different social and cultural groups to the deployment of biotechnology in forests, (2) the stability and consistency of attitudes toward different applications of biotechnology in a range of circumstances, (3) differences in attitudes toward biotechnology strategies (e.g., cisgenesis, transgenesis, genome editing), (4) the relationship between deeper value orientations and attitudes toward biotechnology, and (5) how people consider trade-offs between values such as wildness and species protection.

Conclusion: The use of biotechnology for forest health, especially in noncommercial forests, raises broad questions about the social impacts of technological change on society, in particular how conservation is understood and practiced, and how far biotechnological interventions presage a change to more interventionist management of forests.

Conclusion: The use of biotechnology for forest health raises social justice questions, both in terms of the distribution of risks, harms, and benefits across individuals and groups through time and in terms of the procedures used to make decisions about whether, when, and where to deploy the technology. Indigenous communities may be particularly affected by these decisions. Given the longevity of trees, the use of biotechnology for forest health (or the decision not to use it) will have significant impacts on future generations.

Recommendation: Respectful, deliberative, transparent, and inclusive processes of engaging with people should be developed and deployed, both to increase understanding of forest health threats and to uncover complex public responses to any potential interventions, including those involving biotechnology. These processes, which may include surveys, focus groups, town hall meetings, science cafés, and other methods, should contribute to decision making that respects diverse sources of knowledge, values, and perspectives.

INTEGRATED IMPACT ASSESSMENT FRAMEWORK

When assessing the impact of a pest threat on forest health, evaluating the effect of that threat on forest processes and cultural and spiritual values provides the basis for assessing how the provision of ecosystem services may change. The risk of loss of ecosystem services over part, or all, of a species’ range is weighed against the potential to recover ecosystem services with and without the biotech intervention. Such a framework could be used to evaluate any forest health intervention, including the use of selectively bred trees.

When considering impact assessment for the use of biotechnology in forests, links between specific forest protections and their effects on important ecosystem services should be made explicit. Existing EPA guidance on classification and measurement of ecosystem services provides a useful frame that can be modified to address the range of services provided by introduction of pest-resistant trees. The advantage of bringing ecosystem services into impact assessment is that it makes possible the inclusion of a broader range of values and the connection between the protection of forests and human well-being clear for the public, stakeholders, and policy makers.

At the time the committee was writing its report, few biotech trees developed to address forest health had been planted in field conditions; those that had were still in field trials. Because of the length of time until tree reproductive maturity and long life span of most trees, collecting data for an impact assessment may take years to compile. To help address this issue, data from field trials can be combined with data derived from other types of biotech plant releases to parameterize simulation models to inform impact assessment. Modeling approaches can include gene flow and climatic tolerances. Surveys and stakeholder engagement will help to identify human values and concerns associated with specific products of biotechnology. Synthesis of all available information will aid in making informed predictions of potential risks. Modeling scenarios that include sources of uncertainty will allow quantification of the reliability of the assessments, estimation of the predictive capacity of the model, and identification of data needs.

Coupling adaptive management with impact assessment would allow adjustments to be made to decisions about the development and deployment of biotech trees for forest health as data are collected. However, the ability to make adjustments based on new knowledge is complicated by the U.S. regulatory system, which generally does not permit the flowering of biotech trees. Without flowering, it is difficult to gather data on gene flow and other parameters to inform an impact assessment framework. A hierarchical regulatory system that assigns biotech trees to different tiers of risk would be more amenable to adaptive management. If data on gene flow and impacts on ecosystem services were simultaneously collected, they could be used to refine simulation models to obtain more precise prediction of potential outcomes. These analyses could then be used to propose increasingly larger environmental releases until the trees are either discontinued or deregulated by the relevant oversight agency. This stepwise approach may be the only practical way to obtain data on gene flow and impacts at the spatial and temporal scales that are needed for proper impact assessment for biotech trees.

Conclusion: An integrated impact assessment framework that combines ecological risk assessment with consideration of ecosystem services would provide a way to evaluate impacts of introduction of a biotech tree both on the forest functions and on the ecosystem services provided. Societal and cultural values need to be incorporated into this approach.

Recommendation: Federal agencies should continue efforts to improve the incorporation of all components of ecosystem services into the integrated impact assessment.

Conclusion: Field trials are an important tool to gather data on biotech trees in terms of gene flow, the durability and effectiveness of resistance, seed generation and dispersal, genetic fitness, and some impacts on the ecosystems into which the trees are planted.

Conclusion: Modeling efforts will be essential to address the large spatial and temporal scales and stochastic nature of biotech tree impact assessment.

Recommendation: Modeling and other approaches should be developed to address questions about biotech tree gene flow, dispersal, establishment, performance, and impact that are precluded where flowering of field trial material is restricted.

Recommendation: Models for tree biotech impact assessments should identify, quantify, and account for sources of uncertainty.

Conclusion: Iterative decision making is required, such that impact assessments are continually modified with improvements in knowledge gained through on-the-ground experience with biotech tree development, testing, and deployment because of the uncertainty associated with predictions of the impacts of release of biotech trees into minimally managed or unmanaged environments.

Recommendation: An adaptive management approach to forest health should be used to ensure continued learning and address impacts to both the environment and society.

Recommendation: Impact assessment should be a continuous and iterative process.

U.S. REGULATORY SYSTEM AND FOREST HEALTH

Biotech trees developed to address forest health are regulated under the same statutes and regulations as any biotech plant. The Coordinated Framework for the Regulation of Biotechnology, established in 1986, specified that oversight of biotechnology products would be carried out using existing legislative statutes. Under the framework, up to three federal agencies—USDA, EPA, and the U.S. Food and Drug Administration—are most likely to have a role in the regulatory oversight of a biotech tree developed to address forest health.

The statutes utilized by these agencies do not consider most aspects of forest health in analyzing the safety of a biotech plant. The different statutes grant each agency authority to regulate specific products and activities or uses of those products, not the process by which the products are produced. The application of the Coordinated Framework to specific products means that biotech trees and plants may be regulated by zero, one, two, or three or more agencies.

Forest health also is not considered in the regulation of nonbiotech products designed to address forest health problems. The assessments or reviews conducted for these management options do not do a better job of incorporating forest health and ecosystem services into their analysis than the assessments conducted for biotech trees.

Conclusion: The current regulatory framework for biotech plants applies to biotech forest trees and does not impose any additional or different requirements for trees than other plants.

Conclusion: The current regulatory framework that applies to biotech trees that are developed to address forest health encapsulates very few elements of the committee’s comprehensive definition of forest health.

Conclusion: If a regulatory agency is required to comply with the National Environmental Policy Act (NEPA) when regulating a biotech tree, then some components of forest health will be analyzed.

Conclusion: USDA only carries out a NEPA analysis—environmental assessment and/or environmental impact statement—for a small subset of biotech trees.

Conclusion: As is the case with other biotech plants, some biotech trees could become commercial products without any oversight by the three regulatory agencies.

Conclusion: There are mechanisms in place to alert neighboring countries about biotech forest trees that could enter their territory, but biotech trees could migrate across a national border without notice if the biotech tree is not regulated in the country of origin.

Conclusion: Forest health also is not considered in the regulation of nonbiotech products designed to address forest health problems, such as biological control agents, pesticides, and assisted migration.

Conclusion: Some federal agencies have policies for the assisted migration of trees and/or the planting of biotech trees on federal lands, while private landowners can plant nonnative and biotech trees without violating any federal laws or policies.

Recommendation: Regulatory agencies should explore ways to incorporate into their regulatory oversight responsibilities the ability to assess the impact on ecosystem services for both biotech and nonbiotech products developed for improving forest health.

MOVING AHEAD

Biotechnology has the potential to help mitigate threats to North American forests from insect pests and pathogens through the introduction of pest-resistant traits. However, it also presents some challenges. The necessary genetic changes to achieve resistance are often not easy to identify and are challenging to incorporate. Tree genomes are complex, and much remains to be learned about the genetic mechanisms that underlie important traits. Additionally, unlike the modification of agricultural crops through biotechnology—in which a genetic change is introduced to and propagated in an individual variety—genetic changes in trees for forest health purposes need to be introduced into diverse breeding populations so that tree species can respond to biotic and abiotic stress over time and across their spatial distributions.

Furthermore, the effectiveness of biotechnology at mitigating forest threats needs to be assessed on many fronts. In addition to evaluating the utility of the resistance trait in protecting a tree species, the modified tree needs to be tested for viability in the diversity of environments in which it will live. An assessment of the effects of the tree on other species in the environment is also important, as is a comparison of using biotechnology to address the threat versus other mitigation tools.

Finally, research and investment efforts need to be made in areas besides biotechnology, including the development of further strategies for preventing the introduction of nonnative insects and pathogens, human capital development in professions related to tree breeding, and social science research, including a conceptual framework for capturing and accounting for the intrinsic value of forests. Such work will benefit the health of forests, regardless of the pest mitigation tools put to use.

Therefore, the committee’s preceding recommendations point toward research and investment on three fronts that would (a) address knowledge gaps about the application of biotechnology to mitigate threats to forest health and (b) improve the utility of biotechnology as a forest health tool:

1. Knowledge about tree genetics related to resistance, specifically investment in identifying resistant trees in populations that have survived pest outbreak and research on the funda

1. mental mechanisms of resistance, existing genetic variation in tree populations, and the durability of resistance.
2. Data and tools for impact assessment, in particular investment in efforts to improve the incorporation of all ecosystem services into integrated impact assessments, to collect data to inform and improve models, and to increase the use of adaptive management to address forest health threats.
3. Management approaches that take into account disciplines beyond biotechnology, including more studies on societal responses to using biotechnology to address forest health, more investment in prevention and eradication efforts of introduced pests, and better efforts at respectful, deliberative, transparent, and inclusive processes of engaging with people to increase understanding of forest health threats and to uncover complex public responses to potential interventions.

Additionally, the committee includes the following recommendations to support a holistic effort to improve forest health with the help of biotechnology.

Recommendation: Public funders should support and expand breeding programs to encompass the genetic diversity needed to preserve tree species essential to ecosystem services.

Recommendation: Investment in human capital should be made in many professions, including tree breeding, forest ecology, and rural sociology to guide the development and deployment of pest-resistant trees.

Recommendation: Studies of societal responses to the use of biotechnology to address forest health threats should be used to help in developing a complementary framework to ecosystem services that takes into account intrinsic values, related spiritual and ethical concerns, and social justice issues raised by the deployment of biotechnology in forests.

Recommendation: Developers, regulators, and funders should experiment with analytical-deliberative methods that engage stakeholders, communities, and publics.