Managing for Healthy White Pine Ecosystems in the United States to Reduce the Impacts of White Pine Blister Rust
Executive Summary
n this report we outline the urgent need for of this disease, from understanding the basic vision, focus, and leadership to manage a biology of the pathogen and its hosts and non-native invasivedisease that threatens identifyingnatural disease resistance in sugar I the stability and survival of white pine pine, western white pine and eastern white pine to ecosystems in 40 of our 50 states. All nine of our developing improved planting stock and initiating native white pine species are at risk and include breeding programs with other species. We now some ofthe oldest, most realize that blister rust is a majestic, and ecologically or permanent resident of North culturally significant pine America. Therefore, our species in the United States. efforts have shiftedtowards White pines play critical facilitatingthe survival of roles in forest development white pine species in the and integrity.Without white presence of the disease and pines these forest minimizing its ecological, communities would be economic and aesthetic altered dramatically. impacts. Historically, white pines thrived because of their This plan is designedto abilityto regenerate in establish direction to restore openings created by fire, white pines where they have outgrow their competitors, been catastrophically and resist many native decimated, to sustain white insects and pathogens. All pines where the rust is species of white pine are present but not yet susceptible at all ages to a devastating, and to plan non-native fungus which mitigating actions when the causes white pine blister rust spreads into areas where rust. it is not yet present. Unless we take a bold and White pine blister rust is scientifically sound caused by a non-native approach, we risk losing a invasive pathogen, Figure 1. Westernwhitepine mortality. significantcomponent of our Cronartium ribicola that native forests, and with it, was introduced to North America ITomEurope considerable irreplaceablebiodiversity,as well as almost a century ago. Despite significantefforts genetic and cultural resources. This effort will to contain it, this fungus has continued to spread require the applicationof existing management (Fig. 1) and may be poised to invade the last tools and continued research and development uninfected white pine ecosystems, includingthe using integrated genetics, pathological, ancient bristlecone pine forests of the Southwest. silvicultural,disease management and ecosystem restoration strategies over several decades. Much has been accomplished since the discovery
i-Summary The USDA Forest Service, with its expertise in Tools such as prescribed burning, forest health protection, forest management, and pruning, thinning, alternate host control ecosystem and disease research, is uniquely (demonstrated to be effectivein the positioned to implementthis plan, a blueprint to Northeast), and hazard rating projects will ensure white pine survival through management, be used to improve survival of planted restoration, research, and public involvement. pines (Fig. 3).
Integrated Strategy to Protect, Sustain, and Restore White Pines. The survivalof white pines and their ecosystems in North America depends upon a combination of traditional and innovative scientific and management strategies:
=> Genetic Strategies. The best solution known to save white pines ftom white pine blister rust is to enhance numbers of rust resistant white pines (Fig. 2) in Figure 3. Pruned western whitepine plantation. appropriate ecosystems. It is critical to protect existing white pines that have survived the effects of this disease and => Research and Information Needs. Even though much ofthe basic biology ofthe pathogen and its hosts is known, vital research is stillneeded to understand the intricate mechanisms and inheritance of host resistance in order to incorporate them effectively into breeding programs. Figure 2. Rust resistance testing. Long-term perfonnance foster their regeneration in order to of Figure 4. UninfectedRibes. broaden the base of genetic resistance. seedlings The identificationof resistant trees in with improvedresistance, as well as the species such as whitebark pine and epidemiologyof the disease affecting bristlecone pine is also necessary where these seedlings, will be monitored. The we do not yet have well developed role of differentspecies of Ribes (Fig. 4) breeding programs in place. in maintainingand spreading disease also needs further study. => Silvicultural Strategies. Enhance planting of rust resistant white pine => Public Outreach and Partnerships. seedlings in openings created by natural Federal, State, Tribal, and non- disturbances and silviculturalmethods. governmental organizations, and the Creating openings near surviving white public willwork together to protect, pines will enhance planting and restore, and sustain these ecosystems. regeneration opportunities.
Summary - ii The Resource: White Pines and Their a minor to moderate component, to white pine- Ecosystems dominated ecosystemswhere they are the major tree species, to harsh high-elevationsites where ine species of white pines are native white pines are the only conifers that can survive. to U.S. forests: eastern white pine (Fig. 5), western white pine, sugar Historically,white pines thrived in many forests N pine, whitebark pine, limber pine, because of their abilityto regenerate in openings southwestern white pine, Rocky Mountain created by fire, outgrow their competitors, and bristlecone pine, Great Basin bristlecone pine, resist many native insects and pathogens. Today, and foxtail pine. White pines occur naturally in white pine ecosystems are being transformed and impoverishedby the combined effects of white pine blister rust and lack of openings for regeneration (Fig. 6). Without fire or other openings, white pines fare poorly and are replaced by other speciesthat can regenerate beneath the pine canopy. In many cases in western forests, a few conifer species, such as grand fir and Douglas-fir, will become dominant resulting in forests that are less diverse, densely overstocked, especiallyfire-prone, and more susceptibleto insects and disease. Eastern white pine is also favored by fire and other openings, although it is more shade tolerant. However, Figure 5. Eastern whitepine. with limitationson active management, Lake 40 of our 50 states, :tromseashore to timberline States pine forests convert into disease prone, and ttom isolated desert mountain ranges to unthrifty hardwood stands. extensive inland forests. These pines include some of the oldest, most majestic, and most culturally significanttrees in the United States. An ancient bristlecone pine in eastern California is believed to be the oldest livingthing on Earth at over 4,700 years of age.
The great size and superior wood quality of mature eastern white, western white, and sugar pines made them the chief prize of lumbermenas they worked westward across the continent.
White pines play an important role in maintaining watershed health and wildlifehabitat as well as Figure 6. This whitebarkpine ecosystemhas been impacted providing commercialproducts and desirable extensively by blister rust and bark beetles. recreational experiences. White pine ecosystems contain white pines as a significantor dominant part of their coniferous tree cover and play critical roles in forest development and integrity. Examples of white pine ecosystems range ttom mixed-conifer ecosystems where white pines are
1 The Disease: White Pine Blister Rust Ecological Impacts and Its Impacts The effects of blister rust go far beyond the loss hite pine blister rust, a fungus of individualtrees. There is a cascading effect on native to Asia, was introduced to associated plant and animal communities the eastern and western coasts of throughout affected ecosystems. Natural W North Americaaround the turn regeneration and intermediate age classes have of the 20thcentury on infected white pine nursery been rapidly killed by blister rust resulting in stock grown in Europe. In spite of a complicated dramatic changes to normal successional life cycle requiring the presence of gooseberries pathways. In some cases, the impact of blister or currants (Ribes species) as well as pines, the rust combined with lack of regeneration pathogen has spread into 38 states (Fig. 7), opportunities threatens to eliminatethe white causing substantial damage and mortality in pines as functioningcomponents of forest seven of the nine native white pine species. ecosystems. This outcome has significant Infected trees may lose much of their canopy, negative impacts for watershed health, wildlife where cones are produced, years before death habitat, and the abilityof these ecosystemsto occurs. Two white pine species, the long-lived respond to changes brought on by fire, insects, Rocky Mountain and Great Basin bristlecone pathogens and other agents of change. For pines, remain untouched by this disease, but for example,western white pine was once the how long? dominant species on five million acres in the InlandNorthwest.
1920 1925 1953 Current !-~ Forestedlands B.o."".,.",,,,...,.. Forested lands at risk
Figurt: 7. History af whitt: pint: blistt:r rust spread.
2 Today, less than ten percent of that area has a regimes, and reduced wildlifediversity. significantwestern white pine component. Where western white pine have been killed by Bristlecone, foxtail, limber and whitebark pines blister rust or removed to ''pre-empt'' blister rust are among the few conifers adapted to arid and losses, the forest becomes dominated primarily high elevation environments. They are by Douglas-fir, grand fir, western red cedar and sometimesthe only tree species present in the hemlock (Fig. 8), species which are more most austere parts of these ecosystems,or act as susceptible to root diseases, bark beetles, windbreaks for other speciesto grow. They windthrow and drought. The increased mortality contribute to the regulation of snow accumulation
Change in Forest Type 1930-1980 Idaho PanhandleNationalForests
35.0%- 30.0%-
25.0%- [J Historic % -
Figure 8. The acreage of whitepine in one part of theIdaho Panhandle National Forest was once larger than the state of Rhode Island and is now less than l/lO'h of that. Similar changes have occurred throughout the west. caused by these agents, along with changes in and soil stabilization. Many animalsdepend on species and stand structures and subsequent fuels these trees for food and shelter. For example, buildup, has led to a pattern of increased risk of whitebark pine catastrophic fire. Loss of white pine also means seeds are a critical less old growth trees, and less large wood for food source for fish, wildlifehabitat and nutrient cycling. Clark's nutcrackers (Fig. 9), pine Other white pines, such as sugar pine, squirrels, black southwestern white pine and eastern white pine bears and grizzly grow in mixed species stands where they bears, as well as a diversifYforest composition, making these number of small, ecosystems more resilient to changes wrought by seed-eating birds drought, fire, and insects and diseases. The large and mammals. seeds of these species are also important food for wildlife. Mortality of these pines is resulting in Figure 9. Clark s nutcracker is an more homogeneous forests, changes in fire essentialcomponentin whitehal'k pine ecosystems.
3 Economic Impacts
Historically,eastern and western white pines .. were the mainstays of the lumber industry throughout their ranges (Fig. 10). They were prized for their rapid growth and clear, straight- grained wood that commanded premium prices,
Figure 11. Remnant whitebarkpines add beauty to national historic treasuressuch as Crater Lake. Figure 10. Marketable whitepines are in decline. been developed to protect, sustainand restore often more than double that paid for other white pine ecosystems. species in the region. On good sites, western white pines grew to more than 150 feet tall and Integrated Strategy to Protect, Sustain 36 inches in diameter. Mixed western white pine and Restore White Pines stands commonlyproduced 50,000 board feet per acre, while the best mixed fir stands on the same idespread cooperative efforts to sites today are projected to produce only halfthat save white pines were initiated in much. 1909 in both eastern and western W North America. These efforts, Although bristlecone, foxtail, limber and largely focused on eliminatingthe alternate host, whitebark pines are not typicallyused for lumber Ribes (Fig. 12), were not effectivein stopping the or pulp, their presence enhances the rugged beauty of many of our national parks (Fig. 11), ,; ..:i forests, and wilderness areas. Devastation of ...... these species, as seen today in the stands of dead and dyingtrees in Crater Lake, Glacier,and North Cascades National Parks, erodes the scenic grandeur of these treasured landmarksand may affect the tourist economies of adjacent communities.
In light of these impacts, and the key role white pines play in maintaining ecosystem health and resilience, the following integrated strategy has Figure 12. Blister rust infected Ribes.
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J spread of blister rust. Also, the number of Ribes breeding for disease resistance, and application of plants was not shown to affectthe amount of silviculturaltreatments such as thinning and infection in the west, although they were pruning infected branches effectivelycaptured the demonstrated to have a long-lastingeffect on genetic resistance, offering an effectivestrategy infection and survival of trees in Maine. By the for growing white pines in the presence of blister late 1960s, the combined effects of blister rust, rust. This began a pivotal shift in focus from harvesting, fire and bark beetle-caused mortality direct control of the alternate host (reducing devastated the white pine forests in many areas exposure to the rust pathogen) to breeding for rust across North America. In the West, most western resistance (Fig. 13) and using silvicultural white pine management was abandoned. strategies to augmentrestoration. In the past 40 years, genetic breeding programs have produced Fortunately, by the 1960s, USDA Forest Service scientists identifiedrust resistant western white pine, eastern white pine, and sugar pine trees. Rigorous selection of disease resistant trees,
~" I>
Figure 13. 1) rust-resistant sugar pine (inset - blister rust cankers), 2) testing for rust resistance, 3) sugar pine seed orchard, 4) rust-resistant plantation.
5 rust resistant seedlings that have been effective in maintaining a smallbut significantcomponent of these three species in disease-affectedforests.
We realize that blister rust is now a permanent resident of North America, affectingeven the high-elevation and drier forest ecosystems that we once thought would escape infection. Our goal in managing white pine forests is to promote oil' the establishment and growth of white pine trees, stands and populations that will thrive while coexisting with blister rust. We have the expertise and technological tools necessary to reach this goal. This effort will require an integrated approach using genetic, silvicultural and disease management strategies. The intent will be to restore white pines where they have been catastrophically affected by rust infection (e.g., western white pine in the Inland Northwest), to sustain white pines where the rust is present but not yet devastating (e.g., parts of Figure 15. Bristleconepine. the range of southwestern white pine [Fig. 14]), and to plan and prepare for potential spread of the white pine ecosystemscontributes to the main disease where the rust is not yet present (e.g., the goals ofthe "HealthyForest Initiative" and the bristlecone pines (Fig. 15) in California,Nevada, "National Fire Plan" by improvingand restoring Utah, Colorado, and New Mexico). Restoring forest ecosystem conditions. To enhance natural pine resistance, we will focus our efforts on the followingfour general work areas.
Genetic Strategies
The most effectivestrategy availableto combat this disease is to capture and deploy plants with natural genetic resistance to the rust. Although natural resistance is inftequent, we are working with the natural disease resistance present in white pines to identifYresistant trees that can be used as parents of new generations of trees. Genetic conservation and breeding programs have already made considerableprogress towards maintainingsugar pine and western white pine as viable components of ecosystems. The breeding programs continue to discover and develop rust resistant varieties of white pines. In California,a total of 1,329proven rust resistant sugar pine seed trees have been identified,and two seed Figure 14. Infected southwestern whitepine. orchards are established. 6 In the Pacific Northwest, resistance breeding => Maintain broad-based breeding programs programs support 40 seed orchards. The Rocky to prevent the loss of potentially Mountain Region has identifiedmore than 3,100 important sources of genetic variation. rust resistant western white pine trees and planted 96,255 acres with blister rust resistant For white pine species where no disease white pine seedlings. A breeding program is also resistance has yet been discovered, such as high- established for eastern white pine and programs elevation white pine species, land managers can: for whitebark pine and southwestern white pine are in the early stages of development. => Collect seed from disease resistant trees to "bank" genetic diversitywithin species Where blister rust is present, researchers and land and populations. This is a stopgap managers can accelerate the followingactions of measure to ensure that potentially the established breeding programs: valuable white pine genotypes at risk in the wild will be maintaineduntil we can => Locate and protect potentially resistant reduce the threat. Concurrently,test trees, and test seedlingsfrom these trees seedlingsof these selected trees for for resistance. resistance. => Characterize resistance mechanisms and => Implementa conservation strategy (Fig. inheritance of observed resistance. 16) to protect the remainingtrees and => Evaluate test plantations to confirmthe enhance regeneration. durability of resistance. => Breed a new generation of white pines Silvicultural Strategies with a mixture of known resistance mechanisms. Historically,fires created large openings, which => Plant rust resistant seedlingsor seed permitted natural regeneration of white pines. wherever possible. Today,land managers can plant rust resistant => Manage areas around identifiedresistant white pine seedlingsin the openings created by trees and stands to allow openings for large fires. However, we are unlikelyto make regeneration. significantprogress without active management, => Conduct long-term monitoring to assess removal of invading species and/or prescribed the survival of natural regeneration fire. We need to implementsilviculturaltools to compared to planted resistant stock. create the openings necessary for white pine regeneration. The followingactions are necessary to implementgains made in enhancing natural blister rust resistance through the breeding programs:
=> Use rust hazard assessment models to select the best sites for planting and maintaining white pines. => Regenerate stands with harvests that create suitable openings for white pines while saving uninfected and infection- tolerating seed trees to promote natural genetic resistance.
Figure16. Prunedwesternwhitepineplantation.
7 ~ Use prescribed fires to prepare seed beds ~ Conduct periodic surveys to accurately and reduce competing vegetation. map rust occurrence, monitor spread and ~ Plant resistant seedlingsor seed in intensificationof rust incidence, and openings created by natural disturbances identifynew introductions or changes in such as windthrow, fires, root diseases, or rust behavior. bark beetles. ~ Develop hazard rating systemsand other ~ Use pruning and thinning where predictive models to better prescribe the appropriate to remove rust infectionsto best set of managementpractices for extend the life of planted pines. various white pine sites. ~ Plant rust resistant seedlingsin frost ~ Use pruning and thinning where pockets, taking advantage of white pines' appropriate to remove existingrust superior frost resistance. infections and extend the life of existing regeneration. Where blister rust is not currently present or not ~ Use locallygrown nursery stock to avoid yet causing extensive losses, strategies will focus introduction of blister rust into new white on encouraging natural regeneration and, under pine ecosystems. some circumstances, protecting existing stands. These activities must be integrated with other Research and Information Needs land use objectives such as hazard fuel reduction, and improving or maintaining wildlifehabitat Past research and management efforts have (Fig. 17), watershed values and scenic quality. provided us with critical knowledge, technologies Land managers and researchers can: and strategies that are used today to sustain, protect and restore white pine ecosystems. ~ Emphasize the importance of sustaining, However, there are stillmany questions to answer protecting, and restoring white pine in order to improve our abilityto cope with this ecosystems in revisions to National disease. The followinglist describes some of the Forest plans. highest priority research and informationneeds:
~ Identify resistance mechanisms,their heritability,and geographic distribution in all white pine species. ~ Evaluate the linkage of resistance mechanismsto important survival and growth traits, and identifYenvironmental factors affectingthese characteristics. ~Inwst~mevariatIDninRw~ susceptibilityand develop species of Ribes that will resist rust without impacting commercial gooseberry II'J '"' production. (I '" I' ".. { "I'. I " .rJ,., , ,.., ~ Determine impacts of fire, prescribed burns, thinning, and other management Figure 17. Whitebark pine seeds are an important high-caloric part of the grizzly bear diet. essential to their survival through activities on numbers and species of Ribes harsh winters. that may regenerate from seed banks. ~ Examine genetic variation in the rust fungus includingthe potential for new races with differences in virulence,
8 aggressiveness and adaptation to different Conclusion climates. => Develop techniques needed to his plan focuses on protecting, successfullyregenerate species at high sustaining and restoring white pine elevation, naturally or ITomnursery stock ecosystemsthat are either devastated or seeds (Fig. 18). T or threatened by a non-native invasive => Develop seed transfer guidelinesfor all pathogen, Cronartiumribicola, the cause of white pine species. white pine blister rust. It complementsthe implementationof the Healthy Forest Initiative and the National Fire Plan and their associated strategic documents by developing a sensible approach to restoring fire-adaptedresilient ecosystems in the areas where white pine once dominated. It also complementsthe Western Bark Beetle Report by maintainingand restoring high numbers of white pines in ecosystems that have become dominated by other species that are more vulnerableto bark beetles and root pathogens. Increased collaborationand partnerships among land managers and researchers will facilitate the long-term restoration of white pine ecosystems. These
Figure 18. Foxtail seed and pollen cones. restored white pine ecosystems willhave the capacity for self-renewal,recovery and retention of ecological resiliencywhile meeting current and future needs of people for desirable Public Outreach and Partnership experiences, products, and services.
Both internal and external participation and collaboration among Federal, Tribal, State, and private land managers, and non-governmental organizations (Fig. 19) are essential for protection and restoration of the white pines. Forest Service managers and researchers partner in many collaborative efforts to:
=> Provide information on forest conditions and encourage participation in forest management. => Incorporate white pine restoration and sustainabilitygoals into forest plans and field project decisions. => Provide rust resistance testing capabilities Figure 19. Land managers and researchersfrom all agencies for partners. are involved in collaborative efforts to restore whitepines. => Provide financial and technical assistance to small landowners.
9 Team Leaders and Members
Team Leaders: Mary F. Mahalovich, Geneticist, Northern, Rocky Mountain, Southwestern,and Intermountain Regions, Safiya Samman, Geneticist/Forest Health Specialist, Moscow, ill Forest Health Protection (FHP), USDA Forest Service, Joseph O'Brien, Pathologist, Eastern Region, St.Paul, Washington,DC MN John W. Schwandt, Pathologist, Northern Region FHP, John A. Petrick, Center Silviculturist, Dorena Genetic Coeur d' Alene Field Office, Coeur d' Alene, ill Resource Center, Cottage Grove, OR Jill L. Wilson, Coeur d' Alene Field OfficeGroup Leader, Anna W. Schoettle, Research Plant Ecophysiologist, Northern Region FHP,Coeur d' Alene, ill RockyMountain Research Station, Fort Collins, CO. Eric Smith, Biological Statistician, Forest Health Team Members and Contributors: TechnologyEnterprise Team,Fort Collins, CO. Richard A. Sniezko, Center Geneticist, Dorena Genetic V. Clark Baldwin, National Silviculture Research Program Resource Center, Cottage Grove, OR Leader, VegetationManagement and Protection Research Detlev Vogler Research Geneticist/Plant Pathologist, Staff,Washington, DC Institute of Forest Genetics, Pacific SouthwestResearch Station James T. Blodgett, Pathologist, RockyMountain Region FHP,Rapid City Service Center, Rapid City, SD Art Zack, Forest Ecologist, Idaho Panhandle National David A. Conklin, Pathologist, Southwestern Region FHP, Forests, Coeur d' Alene, ill New Mexico Zone Office,Albuquerque, NM Paul Zambino, Research Pathologist, RockyMountain Joan M. Dunlap, Forester/Geneticist, Placerville Nursery, Research Station, Moscow,ill Pacific SW Region, Camino, CA Brian Geils, Research Pathologist, RockyMountain Forest Acknowledgements: and Range Experiment Station, Flagstaff,AZ John T. Kliejunas, Regional Forest Pathologist, Pacific The development of this document would not have been Southwest Region, Vallejo,CA possible without the collaboration and review of numerous individuals within the Forest Service, other land management agencies and universities.
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Weare strivingfor the day whitepines will coexist with blister rust 10