United States Department of Agriculture Forest Insect and Forest Service Disease History of Southwestern Region the Cibola National Forest Forestry and Forest Health Input for the Cibola NF Plan Revision April 2013

Forest Insect and Disease History of the Cibola National Forest

Daniel Ryerson Forest Health, New Mexico Zone Office Southwestern Region USDA Forest Service

April 2013

Cover Photo: U.S. Forest Service photograph of ponderosa mortality in the Datil Mountains, Cibola NF in August 1957.

Content

Introduction ...... 1 Piñon-Juniper Woodlands...... 3 Bark Beetles ...... 3 Defoliating Agents ...... 5 Mistletoes ...... 5 Ponderosa Pine Forests ...... 7 Bark Beetles ...... 7 Defoliating Agents ...... 9 Dwarf Mistletoe ...... 9 Root Disease ...... 10 Mixed Conifer Forests ...... 13 Bark Beetles ...... 13 Defoliating Agents ...... 15 Dwarf Mistletoe ...... 17 Root Disease ...... 17 Broom Rust ...... 17 White Pine Blister Rust ...... 18 Aspen Forests ...... 19 Defoliating Agents ...... 19 Aspen Mortality ...... 19 Spruce-Fir Forests ...... 21 Bark Beetles ...... 21 Defoliating Agents ...... 22 Root Disease ...... 22 Risk Modeling ...... 23 Conclusion ...... 25 Literature Cited ...... 27 Appendix ...... 31

Acknowledgements Andrew Graves and Debra Allen-Reid of the NM Zone staff and Mary Lou Fairweather of the AZ Zone staff provided valuable contributions to this report. Dave Conklin, former pathologist with NM Zone office, contributed to the disease sections of this report.

Forest Insect and Disease History of the Cibola NF i

Introduction

Insects and diseases are important components of forest ecosystems and greatly influence forest structure and species composition over time. While insects and diseases have ecological roles, their impacts often conflict with human objectives and forest management goals. Thus, we refer to their effects as damage, which is true on an individual tree basis or sometimes with respect to resource management objectives; however, it is a term that may not describe the associated ecological effects.

It is not just good forest stewardship to consider the role of insects and disease in our planning; it is also Forest Service policy (FSM 3401.1). Pursuant to the National Forest Management Act of 1976, the Forest and Rangeland Renewable Resources Planning Act of 1974, and the National Forest System Land Management Planning Rule (36 CFR Part 219, Subpart A, RIN0596-AD02 as corrected FR Doc. 2012-18322), consideration of the roles of insects and diseases is required, not only as disturbance agents, but as critical contributors to ecosystem function.

This report summarizes the most common forest insects and diseases on the Cibola National Forest (NF) using information from historical reports, published documents, aerial survey information, and Forest Health staff knowledge. Aerial surveys were started in the Southwestern Region during the 1950s; however, early surveys were often for specific evaluations or projects. The original maps from these early aerial surveys are typically no longer available, but the information was summarized in various reports. Routine annual aerial surveys began in the mid- 1970s and have continued to the present. Summarized annual regional condition reports from 1918 to the present were used extensively for this report with additional information from other reports and survey data and maps when available. National condition reports were used for time periods when the regional reports are not available. When we refer to conditions reports in this document we are referring to these regional and national annual reports. While we present the history for each agent separately since that is often how they are recorded and discussed, insect and disease activity are often closely interconnected. While one agent may be identified as a mortality agent, multiple factors often contributed to the tree’s death. For example, trees most susceptible to attack by bark beetles often are stressed by pre-existing conditions, including dwarf mistletoe infection and root disease. In this report we also consider some possible effects of climate change on insects and diseases.

Forest Insect and Disease History of the Cibola NF 1

Piñon-Juniper Woodlands

Bark Beetles Localized mortality of piñon1 trees caused by the piñon ips bark beetle (Ips confusus) is not uncommon on the Cibola NF. During periods when piñon ips populations are at endemic levels, individual or small groups of stressed, damaged, or diseased trees are attacked. These smaller events create openings and diversity in the woodland structure, providing opportunities for new tree recruitment. High stand density and infection by piñon dwarf mistletoe (Arceuthobium divaricatum) are factors that contribute to increased susceptibility to bark beetle activity (Wilson and Tkacz 1992, Negrón and Wilson 2003). Additionally, slash generated during spring thinning operations can provide breeding material that occasionally results in mortality of residual trees. Trees can also be attacked by bark beetles drawn to the area by the volatile compounds released during chipping and mastication operations in the spring and summer. Extensive outbreaks of piñon ips are primarily triggered and sustained by extended drought. These conditions can also cause outbreaks of the cedar bark beetle (genus Phloeosinus) in juniper, however they are only occasionally observed in stressed trees. Drought-stressed piñon has reduced defenses against bark beetle attack and can provide ideal conditions for bark beetle colonization and reproduction. Widespread changes in the piñon-juniper woodlands can be brought about by extended drought combined with resulting bark beetle activity, such as when the piñon ips caused a significant loss of the piñon compliment in central and northern New Mexico during the early 2000s. Observations of affected areas have indicated varying degrees of piñon survival in the form of mature trees and seedlings.

In addition to historical reports of piñon ips outbreaks, dendrochronological analyses of piñon demography from the Sevilleta NWR (located in the Rio Grande Valley centrally between the districts of the Cibola NF) provide a unique long-term perspective of piñon recruitment and mortality (Swetnam et al. 1998). Based on the dendrochronological research, an extreme drought during the late 1500s is thought to have caused or contributed to substantial piñon mortality in this area, similar to and potentially greater than the better-known 1950s drought period (Swetnam et al. 1998). During the 1920s, our conditions reports record piñon ips activity on Chupadera Mesa, south of the Manzano Mountains (then part of the Manzano National Forest). This outbreak during a dry period was described as “very serious” with mortality levels varying from 10-50% (Pooler 1926); however, this event seems to have been somewhat localized as mortality was not recorded for other areas of the Cibola NF. The estimated mortality dates from the dendrochronological analyses at the nearby Sevilleta NWR correspondingly show a small increase in the number of trees dying during this time period. More widespread and severe piñon mortality was observed throughout NM as a result of the 1950s drought. The1952 insect conditions report observed that on the Cibola NF: “Pinyon pine suffered severe mortality as a result of the recent drought years and large areas of the pinyon type have been killed” (Bongberg 1952).

During the 1950s drought, concern was also expressed that piñon ips were attacking and killing ponderosa pines in surrounding areas, although these attacks were probably from other Ips species that prefer ponderosa as a host. The mortality of piñon on the Sevilleta NWR was greater

1 The use of the ñ in the spelling of “piñon” throughout this document is in keeping with local convention in New Mexico. This spelling is a deviation from the Entomological Society of America’s use of “pinyon” in its list of official insect common names. Whatever spelling convention is used in source documents is carried forward in literature citations.

Forest Insect and Disease History of the Cibola NF 3 Piñon-Juniper Woodlands

in the older piñon age classes, leaving younger trees in many locations. Swetnam and others (1998) observed from their dendrochronological studies that “this mortality episode stands out as a singular event in the five century history of these pinyon-juniper stands.”

The most recent outbreak on the Cibola NF occurred primarily during 2002 – 2004 and was initiated by the drought that began in the late 1990s. This drought was considered to be of similar intensity as the one during the 1950s, but with anomalously high temperatures (Breshears et al. 2005). While the extent of the recent piñon ips outbreak on the Cibola NF was not as severe as in other locations in northern New Mexico, some areas, especially the eastern slopes of the Sandia Mountains and in the Ortiz and San Pedro Mountains incurred substantial mortality of piñon trees. Slightly over 22,000 acres on the Cibola NF were mapped with some piñon mortality during our aerial detection surveys from 2002 – 2005. The majority of the area mapped was on the Mountainair and Sandia Ranger Districts, with more minor activity on Mount Taylor and the Datil Mountains. Additionally, there was piñon mortality on Mount Taylor that occurred prior to our expanded piñon-juniper surveys in 2003 and 2004. This mortality was relatively recent (probably occurring during the early 2000s) and quite evident on La Jara Mesa.

Localized outbreaks of piñon ips will continue to be a part of piñon-juniper woodland ecology and should be expected in dense stands, especially older stands and those under stress from other factors, such as dwarf mistletoe. During drought periods, widespread outbreaks of piñon ips are probable. Figure 1. Extent of piñon mortality The probability of piñon ips activity in the next few mapped on the Sandia and Manzano decades for those areas most severely affected Mountains and surrounding areas during the recent outbreak is reduced due to (1) less during aerial detection surveys from competition among the now more widely spaced 2002 – 2004. remaining trees, (2) previous mortality of the most at-risk trees, including those on very poor sites or those at the edge of the natural range of piñon, and (3) less host type. There is, however, still substantial piñon on the Cibola NF that could be affected in future outbreaks. Betancourt and others (1993) estimate in their history of piñon woodlands there is a high probability of a catastrophic “killing” drought occurring during the potential life span of piñon trees. Based on their observations, piñon populations rarely reach equilibrium and are often affected by disturbance.

Climate change is expected to considerably alter forest insect and disease dynamics (numerous reviews available including Bale et al. 2002, Logan et al. 2003, Ryan et al. 2008). In New

4 Forest Insect and Disease History of the Cibola NF Piñon-Juniper Woodlands

Mexico, the effects of climate change could have significant impacts on our woodland ecosystems. While projections vary, some climate change models for New Mexico include warmer temperatures with a longer frost free period (summary in State of New Mexico 2005). The impact of climate change upon precipitation is less clear; however, an increased potential for more extreme events, such as droughts, is considered a possibility (State of New Mexico 2005). Even in the presence of normal precipitation levels in the Southwest, warmer temperatures alone could lead to tree mortality from moisture deficits caused by an increase in evapotranspiration. (Adams et al. 2009). Periods of drought or even average precipitation levels exacerbated by higher temperatures could contribute to future widespread piñon ips outbreaks.

Defoliating Agents Insects and diseases that cause defoliation of piñon trees typically do not cause substantial or long-term damage. Needle cast diseases appear infrequently and often have temporary impacts, though successive years of infection can result in growth loss and predispose trees to other agents. Direct mortality from needle casts is rare (Cranshaw et al. 2000). Needle cast of piñon is caused by several fungal agents, including Dothistroma. Abnormally high rainfall or humidity levels during the spring and early summer are necessary for the development of a needle cast outbreak. During 2007, a widespread outbreak in New Mexico affected much of the piñon woodlands, including over 27,000 acres on the Cibola NF.

Three defoliating insects occasionally observed on the Cibola NF are the piñon needle scale (Matsucoccus acalyptus), piñon needle miner (Coleotechnites edulicola), and piñon sawflies (Neodiprion edulicolus and Zadiprion rohweri). Piñon needle scale has been observed in the piñon woodlands of the Magdalena and San Mateo Mountains for a number of years. The thin crowns of piñon trees in these areas are often a visible clue to the presence of this insect. These infestations are chronic and reduce the overall vigor of the trees, sometimes contributing to mortality some circumstances. Piñon needle miner activity has occasionally been observed, but the typically short outbreaks only cause temporary defoliation. Piñon sawflies are also observed sporadically, but effects typically are temporary as well. Most recently Z. rohweri has been observed in the piñon-juniper woodlands of the northeast portion of the Sandia Mountains, in and around the vicinity of the City of Albuquerque’s Golden Open Space area. Due to the overall limited impact of these agents, their presence has typically not been of concern and thus we have few records of these agents on the Cibola NF.

Mistletoes Piñon dwarf mistletoe (Arceuthobium divaricatum) occurs in an estimated 10 to 15% of the host type on the Cibola NF. Its behavior and effects are similar to those of ponderosa pine dwarf mistletoe. Its current distribution is presumably similar to that in the 1800s, but the intensity of infestations is believed to be higher due to increased host densities that allow a higher probability of explosively released seeds to land on host tissue. Juniper mistletoe (Phoradendron juniperinum) is common and widespread throughout most of the host type. Heavy infestation of juniper mistletoe increases host mortality, especially during drought. Seeds of Phoradendron spp. are eaten and spread by birds, so are an important winter food source for several bird species.

Forest Insect and Disease History of the Cibola NF 5

Ponderosa Pine Forests

Bark Beetles There are many species of bark beetles that attack ponderosa pines in the Southwest. The primary species on the Cibola NF are: the western pine beetle (Dendroctonus brevicomis), the roundheaded pine beetle (Dendroctonus adjunctus), ips engravers (Ips spp.), and rarely the mountain pine beetle (Dendroctonus ponderosae). The various species of bark beetle often selectively attack specific sizes of trees: Dendroctonus species favoring larger diameter trees while Ips species favor smaller diameter trees or the smaller diameter portions (tops, branches) of larger trees. Both Dendroctonus and Ips species, however, can often be found attacking the same tree. Stand density is an important factor in determining the risk of bark beetle activity and the extent of resulting mortality (see Fettig et al. 2007 for a review of studies). Various studies have found that the risk of a bark beetle outbreak starts when stand basal areas reach the range of 60- 100 ft2/acre and increase with increasing basal area, often reaching a high level of risk at basal areas in the range of 120-150 ft2/acre (Kegley et al. 1997, Negrón 1997). Additionally, thinning slash generated in the spring can provide breeding material and occasionally results in mortality in the residual trees. Standing trees can also be attacked by bark beetles following chipping and mastication treatments completed in the spring and summer. As with the piñon ips, extensive outbreaks of ponderosa pine bark beetles are primarily triggered and sustained by extended drought. Drought-stressed pine trees have much less resistance to bark beetle attacks. Dense, crowded stand conditions can contribute to greater levels of mortality during outbreaks.

Records of bark beetle activity in ponderosa pine on the Cibola NF first occur in condition reports from the 1920s. Bark beetle-caused mortality was reported on the southeast slope of Sandia Mountains during 1922-1927, affecting approximately 2,500 trees. Limited mortality was also observed during this time period near the Tajique Ranger Station. A short-lived, but “serious situation” (Pooler 1925) was described on the Datil, Magdalena, and San Mateo Mountains across a relatively large area with levels of mortality at individual sites ranging from very low amounts up to 75% of the trees. A large wind throw event was thought to have contributed to the outbreak. Bark beetle activity resulting from logging operations was observed during the late 1920s on the Manzano and Zuni Mountains.

The next major period of ponderosa pine mortality recorded was during the 1950s drought. This drought period resulted in tree mortality throughout the southwest. Tree mortality on the Cibola NF was described as “extremely heavy in several portions of the Forest” and “particularly noticeable throughout the pine timber lands in the Manzano Mountains; the Magdalena Mountains; the San Mateo Mountains; the Datil Range and in Figure 2. Extent of “Southwestern Pine Beetle portions of the Zuni Range” Infestation” mapped on the Magdalena RD in 1952. (Bongberg 1952). Surviving maps for the Datil, Crosby, Gallinas and Sawtooth Mountains of the Magdalena RD delineate nearly

Forest Insect and Disease History of the Cibola NF 7 Ponderosa Pine Forests

73,000 acres with “Southwestern Pine Beetle Infestation” on these mountain ranges alone. The general description and that the extent of the area mapped includes lower elevation woodlands would seem to indicate the mortality was of both piñon and ponderosa pine.

Figure 3. U.S. Forest Service photograph taken in 1957 of ponderosa pine mortality on the Magdalena RD. Original caption reads: “Ponderosa pine timber, dead and dying after several years of drouth and attacks of ips bark beetles. This is on the Cibola National Forest, near Datil, New Mexico. By Daniel O. Todd. August 1957.” Photograph No: 482956.

Relatively little activity was recorded during the 1960s. A small outbreak of mountain pine beetle in ponderosa pine was observed on the Mountainair Ranger District in 1963 after beetle populations increased in the white pine component of the mixed conifer forests. Most of the mountain pine beetle attacks on ponderosa were found to be unsuccessful. Increased mortality of ponderosa pines was noted in 1974, particularly scattered mortality resulting from Ips spp. attacks in the Datil Mountains. During the most recent drought period, ponderosa pine forests on the Cibola NF were not as severely affected as the piñon-juniper woodlands. Some ponderosa mortality was mapped during aerial surveys on the east slope of the Manzano Mountains and across scattered areas on Mount Taylor and the Zuni Mountains. From 2002 to 2005, a total of approximately 2,700 acres were mapped on the Cibola NF with some level of ponderosa pine mortality.

Localized activity of bark beetles in single trees and small groups will continue to be a part of the ponderosa pine forest ecology and should be expected in dense stands, especially those under stress from dwarf mistletoe or other agents. The greater abundance of dense, crowded stands due

8 Forest Insect and Disease History of the Cibola NF Ponderosa Pine Forests

to fire exclusion and past management activities has probably increased the potential for bark beetle activity over pre-settlement stands and contributed to higher mortality levels when drought-related outbreaks develop. The most extensive ponderosa mortality from bark beetles recorded on the Cibola NF has occurred primarily during dry periods.

As with the piñon-juniper woodlands, climate changes will affect the bark beetle activity in the ponderosa pine forest type. Dense ponderosa pine forests experiencing increased levels of water stress have a greater potential for widespread bark beetle activity. Shorter drought periods, which previously may not have triggered more extensive bark beetle outbreaks, could under warmer conditions, be sufficient to cause greater mortality (Adams et al. 2009).

Defoliating Agents Defoliating agents of ponderosa pine have historically been of minor significance on the Cibola NF. Needle cast of ponderosa pine caused by Lophodemella cerina was observed throughout the Cibola NF and across other portions of the state during 1988 and 1990. Needle cast diseases appear infrequently and often have temporary impacts, though successive years of infection can result in growth loss and predispose trees to other agents. Direct mortality from needle casts is rare (Cranshaw et al. 2000). Other defoliating agents observed sporadically on the Cibola NF are the pine sawflies (Neodiprion spp. and Zadiprion spp.), which typically only cause minor, isolated defoliation. Occasionally, the defoliation is significant enough to be observed from aerial surveys, such as the 1,200 acres of defoliation in the Zuni Mountains during 1961, an outbreak affecting approximately 700 acres observed from the air and ground in 2009, and defoliation on the Gallinas Mountains during 2011-2012.

Dwarf Mistletoe Southwestern dwarf mistletoe (A. vaginatum spp. cryptopodum) is the most common pathogen of ponderosa pine on the Cibola NF. In the mid-1980s, an estimated 30% of the host type on the Cibola NF had some level of infestation (Maffei et al. 1987), which was lower than the regional average (Maffei and Beatty 1988). Incidence is highest in the Manzano and Gallinas Mountains (Mountainair RD), which in the 1980s survey was measured at 62%. Dwarf mistletoes are persistent, chronic agents, and the overall incidence (acres affected) changes only slightly from year to year. Horizontal spread through forest stands averages one to two feet per year (Hawksworth 1961). Because of spread from ballistic seed and other ecological factors, dwarf mistletoes usually have a patchy distribution within infested stands and across the landscape.

All ages and sizes of trees can become infected. Usually, once a tree becomes infected, the disease slowly intensifies until the tree dies. However, most infected trees can survive for several decades, with gradual decline in growth and vigor. Heavily infected trees are often attacked and killed by bark beetles, especially during dry periods (Kenaley et al 2006 and 2008). Trees infected at a young age become stunted and deformed, limiting growth and development into large trees. While impact from dwarf mistletoe can represent a significant economic loss, dwarf mistletoes, like other native insects and diseases, are natural parts of the ecosystem and tend to increase biodiversity (Hawksworth and Wiens 1996, Geils et al. 2002).

Little direct quantitative information is available on the changes in dwarf mistletoe distribution and abundance since pre-settlement conditions. Heavy logging in late 1800s (railroad logging era) is thought to have reduced mistletoe in some areas of northern New Mexico (Hawksworth 1961).

Forest Insect and Disease History of the Cibola NF 9 Ponderosa Pine Forests

However, this was followed by various modifications of the selection system in other areas, which tends to intensity dwarf mistletoe in residual stands (Hawksworth 1961). The Zuni Mountains and perhaps other portions of the Cibola NF may have experienced these changes.

Since the designation of the National Forests in the early 1900s, management activities, specifically: 1) harvest and thinning and 2) fire suppression, have influenced the abundance and/or distribution of dwarf mistletoes on the landscape (see Conklin and Fairweather 2010). For several decades, harvest and thinning activities throughout the region, including portions of the Cibola NF, selected the removal of infected trees, temporarily reducing infection levels within timber sale and other project areas. However, the vast majority of entries involved some form of selective cutting, which, over the long-term left more infected trees than it removed and tended to favor the spread of dwarf mistletoe. Rarely were attempts made to remove all visibly-infected trees and stand infection levels generally returned to pre-treatment levels in about 20 years (Geils unpublished data). Where some lightly infected trees were retained, average tree size increased due to thinning even though stand infection levels also increased.

While past silvicultural treatments have generally increased stand growth and productivity, they have had little overall effect on the distribution of dwarf mistletoe, since the parasite can only be eradicated with a clearcut and those have rarely been practiced in the Southwest. However, large infected (and uninfected) trees were targeted throughout most of the region. These changes began in the railroad logging era and continued to a greater or lesser extent through the 1980s. Today, older infected stands are relatively uncommon, especially those with large witches’ brooms, which have the greatest ecological value (Conklin and Fairweather 2010).

Maffei and others (1987) report that the incidence of pine dwarf mistletoe on the Cibola NF increased from 13% to 30% of stands/acres infected between the 1950s and 1980s, based on a comparison of roadside surveys that were conducted over the same general area. Such a large increase in 30 years seems highly unlikely, if not biologically impossible but there is general agreement that incidence has increased somewhat over the past century, due to perpetuating uneven-aged conditions that allowed young trees to establish under infected overstory trees. Almost certainly there have been increases in the number of infected trees; this can be assumed simply because of evidence that today’s forests contain many more trees than those in the mid to late 1800s due largely to fire suppression.

Fire is an important natural control of dwarf mistletoe. Following stand replacement fires, trees usually return to burned areas well in advance of the pathogen (Alexander and Hawksworth 1975). Lower intensity fires tend to reduce infection levels via differential tree mortality and scorch pruning lower limbs of surviving trees where dwarf mistletoe infection is typically concentrated (Harrington and Hawksworth 1990, Conklin and Armstrong 2001, Conklin and Geils 2008). Data from six prescribed underburns in northern and central New Mexico, including one on the Cibola NF, indicate that a uniform underburn generating 50% average crown scorch sets dwarf mistletoe back about ten years (Conklin and Geils 2008). In addition to these direct controlling effects, a historic fire regime of frequent low intensity fires would keep forests more open and park-like, limiting tree-to-tree spread of dwarf mistletoe.

Root Disease Root diseases typically occur at low levels in ponderosa pine stands in the Southwest, but can be more severe in localized areas. In general, root diseases reduce tree growth and longevity, often

10 Forest Insect and Disease History of the Cibola NF Ponderosa Pine Forests

resulting in small forest openings. Occasionally, they become more active and damaging following harvest activities, since large stumps serve as persistent food bases for causal fungi; this phenomenon has been observed in a pine stand on Mt. Taylor, where all ages of trees can be affected by root disease.

Armillaria (Armillaria solidipes2), annosus (Heterobasidion irregulare3), and Schweinitzii (Phaeolus schweinitzii) are the most common root diseases of ponderosa pine in New Mexico. Infected ponderosa pines may be more susceptible to bark beetle attack. Root diseases often appear to proliferate on stressed trees, so their significance may increase with climate change.

2 = A. ostoyae

3 = H.annosum

Forest Insect and Disease History of the Cibola NF 11

Mixed Conifer Forests

Bark Beetles The three primary bark beetles in the mixed conifer forests are the Douglas-fir beetle (Dendroctonus psedotsugae), the Douglas-fir pole beetle (Pseudohylesinus nebulosus) in Douglas-fir, and the fir engraver (Scolytus ventralis) in white fir. As with the bark beetles in pines, attacks during endemic population levels are typically on injured or diseased trees. Stand density, composition (percent of stand composed of host species), and host tree diameter are all important factors in determining risk of attack by these bark beetles (Ferrell et al. 1994, Schmitz and Gibson 1996). While outbreaks of both species of bark beetles can occur as a result of drought, other forest disturbances, particularly fires, wind throw events, and for the fir engraver, defoliation, can trigger outbreaks. Since these beetles are host selective, outbreaks can shift the species composition of mixed conifer forests. Although technically classified as a borer, Phaenops drummondi (no common name) feeds and develops in the phloem/cambium interface, much like bark beetles, and can be problematic in weakened Douglas-fir.

Douglas-fir beetle activity was observed on the Cibola NF during the early 1950s, with some “heavy killing” on north facing slopes. In the 1952 conditions report, the Douglas-fir beetle situation was described as: “Activity by this bark beetle is gradually depleting these fir areas but in no instance were conditions noted which would warrant immediate action for direct control.” During the mid 1970s, Douglas-fir mortality was recorded on the Manzano Mountains and to a greater extent on the Datil and San Mateo Mountains. Some activity was also noted more recently during the early 2000 drought on Mount Taylor and the San Mateo Mountains. Because the Douglas-fir beetle has been considered the primary mortality agent in Douglas- fir, the role of many of the other bark beetles and woodborers has probably been underestimated.

Fir engraver outbreaks and overall mortality of white fir are often closely tied to drought periods (Fairweather et al. 2006). Fir engraver activity was first noted in conditions reports during the 1950s drought period. The 1952 conditions report stated:

“During the course of the past four years the fir engraver beetle has developed to epidemic Figure 4. Extent of fir engraver beetle proportions in the La Madera Area of the Sandia activity on the Sandia RD during the Mountains and currently is causing severe loss of the 1950s (black outline) and comparison fir timber” (Bongberg 1952). Reports of fir engraver of fir engraver beetle, western balsam activity during this period are limited to the Sandia bark beetle, and spruce beetle activity Mountains. In 1952 the level of tree mortality in the mapped during 2002-2008 (red shaded areas). La Madera area measured at 2 to 11 trees per acre. Estimates of mortality in 1953 ranged from 20-50

Forest Insect and Disease History of the Cibola NF 13 Mixed Conifer Forests

percent of the stand with levels as high as 80 percent on the west side of the mountain. Maps show the fir engraver activity starting in 1949 and continuing through 1961, encompassing nearly 20,000 acres of the east slope of the Sandia Mountains (figure 3). The outbreak ended in 1963 after 14 years and was estimated to have killed 40 to 60 percent of the trees.

Following the 1950s event until the most recent drought, only minor scattered fir engraver beetle activity was noted, specifically during the late 1970s and early 1980s. During and following the recent drought, mortality of white fir along with corkbark fir on the Sandia Mountains was fairly extensive during 2002-2008, affecting the same overall extent as the 1950s event (figure 3). The extensive area mapped during the 1950s included the higher elevation of the east slope, which contains spruce-fir forests. It is possible that mortality of corkbark fir was included in the 1950s delineation of fir engraver activity. The recent tree mortality on the east slope of the Sandia Mountains included significant corkbark fir and a minor amount of spruce mortality in the higher elevation forest type. During our 2002-2008 aerial surveys, approximately 8,800 acres with true fir and spruce mortality were mapped. Additionally nearly 3,000 acres with white fir mortality were mapped on the Manzano Mountains during this period.

A third bark beetle species, mountain pine beetle, has been recorded in the white pine (limber and southwestern white) component of mixed conifer stands on the Cibola NF. Attacks on white pines were observed in 1959 on the San Mateo Mountains. At the time, this was the most southerly location that this species of bark beetle (classified as the Black Hills beetle during this period) had been found. In the early 1960s “An aggressive infestation of Black Hills beetle” (USDA 1963) was observed on the Manzano Mountains. In 1963 the situation was described: “During the last 5 years this beetle killed most of the limber pine on the Mountainair District, Cibola National Forest, near Albuquerque, N. Mex. With the elimination of limber pine, the beetle is now attacking adjacent ponderosa pine. A ground survey showed more ponderosa attacked in 1963 than in 1962. Thus, it appears that the infestation is gaining momentum” (USDA 1964). Later evaluations found the impact to ponderosa was negligible as most attacks were unsuccessful. Since this event, no additional widespread mountain pine beetle activity has been observed on the Cibola NF.

It is accepted that fire exclusion and past management activities in mixed conifer forests that have contributed to higher stand densities and greater white fir and Douglas-fir composition. These changes have probably increased the potential for bark beetle activity above what would have been expected in pre-settlement conditions and contributed to greater tree mortality when outbreaks do develop. Only two major events of fir engraver beetle activity have been recorded on the Cibola NF, both during and slightly following major drought periods. While specific comparisons of the effects of these outbreaks are not available, the extent and descriptions seem to indicate events of similar severity. Outbreaks of Douglas-fir beetle have not been as prevalent as those of the fir engraver beetle. Mountain pine beetle activity in white pines has only been recorded during one period, but did reduce the abundance of white pines within the affected area on the Manzano Mountains.

While the recent fir engraver activity along with the mortality resulting from the Douglas-fir tussock moth outbreak (see Defoliating Insects section) has substantially reduced the amount of white fir in many stands on the Sandia Mountains, there is the potential for future outbreaks of fir engraver in areas where white fir is still a substantial component of the forests on the Cibola NF. The projections of continued temperature increases and reduced snowpack levels in New Mexico (State of New Mexico 2005) along with competition in dense conditions could result in water

14 Forest Insect and Disease History of the Cibola NF Mixed Conifer Forests

stressed forests that have greater susceptibility to Douglas-fir beetle and fir engraver beetle activity.

Defoliating Agents

Western Spruce Budworm Dendrochronological reconstructions have shown that outbreaks of the western spruce budworm (Choristoneura occidentalis), in the southern Rocky Mountains have long been a part of western forests, occurring repeatedly over at least the past several centuries (Swetnam and Lynch 1993, Ryerson et al. 2003). While western spruce budworm will also feed upon spruce and fir trees in higher elevations, it often causes the greatest defoliation to the preferred hosts: Douglas-fir and white fir. Persistent yearly feeding of western spruce budworm often results in reduced tree growth, top-kill, and can predispose trees to bark beetle attacks (Fellin and Dewey 1986). Direct tree mortality can occur after repeated defoliation, but occurs primarily in the understory, where the trees are heavily fed upon by descending larvae. Over the past few decades, budworm activity has been an ongoing and chronic disturbance in northern New Mexico. While also active on the Cibola NF, budworm defoliation is often less prevalent and damaging than in northern New Mexico. This may be in part to the reduced amount and discontinuous distribution of host type on the Cibola NF. The first mention of western spruce budworm activity on the Cibola NF was in 1941 on the Sandia Mountains. Activity on Mount Taylor was first recorded in 1945. The primary areas affected on the Cibola NF are Mount Taylor and the Manzano and Sandia Mountains. The Magdalena and San Mateo Mountains occasionally have minor amounts of defoliation, but typically not severe or continuing for long durations. Budworm-caused defoliation has been a regular occurrence observed on Mount Taylor. Aerial survey data from 1974 to current shows varying levels of activity throughout this period to the present. Substantial budworm defoliation was observed on the Sandia and Manzano Mountains during the late 1970s and throughout the 1980s, but has less often been mapped from the air from the 1990s. Across the Cibola NF, budworm activity was low during the 2003-2006 time period. This corresponds with long-term patterns observed in dendrochronological reconstructions that outbreaks are more often associated with periods of increased moisture (Swetnam and Lynch 1993, Swetnam and Betancourt 1998, Ryerson et al. 2003).

The long-term reconstructions in northern NM show a trend toward more synchronous and widespread outbreaks (Swetnam and Lynch 1993). These trends suggest that the fire suppression and past logging practices that have led to more contiguous, denser stands, composed primarily of white fir and Douglas-fir, have contributed to more widespread and intense budworm outbreaks. Budworm will continue to be present and part of the ecology of mixed conifer forests. Based on the past activity, budworm will to continue to be a persistent defoliator in the mixed conifer and spruce-fir forests on Mount Taylor and to a lesser degree on the Sandia Mountains. Since outbreaks have been associated with periods of increased moisture (Swetnam and Lynch 1993, Swetnam and Betancourt 1998, Ryerson et al. 2003), the warmer and potentially drier conditions projected in future climate change scenarios could reduce budworm activity and temper severity of future budworm outbreaks.

Forest Insect and Disease History of the Cibola NF 15 Mixed Conifer Forests

Douglas-fir Tussock Moth The Douglas-fir tussock moth (Orygia pseudotsugae) also feeds on Douglas-fir and white fir of mixed conifer forests, but the resulting defoliation is often considerably more severe than that caused by budworm. This insect will feed upon all ages of foliage and can completely defoliate trees, causing substantial tree mortality. Studies in northern Idaho have found that mixed conifer stands on drier areas, such as ridge tops or upper slopes, have heavier defoliation. It is thought that these sites are slightly more stressed because of their drier topographic location and thus more susceptible to tussock moth defoliation (Stoszek and Mika 1978). Stand density is not necessarily an important factor in determining outbreak potential, but thinned stands have been found to have better growth recovery following outbreaks than similar unthinned stands (Wickman 1988).

Relatively short, but intense outbreaks have occurred episodically on the Sandia and Manzano Mountains. Outbreaks of this insect are not frequent, but have caused considerable mortality when they occurred. Outbreaks of varying extent and severity were recorded during 1958-1962, 1967-1968, 1975-1980, and most recently during 2003-2007. A single outbreak on the San Mateo Mountains was observed in 1960.

The extent of the late 1950s outbreak on the Sandia Mountains was described as encompassing “the entire white fir type, about 20,000 acres” (Yasinski 1960). This pattern was also observed during the recent outbreak as much of the susceptible forest on the east slope of the mountain was affected. The discontinuous nature of the mixed conifer forests on the west slopes of these two mountain ranges limits outbreaks to individual canyons. During the recent outbreak, Pino Canyon was most affected with smaller areas of defoliation in Domingo Baca and Del Aqua Canyons. The previous outbreak in the late 1970s occurred in Bear, Domingo Baca, Del Agua, and Trigo (in the Manzano Mountains) Canyons. Evaluation of the impact in Bear Canyon during the late 1970s outbreak, found the level of mortality was 99% of the host trees within the surveyed area (Rogers 1980). Substantial mortality, while not quantified, was also sustained in Pino Canyon and the east slope during the recent outbreak on the Sandia Mountains. In some of the localized areas composed only of host tree species, there was complete tree mortality.

With only a few recorded outbreaks, there does not appear to be a change in the pattern or severity of Douglas-fir tussock moth outbreak frequency. Two of the major outbreaks of Douglas- fir tussock moth on the Sandia Mountains started toward the end of drought periods. The 1970s outbreak was during an overall period of higher precipitation, but followed a couple years of reduced precipitation and snowpack.

Past management activities have probably had some influence upon tussock moth outbreaks. Fire exclusion leading to higher stand densities and greater white fir and Douglas-fir composition in the mixed conifer forests have increased the extent and abundance of susceptible host species and potentially contributed to higher levels of mortality than might have occurred under pre- settlement conditions. In the Southwest, the Douglas-fir tussock moth has a geographic preference, as outbreaks are often limited to the specific locations where outbreaks previously occurred. On the Cibola NF, the Sandia Mountains have had the most extensive and severe outbreaks while the Manzano Mountains have had limited outbreaks, and only single outbreak events have been recorded in the Magdalena and San Mateo Mountains. Future outbreaks of the insect are likely on these mountain ranges where susceptible host type exists.

16 Forest Insect and Disease History of the Cibola NF Mixed Conifer Forests

Dwarf Mistletoe Douglas-fir dwarf mistletoe (Arceuthobium douglasii) is common and widespread on the Cibola NF. Less long-term monitoring has been conducted on this mistletoe in the Southwest, but in 1960, Andrews and Daniels estimated that approximately 50% of the Southwest’s Douglas-fir type was infested. Dwarf mistletoe incidence is very high in the Sandia Mountains, and damage to the host and selective logging, may help explain the domination of white fir (a non-host) in much of the mixed conifer type. However, a large proportion of Douglas-fir occurs in relatively inaccessible, steep terrain, and has experienced fewer silvicultural entries. Similar to ponderosa pine dwarf mistletoe, the overall incidence (acres affected) of Douglas-fir dwarf mistletoe has likely increased somewhat over the past century due to fire suppression. The large witches’ brooms on older infected host trees are beneficial for wildlife, serving as nesting, foraging, and caching sites for birds and small mammals (Hedwall et al. 2006). Hedwall and others (2006) found sixty-seven percent of surveyed Douglas-fir DM witches’ brooms in Arizona and New Mexico were used by red squirrels (Hedwall et al. 2006). Raptors, including Mexican spotted owls, and several passerine birds nest in Douglas-fir dwarf mistletoe brooms (Hedwall 2000).

Apache dwarf mistletoe (A. apachecum) is common on southwestern white pine in portions of the San Mateo and Magdalena Mountains. Its behavior and effects are similar to those of other dwarf mistletoes.

Root Disease Root diseases are generally more common in mixed conifer than in ponderosa pine forests because Douglas-fir, white fir, and other shade tolerant conifers are more susceptible. Root disease impacts likely increased over the past century due to conversion of pine dominant forests to mixed conifer dominant forests across much of the Southwest.

In general, root diseases reduce tree growth and longevity, often resulting in small forest openings. Occasionally, they become more abundant and damaging in the years following harvest activities, since large stumps can serve as persistent food bases for the causal fungi. All age classes of trees can be affected.

Armillaria, annosus (Heterobasidion occidentale4), and Schweinitzii (Phaeolus schweinitzii) are the most common root diseases in New Mexico mixed conifer forests. While each of these has a broad host range, annosus is most often found on white fir, and Armillaria on Douglas fir and spruce. Schweinitzii root and butt rot is most common in old-growth Douglas-fir.

Root diseases often appear to proliferate on stressed trees, so their significance increases following drought, which may be more common with climate change. Infected trees, especially true firs and Douglas-fir, are more susceptible to bark beetle attack than healthy trees.

Broom Rust Fir broom rust (Melampsorella caryophyllacearum) is found throughout the Cibola NF on white fir and corkbark fir. In 1975, its incidence was characterized this way: “Fir broom rust on white fir has been epidemic on portions of the Cibola National Forest for many years” (USDA Forest

4 = H. annosum

Forest Insect and Disease History of the Cibola NF 17 Mixed Conifer Forests

Service 1976). Broom rust infections can cause topkill and branch dieback of the infected trees. This is important in recreation areas or other administrative sites where defective trees can be hazardous to people and property. At times, it has been a concern such as in 1964 on the Mountainair RD: “Considerable mortality has occurred in the Red Canyon Recreation Area, Mountainair District, Cibola National Forest, and elsewhere in localized areas. In addition to tree mortality, cankers weaken the stems which are then easily broken by wind or snow – a serious situation in recreation and other high use areas” (Lucht and Chansler 1964).

Broom rust is especially common in the Sandia and Manzano Mountains; the east side of the Sandia Mountains has one of the greatest concentrations of this disease in the Southwest. Although not considered a “primary mortality agent,” broom rust likely contributed to the stress and subsequent fir mortality experienced in recent years in the Sandia Mountains. From a positive aspect, however, broom rust infections can serve as nesting platforms for wildlife.

White Pine Blister Rust White pine blister rust (WBPR), caused by the fungus Cronartium ribicola, is a recent invasive disease on the Cibola NF and in other parts of the Southwest. WPBR is one of the most damaging tree diseases in North America. It was first detected on the Lincoln NF in 1990 and later spread (via windborne spores) to Gallinas Peak on the Mountainair District. It was found near Mount Sedgwick in the Zuni Mountains in 2007.

The distribution and frequency of blister rust can be expected to increase greatly on the Cibola NF in the coming decades. Eventually the disease will impact white pine populations in many areas, eradicating white pine from the most susceptible areas. Moist drainages and higher elevation stands are the most vulnerable, especially where orange gooseberry (Ribes pinatorum), the preferred alternate host, is present. Even where conditions are especially favorable for blister rust, some trees may be resistant, providing a seed source for natural selection and eventual recovery of the population. On drier, low hazard sites, infection rates and mortality are expected to be relatively low; these sites will serve as important genetic refugia for white pines. Maintaining and promoting genetic diversity among white pines should help insure the long-term survival of these unique trees. We are advocating the retention of white pine during thinning treatments in order to conserve the broadest possible genetic diversity. While the presence of the alternate host, Ribes spp. (gooseberry or currant), is necessary to complete the rust’s life cycle, Ribes spp. removal is not considered a viable control strategy. See Conklin et al. 2009 for more on these topics.

18 Forest Insect and Disease History of the Cibola NF

Aspen Forests

Defoliating Agents The large aspen tortrix (Choristoneura conflictana) and the western tent caterpillar (Malacosoma californicum) are the defoliating agents most often detected by aerial survey on the Cibola NF. Typically these defoliators are not considered detrimental to aspen stands because the trees re- foliate during the same season. However, repeated defoliation over successive years can reduce the growth and vigor of trees and potentially predispose them to other agents.

Tent caterpillar-caused defoliation was first noted on the Cibola NF during 1922-1927 on Mount Taylor and was considered severe in 1926 and 1927, but declined thereafter. No mortality was observed during this period from defoliator activity. Severe defoliation by aspen leaf roller (aka large aspen tortix) was observed throughout central and northern NM in 1943, including on Mount Taylor. The level of defoliator activity recorded in aerial survey data from 1974 to 2008 has fluctuated considerably from nearly nonexistent to greater than 2,000 acres affected during 1986, 1998, and 2007.

Fungal diseases, including black leaf spot (Marssonina populi) and leaf rust (Melampsora spp.), are common on aspen foliage, but since symptoms generally appear later in the summer, they are only occasionally observed during aerial surveys. Damage is primarily aesthetic, often affecting fall color.

Aspen Mortality Aspen abundance is often closely tied to the amount of disturbance on the landscape. Compared with conifers, individual aspen trees are short-lived, in part due the effects of several insects and diseases, but the genetic clone from which it sprouted can be long-lived. Usually found in early- successional stands, aspen are often replaced by conifer species in the absence of disturbances including fire or logging. Various studies and authors have noted that aspen abundance in the Interior West has been declining since the mid-1900s due mostly to fire suppression and the encroachment of conifer species (Kay 1997, Bartos and Campbell 1998). This trend observed throughout the Interior West could be due in part to increases in aspen abundance from the mid 1800s to the early 1900s in response to widespread timber harvesting and extensive fires (Knight 2001). Fires were historically more frequent, but extensive disturbances may have provided for regeneration and increased abundance of aspen, perhaps higher than pre-settlement levels. As landscape disturbances declined beginning in the early 1900s due to fire exclusion and grazing pressure on regeneration increased from both wildlife and domestic animals, aspen abundance in general has declined. Recently, we have been observing aspen mortality throughout NM during our aerial surveys. Aspen on southern aspect slopes is more susceptible to drought, particularly at the lower elevational limit of its range, and entire clones may be affected on such sites. On the Cibola NF, most of this mortality has been on the Mount Taylor RD, which has the most aspen. This mortality appears to be rather abrupt and may be the cumulative effect of years of drought in the early 2000s and 2010s combined with insect-caused defoliation and stem cankers. While this type of event may not be unprecedented in the long-term history of aspen, the limited abundance of this species on the Cibola NF landscape makes this recent mortality of concern.

On Sandia Peak, in areas where there has been no regenerative disturbance in many decades, aspen clone senescence is a mortality factor. The deterioration of these over-mature trees can create hazards in developed recreation sites.

Forest Insect and Disease History of the Cibola NF 19

Spruce-Fir Forests

Bark Beetles The two primary bark beetles in the spruce-fir forests are spruce beetle (Dendroctonus rufipennis) in Engelmann spruce and western balsam bark beetle (Dryocoetes confusus) in corkbark fir. Spruce beetle outbreaks are often started by large disturbances, particularly wind throw events and tend to be associated with larger diameter (>12” DBH) trees. As with bark beetle activity in the other forest types, higher stand densities increase the risk of bark beetle activity in the spruce- fir forests. Western balsam bark beetle attacks have been found to be associated with stands that have a higher fir stand density index. The factors that increase the risk of spruce beetle outbreaks are much the same: density, proportion of spruce in the stand, and size of the trees.

Risk factors for spruce beetle outbreaks (Schmid and Frye 1976)

Risk Physiographic Location Average Diameter Stand Basal Proportion of 2 Category / Site Index of Spruce Above Area (ft / acre) Stand that is 10" DBH spruce(%) High Spruce on well-drained >16 >150 >65 sites in creek bottoms. Medium Spruce on sites with a site 12-16 100-150 50-65 index of 80 to 120 Low Spruce on sites with a site <12 <100 <50 index of 40 to 80

Spruce beetle activity has been observed sporadically on Mount Taylor and to a lesser severity on the Sandia Mountains. Spruce beetle attacks were observed on Mount Taylor from 1963 to 1968. According to a summary report by Lessard in 1976: “Blowdown throughout the Mt. Taylor area provided the impetus for extremely high spruce beetle populations in La Mosca and Water Canyons. Heavy woodpecker predation reportedly caused a reduction in spruce beetle populations in 1964. Populations declined in the area by 1968.” Some spruce beetle activity was observed on Mt. Taylor in the mid to late 1990s. Western balsam bark beetle activity is not as strongly associated with wind throw events. Specific records of this insect on the Cibola NF are uncommon, but corkbark fir mortality from a combination of factors, including western balsam bark beetle and potentially root disease has been occurring recently on the Sandia Mountains and Mount Taylor. Additionally, many of the existing logs and downed corkbark fir shows show evidence of western balsam bark beetle galleries, indicating it has had on ongoing presence. Approximately 1,800 acres with corkbark fir mortality have been mapped on the Sandia Mountains and Mount Taylor between 2006 and 2008.

The infrequent stand replacing fire regime of spruce-fir forests results in stands that prior to a fire are densely stocked with large diameter trees susceptible to spruce beetle and western balsam bark beetle outbreaks (Dahms and Geils 1997, USDA Forest Service 1994). With the limited available history of insect activity in the spruce-fir forests on the Cibola NF, there does not seem to be changes in bark beetle outbreak patterns. Bark beetle outbreaks will continue to be part of the infrequent, but dramatic disturbance pattern of spruce-fir forests.

Forest Insect and Disease History of the Cibola NF 21 Spruce Fir Forests

Defoliating Agents Western spruce budworm also defoliates corkbark fir and spruce, but often to a lesser degree than the preferred white fir and Douglas-fir hosts. The spruce-fir forests on Mount Taylor, however, have been subject to severe budworm defoliation. See the mixed conifer defoliating agent section for more information on western spruce budworm.

Root Disease Root diseases are common on both Engelmann spruce and corkbark fir throughout New Mexico, including the Cibola NF. Infected trees, especially true firs, are often attacked by bark beetles. Other effects of root disease include windthrow. Over time, mortality associated with these (usually) small-scale disturbances create openings and increases forest spatial heterogeneity. Spruce is most often affected by armillaria root disease and tomentosus root/butt rot (Onnia tomentosus5), and corkbark fir can be affected by both amillaria and annosus (H. occidentale) root disease. Root diseases often appear to proliferate on stressed trees, particularly following drought so their significance may increase with climate change.

5 = Inonotus tomentosus

22 Forest Insect and Disease History of the Cibola NF

Risk Modeling

The 2012 National Insect and Disease Risk Map (NIDRM) is a strategic project to assess the potential risk of tree mortality from insects and diseases across the U.S. over a 15 year time period. While it started as a national strategic map to graphically represent risk of tree mortality, better data and models have improved the scale and potential uses of the assessment. The improved resolution (240 m) of the forest parameter data of the new 2012 NIDRM version (Krist et al. in press) allows for more regional and National Forest level analysis and summaries. These insect and disease risk models evaluate the potential loss of basal area based upon current forest conditions. While climate change scenarios are not included as part of the primary risk modeling effort, many of the risk models include climate variables that potentially could be modified to examine how predicted changes in climate could affect insect and disease risk. One scenario was analyzed in the 2012 NIDRM report and it predicted that future climate could further increase risk to the Cibola NF from piñon ips, aspen decline and fir engraver.

On the Cibola National Forest, approximately 148,000 acres are modeled as being “at risk” of losing ≥ 25% of the basal area over the next 15 years. The threshold is set at 25% basal area loss as this is considered to represent “an uncommon, rather extraordinarily high amount of mortality” (Krist et al. in press).

Summary of insect & disease risk for lands within the Cibola National Forest boundary (Krist et al. in press) % Basal Area Hazard Acres Loss Class 0 – 15% Low 1,258,400 16 – 24% Moderate 309,000 25 – 100% High 147,600

Percent of host basal area by agent modeled to be at risk (tree hosts specific to the agent). Risk Agent Percent Mortality Douglas-fir beetle 31.6% Ips spp. 17.2% Aspen / cottonwood decline 14.6% Fir engraver beetle 12.2% Western pine beetle 10.0% White pine blister rust 4.5% Root diseases 2.8% Douglas-fir tussock moth 2.7% Roundheaded pine beetle 2.2% Western spruce budworm 1.6% Dwarf mistletoes 0.2%

Forest Insect and Disease History of the Cibola NF 23 Risk Modeling

Figure 5. Modeled percent basal area at risk from insect and disease activity (gray areas are non-forest).

24 Forest Insect and Disease History of the Cibola NF

Conclusion

Insects and diseases are integral components of forest and woodland ecosystems. Often there are numerous positive impacts of insects and disease on the forest ecosystem including creation of small openings, increasing biodiversity, enhancing nutrient cycling, as food sources for animals, creation of wildlife habitat, and many other ecologically significant benefits. Under severe disease infection levels or episodic outbreaks of insects, however, their effects are more evident, sometimes negative, and cause greater forest change. With the exception of white pine blister rust, the insects and diseases on the Cibola NF often considered pests are native organisms that have long been part of the ecosystem and have evolved with their plant hosts.

Forest and woodland distributions and characteristics are often viewed as static due to the difference in the human life span and the time scale of many ecological changes. Thus evaluation of ecological change or trends in insect and disease patterns depends upon the scale of the time period examined. Long-term paleoecological records provide insight into the presence, changes, and movements of vegetation communities over long time scales. These records reveal that the communities observed today are not static, instead they are dynamically changing with the various influences upon them including climate changes, human impacts, and fire patterns. Human activities have affected and changed forest and woodland ecosystems through direct and indirect actions. In response to these altered environments, the extent and behavior of insects and diseases change. In turn, our view of the effects of insects and disease have also changed.

Beginning in the middle to late 1800s, particularly with the arrival of logging railroads, more widespread forest changes began. Grazing and later fire suppression efforts continued the change in forest and woodland structure. Today’s pine and mixed conifer forests are at greater densities and therefore more susceptible to bark beetle outbreaks, as well as facilitating the spread of dwarf mistletoes. While mistletoe distribution has likely remained similar, harvest activities have probably decreased the abundance of large infected trees in many areas. Although, in some cases, past harvesting activities that left mistletoe infected seed trees, likely increased infestation levels in many regenerating stands. Past harvesting preferences that reduced the pine component of mixed conifer stands have shifted forest composition to greater dominance by shade tolerant species favored by western spruce budworm, Douglas-fir tussock moth, and root disease. Outbreaks of western spruce budworm, in particular, are probably more extensive in the mixed conifer simply because of the greater abundance of host trees.

The relatively short length of most historical insect and disease records and their varying level of detail, however, often prevent quantitative identification of changes or trends in insect and disease activity from pre-settlement conditions to today. With the exception of unique paleoecological records, such as dendrochronological reconstructions, we are primarily restricted to records extending back to the middle or early portion of the 20th century, for our understanding of historical insect and disease activity. Thus bark beetle activity in the open park-like stands of pre- settlement conditions typically cannot be directly compared to activity in a much denser stand today and likely occurred as isolated incidences. Instead, these types of evaluations are made by comparing contemporary insect and disease activity within stands of various conditions, including those similar to pre-settlement.

Overall, the available historical record shows no clear changes in insect or disease outbreak patterns on the Cibola NF. These records, however, are more recent and often concentrate on insect activity, particularly the larger events, such as bark beetle outbreaks. The bark beetle outbreaks on the Cibola NF have often been more climate induced and less influenced by specific stand conditions. While altered conditions may have exacerbated the consequences of these

Forest Insect and Disease History of the Cibola NF 25 Conclusion

events and led to greater mortality, it did not initiate the outbreaks. Thus evaluation of these records reveals more about the role of climate variability in triggering insect activity than changes in insect and disease activity resulting from altered forest and woodland structure.

Invasive insects and diseases pose new threats to forest and woodland ecosystems to which they are not adapted. The lack of adaptation by host species to invasive species can result in unprecedented changes. White pine blister rust is now established on the Cibola NF and expansion of the disease is expected over the next few decades. Blister rust will eventually impact several white pine populations on the Cibola NF. One of the introduced biological control tamarisk leaf beetle species (Diorhabda spp.) has arrived in the region and has begun defoliating stands of the introduced invasive plant tamarisk. The lasting effect of this interaction is yet to be seen.

As has occurred in the past, changes in climate will affect forest and woodland communities. While climate models vary in their predictions, projections for New Mexico include continued increases in temperatures, warmer nighttime temperatures, and a longer frost free period (summarized in State of New Mexico 2005). The impact of climate change upon precipitation is less clear, however reduced snowpack levels and an increased potential for more extreme events, such as droughts, are predicted (State of New Mexico 2005). Changes in climate are expected to considerably alter forest insect dynamics (numerous reviews available including Bale et al. 2002, Logan et al. 2003, Ryan et al. 2008). Even in the presence of normal precipitation levels, warmer temperatures could increase the water stress of vegetation by stimulating higher evapotranspiration levels, leading to mortality (Adams et al. 2009). These stresses will add to the probability of increased bark beetle activity and could exacerbate the effects of root disease. Stress in general predisposes trees to various insects and diseases, but not all agents will respond in a similar way. Mistletoes are dependent upon their hosts for growth, so weaker, stressed stress could actually result in reduced spread and intensification; however, mistletoe effects may become more damaging since mortality among infected trees will likely increase. Some defoliators, such as western spruce budworm, often have outbreaks during periods of increased moisture, so outbreaks might be less severe under a drier, warmer climate.

26 Forest Insect and Disease History of the Cibola NF

Literature Cited

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Cranshaw, W., Leatherman, D., Jacobi, B., and Mannix, L. 2000. Insects and diseases on woody plants in the Central Rockies. Colorado State University Extension, Colorado State University Bulletin no. 506A, 2000. 300p. Dahms, C.W., and Geils, B.W. (Technical editors). 1997. An assessment of forest ecosystem health in the Southwest. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, General Technical Report RM-GTR-295. 97p. Fellin, D.G. and Dewey, J.E. 1986. Western spruce budworm. USDA Forest Service, Forest Insect & Disease Leaflet 53. 10p. Fairweather, M.L., McMillin, J., Rogers, T., Conklin, D., and Fitzgibbon, B. 2006. Field guide to insects and diseases of Arizon and New Mexico. USDA Forest Service, Southwestern Region, Forestry and Forest Health, MB-R3-16-3. 269p. Ferrell, G.T., Otrosina, W.J., and Demars, C.J., Jr. 1994. Predicting susceptibility of white fir during a drought-associated outbreak of the fir engraver, Scolytus centralis, in California. Canadian Journal of Forest Research 24: 301-305. Fettig, C.J., Klepzig, K.D., Billings, R.F., Munson, A.S., Nebeker, T.E., Negron, J.F., and Nowak, J.T. 2007. The effectiveness of vegetation management practices for prevention and control of bark beetle infestations in coniferous forests of the western and southern United States. Forest Ecology and Management 238: 24-53. Geils, B.W., Cibrian-Tovar, J., and Moody, B. 2002. Mistletoes of North American conifers. USDA Forest Service, Rocky Mountain Research Station, General Technical Report RMRS- GTR-98. 123p. Harrington, M.G. and Hawksworth, F.G. 1990. Interactions of fire and dwarf mistletoe on mortality of southwestern ponderosa pine. In: Krammes, J.S., tech. coord. Effects of fire in management of southwestern natural resources: Proceedings of Symposium. USDA Forest Service, General Technical Report RM-191: 234-240. Hawksworth, F.G. 1961. Dwarfmistletoe of ponderosa pine in the Southwest. USDA Forest Service Technical Bulletin No. 1246. 112p. Hawksworth, F.G. and Wiens, D. 1996. Dwarf mistletoes: Biology, pathology, and systematics. USDA Forest Service Agriculture Handbook 709. 410p. Hedwall, S. 2000. Bird and mammal use of dwarf mistletoe witches’ broom in Douglas-fir in the Southwest. MSc Thesis, Northern Arizona University, Flagstaff, AZ. Hedwall, S.J., Chambers, C.L., and Rosenstock, S.S. 2006. Red squirrel use of dwarf mistletoe- induced witches’brooms in Douglas-fir. Journal of Wildlife Management 34: 467-472. Kay, C.E. 1997. Is aspen doomed? Journal of Forestry 95(5):4-11. Kegley, S.J., Livington, R.L., and Gibson, K.E. 1997. Pine engraver, Ips pini (Say), in the western United States. USDA Forest Service, Forest Insect & Disease Leaflet 122. 5p. Kenaley, S.C., Mathiasen, R.L., and Daugherty, C.M. 2006. Selection of dwarf mistletoe-infected ponderosa pines by Ips species (Coleoptera: Scolytidae) in northern Arizona. West N Am Naturalist 66(3): 279-284. Kenaley, S.C., Mathiasen, R.L., and Harner, E.J. 2008. Mortality associated with a bark beetle outbreak in dwarf mistletoe-infested ponderosa pine stands in Arizona. Western Journal of Applied Forestry 23: 113-120.

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Knight, D.H. 2001. Summary: Aspen decline in the West? In: Shepperd, W.D., Binkley, D., Bartos, D.L., Stohlgren, T.J., and Eskew, L.G., compilers. Sustaining aspen in western landscapes: Symposium proceedings, Grand Junction, CO, June 13-15, 2000. USDA Forest Service Proceedings RMRS-P-18: 441-446. Krist, F., Ellenwood, J., Woods, M., McMahan, A., Cowardin, J., Ryerson, D., Sapio, F., and Zweifler, M. (in press). Mapping risk from forest insects and diseases, 2012. Fort Collins, Colorado: U.S. Department of Agriculture, Forest Service, Forest Health Technology Enterprise Team. Lessard, G.D. 1976. The occurrence and control of the spruce beetle in the Southwestern Region. USDA Forest Service, Southwestern Region, Forest Insect and Disease Management, R3-76- 26. 13p. Logan, J.A., Régnière, J., and Powell, J.A. 2003. Assessing the impacts of global warming on forest pest dynamics. Frontiers in Ecology and the Environment 1(3): 130-137. Lucht, D.D. and Chansler, J.F. 1964. Summary of conditions in the Southwestern States. USDA Forest Service, Southwestern Region, Division of Timber Management. Maffei, H.M., Beatty, J.S., and Hessburg, P.F. 1987. Incidence, severity, and growth losses associated with ponderosa pine dwarf mistletoe on the Cibola National Forest, New Mexico. USDA Forest Service, Southwestern Region, Forest Pest Management, R3-87-08. 27p. Maffei, H.M. and Beatty, J.S. 1988. Changes in the incidence of dwarf mistletoe over 30 years in the Southwest. In: Proceedings 36th Western International Forest Disease Work Conference, Park City, Utah. pp. 88-90. Negrón, J.F. 1997. Estimating probabilities of infestation and extent of damage by the roundheaded pine beetle in ponderosa pine in the Sacramento Mountains, New Mexico. Canadian Journal of Forest Research 27: 1936-1945. Negrón, J.F. and Wilson, J.L. 2003. Attributes associated with probability of infestation by the piñon ips, Ips confusus (Coleoptera: Scolytidae) in piñon pine, Pinus edulis. Western North American Naturalist 63(4): 440-451. Pooler, F.C.W. 1925. Correspondence letter from District Forester to Washington, D.C. on insect situation in the southwest during 1925. Pooler, F.C.W. 1926. Correspondence letter from District Forester to Washington, D.C. on insect situation in the southwest during 1926. Rogers, T.J. 1980. A Douglas-fir tussock moth loss assessment evaluation. USDA Forest Service, Southwestern Region, Forestry and Forest Health, R3-80-06. 55p. Ryan, M.G., Archer, S.R., Birdsey, R.A., Dahm, C.N., Heath, L.S., Hicke, J.A., Hollinger, D.Y., Huxman, T.E., Okin, G.S., Oren, R.; Randerson, J.T., Schlesinger, W.H. 2008. Chapter 3 - Land resources: Forest and arid lands. In: Backlund, P., Janetos, A., and Schimel, D. 2008. The effects of climate change on agriculture, land resources, water resources, and biodiversity in the United States. Synthesis and Assessment Product 4.3. Washington, D.C.: U.S. Environmental Protection Agency, Climate Change Science Program: 75-120. Ryerson, D.E., Swetnam, T.W., Lynch, A.M. 2003. A tree-ring reconstruction of western spruce budworm outbreaks in the San Juan Mountains, Colorado, USA. Canadian Journal of Forest Research 33: 1010-1028.

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Schmid, J.M. and Frye, R.H. 1976. Stand ratings for spruce beetles. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Research Note RM-309. 4p. Schmitz, R.F. and Gibson, K.E. 1996. Douglas-fir beetle. USDA Forest Service, Forest Insect & Disease Leaflet 5, R1-96-87. 8p. State of New Mexico, Agency Technical Work Group. 2005. Potential effects of climate change on New Mexico. http://www.nmdrought.state.nm.us/ClimateInfo.html Stoszek, K.J. and Mika, P.G. 1978. Outbreaks, sites, and stands in Brookes, M.H., Stark, R.W., and Campbell, R.W. (editors). The Douglas-fir tussock moth: A synthesis. USDA Forest Service, Technical Bulletin 1585. Washington, D.C. Swetnam, T.W., and Betancourt, J.L. 1998. Mesoscale disturbance and ecological response to decadal climatic variability in the American Southwest. Journal of Climate 11: 3128-3147. Swetnam, T.W., Betancourt, J.L., and Gottfried, G.J. 1998. Role of climate in masting, recruitment, and mortality of pinyon pine. Progress report on Cooperative Agreement No. 28- C4-800 to the Rocky Mountain Forest & Range Experiment Station. 6p. Swetnam, T.W., and Lynch, A.M. 1993. Multi-century, regional-scale patterns of western spruce budworm history. Ecological Monographs 63(4): 399-424. USDA Forest Service. 1963. Forest insect conditions in the United States 1962. USDA Forest Service, State and Private Forestry. 30p. USDA Forest Service. 1964. Forest insect conditions in the United States 1963. USDA Forest Service, Forest Service. 39p. USDA Forest Service. 1976. Insects and disease conditions – 1975. USDA Forest Service, Southwestern Region, Southwestern forest insect and disease bulletin 6(1). 24p. USDA Forest Service. 1994. Insects and disease: indicators of forest health. USDA Forest Service, Southwestern Region, Forest Pest Management Staff, R3-95-02. 29 p. Wickman, B.E. 1988. Tree growth in thinned and unthinned white fir stands 20 years after a Douglas-fir tussock moth outbreak. USDA Forest Service, Pacific Northwest Research Station, PNW-RN-477. 11p. Wilson, J.L. and Tkacz, B.M. 1992. Pinyon ips outbreak in pinyon juniper woodlands in northern Arizona: A case study. Pages 187-190 in Symposium on Ecology and Management of Oak and Associated Woodlands: Perspectives in the Southwestern United States and Northern Mexico, April 27-30, 1992, Sierra Vista, AZ. USDA Forest Service General Technical Report RM-218:187-190. Yasinski, F.M. 1960. Biological evaluation: Douglas-fir tussock moth Cibola, Lincoln & Tonto National Forests. USDA Forest Service. 12p.

30 Forest Insect and Disease History of the Cibola NF

Appendix Acres with insect and disease activity as detected from aerial detection surveys of the Cibola National Forest. Individual bark beetle species are grouped by host / forest type. All land ownerships within the National Forest boundary are included. Values are rounded to ten. * indicates activity detected, but on less than 5 acres. Bark Beetles Defoliators Western Ponderosa Mixed Spruce- Spruce Ponderosa Douglas-fir Piñon Needle Aspen Needle Twig Aspen Year Piñon Ips Pine Conifer Fir Budworm Needleminer Tussock Moth Scale Defoliation Cast Beetles Decline 1974 150 12,590 10 4,180 1975 2,360 180 * 2,260 1976 80 * 4,920 1,290 280 140 1977 170 20 12,760 260 210 510 1978 * 50 5,550 290 120 1979 20 * 3,960 1980 10 30 * 18,730 140 1981 10 40 14,790 530 1982 * 150 19,980 720 1983 180 * 90 13,070 1,060 1984 * 14,220 170 1985 * 9,650 240 1986 30 * 3,800 2,490 1987 * 1,090 1988 20 6,920 1,310 1989 * * 120 22,590 1990 4,930 * 4,500 16,450 1991 80 20 6,960 2,590 1992 240 80 250 600 680 1993 30 50 * 60 1,700 560 3,180 1994 470 360 10 10 6,610 200 70 210 1995 40 * 190 3,990 32,740 840 1,020 3,270 1996 360 60 110 8,110 20 18,990 1,610 290 1997 30 110 270 5,510 24,630 380 630 1998 60 210 180 1,330 180 960 3,270 1999 80 130 210 5,160 1,520 220 2000 20 300 250 2,970 810 2,620 2001 4,370 440 140 5,690 4,820 390 210 2002 4,670 2,350 970 160 1,700 1,050 580 2003 9,930 2,390 1,200 90 200 1,170 2004 8,130 1,180 10,080 220 300 290 1,380 2005 10 5,330 320 250 870 1,440 2006 550 3,960 2,780 1,380 530 1,230 2,850 710 2007 * 1,670 3,820 810 12,500 1,220 32,990 2,880 29,040 30 300 2008 10 2,220 640 520 3,660 12,810 1,060 70 410 2009 30 990 480 820 6,990 7,590 380 4,510 2010 10 380 40 270 3,730 50 240 2011 20 2,150 180 * 3,910 170 200 2012 5,790 12,170 1,190 40 4,180 3,370 110 310 Note damage for 1992 comes for condition reports as data do not currently exist in digital form for the 1992 Cibola NF ADS surveys.

Forest Insect and Disease History of the Cibola NF 31