1

Alaska Aspen Workshop – September 12-14, 2017

Fairbanks – Delta – Tok

Sponsored by the Cook Inlet Chapter, Alaska Society of American Foresters Objectives

Communicate current science about aspen ecology, management, and issues to forest and land managers. Convene people from various disciplines to engage in the lectures and field sessions to share expertise in management and ecology (wildlife, water, fire, utility, harvest).

Address how the landscape-level perspective through mapping and vegetation sampling & monitoring can unite land managers to accomplish common and complementary objectives. We discussed this topic briefly throughout the workshop; more information about inventory and mapping could be integrated into a ‘next’ workshop.

Discuss the current distribution of aspen on the landscape, the potential distribution, and how changes may influence natural resources and biomass values. Consider the effects of climate change, shifts in fire regime, and species migration.

Proposed Outcomes

Find innovative ways to cooperate among land owners, managers, and researchers to accomplish complementary objectives: Enhance wildlife habitat; Plan fuel breaks around homes and communities; Look at opportunities for biomass

Compare various management techniques and results, apply successful treatment tools in new projects.

Consider the changes in climate and fire with respect to aspen’s future on the landscape.

Evaluate pathogens and insects that affect aspen. Consider how these problems will affect current and future management.

September 12, 2017 BLM Northern Field Office, Fairbanks – morning lectures Recent Advances in Aspen Sciences, Monitoring, and Management Paul Rogers, PhD, Director, Western Aspen Alliance Wildland Resources and Ecology Center, Utah State University, Logan, Utah

A brief overview of aspen ecology and management from a western North American perspective included topics covered in the Aspen Field Guide (Rogers 2017): fire ecology, herbivory, climate change, genetics/reproduction, forest classification, monitoring methods, and management techniques. Silvicultural knowledge to maintain or enhance aspen stands should reflect the recognition that the species exists as both a seral and stable community type, the complex range of responses to disturbance are becoming known and should be utilized in management.

A range of scientific and management information is being served on the website of the Western Aspen Alliance.

Managing forests for aspen needs to include management of browsers (herbivory). High elk populations in the western states cause significant damage to regenerating aspen. In Alaska, moose and hare browsing has the potential to stunt a regenerating stand, particularly where treatment has been applied and is the only substantial source of forage in an area.

2

Emerging Diseases of Alaska’s Boreal Forest: Aspen canker and spruce bud blight Lori Winton, PhD., Forest Pathologist, US Forest Service – State & Private Forestry

The most damaging aspen disease in Alaska is presently a localized but aggressive ‘running’ canker that can lead to mortality. The causal fungus is not yet identified, but ground surveys indicate it is widespread across the state. Monitoring across the state is underway to understand incidence as related to site type and stand age and structure.

During our field visits, Lori found running canker on trees of various age classes and size, demonstrating that even young, seemingly vibrant trees less than 30 years old are susceptible to this canker.

Long-term outbreak of the aspen leaf miner in Alaska: consequences for aspen performance in a changing climate. Diane Wagner, PhD., Associate Professor, Institute of Arctic Biology and Biology & Wildlife Department, University of Alaska Fairbanks

The aspen leaf miner (Phyllocnistis populiella) has caused widespread and severe damage to aspen in interior Alaska since the early 2000s. Unusual aspects of the leaf miner's life history, including highly restricted mobility and intense interference competition by larvae, have contributed to the persistence of the outbreak. Leaf mining reduces aspen growth by decreasing photosynthesis and increasing the rate of leaf water loss. Negative impacts of the outbreak will likely worsen under conditions of environmental warming and drought.

Area affected has been monitored from statewide aerial surveys since the early 1990s. Damage peaked in 2007 and declined substantially by 2012, but doubled it from 2015 to 2016 to about 200,000 acres. Leaf miner damage was greater in the Interior than in southcentral Alaska.

Results of manipulative studies are increasing understanding of its feeding ecology and effects on aspen. Parasitoid effects on dynamics of the aspen leaf miner may be influenced by coincident abundance of the willow blotch leaf miner (Micrurapteryx salicifoliella ).

Overview of the Bonanza Creek Long-Term Ecological Research Program Roger Ruess, PhD., Institute of Arctic Biology, University of Alaska Fairbanks

“The BNZ LTER program is designed to understand the interactive effects of changing climate and disturbance regimes on the Alaska boreal forest, and study associated consequences for regional feedbacks to the climate system, and sustainability of subsistence Alaskan communities.”

Aspen Growth Rate Collapse and Mortality from High Temperatures, Drought, and Insect Attack Glenn Juday, PhD, Professor Emeritus of Forest Ecology, University of Alaska Fairbanks

Annual growth of aspen in Alaska is least in warm, dry summers, and greatest in cool, moist summers - the same climate controls as white spruce. From 1850 to 1990, aspen was subject to periodic outbreaks of defoliating insects, especially large aspen tortrix (Choristoneura conflictana), lasting 1 to 5 years. Climate conditions since the mid-1970s have been uniquely unfavorable for aspen growth, and in 1998-2012 severe, sustained defoliation by aspen leaf miner was associated with a growth collapse and mortality. Starting in the 1970s, temperature control of aspen growth has shifted to late winter/early spring, and wet summers since 2014 have improved growing conditions modestly.

Lunch talk: Management of Aspen Communities for Wildlife Habitat Benefits Tom Paragi, Wildlife Biologist, Alaska Department of Fish & Game

Aspen trees provide forage (male buds for grouse, bark and dormant winter twigs for moose and hares) and cover (stem height and density) used by birds and mammals as habitat during post-disturbance succession. However, the range of vascular and non-vascular plants and associated

3

invertebrate and vertebrate species that compose aspen communities are the food web that determines biological diversity.

ADF&G began its habitat program in the 1990s to maintain patches of early and mid-seral aspen in the matrix of mature aspen or aspen-mixed forest near the road system that provides public access. Management actions were initially focused on the feasibility of disturbing mature stands in the absence of a fiber market. Large wildland fires beginning in 2004, including near the road system, have created large seral cohorts that will mature into large patches of similar structure and age rather than the scale and configuration of patch disturbance often optimal to wildlife that provide hunting and viewing opportunity. Management actions have shifted to creating patches of early seral aspen-willow communities in large post-fire stands and working with fire managers to create fuel breaks that reduce risk of wildland fire spread while enhancing wildlife habitat and berry picking opportunity. Field trips near Fairbanks, Delta, and Tok during the workshop will provide a glimpse of 1-20 year response lags to different management treatments.

Recent change in Alaska climate and ongoing changes in human desires for forest products and intangible values create a challenge for scientists and managers to translate learning from field observations into factually-informed planning and policy implementation. The complexity of site conditions, disturbance history, and response trajectories provide a wealth of questions for scientific monitoring.

Afternoon Field Trip to Nenana Ridge; discussion lead by Tom Paragi Nenana Ridge is about 30 miles west of Fairbanks in the Tanana Valley State Forest and is part of the broad physiographic zone of the Yukon-Tanana uplands. In the absence of a fiber market, ADF&G and the Alaska Division of Forestry conducted aspen regeneration treatments (ca. 5-30 ac) with spring fire and dormant season felling during 1995-2006, funded in part by the Ruffed Grouse Society (RGS). Ring counts indicated the stands followed a large disturbance about 1920 (Glenn noted that dendrochronology records indicate major fire seasons a couple years either side of that year). Current successional trajectories on this southeast facing ridge illustrate the effects of initial site condition and treatment.

Figure 1. Nenana Ridge treatment sites

4

Treatments were implemented as moose density in the surrounding region (Game Management Units 20A and 20B) was nearing a peak of about 3/mi

2 by 2003, followed by about 30% reduction through

liberalized harvest during 2003-07. During peak density, substantial moose browsing occurred in the regenerating stands, especially as migrants passed over Nenana Ridge in fall. Hare density at nearby Bonanza Creek LTER peaked in 1999, bottomed out in 2002, and peaked again in 2009. Taller aspen stems are reaching a free-to-grow height of 3 m, but effects of moose browsing on aspen growth and architecture during recruitment remains visible today. Height growth was robust in the last two growing seasons for aspen and white spruce, possibly because of relatively wet summers.

Figure 2. Spruce was not felled in aspen treatments, so some advanced regeneration is now co-dominant in the canopy.

Figure 3. Steeper burn

sites where fire behavior

caused nearly complete

aspen and spruce

mortality are now

dominated by aspen with

some willow and poplar

but white spruce

seedlings are well

established (presumably

from seed). Steeper

felling sites have taller,

more robust aspens,

likely because of better

drainage and warmer

soils.

5

Lori and Roger observed that aspen running canker is most common in younger trees in mature stands where larger trees are also affected but to a lesser degree; however, the disease is much less prevalent in younger stands recovering from disturbance They noted analysis of their monitoring plots across Alaska is intended to discern whether infection incidence is related site type (topography, soils, etc.), stand structure, and/or stand composition. This summer Lori and Roger began inoculation trials on trees in young stands, including in this area. Tom observed that crown mortality in adjacent mature aspen still remains relatively low, but many of the dead/down mature trees appear to have died from the canker.

On flatter sections of felling sites, aspen growth appears dense but stunted and unlikely to achieve the stature of surrounding mature aspen of the same age, in contrast to steeper felling sites. Effect of moose browsing soon after disturbance is evident on many stems, possibly greater near edges where moose access was less hindered by dense felling debris. Permanent plots established after 2 growing seasons on 6 burn and 6 felling sites will allow evaluation of differences in establishment when those stands are revisited in the near future.

September 13, 2017 Drive to Delta for field visits Delta Junction Bison Range – field sites treated for wildlife habitat ADF&G Discussion Leads: Tom Paragi, Wildlife Biologist; Clint Cooper, Manager DJBR; Sue Rodman, Program Coordinator; Cameron Carroll, Small Game Biologist Mile 1408 Alaska Highway, about 12 miles southeast of Delta Junction, is in the glacial outwash plain of the Alaska Range. In 2008 ADF&G contracted dozer crushing of dormant mid-seral aspen in the 1987 Granite Creek burn to reintroduce stand age and size diversity for habitat benefits in a highly accessible area near a flood control project and the western edge of the Delta Junction Bison Range.

Crushing was done as moose density in the surrounding area (5.4/mi2, southwest GMU 20D) was

reduced 41% through liberal antlerless harvest in 2007-08. Hare abundance followed a similar temporal pattern as in Fairbanks, increasing as moose density decreased.

Compared with debris from mature trees, the debris from stems in the 1987 burn was smaller and less hindering to wildlife and humans. Aspen and willow regeneration has received browsing, but growth forms are not as heavily influenced as aspen regeneration at Nenana Ridge.

Figure 4. Delta Junction

Bison Range, Mile 1408

Treatment Sites and

Panoramic Field Complex

6

The Panoramic Field Complex of the Delta Junction Bison Range is an ADF&G managed area designed to provide forage for introduced plains bison. The intent is to provide attractive forage to delay bison movement onto private agricultural fields north of the Alaska Highway until after barley and other grains are harvested in fall. We viewed the western edge of this field where the range manager Clint Cooper explained how the fields are mowed, tilled, or planted with forage crops on a seasonal and annual schedule. Aspen windrows provide for grouse habitat while also serving as snow fences for downwind snow accumulation that supplies moisture to the fields as they dry out in April winds. Prescribed burning in

some of these panels in April 2017 was intended to disturb brush encroachment and enhance grass and forb biomass presumed attractive to bison. Aspen, willow, and perennial grasses regenerated after the April burn. Figure 5. Northwest corner of the Panoramic Field Complex. Aspen wind rows on the left of the photo extend the lengths of some field areas. The hardwood regeneration was stimulated by the spring burn 5 months prior to the photo.

Dan Rees noted that annual spring burning of military ranges to reduce brush encroachment has failed to kill aspen, although Roger Ruess noted that regular mowing during the growing season, if frequent enough, would likely kill aspen eventually. However, it is uncertain whether mowing is logistically possibly on a frequency to accomplish a shift to a grassland state. Dan noted that a rotation of burning, mowing, and herbicide use had been successful in reducing aspen and willow and promoting grasses and forbs on military drop (parachute) zones. However, even with herbicide it is not a complete conversion. A combination of treatments may allow ADF&G to stretch out the time between treatments, reducing cost and effort required for brush control on an annual basis. Discussions centered on designing experimentation to see whether fire, mechanical disturbance, or woody broadleaf herbicide (individually or in combination) could hinder aspen and willow regeneration to a level acceptable for grass and forb enhancement while feasible given the budget and labor available to manage the bison range. The fires were applied to a range of field panels with different disturbance histories, which further complicates inference but is tractable with careful study design. Roger commented that it would be interesting to know whether intensive management for a few years would push the system to a condition that would require less management over the long term.

Mile 1402 Alaska Highway is the entry to 7 miles of forest road created in 1994 with Ruffed Grouse Society funding. A site was logged of aspen in 1997, and additional sites (ca. 10-45 ac) were shear bladed and windrowed in 2000 and 2002.

7

Figure 6. Delta Junction Bison Range, Mile 1402 Treatment sites

Aspen size and density is greater in panels cleared of debris than on windrowed panels, and aspen vigor in sheared sites is greater adjacent to robust mature trees than adjacent to dying or dead aspen as black spruce increases in dominance. Observations during a walk along the treatment site edge suggested that soil type and organic layer depth (evident in associated vegetation, e.g., presence of Ledum) may be a driving factor in the variable aspen response. Tom noted that aspen crown mortality in mature stands was about 15% when treatments were implemented but appears greater now, and others noted aspen running canker was prevalent. Regeneration is generally less robust in Delta (next image) than at Nenana Ridge.

8

Figure 7. Aspen regeneration from a 2002 shearblade treatment adjacent to a mature stand of aspen in decline.

Height growth was robust in the last two growing seasons for aspen and black spruce, possibly explained by relative wet summers.

Permanent plots established after 2 growing seasons on all 6 shear blading sites and in the 1997 feller buncher site (potentially the highest site index based on felled tree size) where a small moose exclosure was constructed in 2000 will allow evaluation of differences in establishment when those stands are revisited in the near future.

Dinner talk at Tanacross Tribal Hall: Grouse ecology and habitat management Cameron Carroll, Small Game Biologist, ADF&G The ecology of ruffed grouse (a solitary species except for broods) and sharp-tailed grouse (a social species for breeding and wintering) is tied closely to their respective habitat needs. Conducting treatments to provide for a mosaic of variable aged aspen stands incorporates guidelines for patch size, edge effect, proximity of habitat needs to brood sites, and treatment methods. The roller chopping area in the 1990 Tok burn occurred in 2015-17 near a public access easement west of the Tok River.

9

Figure 8. Roller chopped units 2015-2016 (3 treatment seasons) within the perimeter of the 1990 Tok

River Fire.

Peter Talus noted the roller chopping area is a diverse post-fire vegetation community where small differences in topography and proximity to small drainages influence presence of woody species. The value of enhancing patches of aspen has to be assessed in the context of how these patches influence habitat values across the landscape with respect to its spatial diversity. Questions on how to demonstrate numeric response by intended wildlife (grouse and moose) or increased use or harvest success by people led to discussion about the challenges of scale in study design and importance of pre-treatment data. Single roads for machinery access allow focused sampling of biological or harvest data through hunter check stations to gauge effort and success (verbal or by questionnaire), wing barrels for grouse age-sex inference, and road traffic cables for general use of area. Tom noted that grouse habitat enhancement in this patchwork scale should benefit local chick production but that grouse abundance varies regionally, often coincident or with a brief lag to hare abundance because of shared predators. The ability to count drumming male ruffed grouse for the region on standard routes (occupancy index for breeders) is hindered by limited access to undeveloped grouse habitat, which complicates comparison with the small treated area. Moose monitoring has similar challenges because abundance or productivity (e.g., twinning rate) is assessed by aerial survey at the population level over hundreds or thousands of square miles. Winter fecal pellets are a rough index to habitat use for comparison of pre-post frequency in treated and untreated areas, or fecal DNA could be used to estimate moose abundance in treated and non-treated areas during the hunting season, but harvest by hunters is reported at large (drainage) scale.

10

September 14, 2017 Tok Forestry Office briefing and field visits Discussion leads: Derek Nellis, Area Forester and Peter Talus, Fire Management Officer, Division of Forestry; Jeff Wells, Assistant Area Biologist and Cameron Carroll, Small Game Biologist, ADF&G The Tok school boiler began operation in 2007, and use of this novel technology in Alaska has required adaptation and learning. Aspen could be a fuel for the Tok school boiler, which presently burns primarily sawdust from a local mill and spruce chips from hazardous fuel reductions near town. Regenerating aspen could provide wildlife cover and forage in a shaded fuel break or clearcut where dense young trees retain moisture on the ground to mitigate spread of wildland fire. Managing multiple aged stands serves the habitat needs of grouse and moose, along with other birds and small mammals. Peter noted that frequent changes occurred in operation of the boiler system as it has been and continues to be adapted (most recently for a low-pressure steam generator for electricity), so fuel requirements for a “typical” heating season are unknown. Limited data on aspen growth and yield for this area further complicates a calculation of annual allowable cut and whether the heat yield from aspen alone is sufficient for the school needs of combined heat and electricity production. The 7-Mile Tok Cutoff Highway. This fuel break was created during a wildland fire event in 2014. The treatment was to cut all spruce but leave mature aspen on the periphery, which produced little clonal regeneration. Logging slash remains while herbs and shrubs are propagating. Longevity of this fuel break may perpetuate for some time as the regeneration of spruce is also sparse, but it may prove beneficial for increased berry production. Aspen recruitment from seed is hampered by lack of an exposed seedbed; discussions centered on whether that could be achieved through other mechanical means that expose mineral soil.

Figure 9. 7-Mile Tok Cutoff Highway fuel break. MP 122.5 Tok Cut-Off Highway - Field visit to 1990 Tok River Fire where ADF&G partnered with DOF to roller chop units for moose and grouse habitat enhancement. The aspen regeneration across this area is out of reach for moose to browse on, and it is all of the same age class. Moose need accessible forage that is less than 2 inches in diameter at 3 meters in height. Grouse need variable aged stands to address their needs for food and cover during all life stages. Aspen has been roller chopped in 5-20 acre units since 2015 (next image, 63.282647 -142.955978). Nearby willow sites near the Tok River floodplain were crushed in the 1980s and 1990s. Projects have been supported by the Ruffed Grouse Society, and then later by a federal aid award through Pittman Robertson funding.

11

Figure 10. Two years of aspen regeneration after being roller chopped. Aspen in the background is 19-23 feet tall at 26 years after the fire. Aspen in the foreground is 18-36 inches tall.

Aspen regeneration appears robust in the roller chopped sites with burned debris largely broken into segments and young aspen debris crushed close to the ground to aid decomposition (next 2 images)

Figure 11. Roller chop unit is towed behind a bulldozer. The cylinder is filled with glycol to weight down the cutting edges for improved ‘chopping’ of tree stems during frozen conditions. Figure 12. Debris remaining after being roller chopped is on the ground, decomposes quickly, and is manageable to walk through. Compared to the mature stands in the background, they have residual jack-strawed spruce still 1-4 feet off the ground from the 1990 wildfire.

Peter noted that commencing work as soon as the ground is frozen is advisable to aid breaking debris at the chopper bars but before snow creates a packing hindrance on the roller drum. He

12

suggested that if top killing aspen is the goal, roller chopping in the summer might work (but see caution below where spruce is regenerating). The small roller choppers in Tok can handle stems of up to 4 inches diameter, whereas the larger one can handle stems up to 5 inches. The dozer pulling the roller chopper will push over the trees with its blade, so tree height isn’t a factor.

Unlike in Fairbanks and Delta, tree height growth on nearby stems 10-20 years old was not outwardly greater in the last two growing seasons; comparison of rainfall records among the areas might be insightful.

Field visit to Red Fox Road on northern edge of Tok for woody fuel response in shaded fuel

breaks and at roller chopping sites. Shaded breaks or severe thinning were created north of the road

to interrupt coniferous crown cover for defensible space after a 2002 fire came to the edge of the

subdivision and caused evacuation. Where the fire crossed south of the road, the site immediately north

was roller chopped in summer 2015 to knock down standing dead spruce and further stimulate aspen

regeneration.

Figure 13. Red Fox Road treatment in 2002 resulted in slow vegetative response, but has filled in with aspen and spruce (2017). Figure 14. Red Fox Road site in

the foreground was roller chopped

in 2015, after its 2002 treatment.

The seemingly dense spruce

seedlings may be from seed and

disturbance from recent summer

scarification. In the background,

the site was not treated after it

burned in 2002.

Cold temperatures, frozen ground, and adequate conifer height and diameter may be needed for

crushing, roller chopping, or shear blading to effectively reduce conifer regeneration while minimizing

scarification.