Aspen (Populus tremuloides) in Utah landscapes is prized not only for its aesthetic value but also because it provides habitat for game and non-game wildlife species, shelter for livestock, and can serve as a fuelbreak (DeByle & Winokur 1985; Fechner & Barrows 1976). Aspen is also associated with disproportionately high levels of bird and plant diversity. The decline of aspen in Utah forests due to drought, conifer encroachment, and/or ungulate browsing is an increasing concern (Worrall et al. 2013), and aspen decline has become a dramatic feature of many Utah landscapes in recent years. The traditional silvicultural approach for regenerating aspen is through coppicing (clearcutting) of existing mature aspen stands, which can stimulate vigorous suckering when protected from browsing. However, coppicing can only be used where aspen stands already exist, and it does not increase genetic diversity, which is needed for adaptation to changing climates. For these reasons, we have been investigating seedling-based approaches for aspen restoration in Utah, following approaches commonly used in Alberta, Canada in mined-land reclamation (Pinno et al. 2012). Aspen trees can produce copious amounts of seed, and because they are dioecious, seed from a single tree will represent many paternal trees and therefore a high level of genetic diversity. Our work over the past 4 years has demonstrated that aspen seed production occurs every year in Utah landscapes, and that seed lots have germination rates of over 95%. We have a collection of aspen seeds from trees in northern and central Utah from 2014-2017, and have successfully grown over 6,000 containerized seedlings in a nursery setting in the past from these seed stocks. In a previous study on Cedar Mountain we had limited success with outplanting aspen, due primarily to drought and rodent herbivory (Howe 2018). However, our work indicated that nursery production of seedlings is not a problem, and that improved site selection and site preparation could dramatically increase the success rate in the first critical years of establishment. Aspen seedlings do occur naturally in western state landscapes, particularly in the first few years after fires (Long & Mock 2012; Fairweather et al. 2014), when herbivory and vegetative competition for light and water are reduced. Thus, aspen seedling-based restoration may have the highest success rate following large moderate-to-severe fires. Once aspen seedlings are established, they can expand into large persistent clones, in contrast to other non-suckering forest trees, where a single seedling produces a single tree. We anticipate that nursery-grown aspen seedlings could become an important component of post-fire restoration, particularly as planting protocols are optimized. Such planting efforts could be important in: 1) increasing the aspen component of Utah's forests, by establishing aspen where it does not currently exist, 2) increasing the resilience of Utah's forests, by dramatically increasing the number and genetic variation of clones on the landscape, and 3) increasing successful aspen establishment in defensible spaces or in strategic fuelbreak areas. The Brian Head Fire, which burned over 70,000 acres in late June 2017, provides exactly this window of opportunity. There are aspen stands remaining at the edges of the Brian Head fire footprint (a dramatic illustration of the fuelbreak capacity of aspen stands), and vigorous suckering from these stands was already evident in the fall of 2017.

The overall goal of the project is to plant genetically diverse aspen seedlings in the Brian Head fire footprint, in locations where aspen does not currently exist. This objective directly relates to UWRI's priority area "Watershed health and biological diversity." These aspen seedlings will increase biological diversity at the genetic level up to the community level, since aspen support remarkably diverse biological communities. Specific objectives include: 1. Demonstrate the operational feasibility of using nursery-grown aspen to establish stands in new areas in a post-fire environment. Locating one plot in the Wildland-Urban Interface (WUI) may encourage neighboring landowners to plant additional aspen on their own property. 2. Assess what planting methods work best, based on previous work. The plots will incorporate several strategies to increase survival during the first 2 years, when mortality is expected to be highest. The outcome of our project will be an improved understanding of the planting protocols needed for nursery-grown aspen seedlings in large post-fire landscapes and/or defensible spaces around structures. The improvement of methods to establish aspen seedlings in wildland fire footprints is a clear benefit to Utahns, both because of the ecological benefits of aspen forests and the potential for aspen stands to serve as fuelbreaks. 3. Contribute to forest restoration protocols that improve habitat, increase biological diversity, and increase watershed health for generations to come. The successful establishment of seedlings through improved planting protocols has the potential to dramatically increase genetic diversity, and hence adaptive potential, in Utah's forests.

Aspen forests in Utah are threatened by increasing drought frequency and intensity, a legacy of fire suppression and conifer encroachment, and intense ungulate browsing pressure. Current aspen regeneration methods are limited to clearcutting existing stands, and seedling-based protocols have not yet been developed. The Brian Head fire presents an excellent opportunity to develop aspen seedling strategies for restoring aspen in large post-fire environments. For the next 2-3 years, the burned areas left by this fire will have reduced herbivory, reduced vegetation competition, and bare mineral soils, which are ideal conditions for aspen seedlings. Once conifers and other vegetation are re-established, this opportunity will close.

Utah Black Bear Management Plan V. 2.0 (2011-2023): Objective 1 of the plan is "Seek to prevent the loss of occupied and suitable unoccupied bear habitat and to improve existing bear habitat through 2023." Aspen stands provide critical habitat for black bears. The management plan states that "aspen stands are probably the most important forest community [for black bears] in Utah, providing both cover and food." This project will directly address improved bear habitat by planting and evaluating strategies for establishing aspen habitat. Utah Mule Deer Statewide Management Plan: Habitat Objective 2 is "Improve the quality and quantity of vegetation for mule deer on a minimum of 500,000 acres of crucial range by 2019." Strategies d, e, f and g under this objective address aspen. Strategy f specifically states "Seek opportunities through the Watershed Restoration Initiative to improve aspen communities that provide crucial summer habitat for mule deer." This project will directly address the objectives and strategies related to aspen in the mule deer management plan. Utah's Wildlife Action Plan (WAP): The WAP identifies Aspen-Conifer as a key habitat that may be addressed through project planning in the Panguitch Municipal Watershed NEPA project. A potential conservation action is: 2.3.14: Conduct upland vegetation treatments to restore characteristic upland vegetation, and reduce uncharacteristic fuel types and loadings. This project will design and test treatments to restore characteristic vegetation. Dixie National Forest Land Resource Management Plan (as amended): Goal 15 is "Maintain or enhance the terrestrial habitat for all wildlife species presently on the Forest" (page IV-5). A general direction is to "Maintain structural diversity of vegetation on management areas that are dominated by forested ecosystems. Manage aspen for retention wherever it occurs." Utah Elk Statewide Management Plan: The plan states "although elk inhabit most habitat types in Utah, they prefer to spend their summers at high elevations in aspen conifer forests." It also states "Elk in Utah are more closely tied to aspen than any other habitat type." Habitat Management Goal B is "Conserve and improve elk habitat throughout the state." As a primary habitat for elk, this project addressing aspen re-establishment directly relates to improving habitat for elk.

Except in the most severe fires, mature aspen stands can function as fuelbreaks. The rate of spread, heat energy released, and difficulty of fire containment are all lower in aspen stands compared to conifer stands. Managers often report that crown fires "drop to the ground" in aspen stands and can provide a valuable opportunity for fire control. Values that can be protected with appropriately sized and located fuelbreaks include human communities; permanent infrastructure such as power lines and roads; municipal watersheds; campgrounds, and critical wildlife habitat. The establishment of aspen in areas where it has been lost or does not currently exist will require planting. However, nursery and planting protocols for aspen seedlings in western landscapes are just now being developed (Long & Mock 2012). This project will be a significant step toward developing protocols for large-scale seedling-based aspen restoration in fire-prone landscapes. The project could also help promote planting of aspen seedlings in defensible spaces around homes and structures.

Plants of any kind are regarded as beneficial in post-fire environments, because their roots stabilize the soil and help to prevent erosion, decreased water quality, and increased water runoff to downstream systems. Aspen may be particularly beneficial to watersheds because mature stands have been shown to increase water yield relative to conifers (LaMalfa & Ryel 2008). Additionally, because of its highly networked root system, aspen may be especially effective for erosion prevention. The purpose of this project is to improve our understanding of how large-scale seedling-based restoration could become operationally feasible, which has watershed benefits in addition to biodiversity and habitat benefits.

We expect that NEPA clearance will be required for any plots on USFS-owned land, but not for private land. We will work with USFS District personnel in early summer to obtain any necessary clearances for installation of our fenced plots

The project will be designed to quantitatively assess the benefits of the following variables in planting protocols: site selection, mulching, the use of coarse woody debris, and exclosures to minimize ungulate herbivory. Task 1: Seedling production. A target of 4280 aspen seedlings will be produced in the Harrington Forestry Research Center in Mora, New Mexico. This facility has successfully produced aspen seedlings in recent years, and has experience using aspen seedlings for reclamation of mined lands. Seedlings will be grown in D16 pots and will be induced to set bud early in the season to maximize root:shoot ratios, which has been shown to increase seedling success. Seeds from a mixture of maternal trees in Utah and Idaho are available in our freezers from past years of collections. Even seeds from 2014 have recently shown high rates of germination (>95%). Seeds will be sown in April 2018 and seedlings will be ready for planting in fall 2018. To ensure sufficient numbers of high quality seedlings, we will grow an additional 1000 seedlings. Excess seedlings will be donated to landowners in the Brian Head area. Task 2: Site selection. Based on our previous work with aspen seedlings, we will use a combination of GIS, early summer imagery, and site visits to choose five sites which are likely to retain soil moisture from winter snowmelt into the summer months. Sites with obvious pocket gopher activity will be avoided. Task 3: Exclosure construction and site preparation. At each of the five sites, we will construct a 30x30m exclosure, 8' tall, using game fencing, t-posts at 8' spacing, and Easy Fence H-braced corners. In our previous work on Cedar Mountain, this construction design was shown to be durable over several winters of heavy snow. Exclosures will be constructed during the summer 2018. Site preparation will include glyphosate treatment if necessary to reduce competing regenerating vegetation. Task 4: Seedling planting. Seedlings will be planted in September or October 2018. Fall planting will allow seedlings to take advantage of spring moisture in 2019 before the sites are accessible. All seedlings will be watered at planting, and will be planted in staked Vexar tubes to minimize herbivory. Four of the exclosures ("Silviculture plots") will be used to test operational planting treatments well within the fire boundaries. The fifth exclosure ("WUI plot") will be used as a demonstration plot for a planting within the fire boundary and near a structure (e.g. a cabin or lodge) with available irrigation water. At each site a total of 576 experimental seedlings and 80 border trees will be planted within the exclosure and 200 will be planted outside the exclosure (total of 856 seedlings/plot). All seedlings will have 1m spacing. The 4 Silviculture exclosures will be divided into 36 blocks of 16 seedlings. We will randomly assign 4 block types (shade/no mulch, shade/mulch, no shade/no mulch, no shade/mulch), with 9 replicates per block type and 16 seedlings per block. Shading treatments will use either shade cards or coarse woody debris, placed to provide shade from the southern aspect. The 200 seedlings planted outside each exclosure will be located on similar substrate, slope, and aspect as the exclosed seedlings. These seedlings will be divided into the same 4 block types as the exclosed trees, with two replicates per block type and 25 trees per block. The WUI plot will be divided into 16 blocks, and blocks will be randomly assigned to 4 plot types, with 4 replicates per plot type: no treatment, mulching only, irrigation only, and mulching + irrigation. An interpretive sign will be placed on the WUI plot.

All plots will be monitored as soon as access is possible in the Spring 2019, and again in July and October 2019. At each of these intervals, the condition, height, maximum branch length, and root collar diameter will be measured on each seedling. In the case of mortality, the putative cause will be noted (herbivory, drought stress, disease). These measurements will be repeated annually for a minimum of 3 years. A statistical analysis and summary of the data will be compiled and reported annually. Annual reports, including monitoring results and project photos, will be uploaded to the WRI project website.

US Forest Service (Stanley Kitchen, co-PI) Utah Division of Wildlife Resources (Ashley Green) -- to provide support for exclosure installation New Mexico State University (Harrington Forestry Research Center at Mora; Owen Burney) If funded, we will contact landowners in or near the Brian Head fire footprint to inform them about our work.

Project results and recommendations will be communicated with state and federal land managers and landowners through research publications, extension publications, and webinars. Recommendations will include elements that can be incorporated into forest plans, wildlife management plans, and other resource management plans.

If aspen restoration in post-fire landscapes can be improved as a result of our project, these landscapes will offer better forage and shelter to domestic livestock.

07/01/2018

12/31/2019

2020

The project was designed to quantitatively assess the benefits of the following variables in post-fire restoration planting protocols for aspen: site selection, addition of biochar, nursery pot size, the use of coarse woody debris, and exclosures to minimize ungulate herbivory. Task 1: Seedling production. Aspen seedlings were produced in the Harrington Forestry Research Center in Mora, New Mexico. This facility has successfully produced many aspen seedlings in recent years, and has experience using aspen seedlings for reclamation of mined lands. Aspen seedlings were grown in either D16 or D40 pots (see below) and were induced to set bud early in the season to maximize root:shoot ratios, which has been shown to increase seedling success. Seeds from a mixture of maternal trees in Utah and Idaho were used to create a seed mixture which was sown in early May 2018 for planting in fall 2018, although planting was delayed until late summer 2019 (see below). Task 2: Site selection. Based on our previous work with aspen seedlings, we used a combination of GIS, early summer imagery, and site visits to choose five sites in the Brian Head fire footprint which were likely to retain soil moisture from winter snowmelt into the summer months. Sites with obvious extensive pocket gopher activity were avoided. We chose three sites on private land within the Brian Head fire footprint. Three sites had undergone salvage logging near the town of Brian Head and two sites were unlogged and located on the National Forest near Brian Head: Salvage logged sites: Salvage site #1: N. 37.710296 W. -112.840533, 2901m Salvage site #2: N. 37.716507 W. -112.829559, 2394m Salvage site #3: N. 37.715028 W. -112.829306, 2952m Unlogged sites: Unlogged site #4: N. 37.69320 W. -112.76354, el. 2988m Unlogged site #5: N. 37.70377 W. -112.75915, el.3115m Task 3: Exclosure construction and site preparation. At each of the five sites, we hired a Utah Conservation Corps crew to construct a 30x30m exclosure, 8' tall, using Tenax elk fencing. At sites #1-3, we used metal corner posts and 10' tposts at 8' spacing. At sites #5 and 6, fencing with t-posts was not approved by the USFS because archaeological clearance could not be obtained in time for construction. Exclosure with Tenax fencing around trees was attempted in the summer 2018 but proved to be too unstable and risky with burned/fragile snags by spring 2019, so those sites were abandoned and the fencing material removed. Exclosures on sites #1-3 were constructed during the summer 2018. Site preparation included spot treatment with glyphosate and hand weeding to reduce competing regenerating vegetation. Sites #1-3 were divided into plots as shown in Figures 1-3. Plots were arranged to minimize adjacent plot types and spread plot types across the sites. For "logs" sites, charred logs were moved from onsite into the plots (Figure 4). Task 4: Seedling planting. Seedlings were scheduled to be planted in October 2018, but an unusual early snowfall prevented access. Instead, the nursery held the seedlings through spring 2019 in a dark enclosure to delay budburst, and the seedlings were top-pruned and allowed to re-sprout prior to planting in late July 2019 to maximize root:shoot ratios. For "biochar" sites, approximately 1/4 cup of biochar was added into the planting hole at the time of planting. For "pot size" plots, trees in differing sized pots (D16 or D40; 16 and 40 cc, respectively) were planted in an alternating pattern within plots in sites #2 and 3 (Figure 2). Because planting aspen seedlings for restoration is uncommon, it is unknown whether larger root systems (D40) might be beneficial to seedling survival, even though these larger pots might be less efficient operationally for planting. Control plots had no treatment although any large logs on these plots were removed. A newly planted plot is depicted in Figure 5. In all, 1120 aspen seedlings were planted in sites #1-3 in late July 2019. Additionally, 400 ponderosa pine (Pinus ponderosa) seedlings in SC10 pots, remaining from a similar study on Cedar Mountain, were planted in an exclosure adjacent to site #2 in late July 2019. These seedlings were also grown at the Harrington Forestry Research Center. This was an opportunistic addition to the project conducted in collaboration with Tom Kolb and Aalap Dixit from Northern Arizona University. The elevation of the planting sites is near the high end of the current distribution of ponderosa pine across its range, including southern Utah. However, as climates shift to a hotter and drier regime in western landscape, ponderosa pine may be expected to move into higher elevations, and may be a good candidate for "assisted migration". Like aspen, ponderosa pine is a fire-adapted species and pulses of natural regeneration frequently occur following fires. Vexar tubing was not used to protect any of the planted seedlings, as originally planned, because of the heavy snow loads observed in the winter of 2018-19. This snow load damaged the Tenax fencing on exclosures, and we were concerned that the Vexar tubing would damage seedlings during the winter. Planted aspen seedlings were marked with large colored paper clips (with different colors denoting plot type or pot size) to distinguish planted trees from subsequent suckers emerging from aspen roots extending from adjacent areas. Soil moisture from monsoonal rains at the time of planting was high enough that additional irrigation was not necessary. However, the monsoonal moisture did not persist, and seedlings were irrigated in mid-August 2019. The City of Brian Head provided a water truck and volunteer driver for this irrigation. Seedlings left over after planting were donated to Brian Head residents. Contact information was collected from these residents, and a follow-up questionnaire about seedling survival will be administered at the end of the 2020 growing season.

The purpose of this pilot project was to determine whether nursery-grown aspen seedlings could be established by planting in a recent fire footprint, and whether planting seedlings near logs or with the addition of biochar would help retain soil moisture and improve seedling survival. These are important questions because aspen stands in Utah are experiencing dramatic declines in many areas, and because fire footprints may present an opportunity to restore these forests. Very little is known at this point about the utility of nursery-grown aspen seedlings in post-fire restoration efforts, but this could be a way to increase genetic diversity, bring in drought-adapted stock, and restore aspen to areas where it has been lost due to conifer encroachment. As of June 2020, the aspen seedlings planted in three sites in the Brian Head fire footprint had survival rates ranging from 65% to 84%. Survival was lowest in plots where seedlings were planted adjacent to logs. This result was unexpected since logs should increase retention of soil moisture, and soil moisture was expected to be a significant source of mortality. Interestingly, the high mortality among seedlings planted near logs was largely associated with above-ground small rodent herbivory in sites #1 and 3, as evidenced by scat piles under logs and gnawing marks on stems (Figure 6). The logs likely provided predation shelter for the rodents. The effect was most pronounced in site #1, where mortality rates were 70% to 81% in plots with logs, but 18% to 23% in plots without logs. High mortality rates were coincident with signs of rodent damage (Tables 1-3). In site #2, little evidence of rodent herbivory was present on plots with logs, and mortality rates in those plots was lower (as expected) than mortality rates in plots without logs. The addition of biochar to planting holes had little effect on seedling survival rates (Table 4). The size of the planting pots (D16 vs D40) also had no effect on seedling survival rates (Table 4). Surviving aspen seedlings were generally in good condition as of June 2020. If these seedlings survive another year they would be expected to develop more extensive root systems, and should begin to send up suckers of their own as they become established. At that point, their probability of survival through climate fluctuations and even subsequent low to medium severity fire should be quite good. They will remain vulnerable to rodent herbivory and (when exclosures are removed) ungulate herbivory for the next few years. Another surprise was the high survival rate of ponderosa pine seedlings at this high-altitude site. We found that first-year survival rates were approximately 90% for these seedlings, although seedlings planted from the same nursery stock on Cedar Mountain (~2800m, ~45km SSW) experienced near 100% mortality due to drought and rodent damage in the same year. This finding suggests that 'assisted migration' of ponderosa pine seedlings sourced from lower elevations may be a viable strategy for post-fire forest restoration at higher altitudes, given the anticipated impact of climate change (tending toward hotter, drier conditions). In both aspen and ponderosa pine, however, longer-term survival data will be important to obtain.

Overall, seedling survival rates observed in our plots during the first year were high enough to warrant pilot studies in larger areas. However, our findings indicate that traditional strategies to protect planted tree seedlings from soil moisture loss (e.g. planting near logs) may actually increase vulnerability to rodent herbivory in aspen. This is a novel and unexpected finding, and suggests that other aspects of site selection (e.g. absence of evidence of rodent presence, location in low-lying areas which collect runoff or snowmelt) may be especially important in seedling-based restoration for aspen. Our findings of high survival rates among ponderosa pine seedlings is also encouraging and informative, and warrants further study to assess long-term survival at higher altitudes. Overall, our results suggest that post-fire restoration at higher elevations in Utah with both aspen and ponderosa pine seedlings could hold promise in the future. Both aspen and ponderosa pine seedlings will continue to be monitored in fall 2020 and in future years. Survival in 2020-2021 will be especially important since seedling roots will be extending past the planted root mass and becoming established. Additionally, the survival of aspen seedlings donated to landowners in the Brian Head area will be assessed in late 2020.