Our summary from SNAMP: 31 integrated recommendations

The following forest management recommendations consider the SNAMP focal resources (forest health, water, wildlife), as well as public participation, as an integrated group. These recommendations were developed by the UC Science Team working together. Although each recommendation was written by one or two authors, the entire team has provided input and critique for the recommendations. The entire UC Science Team endorses all of these integrated management recommendations. Click at the bottom of the post for the full description of each recommendation. 

Section 1: Integrated management recommendations based directly on SNAMP science

Wildfire hazard reduction

1. If your goal is to reduce severity of wildfire effects, SPLATs are an effective means to reduce the severity of wildfires.

Strategic siting of fuel treatments places treated areas in locations where the topology of fire (i.e., biophysical conditions that contribute to adverse wildfire effects) is the highest. Owing to the complexity of modeling fire and fuels treatment across real landscapes, fuels treatment project design is often based on local knowledge of both the project area and past fire patterns. Managers at the two SNAMP study areas designed and deployed effective SPLAT treatments that differed in their spatial characteristics: the northern site had more of a clumped treatment allocation whereas the southern site was more dispersed. In modeling, both were effective in reducing the potential for flame lengths > 6.5 ft (2 m), which is related to conservation of large, older trees. Our modeling, modeling by others, and empirical studies by others have demonstrated that SPLAT networks will reduce the risk of uncharacteristically severe fire. 

SPLAT impacts on forest ecosystem health 

2. If your goal is to improve forest ecosystem health, SPLATs have a positive effect on tree growth efficiency.

Forest growth efficiency, defined here as the basal area increment per unit leaf area, is a proven indicator of forest health (Waring 1983). The reductions in tree basal area and density related to SPLATs implementation increased the modeled growth efficiency at both Last Chance and Sugar Pine. However, the magnitude of the improvement in growth efficiency depends on both the extent and intensity of the SPLATs treatment and on the structure of the pre-treatment forests. The site that started with the higher basal area and canopy cover (i.e., Sugar Pine) showed a larger relative increase in growth efficiency from SPLATs, even though by some measures the treatment impact on forest structure was less.

SPLAT impact assessment

3. If your goal is to integrate across firesheds, an accurate vegetation map is essential, and a fusion of optical, lidar and ground data is necessary.

Lidar data can produce a range of mapped products that in many cases more accurately map forest height, structure, and species than optical imagery alone. Our work indicated that the combination of high-resolution multi-spectral aerial/satellite imagery with lidar is very helpful in mapping vegetation communities as well as characterizing forest structure zones.

4. If your goal is to understand the effects of SPLATs, lidar is essential to accurately monitor the intensity and location of SPLAT treatments.

Lidar data can effectively penetrate the forest canopy and can be used to accurately detect forest understory changes. Our work indicated that the use of lidar-derived vegetation structure products (e.g., canopy cover and vegetation height) significantly outperformed the aerial image in identifying the SPLAT treatment extent and intensity. 

SPLAT impacts on California spotted owl and Pacific fisher

5. If your goal is to maintain existing owl and fisher territories, SPLATs should continue to be placed outside of owl Protected Activity Centers (PACs) and away from fisher den sites, in locations that reduce the risk of high-severity fire occurring within or spreading to those areas.

Spotted owl PACs contain about 310 acres (~125 ha) of the best habitat around owl nest and roost locations, and as such, they protect the core area of use within owl territories. Furthermore, owls have consistently used PACs for nesting and roosting over long time periods (up to 24 years; Berigan et al. 2012). Fisher den buffers contain 700 acres (~285 ha) of the most suitable habitat around known den sites, and reuse rates support the importance of these sites. Thus, the U.S. Forest Service should continue its current policy that restricts timber harvest within these sites, and PACs should remain a cornerstone of the agency’s spotted owl management strategy. In addition, SPLATs should be designed to limit the potential for high- severity fire to spread into PACs and den buffers.

6. If your goal is to maintain landscape connectivity between spotted owl territories, SPLATs should be implemented in forests with lower canopy cover whenever possible.

Recent studies have shown that spotted owl populations in the Sierra Nevada have declined by as much as 50% over the last 20 years (Tempel et al. 2014a). Therefore, we believe a cautious approach is warranted regarding the placement of SPLATs with respect to existing owl habitat. Spotted owl territory fitness and occupancy were strongly correlated with the amount of high- canopy-cover forest within spotted owl territories (Tempel et al. 2014b), where we defined ‘high- canopy-cover forest’ as forest dominated by trees ≥ 12 in (30.5 cm) dbh and having ≥ 70% canopy cover. Thus, SPLATs should target younger forests or forests with lower canopy cover when possible, recognizing that the ultimate objective of SPLAT placement is to significantly modify wildfire behavior.

7. If your goal is to increase owl nest and fisher den sites, retain oaks and large conifers within SPLAT treatments.

Fishers den exclusively in cavities, while owls nest in both cavities and platforms. Both species consistently utilize larger diameter trees that exhibit some form of structural decay or damage, and levels of reuse indicate that these structures may be a limiting factor. Cavities suitable for den or nest sites may take decades to centuries to develop; therefore, it is critical not only to protect current structures but to enhance the development of these structures over time. Protection of these structures may take the form of retention during thinning activities as well as raking away duff or other ground fuels during burning operations, particularly where a basal hollow may allow ground fire access into the tree. Spotted owls will sometimes use areas without large trees if there are suitable nest sites available and if they are adjacent to high-canopy-cover forest.

8. If your goal is to maintain fisher habitat quality, retention of canopy cover is a critical consideration.

SNAMP data, as well as numerous other research projects, consistently indicate that contiguous canopy cover is an important factor in fisher habitat selection. Within the SNAMP key watersheds, predicted fisher occupancy increased from 0.65 to 0.80 as the proportion of the landscape with >40% canopy increased from 0.25 to 0.75. Wherever possible, SPLATs should emphasize the reduction of surface and ladder fuels and retain dominant trees. Where high fire risk requires canopy reduction, SPLATs should be placed such that they provide protection for dense canopy refuges, and canopy should be retained above 40% at the landscape scale.

9. If your goal is to increase fisher foraging activity, limit mastication and implement more post-mastication piling and/or burning to promote a faster recovery of the forest floor condition.

The SNAMP fisher assessment identified a short-term reduction in fisher occupancy following non-commercial fuel reduction, particularly mastication. This reduction is likely associated with the loss of understory and the residual matrix of small to mid-sized woody debris scattered on the landscape. Where feasible, post-mastication burning or some other follow-up treatment would help promote a faster recovery of natural forest floor conditions and facilitate fisher activity. Dispersing smaller mastication projects across the landscape, to insure that an animal can move freely around them, could also help minimize negative impacts and retain fisher activity in an area.

10. If your goal is to understand SPLAT effects on owl and fisher, it is necessary to consider a larger spatial scale than firesheds.

Both wildlife teams found a limited number of animals within the original study areas at Last Chance and Sugar Pine and thus had to expand their study areas to obtain sufficient sample sizes (see Popescu et al. 2012). Both the owl and fisher have large home ranges relative to the spatial scale of a fireshed, and to understand how SPLATs may affect populations of these species (as opposed to individual animals or territories) will necessarily require study areas that incorporate multiple firesheds.

SPLAT impacts on water quantity and quality

11. If your goal is to detect increases in water yield from forest management, fuel treatments may need to be more intensive than the SPLATs that were implemented in SNAMP.

Model results show that reduced vegetation density from the implementation of SPLATs may not be enough of a vegetation change to definitively observe an increase in water yield. Fireshed scale simulations do show small increases in precipitation being routed to the stream outlet following treatments. The increases in water yield might not be large enough to be easily measured and likely require a control structure grounded in bedrock for more precise streamflow observations. The small reductions in vegetation from treatments were temporary, with regrowth exceeding the original pre-treatment vegetation density in the first decade. Maintaining any water yield increases from light vegetation treatments would either require frequent application or more intensive treatments to extend water yield increases over time. However, vegetation in the treated catchments remained at lower densities compared to untreated forest conditions, with the increased water yield from implementation of SPLATs persisting relative to catchments without vegetation treatments.

12. If your goal is to maintain water quality, SPLATs as implemented in SNAMP have no detectable effect on turbidity.

Given that monitored water chemistry parameters (dissolved oxygen, temperature, and turbidity) are within healthy ranges for the SNAMP watersheds, the most elevated risk to water quality in these aquatic systems is sediment movement resulting from forest treatments. Stream turbidity patterns indicate that in-channel erosion is the main sediment source, with accumulation and depletion cycles tied to low and high flow periods – results similar to previous regional monitoring. Channel bed movement patterns suggest that under stable forest conditions (no treatment or fire), the stream channel experiences seasonal changes in storage of bed material, but remains stable on an inter-annual basis. Increases in sediment transport from treatments would then likely be related to increases in discharge. The post-treatment monitoring period was completed during a second consecutive year of drier than normal conditions. Additionally, the implemented treatments were light and located a significant distance from stream channels, in accordance with standard forest practices. These treatments were not intensive enough to produce an increase in discharge during the low precipitation year and show that SPLATS as implemented in SNAMP had no detectable effect on turbidity when followed by dry conditions. 

Stakeholder participation in SPLAT implementation and assessment

13. If your goal is to increase acceptance of fuel treatments, employ outreach techniques that include transparency, shared learning, and inclusiveness that lead to relationship building and the ability to work together.

Throughout the literature, across other projects, and in SNAMP, transparency, shared learning, and inclusiveness have been found to be critical for building relationships that can lead to collaboration. A collaborative atmosphere is needed before conflicts about fuel treatments can be discussed and their efficacy tested effectively enough to promote acceptance. Our results show that, in SNAMP, the many and varied outreach activities where participants learned together in an inclusive and transparent setting ultimately contributed to improved relationships even between those traditionally opposed to each other. In this context, the acceptability of fuels treatments by groups was tested, thoroughly viewed and discussed by participants, and ultimately preferred as a management strategy by most SNAMP participants. Through the increased engagement with Forest Service District Rangers and other staff, our data show a dramatic increase in learning and understanding about the Forest Service and its constraints. This could help improve collaboration with the agency going forward, as long as the agency continues a strong effort to interact sincerely and transparently with the public. As has been found in the literature, facilitation was key to making it work, as was reaching out to people in different walks of life; holding a meeting and expecting people to show up was not enough. Participation Team personnel lived in local communities and brought information to meetings convened in local communities, including those of Boards of Supervisors, local environmental groups, and locally important natural resource industries. Finally, emphasis needs to be on multi-directional learning: stakeholders, including scientists and Forest Service managers, learn from other stakeholders. Even in a “top down” agency-initiated process like SNAMP, emphasis on shared learning helped build social capital and the ability to work together.

14. If your goal is the increased acceptance of fuel treatments, the public needs to understand the tradeoffs between the impacts of treatments and wildfire.

In SNAMP, participants differentiated between short and long term impacts of treatments and fire, and much of the UC Science Team’s work attempted to address these details. This deep level of learning and discussion was needed for participants to consider the tradeoffs that are part of forest management. Face-to-face meetings with scientists were an important part of helping the public learn about the effects of treatments, and helping the scientists appreciate the concerns and interests of the other stakeholders. Scientists were available to answer questions from the public through multiple channels: annual meetings, integration meetings, and the interactive website. Field trips were especially important, both in building relationships and understanding what occurred on the ground. Integration meetings allowed small groups of stakeholders to focus on a particular aspect of the project to discuss findings and their implications in-depth. SNAMP personnel living in the local communities were also available to stakeholders on a regular basis to answer questions, and to learn from the communities and the agency. Overall, within the adaptive management model, it is important to emphasize stakeholder learning and participation whenever possible through all aspects of the process, from the selection of foci for scientific investigation to the interpretation of results.

Successful collaborative adaptive management processes 

15. If your goal is to establish a third party adaptive management project with an outside science provider, the project also needs to include an outreach component.

A third party science perspective is often sought in controversial resource management matters where there is not only a lack of knowledge (hence the need for scientific investigation) but also a shortage of trust (hence the need for a third party). This third party information can help to support the mutual learning component of adaptive management. At the onset of SNAMP, the investment in outreach was recognized as a priority. At the conclusion of SNAMP, the investment in public participation via the UC Cooperative Extension proved invaluable. Thus, a specific commitment of staffing and resources to extend the insights from the third party to all participants is essential to the success of a third party adaptive management project.

16. If your goal is to develop an engaged and informed public, you need to have a diverse portfolio of outreach methods that includes face to face meetings, surveys, field trips, and web-based information.

Segments of the public differ in their proximity, understanding of issues, and ability to participate in national forest management. To involve the broadest segment of the public in SNAMP, the broadest methods of participation were used. These included outreach events that allowed people to participate occasionally or regularly, and methods that accommodated participation both locally and from afar (through web technologies such as hosting a comprehensive website, producing webinars, and webcasting meetings). 

17. If your goal is to understand or improve outreach effectiveness, track production, flow, and use of information.

Some of the factors that can contribute to the success of collaborative adaptive management – such as social learning, open communication, and trust - are built upon a foundation of the open exchange of information about science and management between participants and the public. Currently, there exist opportunities to develop strategies for increasing the exchange of information, as well as to track information flow in such contexts. We recommend what we used in SNAMP: a mixed methods (citation analysis, web analytics, and content analysis) approach borrowed from the information processing and management field to track and facilitate the flow and use of digital information. We archived meeting notes, attendance, publication records, website statistics, and other SNAMP outputs throughout the life of the project. Analysis of these data sources showed SNAMP facilitated a dramatic transfer of scientific knowledge.

18. If your goal is to engage in collaborative adaptive management at a meaningful management scale, secure reliable long term sources of funding.

Forest management decisions often address processes at spatial and temporal scales that challenge empirical efforts to gain new knowledge. Thus, management-relevant science requires long term funding that acknowledges the move towards a landscape-based approach, the uncertainty in operational schedules associated with implementing treatments, and the consequences of delays and funding reductions on project outcomes. The SNAMP workplan never made provisions for "closing the adaptive management loop" by tracking the use of the new information to revise management actions as needed after the assessment was finished. This omission was noted at the onset, but extending SNAMP to “close the loop” would have extended the project beyond what was deemed feasible to fund. Thus, a key recommendation from SNAMP is to secure the long term funding required to accommodate delays and complete the adaptive management cycle at the outset.

19. If your goal is to maintain a successful long-term collaborative adaptive management process, establish long-term relationships with key people in relevant stakeholder groups and funding agencies.

Consistency and inclusivity in participants are important goals. The principle that all interested parties could join the collaboration at any time was important in the SNAMP process. New participants add viewpoints and information as well as broaden the group that will learn from and participate in the project. The SNAMP website provided extensive background and historical information of use to these new stakeholders, making it easier for new participants to catch up. On the other hand, consistency is crucial from funding agency contacts and science providers as well as lead stakeholders. In general, there was little turnover on the UC Science Team, a bit of change within the participant groups, and a lot of new faces within the Memorandum of Understanding (MOU) Partner contacts over the 10 years of the project. SNAMP struggled, more than once, with funding constraints. Turnover in agency leadership, as well as in administrative or accounting staff, intensified the difficulty of these funding crises. Multi-year projects such as SNAMP need champions within the participating agencies in order for the projects to maintain internal interest and funding. During these fiscal crises, the lead nonprofit stakeholders came to the defense of the project and strongly encouraged the agencies to continue funding. A strong commitment to the project from long term stakeholders was necessary to continue the project. 

Section 2: Looking forward - Integrated management recommendations based on expert opinion of the UC Science Team

Implementation of SPLATs

20. If your goal is to maximize the value of SPLATs, complete treatment implementation, especially the reduction of surface fuels.

Fuels can be divided into four classes: ground, surface, ladder, and crown. Ground fuels are the decomposing organic layer on the soil surface and do not contribute to fireline intensity or fire spread. Surface fuels are the dead and down woody materials, grasses, forbs, and small shrubs that contribute to flaming combustion and the potential for crown fire. They are therefore the most important fuel class when reducing fire hazards in forests. Ladder fuels are small trees and tall shrubs that can provide vertical fuel continuity to move a fire from the surface to tree crowns; they are the 2nd most important fuel layer regarding fire hazards in forests. Crown fuels are those in the overstory and do not contribute a large portion of fire hazards in California forests. Effective forest fuel treatments will therefore target surface and ladder fuels. 

21. If your goal is to efficiently reduce fire behavior and effects, SPLATs need to be strategically placed on the landscape.

To efficiently reduce fire behavior and effects, fuel treatments need to be strategically placed on the landscape (the first letter in SPLAT stands for strategic). There are many ways that the placement of fuel treatments can occur in forests: near roads that have good fire suppression access, near the urban-wildland interface to protect people and homes, on gentle slopes that machines can safely operate on, between patches of important late-seral habitat, and in areas with an excessive density of shade tolerant species such as white fir. While all of these are sound reasons to install fuels treatments, none of them addresses the topology of fire and therefore would not lead to a strategic treatment placement. Placement of fuel treatments for the above reasons would be classified as random, and approximately 50% of the landscape would need to be treated to reduce fire behavior and effects. In contrast, if approximately 20% of an area received a strategic placement of fuel treatments it would perform similarly to the 50% randomly placed system. It is possible to exclude some parts of a landscape for consideration in the strategic placement of fuel treatments, but when this becomes excessive it is not possible to produce a SPLAT design. 

22. If your goal is to improve SPLAT effectiveness, increase heterogeneity within treatment type and across the SPLAT network.

Reduction of surface and ladder fuels will reduce fire hazards in mixed conifer and ponderosa pine forests. Restoration focuses on re-establishing the composition, structure, pattern, and ecological processes necessary to facilitate ecosystem sustainability, resilience, and health under current and future conditions. One way a SPLAT network can be designed to incorporate restoration objectives is to increase heterogeneity of treatment areas. Creating treatment areas that includes clumps of trees, individual trees, and openings will increase resiliency and provide diverse habitats. Fires interacting with this type of structure will produce mixed effects including the mortality of trees, but forests in these areas will still be conserved into the future. Allowing some forested areas with high hazards (high canopy cover, high snag, and large woody debris) within a matrix of low to moderate hazards from installed SPLATs may conserve forest ecosystems into the future.

Forest ecosystem restoration

23. If your goal is to restore Sierra Nevada forest ecosystems and improve forest resilience to fire, SPLATs can be used as initial entry, but fire needs to be reintroduced into the system or allowed to occur as a natural process (e.g., managed fire).

Installing an initial SPLAT network (as the Forest Service did in the SNAMP treatment firesheds) will reduce potential fire behavior and effects when the landscape eventually burns. SPLATs can also be used to anchor managed wildfire or large scale prescribed burning operations in a fireshed (North et al. 2012). A SPLAT network would moderate fire effects during burning, and this should result in increased forest resilience to fire. Allowing fire to return to these ecosystems as a natural process is a critical objective for the long term sustainability of forests. 

24. If your goal is to manage the forest for long-term sustainability, you need to consider the pervasive impacts of climate change on wildfire, forest ecosystem health, and water yield.

Climate change is already increasing temperatures and reducing the period when snow is on the forest floor in Sierra Nevada forests; these changes will increase the incidence of fire throughout the range. Droughts will increase the populations of native tree-killing insects such as bark beetles, and they could have a massive impact on large, old trees. Development of landscape strategies that increase the resiliency of forests to these expected disturbances is critical. SPLATs are a good first step in this journey. Once areas have received SPLATs, moving some of these landscapes (unroaded, remote) to a lightning fire maintenance regime may be appropriate. The spatial scale of the restoration work needed in the Sierra Nevada is immense. One big operational challenge is how to balance the need for new treatments versus maintenance of existing treatments. Moving some areas that have received SPLAT treatments to lightning fire maintenance would allow managers to continue to treat new additional areas. Since we know that forest ecosystems are dynamic, this journey never ends. Continued use of managed fire, prescribed fire, and mechanical treatments will be necessary for the conservation of the ecosystems of the Sierra Nevada. There is no alternative. 

Management impacts on California spotted owl and Pacific fisher

25. If your goal is to enhance landscape habitat condition for owl and fisher, hazard tree removal of large trees should be carefully justified before removing.

Large trees create cooler microclimates within stands that may benefit spotted owls, and large trees also increase the suitability of intermediate-aged forests for both spotted owls and fisher. These residual trees may allow owls to use intermediate-aged forests for nesting and roosting when they otherwise only use them as foraging habitat. Similarly, fishers frequently use these remnant trees as rest sites in the midst of more intermediate-aged stands.

26. If your goal is to minimize the effects of SPLATs on fisher, SPLAT treatments should be dispersed through space and time.

SPLATs do represent a short-term loss in habitat quality for fishers. Therefore, these costs need to be dispersed in space and time, such that there is not a concentrated reduction in habitat quality in one particular area. SNAMP data indicate that forest restoration / fuel reduction management does reduce fisher occupancy in the short term, with a 47% reduction in occupancy following treatment. However, there was no multi-season impact on the population, indicating that fishers remained in the surrounding area. This is likely due to the fact that fishers have large home ranges, and because the overall percentage of a territory treated at any given time is small (<2% per year), they are able to move around treated areas and remain viable. Furthermore, evidence indicates that treated landscapes become suitable for use again in 5-25 years, depending on the treatment applied. Concentrations of SPLATs in space or time could risk limiting this movement and landscape recovery, while dispersing them helps retain local occupancy.

Management impacts on water quantity and quality

27. If your goal is to optimize water management, consider the range of potential fluctuations in precipitation and temperature.

Even during the short SNAMP study period, precipitation conditions ranged from some of the wettest conditions on record to some of the driest. The response of the hydrologic system to forest management will depend on the specific precipitation patterns exhibited, from a lack of response due to light thinning and low precipitation to a strongly significant response after intensive treatments and high precipitation. When determining if measureable changes in water yield will occur in response to reducing vegetation density, the monitoring period should be of appropriate length to include a range of precipitation conditions. This study was successful in the range of annual precipitation during the pre-treatment period, but only low precipitation years have followed SPLAT implementation. Although this study did not specifically address climate change, regional studies suggest that warmer conditions expected through the end of the century will result in more rain, smaller snowpack storage, and longer growing seasons, leading to higher evapotranspiration loss and lower annual water yield.

Successful collaborative adaptive management processes

28. If your goal is to implement collaborative adaptive management, commit enough time, energy, and training of key staff to complete the adaptive management cycle.

Vital elements to whatever collaborative approach is used include clarification of roles, relationships, and responsibilities for each of the participants in the collaborative effort, development of an explicit decision-making process including a fall-back strategy if decisions cannot be agreed on, and clear definition of the relationship between the group and decision making authority to avoid false expectations. Agencies committing to carry out collaboration should be prepared to commit the staff time and resources to the effort. Staff engaged in collaborative efforts and all participants should receive some fundamental training in effective meeting management and how to practice facilitative behaviors during meetings. Collaboration takes funding, time, effort, and enduring dedication to the process.

29. The role of a third party science provider for an adaptive management program can be realized in a variety of ways.

As a third party science provider, UC Science Team scientists communicated directly with stakeholders as well as the MOU Partners and Forest Service managers. Monitoring and management impact assessment from a source independent of the entity responsible for management is similar to having an independent auditor review the books of a company, and we hypothesize it can increase stakeholder confidence in the information. SNAMP data suggest that stakeholders appreciated this in SNAMP. However, it can be costly. This role could be fulfilled at least partially in other ways, for example, by involving stakeholders in monitoring processes as part of joint monitoring programs, or involving a third agency or group with a reputation for neutrality and no regulatory authority to conduct monitoring and/or research. For example, the Natural Resources Conservation Service is now conducting monitoring for the Bureau of Land Management in some areas. At the least, research and monitoring should be transparent to stakeholders. On public lands today, the public needs to be brought along with management decisions, and part of that is understanding and feeling confident about the results of research and monitoring.

30. If the goal is to implement adaptive management, managers must adopt clear definitions and guidelines for how new information will be generated, shared, and used to revise subsequent management as needed.

Adaptive management, as a concept, has many different definitions. To implement adaptive management, agencies must adopt, for each project at the outset, a clear operational definition and process guidelines for all aspects of the adaptive management cycle. It is important to clarify what information is being developed and how it will be considered in future management decisions. Clear record keeping of what was actually implemented on the ground and the outcomes are essential to success. It is important to document, track, and monitor how information is used in the next management cycle in a public and transparent manner.

31. If your goal is to increase forest health in the Sierra Nevada, we now know enough to operationalize some of the aspects of SNAMP more broadly.

SNAMP and other landscape-scale projects in the Sierra Nevada have demonstrated how to reduce fire hazards and increase forest health. Increasing the spatial heterogeneity of treated areas will also provide important restoration objectives. With this information, it is desirable to operationalize these treatments across the larger Sierra Nevada landscape. There is currently a great need for forest restoration and fire hazard reduction treatments to be implemented at large spatial scales in the Sierra Nevada. The next 1-3 decades are a critical period: after this time it may be very difficult to influence the character of Sierra Nevada forests, especially old forest characteristics.