Request for Collaborators to Participate in Adaptive Silviculture for Climate Change in the Sierra Nevada

September 01, 2017
A team of managers and scientists working to promote new research at Berkeley Forests are implementing a trial of management alternatives that may feasibly be used at wider scales in the future as a response to climate change impacts in the Sierra Nevada. The alternatives represent fundamentally different climate change impact scenarios: from relatively little to profound. Landowners and managers are invited to become research collaborators by designing and implementing the alternatives on their land. Prescription details are flexible to allow for local considerations, as long as the intent of each treatment is met. The treatments include a control (no treatment over the next 6 years), resilience (conventional stocking levels and structural heterogeneity), resistance (relatively low stocking levels dominated by large trees), and transition treatments (a low stocking level matrix and canopy openings to facilitate the trial of new species plantings).    

Timing of treatments and forest types

Treatments are being planned for installation on various Berkeley Forest sites in the Sierra Nevada. The first installment will be at Grouse Ridge in Nevada County. Installments at Blodgett Forest are being planned for 2018 and 2019. The forest type of Grouse Ridge is Site II mixed conifer, with a dominance of white fir and red fir. It is desirable that treatments at other locations occur by 2019.

Site I or Site II mixed conifer lands are desirable. The study design requires enough space to conduct stand-level research. Stands need to be at least 20 acres in size, with each stand replicated 3 times (4 treatments x 3 replications X 20 acres = 240 acres). Assignment of treatments to stands should be randomized.

Treatments – overall intent

Four treatments will be installed, replicated at the stand level. The treatments are meant to represent a basic suite of plausible approaches that managers may feasibly take to address ongoing and novel stresses in forests related to climatic change. It assumed that future climatic stresses are most likely to impact forests in one or more of the following ways: 1) regeneration failures; 2) mortality related to drought stress; and 3) high severity fires. Our objective is to establish a study that, while placing the highest priority on long-term results (i.e. several decades), also has the capacity to produce study results within the next decade.

Prescriptions for Resilience, Resistance, and Transition Treatments



Management for resilience is meant to have the objective, through silvicultural treatments, of preparing a forest to have the capacity to recover pre-disturbance structure and species composition following a disturbance related to climatic change (e.g. drought related mortality or high severity fire). It is expected that recovery take less than 50 years, assumed to be roughly the time that Sierra Nevada forests have taken to regenerate and recruit sexually mature trees following moderate severity disturbances in the past. It is also expected that some management intervention, such as salvage logging, site preparation, and planting could be part of the recovery process in order to enhance the rate of recovery. In general, management intensity (in terms of frequency and severity of treatment) for the objective of resilience is expected to be in between that of Resistance and Control treatments. This resilience treatment is also thought to be most similar to the conventional approach to management of density and structural heterogeneity currently occurring in the Sierra Nevada on federal and some private lands.

At Grouse Ridge, the following marking guidelines were used:

Mark to a residual basal area of 125 ft2/acre
Higher and lower basal areas are acceptable within stands, to allow for low and high density patches that may be desirable for regeneration and habitat objectives
The majority of plots (>50%) should have residual basal areas within 25 ft2/acre of the target basal area
Increasing relative species diversity should be an overall objective of marking; retaining locally rare species should be a high priority
In general, mark smaller and lower vigor trees preferentially; trees of all size classes may be marked, however, to meet species composition and heterogeneity goals



Resistance, in the case of this study, means having the objective of preparing a forest to resist, without significant change to structure and composition, future disturbances related to climatic change. While some change following a future disturbance may occur, it is assumed that change will be small enough in these treated stands so that the fundamental structure and composition needed to sustainably resist future disturbances remain intact. In general, management intensity is expected to be highest when compared to Recovery and Control treatments. For this scenario it is assumed that, while management interventions will be sufficient to resist future climate impacts, relatively intensive and possibly frequent interventions will be necessary.

At Grouse Ridge, the following marking guidelines were used:

Mark to a residual basal area of 75 ft2/acre
Place a high priority on retaining the largest trees of diverse species (including non-commercial tree species)
Leaf area- as opposed to stem form, is used as a deciding factor of marking; the largest trees with the greatest amount of leaf area are assumed to be the most resistant to future climatic stresses



The Transition treatment represents the objective of actively transforming the composition of a forest into one that is better suited to a future climate that is incompatible with currently occurring species. This treatment will replicate a catalyst disturbance that fundamentally changes the composition and structure of a forest, and the forest is unable to recover back to a forested structure without intervention. In other words, this treatment represents the scenario that the Resistance and Resilience treatments do not meet the objective of maintaining forests as forests. Managers would have to intervene in this scenario by planting non-native species. The objective is to convert treated areas into species compositions that will develop into forested structures and provide at least some of the values that forests currently provide. This will occur through a process of forest removal, replanting, and cultural treatments. The primary experiment in the transition treatment is the planting of alternative tree species. The species to plant and the planting design will be developed by managers and scientists through future collaborations.

At Grouse Ridge, the following marking guidelines were used:

Using group selection, regenerate approximately 10% of the stand area with clearfelling to create canopy openings to plant
Allocate an equal area of canopy openings to 1.0, 0.5, and 0.25 acre openings. Using this approach, there will be n 1.0 acre openings, n x 2 0.5 acre openings, and n x 4 0.25 acre openings
1.0 acre openings will be clearfelled without any retention of commercial or sum merchantable trees
Within 0.5 acre openings, retain two large trees. Retention trees should be at least 24 feet from what will be the surrounding drip line edge following the harvest. Retention trees should also be at least 24 feet from each other. This design is meant to create a diversity of resource availability within the gaps following the harvest. The intent is to provide microclimates that may be necessary to optimize survival for some tree species (i.e. shade tolerant species).
Within 0.25 acre openings, retain one large tree using the same protocol as 0.5 acre openings
In the matrix forest between clearfelled openings, use the same marking prescription as with the transition treatment (residual basal area of 75ft2/acre, maximizing species diversity and large tree retention). 


On Berkeley Forests, a network of permanent plots have been established to provide the minimum data needed to monitor structural and composition effects. Plots are 0.1 acre permanent circular plots. Trees, fuel, regeneration, and standing dead trees are tracked. Plots are on a grid of points spaced 396 feet apart. Collaborators may have their own monitoring protocol that could be sufficient for monitoring. At this point, funding is not available to establish new monitoring networks. Funding such networks will be a target for funding in the future. 

Adapting the Study for Local Environments and Constraints

The intent of the collaboration is to increase the value of the study by incorporating manager insight and to explore other alternatives that may turn out to be the best approach in a future climate that has uncertain impacts. Collaborators are invited to critique the prescriptions above and either replicate these prescriptions, or propose new prescriptions.

Potential collaborators should contact:

Ricky Satomi

Forestry/Natural Resources Advisor

UC Cooperative Extension Shasta County
1851 Hartnell Avenue
Redding, CA 96002-2217