Forest management under uncertainty: the influence of management versus climate change and wildfire in the Lake Tahoe Basin, USA.

Abstract

Climate change will accelerate forest mortality due to insects, disease, and wildfire. As a result, substantial resources will be necessary where and when forest managers seek to maintain multiple management objectives. Because of the increasing managerial requirements to offset climate change and related disturbances, the uncertainty about future forest conditions is magnified relative to climate change alone. We provide an analytical approach that quantifies the key drivers of forest change-climate, disturbance, and forest management-using scenarios paired with simulation modeling to forecast and quantify uncertainties in the Lake Tahoe Basin of California and Nevada (USA), a montane seasonally dry conifer forest. We partitioned uncertainty among climate change (including associated changes to wildfire and insect outbreaks), forest management (including thinning, prescribed fire, and fire suppression), and other sources using a fully factorial experimental design and analysis of variance. We focused on three metrics that are important for forest management objectives for the area: forest carbon storage, area burned at high severity, and total area burned by wildfire. Management explained a substantial amount of variance in the short term for area burned at high severity and longer term carbon storage, while climate explained the most variance in total area burned. Our results suggest that simulated extensive management activities will not meet all the desired management objectives. Both the extent and intensity of forest management will need to increase significantly to keep pace with predicted climate and wildfire conditions.

Evaluating pathways to social and ecological landscape resilience

“…We Maxwell et al 2022a). These extensions interact through their combined effects on vegetation (mortality and regeneration), fuels, and surficial soils.…”

“…More details on the LANDIS-II modeling can be found in Maxwell et al 2022a, b and the corresponding supplemental information, published in this special issue.…”

“…Note: WUI = wildland urban interface, WEPP = Water Erosion Prediction Project.Decadal summaries of LANDIS-II fire outputs were used to derive three indicators: fire frequency, patch size of high-severity fire, and extent of fire by severity class. SeeMaxwell et al 2022a, b for more details. Upland vegetation health Considers to what extent early, mid, and late seral forests are represented across the landscape compared to modern reference conditions.…”

Modeling the Risk Reduction Benefit of Forest Management Using a Case Study in the Lake Tahoe Basin

“…A full model description and applications to the study area are documented in Loudermilk et al (2014), Kretchun et al (2016), Scheller et al (2018Scheller et al ( , 2019. Detailed results from this LANDIS-II modeling exercise are described in two other studies in this special issue (Maxwell et al 2022a and2022b).…”

Evaluating the effects of alternative landscape management scenarios on three old-forest-associated predators over 100 years in the fire-prone forests of the Sierra Nevada, USA

“…Suppression of wildfire remained at 100% in the WUI-defense zone, but managed wildfire was allowed in all other zones, and prescribed fire was allowed in all zones, with a goal of burning 1300 ha at low to moderate severity annually. Scenario 5 was a fire-focused strategy that combined the modest WUI thinning of Scenario 4 with much greater use of prescribed burning in all zones (425 ha/year) and managed natural ignitions for resource objectives in the general forest and wilderness (see Maxwell et al 2022 for more details on management prescriptions and disturbance processes). Each year of simulation was replicated 10 times to provide an annual range of variability, and used a moderate projection of climate change conditions.…”