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Rapid environmental changes challenge the resilience of wildlands. The western portion of the Lake Tahoe Basin in California is an important ecological and cultural hotspot that is at risk of degradation from current and future environmental pressures. Historical uses, fire suppression, and a changing climate have created forest landscape conditions at risk of drought stress, destructive fire, and loss of habitat diversity. We prospectively modeled forest landscape conditions for a period of 100 years to evaluate the efficacy of 5 unique management scenarios in achieving desired landscape conditions. Management scenarios ranged from no management other than fire suppression to applying treatments consistent with historical fire frequencies and extent (i.e., regular and broadscale biomass reduction). We developed a decision support tool to evaluate environmental and social outcomes within a single framework to provide a transparent set of costs and benefits. Results illuminated underlying mechanisms of forest resilience and provided actionable guidance to decision makers. Sixteen attributes were assessed in the model after assigning weights to each. We found that removing forest biomass across the landscape, particularly when accomplished using extensive fire-based removal techniques, led to highly favorable conditions for environmental quality and promoted overall landscape resilience. Environmental conditions resulting from extensive fire-based biomass removal also had nominal variation over time, in contrast with strategies that had less extensive and/or used physical removal techniques (e.g., mechanical thinning). Our analysis provides a transparent approach to assess large datasets with complex and interacting variables. Ultimately, we aim to provide insights into the complexities of maintaining optimal conditions and managing landscapes to promote ecosystem resilience in a changing world. [ABSTRACT FROM AUTHOR]

• Understanding forest response to perturbations over long time spans is important. • Designed a decision support tool (DST) to assess five modeled forests over 100 years. • The five modeled forests reflected management developed to explore ecosystem resilience. • DST design yielded a transparent framework to assess ecological variables/perspectives. • We found widescale biomass removal resulted in more favorable ecological outcomes. Forward thinking conservation-planning can benefit from modeling future landscapes that result from multiple alternative management scenarios. However, long-term landscape modeling and downstream analyses of modeling results can lead to massive amounts of data that are difficult to assemble, analyze, and to report findings in a way that is easily accessible to decision makers. In this study, we developed a decision support process to evaluate modeled forest conditions resulting from five management scenarios, across 100 years in California's Lake Tahoe basin; to this end we drew upon a large and complex hierarchical dataset intended to evaluate landscape resilience. Trajectories of landscape characteristics used to inform an analysis of landscape resilience were modeled with the spatially explicit LANDIS-II vegetation simulator. Downstream modeling outputs of additional landscape characteristics were derived from the LANDIS-II outputs (e.g., wildlife conditions, water quality, effects of fire). The later modeling processes resulted in the generation of massive data sets with high dimensionality of landscape characteristics at both high spatial and temporal resolution. Ultimately, our analysis distilled hundreds of data inputs into performance trajectories for the five modeled management scenarios over a 100-year time horizon. We then evaluated each management scenario based on inter-year variability, and absolute and relative performance. We found that management scenarios with a greater emphasis on proactive biomass reduction outperformed management approaches with minimal biomass reduction. These results, and the process that led to them, provided decision makers with insight into forest dynamics based on a rational, transparent, and repeatable decision support processes. [ABSTRACT FROM AUTHOR]

Many forests of the western United States have undergone over one hundred years of anthropogenic impacts that have led to increased tree density, homogenization in forest structure, and accumulation of woody material, which combined with a changing climate pose threats to valued social and ecological features. In California, recent waves of tree mortality and unprecedented large and destructive fires have led to rising concerns about the impact of these disturbances on biodiversity and how forest management actions can mitigate negative impacts. To better understand the degree to which different management scenarios could mitigate the negative impacts of these disturbances on biodiversity, we used a spatially explicit modeling platform to model forest management impacts on habitat for terrestrial vertebrate species in the Lake Tahoe Basin of California and Nevada. Specifically, we modeled how 5 different management scenarios that differed in the type of fuel reduction treatment (e.g., fire and mechanical removal of vegetation) and extent of area treated influenced the amount, value, and distribution of reproductive habitat for the 159 species present in the study area. Our model results suggested that within the study area forest growth was predicted to out-pace disturbance leading to a higher percentage of late seral conditions; however, choice of management strategy impacted the composition and structure of the forested landscape leading to different trajectories for wildlife. In general, scenarios that allowed for more extensive use of fire led to a more equitable distribution of habitat types, whereas extensive thinning by hand and mechanical methods resulted in future forest structure that provided better outcomes in terms of reproductive habitat for wildlife. Our modeling results also suggested that low to moderate management strategies were not likely to change the current trajectory to more dense forests dominated by fewer species. [ABSTRACT FROM AUTHOR]