Critical loads of atmospheric deposition help decision-makers identify levels of air pollution harmful to ecosystem components. But when critical loads are exceeded, how can the accompanying ecological risk be quantified? We use a 90% quantile regression to model relationships between nitrogen and sulfur deposition and epiphytic macrolichens, focusing on responses of concern to managers of US forests: Species richness and abundance and diversity of functional groups with integral ecological roles. Analyses utilized national-scale lichen survey data, sensitivity ratings, and modeled deposition and climate data. We propose 20, 50, and 80% declines in these responses as cut-offs for low, moderate, and high ecological risk from deposition. Critical loads (low risk cut-off) for total species richness, sensitive species richness, forage lichen abundance and cyanolichen abundance, respectively, were 3.5, 3.1, 1.9, and 1.3 kg N and 6.0, 2.5, 2.6, and 2.3 kg S ha⁻¹ yr⁻¹. High environmental risk (80% decline), excluding total species richness, occurred at 14.8, 10.4, and 6.6 kg N and 14.1, 13, and 11 kg S ha⁻¹ yr⁻¹. These risks were further characterized in relation to geography, species of conservation concern, number of species affected, recovery timeframes, climate, and effects on interdependent biota, nutrient cycling, and ecosystem services.

Smoke from wildland fire is a significant concern to resource managers who need tools, knowledge, and training to analyze, address, and minimize potential impacts; follow relevant rules and regulations; and inform the public of possible effects. Successful navigation of competing pressures to appropriately use fire on the landscape to manage fire-adapted and fire-dependent ecosystems, while protecting public health and other air quality values, depends on credible science and tools conceived of and developed in partnership between managers and the research community. Fire and smoke management are made even more complex by the current condition of ecosystems as a result of fire exclusion and the future implications of a changing climate. This chapter describes the scope of smoke management, social and regulatory contexts, and pathways through which scientific information and tools can improve the accuracy and timeliness of management and communication with the public.

There is an inseparable connection between the health of soils and the well-being of people. Disturbances—changing climate and environment, invasive species, increasing wildfire severity and frequency, land management practices, and land use changes—are affecting soil health in complex ways that are only partially understood. This assessment provides a baseline for soil health by synthesizing the most recent research on the properties and processes characterizing forest, rangeland, wetland, and urban soils at regional and national levels. It also summarizes the current state of knowledge about the effects of historical and ongoing disturbances. Finally, it highlights the technologies, networks, and outreach programs central to future research on, and monitoring and management of, the nation’s soils. The state of the knowledge indicates that adverse changes to soil properties could, in the long term, undermine the primary ecosystem services provided by soils: abundant water, food, and fiber and moderation of climate warming. Research that can further explain the underlying principles of soil science and the effects of disturbances is needed to inform policies and management practices to optimize soil health on a broad scale and support human health and welfare through the twenty-first century.