Conserving Biodiversity and Sustaining Ecosystem Services in the Anthropocene: Understanding the Social–Ecological Legacy of Acid Rain in the Adirondack Park (USA)

Abstract The Adirondack Park of northern New York State is the largest and oldest protected area in the contiguous United States but is also globally recognized as a “hot-spot” for chronic acid rain pollution of forests, lakes, and streams. Recent progress in capping industrial emissions has resulted in dramatic reductions in acid deposition, which is now approximating levels similar to those prior to the Industrial Revolution. This article describes how over a century of chronic acid pollution has shaped the biodiversity and ecosystem services of the lands and waters of the Adirondack Park. Evidence of acid rain impacts on the biodiversity of Adirondack forests is mixed, with the most obvious negative effects on calcium-dependent species of plants, invertebrates, and songbirds. Yet other key forest species, such as the eastern redback salamander, have exhibited more tolerance of acidification than expected. Adirondack fisheries have also been degraded by reductions in pH and disruption of aquatic food webs. In terms of ecosystem services, acid-impaired Adirondack hardwood forests provide a lower quantity and quality of numerous benefits—wood products, greenhouse gas regulation, maple syrup, and fall foliage—amounting to roughly half of the economic value of forests where acid rain has had little or no impact. Looking ahead, forestry practices that were developed to sustain highly valuable tree species over harvest rotations may no longer have successful outcomes on severely acidified soils, due to the absence of regeneration available to form the next cohort. Acid rain has had little impact on the potential for Adirondack watersheds to provide safe drinking water but has significantly degraded the value of recreational fisheries in lakes. Although major reductions in acid pollution can allow recovery of ecosystems and their many services, the trajectories and endpoints of recovery will vary in complex ways, with biological recovery lagging behind indicators of chemical recovery. The legacy of acid rain will continue to the shape the Adirondack Park as it enters an Anthropocene that bring a warming climate, increasingly extreme weather, exotic pests and pathogens, and invasive species, among other drivers of change. The Adirondack “experiment” and its ongoing challenges with acid rain offer lessons on conservation in a rapidly changing Anthropocene world.