Soils are fundamental to landscape restoration

Abstract Soils are natural bodies, formed by the state factors of physical, chemical, and biological processes operating on geologic parent material over time. Long recognized for their importance to agriculture and forestry, the role of soils in natural systems has been underappreciated. Soils provide important ecosystem services, determined by their natural capital, a function of texture, mineralogy, and organic matter. Our conceptual model for examining soil and landscape restoration is based on the state factors; their interaction produces a mosaic of microhabitats across the landscape. Interest in soil restoration is embedded within a variety of international policy initiatives; forest restoration in particular enjoys much international support since the inception of the Bonn Challenge in 2011. Objectives for soil restoration aim to recover functions by reversing degradation and returning soils to healthy conditions, but the widespread human footprint cannot be ignored. The starting point for restoration can be approached by answering two questions: “Do we have it? and Do we want it?”. This leads to four possible strategies: preserving or eliminating current conditions, or achieving or avoiding some future conditions. Historic examples of large-scale restoration in Northeastern and Southeastern United States, Puerto Rico, Denmark, and South Korea illustrate different trajectories following abandonment of agriculture and recovery of forest vegetation. One critical factor was how much previous land use degraded the soils. Future conditions are likely to differ from current and recent historical conditions due to climate change. Climate change has a significant impact on soils, including decoupling important soil–vegetation linkages resulting in accelerated wind and water erosion. The need today is great for restoring landscapes, with a special focus on stabilization and improvement of their underlying soils, and this need likely will become even greater over the next decades.