Chapter 13 - Rehabilitating forest soils after disturbance

Abstract

Abstract The development of a functional soil is fundamental to restoring forest ecosystems following major disturbances such as surface mining. Given that it is much easier to revive soil than it is to create soil, salvaging and replacing topsoil is the simplest and most effective means of restoring a functional soil following disturbance. Soil hydrological function must be restored at both the site level (having soil water retention to support plant growth and soil biota), and landscape level (limiting or enhancing runoff or deep percolation). Practices for restoring water-related functions include avoiding compaction during soil reconstruction, creating rough surfaces to increase infiltration and reduce runoff and designing structures such as drainage swales to convey surface runoff to desired receiving areas with minimal damage. The rates at which organic matter and nutrients accumulate in soils are influenced by the vegetation; nitrogen-fixing plants, broadleaf tree species and grasses build stocks faster than conifer trees. Practices that enhance soil water-holding capacity, aeration and accumulation of organic matter and nutrients also make soils more conducive for soil microbial and faunal communities. The development of the soil biota is largely determined by the rate at which the plant community develops, but can be hastened by applying native soil inoculum to restored sites. Biodiversity can be enhanced at the landscape level by retaining or creating a variety of habitat types within the post-mining landscape, rather than applying a single prescription to the entire site. Practices that promote the hydrological and nutritional conditions that support plant, microbial and faunal communities will also assist in the development of soil structure in rehabilitated mine soils. The development of structure may provide the best indication that a soil has been rehabilitated.