About this Research Topic
Forest soils are globally important stores of carbon and are the fundamental agents in maintaining tree growth and diversity. Knowing the physical, chemical and biological properties of forest soils throughout the depth profile is important to improve our understanding of forest greenhouse gas (GHG) exchange and the mechanisms maintaining tree growth and diversity. However, most research to date has focused on the topsoil (often just 0-20 cm or 0-30 cm depth) and forest subsoils have received much less attention. This is largely because surface soils are easier to collect and are likely to be more sensitive to global changes and other disturbances. Although some studies have focused on the differences in carbon (C) stocks and stability, microbial communities, nutrient availability for plant growth, or root biomass and distribution deeper down the soil profile, there are still large knowledge gaps around the physical, chemical and biological properties of subsoils, in particular around the differences in functional roles of topsoils and subsoils. Nevertheless, it is clear that subsoils play an important role in carbon storage, plant nutrient availability and can be sensitive to disturbance. For example, the guest editors found that experimental manipulations of aboveground litter inputs not only affect topsoil C content, but also alter subsoil C content. In addition, subsoil C stocks were also found to decline after forest fires. Therefore, it is urgent for scientists to go deeper underground and investigate how forest soil properties and processes change with depth.
In this research topic, we focus on the roles of topsoil and subsoil in forest functioning, and invite papers investigating processes and properties at different depths throughout the soil profile, including studies of carbon (C) stocks and stability, nutrient availability, microbial biomass and communities, root growth and traits, or other properties and processes relevant to forest ecosystem function. We welcome critical reviews, mini-reviews, opinion, perspective articles and original research articles. The research topic aims to improve our understanding of the belowground subsystem in forest biomes worldwide, and to provide clear rationale for soil sampling to specific depths.
Keywords: forest soil physical and chemical properties, soil depths, topsoil, subsoil, forest biomes, belowground processes
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