ABSTRACT
There has been an exponential increase in research publications addressing the impact of earthworms on terrestrial nutrient cycling processes. This research has demonstrated that earthworms significantly affect key soil properties and processes such as microbial biomass and activity, organic matter dynamics, nutrient availability, plant uptake and production, and soil structure. There is sufficient evidence to conclude that earthworms are central to regulating nutrient cycling processes in many ecosystems. Earthworms may alter the balance between conservation and loss of nutrients in ecosystems, and their net influence at large scales defines their role in ecosystem processes. Many investigations have focused on small-scale phenomena, such as nutrient dynamics 162in earthworm casts and burrows, that are critical to a mechanistic understanding of earthworm effects but are difficult to extrapolate to the ecosystem scale. In addition to the challenge of integrating information and analysis across spatial scales, there is the challenge of extrapolating the short-term effects of earthworms through time, which, as Darwin (1881) noted more than a century ago, can lead to cumulative changes at the landscape scale.
