Soil fauna and their potential responses to warmer soils
Most people who concern themselves with the study of soil will broadly agree that soil is a dynamic mixture of chemical, physical, and biological components. That there is a biological component to soil therefore suggests that soil, or at least “healthy” soil, is alive. But to say that soil is simply alive does not do justice to the multitude of organisms that occupy soil, ranging from the simplest forms, like bacteria, through most of the invertebrate phyla, and up to fossorial reptilian and mammalian vertebrates. In recent years, life in soil has been intensively studied mainly in terms of microbial organisms (archaea, bacteria, and fungi), with less emphasis on invertebrate animals (see Coyle et al., 2017). However, invertebrates are diverse and abundant in soils world-wide, and they are known to influence soil microbial communities and soil processes. In relation to warming, soil invertebrates (in general) are understudied, the majority of studies focus on microarthropods (mites and Collembola). This chapter will first give an overview of soil invertebrate distributions and functions and follow with a discussion of the potential responses of these organisms to a warming soil. Due to the limited amount of research in this area, the diversity of the fauna, and the diversity of the existing studies, our discussion centers on a framework for understanding observed and potential responses and a suite of themes interwoven through the literature.