Multi‐dimensionality as a path forward in plant‐soil feedback research

Feedback between plants and their associated soil biota is an important driver of plant distribution, abundance and community composition with consequences for ecosystem functioning. The field of plant‐soil feedback (PSF) research has become an integral subdiscipline of terrestrial ecosystem ecology, and in recent decades has rapidly evolved by deepening and broadening its scope. We review the major developments in the field, discuss methodological considerations and present a way forward for new approaches to PSF research that will lead to a more generalized and predictive understanding of PSFs. We illustrate that the field of PSF research has pursued multiple dimensions, including temporal scales, biogeographic perspectives, environmental context and the level of biological resolution. Plant‐soil feedbacks have been related to successional species turnover, but our inferences are often constrained by experimental time‐scales, and anthropogenic impacts can alter or disrupt the temporal interactions between plants and soil biota. Plant‐soil feedbacks also have been used to explain spatial patterns of plant recruitment, coexistence and diversity, and have increasingly been linked to the patterns of spread and abundance of non‐native and invasive plants. In recent years, more consideration also has been given to the sensitivity of PSF to environmental context, in particularly to gradients of resource availability and changing climatic conditions (including extreme events). Here, of particular interest are the differential responses of mutualistic and antagonistic soil biota. How plants interact with different groups of soil biota has further been predicted from species' phylogenetic relatedness and increasingly also from plant chemical and morphological shoot, root and litter traits. Synthesis. In moving the field forward, future PSF research should take a multidimensional approach by explicitly considering cross‐connections between dimensions, including, for example, spatio‐temporal variation in resource availability, and trait–environment relationships across taxonomic and functional groups of plants and soil organisms. This forward movement will be accelerated by further methodological advances utilizing new types of experiments in the laboratory and in the field, as well as establishing global collaborative networks.