Frontiers in root ecology: recent advances and future challenges

Roots play a pivotal role in defining plant ecological success and mediating terrestrial ecosystem functioning. However, roots are difficult to study as they are hidden in the soil matrix and express a plurality of forms and functions: nutrient acquisition, anchorage, nutrient and water transport. In this special issue, we gather 20 articles from emerging topics in root ecology. We specifically focus on five frontiers that are essential to better capture plant, soil and ecosystem processes: (1) root structure and soil resource acquisition; (2) root dynamics; (3) root-root interactions; (4) root-microbe interactions and (5) the effects of roots on soil properties. For each of these sections we provide an overview of our current knowledge, highlight the contributions of this special issue, and pinpoint key remaining challenges for future work. Root resource acquisition, root dynamics, root-root and root-microbes interaction and the relative importance of root vs. soil properties on soil aggregation were shown to vary among biomes, soil and climate conditions. Such variability gives a complex but realistic picture of root functioning in real ecosystems and lays an important foundation for future work identify broad patterns of root functioning.