Montane forest root growth and soil organic layer depth as potential factors stabilizing Cenozoic global change

Abstract

AbstractTree roots and their symbiotic fungal partners are believed to play a major role in regulating long‐term global climate, but feedbacks between global temperature and biotic weathering have not yet been explored in detail. In situ field data from a 3000 m altitudinal transect in Peru show fine root growth decreases and organic layer depth increases with the cooler temperatures that prevail at increased altitude. We hypothesize that this observation suggests a negative feedback: as global temperatures rise, the soil organic layer will shrink, and more roots will grow in the mineral layer, thereby accelerating weathering and reducing atmospheric CO2. We examine this mechanism with a process‐based biological weathering model and demonstrate that this negative feedback could have contributed to moderating long‐term global Cenozoic climate during major Cenozoic CO2 changes linked to volcanic degassing and tectonic uplift events.