Fluxbots: A Method for Building, Deploying, Collecting and Analyzing Data From an Array of Inexpensive, Autonomous Soil Carbon Flux Chambers.

Soil carbon flux rates are a crucial metric of carbon cycling that contribute to calculating an ecosystem's carbon budget, and thus whether it is a source or sink of atmospheric carbon dioxide. However, soil carbon flux datasets are frequently low‐resolution across either space or time, limiting our abilities to identify small‐scale ecological contexts that influence soil carbon dynamics. Existing datasets are distributed unevenly, with some soil carbon‐rich regions (like tropical grasslands) significantly understudied. We developed an autonomous, inexpensive, do‐it‐yourself (DIY) soil carbon flux chamber (a "fluxbot") and data processing software. We deployed a distributed array of 12 fluxbots in a long‐term experiment in a central Kenyan savanna where it has been logistically impossible to collect high‐resolution soil carbon flux data. With this array we collected over 10,000 individual flux estimates over almost two months, spanning the end of a dry season and the start of a wet season. With our successful deployment in situ, we demonstrate the potential for low‐cost, autonomous, DIY sensors in improving resolution of soil carbon flux datasets (particularly in under‐studied or logistically challenging systems). If implemented widely, such an improvement in data collection capacities could improve our understanding of ecological and climatic drivers of soil carbon flux dynamics on the local to global scale. Plain Language Summary: Soil carbon flux, the rate at which carbon dioxide is exchanged between soil and the atmosphere, is a key feature of an ecosystem's carbon budget. However, measuring soil carbon flux rates at spatial and temporal scales that capture global ecosystems' ecological heterogeneity is extremely difficult due to the logistical constraints of manual data collection and high costs of commercial sensor systems. As such, many existing soil carbon flux datasets do not have the resolution necessary to identify small‐scale ecological patterns in carbon dynamics, and datasets are distributed unevenly across easy‐to‐monitor ecosystems globally. We developed an inexpensive, robotic, autonomous soil carbon flux chamber that collects hourly data for as long as it is deployed. We built and deployed an array of 12 sensors in an ecologically complex central Kenyan savanna ecosystem. We collected almost two months of hourly data consisting of over 10,000 soil carbon flux measurements, the largest and most high‐resolution dataset collected in this system. Wider adoption of such open‐access chambers could result in the collection of highly resolved soil carbon flux datasets in understudied systems worldwide, and greater understanding of the ecological contexts that mediate soil carbon flux. Key Points: We developed an autonomous soil carbon flux chamber ("fluxbot") to improve data collection resolution and extentWe prioritized low price and accessibility to enable the capture of small‐scale ecological heterogeneityWe distributed a fluxbot array in a large community ecology experiment to test their ability to capture complexity [ABSTRACT FROM AUTHOR]