Real-time monitoring of dead wood moisture in forests: Lessons learned from an intensive case study

Attributes of dead wood in forests, such as quantity, landscape position, and state of decay influence numerous ecosystem processes such as wildfire behavior, tree regeneration, and nutrient cycling. Attributes of dead wood that vary over sub-diurnal time steps, such as moisture, have not been routinely measured despite the profound effects they have on ecosystem processes. As a means to improve our understanding of forest dead wood sub-diurnal moisture dynamics, we installed an intensive Time Domain Reflectometry (TDR) sensor network in a log and surrounding soil within a northern hardwood forest, New England, USA. Intensive monitoring during a partial growing season indicated that dead wood moisture was dynamic but similar to that of surrounding soils at 15-minute intervals especially during wetting and drying events. Field results and bench analysis of the sample log revealed numerous challenges when attempting to monitor dead wood moisture with a TDR such as heterogeneous and/or advanced decay confounding TDR moisture measurements in logs. An efficient, high-frequency TDR sensor network was demonstrated to record dead wood and soil moisture fluctuations, which provides an opportunity to refine our understanding of dead wood dynamics in the context of global change such as changing precipitation regimes.