Chronic prescribed burning alters nutrient deposition and sediment stoichiometry in a lake ecosystem.

Prescribed fire is a common management practice for forests and other terrestrial environments. Following a prescribed burn, ash erodes into aquatic environments potentially altering terrestrial-aquatic connectivity and water quality. In this study, we collected a sediment core from Ocean Pond, FL, USA, a lake that has received fire ash from decades of prescribed burning events. Paleolimnological measurements of macrocharcoal, nutrients, stable isotopes (δ13C, δ15N), and photosynthetic pigments were used to reconstruct fire regimes, material inputs, and lake primary producer responses for periods of prescribed burns and other lake periods throughout the last 8000 years [corrected]. Results show that the period of repeated modern-prescribed fires coincided with decreased C and N depositions in the lake, while P deposition increased causing alterations to nutrient storage and stoichiometry. However, photosynthetic pigments indicated low primary producer abundance during the prescribed fire period. These changes in nutrient dynamics could provide new insights into biogeochemical pathways in land-water connected systems where burning has not been considered.