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Monitoring forest carbon storage is necessary in accurately modelling the global carbon cycle. In the Northeast, terrestrial forests represent a major carbon sink with above-ground biomass (AGB) accounting for 40% of stored forest carbon. Therefore, understanding how AGB varies spatiotemporally is essential in predicting future carbon storage. Repeated measurements in permanent, long-term plots provide an opportunity to examine how carbon stored in AGB is changing over time. I used 29 years of data from the Harvard Forest Environmental Monitoring Systems (HF EMS) Site to determine how stand composition, intrinsic factors, and extrinsic environmental factors influenced rates of carbon storage in AGB over time. Using a partition around medoids (PAM) clustering method, I separated the 34 ground plots at the EMS stand into their respective stand types. I found that each stand type at the HF EMS plots accumulates carbon at consistent rates throughout the study period, although rates of carbon accumulation between stands were significantly different. Red Pine stands experience a rapid decline in biomass in 2018 due to the introduction of the Southern Pine Beetle. Across all stand types, sporadic mortality events determine variations in yearly rates of carbon accumulation, although this has little significant influence on total AGB accumulation. Leaf area index (LAI) and foliar N contents have no effect on growth increments. Extrinsic environmental variables had mixed effects on growth and mortality, highlighting the complexities of predicting forest carbon storage under changing climate conditions.
Available for download on Thursday, May 16, 2024