Carbon and vegetation dynamics across two mid-latitude forest stands: means, response to climate, and decadal trends

Keywords: carbon cycle, ecosystem ecology, global change, vegetation dynamics
Abstract Type: Paper Abstract

Abstract

Vegetation in the terrestrial biosphere absorbed approximately 31% of the carbon dioxide emitted by human activities during the most recent decade (2010-2019; IPCC 2021), slowing the rate of climate change as a result. However, the magnitude of the terrestrial carbon sink in the future is uncertain, especially as the terrestrial biosphere responds to climate change.

In this study, we investigated the long-term carbon balance of two differently-aged stands in a midlatitude forest in north-central Massachusetts, USA. One forest stand (“plantation”) is a red pine plantation that was established in 1925, the other (“harvest”) is a former red pine plantation that has been undergoing natural succession since harvest in 1990. All trees ≥ 5 cm diameter breast height (DBH; 1.3 m) were identified, measured, and tagged, and have been measured yearly from 2008-2022.

There was a significant loss of aboveground woody biomass at the plantation site, from 137 Mg C ha-1 in 2008 to 102 Mg C ha-1 in 2020. This was driven by the loss of 49 Mg C ha-1 red pine; as the overlying red pine canopy has thinned, the thickening understory now sequesters ~112% more carbon than in 2008. In contrast, the harvest site has steadily sequestered carbon since 2008, with its aboveground woody biomass rising from 35 Mg C ha-1 in 2008 to 59 Mg C ha-1 in 2020. Results from this study highlight the spatial and temporal variability in forest carbon sequestration and the important role of vegetation dynamics in the terrestrial carbon sink.