Biogeochemical legacies of a century of Eastern US reforestation
Abstract
The land cover of the Eastern United States has experienced a remarkable history of disturbance and recovery over the past two centuries. Before European settlement, forests occupied most of the land area. From the mid-19th to early 20th century, harvesting for timber and to clear agricultural land reduced forest cover by more than 90% in many places. Throughout most of the rest of the 20th century, forest cover subsequently increased following the abandonment of marginal agricultural fields and active New Deal reforestation efforts. Due to the influence of multiple anthropogenic and natural forcings, the species composition of these secondary forests has been substantially altered during this period of regrowth. In this talk, a new perspective on the biogeochemical and eco-climatic legacies of this widespread regional reforestation is presented. Specifically, AmeriFlux tower observations are used to evaluate the carbon cycle consequences of secondary succession, showing that even maturing Eastern US forests continue to function as carbon sinks. Remote-sensing and ground-based observations are combined to evaluate the impacts of succession on water and energy fluxes, showing that reforested areas offer a substantial local surface and air temperature cooling benefit when compared to nearby grasslands and croplands. Finally, data from multiple scales are used to examine ongoing species composition change and key biogeochemical processes, including mycorrhizal interactions and N deposition. Overall, the results suggest that early 20th century reforestation efforts yielded substantial, albeit unintended, climate mitigation benefits. Whether this benefit persists into the future is closely linked to ongoing species composition shifts and related biogeochemical processes.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B24C..04N
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0793 Biogeochemistry;
- CRYOSPHERE;
- 1631 Land/atmosphere interactions;
- GLOBAL CHANGE;
- 1813 Eco-hydrology;
- HYDROLOGY