Northern hardwood forests are expected to experience an increase in mean annual air temperatures, and a decrease in winter snowpack and greater frequency of soil freeze/thaw cycles (FTCs) by the end of the century. As a result of these anticipated changes, northern hardwood forests in the northeastern U.S. will also have warmer soil temperatures in the growing season and colder soils in winter. Prior studies show that warmer soils in the growing season increase net primary productivity (NPP) and C storage as a result of increased soil net N mineralization, while increases in soil freezing in winter reduces plant uptake of N and C as a result of root damage. However, the combined effects of warmer soils in the growing season and increased soil freeze/thaw cycles in winter on tree litter mass and chemistry are unknown. We report here results from the Climate Change Across Seasons Experiment (CCASE) at Hubbard Brook Experimental Forest in New Hampshire, USA to characterize the response of leaf litter mass and chemistry to growing season warming combined with soil freeze–thaw cycles in winter. Across the years 2014-2017, litterfall mass and chemistry (%C, %N, C:N) were not significantly affected by changes in soil temperature; however, there was a trend of higher total litterfall mass and litter N mass from plots where soils were warmed in the growing season, but this increase disappeared with the addition of FTCs in winter. These results indicate that while rates of NPP and the total mass of N could be increased with rising soil temperatures over the next century in northern hardwood forests, the combination of warmer soils in the growing season and colder soils in winter may ultimate have little to no impact on litter mass or chemistry. We conclude that considering the combined effects of climate changes in the growing season and in winter is vital for the accurate determination of the response of litterfall mass and chemistry in northern hardwood forests.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/42229 |
| Date | 08 March 2021 |
| Creators | Berry, Melissa |
| Contributors | Templer, Pamela |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | Attribution 4.0 International, http://creativecommons.org/licenses/by/4.0/ |
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