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Tundra and boreal ecosystems encompass the northern circumpolar permafrost region and are experiencing rapid environmental change with important implications for the global carbon (C) budget. We analysed multi-decadal time series containing 302 annual estimates of carbon dioxide (CO2) flux across 70 permafrost and non permafrost ecosystems, and 672 estimates of summer CO2 flux across 181 ecosystems. We find an increase in the annual CO2 sink across non-permafrost ecosystems but not permafrost ecosystems, despite similar increases in summer uptake. Thus, recent non-growing-season CO2 losses have substantially impacted the CO2 balance of permafrost ecosystems. Furthermore, analysis of interannual variability reveals warmer summers amplify the C cycle (increase productivity and respiration) at putatively nitrogen-limited sites and at sites less reliant on summer precipitation for water use. Our findings suggest that water and nutrient availability will be important predictors of the C-cycle response of these ecosystems to future warming.
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Increasing soil respiration in a northern hardwood forest indicates symptoms of a changing carbon cycle
Soil carbon dioxide (CO2) flux, or soil respiration, is a critical control on net ecosystem carbon (C) balance. Using long-term (2002-2020) measurements at the Hubbard Brook Experimental Forest (New Hampshire, U.S.), we show that soil respiration rates have notably increased since ~2015. In 2020, cumulative summer respiration flux was approximately 90% higher than the average summer flux over the 2002–2015 period. The increase in soil respiration cannot be explained directly by temperature or pH change alone. We also found that heterotrophic microbial C mineralization and microbial biomass C have also increased rapidly since ~2015, pointing towards an increase in the bioavailability of organic C substrates. We suggest that these observations are consistent with a hypothetical increase in plant allocation of C belowground in response to changing climatic and soil conditions. Quantification of interactions among co-occurring global change factors (e.g., warming temperatures, increasing atmospheric CO2, and nutrient limitation) is needed to predict how the soil C reservoir will continue to respond to global environmental changes.
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- PAR ID:
- 10636409
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- Communications Earth & Environment
- Volume:
- 6
- Issue:
- 1
- ISSN:
- 2662-4435
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1038/s43247-025-02405-y
