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Whether the terrestrial biosphere will continue to act as a net carbon (C) sink in the face of multiple global changes is questionable. A key uncertainty is whether increases in plant C fixation under elevated carbon dioxide (CO2) will translate into decades-long C storage and whether this depends on other concurrently changing factors. We investigated how manipulations of CO2, soil nitrogen (N) supply, and plant species richness influenced total ecosystem (plant + soil to 60 cm) C storage over 19 y in a free-air CO2enrichment grassland experiment (BioCON) in Minnesota. On average, after 19 y of treatments, increasing species richness from 1 to 4, 9, or 16 enhanced total ecosystem C storage by 22 to 32%, whereas N addition of 4 g N m−2⋅ y−1and elevated CO2of +180 ppm had only modest effects (increasing C stores by less than 5%). While all treatments increased net primary productivity, only increasing species richness enhanced net primary productivity sufficiently to more than offset enhanced C losses and substantially increase ecosystem C pools. Effects of the three global change treatments were generally additive, and we did not observe any interactions between CO2and N. Overall, our results call into question whether elevated CO2will increase the soil C sink in grassland ecosystems, helping to slow climate change, and suggest that losses of biodiversity may influence C storage as much as or more than increasing CO2or high rates of N deposition in perennial grassland systems.
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This content will become publicly available on August 1, 2026
Elevated CO2 and N Gradually Weaken the Influence of Diversity on Ecosystem Stability
ABSTRACT Biodiversity promotes ecosystem productivity and stability, positive impacts that often strengthen over time. But ongoing global changes such as rising atmospheric carbon dioxide (CO2) levels and anthropogenic nitrogen (N) deposition may modulate the impact of biodiversity on ecosystem productivity and stability over time. Using a quarter‐century grassland biodiversity‐global change experiment we show that diversity increasingly enhanced productivity over time irrespective of global change treatments. In contrast, the positive influence of diversity on ecosystem stability strengthened over time under ambient conditions but weakened to varying degrees under global change treatments, largely driven by a greater reduction in species asynchrony under global changes. Thus, over 25 years, CO2and N enrichment gradually eroded some of the positive effects of biodiversity on ecosystem stability. As elevated CO2, N eutrophication, and biodiversity loss increasingly co‐occur in grasslands globally, our results raise concerns about their potential joint detrimental effects on long‐term grassland stability.
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- Award ID(s):
- 2021898
- PAR ID:
- 10632450
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Ecology Letters
- Volume:
- 28
- Issue:
- 8
- ISSN:
- 1461-023X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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