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Title: Sensitivity of grassland carbon pools to plant diversity, elevated CO 2 , and soil nitrogen addition over 19 years
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 (CO 2 ) will translate into decades-long C storage and whether this depends on other concurrently changing factors. We investigated how manipulations of CO 2 , 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 CO 2 enrichment 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 −1 and elevated CO 2 of +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 CO 2 and N. Overall, our results call into question whether elevated CO 2 will 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 CO 2 or high rates of N deposition in perennial grassland systems.  more » « less
Award ID(s):
1753859 2021898 1831944
PAR ID:
10227370
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Proceedings of the National Academy of Sciences
Volume:
118
Issue:
17
ISSN:
0027-8424
Page Range / eLocation ID:
e2016965118
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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