Abstract
Globally widespread woody encroachment into grass-dominated ecosystems has substantial consequences for carbon (C), nitrogen (N), and phosphorus (P) cycles. Despite its significance as an essential macronutrient, however, little is known regarding potential changes in the sulfur (S) cycle. We quantified S concentrations, stoichiometric relationships, and δ34S values in the plant-soil environment to investigate landscape-scale changes in the S cycle following grassland-to-woodland transitions in a subtropical savanna. Plant tissues of woody species had significantly higher S concentrations and δ34S values than those of herbaceous species, resulting in a landscape-scale correspondence between spatial patterns of S and δ34S in surface soils (0–5 cm) and vegetation distribution, with higher S and δ34S in soils beneath woody patches. These patterns were more subtle at soil depths > 5 cm. Woody plants had higher N:S ratios but comparable P:S ratios relative to herbaceous species, which contributed to contrasting spatial patterns between N:S and P:S ratios in surface soils. Sulfur in surface soils increased proportionally less relative to N, but proportionally more compared to P. Our findings indicate that grassland-to-woodland transitions amplify landscape-scale S dynamics, especially in surface soils, and create a S-enriched environment that enables woody plants to acquire sufficient S relative to demand to support their continued productivity and proliferation.
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Data availability
The dataset is available in the Dryad Digital Repository: https://doi.org/10.5061/dryad.h44j0zpkh
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Codes to interpret data and prepare the figures are available on request from the corresponding author.
Change history
21 July 2021
A Correction to this paper has been published: https://doi.org/10.1007/s10533-021-00835-2
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Acknowledgements
Yong Zhou was supported by a Sid Kyle Graduate Merit fellowship from the Department of Ecosystem Science and Management and a Tom Slick Graduate Research Fellowship from the College of Agriculture and Life Sciences, Texas A&M University. We thank Dr. X. Ben Wu for his role in experimental design, and David and Stacy McKown for on-site logistics at the La Copita Research Area.
Funding
This research was supported by a Doctoral Dissertation Improvement Grant from the U.S. National Science Foundation (DEB/DDIG1600790), by USDA/NIFA Hatch Project (1003961), and by the Sid Kyle Endowed Chair in the Department of Ecology and Conservation Biology at Texas A&M University.
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Y. Z. and T.W.B. conceived the research; Y.Z. conducted fieldwork; Y.Z. and A. H. performed sample analyses; Y. Z. and T.W.B. interpreted the data; Y.Z. wrote the first draft of the manuscript and all authors contributed substantially to revisions.
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The original version of this article was revised: the second author name was corrected to Ayumi Hyodo.
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Zhou, Y., Hyodo, A. & Boutton, T.W. Ecosystem sulfur accumulation following woody encroachment drives a more open S-cycle in a Subtropical Savanna. Biogeochemistry 155, 343–355 (2021). https://doi.org/10.1007/s10533-021-00829-0
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DOI: https://doi.org/10.1007/s10533-021-00829-0