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In the Yukon-Kuskokwim (YK) Delta, geese create grazing lawns in Carex subspathacea meadows. Geese annually maintain the grazing lawns, resulting in different aboveground morphological expressions for grazed Carex subspathacea compared to ungrazed Carex subspathacea. Grazed C. subspathacea tends to grow to an average of 1.5 centimeters (cm) in height and has a floret growth form, while ungrazed C. subspathacea reaches an average height of nearly 15.5 cm. Additionally, grazed C. subspathacea has lower Carbon : Nitrogen (C:N) content than ungrazed C. subspathacea. Furthermore, both the physical alterations to Carex subspathacea and the changes to the soil physiochemical environment caused by grazing suggest that aboveground herbivory may affect root trait expression of C. subspathacea, which in turn may influence biogeochemical processes such as soil respiration and decomposition rates. This data set contains information on Carex subspathacea root traits, including root morphology (total length, surface area, and volume), root exudates (dissolved organic carbon concentration), and root chemistry (carbon, nitrogen, phosphorus, lignin, cellulose, and acid fiber detergent) collected in Western Alaska's Yukon-Kuskokwim's delta. The samples were collected from two Carex subspathacea habitat types (grazed or ungrazed).
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Herbivory in a low Arctic wetland alters intraspecific plant root traits with consequences for carbon and nitrogen cycling
Abstract High latitude wetlands are ecologically important ecosystems due to their large carbon (C) storage capacity and because they serve as breeding and nesting habitat for large populations of migratory birds. Goose herbivory in wetland meadows affects leaf chemical and morphological traits and also influences soil properties by increasing soil temperature and depositing faeces. Grazing‐induced changes to above‐ground traits and soil properties impact C cycling, but the influence of grazing on root‐mediated C and nitrogen (N) cycling has not been explored.We investigated how goose herbivory in a low‐Arctic coastal wetland in western Alaska affected root morphological, physiological and chemical traits of a dominant graminoid by assessing plant traits in ungrazed versus heavily grazed sedge meadows. We also performed a 11‐week lab‐based root incubation experiment to determine how grazing affects CO2‐C efflux, the size and decay rate of the fast‐cycling C pool (i.e. C with a mean residence time of days to weeks, determined via CO2‐C efflux), and patterns of N mineralization during root decomposition.Goose grazing altered root chemical traits by increasing root N by 7%, cellulose by 12%, and ash content by 17%, indicating that grazing shifted root chemical traits towards a resource‐acquisition strategy. Grazing did not alter root biomass, morphology or bulk C exudation. In our root incubation, soils that included the roots of grazed plants tended to exhibit greater CO2‐C efflux than those containing ungrazed plant roots due to a larger fast‐cycling C pool. Additionally, grazing‐induced increases in soil temperature led to greater CO2‐C efflux due to a faster decay rate of the fast‐cycling C pool. Finally, compared with ungrazed roots, we found that the decomposition of grazed roots resulted in more N being transferred to root necromass from the surrounding soil, suggesting that microbial communities decomposing grazed roots immobilized N.Synthesis. Overall, our results indicate that goose grazing increased C‐cycling rates by influencing soil environmental conditions and by altering the ecological strategy of grazed plants. In contrast, grazing decreased net N mineralization by promoting N immobilization. These results suggest that changing patterns and abundances of herbivores can have substantial effects on elemental cycles.
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- Award ID(s):
- 1932889
- PAR ID:
- 10580278
- Publisher / Repository:
- British Ecological Society
- Date Published:
- Journal Name:
- Journal of Ecology
- ISSN:
- 0022-0477
- 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/10.1111/1365-2745.70028
