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Abstract AimsHerbivores create large differences in litter decomposition rates, but identifying how they do this can be difficult because they simultaneously influence both biotic and abiotic factors. In the Yukon-Kuskokwim (Y-K) River Delta in western Alaska, geese are dominant herbivores in wet-sedge meadows, where they create ‘grazing lawns’ that have nutrient-rich litter and an open habitat structure. To understand how geese affect decomposition, we tested the effects of litter quality and habitat type on litter decomposition over one year. MethodsWe performed a litter bag study in which we collected two litter types representing grazed and ungrazed vegetation conditions (high quality litter similar to grazed litter, and lower quality senesced, ungrazed litter), then incubated them in ‘grazing lawn’ and ungrazed meadows. Litter mass loss, carbon, nitrogen, cellulose and lignin content were measured after 3, 6, 9, and 52 weeks. We also monitored abiotic conditions (i.e., soil temperature, UV radiation, throughfall, and soil moisture content) in each habitat type. ResultsHigh-quality litter (lower lignin:N ratios) lost more mass than low-quality ungrazed litter over the whole study. However, at different times during the decomposition process, lower quality litter decomposed faster in grazed habitat, whereas higher quality litter decomposed faster in ungrazed habitat. This occurred despite abiotic conditions in grazed habitat that generally promote faster decomposition. ConclusionResults suggest that herbivore-induced increases in litter quality increase decomposition rates, and that the accumulation of the low-quality litter in ungrazed habitats is partly due to slow decomposition rates. While herbivores influence habitat conditions, the effects of habitat on decomposition differed across litter qualities, which suggests that other variables, such as differing microbial communities, play a role in decomposition processes. Graphical abstract
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Root Traits of Carex subspathacea in the Yukon-Kuskokwim Delta, 2022
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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- Award ID(s):
- 1932889
- PAR ID:
- 10519417
- Publisher / Repository:
- NSF Arctic Data Center
- Date Published:
- Subject(s) / Keyword(s):
- Traits Roots Herbivory Yukon-Kuskokwim
- Format(s):
- Medium: X Other: text/xml
- Location:
- Yukon-Kuskokwim Delta, Alaska
- Institution:
- Utah State University
- Sponsoring Org:
- National Science Foundation
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