Nitrogen and Phosphorus Release from Mixed Litter Layers is Lower than Predicted from Single Species Decay |
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Authors: | Becky A Ball Mark A Bradford Mark D Hunter |
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Institution: | (1) Environmental Studies Program, Dartmouth College, 6182 Steele Hall, Hanover, New Hampshire 03755, USA;(2) Odum School of Ecology, University of Georgia, Athens, Georgia 30602, USA;(3) School of Natural Resources and Environment and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA |
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Abstract: | Ecosystem-level nutrient dynamics during decomposition are often estimated from litter monocultures. If species effects are
additive, we can statistically predict nutrient dynamics in multi-species systems from monoculture work, and potential consequences
of species loss. However, if species effects are dependent on interactions with other litter species (that is, non-additive),
predictions based on monoculture data will likely be inaccurate. We conducted a 3-year, full-factorial, mixed-litter decomposition
study of four dominant tree species in a temperate forest and measured nitrogen and phosphorus dynamics to explore whether
nutrient dynamics in mixtures were additive or non-additive. Following common approaches, we used litterfall data to predict
nutrient dynamics at the ecosystem-level. In mixtures, we observed non-additive effects of litter mixing on nutrient dynamics:
the presence of nutrient-rich species in mixture facilitated nutrient release, whereas nutrient-poor species facilitated nutrient
retention. Fewer nutrients were released from mixtures containing high-quality litter, and more immobilized from mixtures
containing low-quality litter, than predicted from monocultures, creating a difference in overall nutrient release between
predicted and actual dynamics in litter mixtures. Nutrient release at the ecosystem-level was greatly overestimated when based
on monocultures because the effect of species interactions on nutrient immobilization was not accounted for. Our data illustrate
that the identity of species in mixtures is key to their role in non-additive interactions, with repercussions for mineral
nutrient availability and storage. These results suggest that predictions of ecosystem-level nutrient dynamics using litter
monoculture data likely do not accurately represent actual dynamics because the effects of litter species interactions are
not incorporated.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | ecosystem function decomposition nutrient dynamics litter nitrogen litter phosphorus litter mixtures species diversity species composition species loss biodiversity |
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