Litter type control on soil C and N stabilization dynamics in a temperate forest |
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Authors: | Pierre‐Joseph Hatton Cristina Castanha Margaret S Torn Jeffrey A Bird |
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Institution: | 1. School of Earth & Environmental Sciences, Queens College, CUNY, New York, NY, USA;2. Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA |
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Abstract: | While plant litters are the main source of soil organic matter (SOM) in forests, the controllers and pathways to stable SOM formation remain unclear. Here, we address how litter type (13C/15N‐labeled needles vs. fine roots) and placement‐depth (O vs. A horizon) affect in situ C and N dynamics in a temperate forest soil after 5 years. Litter type rather than placement‐depth controlled soil C and N retention after 5 years in situ, with belowground fine root inputs greatly enhancing soil C (x1.4) and N (x1.2) retention compared with aboveground needles. While the proportions of added needle and fine root‐derived C and N recovered into stable SOM fractions were similar, they followed different transformation pathways into stable SOM fractions: fine root transfer was slower than for needles, but proportionally more of the remaining needle‐derived C and N was transferred into stable SOM fractions. The stoichiometry of litter‐derived C vs. N within individual SOM fractions revealed the presence at least two pools of different turnover times (per SOM fraction) and emphasized the role of N‐rich compounds for long‐term persistence. Finally, a regression approach suggested that models may underestimate soil C retention from litter with fast decomposition rates. |
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Keywords: | 13C 15N fine root forest litter litter decomposition needle soil organic matter stabilization |
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