General reversal of N- decomposition relationship during long- term decomposition in boreal and temperate forests

• 成果类型: Article
• 署名作者: Sun, Tao; Dong, Lili; Zhang, Yunyu; Hattenschwiler, Stephan; Schlesinger, William H.; Zhu, Jiaojun; Berg, Bjorn; Adair, E. Carol; Fang, Yunting; Hobble, Sarah E.
• 署名单位: Chinese Academy of Sciences; Shenyang Institute of Applied Ecology, CAS; Shenyang Agricultural University; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; Universite PSL; Ecole Pratique des Hautes Etudes (EPHE); Institut Agro; Montpellier SupAgro; CIRAD; Centre National de la Recherche Scientifique (CNRS); Institut de Recherche pour le Developpement (IRD); Universite Paul-Valery; Universite de Montpellier; Duke University; University of Helsinki; University of Vermont; University of Minnesota System; University of Minnesota Twin Cities
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8624
• DOI: 10.1073/pnas.2401398121
• 发表日期: 2024-05-14
• 关键词: leaf-litter decomposition; soil organic-matter; terrestrial ecosystems; microbial community; nitrogen limitation; amino-sugars; patterns; DYNAMICS; climate; MODEL

摘要

Decomposition of dead organic matter is fundamental to carbon (C) and nutrient cycling in terrestrial ecosystems, influencing C fluxes from the biosphere to the atmosphere. Theory predicts and evidence strongly supports that the availability of nitrogen (N) limits litter decomposition. Positive relationships between substrate N concentrations and decomposition have been embedded into ecosystem models. This decomposition paradigm, however, relies on data mostly from short - term studies analyzing controls on early - stage decomposition. We present evidence from three independent long - term decomposition investigations demonstrating that the positive N - decomposition relationship is reversed and becomes negative during later stages of decomposition. First, in a 10 - y decomposition experiment across 62 woody species in a temperate forest, leaf litter with higher N concentrations exhibited faster initial decomposition rates but ended up a larger recalcitrant fraction decomposing at a near - zero rate. Second, in a 5 - y N - enrichment experiment of two tree species, leaves with experimentally enriched N concentrations had faster decomposition initial rates but ultimately accumulated large slowly decomposing fractions. Measures of amino sugars on harvested litter in two experiments indicated that greater accumulation of microbial residues in N - rich substrates likely contributed to larger slowly decomposing fractions. Finally, a database of 437 measurements from 120 species in 45 boreal and temperate forest sites confirmed that higher N concentrations were associated with a larger slowly decomposing fraction. These results challenge the current treatment of interactions between N and decomposition in many ecosystems and Earth system models and suggest that even the best - supported short - term controls of biogeochemical processes might not predict long - term controls.