Abstract Assessing the impact of increasing carbon dioxide (CO2) on nutrient cycling requires understanding of the relationship between the concentration of CO2 and litter dynamics. It is, therefore necessary to understand leaf litter traits in response to increased atmospheric CO2. Variations in plant litter chemistry under elevated carbon dioxide (e−CO2) are the critical factors in ecosystem feedback. Litter fall, litter substrate quality, nutrient flux and decay rate in two tropical tree of Tectona grandis (Teak) and Butea monosperma (Butea) were examined. Saplings were exposed to elevated CO2 treatment (e−CO2 -550 ppm) and ambient CO2 (a−CO2; - 395 ppm) in the FACE (Free air CO2 enrichment) facility in CSIR- National Botanical Research Institute in Indo-Gangetic plain region. Litter was analysed for concentrations of carbon (C), nitrogen (N), soluble sugars (SS), lipids, lignin, cellulose, hemi-cellulose (HC) and C-based defensive compounds; soluble phenolics (SP). Nutrient concentration in naturally senesced litter for Butea and Teak was significantly different in elevated and ambient rings. Elevated CO2 significantly increased C/N (+8.27 % and +21.94 %), lowered mean litter N concentration (–3.27 % and -12.15 %), and affected the concentrations of soluble sugars, soluble phenolic and lipids in leaf litter of Butea and Teak plantations, respectively. Increase in litter biomass production (+19.75 % and 22.84 %) for both the plants under e−CO2, resulted in significant increase in the flux of N, SS, SP and lipid in to the soil. Elevated CO2 increased cellulose (+18.21 %; 12.30 %), hemicellulose (+8.48 %; +10.18 %) and lignin inputs to soils (+35.22; +43.36 %) in Butea and Teak plantation respectively. The study indicated that changes in litter biomass production and litter substrate quality during exposure to e−CO2 could significantly alter the input of nitrogen, soluble phenolic, soluble sugars, lipids, cellulose, and lignin to soils, and so also the biogeochemical cycle of the prevailing ecosystem.

中文翻译：

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二氧化碳浓度升高对自由空气富碳设施中两种亚热带物种凋落物功能性状、质量损失和养分释放的影响

摘要 评估二氧化碳 (CO2) 增加对养分循环的影响需要了解 CO2 浓度与凋落物动态之间的关系。因此，有必要了解对大气 CO2 增加做出反应的落叶性状。在二氧化碳（e-CO2）升高的情况下植物凋落物化学的变化是生态系统反馈的关键因素。检测了两种热带树 Tectona grandis (Teak) 和 Butea monosperma (Butea) 的凋落物、凋落物基质质量、养分通量和腐烂率。在印度-恒河平原地区 CSIR 国家植物研究所的 FACE（自由空气二氧化碳富集）设施中，树苗暴露于升高的二氧化碳处理（e-CO2 -550 ppm）和环境二氧化碳（a-CO2；- 395 ppm） . 分析了垃圾的碳 (C)、氮 (N)、可溶性糖 (SS)、脂质、木质素、纤维素、半纤维素 (HC) 和基于 C 的防御性化合物；可溶性酚类物质 (SP)。Butea 和柚木的自然衰老垫料中的营养浓度在升高和环境环中显着不同。CO2 升高显着增加了 C/N（+8.27 % 和 +21.94 %），降低了平均凋落物 N 浓度（–3.27 % 和 -12.15 %），并影响了 Butea 和柚木种植园，分别。在 e-CO2 下，两种植物的凋落物生物量产量增加（+19.75% 和 22.84%），导致 N、SS、SP 和脂质进入土壤的通量显着增加。二氧化碳浓度升高增加了纤维素（+18.21 %；12.30 %）、半纤维素（+8.48 %；+10.18 %）和木质素输入到土壤中（+35.22；+43。36 %) 分别在 Butea 和柚木种植园。研究表明，暴露于 e-CO2 期间凋落物生物量产生和凋落物基质质量的变化可以显着改变氮、可溶性酚类、可溶性糖、脂质、纤维素和木质素向土壤的输入，以及土壤的生物地球化学循环。盛行的生态系统。