San-Emeterio L M, Hidalgo-Galvez M D, de la Rosa J M, Pérez-Ramos I, González-Pérez J A
Instituto de Recursos Naturales y Agrobiología de Sevilla, Consejo Superior de Investigaciones Cientificas (IRNAS-CSIC), Av. Reina Mercedes 10, 41012 Sevilla, Spain; Department of Soil and Environment, Swedish University of Agricultural Sciences (SLU), Lenmart Hjelms Väg 9, P. O. Box 7014, 75007 Uppsala, Sweden.
University of Seville, 41012 Seville, Spain; Department of Ecology, Faculty of Sciences II, University of Alicante, 03690 San Vicente del Raspeig, Alicante, Spain.
Sci Total Environ. 2024 Oct 10;946:174317. doi: 10.1016/j.scitotenv.2024.174317. Epub 2024 Jul 1.
Lignin is an abundant and recalcitrant biopolymer of major relevance as soil organic matter (SOM) component playing a significant role in its stabilization. In this work, a factorial field experiment was established, where three climatic treatments (W, warming; D, drought; W + D, warming + drought), mimicking future climate change scenarios were installed over five years in a Mediterranean savannah "dehesa", accounting for its landscape diversity (under the tree canopy and in open grassland). A combination of analytical pyrolysis (Py-GC/MS) and the study of biogeochemical proxies based on lignin monomers is used for the direct detection of lignin-derived phenols and to infer possible shifts in lignin dynamics in soil. A total of 27 main lignin-derived methoxyphenols were identified, exhibiting different patterns and proportions, mainly driven by the effect of habitat, hence biomass inputs to SOM. An accelerated decomposition of lignin moieties -(exhibited by higher LG/LS and Al/K + Ac ratios)- is particularly exacerbated by the effect of all climatic treatments. There is also an overall effect on increasing lignin oxidation of side chain in syringyl units, especially under the tree canopy due to the alteration in biomass degradation and potential stimulation of enzyme activities. Conversely, in open grassland these effects are slower since the microbial community is expected to be already adapted to harsher conditions. Our findings suggests that climate change-related temperature and soil moisture deviations impact soil lignin decomposition in dehesas threatening this productive Mediterranean agroecosystem and affecting the mechanism of soil carbon storage.
木质素是一种含量丰富且难以降解的生物聚合物，作为土壤有机质（SOM）的组成部分具有重要意义，在其稳定性方面发挥着重要作用。在这项研究中，我们建立了一个析因田间试验，在一片地中海大草原“德埃萨”上，设置了三种模拟未来气候变化情景的气候处理（W，升温；D，干旱；W + D，升温 + 干旱），为期五年，同时考虑了其景观多样性（树冠下和开阔草地）。结合热解气相色谱/质谱联用（Py-GC/MS）分析和基于木质素单体的生物地球化学指标研究，用于直接检测木质素衍生的酚类物质，并推断土壤中木质素动态的可能变化。共鉴定出27种主要的木质素衍生甲氧基酚，呈现出不同的模式和比例，主要受栖息地影响，即生物量输入到土壤有机质的情况。木质素部分的加速分解（以较高的LG/LS和Al/K + Ac比率为表现）在所有气候处理的影响下尤其加剧。对于丁香基单元侧链的木质素氧化增加也存在总体影响，特别是在树冠下，这是由于生物量降解的改变和酶活性的潜在刺激。相反，在开阔草地，这些影响较慢，因为预计微生物群落已经适应了更恶劣的条件。我们的研究结果表明，与气候变化相关的温度和土壤湿度偏差会影响德埃萨地区土壤木质素的分解，威胁到这个高产的地中海农业生态系统，并影响土壤碳储存机制。
