Institute for Multidisciplinary Applied Biology (IMAB), Departamento de Ciencias, Universidad Pública de Navarra (UPNA), 31006 Pamplona, Spain.
Institute of Innovation and Sustainable Food Chain (IS-FOOD), Departamento de Agronomía, Biotecnología y Alimentación, Universidad Pública de Navarra (UPNA), 31006 Pamplona, Spain.
Sci Total Environ. 2023 Aug 25;888:164118. doi: 10.1016/j.scitotenv.2023.164118. Epub 2023 May 13.
Soils store an important amount of carbon (C), mostly in the form of organic matter in different decomposing stages. Hence, understanding the factors that rule the rates at which decomposed organic matter is incorporated into the soil is paramount to better understand how C stocks will vary under changing atmospheric and land use conditions. We studied the interactions between vegetation cover, climate and soil factors using the Tea Bag Index in 16 different ecosystems (eight forests, eight grasslands) along two contrasting gradients in the Spanish province of Navarre (SW Europe). Such arrangement encompassed a range of four climate types, elevations from 80 to 1420 m.a.s.l., and precipitation (P) from 427 to 1881 mm year. After incubating tea bags during the spring of 2017, we identified strong interactions between vegetation cover type, soil C/N and precipitation affecting decomposition rates and stabilization factors. In both forests and grasslands, increasing precipitation increased decomposition rates (k) but also the litter stabilization factor (S). In forests, however, increasing the soil C/N ratio raised decomposition rates and the litter stabilization factor, while in grasslands higher C/N ratios caused the opposite effects. In addition, soil pH and N also affected decomposition rates positively, but for these factors no differences between ecosystem types were found. Our results demonstrate that soil C flows are altered by complex site-dependent and site-independent environmental factors, and that increased ecosystem lignification will significantly change C flows, likely increasing decomposition rates in the short term but also increasing the inhibiting factors that stabilize labile litter compounds.
土壤储存了大量的碳（C），主要以不同分解阶段的有机物形式存在。因此，了解控制分解有机物进入土壤速率的因素对于更好地理解在气候变化和土地利用变化条件下 C 储量将如何变化至关重要。我们使用茶包指数（Tea Bag Index）在西班牙纳瓦拉省（欧洲西南部）的两个对比梯度上的 16 个不同生态系统（8 个森林，8 个草原）中研究了植被覆盖、气候和土壤因素之间的相互作用。这种安排涵盖了四个气候类型、海拔 80 至 1420 米和降水量（P）从 427 至 1881 毫米/年的范围。在 2017 年春季对茶包进行培养后，我们发现植被覆盖类型、土壤 C/N 和降水量之间存在强烈的相互作用，这些因素影响了分解速率和稳定化因子。在森林和草原中，降水量的增加都提高了分解速率（k）和凋落物稳定化因子（S）。然而，在森林中，增加土壤 C/N 比提高了分解速率和凋落物稳定化因子，而在草原中，较高的 C/N 比则产生了相反的效果。此外，土壤 pH 值和 N 也对分解速率产生了积极的影响，但对于这些因素，生态系统类型之间没有差异。我们的研究结果表明，土壤 C 流动受到复杂的、依赖于地点和不依赖于地点的环境因素的影响，增加生态系统木质化将显著改变 C 流动，可能在短期内增加分解速率，但也会增加稳定不稳定凋落物化合物的抑制因子。
