实验增温对陆地生态系统根系生物量的影响

根系是植物吸收土壤水分和养分的重要器官, 驱动着多个生态系统过程, 该研究揭示了实验增温对根系生物量的影响及机制, 可为气候变暖背景下土壤碳动态和生态系统过程的变化提供理论依据。该研究从已发表的151篇国内外研究论文中收集到611组数据, 通过整合分析(meta-analysis)方法研究了实验增温对根系生物量(根系总生物量、粗根生物量、细根生物量、根冠比)的影响, 并探讨了增温幅度、增温年限、增温方式的影响, 以及根系生物量对增温的响应与本底环境条件(生态系统类型、年平均气温、年降水量、干旱指数)的关系。结果表明: (1)模拟增温使细根生物量显著增加8.87%, 而对根系总生物量、粗根生物量、根冠比没有显著影响; (2)中等强度增温(1-2 ℃)使得细根生物量和根冠比分别提高14.57%和23.63%; 中短期增温实验(<5年)对细根生物量具有促进影响, 而长期增温实验(≥5年)使细根生物量有降低的趋势; 开顶箱增温和红外辐射增温分别使细根生物量显著提高了17.50%和12.16%, 而电缆加热增温使细根生物量和粗根生物量显著降低了23.44%和43.23%; (3)不同生态系统类型对于增温响应不一致, 模拟增温使苔原生态系统细根生物量显著提高了21.03%, 细根生物量对增温的响应与本底年平均气温、年降水量、干旱指数均呈显著负相关关系。

Effects of experimental warming on root biomass in terrestrial ecosystems

Aims Roots are an important organ for plants to absorb soil water and nutrients and can drive multiple ecosystem processes. This study disentangles the effects and underlying mechanisms of experimental warming on root biomass in terrestrial ecosystems, aiming to better understand soil carbon dynamics and inform the changes in ecosystem processes under climate warming. Methods In this study we compiled data on 611 paired observations from 151 published peer-reviewed articles, and analyzed the responses of several plant root biomass variables, including total root biomass, fine root biomass, coarse root biomass, and root:shoot ratio, to warming using meta-analysis. The responses of root biomass to the magnitude, duration and method of warming treatments, and the warming responses of root biomass in relation to background environmental conditions (i.e. ecosystem types, mean annual air temperature, mean annual precipitation, and aridity index) were examined. Important findings Simulated warming significantly increased fine root biomass by 8.87%, but had no significant effects on total root biomass, coarse root biomass, and root:shoot ratio. Moderate magnitude of warming (1-2 °C) significantly increased fine root biomass and root:shoot ratio by 14.57% and 23.63%, respectively. While the short- to medium-term (<5 years) warming enhanced fine root biomass, a long-term warming (≥5 years) had a tendency to decrease it. Both open-top chamber and infrared radiators significantly increased fine root biomass by 17.50% and 12.16%, respectively; whilst heating cables significantly decreased fine root biomass by 23.44% and coarse root biomass by 43.23%. The warming responses of root biomass were inconsistent across different ecosystem types. Notably, warming significantly increased fine root biomass by 21.03% in tundra ecosystems. The response of fine root biomass to simulated warming had significant and negative correlations with the background mean annual air temperature, mean annual precipitation, and aridity index.