Faculty of Natural Resources Management, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada; State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 10093, China.
Faculty of Natural Resources Management, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada.
Sci Total Environ. 2024 Dec 10;955:176952. doi: 10.1016/j.scitotenv.2024.176952. Epub 2024 Oct 18.
Fine roots play crucial roles in terrestrial biogeochemical cycles. Although biodiversity loss and changes in precipitation are two major drivers of global change, our understanding of their effects on fine root biomass (FRB), root functional traits, and fine root decay (FRD) remains incomplete. We manipulated precipitation in young boreal forests dominated by Populus tremuloides, Pinus banksiana, and their relatively even mixtures using 25 % addition, ambient, and 25 % reduction in throughfall during the growing season. We collected root samples using soil core and trunk-traced methods to quantify FRB and root traits, and we simulated fine root decay using an in-situ experiment over 531 days. We found that compared to the average of single-species-dominated stands, species mixtures increased FRB by 41 % under ambient throughfall, by 89 % under throughfall reduction and by 71 % under throughfall addition. Root surface area, fine root volume, and root length density responded to species mixtures similarly to FRB. Meanwhile, species mixtures reduced FRD across all water treatments. There was a positive relationship between the effect of species mixtures on the FRD of absorptive roots and those on the FRB. Our results highlight that species mixtures could modify carbon cycling by enhancing fine root biomass accumulation and reducing its decomposition of young boreal forests under changing precipitation.
细根在陆地生物地球化学循环中起着至关重要的作用。尽管生物多样性丧失和降水变化是全球变化的两个主要驱动因素，但我们对它们对细根生物量（FRB）、根功能特性和细根分解（FRD）的影响的理解仍然不完整。我们在以颤杨、黑云杉和它们相对均匀的混合林为主的年轻北方森林中，通过在生长季节增加 25%、保持自然和减少 25%的穿透降水来操纵降水。我们使用土壤芯和树干追踪方法收集根样本，以量化 FRB 和根特性，并通过 531 天的原位实验模拟细根分解。我们发现，与单一树种为主的林分的平均值相比，在自然穿透降水下，物种混合使 FRB 增加了 41%，在穿透降水减少时增加了 89%，在穿透降水增加时增加了 71%。根表面积、细根体积和根长密度对 FRB 的响应与 FRB 相似。同时，物种混合在所有水分处理下都降低了 FRD。物种混合对吸收根 FRD 的影响与对 FRB 的影响之间存在正相关关系。我们的研究结果强调，在降水变化下，物种混合可以通过增加细根生物量积累和减少其分解来改变年轻北方森林的碳循环。
