Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education, School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China.
Institute of Tropical Biodiversity and Sustainable Development, University Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia.
Sci Total Environ. 2022 Jul 15;830:154702. doi: 10.1016/j.scitotenv.2022.154702. Epub 2022 Mar 24.
Ash is a fundamental component of plant litter and plays a vital role in regulating litter decomposition. However, to date, global patterns and underlying mechanisms of initial litter ash concentrations remain unclear. Here, we used 570 observations collected from 104 independent publications to assess the global patterns of initial plant litter ash concentrations and evaluated the effects of mycorrhizal association [arbuscular mycorrhiza (AM) vs. ectomycorrhiza (ECM)], taxon group (gymnosperm vs. angiosperm), life form (tree vs. shrub vs. herb), leaf type (broadleaf vs. needle), and environmental factors such as climate and soil properties on initial litter ash concentration. The results showed that (1) global average ash concentrations varied significantly among different plant tissues and were 7.3, 4.5, 3.7, 3.5, 3.1, 2.4, and 1.5% in leaf, root, bark, reproductive tissue (flower and fruit), branch, stem, and wood litter, respectively; (2) in leaf litter, the initial ash concentrations of AM plants and species associated with both AM and ECM fungi were higher than those of ECM plants, and those of the tree species were lower than those of the herbs and shrubs; in root litter, the initial ash concentrations of the AM plants were lower than those of the species associated with both AM and ECM fungi but higher than those of the ECM plants; in both leaf and root litter, the initial ash concentrations of the angiosperms and broadleaf trees were higher than those of the gymnosperms and needle trees, respectively, while the effect of plant traits on branch litter was not obvious; and (3) the initial ash concentration of leaf litter was predominantly driven by mycorrhizal association and taxon group, while that of root litter tended to be driven by mycorrhizal association well as soil organic carbon. Our study clearly assessed the global patterns and underlying mechanisms of initial plant litter ash concentrations, which could help in better understanding the role of ash in litter decomposition and the related processes of carbon and nutrient cycling.
灰分是植物凋落物的基本组成部分，在凋落物分解中起着至关重要的作用。然而，迄今为止，初始凋落物灰分浓度的全球格局和潜在机制仍不清楚。在这里，我们使用了 104 个独立出版物中的 570 个观测结果来评估初始植物凋落物灰分浓度的全球格局，并评估了菌根共生（丛枝菌根 [AM] 与外生菌根 [ECM]）、分类群（裸子植物与被子植物）、生活型（乔木、灌木与草本）、叶型（阔叶与针叶）以及气候和土壤特性等环境因素对初始凋落物灰分浓度的影响。结果表明：(1) 全球平均灰分浓度在不同植物组织之间差异显著，叶、根、树皮、生殖组织（花和果实）、枝、茎和木材凋落物的灰分浓度分别为 7.3%、4.5%、3.7%、3.5%、3.1%、2.4%和 1.5%；(2) 在叶凋落物中，AM 植物和与 AM 和 ECM 真菌共生的物种的初始灰分浓度高于 ECM 植物，而乔木的初始灰分浓度低于草本和灌木；在根凋落物中，AM 植物的初始灰分浓度低于与 AM 和 ECM 真菌共生的物种，但高于 ECM 植物；在叶和根凋落物中，被子植物和阔叶乔木的初始灰分浓度均高于裸子植物和针叶乔木，而植物性状对枝凋落物的影响不明显；(3) 叶凋落物的初始灰分浓度主要受菌根共生和分类群的驱动，而根凋落物的初始灰分浓度则主要受菌根共生和土壤有机碳的驱动。我们的研究清楚地评估了初始植物凋落物灰分浓度的全球格局和潜在机制，这有助于更好地理解灰分在凋落物分解和相关碳和养分循环过程中的作用。
