School of Karst Science / State Engineering Technology Institute for Karst Decertification Control, Guizhou Normal University, Guiyang, 550001, China.
BMC Plant Biol. 2023 May 18;23(1):262. doi: 10.1186/s12870-023-04274-z.
Leaf litter is the products of metabolism during the growth and development of plantation, and it is also an important component of nutrient cycling in plantation ecosystems. However, leaf litter chemistry and its effects on soil microorganisms in different ages, as well as the interactions between chemical components in leaf litter have been rarely reported. Based on this, this paper took Zanthoxylum planispinum var. dintanensis (hereafter Z. planispinum) plantations of 5-7, 10-12, 20-22, and 28-32 years old as the objects. By using one-way ANOVA, Pearson correlation analysis and redundancy analysis, we investigated leaf litter chemistry and its effects on soil microorganisms in different ages, and to reveal internal correlation of various chemical components in leaf litter, which can provide a scientific basis for the regulation of soil microbial activity in plantations.
The variation of organic carbon with plantation age was more stable compared to total nitrogen and phosphorus of leaf litter. Nitrogen resorption was stronger than phosphorus resorption efficiency in Z. planispinum, and resorption efficiencies of leaf nitrogen and phosphorus for different ages were lower than the global average. Total nitrogen was highly significantly positively correlated with lignin, and total potassium was significantly positively correlated with tannin, suggesting the increase of inorganic substances in leaf litter would promote the accumulation of secondary metabolites. The leaf litter chemical traits explained up to 72% of soil microorganisms, where lignin was positively correlated with fungi and negatively correlated with bacteria, indicating that fungi are able to decompose lower quality litter and can break down complex and stable organic compounds more rapidly than bacteria. The nutrient elements carbon and nitrogen in the leaf litter and their interrelationship also have a great impact on soil microorganisms, because carbon is not only the element that provides energy, but also the element with the largest content in the microbiota.
The sustained increase in inorganic nutrients of leaf litter did not favor the decomposition of secondary metabolites, but rather inhibited the degradation of leaf litter. The significant positive effect of the leaf litter chemistry on soil microorganisms indicates the important role of leaf litter in promoting nutrient cycling in Z. planispinum plantations.
凋落物是植物生长发育过程中的代谢产物，也是人工林生态系统养分循环的重要组成部分。然而，不同林龄凋落物化学性质及其对土壤微生物的影响，以及凋落物化学组成之间的相互作用鲜有报道。基于此，本研究以 5-7 年、10-12 年、20-22 年和 28-32 年生花椒（Zanthoxylum planispinum var. dintanensis）人工林凋落物为研究对象，采用单因素方差分析、Pearson 相关性分析和冗余分析，研究了不同林龄凋落物化学性质及其对土壤微生物的影响，揭示了凋落物各化学组成之间的内在联系，可为调控人工林土壤微生物活性提供科学依据。
与凋落物全氮和全磷相比，有机碳随林龄的变化更稳定。花椒的氮素再吸收率大于磷素再吸收率，不同林龄凋落物氮、磷的再吸收率均低于全球平均值。凋落物全氮与木质素呈极显著正相关，全钾与单宁呈显著正相关，说明凋落物中无机物质的增加会促进次生代谢物的积累。凋落物化学特征解释了高达 72%的土壤微生物，其中木质素与真菌呈正相关，与细菌呈负相关，说明真菌能够分解质量较低的凋落物，并且比细菌更能快速分解复杂而稳定的有机化合物。凋落物中的养分元素碳和氮及其相互关系也对土壤微生物有很大影响，因为碳不仅是提供能量的元素，也是微生物中含量最大的元素。
凋落物中无机养分的持续增加不利于次生代谢物的分解，反而抑制了凋落物的降解。凋落物化学性质对土壤微生物的显著正效应表明，凋落物在促进花椒人工林养分循环方面发挥着重要作用。
