Evenness of soil organic carbon chemical components changes with tree species richness, composition and functional diversity across forests in China

Abstract

Higher tree species richness generally increases the storage of soil organic carbon (SOC). However, less attention is paid to the influence of varied tree species composition on SOC storage. Recently, the perspectives for the stronger persistence of SOC caused by the higher molecular diversity of organic compounds were proposed.Therefore, the influences of tree species richness and composition on the molecular diversity of SOC need to be explored. In this study, an index of the evenness of diverse SOC chemical components was proposed to represent the potential resistance of SOC to decomposition under disturbances. Six natural forest types were selected encompassing a diversity gradient, ranging from cold temperate to tropical forests.We examined the correlations of tree species richness, composition, and functional diversity, with the evenness of SOC chemical components at a molecular level by 13 C nuclear magnetic resonance. Across the range, tree species richness correlated to the evenness of SOC chemical components through tree species composition. The negative correlation of evenness of SOC chemical components with tree species composition, and the positive correlation of evenness of SOC chemical components with tree functional diversity were found. These indicate the larger difference in tree species composition and the lower community functional diversity resulted in the higher heterogeneity of SOC chemical components among the communities. The positive correlation of the evenness of SOC chemical components with the important value of indicator tree species, further revealed the specific tree species contributing to the higher evenness of SOC chemical components in each forest type. Soil fungal and bacterial α-diversity had effect on the evenness of SOC chemical components. These findings suggest that the indicator tree species conservation might be preferrable to simply increasing tree species richness, for enhancing the potential resistance of SOC to decomposition. K E Y W O R D S13 C nuclear magnetic resonance, chemical component of SOC, soil microbial diversity, tree species composition, tree species diversity, tree species functional diversity | 2853 WANG et al. | INTRODUC TI ONOrganic carbon has complex chemical compounds in soils (Crow, Lajtha, Filley, et al., 2009), and is crucial to soil functioning. Litter residues derived from plants contribute many soil organic carbon (SOC) chemical compounds (Miltner et al., 2012). Some chemical components, for example, lignin, are solely derived from plant residues, while some particular products are transformed through the fungal and bacterial communities in soil, such as amino sugars (Kögel-Knabner, 2002). The relative abundance of SOC chemical compounds strongly affect its chemical reactivity and stability . Alkyl C components such as lipids, always store in soil, hence contributing to cumulatively recalcitrant C stock . Aromatic C fractions derived from lignin become extremely resistant during plant residues decomposition (Berg & Meentemeyer, 2002). Howeve...

Stand structure is more important for forest productivity stability than tree, understory plant and soil biota species diversity

“…We then considered various alternative reduced models that shared the same causal structure as the initial model and were constructed by eliminating non-significant variables one at a time. The decision to remove a path was based on the performance of the overall model fit and the p-value for the path (p > 0.05) (Wang et al, 2023). The models were evaluated according to the following two criteria: (1) pathway significance (p < 0.05) and satisfactory fit (p > 0.05) and (2) the goodness of fit of the model (chi-square test (χ 2 ) (p > 0.05) and 0 ≤ Fisher's C/df ≤ 2).…”

Effect of Land Use Change on Molecular Composition and Concentration of Organic Matter in an Oxisol

“…19,20 This implies that the chemical composition of SOM may not change, or all OM components may change simultaneously under the land use change, resulting in their relative abundance remaining unchanged. 21 The chemical characterization of OM composition has been recently advanced through the use of electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR-MS). 22,23 The technique, with its ultrahigh resolution capabilities, can identify OM compounds with precise molecular formulas.…”

“…These labile OM fractions are more vulnerable to change when exposed to altered environmental conditions including land use change. However, due to the similar processes involved in the SOM formation, the chemical composition of SOM may tend to converge, even with the diversity of OM sources. , This implies that the chemical composition of SOM may not change, or all OM components may change simultaneously under the land use change, resulting in their relative abundance remaining unchanged …”

“… 19 , 20 This implies that the chemical composition of SOM may not change, or all OM components may change simultaneously under the land use change, resulting in their relative abundance remaining unchanged. 21 …”

Environmental controls on density‐based soil organic carbon fractionations in global terrestrial ecosystems

“…Vegetation affects SOC fractions by modification of soil microbial community composition through differential quantity and quality of organic matter inputs and by altering the micro‐environment and soil characteristics (Quideau et al, 2001; Stockmann et al, 2013; Wang et al, 2023; You et al, 2014; Zhang et al, 2023). Especially, different plant species could strongly regulate SOC aggregation formation by affecting hypha and root hair (Gao et al, 2022; Gupta & Germida, 2015).…”