Effects of afforestation on soil organic matter characteristics under subtropical forests with low elevation

Abstract

We selected sites of natural broad-leaved forests and adjacent coniferous plantations (Cunninghamia konishii and Calocedrus formosana of 30 and 80 years old, respectively) in central Taiwan to evaluate the effects of plantations on soil organic matter (SOM) characteristics and composition. SOM was characterized by chemical analyses, solid-state 13 C cross-polarization magic-angle nuclear magnetic resonance (CPMAS 13 C NMR), and optical measurements. Semiquantitative analysis of CPMAS 13 C NMR spectra showed the litter of broad-leaved forests to be less resistant to decomposition than that of coniferous forests. The humification degree of SOM was higher under broadleaved than coniferous forests because of the relatively high percentage of aromatic C and carboxyl C in the humic acids (HAs) of A horizons under broad-leaved forests. Additionally, the E 4 /E 6 ratio of HAs was lower in the A horizon under broad-leaved than coniferous forests, which reflected more condensation of SOM. High alkyl C content under coniferous forests could be attributed to needle litter quality, which has a high content of waxes or lipids. Afforestation with conifers induced accumulation of the litterfall layer, gradually increased SOM concentrations, and changed the composition structures of SOM in the topsoils.

Effect of 40 and 80 Years of Conifer Regrowth on Soil Microbial Activities and Community Structure in Subtropical Low Mountain Forests

“…Previous studies involving soil organic matter characterization using 13 C nuclear magnetic resonance (NMR) at the same study site showed greater recalcitrant tannin and polyphenol contents in coniferous plantations (C. konishii and C. formosana) than in BROAD-Nat forest [28]. The resistance of coniferous litter to decomposition may contribute to the accumulation of C and N in soil.…”

Invasion of moso bamboo into a Japanese cedar plantation affects the chemical composition and humification of soil organic matter

“…Data acquisition happened at the conditions of spectrometer frequency 100.46 MHz, spectra width 20,000 Hz, spinning speed 7,000 Hz, contact time 6 ms, pulse delay time 1 s, and with 8,200 scans329. The five chemical shifts were 0–50 ppm (alkyl-C), 50–90 ppm (O-alkyl-C), 90–110 ppm (Di-O-alkyl-C), 110–165 ppm (aromatic-C), and 165–190 ppm (carboxyl-C)1529.…”

Climatic Control on Plant and Soil δ13C along an Altitudinal Transect of Lushan Mountain in Subtropical China: Characteristics and Interpretation of Soil Carbon Dynamics

“…About 12,000 scans were collected for soil samples and 10,000 scans for litter samples [26]. The chemical shift regions 0–45 ppm, 45–110 ppm, 110–160 ppm, and 160–220 ppm were assigned to alkyl C, O-alkyl C, aromatic C, and carboxylic C, respectively [24], [27].…”