Graduate School, Institute of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, 183-8509, Japan.
Graduate School of Global Environmental Studies, Kyoto University, Kyoto, 606-8501, Japan.
Sci Rep. 2019 Jul 8;9(1):9835. doi: 10.1038/s41598-019-46406-2.
Soil organic carbon (SOC) dynamics after slash-burn agriculture are poorly understood in African tropical forest, though recent studies have revealed C4 grass invasion as a forest understory influences SOC dynamics after deforestation. This study aimed to quantify the relative SOC contribution of C4 and C3 plants separately through the sequential fallow periods of forest (cropland, or 4-7, 20-30, or >50 years of fallow forest) in the tropical forest of eastern Cameroon. We evaluated the SOC stock and natural C abundance for each layer. The SOC stock was largest in 4-7 years fallow forest (136.6 ± 8.8 Mg C ha; 100 cm depth, and C4:C3 = 58:42), and decreased with increasing fallow period. SOC from C4 plants was larger in the 4-7 and 20-30 years fallow forests (57.2-60.4 ± 5.8 Mg C ha; 100 cm depth), while it clearly decreased in >50 years fallow forest (35.0 ± 4.1 Mg C ha; 100 cm depth), resulting in the smallest SOC in this mature forest (106.4 ± 12.9 Mg C ha; 100 cm depth). These findings indicate that C4 grass understories contributed to the SOC restoration during early fallow succession in the tropical forest of eastern Cameroon.
在非洲热带森林中， slash-burn 农业后土壤有机碳（SOC）的动态变化知之甚少，尽管最近的研究表明，C4 草入侵林下会影响森林砍伐后的 SOC 动态。本研究旨在通过东喀麦隆热带森林的连续休耕期（耕地或 4-7 年、20-30 年或>50 年休耕森林），分别量化 C4 和 C3 植物对 SOC 的相对贡献。我们评估了每个土层的 SOC 储量和自然 C 丰度。在 4-7 年休耕林（136.6±8.8 Mg C ha；100 cm 深度，C4:C3=58:42）中 SOC 储量最大，并随休耕期的延长而减少。C4 植物的 SOC 在 4-7 年和 20-30 年休耕林（57.2-60.4±5.8 Mg C ha；100 cm 深度）中较大，而在>50 年休耕林（35.0±4.1 Mg C ha；100 cm 深度）中明显减少，导致成熟森林中的 SOC 最小（106.4±12.9 Mg C ha；100 cm 深度）。这些发现表明，C4 草林下在东喀麦隆热带森林的早期休耕演替过程中有助于 SOC 的恢复。
