Variability in Carbon Stocks across a Chronosequence of Masson Pine Plantations and the Trade-Off between Plant and Soil Systems

Abstract

Plantations sequester atmospheric carbon dioxide and positively respond to climate change, but the carbon (C) sequestration capacity and the trade-off between plant and soil systems in plantations may vary significantly across a chronosequence. Masson pine (Pinus massoniana Lamb.) plantations were selected to investigate the variability of C stocks in 7-, 14-, and 30-year-old stands. The total ecosystem C stock increased with stand age from 14.82 to 19.21 Mg C. Carbon stocks increased with stand age in the plant system but decreased in the soil system, with the ratio of plant-to-soil C stocks increasing from 0.06 in the 7-year-old plantation to 0.70 in the 30-year-old plantation. Carbon stocks in the first 20 cm of the soil accounted for 44.60%, 43.01%, and 30.18% of the total ecosystem carbon stock in 7-, 14-, and 30-year-old plantations, respectively. The variation trends for the proportions of C stock in soil decreased with soil depth as a result of tree and root growth regardless of stand age. Most C was stored in the stems, which contributed 1.36%, 6.85%, and 29.57% of total ecosystem C stock across the chronosequence. Results of structural equation model indicated that the effect of plant system C stock on ecosystem C stock was far larger than soil system C stock, and saturated hydraulic conductivity (ks) and fractal dimension (D) could be the primary parameters affecting ecosystem C stocks according to redundancy analysis (Variance explained by the variables selected). In summary, the plant system increased biomass C stocks by regulating soil properties to meet their growth requirements, the growth of plants in turn changed the soil organic carbon (SOC) stock, then both regulated ecosystem carbon sequestration in Masson pine plantations.

The effects of vegetation type on ecosystem carbon storage and distribution in subtropical plantations

“…Among the biomass C, tree account for the largest proportion of ecosystem C stock, followed by litter, then shrub and herb, which was consistent with previous studies (Kang et al, 2006;He et al, 2021). However, Zhu et al (2010) showed that the aboveground tree biomass consistently had a larger C pool than soil, which was inconsistent with our results.…”

“…In this study, the average aboveground tree and soil accounted for 42.9 and 43.1% of ecosystem C stocks, respectively. There was a larger soil C pool than aboveground biomass C stock in SSP and SPP, which may be because the ratio of aboveground tree C storage to soil increased with the increase of tree ages (He et al, 2021) and indicates the importance of soil in forest C sequestration.…”

“…Walkley-Black method is a common method for the determination of soil and plant organic C (He et al, 2021;Yang et al, 2023;Zhang et al, 2023). The concentration of organic C varies with soil layers, as well as between soil and plants.…”

“…In addition, the recalcitrance organic matter in the plant samples grounded through 100 meshes can be fully oxidized under the action of excessive H 2 SO 4 and K 2 Cr 2 O 7 , so the determination results are comparable with other results. Therefore, Walkley-Black method was widely used in previous studies related to the determination of organic C concentration (He et al, 2021;Yang et al, 2023;Zhang et al, 2023).…”

Forest Soil Carbon and Climate Changes

“…The Issue includes 15 papers; based on the first author affiliation, the papers originate from Russia (7), China (3), Taiwan (2), Japan (1), South Korea (1) and Canada (1). Several papers were dealing with vegetation effects on soil organic matter [1][2][3][4][5]. Respiration as the second most important process of global carbon cycles was considered by researchers from several countries [5][6][7][8][9][10], including also research dealing with the temperature sensitivity of the respiration process [8,9].…”