Carbon accumulation by Pinus sylvestris forest plantations after different periods of afforestation in a semiarid sandy ecosystem

Abstract

The carbon pool is changing in afforestation ecosystems, which vary in their duration since establishment, in many semiarid sand regions. Understanding this is important for the management of the planted forest. The present study explored the dynamics of afforested forest carbon pool in a semiarid sandy ecosystem, northwest China. We studied afforested forests of pine (Pinus sylvestris) of five afforestation ages (20, 30, 40, 50, and 60 years since planting, and bare sand as control), the carbon storage and carbon sequestration rate of the forest aboveground biomass layer, surface litter layer, and soil layer (0-50 cm) were calculated, and the soil water content and soil organic carbon of 0-400 cm soil depth were measured. The results showed that the carbon sequestration rate was highest after 20-30 years, with 0.58 Mg C ha −1 yr −1 in the soil layer (0-50 cm). We found a rate of 0.13 Mg C ha −1 yr −1 in the surface litter layer, and a rate of 20.79 Mg C ha −1 yr −1 in the forest aboveground biomass layer. The carbon storage of the forest aboveground biomass layer was highest after 30-40 years, and the carbon storage of the surface litter increased with time. In the soil layer, the carbon storage at 0-10 cm depth was highest after 60 years, the carbon storage at 20-50 cm depth increased soon after afforestation and then decreased afterward with increasing afforestation ages with the maximum for 20-50 cm occurring after 30-40 years. The total carbon storage [the forest aboveground biomass layer, surface litter layer and soil layer (0-50 cm)] was higher when afforestation ages reached around 30 years, after that it decreased with increasing afforestation age. Our research improves the understanding of the P. sylvestris forest ecosystem carbon sequestration in a semiarid sandy area.

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

“…Quantifying the variability and allocation patterns of C stocks in plantations provide data support for better predictions of C on large scales [21]. Carbon stock estimates of forest ecosystems were reported previously [12][13][14]. However, the magnitude and direction of the changes in C stocks in the soil, litter and biomass across chronosequences of Masson pine plantations and the trade-off between plant and soil systems require further investigation.…”

“…Huang et.al. estimated that the C storage of aboveground biomass was highest after 30-40 years, SOC storage at 0-10 cm and 20-50 cm depths were highest after 60 years and 30-40 years, respectively, and the total carbon storage was higher at 30 years and then decreased with increasing age [13]. Some studies have reported that tree biomass C accounts for more than 55% of the total ecosystem C stocks regardless of stand age [14], others concluded that aboveground biomass contained 61-97 Mg C ha −1 , approximately 24-39% of the total C stocks [15], and ecosystem C dynamics tended to balance between 27 and 39 years [16].…”

Plantation understorey legume functional groups enhance soil organic carbon sequestration by promoting species richness

“…In general, the positive effects of plantation age, USR, and legume functional groups on SOC sequestration should be considered in plantation management. In addition, concerns regarding water resources should also be considered to maintain plantation sustainability in semiarid regions (Z. Huang et al, 2021). Thus, thinning mature plantations (over 20 years old) and introducing legumes in water‐limited regions (MAP less than 500 mm) of the Loess Plateau should be a realistic and comprehensive option to alleviate water consumption and enhance SOC sequestration.…”