Abstract
Forest soils sequester a large amount of carbon (C) and have a significant effect on the global C balance. Forests are commonly managed to maintain certain age structures but the effects of this management on soil C pools (kg C m−2) is still uncertain. We compared 40-year-old (1GF) and 24-year-old (2GF) plantations of Larix principis-rupprechtii in North China. Specifically, we measured environmental factors (e.g., soil temperature, moisture, and pH), the active C and nitrogen (N) pools (e.g., soil organic C, soil total N, dissolved organic C and N, microbial biomass C and N), and soil processes (e.g., C mineralization and microbial activity in different seasons) in five soil layers (0–50 cm, 10 cm for each soil layer) across the growing seasons in three 25 m × 25 m plots in each age class (1GF and 2GF). Findings indicated that the soil organic C pool in the older 1GF forest (12.43 kg C m−2) was significantly higher than 2GF forests (9.56 kg C m−2), and that soil temperature in 1GF forests was 9.8 °C, on average, 2.9% warmer than temperature in 2GF forests. The C lost as carbon dioxide (CO2) as a result of mineralization in the 2GF plots may partly explain the lower soil organic C pool in these younger forests; microorganisms likely drive this process.
Highlights
IntroductionSoils hold 411~2111 Pg C (Tian et al, 2015)
Soils hold 411~2111 Pg C (Tian et al, 2015). This storage and the stabilization of soil carbon (C) pools is crucial for the atmospheric CO2 balance (Paustian et al, 2016) and for soil structure, biological activity, and nutrient and water cycles, all of which lead to more productive soils (Lal, 2011; Seremesic et al, 2011)
Of the total mineral soil organic C (SOC), 5% belongs to the labile fraction; a 1% reduction in soil labile organic C (LOC) pool could result in an efflux of 0.75 × 1015 g of C to atmosphere (Zou et al, 2005)
Summary
Soils hold 411~2111 Pg C (Tian et al, 2015). This storage and the stabilization of soil carbon (C) pools is crucial for the atmospheric CO2 balance (Paustian et al, 2016) and for soil structure, biological activity, and nutrient and water cycles, all of which lead to more productive soils (Lal, 2011; Seremesic et al, 2011). Soil C pools account for about half of the C, with forest soils accounting for much of that C storage (Post et al, 1982). Soil C pools act as both C sources and sinks in their regulation of the global C balance. Soil temperatures and active carbon components as key drivers of C stock dynamics between two different stand ages of Larix principis-rupprechtii plantation.
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