Change of Soil Carbon Fractions and Water-Stable Aggregates in a Forest Ecosystem Succession in South China

In order to evaluate the dynamics of carbon storage during forest succession and explore the significance of water relations and soil stability in forest environments, a study was conducted in 2011. This study investigated the dynamics of soil organic carbon (SOC) fractions and its protection through aggregation along the successional forests. An experiment in South China examined pine forest (PF), pine and broadleaved mixed forest (PBMF), and monsoon evergreen broadleaf forest (MEBF), which represent the early, middle, and advanced succession stages, respectively. Soil was sampled at 0–15, 15–30, 30–45, and 45–60 cm depths. We analyzed active, slow, and passive organic carbon, as well as particulate organic matter carbon (POM-C) and nitrogen (POM-N), and measured the weight and concentration of water-stable aggregates in four classes (>2000 μm, 250–2000 μm, 53–250 μm, and <53 μm). The results suggested that various carbon fractions and the percentage of active and passive carbon to total organic carbon (TOC) increased with forest succession. The percentage of water-stable aggregates in >2000 μm (0–15 cm and 15–30 cm) and <53 μm (45–60 cm) in MEBF was significantly higher than in PBMF and PF. The SOC content of all size classes of water-stable aggregates in 0–45 cm were significantly increased with forest succession. In conclusion, forest succession contributed to the accumulation of carbon storage, and the increasing percentage of siltand clay-size (<53 μm) fraction improved the stability of soil organic matter (SOM). OPEN ACCESS Forests 2015, 6 2704