Afforestation effects on SOC in former cropland: oak and spruce chronosequences resampled after 13 years

Abstract

Chronosequences are commonly used to assess soil organic carbon (SOC) sequestration after land-use change, but SOC dynamics predicted by this space-for-time substitution approach have rarely been validated by resampling. We conducted a combined chronosequence/resampling study in a former cropland area (Vestskoven) afforested with oak (Quercus robur) and Norway spruce (Picea abies) over the past 40 years. The aims of this study were (i) to compare present and previous chronosequence trends in forest floor and top mineral soil (0-25 cm) C stocks; (ii) to compare chronosequence estimates with current rates of C stock change based on resampling at the stand level; (iii) to estimate SOC changes in the subsoil (25-50 cm); and (iv) to assess the influence of two tree species on SOC dynamics. The two chronosequence trajectories for forest floor C stocks revealed consistently higher rates of C sequestration in spruce than oak. The chronosequence trajectory was validated by resampling and current rates of forest floor C sequestration decreased with stand age. Chronosequence trends in topsoil SOC in 2011 did not differ significantly from those reported in 1998, however, there was a shift from a negative rate (1998: -0.3 Mg C ha(-1) yr(-1) ) to no change in 2011. In contrast SOC stocks in the subsoil increased with stand age, however, not significantly (P = 0.1), suggesting different C dynamics in and below the former plough layer. Current rates of C change estimated by repeated sampling decreased with stand age in forest floors but increased in the topsoil. The contrasting temporal change in forest floor and mineral soil C sequestration rates indicate a shift in C source-sink strength after approximately 40 years. We conclude that afforestation of former cropland within the temperate region may induce soil C loss during the first decades followed by a recovery phase of yet unknown duration.

The carbon sequestration potential of China's grasslands

“…On the contrary, decreased C density/CSP resulting from the five restoration practices associated with conversions from croplands back to grasslands or shrublands was similar to the results of a resampling study and meta‐analysis, which revealed that afforestation in former croplands can decrease SOC stocks (Bárcena et al. , Fujisaki et al. ), probably due to the accelerated decomposition of SOC caused by fresh C inputs (Fontaine et al.…”

Evaluating the carbon sequestration potential of volcanic soils in South Iceland after birch afforestation

“…The results indicate that afforestation by mountain birch, and the establishment of birch woodlands, can increase the bulk SOC stock (0-30 cm), which is in accordance with the findings of Bárcena et al, (2014). They are, however, contrary to the results of Ritter (2007), who studied afforestation on heathland.…”

Changes in Physical and Chemical Properties of Calcic Chernozem Affected by Robinia pseudoacacia and Quercus robur Plantings

“…It was noted that soil organic carbon sequestration increases with the planting age (Berthrong et al, 2012;Boussougou et al, 2010;Jiao et al, 2011). Coincidently, it has been observed that soil carbon loss may occur in the first decades after planting of tree species and is followed by a recovery stage of unknown duration (Bárcena et al, 2014). It was found that the carbon sequestration value is largely determined by the species composition within tree plantations (Gurmesa et al, 2013).…”