Soil Respiration and Organic Carbon Dynamics with Grassland Conversions to Woodlands in Temperate China

Abstract

Soils are the largest terrestrial carbon store and soil respiration is the second-largest flux in ecosystem carbon cycling. Across China's temperate region, climatic changes and human activities have frequently caused the transformation of grasslands to woodlands. However, the effect of this transition on soil respiration and soil organic carbon (SOC) dynamics remains uncertain in this area. In this study, we measured in situ soil respiration and SOC storage over a two-year period (Jan. 2007–Dec. 2008) from five characteristic vegetation types in a forest-steppe ecotone of temperate China, including grassland (GR), shrubland (SH), as well as in evergreen coniferous (EC), deciduous coniferous (DC) and deciduous broadleaved forest (DB), to evaluate the changes of soil respiration and SOC storage with grassland conversions to diverse types of woodlands. Annual soil respiration increased by 3%, 6%, 14%, and 22% after the conversion from GR to EC, SH, DC, and DB, respectively. The variation in soil respiration among different vegetation types could be well explained by SOC and soil total nitrogen content. Despite higher soil respiration in woodlands, SOC storage and residence time increased in the upper 20 cm of soil. Our results suggest that the differences in soil environmental conditions, especially soil substrate availability, influenced the level of annual soil respiration produced by different vegetation types. Moreover, shifts from grassland to woody plant dominance resulted in increased SOC storage. Given the widespread increase in woody plant abundance caused by climate change and large-scale afforestation programs, the soils are expected to accumulate and store increased amounts of organic carbon in temperate areas of China.

Responses of soil respiration to land use conversions in degraded ecosystem of the semi-arid Loess Plateau

“…2) and increased by 7-46% following the conversion of cropland to woodland and grassland, which was in line with previous studies (Frank et al, 2006;Jenkins and Adams, 2010;Wang et al, 2013). This may likely be related to the increase in SOC content and fine root biomass.…”

“…In recent years, considerable effort has been made to understand the influence of the conversion of native forest to cropland or grassland in tropical and subtropical regions (Adolfo Campos, 2006;Fernandes et al, 2002;Sheng et al, 2010) and in temperate regions (Arevalo et al, 2010). Some other studies have also investigated the influence of the conversion between woodland and grassland in temperate regions (Smith and Johnson, 2004;Wang et al, 2013). However, to our knowledge, few studies have focused on the conversion of cropland to woodland or grassland in degraded ecosystems (Rey et al, 2011;Shi et al, 2014).…”

Shifts in the microbial community structure explain the response of soil respiration to land-use change but not to climate warming

“…While afforestation of moorland increased Rs, afforestation of grassland significantly reduced Rs. A number of previous studies reported reductions in Rs upon afforestation of pasture and cropland ScottDenton et al, 2006;Hiltbrunner et al, 2012Hiltbrunner et al, , 2013Wang et al, 2013;Zhang et al, 2013) that was attributed to low C inputs from tree to belowground communities. This observation is consistent with a previous report of considerably lower primary production and soil respiration in forest compared with grassland at the field scale (Schulze et al, 2010).…”

Influence of carbonized crop residue on soil carbon storage in red pepper field

“…Generally, the Rs rate varied seasonally; Rs began to increase in the spring when temperature began to increase, reached its peak value during summer, and decreased thereafter. Such variation has been reported to be attributable to changes in Ts (Koizumi et al, 1999;Buchmann, 2000;Suh et al, 2006;Wang et al, 2013).…”