Changes in soil carbon flux and carbon stock over a rotation of poplar plantations in northwest China

Abstract

Forest soil is a major component of terrestrial ecosystems for carbon sequestration and plays an important role in the global carbon cycle. Soil carbon flux and soil carbon pools were investigated in a poplar plantation chronosequence over a rotation in northwest China. Based on continuous field observation in 2007, the results showed that mean soil CO 2 efflux rate was 5.54, 4.81, and 3.93 lmol CO 2 m À2 s À1 for stands of 2-, 8-, and 15-year-old, respectively, during the growing season. Significant differences in soil respiration of three age classes were mainly because soil temperature, carbon allocation, and fine root growth changed greatly with stand age. Multiple regression analysis suggested that soil temperature and fine root biomass in the upper layer could explain 78-85% of the variation in soil respiration. Mineral soil C stock at 0-40 cm depth was 55.77, 55.09, and 58.14 t ha À1 in the 2-, 8-, and 15-year-old stands, respectively. The average rate of soil C sequestration was 0.13 t ha À1 year À1 following afforestation on former crop lands. Although the plantations had similar management practices and soil types since their establishment, many biotic and abiotic factors such as root biomass and turnover rate, soil condition of the plantations had undergone marked changes at different development stages, which could result in the remarkable differences in soil carbon flux and storage over a rotation. Our results highlight the importance of the development stage within a rotation of poplar plantation in assessment of soil carbon budget.

Soil Respiration at Different Stand Ages (5, 10, and 20/30 Years) in Coniferous (Pinus tabulaeformis Carrière) and Deciduous (Populus davidiana Dode) Plantations in a Sandstorm Source Area

“…The average soil respiration rates of these two plantations ranked in the order of 5-year-old > 10-year-old > 30-year-old and 20-year-old, indicating that soil respiration decreased with stand age. This result is consistent with previous studies [14][15][16]25].…”

Carbon Storage in a Eucalyptus Plantation Chronosequence in Southern China

“…The majority of fine-root biomass C occurred in the upper 20 cm soil layer, which was a result of higher concentrations of nutrients in the topsoil [43][44][45], consistent with findings for other forests and tree species [5,6,19].…”

“…Forest ecosystems have been shown to contain 861 ± 66 Pg C, with 383 ± 30 Pg C in soil, 363 ± 28 Pg C in living biomass (above-and belowground), 73 ± 6 Pg C in dead wood, and 43 ± 6 Pg C in litter [3]. Forest plantations make up 7% of the world's forest area and have expanded by approximately 5 million hectares per year between 2005 and 2010, thus having significant impacts on global C cycling [4][5][6]. At current rotation lengths, most forest plantations do not reach their maximum biological storage, so they have great potential for further carbon fixation [6].…”

Variation in soil respiration under the tree canopy in a temperate mixed forest, central China, under different soil water conditions

“…Variation in tree canopy cover can change soil microclimatic environment, soil physicochemical properties as well as soil carbon input and accumulation (Aponte et al 2010;Zhang et al 2011;Cahoon et al 2012). For example, variations in soil temperature and moisture within the forest ecosystem are very likely caused by canopy cover due to canopy shading and rainfall interception, especially for a small precipitation event (Cable and Huxman 2004;McCarthy and Brown 2006;Potts et al 2006b;Emmerich and Verdugo 2008).…”