Soil organic carbon storage and soil CO2 flux in the alpine meadow ecosystem

High-resolution sampling, measurements of organic carbon contents and C-14 signatures of selected four soil profiles in the Haibei Station situated on the northeast Tibetan Plateau, and application of C-14 tracing technology were conducted in an attempt to investigate the turnover times of soil organic carbon and the soil-CO2 flux in the alpine meadow ecosystem. The results show that the organic carbon stored in the soils varies from 22.12x10(4) kg C hm(-2) to 30.75x10(4) kg C hm(-2) in the alpine meadow ecosystems, with an average of 26.86x10(4) kg C hm(-2). Turnover times of organic carbon pools increase with depth from 45 a to 73 a in the surface soil horizon to hundreds of years or millennia or even longer at the deep soil horizons in the alpine meadow ecosystems. The soil-CO2 flux ranges from 103.24 g C m(-2) a(-1) to 254.93 gC m(-2) a(-1), with an average of 191.23 g C m(-2) a(-1). The CO2 efflux produced from microbial decomposition of organic matter varies from 73.3 g C m(-2) a(-1) to 181 g C m(-2) a(-1). More than 30% of total soil organic carbon resides in the active carbon pool and 72.8%. 81.23% of total CO2 emitted from organic matter decomposition results from the topsoil horizon (from 0 cm to 10 cm) for the Kobresia meadow. Responding to global warming, the storage, volume of flow and fate of the soil organic carbon in the alpine meadow ecosystem of the Tibetan Plateau will be changed, which needs further research.

Soil Carbon stocks and schanges in the Republic of Ireland

The soil carbon (C) stock of the Republic of Ireland is estimated to have been 2048 Mt in 1990 and 2021 Mt in 2000. Peat holds around 53% of the soil C stock, but on 17% of the land area. The C density of soils (t C ha-1) is mapped at 2 km*2 km resolution. The greatest soil C densities occur where deep raised bogs are the dominant soil; in these grid squares C density can reach 3000 t C ha-1. Most of the loss of soil C between 1990 and 2000-up to 23 Mt C (1% of 1990 soil C stock)-was through industrial peat extraction. The average annual change in soil C stocks from 1990 to 2000 due to land use change was estimated at around 0.02% of the 1990 stock. Considering uncertainties in the data used to calculate soil C stocks and changes, the small average annual 'loss' could be regarded as 'no change'.