Storage, patterns and controls of soil organic carbon in the Tibetan grasslands

Abstract

The soils of the Qinghai-Tibetan Plateau store a large amount of organic carbon, but the magnitude, spatial patterns and environmental controls of the storage are little investigated. In this study, using data of soil organic carbon (SOC) in 405 profiles collected from 135 sites across the plateau and a satellite-based dataset of enhanced vegetation index (EVI) during 2001-2004, we estimated storage and spatial patterns of SOC in the alpine grasslands. We also explored the relationships between SOC density (soil carbon storage per area) and climatic variables and soil texture. Our results indicated that SOC storage in the top 1 m in the alpine grasslands was estimated at 7.4 Pg C (1 Pg 5 10 15 g), with an average density of 6.5 kg m À2 . The density of SOC decreased from the southeastern to the northwestern areas, corresponding to the precipitation gradient. The SOC density increased significantly with soil moisture, clay and silt content, but weakly with mean annual temperature. These variables could together explain about 72% of total variation in SOC density, of which 54% was attributed to soil moisture, suggesting a key role of soil moisture in shaping spatial patterns of SOC density in the alpine grasslands.

Variations of forest soil organic carbon and its influencing factors in east China

“…We found significant relationships between SOC density and nitrogen, bulk density, and soil texture (Table 6), which was consistent with other findings (Fu et al 2010;Lei et al 2013;Yang et al 2008). In this study, we found SOC density was significantly correlated with soil texture in the mineral horizon.…”

Soil organic carbon in the Sanjiang Plain of China: storage, distribution and controlling factors

“…This is why a significantly negative correlation (r = −0.33, P < 0.01) is observed between MAT and SOCD (Table 3). By contrast, MAT higher than 4.6 • C may increase the vegetation productivity and thus contribute to increasing carbon inputs that override the temperature-induced rise in the soil decomposition rate (Yang et al, 2008). Our results confirm the observation made by Yang et al (2007) that the increasing trend of SOCD from the tropical to cold temperate zone in the eastern part of China is correlated with temperature.…”

“…A geostatistical approach was further used to map the regional pattern of SOC in different soil depth ranges. The method that was used for estimating the regional carbon pool in the present study is different from that used by Yang et al (2008), who estimated SOC storage by correlating SOC content with a remote-sensing vegetation index. Considering the rich ecosystem types of the Sanjiang Plain and coarseresolution remote-sensing imagery, this study used the kriging method to achieve a more accurate estimation of SOC than previous studies (Wang et al, 2002;Yu et al, 2007).…”

“…Plant functional types can significantly impact the vertical distribution of SOC (Jobbágy and Jackson, 2000;Yang et al, 2010). Although the influence of climate, vegetation, and soil texture on SOC storage has been noticed (Chaplot et al, 2010;Liu et al, 2011;Yang et al, 2008), it has been difficult to assess this influence because of large uncertainties in characterizing the distribution of SOC. One reason for this difficulty is a lack of appropriate data.…”

The carbon stock of alpine peatlands on the Qinghai–Tibetan Plateau during the Holocene and their future fate

“…The total carbon stock of QinghaieTibetan peatlands was much smaller than that of boreal and tropical peatlands (Gorham, 1991;Page et al, 2011;Yu, 2012) and that of alpine grasslands on the same plateau (Wang et al, 2002;Yang et al, 2008). However, on the area basis, the carbon concentration of peatland is larger or comparable to the peatlands in other regions (Gorham, 1991;Page et al, 2011;Yu, 2012) and far larger than that in alpine grasslands (Wang et al, 2002;Yang et al, 2008).…”