Distribution characteristics and influencing factors of soil organic carbon in alpine ecosystems on Tibetan Plateau transect
2007
TIAN Yu-qiang | OUYANG Hua | SONG Ming-hua | NIU Hai-shan | HU Qi-wu
The undisturbed regions along the Qinghai-Tibet road crossing the natural zones of montane desert, alpine meadow-steppe, and montane shrub-coniferous forest were chosen as study area. Soil samples were collected at 23 places and the relations between the influencing factors and distribution of soil organic carbon (SOC) content were studied. The results indicated that the orders of SOC content for the whole soil profile in different vegetation, in the horizontal direction, were showed as below: forest> shrub>meadow>steppe>desert; all the SOC contents of upper 10 cm soil layers in vegetations of forest, shrub and meadow, as well as that of upper 20 cm soil layers in steppe, in the vertical direction, were higher than that of corresponding lower soil layers. However, the SOC content in desert was uniform. The grey correlative analysis between the climatic factors and SOC content in upper part soil showed that the precipitation was the dominant climatic factor affecting the distribution of SOC on the Tibetan Plateau transect. The influence of precipitation on the horizontal distribution of SOC decreases as the increase of precipitation in the horizontal direction. The vertical distribution of SOC along soil profile was greatly affected by precipitation or soil clay content in upper part of soil, as well as was clearly influenced by soil silt content or sand content in lower part of soil. The influences of both soil bulk density and soil pH on the vertical distribution of SOC along soil profile declined gradually. The plant biomass was the most important biotic factor affecting the distribution of SOC.
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