[Storages and distributed patterns of soil organic carbon and total nitrogen during the succession of artificial sand-binding vegetation in arid desert ecosystem].

Soil carbon pool acts as the largest one of carbon pools in the terrestrial ecosystem. The storages and distributed patterns of soil organic carbon (SOC) and total nitrogen (TN) evaluated accurately are helpful to predict the feedback between the terrestrial ecosystem and climate changes. Based on the data about bulk density, content of SOC and TN at 0-100 cm soil profile, the density of SOC and TN at the temporal (chronosequence of artificial vegetation) and spatial (vertical) distributed patterns have been estimated. The results indicated that storages of SOC and TN at 0-100 cm depth increased with the chronosequence of artificial vegetation. The storages of SOC and TN showed the same tendency with the succession time of artificial vegetation. Storages of SOC and TN significantly increased at the early stage of banding sand by artificially vegetation (< 16 a), then piled up at the mid-stage (16-25 a), and markedly increased at the late stage (> 25 a). The variation of storages mainly occurred in the 0-20 cm depth. The storages decreased with the soil vertical depth. At the early stage of banding sand, increase in storage included every depth (0-100 cm). Whereas, at the later stage, increase in storage at 0-20 cm depth was main, and increase in the 20-100 cm was inconspicuous. The accumulation of storage at the shallow soil depth was more notability with the succession of artificial vegetation. The distributed pattern of storage in SOC and TN has been confirmed in arid desert regions below 200 mm annual precipitation. This was beneficial to understand the carbon cycle and to predict the feedback relationship between desert ecosystem and climate changes.

[Spatial variability characteristics of soil organic carbon and nitrogen reveal typical alpine meadow degradation on Qinghai-Tibetan Plateau].

The principle of geo-statistics method was used to analyse the spatial heterogeneity of soil organic carbon and total nitrogen (0-10 cm) of alpine meadow of the Qinghai-Tibetan Plateau. The results show that the mean contents of soil organic carbon and total nitrogen at depth 0-10 cm are 11.45 g x kg(-1) and 1.02 g x kg(-1), 0.23 and 0.21 of co-variation coefficient, respectively. As mentioned above all factors reflect oligotrophic condition of soil fertility at this habitat. Organic carbon and entire nitrogen of soil random factor dissociation take up mutant proportion of general space heterogeneity being 44.7% and 49.9% respectively. Mutant dimension is 210.9 m and 200.1 m respectively. The soil organic carbon and the entire nitrogen show on the research territory vacates to oneself the factor to be bigger than machine the factor the different pattern. On space structure dissociation, from inherent attribute of soil, if space such as soil mineral substance, land form is certainly relevance, the factor and the artificial factor play role if the random factors that be trampled on to soil super crust arouses such as grazing and engineering construction is common, Medium memorial level affecting degree.