4.2 Controlling process of soil chemical characteristic and
climate factors on SOC in alpine deserts
Over 6% of the world’s land is affected by the salinity across 100
countries mostly in arid and semiarid regions (Datta et al., 2020,
Martínez-García et al., 2020). Deserts soils play a vital role in
regulating greenhouse gases concentrations in the atmosphere (Drahorad
et al., 2013, Topa et al., 2021). Desert grasslands use may improve the
status of soil organic carbon and nitrogen dynamics (Frac et al., 2020).
Nitrogen is essential to regulate the ecosystem functions and services
(Ke et al., 2018). A close spatial similarity was observed between SOC
contents and total nitrogen (Motaghian and Mohammadi 2012). SOC was
significantly correlate with total nitrogen (r=0.997, P<0.01)
in the desert of Minqin (Wang et al., 2019). In present study, deserts
soil organic carbon contents were also positively driven by total
nitrogen. Nowadays, average annual nitrogen deposition increased by
approximately 8 kilograms per hectare between the 1980s and the 2000s
(Liu et al., 2013). Deserts soil organic carbon contents would increase
significantly with adding nitrogen deposition.
Soil pH can affect the content of soil organic carbon by changing plant
growth and soil respiration (Chen et al., 2019, Berdugo et al., 2020).
The spatial distribution of SOC is related to pH and annual
precipitation in Israel deserts (Drahorad et al., 2013). Desert SOC
contents were negatively correlated with soil pH (Chen et al., 2019). In
addition, we also discovered that soil pH was negatively affected SOC
contents in Qaidam basin. It was because there are different degrees of
salinization in desert ecosystems. Furthermore, growth of vegetation was
seriously restricted by high saline alkali soil, and it greatly reduced
the input of soil organic carbon.
Precipitation was driven factor on SOC contents across the desert
ecosystem of Hexi Corridor (Ke et al., 2018). The SOC concentrations
were significantly positively correlated with annual precipitation in
northern China (Chen et al., 2019). Microbial activity decreased
strongly in saline soils by decreasing osmotic potential at lower water
content (Datta et al., 2020). Mean annual temperature was more important
to determine SOC than other abiotic factors in arid desert grasslands
(Wang et al., 2014). In this study, it was indicated that deserts SOC
was significantly driven by precipitation in Qaidam basin. Over the past
several decades, Tibetan Plateau showed an increase in precipitation
(Piao et al., 2010, Liu et al., 2018). Then, increasing regional
precipitation perhaps decreased desert soils organic carbon storage in
future climate scenarios.