Annual report from the Loess Project

At the Annual UK – China CZO programme meeting in Guiyang the Loess project presented an update of how work was going to that point in time, 18 months into the project. The bullet points below summaries this presentation.

Modelling and Managing Critical Zone Relationships between Soil, Water and Ecosystem Processes across the Loess Plateau– Prof Lianhai Wu and Prof Ming’an Shao

  • Recent landscape changes in the Critical Zone of Loess Plateau region
    • Vegetation coverage 2000 – 2014 has been studied; it shows mainly moderate vegetation cover with increase from Northwest to Southeast.
    • Temporal trends in vegetation cover change – with the lengthening of the time period the vegetation cover improved consecutively. The significant vegetation restoration covered 52% of the Loess Plateau mainly distributed in Zones of FOR-GRASS and GRASS during 2000-2014 comparing to that of 2% at the initial stage (2000-2005).
    • Restoration caused significant changes and were reinforced through time
    • Socioeconomic activities had significant influence on ecological restoration effectiveness
      • Negative impact – Population and industrial developments; Population pressure revealed a stronger negative effect in this case. There has been a sharp increase in secondary and tertiary industry since 2007. Secondary industry was the major contributor for this negative effect.
      • Positive impact – The improvements of agricultural economy; Income improving wasn’t the dominant factor.
      • Restoration effectiveness could be enhanced from promoting rural economy.
    • The vertical profile of soil moisture content and nitrate has been measured in the Plateau Critical Zone.
    • Variations of magnetic susceptibility are observed both in the vertical soil profile and across different sites. Precipitation affects soil magnetic property changes, especially for the shallow soils (<30 m)
    • Model development in runoff, soil, C and N losses – revisiting the SCS-CN method.
    • Changwu’s long-term data has been used to validate SPACSYS. SPACSYS predicted well the yield for normal and wet years; dynamics were well captured, good agreement with the experiments and LAI peak well predicted.
      • N and C budgets using SPACSYS with Changwu’s long-term data show denitrification and leached loss are small. SOC is decreasing suggesting winter wheat monoculture is not sustainable.