Linking Global Land Use/Land Cover to Hydrologic Soil Groups and Modelling Human-Induced Soil Degradation from 850 to 2015
Abstract
The characteristics of soils control the influence how land use and land cover (LULC) change the global water, energy, and biogeochemical cycles. Plant health, and the exchange of energy, water and biogeochemical components at the surface interface is partly controlled by soil properties. Different soil types modify vegetation responses to existing climate forcings, and each soil type also responds differently to the same land-use practice. Currently, Earth System Models often use single soil columns with averaged properties and the same properties stay constant over time regardless of LULC changes. This leads to uncertainties in assessing LULC impacts. To improve the estimates of land surface change in Earth System Models, we link an existing LULC dataset to four hydrologic soil groups from 850 to 2015, based on demonstrated soil preferences for eight LULCs under current conditions. We conclude that humans prefer hydrologic soil groups (HSGs) in order from B, D, C, to A (generally from high to low silt content). This ranking was applied to construct the history of LULC on each soil type at the half-degree grid resolution. Results primarily distribute croplands to HSG B in 850, while HSG A has the most undisturbed area. Over time, preferred soils (HSGs B and D) experience increased use for cropland areas, while poor soils (HSGs C and A) are occupied predominantly by increasing areas in grazing land and secondary non-forests.
To quantify human LULC impacts, we collected published literature of human impacts of agriculture, pasture, grazing, and vegetation harvest on soil properties, including soil texture, soil organic carbon (SOC), and bulk density. Under each LULC unit, we defined the combined impact of LULC, management, climate (represented by NPP), SOC content, and soil texture on each soil property based on observations and multivariable regression models. Finally, based on the established LULC and soil relations from 850 to 2015, we altered soil properties in each soil group according to global variations of impact factors to model human-induced soil degradation. Vertical and temporal variations are applied based on observations. Results demonstrate how soil degradation occurs under historical LULCs and provide better land surface characteristics to improve Earth systems modeling.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC53H1229W
- Keywords:
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- 1622 Earth system modeling;
- GLOBAL CHANGE;
- 1990 Uncertainty;
- INFORMATICS;
- 3275 Uncertainty quantification;
- MATHEMATICAL GEOPHYSICS