Modeling soil and landscape evolution – the effect of rainfall and land-use change on soil and landscape patterns

Abstract

Abstract. Humans have substantially altered soil and landscape patterns and properties due to agricultural use, with severe impacts on biodiversity, carbon sequestration and food security. These impacts are difficult to quantify, because we lack data on long-term changes in soils in natural and agricultural settings and available simulation methods are not suitable for reliably predicting future development of soils under projected changes in climate and land management. To help overcome these challenges, we developed the HydroLorica soil–landscape evolution model that simulates soil development by explicitly modeling the spatial water balance as a driver of soil- and landscape-forming processes. We simulated 14 500 years of soil formation under natural conditions for three scenarios of different rainfall inputs. For each scenario we added a 500-year period of intensive agricultural land use, where we introduced tillage erosion and changed vegetation type. Our results show substantial differences between natural soil patterns under different rainfall input. With higher rainfall, soil patterns become more heterogeneous due to increased tree throw and water erosion. Agricultural patterns differ substantially from the natural patterns, with higher variation of soil properties over larger distances and larger correlations with terrain position. In the natural system, rainfall is the dominant factor influencing soil variation, while for agricultural soil patterns landform explains most of the variation simulated. The cultivation of soils thus changed the dominant factors and processes influencing soil formation and thereby also increased predictability of soil patterns. Our study highlights the potential of soil–landscape evolution modeling for simulating past and future developments of soil and landscape patterns. Our results confirm that humans have become the dominant soil-forming factor in agricultural landscapes.

Evolutionary pathways in soil-landscape evolution models

“…The depths to the Bt horizon also decreased due to erosion on the hillslopes. The erosion increased the spatial variability of the soil properties (Figure 6 in Van der Meij et al, 2020), but because eroded soils cover a larger area than the colluvial soils, the depth to the Bt initially decreased on average in all simulations. The increasing spatial heterogeneity caused strongly divergent evolution in the dry scenarios, while the soil properties in the wet scenario initially followed a convergent pathway.…”

“…Model study This study builds further on the results of Van der Meij et al (2020), who used their SLEM called HydroLorica to simulate the development of soils and landscapes under different rainfall and land use scenarios. A detailed description of the methodology and results is provided in their paper and supplementary information.…”

“…SLEMs are numerical models that simulate a set of pedogenic and geomorphic processes that affect the spatial and temporal development of soils and landscapes (Minasny et al, 2015). Recent development in SLEMs enable a more accurate simulation of driving forces behind soil and landscape development (e.g., Van der Meij et al, 2018) and with that they become increasingly equipped to simulate soil and landscape development in a wide variety of settings, over long timescales (Bouchoms et al, 2017;Bock et al, 2018;Van der Meij et al, 2020;Welivitiya et al, 2019). These developments make SLEMs suitable not only to study past soil-landscape dynamics, but also to evaluate the effect of future changes in climate and land use on soil and landscape properties, such as carbon and nutrient stocks (Minasny et al, 2015).…”

A Spatially Explicit Crop Yield Model to Simulate Agricultural Productivity for Past Societies under Changing Environmental Conditions

“…This offers opportunities to model even at large spatial scales, while making less compromises on the complexity or amount of included processes. As knowledge on soil-landscape functioning is ever increasing [9,[53][54][55], it will be of vital importance to not only expand the theoretical bases, but also keep developing platforms that allow to actually enfold these insights. An important adaptation of the AquaCrop model is that it is now fully hydrologically connected.…”

Impact of Hydro-Climatic Changes on Coastal Dunes Landscape According to Normalized Difference Vegetation Index (The Case Study of Curonian Spit)

“…Therefore, it is hard or sometime impossible to distinguish the only one decisive cause of landscape change. The studies investigating a synergy of landscape forming factors have become more common in recent years [12][13][14]. To sum up, an increased natural tree establishment assumes the need for more detailed investigations in Curonian spit coastal zone.…”