Modelling the effect of catena position and hydrology on soil chemical weathering

Abstract

Abstract. The sensitivity of chemical weathering to climatic and erosional forcing is well established at regional scales. However, soil formation is known to vary strongly along catenas where topography, hydrology, and vegetation cause differences in soil properties and, possibly, chemical weathering. This study applies the SoilGen model to evaluate the link between the topographic position and hydrology with the chemical weathering of soil profiles on a north–south catena in southern Spain. We simulated soil formation in seven selected locations over a 20 000-year period and compared it against field measurements. There was good agreement between simulated and measured chemical depletion fraction (CDF; R2=0.47). An important variation in CDF values along the catena was observed that is better explained by the hydrological variables than by the position along the catena alone or by the slope gradient. A positive trend between CDF data and soil moisture and infiltration and a negative trend with water residence time was found. This implies that these hydrological variables are good predictors of the variability in soil properties. The model sensitivity was evaluated with a large precipitation gradient (200–1200 mm yr−1). The model results show an increase in the chemical weathering of the profiles up to a mean annual precipitation value of 800 mm yr−1, after which it drops again. A marked depth gradient was obtained for CDF up to 800 mm yr−1, and a uniform depth distribution was obtained with precipitation above this threshold. This threshold reflects a change in behaviour, where the higher soil moisture and infiltration lead to shorter water transit times and decreased weathering. Interestingly, this corroborates similar findings on the relation of other soil properties to precipitation and should be explored in further research.

Soil-vegetation-water interactions controlling solute flow and transport in volcanic ash soils of the high Andes

“…We attribute this difference to the weak soil moisture seasonality in our study sites (Fig. 4), typical in tropical páramo ecosystems (Mosquera et al, 2022), which results in small ranges (max-min) of soil moisture for cushion plants (≤ 0.09 cm 3 cm -3 ) and tussock grasses (≤ 0.07 cm 3 cm -3 ) in comparison with larger soil moisture ranges from the modeled soil profiles (0.35 cm 3 cm -3 ) (Cipolla et al, 2021;García-Gamero et al, 2022).…”

“…In contrast, Cipolla et al, (2021) found a hysteric relationship between soil moisture and weathering rates in a short-term study and attributed this non-linearity to a memory of past events (wet and dry periods). -Gamero et al, (2022) found a positive relationship between soil moisture and soil weathering using a long-term model. We attribute this difference to the weak soil moisture seasonality in our study sites (Fig.…”

“…Soil water availability can be approached using the ratio of mean annual rainfall to potential evapotranspiration, as illustrated in studies of soil development along climatic gradients (Chadwick et al, 2003;Dixon et al, 2016;Schoonejans et al, 2016) and even at the global scale (Calabrese and Porporato, 2020). While these investigations have recognized the importance of water flux and transport in soil weathering, only a few of them directly assessed how soil water fluxes (Clow and Drever, 1996;Maher, 2010;White et al, 2009) and hydrological processes, like infiltration and storage (Cipolla et al, 2021;García-Gamero et al, 2022), control weathering processes. Moreover, the effect of water balance on soil weathering can be elusive due to the potential influence of less-explored co-evolving soil formation factors, notably lithological and climatic settings (Schoonejans et al, 2016).…”

Tree species on environmental gradients in subtropical forest of northwest Belize, in the Maya Lowlands

“…For example, a drier climate is predicted for Central America (Hidalgo et al, 2013). This could exaggerate the comparative lack of soil water on upper slopes (García-Gamero et al, 2021), which, in turn, can affect nutrient availability (Marschner and Rengel, 2012; Viets, 1967). In particular, soil water is known to affect the availability of the key element phosphorus (O’Connell et al, 2018), and therefore possibly the distributions of species sensitive to phosphorus, along the topographic gradient.…”

Soil–vegetation–water interactions controlling solute flow and chemical weathering in volcanic ash soils of the high Andes

“…Soil water availability can be approached using the ratio of mean annual rainfall to potential evapotranspiration, as illustrated in studies of soil development along climatic gradients (Chadwick et al, 2003;Dixon et al, 2016;Schoonejans et al, 2016) and at the global scale (Calabrese and Porporato, 2020). While these investigations have recognized the importance of water flux and transport in soil weathering, only a few of them have directly assessed how soil water fluxes (Clow and Drever, 1996;Maher, 2010;White et al, 2009) and hydrological processes, like infiltration and storage (Cipolla et al, 2021;García-Gamero et al, 2022), control weathering processes. Moreover, the effect of the water balance on soil weathering can be elusive due to the potential influence of less-explored co-evolving soil formation factors, notably lithological and climatic settings (Schoonejans et al, 2016).…”