Defining the impact of pine cultivation on soil water content in Zapatoca, Santander, using Electrical Resistivity Tomography (ERT).

This study assesses the impact of pine tree plantations on soil water content in Zapatoca, northeastern Colombia, using multitemporal electrical resistivity tomography (ERT) combined with laboratory analyses. The research compares four land covers: a native tree forest and three pine species in plantation: Pinus maximinoi, Pinus oocarpa and Pinus patula, each of which has distinct physical and chemical soil characteristics. Soil profiles were characterized in terms of texture, bulk density and chemical properties. ERT data were collected at three different times and analysed using Archie's law and generalised Archie's law to estimate volumetric water content. These estimates were validated against direct measurements from soil samples. The results indicate that the native forest retains a higher water content at greater depths, which is associated with a high clay content, a lower canopy density and an absence of surface barriers. In contrast, pine plantations showed shallower moisture retention, potentially due to high evapotranspiration rates, dense canopy cover and physical barriers such as thick layers of pine needles. Multitemporal ERT data effectively captured seasonal changes in subsurface moisture and correlated well with direct measurements; however, estimations were less accurate in silty soils. The findings suggest that pine plantations may reduce water infiltration and recharge, influenced by soil texture, forest management, and canopy structure. These insights highlight the usefulness of ERT in evaluating the hydrological impact of changes in land use and support the development of informed afforestation and conservation strategies.