2.1. Study area
The study was carried out in the SDTF of southwestern Ecuador located in Zapotillo canton within the province of Loja (Fig. 1). This ecosystem lies within the Tumbesian biogeographic region, which extends from the central coast of Ecuador to north-western Peru and forms part of the Tumbes-Choco-Magdalena biodiversity hotspot (Mittermeier et al., 2011). As a consequence of chronic anthropogenic disturbance over decades (if not centuries), most of the original SDTF of the Tumbesian region has been degraded or lost (Mittermeier et al., 2005; Tapia-Armijos et al., 2015). This process of degradation has been more a consequence of low-intensity, chronic use and disturbance of SDTF over time than outright forest conversion to anthropogenic land uses (Jara-Guerrero et al. 2019). The resulting landscape is a mosaic of relatively undisturbed forest fragments, forest fragments with different levels of degradation caused by livestock grazing, selective logging, and firewood extraction, and highly degraded areas nearly devoid of woody vegetation (Tapia-Armijos et al., 2015).
Annual precipitation in the study area ranges from 300-700 mm and mean annual temperature varies between 20-26 °C, with daily temperatures reaching as high as 35 °C during the rainy season (Leal-Pinedo and Linares-Palomino, 2005). The climate is highly seasonal, with a rainy season occurring from January to April and a dry season lasting from May to December (Espinosa et al., 2018). The period from September to November is particularly dry with precipitation generally dropping to below 10 mm per month (Maass and Burgos, 2011). The region is affected by El Niño/Southern Oscillation (ENSO) every 3-7 years, which brings a dramatic rise in ocean surface temperatures and high levels of precipitation (Trenberth, 2019).
According to the geopedological map of Ecuador, soils of the area are primarily Inceptisols, Alfisols and Entisols and are considered eroded and poorly evolved with low to moderate depth, low stoniness, and textures ranging from sandy clay loam to loamy sand with some classfied as loam or sand (Espinosa et al. 2016; MAG, 2019). Elevation of the study sites ranges from 200 to 500 m above sea level.