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.