Study
area
Our study was conducted in areas of Caatinga vegetation in northern
Bahia State, Brazil. Occupying an area of 734,478 km2(Silva et al. , 2004), Caatinga vegetation is part of the global
metacommunity of seasonally dry tropical forests (STDF) (Penningtonet al. , 2009) and represents the largest STDF in the Neotropics
(Queiroz et al. , 2017). The study area covers arboreal-shrub
Caatinga or woody Caatinga of the Great Landscape Units of the Sertaneja
Depression. The sampling area includes the roadsides of BR-235 from the
municipality of Juazeiro to that of Jeremoabo. Roadsides in Brazil are
poorly fenced, except for the main highways that are well-fenced. The
roadside of the study area was completely unfenced before and during the
sampling. The chosen private areas further from roads were completely
unfenced as well. Domestic animals had free access to all studied areas.
So, all studied area is grazed in some extent. The private areas are
located a few kilometers distant from BR-235 inside a set of properties
in the municipality of Canudos. The study site was chosen because of the
roadsides with remaining Caatinga vegetation and because of the
unfragmented and unfenced Caatinga from the roadsides up to the plots
far from the road (i.e., up to 8,5 km from the road). Thus, the chosen
study area presented a very specific situation of free movement of
domestic animals, from the road to the plots, in an uninterrupted
manner, and all plots were grazed by domestic animals to some extent,
especially by goats that were constantly seen during the sampling period
(Figure S1, S2, and S3).
The study area is located between 9°31’ and 10°05’S, and between 38°16’
and 40°07’W, and comprises four municipalities: Jeremoabo, Canudos,
Curaçá and Juazeiro (Figures S1, and S3). According to the Köppen
classification, the regional climate is BSh, typically semiarid, with
mean annual rainfall lower than 550 mm, and elevations between 320-m and
520-m above sea level (Alvares et al. , 2013; Carrión et
al. , 2017). The annual precipitation pattern is irregular,
characterized by years of extreme drought, followed by an occasional
year of torrential rains. Mean temperature varies between 23 to 27o C, mean relative humidity is around 50% and the
evapotranspiration rate is high (Daily & Mitchell, 2000). Despite the
physiognomic variation of the Caatinga, the vegetation of all plots is
patchy with clumps of woody shrubs and trees with a herb layer beneath
(see Carrión et al., 2017).