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).