## 2 Materials and Methods  
### Study Area  
The study area is located in the southern sector of the dry Chaco in central Argentina (Figure 1) and is representative of the Chaco Phytogeographical Province [20]. It includes a protected area (Chancani Provincial Reserve) and surrounding forests with different management regimes and levels of degradation (Figure 1A). Although these forests provide essential ecosystem services to local communities and contribute to the regional economy [46; 47], making them valuable for conservation and sustainable management, the region's permissive and liberal legal regulations fail to prevent deforestation and degradation [48].  
The study area comprises two main geomorphological landscapes: foothills and plains (Figure 1B). The foothills, located on the western slopes of the Sierras de Pocho, range from 370 to 500 m above sea level and have permeable, poorly developed soils. The plains, the most extensive landform, feature gentle slopes of less than 1% and sedimentary deposits with sandy or clayey soils of low fertility, which are prone to erosion [49; 50]. The region has a subtropical xeric climate [51], characterized by a dry season, high evapotranspiration [33],and a mean annual rainfall of 600 mm, mostly occurring between October and April. The average annual temperature is 18 \({}^{\circ}\)C [52].  
The vegetation of the study area includes xerophilous subtropical forests [19] and shrublands [51; 53]. In the foothills, forests are dominated by _Aspidosperma quebracho-blanco_ [PERSON], accompanied by isolated individuals of _Neltuma flexuosa_ ([PERSON]). [PERSON] and [PERSON], _Sarcomphalus mistol_ ([PERSON].) [PERSON], _Neltuma torquata_ ([PERSON].) [PERSON], _Neltuma chilensis_ ([PERSON]) [PERSON] and [PERSON], and _Celtis igunaea_ ([PERSON].) [PERSON]. The tree layer can reach heights of up to 15 m and is dominated by _A. quebracho-blanco_, while the shrubby layer, reaching heights of up to 4 m, is primarily composed of _Larrea divaricata_ [PERSON], _Mimozyganthus carinatus_ ([PERSON].) [PERSON], _Senegalia gilliesii_ ([PERSON].) [PERSON] and [PERSON], and _Celtis pallida_ [PERSON].  
In the western plains, forests are co-dominated by _A. quebracho-blanco_ and _N. flexuosa_, with shrub cover exceeding 60%, depending on the level of biodiversity conservation. The dominant shrub species in these areas include _L. divaricata_, _M. carinatus_, _S. gilliesii_, and _C. pallida_. In the southern and central depressed areas, which have higher moisture levels and finer soils, plant communities are dominated by _N. flexuosa_ and _C. pallida_. In the northern  
Figure 1: **(A)** Location of the study area (dotted-line box) within the dry Chaco (gray area). **(B)** Distribution of sampling sites (yellow circles) used for field data collection and Sentinel-2A image analysis across foothills and plains within the Arid Chaco landscape. **(C)** Methodological scheme illustrating field data collection through plot-based surveys and sampling transects. Maps have been prepared on QGIS Development Team (2024). QGIS Geographic Information System (Version 3.34). Open Source Geospatial Foundation Project. Maps Data: Google, ©2024 Airbus.  
saline lowlands, plant communities are dominated by halophilic species such as _Geoffroea decorticans_ (Gillies ex Hook. and Arn.) [PERSON], _Allenrolfea_ spp. [PERSON], _Suueda_ spp., and _Atriplex cordobensis_ [PERSON] and Stuck [50; 54; 55; 56].  
Shrub communities vary in composition and height. Mixed shrublands often exhibit two layers (shrubby and herbaceous) with some isolated trees under 5 m tall (_A. quebracohblanco_ and _N. flexuosa_). The shrubby layer is usually dominated by _L. divariatica, M. carinatus_, and _S. gilliesi_. In significantly degraded areas, the proportion of bare soil is high, while woody species diversity is low. In some locations, woody communities have been replaced by sprayed crops such as potatoes, corn, and wheat or by implanted _Cenchrus ciliaris_ L. (buffel grass) pastures with scattered small trees [57].