Impact of degradation and fragmentation in plant diversity of native vegetation in agricultural matrices: A case in the Argentine Dry Chaco.

Over the past fifty years, rapid agricultural expansion in the Argentine Chaco region has replaced climax dry forests with extensive grain monocultures, a process primarily documented via remote sensing. This situation has caused a severe landscape imbalance that threatens remaining native vegetation, compromising crucial ecosystem services, like biodiversity connectivity, soil stability, and natural bio-hydrological networks. This scenario is currently particularly acute in Salta province; this study analyses vegetation degradation processes and the impacts of fragmentation in a highly anthropized watersheds dominated by rain-fed agriculture.

A monitoring protocol was established covering native forest and vegetation remnants and adjacent crop fields to evaluate floristic composition, structural deterioration, and edge effects. Ground-based biophysical sampling was integrated with high-resolution aerial imagery obtained via drone to assess vegetation disturbance dynamics and soil surface properties.

Native vegetation has been reduced to less than 5% of the sub-basin's surface area, leaving forest patches completely isolated within the agricultural matrix the connection between them it´s loss. The remnants have degraded into impoverished secondary forests dominated by opportunistic life forms; herbs, climbers, and shrubs make up the bigger percentage of the floristic composition, while canopy trees account for only a little one. Microclimatic alterations resulting from intense edge effects (concentrated within the first 50 meters) inhibit natural regeneration and foster heavy shrub enrichment. The wetland depressions suffer the highest degree of degradation, whereas relictual transition forests exhibit greater structural resilience. The results show that the landscape has crossed critical connectivity thresholds, creating severe biological barriers that disrupt seed dispersal and the movement of seed-dispersing fauna. The severe structural collapse of these remnants prevents natural ecological succession. To mitigate degradation in productive landscapes like the Argentine Chaco, it is essential to implement ecosystem restoration at intermediate scales, such as watersheds, rather than individual plots.