Ecological and productive variation across a silvopastoral chronosequence under retained tree cover in high-Andean grazing systems

Livestock systems in high-Andean environments can modify vegetation structure and soil conditions through changes associated with grazing management and land use. Silvopastoral systems established under retained tree cover represent an alternative management strategy in these landscapes; however, ecological responses associated with different stages of farmer-managed silvopastoral establishment under high-Andean conditions have received comparatively less attention. This study evaluated soil physicochemical properties, vegetation composition, and pasture productivity across a silvopastoral chronosequence established under retained tree cover in the Amazonas region of Peru. The chronosequence consisted of three silvopastoral systems representing one, four, and seven years since establishment (SPS-1, SPS-4, and SPS-7), while a ten-year open-field grazing system (OF-10) was included as a contrasting grazing condition. Soil properties, vegetation composition, diversity indices, and pasture productivity under dry- and rainy-season conditions were assessed. Significant differences among systems were observed for pH, organic matter, bulk density, nitrate, calcium, magnesium, zinc, and boron concentrations ( p < 0.05). Organic matter decreased from 17.87% in SPS-1 to 5.98% in OF-10, whereas bulk density increased from 0.97 to 1.15 g cm −3 . Silvopastoral systems presented greater vegetation heterogeneity and higher richness values than the open grazing condition. Floristic analyses indicated compositional differentiation among systems, while pasture productivity was greater in SPS-1 and SPS-4 than in OF-10 under both seasonal conditions. These responses indicate that silvopastoral establishment under retained tree cover are associated with soil characteristics, vegetation diversity and promote a more stable forage production relative to the open grazing condition.