Landscape conservation as a strategy for recovering biodiversity: Lessons from a long-term program of pasture restoration in the southern Atlantic Forest

Although ecological restoration has entered the global agenda to reverse different anthropogenic disturbances, we still know little about how this solution interacts with other conservation strategies, to avoid the progressive loss of species and ecosystem services. Here we evaluate one of the pioneering restoration programs in the southern Brazilian Atlantic Forest, where the combination of conservation and restoration efforts has been carried out for 20 years. Specifically, we tested how landscape characteristics, restoration strategies and environmental characteristics affect the results of the restoration of pastures. We established 65 circular plots (total 4.0 ha) along restoration areas (3–10 years) and sampled trees and shrubs composing the canopy (DBH ≥ 5 cm) and understorey (DBH < 5 cm, height > 1.3 m). We analysed the landscape metrics (proportion of old-growth forests in 200, 500 and 1,000 m buffers around each plot; and area and distance of the nearest-neighbouring old-growth forests). We explored the multiple effects of landscape, restoration strategy (reforestation, natural regeneration) and environmental variables (soil, pasture grass types) on the species composition and multiple diversity metrics of restoration areas. The species composition was very similar among restoration ages and restoration strategies. We found positive and strong effects of old-growth forest (200 m buffer) proportion on the species richness and Shannon diversity (canopy and understorey), above-ground biomass (canopy) and functional diversity (understorey) of restoration areas. The restoration strategies affected forest structure, and, in general, the reforestation strategy increased above-ground biomass, Shannon, functional and phylogenetic diversities (in canopy), and percentage of endemic species and biomass (understorey), when compared to natural regeneration. The 20-year experience in the southern Atlantic Forest showed that programs focused on landscape conservation associated with a mixture of restoration strategies (i.e. natural regeneration in larger areas and active restoration in more disturbed sites), can be an efficient strategy to ensure biodiversity and ecosystem services in tropical landscapes. Synthesis and applications. To manage degraded tropical lands and achieve global targets for biodiversity and ecosystem services, it is necessary to first ensure the conservation of natural remnants and then use multiple restoration strategies in less resilient areas.