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 have
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 >
5cm) and understory (DBH< 5cm, height > 1.3m). We analyzed
the landscape metrics (proportion of old-growth forests in 200 m, 500m and
1000m buffers around each plot; and area and distance of the
nearest-neighboring 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 understory), aboveground biomass (canopy) and
functional diversity (understory) of restoration areas. The restoration
strategies affected forest structure, and, in general, the reforestation
strategy increased aboveground biomass, Shannon, functional and
phylogenetic diversities (in canopy), and percentage of endemic species
and biomass (understory), 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.