Agroforestry systems recover tree carbon stock faster than natural succession in Eastern Amazon, Brazil

The potential of agroforestry systems (AFS) for atmospheric carbon sequestration in degraded tropical lands is of key interest for climate change and rural development policies. This study evaluated aboveground and soil (0–20 cm) carbon stocks of AFS, secondary forests (SF), conserved and logged mature forests, on 88 sites in the eastern Brazilian Amazon. Tree carbon stock was higher in young (< 10 years) and advanced (> 30 years) AFS (10.2 ± 2.0 and 47.2 ± 8.1 Mg ha−1, respectively) when compared to the same age SF (5.8 ± 2.5 and 26.5 ± 19.5 Mg ha−1). However, aboveground and total carbon stocks were statistically similar within the same age categories of AFS and SF, because shrub pool were higher in SF. Conserved mature forests had the highest carbon stocks (190.2 ± 11.0 Mg ha−1), and carbon stocks in logged mature forests (119.4 ± 5.1 Mg ha−1) were similar to the advanced stages of AFS (108.6 ± 7.5 Mg ha−1). Litter and soil organic carbon (SOC) did not differ significantly between land-use systems nor along succession. At 30 years, aboveground carbon recovery was 46% (± 16) in AFS and 35% (± 21) in SF. Vegetation structural diversity (measured by DBH and height variation) was a good predictor of aboveground carbon stocks. Our results show the potential of AFS for carbon recovery, especially in the tree pool at late stages of development. Structurally more complex AFS provide an alternative to recover degraded lands and to develop synergies between climate change mitigation, adaptation, and goods production in Amazon.