The dynamics of forest recovery after windthrows (i.e., broken or uprooted trees by wind) are poorly understood in tropical forests. The Northwestern Amazon (NWA) is characterized by a higher occurrence of windthrows, greater rainfall, and higher annual tree mortality rates (~2%) than the Central Amazon (CA). We combined forest inventory data from three sites in the Iquitos region of Peru, with recovery periods spanning 2, 12, and 22 years following windthrow events. Study sites and sampling areas were selected by assessing the windthrow severity using remote sensing. At each site, we recorded all trees with a diameter at breast height (DBH) ≥ 10 cm along transects, capturing the range of windthrow severity from old-growth to highly disturbed (mortality > 60%) forest. Across all damage classes, tree density and basal area recovered to >90% of the old-growth values after 20 years. Aboveground biomass (AGB) in old-growth forest was 380 (±156) Mg ha−1. In extremely disturbed areas, AGB was still reduced to 163 (±68) Mg ha−1 after 2 years and 323 (± 139) Mg ha−1 after 12 years. This recovery rate is ~50% faster than that reported for Central Amazon forests. The faster recovery of forest structure in our study region may be a function of its higher productivity and adaptability to more frequent and severe windthrows. These varying rates of recovery highlight the importance of extreme wind and rainfall on shaping gradients of forest structure in the Amazon, and the different vulnerabilities of these forests to natural disturbances whose severity and frequency are being altered by climate change.
Figure. Top left inset: Map demonstrating the mean annual number of rainfall events for the period 1998–2016 obtained using TRMM. The red square indicates the location of the study sites near Iquitos, Perú. Main figure: Map of windthrow severity over the study region. Small black squares indicate the locations of the Nauta, Napo, and Oroza sites (3 ha each). These sites are enlarged in the top right, bottom right, and bottom left inset panels which include transects (black lines) located across the windthrow gradient within each field site.
Contact: Robinson Negron-Juarez (email@example.com), Berkeley Lab
Citation: Urquiza Muñoz JD, Magnabosco Marra D, Negrón-Juarez RI, Tello-Espinoza R, Alegría-Muñoz W, Pacheco-Gómez T, Rifai SW, Chambers JQ, Jenkins HS, Brenning A, Trumbore SE. Recovery of Forest Structure Following Large-Scale Windthrows in the Northwestern Amazon. Forests. 2021; 12(6):667. https://doi.org/10.3390/f12060667.