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Extreme climatic events affecting the Amazon region are expected to become more frequent under ongoing climate change. In this study, we assessed the responses to the 2010 drought of over 14,000 trees ≥10 cm dbh in a 25 ha lowland forest plot in the Colombian Amazon and how these responses varied among topographically defined habitats, with tree size, and with species wood density. Tree mortality was significantly higher during the 2010-2013 period immediately after the drought than in 2007-2010. The post-drought increase in mortality was stronger for trees located in valleys (+243%) than for those located on slopes (+67%) and ridges (+57%). Tree-based generalized linear mixed models showed a significant negative effect of species wood density on mortality and no effect of tree size. Despite the elevated post-drought mortality, aboveground biomass increased from 2007 to 2013 by 1.62 Mg ha−1 yr−1 (95% CI 0.80-2.43 Mg ha−1 yr−1). Biomass change varied among habitats, with no significant increase on the slopes (1.05, 95% CI −0.76 to 2.85 Mg ha−1 yr−1), a significant increase in the valleys (1.33, 95% CI 0.37-2.34 Mg ha−1 yr−1), and a strong increase on the ridges (2.79, 95% CI 1.20-4.21 Mg ha−1 yr−1). These results indicate a high carbon resilience of this forest to the 2010 drought due to habitat-associated and interspecific heterogeneity in responses including directional changes in functional composition driven by enhanced performance of drought-tolerant species that inhabit the drier ridges. [ABSTRACT FROM AUTHOR]

Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites ( CTFS-Forest GEO) useful for characterizing forest responses to global change. Within very large plots (median size 25 ha), all stems ≥1 cm diameter are identified to species, mapped, and regularly recensused according to standardized protocols. CTFS-Forest GEO spans 25°S-61°N latitude, is generally representative of the range of bioclimatic, edaphic, and topographic conditions experienced by forests worldwide, and is the only forest monitoring network that applies a standardized protocol to each of the world's major forest biomes. Supplementary standardized measurements at subsets of the sites provide additional information on plants, animals, and ecosystem and environmental variables. CTFS-Forest GEO sites are experiencing multifaceted anthropogenic global change pressures including warming (average 0.61 °C), changes in precipitation (up to ±30% change), atmospheric deposition of nitrogen and sulfur compounds (up to 3.8 g N m−2 yr−1 and 3.1 g S m−2 yr−1), and forest fragmentation in the surrounding landscape (up to 88% reduced tree cover within 5 km). The broad suite of measurements made at CTFS-Forest GEO sites makes it possible to investigate the complex ways in which global change is impacting forest dynamics. Ongoing research across the CTFS-Forest GEO network is yielding insights into how and why the forests are changing, and continued monitoring will provide vital contributions to understanding worldwide forest diversity and dynamics in an era of global change. [ABSTRACT FROM AUTHOR]