steady-state mosaic of disturbance and succession across an old-growth Central Amazon forest landscape

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 10; pp. 3949 - 3954
• Main Authors: Chambers, Jeffrey Q., Negron-Juarez, Robinson I., Marra, Daniel Magnabosco, Di Vittorio, Alan, Tews, Joerg, Roberts, Dar, Ribeiro, Gabriel H. P. M., Trumbore, Susan E., Higuchi, Niro
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences 05.03.2013; National Acad Sciences
• Series: From the Cover
• Subjects: Amazonia; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biological Sciences; Biomass; Brazil; carbon; Carbon Cycle; Carbon dioxide; Computer Simulation; Disturbance; Ecosystem; Forest ecosystems; Forest succession; Forestry; Forests; Fundamental and applied biological sciences. Psychology; General aspects; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Landsat; landscapes; magnesium; Models, Biological; Mortality; Old growth forests; Physical Sciences; Probability distribution; Remote sensing; Rivers; Simulation; simulation models; Stochastic models; Street trees; Synecology; time series analysis; tree mortality; Trees; Trees - growth & development; Trees - metabolism; Tropical Climate; Tropical forests; Tropical rain forests; Amazonia; South America; Brazil; Amazon Basin; America; Community structure; NEP NEE NBP; Dynamic characteristic; Forest zone; Tropical zone; Tropical rain forest; gap dynamics; Biodiversity; Climatic zone; Steady state; Vegetation succession; Canopy gap; Disturbed ecosystem; community composition; Primary forest
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1202894110

Old-growth forest ecosystems comprise a mosaic of patches in different successional stages, with the fraction of the landscape in any particular state relatively constant over large temporal and spatial scales. The size distribution and return frequency of disturbance events, and subsequent recovery processes, determine to a large extent the spatial scale over which this old-growth steady state develops. Here, we characterize this mosaic for a Central Amazon forest by integrating field plot data, remote sensing disturbance probability distribution functions, and individual-based simulation modeling. Results demonstrate that a steady state of patches of varying successional age occurs over a relatively large spatial scale, with important implications for detecting temporal trends on plots that sample a small fraction of the landscape. Long highly significant stochastic runs averaging 1.0 Mg biomass⋅ha ⁻¹⋅y ⁻¹ were often punctuated by episodic disturbance events, resulting in a sawtooth time series of hectare-scale tree biomass. To maximize the detection of temporal trends for this Central Amazon site (e.g., driven by CO ₂ fertilization), plots larger than 10 ha would provide the greatest sensitivity. A model-based analysis of fractional mortality across all gap sizes demonstrated that 9.1–16.9% of tree mortality was missing from plot-based approaches, underscoring the need to combine plot and remote-sensing methods for estimating net landscape carbon balance. Old-growth tropical forests can exhibit complex large-scale structure driven by disturbance and recovery cycles, with ecosystem and community attributes of hectare-scale plots exhibiting continuous dynamic departures from a steady-state condition.