title: A large-scale field assessment of carbon stocks in human-modified tropical forests.
abstract: Tropical rainforests store enormous amounts of carbon, the protection of which represents a vital component of efforts to mitigate global climate change. Currently, tropical forest conservation, science, policies, and climate mitigation actions focus predominantly on reducing carbon emissions from deforestation alone. However, every year vast areas of the humid tropics are disturbed by selective logging, understory fires, and habitat fragmentation. There is an urgent need to understand the effect of such disturbances on carbon stocks, and how stocks in disturbed forests compare to those found in undisturbed primary forests as well as in regenerating secondary forests. Here, we present the results of the largest field study to date on the impacts of human disturbances on above and belowground carbon stocks in tropical forests. Live vegetation, the largest carbon pool, was extremely sensitive to disturbance: forests that experienced both selective logging and understory fires stored, on average, 40% less aboveground carbon than undisturbed forests and were structurally similar to secondary forests. Edge effects also played an important role in explaining variability in aboveground carbon stocks of disturbed forests. Results indicate a potential rapid recovery of the dead wood and litter carbon pools, while soil stocks (0-30 cm) appeared to be resistant to the effects of logging and fire. Carbon loss and subsequent emissions due to human disturbances remain largely unaccounted for in greenhouse gas inventories, but by comparing our estimates of depleted carbon stocks in disturbed forests with Brazilian government assessments of the total forest area annually disturbed in the Amazon, we show that these emissions could represent up to 40% of the carbon loss from deforestation in the region. We conclude that conservation programs aiming to ensure the long-term permanence of forest carbon stocks, such as REDD+, will remain limited in their success unless they effectively avoid degradation as well as deforestation.
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.
authors.forename: Erika
authors.initials: E
authors.lastname: Berenguer
authors.forename: Joice
authors.initials: J
authors.lastname: Ferreira
authors.forename: Toby Alan
authors.initials: TA
authors.lastname: Gardner
authors.forename: Luiz Eduardo Oliveira Cruz
authors.initials: LE
authors.lastname: Aragão
authors.forename: Plínio Barbosa
authors.initials: PB
authors.lastname: De Camargo
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Cerri
authors.forename: Mariana
authors.initials: M
authors.lastname: Durigan
authors.forename: Raimundo
authors.initials: R
authors.lastname: Cosme De Oliveira Junior
authors.forename: Ima Célia Guimarães
authors.initials: IC
authors.lastname: Vieira
authors.forename: Jos
authors.initials: J
authors.lastname: Barlow
mesh_terms: D001938:Brazil; D057486:Carbon Cycle / Q000502:physiology*; D057965:Carbon Sequestration / Q000502:physiology*; D003198:Computer Simulation; D003247:Conservation of Natural Resources / Q000379:methods / Q000706:statistics & numerical data*; D005390:Fires; D016468:Forestry / Q000706:statistics & numerical data*; D065928:Forests; D008954:Models, Biological; D012987:Soil / Q000737:chemistry*; D014329:Tropical Climate
chemical_list: D012987:Soil
keywords: Amazon; REDD+; biomass; forest degradation; logging; secondary forests; soil; vegetation; wildfires