Research ArticleFOREST ECOSYSTEMS

Defaunation affects carbon storage in tropical forests

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Science Advances  18 Dec 2015:
Vol. 1, no. 11, e1501105
DOI: 10.1126/sciadv.1501105
  • Fig. 1 Simulation pathway of frugivore defaunation on carbon storage.

    We generated downgraded communities with altered species composition. Each simulation had two main steps. First, we simulated directed extinctions induced by defaunation (loss of tree species with seed size ≥12.0 mm) or random extinction (that is, tree species removal independent of seed size). Second, we simulated a compensatory replacement of the individuals by the remaining species pool after defaunation by adding the same number of individuals and basal area removed. Dark blue indicates tree individuals of hardwood species with large seeds (≥12.0 mm) and different trunk diameters, light blue represents other tree species.

  • Fig. 2 Relationships between seed diameter and carbon storage–related traits in animal-dispersed trees.

    The black solid line shows the linear regression fit for the trend and the confidence interval (gray envelopes). The red vertical line indicates the seed diameter threshold of 12 mm. Points represent tree species. (A) Wood density and seed diameter (rs = 0.28, P < 0.001, N = 486). The gray dashed horizontal line indicates a wood density = 0.7 g/cm3. Red points are endangered species with dense wood; orange points are endangered species with light wood; green points are nonendangered species with dense wood (resilient hardwood species); and blue points are nonendangered species with light wood. (B) Maximum tree height (m) and seed diameter (mm) (rs = 0.25, P < 0.001, N = 783). Red points are endangered species, and blue points are nonendangered species.

  • Fig. 3 Carbon deficit after defaunation simulation in Atlantic forest sites.

    (A) Locations of the 31 communities studied. The size of the points represents the magnitude of carbon loss (Mg/ha). (B) Carbon balance after simulated changes in carbon storage capacity in the random (blue) and defaunated (red) scenarios over the 31 selected communities. Initial carbon was used as the 0 or neutral point. A negative balance represents a net carbon loss, and positive values indicate gains in carbon storage. Lines represent the simulated trajectories for each community. The black lines show the mean combined values for all communities in each scenario and their confidence interval. The width of the confidence interval for the random scenario trend was increased 2× to improve visualization.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/1/11/e1501105/DC1

    Fig. S1. Distribution function of seed size diameter (mm) dispersed by the major frugivores in the Atlantic forest, Brazil.

    Fig. S2. Maximum tree height by class of species according to its seed diameter and wood density.

    Fig. S3. Relationship between wood density and seed diameter by dispersal mode.

    Fig. S4. Relationships between abiotic variables and magnitude of carbon loss.

    Fig. S5. Relationships between the compositional variables of each community and its magnitude of carbon loss.

    Fig. S6. Linear regression of the above-ground biomass (AGB) and the proxy for basal area (BA) times the wood specific gravity (WSG) times maximum height for the different types of forest.

    Fig. S7. Diagnostic plots of the regression model using basal area (BA) times the wood specific gravity (WSG) times tree maximum height (MaxHeight) as a proxy for AGB.

    Table S1. Trait information of the 2014 species analyzed (available in the data repository).

    Table S2. Atlantic Forest communities analyzed, their spatial localization in Brazil, and abiotic characteristics.

    Table S3. Spearman correlations among dispersal traits and carbon traits.

    Table S4. T test between carbon loss in random scenarios and defaunated scenarios at different intervals of species removed.

    Table S5. Generalized linear model results showing the influence of abiotical and compositional variables on the magnitude of carbon loss of each community.

    Table S6. Compositional characteristics of Atlantic Forest communities.

    Supplementary code and data file available at

    https://github.com/pedroj/MS_Carbon (DOI:10.5281/zenodo.31880).

    Code file S1. Simulation code in R (Simulation_Code.RMD).

    Code file S2. Read me (Simulation_Code.html).

    Data file S1. Trait information of the 2014 species analyzed (Table S1_Trait Data. xls).

    Data file S2. Community data example for the simulation code (prove_community.csv).

    References (188214)

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Distribution function of seed size diameter (mm) dispersed by the major frugivores in the Atlantic forest, Brazil.
    • Fig. S2. Maximum tree height by class of species according to its seed diameter and wood density.
    • Fig. S3. Relationship between wood density and seed diameter by dispersal mode.
    • Fig. S4. Relationships between abiotic variables and magnitude of carbon loss.
    • Fig. S5. Relationships between the compositional variables of each community and its magnitude of carbon loss.
    • Fig. S6. Linear regression of the above-ground biomass (AGB) and the proxy for basal area (BA) times the wood specific gravity (WSG) times maximum height for the different types of forest.
    • Fig. S7. Diagnostic plots of the regression model using basal area (BA) times the wood specific gravity (WSG) times tree maximum height (MaxHeight) as a proxy for AGB.
    • Table S1. Trait information of the 2014 species analyzed (available in the data repository).
    • Table S2. Atlantic Forest communities analyzed, their spatial localization in Brazil, and abiotic characteristics.
    • Table S3. Spearman correlations among dispersal traits and carbon traits.
    • Table S4. T test between carbon loss in random scenarios and defaunated scenarios at different intervals of species removed.
    • Table S5. Generalized linear model results showing the influence of abiotical and compositional variables on the magnitude of carbon loss of each community.
    • Table S6. Compositional characteristics of Atlantic Forest communities.
    • Supplementary code and data file available at https://github.com/pedroj/MS_Carbon (DOI:10.5281/zenodo.31880).
    • Code file S1. Simulation code in R (Simulation_Code.RMD).
    • Code file S2. Read me (Simulation_Code.html).
    • Data file S1. Trait information of the 2014 species analyzed (Table S1_Trait Data. xls).
    • Data file S2. Community data example for the simulation code (prove_community.csv).
    • References (188–214)

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