Disentangling stand and environmental correlates of aboveground biomass in Amazonian forests

Baraloto, Christopher; Rabaud, Suzanne; Molto, Quentin; Blanc, Lilian; Fortunel, Claire; Hérault, Bruno; Dávila, Nállarett; Mesones, Italo; Ríos, Marcos; Valderrama, Elvis; Fine, Paul V. A.

doi:10.1111/j.1365-2486.2011.02432.x

Cited by 172 publications

(234 citation statements)

References 54 publications

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“…In support of this view, AGB has been observed to increase from west to east across the Amazon basin in concert with decreasing rates of forest turnover (the mean of mortality and recruitment rates of trees in the stand), declining soil fertility, and increased wood-specific gravity (Quesada et al, 2012;Baraloto et al, 2011).…”

Section: E Lobo and J W Dalling: Canopy Gap Disturbance In Tropicamentioning

confidence: 93%

Effects of topography, soil type and forest age on the frequency and size distribution of canopy gap disturbances in a tropical forest

Lobo

Dalling

2013

Biogeosciences

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Abstract. Treefall gaps are the major source of disturbance in most tropical forests. The frequency and size of these gaps have important implications for forest ecosystem processes as they can influence the functional trait distribution of tree communities, stand-level aboveground biomass and productivity. However, we still know little about the relative importance of environmental drivers of gap disturbance regimes because existing studies vary greatly in criteria used for defining gaps, in the spatial extent of the study area, and the spatial resolution of canopy height measurements. Here we use lidar (light detecting and ranging) to explore how forest age, topography and soil type affect canopy disturbance patterns across a 1500 ha tropical forest landscape in central Panama. We characterize disturbance based on the frequency distribution of gap sizes (the "gap size distribution"), and the area of the forest affected by gaps (the "gap area fraction"). We found that slope and forest age had significant effects on the gap size distribution, with a higher frequency of large gaps associated with old-growth forests and more gentle slopes. Slope and forest age had similar effects on the gap area fraction, however gap area fraction was also affected by soil type and by aspect. We conclude that variation in disturbance patterns across the landscape can be linked to factors that act at the fine scale (such as aspect or slope), and factors that show heterogeneity at coarser scales (such as forest age or soil type). Awareness of the role of different environmental factors influencing gap formation can help scale up the impacts of canopy disturbance on forest communities measured at the plot scale to landscape and regional scales.

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Section: E Lobo and J W Dalling: Canopy Gap Disturbance In Tropicamentioning

confidence: 93%

Effects of topography, soil type and forest age on the frequency and size distribution of canopy gap disturbances in a tropical forest

Lobo

Dalling

2013

Biogeosciences

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“…This study is based in a permanent vegetation plot network of 74 modified Gentry plots established during 2008-2010 to broadly sample geographic and environmental gradients in lowland tropical forests of South America (Baraloto et al 2011). The plot network represents a factorial design, with multiple replicates in Loreto, Peru, and French Guiana, of the three broad habitat classes (SF, TF, and WS).…”

Section: Study Sites and Plot Networkmentioning

confidence: 99%

“…Overall, the 12 focal plots represent almost the entire range of variation in environmental factors observed in the plot network (Baraloto et al 2011).…”

Section: Leaf Production and Herbivory Censusesmentioning

confidence: 99%

Herbivory, growth rates, and habitat specialization in tropical tree lineages: implications for Amazonian beta‐diversity

Lamarre

Baraloto

Fortunel

et al. 2012

Ecology

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Abstract. Tropical plant diversity is extraordinarily high at both local and regional scales. Many studies have demonstrated that natural enemies maintain local diversity via negative density dependence, but we know little about how natural enemies influence beta-diversity across habitats and/or regions. One way herbivores could influence plant beta-diversity is by driving allocation trade-offs that promote habitat specialization across resource gradients. We therefore predicted that increasing resource availability should be accompanied by increasing herbivory rates and decreasing plant allocation to defense. Second, relative abundances within plant lineages are predicted to reflect patterns of habitat specialization and allocation tradeoffs. A phylogenetic context is vital not only to compare homologous plant traits (including defense strategies) across habitat types, but also to connect evolutionary trade-offs to patterns of species diversification in each phylogenetic lineage.We tested these predictions for trees in white-sand, clay terra firme, and seasonally flooded forests in Peru and French Guiana that represent the range of soil fertility, forest structure, and floristic compositions found throughout the Amazon region. We established 74 0.5-ha plots in these habitats and sampled all trees. Within 12 representative plots we marked newly expanding leaves of 394 saplings representing 68 species, including the most abundant species in each plot in addition to species from five focal lineages: Swartzia and Inga (Fabaceae), Protieae (Burseracaeae), Bombacoideae (Malvaceae), and Micropholis (Sapotaceae). We measured total leaf production rates for each sapling and calculated relative herbivory impact as the ratio between herbivory rate and leaf production rate.Herbivory rates averaged 2.1% per month, did not correlate with leaf production rate, and were similar across habitats. Relative herbivore impacts exceeded leaf production rates for most species. Leaf production rate averaged 2.8%, was significantly higher in seasonally flooded forests than the other two habitats, and exhibited significant correlations with specific leaf area. Species with high herbivory rates exhibited significantly lower relative abundances in terra firme forests. Overall, focal species within lineages present contrasting patterns regarding their herbivory rates and leaf production rate within habitats. These results highlight why a lineage-based approach is necessary when attempting to connect hypotheses regarding evolutionary trade-offs to community assembly patterns.

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“…Variation in forest biomass across the Amazon basin (15-17) has been shown to correlate with DSL (16)(17)(18) (Fig. 1), soil texture (16), shifts in stem turnover rate (19), and forest composition (20).…”

mentioning

confidence: 99%

Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change

Levine

Zhang

Longo

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

182

179

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Amazon forests, which store ∼50% of tropical forest carbon and play a vital role in global water, energy, and carbon cycling, are predicted to experience both longer and more intense dry seasons by the end of the 21st century. However, the climate sensitivity of this ecosystem remains uncertain: several studies have predicted large-scale dieback of the Amazon, whereas several more recent studies predict that the biome will remain largely intact. Combining remote-sensing and ground-based observations with a size-and age-structured terrestrial ecosystem model, we explore the sensitivity and ecological resilience of these forests to changes in climate. We demonstrate that water stress operating at the scale of individual plants, combined with spatial variation in soil texture, explains observed patterns of variation in ecosystem biomass, composition, and dynamics across the region, and strongly influences the ecosystem's resilience to changes in dry season length. Specifically, our analysis suggests that in contrast to existing predictions of either stability or catastrophic biomass loss, the Amazon forest's response to a drying regional climate is likely to be an immediate, graded, heterogeneous transition from high-biomass moist forests to transitional dry forests and woody savannah-like states. Fire, logging, and other anthropogenic disturbances may, however, exacerbate these climate change-induced ecosystem transitions.Amazon forests | biomass | ecological resilience | climate change | ecosystem heterogeneity A mazonia consists of 815 million ha of rainforest, transitional forest, and tropical savannahs; stores approximately half of tropical forest carbon (1); and plays a vital role in global water, energy, and carbon cycling (2). Although uncertainties in climate predictions for the region remain large (3), recent analyses imply that significant portions of the basin will experience both longer and more intense dry seasons by the end of the 21st century (3-6). There is particular concern about southern Amazonian forests that experience longer dry seasons than forests in central and western Amazonia (3) and where a trend of increasing dry season length (DSL) and intensity has already been observed (7). Despite the importance of this region for regional and global climate, the climate sensitivity of the Amazon forests remains uncertain: model predictions range from a large-scale die-back of the Amazon (8, 9) to predictions that the biome will remain largely intact, and may even increase in biomass (10-12). Although some of these differences can be attributed to differences in the predicted future climate forcing of the region (13, 14), accurate predictions of how changes in climate will affect Amazonian forests also rely on an accurate characterization of how the ecosystem is affected by a given change in climate forcing. In this study, we examine the climate sensitivity of the Amazon ecosystem, focusing on the mechanisms underpinning changes in forest dynamics and their implications for the timing and nature of...

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Disentangling stand and environmental correlates of aboveground biomass in Amazonian forests

Cited by 172 publications

References 54 publications

Effects of topography, soil type and forest age on the frequency and size distribution of canopy gap disturbances in a tropical forest

Effects of topography, soil type and forest age on the frequency and size distribution of canopy gap disturbances in a tropical forest

Herbivory, growth rates, and habitat specialization in tropical tree lineages: implications for Amazonian beta‐diversity

Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change

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