Forest Canopy Gap Distributions in the Southern Peruvian Amazon

Asner, Gregory P.; Kellner, James R.; Kennedy-Bowdoin, Ty; Knapp, David; Anderson, Christopher B.; Martin, Robert E.

doi:10.1371/journal.pone.0060875

Cited by 121 publications

(178 citation statements)

References 52 publications

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“…3). λ is a quantitative index often used to compare and contrast biomass turnover rates in tropical forests (Gloor et al, 2009;Asner et al, 2013;Chambers et al, 2013). Our results thus suggest that turnover rates are relatively constant when ascending from the lowlands into the montane.…”

Section: Discussionmentioning

confidence: 60%

“…To date, most studies of forest functional and structural patterns have focused on the Amazon lowlands, demonstrating that forest canopy height, aboveground biomass and foliar nutrient concentrations vary by community, soil type and geologic substrate (Quesada et al, 2012;Baker et al, 2004;Fyllas et al, 2009;Asner et al, 2010). A recent study also found that canopy gap-size frequency distributions -a quantitative expression of turnover patterns -are surprisingly constant throughout the southwestern Amazonian lowlands (Asner et al, 2013).…”

Section: G P Asner Et Al: Landscape-scale Changes In Forest Structurementioning

confidence: 99%

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Landscape-scale changes in forest structure and functional traits along an Andes-to-Amazon elevation gradient

et al. 2014

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Abstract. Elevation gradients provide opportunities to explore environmental controls on forest structure and functioning. We used airborne imaging spectroscopy and lidar (light detection and ranging) to quantify changes in threedimensional forest structure and canopy functional traits in twenty 25 ha landscapes distributed along a 3300 m elevation gradient from lowland Amazonia to treeline in the Peruvian Andes. Elevation was positively correlated with lidar-estimated canopy gap density and understory vegetation cover, and negatively related to canopy height and the vertical partitioning of vegetation in canopies. Increases in canopy gap density were tightly linked to increases in understory plant cover, and larger gaps (20-200 m 2 ) produced 25-30 times the response in understory cover than did smaller gaps (< 5 m 2 ). Vegetation NDVI and photosynthetic fractional cover decreased, while exposed non-photosynthetic vegetation and bare soil increased, with elevation. Scaling of gap size to gap frequency (λ) was, however, nearly constant along the elevation gradient. When combined with other canopy structural and functional trait information, this suggests near-constant canopy turnover rates from the lowlands to treeline, which occurs independent of decreasing biomass or productivity with increasing elevation. Our results provide the first landscape-scale quantification of forest structure and canopy functional traits with changing elevation, thereby improving our understanding of disturbance, demography and ecosystem processes in the Andes-to-Amazon corridor.

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Section: Discussionmentioning

confidence: 60%

Section: G P Asner Et Al: Landscape-scale Changes In Forest Structurementioning

confidence: 99%

Landscape-scale changes in forest structure and functional traits along an Andes-to-Amazon elevation gradient

et al. 2014

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“…Except for a few values, most of the power-law exponents of GPP extremes (defined by the 5th percentile or higher) are well in the range between 1.55-1.75, and 1.65-1.95 for overall impact and spatial extent, respectively. Hence, the values for the spatial extent fall in the range of exponents recently estimated for canopy gaps in tropical forests (α = 1.83 ± 0.09; Asner et al, 2013). Low power-law exponents (α < 2.0) imply that the distribution of extremes is largely dominated by few very large events, as has been discussed for the case of canopy gaps (Fisher et al, 2008;Asner et al, 2013).…”

Section: Extreme Events In Gpp Are Power-law Distributedmentioning

confidence: 52%

“…In ecology, power laws most often occur either as bivariate relationships (e.g., population density-body mass; (Marquet et al, 1990)) or frequency size distributions (e.g., body sizes; (Morse et al, 1985)), vegetation patches (Kéfi et al, 2007) fire magnitudes (Turcotte et al, 2002), or canopy gaps (Asner et al, 2013). Earlier attempts to describe disturbance events in form of power laws were restricted to their spatial extent (Fisher et al, 2008;Gloor et al, 2009;Kellner and Asner, 2009;Asner et al, 2013). It has recently been shown that the overall impacts of negative extreme events in fAPAR Zscheischler et al, 2013) and GPP (Zscheischler et al, 2014) can also be well approximated by power laws at the global scale.…”

Section: Extreme Events In Gpp Are Power-law Distributedmentioning

confidence: 99%

Extreme events in gross primary production: a characterization across continents

et al. 2014

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Abstract. Climate extremes can affect the functioning of terrestrial ecosystems, for instance via a reduction of the photosynthetic capacity or alterations of respiratory processes. Yet the dominant regional and seasonal effects of hydrometeorological extremes are still not well documented and in the focus of this paper. Specifically, we quantify and characterize the role of large spatiotemporal extreme events in gross primary production (GPP) as triggers of continental anomalies. We also investigate seasonal dynamics of extreme impacts on continental GPP anomalies. We find that the 50 largest positive extremes (i.e., statistically unusual increases in carbon uptake rates) and negative extremes (i.e., statistically unusual decreases in carbon uptake rates) on each continent can explain most of the continental variation in GPP, which is in line with previous results obtained at the global scale. We show that negative extremes are larger than positive ones and demonstrate that this asymmetry is particularly strong in South America and Europe. Our analysis indicates that the overall impacts and the spatial extents of GPP extremes are power-law distributed with exponents that vary little across continents. Moreover, we show that on all continents and for all data sets the spatial extents play a more important role for the overall impact of GPP extremes compared to the durations or maximal GPP. An analysis of possible causes across continents indicates that most negative extremes in GPP can be attributed clearly to water scarcity, whereas extreme temperatures play a secondary role. However, for Europe, South America and Oceania we also identify fire as an important driver. Our findings are consistent with remote sensing products. An independent validation against a literature survey on specific extreme events supports our results to a large extent.

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“…Our contrasting results may arise from our focus on the occurrence of only relatively big individuals, or then from some local historical reasons that have temporarily reduced the abundance of the species in the forests of the Nauta Formation. Asner et al (2013) reported from southern Peru that lowland rain forest canopy gap fequency and size distribution was practically invariable over different geological surfaces. This together with our results supports the idea that tropical rain forest structure changes much less readily in response to spatial variation in soil nutrient status than species composition does (Tuomisto et al 2003;DeWalt and Chave 2004;Paoli et al 2008).…”

Section: Similar Understorey Structure In Spite Of Edaphic and Florismentioning

confidence: 99%

Similar understorey structure in spite of edaphic and floristic dissimilarity in Amazonian forests

et al. 2015

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Forest structure determines light availability for understorey plants. The structure of lowland Amazonian forests is known to vary over long edaphic gradients, but whether more subtle edaphic variation also affects forest structure has not beenresolved. In western Amazonia, the majority of non-flooded forests grow on soils derived either from relatively fertile sediments of the Pebas Formation or from poorer sediments of the Nauta Formation. The objective of this study was to compare structure and light availability in the understorey of forests growing on these two geological formations. We measured canopy openness and tree stem densities in three size classes in northeastern Peru in a total of 275 study points in old-growth terra firme forests representing the two geological formations. We also documented variation in floristic composition (ferns, lycophytes and the palm Iriartea deltoidea) and used Landsat TM satellite image information to model the forest structural and floristic features over a larger area. The floristic compositions of forests on the two formations were clearly different, and this could also be modelled with the satellite imagery. In contrast, the field observations of forest structure gave only a weak indication that forests on the Nauta Formation might be denser than those on the Pebas Formation. The modelling of forest structural features with satellite imagery did not support this result. Our results indicate that the structure of forest understorey varies much less than floristic composition does over the studied edaphic difference. KEYWORDS: canopy openness; Iriartea deltoidea; Pebas Formation; pteridophytes; stem density Similaridade na estrutura do subosque a despeito de dissimilaridades edáficas e florísticas em florestas da Amazônia RESUMO A estrutura florestal determina a disponibilidade de luz para plantas do subosque. Nas planícies Amazônicas, a estrutura florestal varia com fortes gradientes edáficos. O possível efeito de variações edáficas mais sutis sob a estrutura das florestas não está resolvido. Na Amazônia ocidental, a maioria das florestas não-inundadas crescem em solos derivados de sedimentos relativamente férteis da Formação Pebas ou de sedimentos mais pobres da Formação Nauta. Nosso objetivo é comparar a disponilidade de luz e a estrutura do subosque de florestas crescendo sobre duas formações geológicas. Nós medimos a abertura do dossel e a densidade de troncos de árvores em três classes de diâmetro no nordeste Peruano, totalizando 275 pontos de estudo em florestas de terra-firme representando as duas formações geológicas. Além disso, documentamos as variações na composição florística (samambaias, licófitas e a palmeira Iriartea deltoidea) e utilizamos informações de imagens de satélite Landsat TM para modelar as características estruturais e florísticas das florestas em uma área mais ampla. A composição florística sobre as duas formações foram claramente distintas e isso também pôde ser modelado com as imagens de satélite. Já as observações de campo sobre ...

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Forest Canopy Gap Distributions in the Southern Peruvian Amazon

Cited by 121 publications

References 52 publications

Landscape-scale changes in forest structure and functional traits along an Andes-to-Amazon elevation gradient

Landscape-scale changes in forest structure and functional traits along an Andes-to-Amazon elevation gradient

Extreme events in gross primary production: a characterization across continents

Similar understorey structure in spite of edaphic and floristic dissimilarity in Amazonian forests

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