Seasonal leaf dynamics in an Amazonian tropical forest

Malhado, Ana C. M.; Costa, Marcos Heil; Lima, Francisca Zenaide De; Portilho, K.; Figueiredo, Daniel N.

doi:10.1016/j.foreco.2009.06.002

Cited by 49 publications

(48 citation statements)

References 25 publications

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“…This indicates that saplings used in the study (1 to 3-m tall) can take over a century to reach a minimum of 100 mm in diameter at breast height. LAI values found in this study are within the range (3.5 to 6) reported by others (Aragão et al, 2005;Malhado et al, 2009;Caldararu et al, 2012) for the Amazon region.…”

Section: Plant Growth In Response To Variation In Forest Canopy Foliagesupporting

confidence: 89%

Do soil fertilization and forest canopy foliage affect the growth and photosynthesis of Amazonian saplings?

Magalhães

Marenco

Camargo

2014

Sci. agric. (Piracicaba, Braz.)

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Most Amazonian soils are highly weathered and poor in nutrients. Therefore, photosynthesis and plant growth should positively respond to the addition of mineral nutrients. Surprisingly, no study has been carried out in situ in the central Amazon to address this issue for juvenile trees. The objective of this study was to determine how photosynthetic rates and growth of tree saplings respond to the addition of mineral nutrients, to the variation in leaf area index of the forest canopy, and to changes in soil water content associated with rainfall seasonality.We assessed the effect of adding a slow-release fertilizer. We determined plant growth from 2010 to 2012 and gas exchange in the wet and dry season of 2012. Rainfall seasonality led to variations in soil water content, but it did not affect sapling growth or leaf gas exchange parameters. Although soil amendment increased phosphorus content by 60 %, neither plant growth nor the photosynthetic parameters were infl uenced by the addition of mineral nutrients. However, photosynthetic rates and growth of saplings decreased as the forest canopy became denser.Even when Amazonian soils are poor in nutrients, photosynthesis and sapling growth are more responsive to slight variations in light availability in the forest understory than to the availability of nutrients. Therefore, the response of saplings to future increases in atmospheric [CO 2 ] will not be limited by the availability of mineral nutrients in the soil.

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Section: Plant Growth In Response To Variation In Forest Canopy Foliagesupporting

confidence: 89%

Do soil fertilization and forest canopy foliage affect the growth and photosynthesis of Amazonian saplings?

Magalhães

Marenco

Camargo

2014

Sci. agric. (Piracicaba, Braz.)

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“…Werneck et al (2001) observed higher litter fall production at the end of the dry season in a forest with different degrees of disturbance in Ouro Preto, MG, Brazil. On the other hand, some authors have observed in the Amazon region greater litter fall production at the end of rainy season (MALHADO et al, 2009;SILVA et al, 2009). Chave et al (2010) found a positive correlation for litter fall and precipitation in a study in different plots in South America.…”

Section: Ferreira ML Et Almentioning

confidence: 90%

Litter fall production and decomposition in a fragment of secondary Atlantic Forest of São Paulo, sp, southeastern Brazil

et al. 2014

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Litter fall consists of all organic material deposited on the forest floor, being of extremely important for the structure and maintenance of the ecosystem through nutrient cycling. This study aimed to evaluate the production and decomposition of litter fall in a secondary Atlantic forest fragment of secondary Atlantic Forest, at the Guarapiranga Ecological Park, in São Paulo, SP. The litter samples were taken monthly from May 2012 to May 2013. To assess the contribution of litter fall forty collectors were installed randomly within an area of 0.5 ha. The collected material was sent to the laboratory to be dried at 65 °C for 72 hours, being subsequently separated into fractions of leaves, twigs, reproductive parts and miscellaneous, and weighed to obtain the dry biomass. Litterbags were placed and tied close to the collectors to estimate the decomposition rate in order to evaluate the loss of dry biomass at 30, 60, 90, 120 and 150 days. After collection, the material was sent to the laboratory to be dried and weighed again. Total litter fall throughout the year reached 5.7 Mg.ha-1.yr-1 and the major amount of the material was collected from September till March. Leaves had the major contribution for total litter fall (72%), followed by twigs (14%), reproductive parts (11%) and miscellaneous (3%). Reproductive parts had a peak during the wet season. Positive correlation was observed between total litter and precipitation, temperature and radiation (r = 0.66, p<0.05; r = 0.76, p<0.05; r = 0.58, p<0.05, respectively). The multiple regression showed that precipitation and radiation contributed significantly to litter fall production. Decomposition rate was in the interval expected for secondary tropical forest and was correlated to rainfall. It was concluded that this fragment of secondary forest showed a seasonality effect driven mainly by precipitation and radiation, both important components of foliage renewal for the plant community and that decomposition was in an intermediate rate.

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“…Studies have shown that this was an issue for high-biomass areas for collections 3 and 4, but this has been considerably improved for collection 5 . Ground based values of LAI in the Amazon basin range from 3.5-6 m 2 m −2 (Malhado et al, 2009;Aragão et al, 2005;Roberts et al, 1996;Meir et al, 2000), with values of up to 10 m 2 m −2 registered by some studies (Doughty and Goulden, 2008), with differences arising from the different measurement methods. MODIS LAI values are in the range 2-6 m 2 m −2 , which provides us with some confidence that there are no major saturation problems.…”

Section: Modis Lai Datamentioning

confidence: 99%

“…Ground-based studies have reported an increase in leaf litterfall during the dry period (Malhado et al, 2009;Chave et al, 2010), but without simultaneous measurements of leaf gain we cannot determine whether the increased litterfall represents a net loss of leaves. Studies using space-borne vegetation data (Myneni et al, 2007;Huete et al, 2006) have reported an increase in greenness during the dry season over the Amazon, even during severe droughts , but these drought observations have been disputed (Samanta et al, 2010;Doughty and Goulden, 2008).…”

Section: Introductionmentioning

confidence: 98%

“…However, the majority of the world's forests retain leaves year round: boreal forests which are dominated by evergreen needle-leaf trees and often mixed with deciduous broadleaf and needle-leaf species; and mesic tropical forests, dominated by evergreen broadleaf species, which are responsible for the majority of terrestrial carbon fixation (Malhi and Grace, 2000). Observed LAI over these evergreen forests, particularly over the tropics, still show seasonal and yearto-year variations (Myneni et al, 2007), but we lack knowledge about the magnitude, geography, timing, and the processes driving such variation, partly reflecting the difficulty of taking year-round measurements.…”

Section: Introductionmentioning

confidence: 99%

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Inferring Amazon leaf demography from satellite observations of leaf area index

2012

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Abstract. Seasonal and year-to-year variations in leaf cover imprint significant spatial and temporal variability on biogeochemical cycles, and affect land-surface properties related to climate. We develop a demographic model of leaf phenology based on the hypothesis that trees seek an optimal leaf area index (LAI) as a function of available light and soil water, and fit it to spaceborne observations of LAI over the Amazon basin, 2001Amazon basin, -2005. We find the model reproduces the spatial and temporal LAI distribution whilst also predicting geographic variation in leaf age from the basin centre (2.1 ± 0.2 years), through to the lowest values over the deciduous eastern and southern Amazon (6 ± 2 months). The model explains the observed increase in LAI during the dry season as a net addition of leaves in response to increased solar radiation. We anticipate our work to be a starting point from which to develop better descriptions of leaf phenology to incorporate into more sophisticated earth system models.

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Seasonal leaf dynamics in an Amazonian tropical forest

Cited by 49 publications

References 25 publications

Do soil fertilization and forest canopy foliage affect the growth and photosynthesis of Amazonian saplings?

Do soil fertilization and forest canopy foliage affect the growth and photosynthesis of Amazonian saplings?

Litter fall production and decomposition in a fragment of secondary Atlantic Forest of São Paulo, sp, southeastern Brazil

Inferring Amazon leaf demography from satellite observations of leaf area index

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