Green-up na Estação Seca da Amazônia Central : padrões sazonais da fenologia foliar de uma floresta de terra firme
At an upland primary forest in the Central Amazon, monthly changes in leaf phenology were followed for each of 63 tree crowns for 29 months (September 2010 to January 2013) using a south-looking camera mounted on a tower extending 15-20m above the canopy. Nine categories were recognized of massive c...
| Autor principal: | Tavares, Julia Valentim |
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| Grau: | Dissertação |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/11928 http://lattes.cnpq.br/6941210631272619 |
| Resumo: |
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At an upland primary forest in the Central Amazon, monthly changes in leaf phenology were followed for each of 63 tree crowns for 29 months (September 2010 to January 2013) using a south-looking camera mounted on a tower extending 15-20m above the canopy. Nine categories were recognized of massive changes in leaf color or quantity, occurring in the span of a month. All but four trees underwent at least one of these monthly massive changes over the period of study. Change types were grouped into two larger classes, massive leaf-flushing and massive leaf-drop. Leaf flushing was six times more frequent in the five driest months (June to October) compared to the five wettest months (December to April). The number of flushing trees showed positive correlation with incident photosynthetically active radiation (PAR) and negative correlation with rainfall, suggesting that central Amazon upland forests are resilient in the face of normal dry season stress, optimizing leaf quantity and leaf age to take advantage of greater PAR in the dry season. Soil water content at 100 cm depth never dropped below 41% and this was close to the maximum of 46%, suggesting that drought stress was not a driver of phenology. Twenty-one trees (33%) lost all or most of their leaves at least once. At least three of these were classified as diseased or senescent. For another 16 of these 21, leaf loss was brief – visible in one or rarely two consecutive monthly images – and was a therefore a preamble to leaf flushing. Preparatory leaf drop and subsequent flushing were completed for most flushing trees by the end of the five driest months (October), so the forest canopy as a whole should have more green leaves and fewer epiphylls at this time of year. This is consistent with orbital sensor observations of the Enhanced Vegetation Index reaching a peak at the end of the dry season in the Central Amazon. |