Sazonalidade da renovação de folhas no dossel ao longo de uma topossequência e em ano de seca severa em floresta de terra firme na Amazônia Central
In the central Amazon near Manaus, leaf litter production and canopy leaf stock were measured and new leaf production was inferred, at monthly increments from April 2015 to March 2016, for four upland forest types arrayed along a topographic gradient ranging from poorly drained white sand riparian z...
| Autor principal: | Valle, Dalton Freitas do |
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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/1/5158 http://lattes.cnpq.br/3354137047126970 |
| Resumo: |
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In the central Amazon near Manaus, leaf litter production and canopy leaf stock were measured and new leaf production was inferred, at monthly increments from April 2015 to March 2016, for four upland forest types arrayed along a topographic gradient ranging from poorly drained white sand riparian zone to well drained clay-loam plateau. All four-forest types closely tracked one to another on a monthly basis. Production rates of leaf litter and of new leaves in the canopy during the five driest months were 2.3-2.7 times higher than in the five wettest months, using historical monthly rainfall means. This results in a strong seasonality in the leaf-age structure, previously documented only for central Amazon plateau forests. Detecting the same pattern in all parts of the local upland landscape is important because plateaus occupy less than 50% of the area of central Amazon upland and because seasonal change in leaf age structure is the main driver of seasonality in canopy photosynthetic capacity and Gross Ecosystem Productivity (GEP). Leaf-litter production was more strongly correlated with historical monthly means of two climate variables (rainfall and cloud cover) than with the study period values of these two climate variables, despite of this study was carried out during the most extreme El Nino drought since 1997-98. This suggests that forest phenology is programmed to follow
expected (historical) seasonal climate. A possible exception - a brief response to the study period El Niño - was an anomalous second peak in leaf litter rates during the month 15Sept-15Oct 2015, when accumulated 60-day rainfall reached its lowest level (63 mm) since at least 1998. This second peak in leaf drop was not visible in the monthly averages (2004-2008) of leaf litter data obtained for plateau by TEAM for the same site. Riparian forest had the lowest levels of leaf litter production, of new leaf production, longer leaf residence time and lower specific leaf area, compared to the other three forest
types. The other three forest types were not separable on these attributes. |