5 documents found, page 1 of 1
Age-dependent leaf physiology and consequences for crown-scale carbon uptake du...
Albert, Loren P.; Wu, Jin; Prohaska, Neill; Camargo, Plínio Barbosa de; Huxman, Travis E.; Tribuzy, Edgard Siza; Ivanov, Valeriy Yu; Oliveira, Rafael S.Satellite and tower-based metrics of forest-scale photosynthesis generally increase with dry season progression across central Amazônia, but the underlying mechanisms lack consensus. We conducted demographic surveys of leaf age composition, and measured the age dependence of leaf physiology in broadleaf canopy trees of abundant species at a central eastern Amazon site. Using a novel leaf-to-branch scaling appro...
Forest structure along a 600 km transect of natural disturbances and seasonalit...
Schietti, Juliana; Martins, Demétrius L.; Emilio, Thaise; Souza, Priscila F.; Levis, Carolina; Baccaro, Fabricio BeggiatoA negative relationship between stand biomass and the density of stems is expected to develop during the self-thinning process in resource-limited forests; this leads to a large proportion of the total biomass occurring in large trees. Nevertheless, frequent disturbance regimes can reduce self-thinning and the accumulation of large trees. We investigated size–density relationships and the contribution of large ...
Biological processes dominate seasonality of remotely sensed canopy greenness i...
Wu, Jin; Kobayashi, Hideki; Stark, Scott C.; Meng, Ran; Guan, Kaiyu; Tran, Ngoc Nguyen; Gao, Sicong; Yang, Wei; Restrepo-Coupé, Natalia; Miura, TomoakiSatellite observations of Amazon forests show seasonal and interannual variations, but the underlying biological processes remain debated. Here we combined radiative transfer models (RTMs) with field observations of Amazon forest leaf and canopy characteristics to test three hypotheses for satellite-observed canopy reflectance seasonality: seasonal changes in leaf area index, in canopy-surface leafless crown fr...
Leaf development and demography explain photosynthetic seasonality in Amazon ev...
Wu, Jin; Albert, Loren P.; Lopes, Aline Pontes; Restrepo-Coupé, Natalia; Hayek, Matthew N.; Wiedemann, Kenia T.; Guan, Kaiyu; Stark, Scott C.In evergreen tropical forests, the extent, magnitude, and controls on photosynthetic seasonality are poorly resolved and inadequately represented in Earth system models. Combining camera observations with ecosystem carbon dioxide fluxes at forests across rainfall gradients in Amazônia, we show that aggregate canopy phenology, not seasonality of climate drivers, is the primary cause of photosynthetic seasonality...
Optimizing the remote detection of tropical rainforest structure with airborne ...
Almeida, Danilo Roberti Alves de; Stark, Scott C.; Shao, Gang; Schietti, Juliana; Nelson, Bruce Walker; Silva, Carlos Alberto; Görgens, Eric BastosAirborne Laser Scanning (ALS) has been considered as a primary source to model the structure and function of a forest canopy through the indicators leaf area index (LAI) and vertical canopy profiles of leaf area density (LAD). However, little is known about the effects of the laser pulse density and the grain size (horizontal binning resolution) of the laser point cloud on the estimation of LAD profiles and the...