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Vertical variation in photosynthetic parameters in two different tropical forest ecosystems
Knaepen, Wouter
Janssens, Ivan A. (Universiteit Antwerpen)
Verryckt, Lore (Universiteit Antwerpen)
Universiteit Antwerpen Plant and Vegetation Ecology

Data: 2016
Descripció: 46 p.
Resum: Forests contribute to the carbon balance as the largest vegetative sink for atmospheric carbon (CO2). Anthropogenic emissions are counteracted by carbon sequestration in trees, but nutrients could be limiting photosynthesis and the effect could possibly be not as large as believed. In tropical forests, phosphorus (P) is only available from weathered bedrock and is thereby in an imbalance with the rising levels of carbon and nitrogen in the atmosphere. If P is limiting carbon uptake in tropical forests, global carbon cycle models are likely overestimating uptake by forests. Another overestimation might be to only conduct photosynthesis measurements on sunlit leaves of the canopy and take this as an overall canopy average, whilst a vertical profile in photosynthesis is very likely. Our study was conducted on two sites of the Amazonian rain forest in French Guiana. Photosynthesis and dark respiration (Rd) was measured of 120 trees in 12 plots per site. The plots were situated along a geographical gradient (at top, slope and bottom) to cover a large variety in soil P concentration. We derived the photosynthetic parameters Vcmax and Jmax from the photosynthesis measurements using the Farquhar model (Farquhar et al. , 1980). The measurements were performed at two different height levels in the canopy to investigate the vertical profile. In this study we aimed to relate the spatial and vertical variability to parameters such as leaf P concentration, leaf height, light availability, the specific leaf area and the chlorophyll content (SPAD). Soil P concentrations were correlated with the leaf P concentrations, which indicates P uptake from the soil is limited. There were significant vertical differences in the leaves in Vcmax, Jmax, Rd and leaf P concentrations. We conclude that P limits the photosynthetic capacity in our study areas and vertical profiles of photosynthesis should be taken into account when estimating carbon uptake by a tropical forest ecosystem.
Nota: Número d'acord de subvenció EC/FP7/610028
Nota: Màster project submitted to obtain the degree of Master in Biology, specialisation Biodiversity: conservation and restoration. Universiteit Antwerpen. Faculty of Science. Department of Biology. Academic year 2015-2016
Drets: Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades. Creative Commons
Llengua: Anglès
Document: report
Matèria: Leaf phosphorus ; Photosynthetic capacity ; Vertical profile

46 p, 3.4 MB

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Documents de recerca > Documents dels grups de recerca de la UAB > Centres i grups de recerca (producció científica) > Ciències > CREAF (Centre de Recerca Ecològica i d'Aplicacions Forestals) > Imbalance-P
Documents de recerca > Estudis

 Registre creat el 2016-09-19, darrera modificació el 2017-10-14

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