Productivité aérienne du caféier Agroforestier : effets des arbres d'ombrage et de l'âge des rejets

Abstract : Net primary productivity (NPP) of perennial plantations can be split between growth (G), mortality (L) and exports (Ex), with varying allocations in different ecosystems, particularly if we compare forest or fruit tree plantations. The objective of our study was to evaluate NPP and its partition in a coffee agroforestry plantation in Costa Rica, taking into account the strong intra-plot heterogeneity of stump shoots, resulting from their annual coppicing (1/5 shoots eliminated by selective pruning for rejuvenilisation, according to "selected coppice") and the presence of sparse shade trees. An experimental design was set up to test these two effects, choosing the stump shoot as experimental unit. Shoot biomass, growth, C and N content were obtained by destructive measures and before development, calibration and validation of specific allometric relationships. Mortality was measured over a year with litter traps, all compartments separated. We observed a depletion of aerial and reproductive compartments between young and old shoots (aged 6), confirming the interest of annual coppicing pruning. Shade trees, present at low density (15 trees ha-1) showed little or no effect on our variables of interest. Coffee tree shoot NPP was measured at a relatively low 7.6 Mg ha-1.an-1, compared with other tropical tree plantations (coconut, eucalyptus, etc...), But coffee tree is a shade plant (low photosynthetic output) grown in altitude with cool mean temperatures. Fruit export accounted for 52% of NPP, visible growth (woody parts) for 26% and finally natural mortality for 23%. The coffee tree invests 75% of C in labile compartments (fruits, leaves, flowers) with rapid turnover, indicating that final storage of C is to be found more in dead mass and soil organic matter than in biomass.
Document type :
Master thesis
File URL :
http://docnum.univ-lorraine.fr/prive/SCDSCI_M_2011_AUDEBERT_LOUISE.pdf
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https://hal.univ-lorraine.fr/hal-01877887
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Submitted on : Thursday, September 20, 2018 - 2:46:59 PM
Last modification on : Friday, September 21, 2018 - 1:12:36 AM

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Louise Audebert. Productivité aérienne du caféier Agroforestier : effets des arbres d'ombrage et de l'âge des rejets. Sciences de l'environnement. 2011. ⟨hal-01877887⟩

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