EUCAMIX

Intensification écologique des plantations d'eucalyptus par association d'espèces légumineuses arborées fixatrices d'azote.

This project has been conducted in close relationship with the ANR-Systerra « Intens&Fix » project.

A global increase in wood demand is observed worldwide that is more and more satisfied by forest plantations and especially, in Brazil, by eucalypt plantations (EP). However, their ability to meet wood demand is limited by competing land uses and their sustainability is a major concern with regard to serious long-term N and P deficits. Introducing N2-fixing species in FP may increase stand production, and N and P availability in the soil. The project proposes innovative alternatives to pure EP to provide high and sustainable level of wood production with reduced fertilizer applications, and positive environmental impacts. The project develops an experimental approach on mixed plantations of Eucalyptus sp. and Acacia mangium in experimental stations and a network of trials in commercial companies. The study links water, C, N and P cycles, and the ecological processes involved in their regulation, within both pure and mixed EP. The biological interactions within and between the components of the system (trees, micro-organisms, soil) are studied and quantified with respect to the use of natural resources. The project contributes to the production of refined methodological techniques, documentation of competition/facilitation mechanisms for N and P bioavailability, and provides ecological intensification - based silviculture, adapted for large areas of EP in Brazil.

Objectives

The production of Eucalyptus plantations must increase in a sustainable way, through innovative practices that are attractive for stakeholders. The overall objective of the project was the ecological intensification of Eucalyptus plantations through the association of the N₂-Fixing-tree Acacia mangium to increase Eucalyptus plantations productivity and soil N and P availability. The specific objective was to address the inter- and intra-specific biophysical interactions within Eucalyptus plantation mixed with A. mangium.

First results

The balance between positive and negative interactions drives wood production and C allocation among tree compartments. Lasting N facilitation and complementarity between species in mixture of Eucalyptus and Acacia mainly depends on the absence of water deficit. Nitrogen and P soil functioning and soil biodiversity rapidly change after A. mangium introduction.

Publications

Bachega L.R., Bouillet J.P., Piccolo M.C., Saint-André L., Bouvet J.M., Nouvellon Y., Gonçalves J.L.M., Robin A., Laclau J.P., 2016. Decomposition of Eucalyptus grandis and Acacia mangium leaves and fine roots in tropical conditions did not meet the Home Field Advantage hypothesis. Forest Ecology and Management. 359, 33-43.

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Bouillet J.P., Laclau J.P., Gonçalves J.L.M., Voigtlaender M., Gava J.L., Leite F.P., Hakamada R., Mareschal L., Mabiala A., Tardy F., Levillain J., Deleporte P., Epron D., Nouvellon Y., 2013. Eucalyptus and Acacia tree growth and stand production over a full rotation in single- and mixed-species plantations across 5 sites in Brazil and Congo. Forest Ecology and Management, 301, 89–101.

Bini D., dos Santos C, Bouillet J.P., Gonçalves, J.L.M, Cardoso, E.J.B.N, 2013. Eucalyptus grandis and Acacia mangium in monoculture and intercropped plantations: Evolution of soil and litter microbial and chemical attributes during early stages of plant development. Applied soil Ecology, 63, 57-66.

Epron D., Nouvellon Y., Mareschal L., Moreira R.M., Koutika L.-S., Geneste B., Delgado-Rojas J.S., Laclau J.P., Sola G., Gonçalves J.L.M., Bouillet J.P., 2013. Partitioning of net primary production in Eucalyptus and Acacia stands and in mixed-species plantations: a comparison in two contrasting tropical environments. Forest Ecology and Management, 301,102–111.

Laclau J.P., Nouvellon Y., Reine C., Gonçalves J.L.M., Krushe A.V., Jourdan C., le Maire G., Bouillet J.P., 2013. Mixing Eucalyptus grandis and Acacia mangium trees leads to transgressive fine root over-yielding and exclusion of the weakest competitor from resource-rich soil layers. Oecologia, 172, 903–913.

le Maire, G., Nouvellon, Y., Christina, M., Ponzoni, F.J., Gonçalves, J.L.M., Bouillet, J.P., Laclau, J.P., 2012. Tree and stand light use efficiencies over a full rotation of single- and mixed-species Eucalyptus grandis and Acacia mangium plantations. Forest Ecology and Management. 288, 31-42.

Nouvellon Y., Laclau J.P., Epron D., Le Maire G, Bonnefond J.M., Gonçalves J.L.M., Bouillet J.P., 2012. Production and carbon allocation in monocultures and mixed-species plantations of Eucalyptus grandis and Acacia mangium in Brazil. Tree Physiology 32, 680-695.

Paula R.R., Bouillet J.P., Trivelin P.C.O., Zeller B., Gonçalves J.L.M., Nouvellon N., Bouvet J.M., Plassard C., Laclau J.P., 2015. Evidence of short-term belowground transfer of nitrogen from Acacia mangium to Eucalyptus grandis trees in a tropical planted forest. Soil Biology and Biochemistry 91, 99-108.

Voigtlaender M., Laclau J.P., de Gonçalves J.L.M., de Piccolo M.C., Moreira M.Z., Nouvellon Y., Ranger J., Bouillet J.P., 2012. Introducing Acacia mangium trees in Eucalyptus grandis plantations: Consequences for soil organic matter stocks and nitrogen mineralization. Plant and Soil 352, 99-111.

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