Editado por Reinhard Lieberei, Helmut Bianchi, Vera Boehm, Christoph Reisdorff

BRIENZA JUNIOR, S.

DENICH, M.

FOLSTER, H.

VLEK, P. L. G.

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EditorsLayoutPrintingReinhard Lieberei 1, Helmut K. Bianchi 2, Vera Boehm 1, Christoph Reisdorff 11 Universität Hamburg, Institut für Angewandte Botanik, Ohnhorststr. 18, 22609 Hamburg, Germany2 GKSS-Forschungszentrum Geesthacht GmbH,  Max-Planck-Straße 1, 21502 Geesthacht GermanyHelmut K. Bianchi, GKSS, Karsten Bittner, Documedia, Geesthacht, GermanyGKSS-Forschungszentrum Geesthacht GmbH, Geesthacht, GermanyISBN 3-00-010691-XLieberei, R., Bianchi, H-K., Boehm, V., Reisdorff, C., (eds.) 2002: Neotropical Ecosystems, Proceedings of the German-Brazilian Workshop, Hamburg 2000. GKSS-Geesthacht .The publishers give permission to copy single contributions from the Proceedings for personal use exclusively.Copies may be passed on only with the correct specification of the source.The research cooperation has been carried out under the auspices of the German - Brazilian GovemmentalAgreement on the Cooperation in Scientific Research and Technological Development.The issuance of the Proceedings and the production of the CD-ROM was sponsored (Code 0339991) by theThe responsibility for the contents of the contributions is solely the authors'.Federal Ministry of Education and Research German-Brazilian Workshop on Neotropical Ecosystems – Achievements and Prospects of Cooperative ResearchHamburg, September 3-8, 2000Recuperation of Degraded Areas – Summaries of Lectures, Session 5Brienza jun., S.; Denich, M.; Fölster, H. and Vlek, P. L. G.: Enriching Fallow Vegetation in the Eastern Amazon of Brazil towards Improving Land-useSá, T. D. de Abreu and Vielhauer, K.: The Role of Biophysical Information for the Management of Fallow Systems 185In the Eastern Amazon of Brazil, the fallow periods usedafter the slash-and-burn agriculture are been shortened andvary between three to four years or more, depending ondifferent land use pressures. The main reasons for this areuse of inappropriate cultivation technology, social problemsand lack of adequate agricultural polices. As a consequence,there is insufficient time for the fallow vegetation recover.To overcome the problem, planting trees as an enrichmentof fallow vegetation can promote biomass accumulation andbuild a biogeochemical nutrient cycle, reproducing in ashort period, the same vigorous vegetation as found in olderfallow.Different techniques of fallow vegetation enrichment (recrûmethod and line planting), using wood trees, are alreadyviable in some cases in the Brazilian Amazon. But thosemethods tie up the land during the growth of trees, andgenerally taken between 20-30 years. Therefore, this proce-dure is not feasible for small-holders, but rather for forestmanagement units. Under pressure to shorten the fallowperiod two alternatives might be presented. In the first case,a leguminous tree or shrub or cover crop is used to improvesoil conditions for the next cropping period. The plantingdensity is generally high to suppress weed growth,representing a complete spontaneous fallow replacement. Inthe Eastern Amazon of Brazil scenario, the fallowvegetation plays an important role, as a source of energyproduction, medicinal plants, and hunting, among others.The substitution of spontaneous and heterogeneous fallowvegetation with homogeneous fallow may therefore not bein the farmer’s best interest.To study the capability of improving fallow vegetationbiomass, leguminous trees were planted during theagricultural period at different spacing to enrich the laterfallow. The first experiment used Acacia auriculiformis andthe second Acacia angustissima, Clitoria racemosa, Ingaedulis and Acacia mangium. Including both experiments,different ecological studies were done to characterizequantitative and qualitative aspects the different fallowsystems as following: planted trees and fallow vegetationbiomass; above- and belowground carbon storage; nutrientstocks, floristic diversity; soil fauna; rooting- structure andgrowth; rainfall partitioning; ecophysiological variables(stomatal conductance and water potential); light quality;gas emission; soil moisture content; mulch decomposition;N-mineralization; biologically fixed N; N-naturalabundance and 15N-labeling methods. The analysis of theimpact on fallow time reduction showed that the enrichedfallow systems provide in a total of 3 years (1 year cropping+ 2 years of enriched fallow) a biomass accumulationequivalent to up to five years of traditional fallow.Biophysical information may help to improve the manage-ment of fallow systems, and to support the formulation ofpublic policies aiming at the sustainable development ofareas where the fallow vegetation is an importantcomponent of the landscape. A good sequence of keybiophysical studies, attempting to space and time scales,associated to features of the particular fallow systemscenario represents an important step in research/development in that context. A good example of that hasbeen practiced by SHIFT Project Env-25 (Secondary forestsand fallow vegetation in the Eastern Amazonia- functionand management), centered in northeastern Pará state, andis being planned to continue in the next phases of thisproject, tackling on biophysical aspects of fallowvegetation, in the context of the family agriculture practicedfor over a century in that region. During the first phase ofEnriching Fallow Vegetation in the Eastern Amazon of Brazil Towards Improving Land-useBrienza jun., S.1, Denich, M.2, Fölster, H.3 and Vlek, P. L. G.21 Embrapa – Amazônia Oriental, Belém, Brazil2 Universität Bonn, Bonn, Germany 3 Georg-August Universität Göttingen, Göttingen, GermanyThe Role of Biophysical Information for the Management of Fallow SystemsSá, T. D. de Abreu1 and Vielhauer, K.21 Embrapa Amazônia Oriental, Belém, PA, Brazil2 ZEF, Universität Bonn, Bonn, Germany

Enriching fallow vegetation in the eastern Amazon of Brazil: towards improving land-use.

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