CATTANIO, J. H.

SÁ, T. D. de

VIELHAUER, K.

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No. 74An alternative method for determination of total primary production in ditTerent ages ofsecondary vegetation in NE AmazonCattanio, J. Henrique (I), Sá, Tatiana D. de (2) and Vielhauer, Konrad (I)Institutions: (I) Georg-August Universitãt Gõttingen, Gõttingen, Deutschland, (2)Embrapa Amazonia Oriental,Belém, PA, BrasilThe "capoeira" (secondary vegetation) is a common example of modified area in the Amazon rainforest,however is an efficient form to recover the potential of agricultural productivity. In this direction, theaccompaniment of the increment of primary productivity, in such a way aerial as underground, in these modifiedecosystems, becomes the important tools to assist in the agreement of the cycle of nutrients and water as well asin carbon accumulation.The objective of this work is to supply an efficient tool of accompaniment of the primary productivity followingthe leaf area index (LA1) and the root increment index (RII) in three different ages of "capoeira". This work wascarried through in the Igarapé-Açu, Pará, in producer's fellow areas (SHIFT - project ENV25). The dominantground are Ultisols (Kandiudults-USDA-soil taxonomy). The LA1 was evaluated not destructively, a time permonth, through the analyzer of canopy LAI-2000, Li-Cor, that it measures through an optic sensor the diffuselight attenuated by the canopy, and converts it, through mathematical procedures, in values of leaves area(m'j/soil area (m'). The monthly measurement was carried through in three parcels of 5Omx50m in the"capoeira" of 6 and 10 years old (average height 3.5m and 6.5m, respectively), and in three parcels of 3Omx30min the "capoeira" of 1 year old (average height l.5m). The root increment, was estimated by ingrowths-bags,with 2mm of mesh, full with subsoil previously bolted (mesh of 2mm), installed to the depths of 0-1Ocm, 30, 50,100, 200, 300, and 4oocm. The bags had been initially installed in the beginning of the less rainy and rainyperiod. Six months after de installation, the bags was removed from different depths, and dried at 105°C. Thematerial was weighed, and washed in current water with assist of bolter (mesh 2mm), and the collected rootmaterial was dried at 65°C until constant weight. The RII was calculated considering: RII = total root weight(g)/soil density inside of the bag (g/cm'),The data from LA1 during one year of measurement had shown that "capoeira" of 10 years old demonstratedgreater LAI during all the year. However, our hypothesis did not confirm for "capoeira" of 6 and 1 year old,being that the "capoeira" of 1 year had presented many times bigger LA1 of the one than 6 years old. Also wecan observed that the "capoeira" of 1 and 6 years tend to reduce LAI (1.40 and 1.53 m2/m2, respectively) inaccordance with the reduction of rains. Already the "capoeira" of 10 years, had not exactly presented a sharpreduction in this period (0.95 m2/m2). The results of root increment showed not to exist a clear variation in theroot growth between the winter months (rainier period) and summer (less rainy period), in the three ages ofstudied "capoeira". However, the data show, for all the studied ages, existed an intense root growth in depth,main1y in the depth of 4 m, where it had greater root development in the period less rainy. These result suggestmechanisms of absorption of nutrients and water in deeper layers of the ground, for "capoeira's" species. Wecan't found a relation between LA1 and RII for "capoeria" of 10 and 6 year old, however we found a positivecorrelation, between 100 and 400 em of depth, in "capoeira" of 1 year old.Poster section 4 229

An alternative method for determination of total priomary production in different ages of secondary vegetation in NE Amazon.

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