02458naa a2200205 a 450000100080000000500110000800800410001902400370006010000160009724501430011326000090025652018180026565000110208365000230209465000160211770000210213370000210215470000210217577300560219619821852025-03-14       2013    bl uuuu     u00u1 u    #d7 a10.1097/SS.00000000000000252DOI1 aMOREIRA, A.  aPhosphorus dynamics in the conversion of a secondary forest into a rubber tree plantation in the Amazon rainforest.h[electronic resource]  c2013  aDuring the past several decades, extensive areas of the humid tropical Amazon have been cleared for the introduction of pasture or subsistence farming and later abandoned after a few years of use. An option for recovering these areas is the planting of rubber trees because it is a native tree that could restore conditions similar to those existing before the clearing. In addition, the high economic value of natural rubber is a source of income for small producers. In soil management under the Amazon conditions, low phosphorus (P) has been the most limiting factor. Under natural conditions, P is provided to the plants almost exclusively by organic matter mineralization. The aim of this study was to evaluate a chronosequence of reforestation with rubber trees planted at different times in cleared areas, with primary forest as a reference. The amounts of litter and P content in the plant, in the litter, and in soil, as well as biological indicators (acid and alkaline phosphatase and P microbial biomass) associated with the P cycle in a Xanthic Ferralsol (Oxisol), in the Central Amazon were assessed. Rubber tree growth resulted in changes in total organic carbon, with an increase of 104.6% in the 45-year-old rubber trees compared with the 6-year-old rubber tree plantation. This was also observed for acid and alkaline phosphatase activities, which were close to those of the primary forest. The formation of litter and the P content of the microbial biomass in soil were higher in rubber areas. The P immobilized into microbial biomass was the main reserve to meet the plant's nutritional demand for phosphorus. The content of P available in the soil, regardless of the extractants (Mehlich 1, Mehlich 3, and Bray 1) and the age of vegetation cover were below the levels indicated as appropriate.  aRubber  aHevea Brasiliensis  aSeringueira1 aMORAES, L. A. C.1 aZANINETTI, R. A.1 aCANIZELLA, B. T.  tSoil Sciencegv. 178, n. 11, p. 618-625, Nov. 2013.