02734naa a2200253 a 450000100080000000500110000800800410001902400570006010000210011724501890013826000090032752018870033665300240222365300210224765300090226865300090227765300240228665300150231070000280232570000190235370000160237270000230238877300690241120599662021-10-08       2016    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1016/j.scitotenv.2016.06.0252DOI1 aARAUJO, J. K. S.  aAssessment of carbon storage under rainforests in Humic Hapludox along a climosequence extending from the Atlantic coast to the highlands of northeastern Brazil.h[electronic resource]  c2016  aAn understanding of the stock of soil organic carbon (SOC) in the umbric epipedon of Oxisols located in the tropical forests surrounded by a semi-arid region is limited but essential because of their importance in the global cycle of carbon (C). The purpose of this study was to assess the effects of climatic (temperature and rainfall), soil organic matter (SOM) composition and litter on the stability of C in surfaces and subsurfaces in five Humic Oxisols along a 475-km climo sequence from 143 to 963m a.s.l. in a tropical environment in northeastern Brazil. Weassessed vertical changes in SOC; soil total nitrogen (N); C from the microbial biomass; 13C, 15N and the humified composition of SOM; the composition of the humin (HUM) fraction by Fourier Transform Infrared (FTIR); and Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) at depth. The elemental and isotopic composition of the litter samples were analyzed in all areas studied. The results indicated that the current climate and recalcitrant organic compounds are not preponderant factors in the formation of the umbric epipedon, as suggested by the partial influence of temperature and rainfall on SOM. In addition, SOM was dominated by easily decomposable compounds, as indicated by the predominance of aliphatic C-H groups in the HUM fraction in the FTIR spectra; by the thermal oxidation through DSC-TG, which revealed that approximately 50% of the HUM was composed easily decomposable compounds; and by the high proportion of organic C present in the microbial biomass. Values of 13C showed a predominance of C3 plant-C in SOM where as 15N patterns indicated that N dynamics differ among the profiles and drive the accumulation of C. These findings can help to characterize the susceptibility of these soils to changes in climate and land use and the implications for the sequestration of soil C.  aBiomassa microbiana  aCarbono profundo  aFTIR  aLixo  aNitrogênio do solo  aSemiárido1 aSOUZA JÚNIOR, V. S. de1 aMARQUES, F. A.1 aVORONEY, P.1 aSOUZA, R. A. da S.  tScience of The Total Environmentgv. 568, p. 339-349, Oct. 2016.