Changes in floristic composition and structure in a cerrado sensu stricto area were studied over a 9-y period. A sample of 19 (20-m × 50-m) permanent plots was assessed at 3-y intervals from 1985 to 1994, when all stems ≥ 5 cm at 0.30 m above the ground level were measured. There was little change in species composition over the period. Changes in density and basal area of the whole community were in the range of 5% over the 9 y. These parameters fluctuated over the years with the greatest differences found in the comparisons of 1991, 2 y after an accidental fire reached the site, with other years. The changes in density and basal area were greater than in several tropical forests, probably due to disturbances such as fire occurring at 3 to 5-y intervals. The nearly constant density and basal area suggested a highly resilient community.

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RESUMO: Foram selecionadas seis áreas de estudo, Estação Ecológica de Águas Emendadas-DF, Parque Nacional de Brasília-DF, APA Gama-Cabeça do Veado-DF, Silvânia-GO, Paracatu-MG e Pat rocínio-MG na Chapada Pratinha (15-20'" S e 46-49~ W), três delas em unidades de conservação e três fora delas. Em cada área foram amostradas 10 parcelas de 1000 m 2 (20xSOm). Todas as árvores a partir de 5 cm de diâmetro na base do tronco foram medidas e identificadas. A florística ea fitossociologia de cada área foi analisada e estas foram comparadas entre si pelos índices de similaridade de S0rense e de Morisita. No total foram encontradas 139 espécies e 42 famílias sendo que ape nas 22 espécies foram comuns a todas as áreas. Leguminosae e Vochysiaceae apresentaram valores de im!XIrtância elevados em todas as áreas. As densidades !XIr ha variaram de 664 a 1396. Os índices de diversidade de Shannon variaram de 3,1 1 a 3.56. As similaridades foram altas pelo índices de Sorensen, de 0,5 a 0,7, !XIrém baixas pelo de Morisita quando se comparou as áreas de Paracatu e Patrocínio com as demais áreas. Foi concluído que as diferenças florísticas e principalmente estruturais foram elevadas entre estas duas áreas que são mais distantes e se situam a menores altitudes do que aquelas si tuadas nas unidades de conservação existentes na chapada sendo sugerida a criação de novas unidades nestes Municípios.

Structural and floristic changes of a fireprotected cerrado sensu stricto are described over a 13-year period. The study site is located in a biological reserve (2,800 ha) surrounded by large Pinus spp. and Eucalyptus spp. plantations (36,000 ha), in southwestern Bahia, Brazil. The region occurs in the outer-core of the Cerrado domain, near the Cerrado-Caatinga ecotone, and is mainly occupied by pasture and cropland. Surveys were carried out in 1991 and 2004 in 13 permanent plots (20 9 50 m). Stems with diameter C5 cm at 0.30 m above ground level were identified and measured. Floristic changes were significant (Søren-seńs index = 0.45). Species number rose from 62 to 84 (35.48%). Alpha diversity increased significantly (P [ 0.001). New species migrated to the area, and there was an expansion of many fire-sensitive species. Woody layer expanded, increasing 19.09% in density and 14.93% in basal area. Diameter distributions followed a ''reversed-j'' pattern on both occasions, but differed (P [ 0.05) due to a significant increase in the first two size-classes, indicating a high recruitment. Community dynamics was high and had a positive balance between recruitment (3.72% yr -1 ) and mortality (1.93% yr -1 ). Conversely, mean annual increment was very small, 0.096 cm yr -1 (SD = 0.14; N = 808). Most species, including many dominant ones, had a positive balance in favor of recruitment and low turnover, indicating that although species immigration rate is high (1.42 spp ha -1 ), structural changes in species composition happens at a much slower pace. The surrounding forest plantations are permeable and do not limit species immigration; and may be connecting the reserve with the larger neighboring natural fragments, providing an abundant source for diaspores, and possibly neutralizing any fragmentation effects. Succession is also influenced by the ecotonal condition. The structure and floristics of the cerrado sensu stricto at this site (under present climatic conditions) is fire-dependent.

RESUMO -O objetivo do trabalho foi estimar o estoque de carbono da parte aérea (troncos, galhos e serapilheira) e subterrânea (raízes e solo) da vegetação lenhosa de um cerrado sensu stricto, localizado na Fazenda Água Limpa, da Universidade de Brasília, Distrito Federal. A área de estudo foi amostrada a partir de parcelas de 20 x 50m alocadas sistematicamente. Em cada parcela foram inventariados todos os indivíduos lenhosos arbóreo-arbustivos, vivos e mortos em pé, com no mínimo 5 cm de diâmetro tomado a 30 cm do solo. Foram realizadas também coletas da biomassa de serapilheira; da biomassa de raízes (fina, média e grossa) e da densidade e teor de carbono no solo. A profundidade máxima adotada para a coleta de biomassa da parte subterrânea foi de 2 m. A maior parte do carbono correspondeu ao compartimento solo (88,7%), superando bastante as raízes (7,3%), onde as concentrações foram de 271,23 e 22,38 toneladas por hectare, respectivamente. Troncos e galhos totalizaram 8,60 toneladas de carbono por hectare e a serapilheira, 3,62 toneladas de carbono por hectare.Palavras-chave: Estoque de carbono, Biomassa e Cerrado sensu stricto. CARBON STOCK IN CERRADO Sensu stricto IN THE FEDERAL DISTRICT ABSTRACT -The objective of this study was to estimate the carbon stock of the aerial section (stems, branches and litter) and belowground (roots and soil) of woody vegetation in a cerrado