ABSTRACT This work aimed to evaluate the effect of sources and doses of nitrogen on the initial growth and quality of Melaleuca alternifolia Cheel (melaleuca) seedlings. The nitrogen sources were: ammonium nitrate, calcium nitrate and ammonium sulfate, established in five doses (0, 50, 100, 150 and 200 mg dm-3 of N) equally parceled out and applied on the 25th, 50th, 75th and 100 days after transplanting. The experiment was arranged in complete randomized blocks, in (3 x 5) factorial design, in red yellow latosol, with four repetitions. After 125 days of transplanting data regarding height, collar diameter, aerial part dry weight and root, and the ratios between height and collar diameter, height aerial part and dry weight, aerial part dry weight and root dry weight and Dickson quality index (IQD) were collected. There were no significant effects from the nitrogen sources, however the doses of N were positive and significant for all traits except for the ratio between height and collar diameter. The best standards of seedlings quality were obtained from the application of 100 mg.dm-3 of N.

RESUMO O trabalho teve como objetivo avaliar o efeito de fontes e doses de N no crescimento e qualidade de mudas de Melaleuca alternifolia Cheel (melaleuca). As fontes de N utilizadas foram nitrato de amônio, nitrato de cálcio e sulfato de amônio em cinco doses (0, 50, 100, 150 e 200 mg dm-3 de N) igualmente parceladas e aplicadas aos 25, 50, 75 e 100 dias após a repicagem. O delineamento estatístico adotado foi o em blocos casualizados, em esquema fatorial (3 x 5), em Latossolo Vermelho-Amarelo, com quatro repetições. Aos 125 dias após a repicagem, foram colhidos dados de altura, diâmetro, massa seca da parte aérea, massa seca de raízes e massa seca total, além das relações altura/diâmetro, massa seca da parte aérea/massa seca de raízes, altura/massa seca da parte aérea e índice de qualidade de Dickson. A aplicação de fertilizantes nitrogenados resultou em ganhos significativos no crescimento e qualidade das mudas. Não houve efeito significativo das fontes, no entanto as doses de N tiveram efeito positivo e significativo para todas as características exceto para a relação altura diâmetro do coleto. O melhor padrão de qualidade das mudas foi obtido com a aplicação de 100 mg.dm-3 de N.

ABSTRACT Afforestation of sites disturbed after bauxite mining is the favorite technique to restore all ecosystem functions. The nature of the tree species used for revegetation of post-mining land can accelerate the recovery of soil organic matter and nutrient cycles. This study aimed to determine the litterfall production, decomposition rate and nutrient content from three types of forest cover ( Eucalyptus , Anadenanthera peregrina , mixed plantation of 16 native species) planted in a bauxite mining area in recovery. Litterfall production was evaluated monthly over 30 months, and the litter mass was assessed twice a year (dry and rainy periods). Total nutrient content was determined from samples grouped by period (dry and rainy). The annual average values for litterfall dry mass and litter mass were higher in Eucalyptus and mixed native. The period (dry or rainy) did not influence litterfall rates in A. peregrina , but Eucalyptus and mixed native presented higher amounts for litterfall during the rainy and dry periods, respectively. Litter accumulation in Eucalyptus was not affected by the season of the year, but mixed native and A. peregrina presented higher litter accumulation in the dry season. Apparent decomposition rates of A. peregrina and mixed native were higher in the rainy season, highlighting the A. peregrina with the highest values compared with the other forest covers. The mixed native presented the highest leaf content of P, K, Ca and Mg in both the litterfall and litter mass, while Eucalyptus had the lowest P, K, Ca, S and N content and the highest C content in the litterfall. Litterfall production is important in degraded areas to ensure the nutrient return to the soil. The data obtained suggest that the cultivation of a mixed of 16 native trees contribute for produce the higher annual litterfall yields, besides produces leaf litterfall of better nutritional quality in relation to P, K, Ca, Mg and S. Therefore, mixed of native trees can be a promising option for reactivation of nutrient cycling and organic matter formation in mined area of bauxite in the Brazilian Atlantic Forest.

ABSTRACT The current study aims to characterize the soil seed banks in a forest under restoration and in a seasonal semideciduous forest remnant, as well as to quantitatively and qualitatively compare them in order to evaluate the seed bank potential to influence the restoration process. In total, 60 samples of soil seed banks were collected in two adjacent forests (30 in a 2.18-ha forest undergoing restoration process based on the planting of seedlings belonging to different tree species, after the forest was subjected to bauxite mining activity; and 30 in a 5.30-ha preserved forest fragment). The soil seed bank of the forest undergoing restoration recorded higher density of emerged seedlings than that of the reference ecosystem. Although the shrub-tree species in the investigated forests lacked floristic similarity, the highly similar dispersal syndrome distribution and the successional category of shrub-tree species in them have indicated that both forests underwent ecological processes. Therefore, the restoration process implemented in the mined area has successfully recovered the soil seed bank after a few years.

Resumo O presente estudo teve como objetivo avaliar a serapilheira acumulada em dois ambientes, uma floresta em processo de restauração, após a mineração de bauxita, e um ecossistema de referência (remanescente de floresta secundária em estágio médio de sucessão), e verificar a relação de variáveis ambientais (abertura de dossel, compactação do solo, regeneração natural) com o acúmulo de serapilheira em ambas florestas. Foram alocadas 30 parcelas de 2 × 2 m em cada uma das duas florestas. No centro de cada parcela coletou-se todo o material orgânico contido em amostras de 0,5 × 0,5 m para posterior obtenção da massa seca. Há dissimilaridade entre as duas florestas, em relação ao estoque de serapilheira e demais variáveis ambientais avaliadas. A floresta em restauração apresentou menor acúmulo de serapilheira que o ecossistema de referência. O maior acúmulo de serapilheira, em ambas florestas, acontece em locais com maior quantidade de indivíduos do estrato de regeneração natural e em locais que apresentam solos menos compactados.

Abstract The present study had as objective to evaluate the accumulated litter in two environments, a forest under restoration, after the bauxite mining, and a reference ecosystem (remaining secondary forest in a midsuccessional stage), and investigate the relationship between environmental variables (canopy opening, soil compaction, natural regeneration) and litter accumulation in both forests. Thirty plots of 2 × 2 m in each forest were allocated. In the center of each plot, all organic material contained in samples of 0.5 × 0.5 m was collected to obtain the dry mass. There is dissimilarity between the two forests, in relation to the litter stock and other environmental variables evaluated. The forest in restoration presents less litter accumulation than the reference ecosystem. The largest litter accumulation in both forests occurs in sites with higher number of individuals in the natural regeneration layer and in sites with lower soil compaction.

RESUMO O objetivo deste trabalho foi caracterizar o banco de sementes do solo em mina de bauxita restaurada dez anos após implantação do projeto de restauração. O estudo foi realizado em uma área onde ocorreu exploração de bauxita e posterior restauração florestal. Foram coletadas 40 amostras de solo superficial (0,25 × 0,30 × 0,05 m) para avaliação do banco de sementes pelo método de germinação em casa de sombra durante seis meses. Emergiram 2.489 plântulas, pertencentes a 69 espécies e 23 famílias botânicas, com densidade de 830 propágulos m–2. As famílias com maior densidade foram Poaceae e Cannabaceae. Houve maior proporção de espécies e indivíduos do grupo ecológico pioneiras e da síndrome de dispersão zoocórica. Não houve semelhança florística entre as espécies do plantio e o banco de sementes. Os resultados mostram que o banco de sementes pode fornecer aporte necessário à recuperação do ambiente após perturbações.

ABSTRACT This study aimed to characterize the soil seed bank in a restored bauxite mine ten years after the restoration project. The study was conducted in a bauxite-exploited mine, which was restored with trees. We collected 40 samples of surface soil (0.25 × 0.30 × 0.05 m) to evaluate soil seed bank by germination method in shade house for six months. Results showed that 2,489 seedlings emerged, belonging to 69 species and 23 botanical families, with a density of 830 seedlings m–2. Poaceae and Cannabaceae were the families with higher density. A larger number of species and individuals were pioneer and zoochoric species. The soil seed bank of the restored area showed no difference in plant density and floristic composition between the border and the core study area. There was no floristic similarity between planted species and the seed bank. Results showed that the seed bank was able to supply species and individuals upon germination.

RESUMO O objetivo deste estudo foi avaliar as mudas de espécies arbóreas plantadas para fins de restauração florestal em uma área pós-mineração de bauxita. Foram alocadas 20 parcelas de 9 × 6 m nas quais foram mensurados diâmetro ao nível do solo, altura e diâmetro da copa das mudas plantadas. Também foram calculados a porcentagem de mortalidade e o valor de importância (VI) das espécies. Foram registrados 540 indivíduos arbóreos vivos (22,9% de mortalidade) e 45 espécies. As espécies com maiores VIs foram Solanum lycocarpum (14,7%) e Schinus terebinthifolius (10,8%). S. terebinthifolius, S. lycocarpum e Joannesia princeps contribuíram com 30,4% de cobertura de copa. A altura média das mudas plantadas variou de 0,40 m a 3,90 m. As espécies utilizadas na restauração da área minerada proporcionaram benefícios ecológicos para a área, como cobertura do solo, atenuando processos erosivos e a invasão por gramíneas exóticas agressivas.

ABSTRACT The aim of this study was to evaluate the seedlings of tree species planted for forest restoration in a bauxite mining. We allocated twenty plots of 9 × 6 m and diameter at ground level, height and canopy diameter of planted seedlings. Also were calculated the mortality percentage and the importance value (VI) species. We recorded 540 alive individuals (22.86% mortality) and 45 species. The species with the highest VIs were Solanum lycocarpum (14.7%) and Schinus terebinthifolius (10.8%). S. terebinthifolius, S. lycocarpum and Joannesia princeps, contributed 30.4% canopy cover. Average height of seedlings planted ranged from 0.4 m to 3.9 m. The species used in the restoration of the mined area provided ecological benefits to the area, such as soil coverage, thus ameliorating erosion and invasion of aggressive exotic grasses.