No abstract

Recovery of arsenic contaminated areas is a challenge society faces throughout the world. Revegetation associated with microbial activity can play an essential role in this process. This work investigated biological attributes in a gold mining area with different arsenic contents at different sites under two types of extant revegetation associated with cover layers of the soil: BS, Brachiaria sp. and Stizolobium sp., and LEGS, Acacia crassicarpa, A. holosericea, A. mangium, Sesbania virgata, Albizia lebbeck and Pseudosamanea guachapele. References were also evaluated, comprising the following three sites: B1, weathered sulfide substrate without revegetation; BM, barren material after gold extraction and PRNH (private reserve of natural heritage), an uncontaminated forest site near the mining area. The organic and microbial biomass carbon contents and substrate-induced respiration rates for these sites from highest to lowest were: PRNH > LEGS > BS > B1 and BM. These attributes were negatively correlated with soluble and total arsenic concentration in the soil. The sites that have undergone revegetation (LEGS and BS) had higher densities of bacteria, fungi, phosphate solubilizers and ammonium oxidizers than the sites without vegetation. Principal component analysis showed that the LEGS site grouped with PRNH, indicating that the use of leguminous species associated with an uncontaminated soil cover layer contributed to the improvement of the biological attributes. With the exception of acid phosphatase, all the biological attributes were indicators of soil recovery, particularly the following: microbial carbon, substrate-induced respiration, density of culturable bacteria, fungi and actinobacteria, phosphate solubilizers and metabolic quotient.

-The objective of this work was to evaluate the influence of topsoil thickness, shading and origin when performing environmental restoration in a degraded pasture area. The experiment was conducted in a randomized block design with a factorial (3 x 2 x 2) + 2 layout. Treatments consisted of combinations of topsoil origins (forest at early or middle regeneration stages), topsoil thicknesses (10, 20, or 30-cm superficial soil layer), and presence or absence of 70% shading; with two additional control treatments. Surveys on topsoil physical-chemical attributes and flora and soil coverage were conducted. Good correlation was observed between bulk density and total porosity. Vegetation comprised a total of 2,932 individuals of herbaceous, shrub and subshrub plants; 33 species in 11 families and 1 morphospecies were identified. A floristic survey of the tree stratum revealed 235 individuals belonging to 21 species and 14 families, as well as 2 unidentified species. The best natural regeneration index is observed in the 20-cm topsoil layer, where shading exerts a positive influence on the humidity and natural regeneration of the seed bank. Topsoil from middle-stage forest is the most suitable for restoration of degraded pasture areas.

Translocation of rare populations is regarded as the last resort for the conservation of species whose habitat destruction is imminent. The objective of the present study was to evaluate the effect of two height classes and three leaf reduction intensities on growth and increases in height, stem diameter, survival, and new leaf production in seedlings of Aspidosperma cylindrocarpon (peroba) obtained via rescue seedlings in a remnant of tropical semi deciduous forest. We recovered 240 individuals that were divided into two height classes (Class I-5 to 15cm and Class II-20 to 35cm) and subjected to three leaf reduction intensities (0%, 50%, and 100%), which were then transported to a shade house with 50% light reduction. Measurements of height, stem diameter, and new leaf production were collected 8 times at 0, 15, 60, 75, 90, 105, 120, and 135 days, and survival rate was measured at day 135. The average survival rate was 82.9%; 77.5% for one Class I (5-15cm) and 88.3% for Class II (20-35cm). Higher seedling growth was observed for the 0% leaf reduction treatment in both height classes. The leaves insertion were greater in the 100% cuts, with a decrease observed over time. It is advisable to restore A. cylindrocarpon seedlings in two height classes owing to the high survival rate, leaf appearance, and growth reported in the present study. The no-leaf reduction treatment (0%) is the most viable alternative for the production of A. cylindrocarpon seedlings, via rescue seedlings.

Restaurar as florestas tropicais é essencial para enfrentar mudanças climáticas globais, manter e conservar a diversidade e os serviços ecossistêmicos. Foi analisado o estabelecimento e ocupação em três estratégias de restauração florestal (Plantio em Mudas em Área Total (PAT), Ilhas de Diversidade (ID) e Semeadura Direta (SD)) da vegetação florestal associada a cursos d’água.  Foram avaliados: o número de indivíduos, intensidade de perfilhamento, biomassa acima do solo, área de copa, diâmetro e altura médios, por indivíduo, em 58 unidades amostrais (10 x 30 m) distribuídas entre as estratégias após 2,5 anos da implantação. Também foram avaliadas as principais espécies e suas similaridades entre as estratégias. A SD proporcionou maior efetividade quanto ao Número de indivíduos, Biomassa e Área de Copa, enquanto, a intensidade de perfilhamento foi maior nas ID e não houveram diferenças quanto a média de altura e diâmetro. Cada estratégia apresentou um conjunto particular de espécies de maior sucesso e as mais similares foram aquelas que utilizaram mudas (PAT e ID). A estratégia SD destacou-se no estudo, especialmente quando considerados aspectos ecológicos e custos envolvidos. As espécies contribuíram na diferenciação das estratégias, pois, proporcionaram funções ecológicas distintas que influenciam processos ecológicos em nível de comunidade e indivíduos. Palavras-chave: restauração florestal; nucleação; semeadura direta; plantio de mudas; floresta Amazônica.   Effectiveness in the tropical forest restoration: how the differential performance of species and ecological context affect the establishment and occupation   ABSTRACT: Restoring tropical forests is essential to address global climate change, to maintain and conserve diversity and ecosystem services. The establishment and occupation of three forest restoration strategies (Total Seedling Planting (PAT), Diversity Islands (ID) and Direct Seeding (SD)) of the forest vegetation associated with watercourses was analyzed. It were evaluated: the number of individuals, resprouting intensity, above-ground biomass, canopy area, average diameter and height, per individual, in 58 sample units (10 x 30 m) distributed among the strategies after 2.5 years of implantation. It was also evaluated the main species and their similarities between the strategies. The SD provided more effective as the number of individuals, biomass and treetop area, while the intensity of resprouting was higher in ID and there were no differences in mean height and diameter. Each strategy presented a particular set of most successful species and the most similar were those that used seedlings (PAT and ID). The highlight of the SD strategy is magnified when considering ecological perspectives, and social costs involved. The species contributed to the differentiation of strategies, because they provide distinct ecological functions that influence ecological processes at the community level and individuals. Keywords: forest restoration; nucleation; direct seeding; seedling planting; Amazon rainforest.