El árbol Acacia mangium (Fabaceae) facilita la recuperación de áreas mineras en la selva lluviosa del Chocó, Colombia

Introducción: Las áreas impactadas por minería en bosques tropicales requieren de la aplicación de estrategias de restauración ecológica, pero este proceso, muchas veces involucra el uso de especies vegetales exóticas, desconociendo los efectos sobre la regeneración ecológica de los sitios donde se introducen. Objetivo: Evaluar el efecto de las plantaciones de Acacia mangium (planta exótica) sobre la rehabilitación ecológica temprana (suelo y vegetación) de áreas impactadas por minería de oro a cielo abierto en la selva pluvial tropical del Chocó, Colombia. Métodos: Se seleccionaron 16 áreas mineras como unidades de muestreo (ocho reforestadas con A. mangium y ocho en sucesión natural) en dos localidades. En cada unidad de muestreo se estableció una parcela de 2 × 50 m (cuatro parcelas por escenario de muestreo y localidad), donde se analizó la fertilidad del suelo (parámetros físicos y químicos) y se cuantificó el número de individuos de cada especie de planta vascular. Resultados: Se registraron 73 especies (69 géneros, 45 familias). La densidad de individuos fue mayor en áreas de sucesión natural que en aquellas reforestadas con A. mangium; por el contrario, la riqueza y diversidad de especies fueron superiores bajo las plantaciones de A. mangium. La similitud florística fue baja entre escenarios sucesionales (especies compartidas 35.6 %). El suelo mostró mejores condiciones (especialmente, N-NHO3) en áreas con A. mangium que en áreas en regeneración natural. Conclusiones: Las plantaciones de A. mangium parecen facilitar la rehabilitación temprana de la fertilidad del suelo y la vegetación en las minas abandonadas; por lo tanto, esta especie puede jugar un papel importante para la implementación de estrategias de restauración ecológica de áreas impactadas por minería de oro a cielo abierto en el Chocó y otros sistemas forestales tropicales con condiciones ambientales y de perturbación similares.

Introduction: Mining-impacted areas in tropical forests require the application of ecological restoration strategies, but this process often involves use of exotic plant species ignoring the effects on the ecological regeneration of the sites where they are introduced. Objective: To evaluate the effect of Acacia mangium plantations (exotic plant) on early ecological rehabilitation (soil and vegetation) of areas impacted by open-pit gold mining in the tropical rain forest of Chocó, Colombia. Methods: 16 mining areas were selected as sampling units (eight reforested with A. mangium and eight in natural succession) in two locations. In each sampling unit, a 2 × 50 m plot was established (four plots per sampling scenario and locality), where soil fertility (physical and chemical parameters) was analyzed and the number of individuals of each vascular plant species was quantified. Results: 73 species (69 genera, 45 families) were recorded. The density of individuals was higher in areas of natural succession than in those reforested with A. mangium; conversely, species richness and diversity were higher under the A. mangium plantations. Floristic similarity was low between successional scenarios (shared species 35.6 %). The soil showed better conditions (especially N-NHO3) in mining areas with A. mangium than in those in natural regeneration. Conclusions: A. mangium plantations appears to facilitate the early rehabilitation of soil fertility and vegetation in abandoned mines; therefore, this species can play an important role in the implementation of ecological restoration strategies in areas impacted by open-pit gold mining in the Chocó and other tropical forest systems with similar environmental and disturbance conditions.

Overcoming dormancy of Senna multijuga seeds with an ultrasonic probe the comparison with ultrasound and sulfuric acid baths / Superação da dormência de sementes de Senna multijuga com sonda ultrassônica e a comparação com banho de ultrassom e ácido sulfúrico

ABSTRACT: Understanding germination is extremely important for the production of seedlings that are used in revegetation of degraded areas. Some species enter dormancy as a survival strategy to overcome adverse environmental conditions. Their seeds germinate only when this process is interrupted, which can occur naturally when the conditions become more favorable for the survival of the species or by induction. Studies showed that ultrasound can increase the germination rate of seeds. The objective of this research was to evaluate the effect of an ultrasound probe and compare it with other methodologies implemented for seed germination of Senna multijuga (Rich.) H. S. Irwin & Barneby, a species used in revegetation of degraded areas. The experiment evaluated the effect of the ultrasonic probe at different powers on seeds that were placed to germinate in a gerbox on paper moistened with distilled water. Ninety-five percent of seeds treated with ultrasound and only 14% of non-treated seeds (control) germinated. There was no significant difference in the germination among the treatments with different powers. The speed of germination index (SGI) reached 4.7 in seeds that underwent the treatment, and 0.6 in the control group. From the results it is possible to conclude that the ultrasound probe is an efficient treatment to accelerate seed germination in this species; and consequently, contributed to production of a greater number of seedlings to be used in revegetation of degraded areas in a short period of time.

RESUMO: Entender a germinação é extremamente importante para produção de mudas utilizadas na revegetação de áreas degradadas. Algumas espécies são consideradas dormentes por apresentarem uma estratégia de sobrevivência para superar condições ambientais adversas. Essas sementes germinam apenas quando esse processo é interrompido, o que pode ocorrer naturalmente quando as condições se tornam mais favoráveis para a sobrevivência da espécie ou de forma induzida. Estudos demonstram que o ultrassom pode aumentar a taxa de germinação das sementes. Esse trabalho teve como objetivo avaliar o efeito da sonda ultrassom e compará-la com outras metodologias utilizadas para a germinação de sementes de Senna multijuga (Rich.) H. S. Irwin & Barneby, espécie utilizada na revegetação de áreas degradadas. O experimento avaliou o efeito da sonda de ultrassom em diferentes potências sobre as sementes, que foram colocadas para germinar em gerbox sobre papel umedecido com água destilada. Das sementes que sofreram o tratamento com a sonda de ultrassom 95% germinaram, já das que não sofreram nenhum tratamento apenas 14% delas germinaram. Não houve diferença significativa entre as diferentes potências avaliadas. O índice de velocidade de germinação (IVG) chegou a 4,7 em sementes que sofreram o tratamento e 0,6 no grupo controle. A partir dos resultados é possível concluir que a sonda de ultrassom é um tratamento eficiente para acelerar a germinação de sementes desta espécie e, consequentemente, contribuir para produção de um maior número de mudas em curto período para serem utilizadas na revegetação de áreas degradadas.

Formación del banco de semillas durante la revegetación temprana de áreas afectadas por la minería en un bosque pluvial tropical del Chocó, Colombia / Soil seed bank formation during early revegetation of areas affected by mining in a tropical rain forest of Chocó, Colombia

ResumenLa minería es una de las principales actividades económicas en muchas regiones tropicales y también es la causa de la devastación de amplias superficies de bosques tropicales naturales. El conocimiento del potencial regenerativo de las áreas alteradas por minería es vital para la restauración ecológica de estas áreas críticas. El objetivo del presente trabajo fue evaluar el efecto de la edad de abandono de las minas y su distancia al bosque adyacente sobre la formación del banco de semillas del suelo en minas abandonadas en el San Juan, Chocó, Colombia. Para ello, se determinó la abundancia y composición de especies del banco de semillas, así como la dinámica de la lluvia de semillas, en minas de distinta edad (6 y 15 años), tras el cese de la actividad minera, y distancia a la matriz del bosque adyacente (50 y 100 m). La lluvia de semillas estuvo compuesta por cinco especies de plantas, todas de dispersión anemócora, y fue mayor en la mina de 6 años que en la de 15. No hubo diferencias significativas en la cantidad de semillas recolectadas a 50 m y 100 m de distancia del bosque adyacente. El banco de semillas estuvo representado por ocho especies: dos de dispersión anemócora (comunes a la lluvia de semillas) y el resto de dispersión zoócora. La abundancia de semillas en el suelo no varió con la edad de la mina, pero fue mayor a distancias próximas al bosque que alejadas de este. Durante la regeneración temprana, la formación del banco de semillas en el seno de las minas parece estar relacionada con la cercanía a otras áreas alteradas más que con su proximidad al bosque adyacente o la edad de las minas. Al respecto, el establecimiento de perchas artificiales o conservación de árboles remanentes en el seno de las minas podrían promover la entrada de semillas dispersadas por aves. No obstante, dado que el banco de semillas del suelo puede verse afectado por la alta precipitación de la zona, se recomienda promover estudios que valoren medidas encaminadas a favorecer la formación del banco de semillas del suelo de las minas en ambientes de alta pluviosidad como en la región del Chocó.

Abstract:Mining is one of the main economic activities in many tropical regions and is the cause of devastation of large areas of natural tropical forests. The knowledge of the regenerative potential of mining disturbed areas provides valuable information for their ecological restoration. The aim of this study was to evaluate the effect of age of abandonment of mines and their distance from the adjacent forest, on the formation of soil seed bank in abandoned mines in the San Juan, Chocó, Colombia. To do this, we determined the abundance and species composition of the soil seed bank, and the dynamics of seed rain in mines of different cessation period of mining activity (6 and 15 years), and at different distances from the adjacent forest matrix (50 and 100 m). Seed rain was composed by five species of plants with anemocorous dispersion, and was more abundant in the mine of 6 years than in the mine of 15 years. There were no significant differences in the number of seeds collected at 50 m and 100 m from the adjacent forest. The soil seed bank was represented by eight species: two with anemocorous dispersion (common among the seed rain species) and the rest with zoochorous dispersion. The abundance of seeds in the soil did not vary with the age of the mine, but was higher at close distances to the forest edge than far away. During the early revegetation, the formation of the soil seed bank in the mines seems to be related to their proximity to other disturbed areas, rather than their proximity to the adjacent forest or the cessation activity period of mines. Therefore, the establishment of artificial perches or the maintenance of isolated trees in the abandoned mines could favour the arrival of bird-dispersed seeds at mines. However, since the soil seed bank can be significantly affected by the high rainfall in the study area, more studies are needed to evaluate management actions to encourage soil seed bank formation in mines of high-rainfall environments in the Chocó region. Rev. Biol. Trop. 65 (1): 393-404. Epub 2017 March 01.

Enrichment of arbuscular mycorrhizal fungi in a contaminated soil after rehabilitation

Abstract Spore counts, species composition and richness of arbuscular mycorrhizal fungi, and soil glomalin contents were evaluated in a soil contaminated with Zn, Cu, Cd and Pb after rehabilitation by partial replacement of the contaminated soil with non-contaminated soil, and by Eucalyptus camaldulensis planting with and without Brachiaria decumbens sowing. These rehabilitation procedures were compared with soils from contaminated non-rehabilitated area and non-contaminated adjacent soils. Arbuscular mycorrhizal fungi communities attributes were assessed by direct field sampling, trap culture technique, and by glomalin contents estimate. Arbuscular mycorrhizal fungi was markedly favored by rehabilitation, and a total of 15 arbuscular mycorrhizal fungi morphotypes were detected in the studied area. Species from the Glomus and Acaulospora genera were the most common mycorrhizal fungi. Number of spores was increased by as much as 300-fold, and species richness almost doubled in areas rehabilitated by planting Eucalyptus in rows and sowing B. decumbens in inter-rows. Contents of heavy metals in the soil were negatively correlated with both species richness and glomalin contents. Introduction of B. decumbens together with Eucalyptus causes enrichment of arbuscular mycorrhizal fungi species and a more balanced community of arbuscular mycorrhizal fungi spores in contaminated soil.

Growth of tropical tree species and absorption of copper in soil artificially contaminated

Abstract Reclamation of copper contaminated sites using forest species may be an efficient alternative to reduce the negative impact. The aim of this study was to quantify the growth and evaluate the quality of seedlings of native species at different doses of copper in the soil. The experimental design was completely randomized, with seven replications in a factorial arrangement (3×9), using three indigenous species of plants (Anadenanthera macrocarpa, Mimosa scabrella and Apuleia leiocarpa) and nine doses of copper in the soil (0, 60, 120, 180, 240, 300, 360, 420 and 480 mg kg1).The experiment was carried out in a greenhouse which the seedlings were grown for 180 days. The experimental units were plastic pots of 125 cm3 filled with Oxisol. The results indicated that the levels of copper applied to the soil decreased the quality of seedlings and growth of Apuleia leiocarpato a lesser extent compared with Mimosa scabrella and Anadenanthera macrocarpa. Anadenanthera macrocarpa was the forest species that resulted in the lowest copper translocation from roots to shoots. In addition, the Apuleia leiocarpa exhibited high resistance and tolerance for copper in the soil and also, it is highlighted an ability for copper phytoremediation.

Resumo A recuperação de áreas contaminadas com cobre utilizando espécies florestais pode ser uma alternativa eficiente para reduzir o impacto negativo deste elemento nestas áreas. O objetivo deste estudo foi quantificar o crescimento e avaliar a qualidade de mudas de espécies nativas em diferentes doses de cobre no solo. O delineamento experimental foi inteiramente casualizado, com sete repetições, em um esquema fatorial (3×9), utilizando-se três espécies nativas de plantas (Anadenanthera macrocarpa, Mimosa scabrella e Apuleia leiocarpa) e nove doses de cobre no solo (0, 60, 120, 180, 240, 300, 360, 420 e 480 mg kg1). O experimento foi realizado em casa de vegetação, onde as plantas foram cultivadas por 180 dias. As unidades experimentais foram vasos de plástico de 125 cm3, preenchidos com Latossolo Vermelho distrófico. Os resultados indicaram que o nível de cobre aplicado ao solo reduziu a qualidade de plântulas e crescimento de Apuleia leiocarpa para um menor grau comparado com bracatinga e angico. Anadenanthera macrocarpa foi a espécie florestal que apresentou menor translocação de cobre a parte aérea das mudas. Além disso, a Apuleia leiocarpa exibiu elevada tolerância para o cobre no solo e também destaca-se mostrando uma capacidade para fitoremediação de áreas contaminadas com cobre.

Growth of tropical tree species and absorption of copper in soil artificially contaminated / Crescimento de espécies arbóreas tropicais e absorção de cobre em solo artificialmente contaminado

Abstract Reclamation of copper contaminated sites using forest species may be an efficient alternative to reduce the negative impact. The aim of this study was to quantify the growth and evaluate the quality of seedlings of native species at different doses of copper in the soil. The experimental design was completely randomized, with seven replications in a factorial arrangement (3×9), using three indigenous species of plants (Anadenanthera macrocarpa, Mimosa scabrella and Apuleia leiocarpa) and nine doses of copper in the soil (0, 60, 120, 180, 240, 300, 360, 420 and 480 mg kg–1).The experiment was carried out in a greenhouse which the seedlings were grown for 180 days. The experimental units were plastic pots of 125 cm3 filled with Oxisol. The results indicated that the levels of copper applied to the soil decreased the quality of seedlings and growth of Apuleia leiocarpato a lesser extent compared with Mimosa scabrella and Anadenanthera macrocarpa. Anadenanthera macrocarpa was the forest species that resulted in the lowest copper translocation from roots to shoots. In addition, the Apuleia leiocarpa exhibited high resistance and tolerance for copper in the soil and also, it is highlighted an ability for copper phytoremediation.

Resumo A recuperação de áreas contaminadas com cobre utilizando espécies florestais pode ser uma alternativa eficiente para reduzir o impacto negativo deste elemento nestas áreas. O objetivo deste estudo foi quantificar o crescimento e avaliar a qualidade de mudas de espécies nativas em diferentes doses de cobre no solo. O delineamento experimental foi inteiramente casualizado, com sete repetições, em um esquema fatorial (3×9), utilizando-se três espécies nativas de plantas (Anadenanthera macrocarpa, Mimosa scabrella e Apuleia leiocarpa) e nove doses de cobre no solo (0, 60, 120, 180, 240, 300, 360, 420 e 480 mg kg–1). O experimento foi realizado em casa de vegetação, onde as plantas foram cultivadas por 180 dias. As unidades experimentais foram vasos de plástico de 125 cm3, preenchidos com Latossolo Vermelho distrófico. Os resultados indicaram que o nível de cobre aplicado ao solo reduziu a qualidade de plântulas e crescimento de Apuleia leiocarpa para um menor grau comparado com bracatinga e angico. Anadenanthera macrocarpa foi a espécie florestal que apresentou menor translocação de cobre a parte aérea das mudas. Além disso, a Apuleia leiocarpa exibiu elevada tolerância para o cobre no solo e também destaca-se mostrando uma capacidade para fitoremediação de áreas contaminadas com cobre.

Floristic woody composition of revegetated mining sites in the Brazilian Federal District / Composição florística lenhosa de jazidas revegetadas no Distrito Federal

The extension degraded by mining in the Brazilian Federal District - BFD is proportionately five times larger than country's average. The restoration of plant communities at these sites is ecologically necessary and legally compulsory. Native woody species are commonly used for ecosystem restoration and this study aimed to identify the floristic composition of woody species introduced in BDF mining sites and discuss its outcomes. The floristic survey was conducted by sampling groups of one hundred individuals until sampling sufficiency was achieved. In total 4,500 plants were sampled in ten sites, which housed 92 autochthonous and 21 allochthonous woody species. Plant communities in the sites assembled between 13 and 62 species, planted at low density - 467 ± 222 plants ha-1. The preferential use of autochthonous species in the revegetation projects resembles the standards recommended by successional restoration models, but the floristic diversity and plant density in initial communities fall below the values deemed as ideal. The 92 autochthonous species include representatives of various habitats, ecological groups and dispersal syndromes. These 92 species currently in use may be regrouped in initial plant communities denser and more diverse than those found in the revegetated sites. The surveyed plant communities were massively composed of arboreal species and such pattern may drive succession towards the formation of forest ecosystems where previously inhabited savanna formations.

A extensão minerada no Distrito Federal - DF é proporcionalmente cinco vezes superior à média nacional. A restauração das comunidades vegetais nesses locais é necessária e obrigatória, e o plantio de espécies lenhosas é prática comum de restauração. Dessa forma, este trabalho visou identificar e avaliar a composição florística lenhosa introduzida em jazidas mineradas no DF como meio de restaurar o ecossistema natural. O levantamento florístico nas áreas selecionadas foi realizado por meio da amostragem de grupos de cem indivíduos, até se obter suficiência amostral. Foram amostradas 4.500 plantas em dez jazidas, que abrigavam 92 espécies lenhosas autóctones e 21 alóctones. As comunidades vegetais levantadas eram formadas por 13 a 62 espécies, plantadas a uma baixa densidade - 467 ± 222 plantas ha-1. O uso preferencial de espécies autóctones nos projetos de revegetação os assemelham aos padrões recomendados pelos modelos sucessionais de restauração, mas a diversidade florística e densidade de plantas nas comunidades iniciais estão abaixo dos valores considerados ideais. Entre as 92 espécies identificadas há representantes de variados habitats, grupos ecológicos e síndromes de dispersão. Portanto, essas 92 espécies podem ser reagrupadas em comunidades iniciais mais densas e diversas do que as verificadas nos projetos executados. As comunidades vegetais nos locais investigados eram predominantemente compostas por espécies arbóreas e tal padrão pode levar à formação de ecossistemas florestais onde antes havia formações savanânicas.

Management of the environmental restoration of degraded areas

The aim of this work was to study ecotechnology for the management of degraded areas originally covered by the Atlantic Rainforest and located at the coordinates 25º31'50''S, 9º09'30''W. The area included 12 islands, each consisting of six jute bags with 20 kg of substrate (cattle manure and soil transposed from forest fragments). In six of these bags, native plants and seeds were also included. Six additional islands were selected randomly in the vicinity as the control. The process of evaluation was monitored through the chemical and granulometric soil analysis and surveys of survival, biometrics, floristic and phytosociological vegetation. An improvement in soil properties was observed where the model was implemented, which could be attributed to the substrate and re-vegetation. In the floristic and phytosociological studies, out of the 118 identified species, 65 were observed in the first floristic inventory and 86 in the second floristic inventory with similarities between the subfields of 27.69% and 11.36%, respectively. The influence of the substrate seed bank in the implemented islands was also observed. Increased diversity was only significant in the subareas with the model. It was concluded that this technology was effective in accelerating the succession and promoting the beginning of the restoration.

Desenvolvimento do Pinus elliottii e do Eucalyptus tereticornis consorciado com plantas de cobertura, em solos degradados por arenização / Growth of Pinus elliottii and Eucalyptus tereticornis associated with cover plants, in degraded soils by arenization

Espécies florestais exóticas têm sido utilizadas para a recuperação de solos degradados, auxiliando no controle da erosão hídrica e eólica. No sudoeste do Rio Grande do Sul, foram testados o Pinus elliotii Engelm. e o Eucalyptus tereticornis Sm., com o objetivo de avaliar o crescimento destas espécies e testar sua capacidade na contenção do fenômeno da arenização. Os tratamentos consistiram do plantio das duas espécies sobre o solo degradado por arenização (SD), sobre o campo nativo (C), sobre o campo nativo associado a plantas de cobertura (C + PC) e sobre o solo degradado com plantas de cobertura (SD + PC). Como plantas de cobertura, foram testadas a aveia preta (Avena strigosa Schieb.) e um tremoço nativo do ecossistema dos campos sulinos, o Lupinus albescens H. et Arn.. Determinaram-se o percentual de sobrevivência inicial, a altura, o diâmetro à altura do colo (DAC) e o fator de produtividade (FP) das espécies florestais, aos 30 dias, seis meses e 12 meses após plantio. O experimento foi conduzido em delineamento inteiramente casualizado, e os resultados submetidos ao teste de Duncan, em um nível de 5 por cento de probabilidade de erro. Em relação à sobrevivência inicial, apenas o pínus apresentou diferenças estatísticas, com menor percentual no tratamento C+PC. Os resultados demonstraram que o eucalipto beneficiou-se do consórcio com plantas de cobertura, enquanto o pínus apresentou maior sensibilidade à competição interespecífica.

Exotic forest species have been used for soil reclamation, as well as helping in the control of water and wind erosion. In the southwest of Rio Grande do Sul state, Brazil, the Pinus elliotii Engelm. and the Eucalyptus tereticornis Sm., were tested with the objective of evaluating the growth of these species and testing its capacity for reducing the arenization process. The treatments consisted of planting the two species on the degraded soil by arenization (DS), on the native grassfield (C), on the native grassfield associated with cover crops (C + PC) and on the degraded soil associated with cover crops (DS + PC). As cover crops were tested the black oat (Avena strigosa Schieb.) and a Lupinus native from the southern grassfields ecosystem, the Lupinus albescens H. et Arn.. The plants survival rate, height, basal diameter and the productivity factor of the forest species were obtained in the thirty days, six months and twelve months after planting. The experiment was conduced in completely randomized design, and results submited to Duncan test, in level of 5 percent error probability. In relation to initial survival, only pine presented significative differences, with lesser percentual in the treatment C+PC. Results showed that Eucalyptus benefited from the consortium with cover crops, while pine presented greater sensibility to interespecific competition.