ABSTRACT
Abstract Edaphic macrofauna must be better studied if we want to take advantage of their full potential for the restoration of tropical ecosystems. We investigated changes in edaphic macrofauna density and diversity along a secondary succession chronosequence in the Atlantic Forest. Our results show some clear patterns of change in soil macrofauna along the chronosequence. Density did not increase along secondary succession, but was correlated with canopy cover. Diversity was characterized by high dominance of social insects and evenness among other groups. We conclude soil macrofauna has a high capacity to recolonize young forests and that its recovery is considerably fast compared to other ecosystem transformations.
Resumo A macrofauna edáfica deve ser mais bem estudada se quisermos aproveitar todo o seu potencial para a restauração de ecossistemas tropicais. Nós investigamos as mudanças de densidade e diversidade da macrofauna edáfica em uma cronossequência durante a sucessão secundária na Mata Atlântica. Nossos resultados mostram padrões claros de mudança. A densidade não aumentou ao longo da sucessão secundária, mas foi correlacionada com a cobertura de dossel. A diversidade foi caracterizada pela alta dominância de insetos sociais e equidade entre os demais grupos. Nós concluímos que a macrofauna edáfica tem alta capacidade de recolonizar florestas jovens e que sua recuperação é relativamente rápida se comparada a outras transformações ecossistêmicas.
Subject(s)
Animals , Soil Microbiology/standards , Trees/growth & development , Adaptation, Physiological , Forests , Conservation of Natural Resources , Environmental Restoration and Remediation , Soil/chemistry , Tropical Climate , Brazil , Ecosystem , BiodiversityABSTRACT
Two field experiments were carried out at an organic farm [Minoufia Governorate] during 2005- 2006 and 2006-2007 seasons to study the interaction effect of biofertilization and organic manuring on dehydrogenase, polyphenol oxidase and peroxidase activity, macronutrients uptake, oil yield and oil composition of marjoram. Greater activities of dehydrogenase, peroxidase and polyphenol oxidase were obtained in soil and marjoram treated with combination of biofertilizers and organic manure than soil treated with biofertilizers or organic manure. The greatest activities of peroxidase and polyphenol oxidase were obtained with the treatment of biofertilization combined with full dose of organic manure. Similar results trend was observed with N, P and K uptake because N, P and K uptake by marjoram were greater with dual application of biofertilization and organic manure than other treatments. There is no significant difference between oil yield obtained with chemical fertilization treatment and biofertilizers combined with full dose of organic manure treatment. Fourteen compounds, accounting for more than 97% of the total volatiles components in most marjoram samples were detected and identified. Dual application of organic manure and biofertilization to soil and marjoram produced maximum percent of terpincn-4-ol [the major compound in marjoram oil] compound in marjoram
Subject(s)
Manure , Origanum/genetics , Soil Microbiology/standardsABSTRACT
Communities of Actynomicetes fungy in three vegetation types of the Colombian Amazon: abundance, morphotypes and the 16s rDNA gene. Among soil microorganisms, Actinomycetes play an important role in the sustainability of natural and agricultural systems: decomposition of organic matter; degradation of recalcitrant compounds like lignin; nitrogen fixation; degradation of agricultural chemicals and biological control in plants and animals. We evaluated their diversity in soils under three different vegetation covers (pasture, tropical primary forest and stubble) at two depths in the Southern Colombian Amazon border. We collected five replicates per vegetation type (in each, three samples at 0-20cm and three at 20-30cm; for a total of 30 samples). Abundance and phenotypic diversity were determined by plate counting. Genomic DNA was extracted from the isolates: the 16s rDNA gene was amplified with specific primers, and its genetic diversity was estimated by means of an amplified restriction analysis (ARDRA). Actynomicetes abundance varied with vegetation and depth, possibly reflecting presence of earthworms, macro-fauna and physico-chemical characteristics associated to fertility, as well as organic matter, total bases, and optimal capacity to cationic interchange. Primary forests had the highest diversity. Sixteen morpho-types (six genera) were identified; Streptomyces was the most abundant everywhere. The heterogeneity of ARDRA patterns prevented species identification because of the intra-species variability in sequences of 16s rDNA operons. This community is a biological indicator of landscape alteration and could include new bio-active compounds of pharmaceutical interest. Rev. Biol. Trop. 57 (4): 1119-1139. Epub 2009 December 01.
Los actinomicetos son importantes en la sostenibilidad de sistemas naturales. Su diversidad fue evaluada en suelos de bosque, pastizal y rastrojo, y dos profundidades en el Sur del Trapecio Amazónico Colombiano. Se analizaron suelos de cinco repeticiones por cobertura para un total de 15 unidades. Se tomaron seis muestras en cada unidad y dos profundidades, para un total de 30. Los actinomicetos cultivables se determinaron por recuento en placa, se extrajo ADN, se amplificó el gen ADNr 16s y su diversidad genética se estimó por ARDRA. Hubo diferencias de abundancia entre coberturas y profundidades, relacionadas con la vegetación, presencia de lombrices, macrofauna, altos niveles de materia orgánica, y bases totales. Se obtuvieron valores de diversidad fenotípica similares para las tres coberturas, pero los bosques son más diversos. Se identificaron 16 morfotipos, agrupados en séis géneros, siendo Streptomyces el más abundante. La heterogeneidad de los patrones ARDRA no permitió la asignación de especies, reflejándose variaciones en las secuencias de diferentes operones ADNr 16s en un mismo organismo. Las perturbaciones en la cobertura influyen sobre los actinomicetos, generando cambios en su abundancia y diversidad. Su importancia ecológica permite proponerlos como indicadores biológicos de alteración del paisaje.
Subject(s)
Actinobacteria/genetics , DNA, Ribosomal/genetics , Poaceae/microbiology , /genetics , Soil Microbiology/standards , Trees/microbiology , Actinobacteria/classification , Actinobacteria/isolation & purification , Colombia , Genetic Variation , PhenotypeABSTRACT
New and exciting molecular methods, many using the 16S small sub-unit ribosomal nucleic acid molecule, are opening the microbial "black box" in soil. These studies have added much to our knowlodge of microbial diversity in soils, and are beginning to advance our understanding of the relationship between this diversity and its function in soil processes. Over the next few years, the knowlodge gained from molecular studies will, we hope, lead to improvements in sustainable land management and sustainable exploitation of soil genetic resources. As we enter the third millenium, it is appropriate to review the application of 16S rDNA methods to soil microbiology. This review examines 16S ribosomal DNA (rDNA) methods and their application to soil. It mentions their limits and suggests how they may be applied in the future.
Subject(s)
DNA/analysis , Ecology , RNA/analysis , Soil Microbiology/standards , Genetics, Microbial/methods , Genetic Techniques/standardsABSTRACT
Se estudió la interacción entre hongos vam nativos de suelos agrícolas de la provincia de Buenos Aires (Argentina), Glomus epigaeus y Bradyrhizobium japonicum en plantas de soja. La inoculación tripartita: vam nativas, G. epigaeus y B. japonicum produjeron plantas más vigorosas, con mayor número de nódulos y de mayor tamaño en relación a plantas no inoculadas. El contenido de nitrogeno en la porción aérea de las plantas aumentó un 102 porciento y el del fósforo un 233 porciento en plantas con inoculación tripartita, en relación al testigo no inoculado