Organic matter composition and paleoclimatic changes in tropical mountain peatlands currently under grasslands and forest clusters

Tropical peatlands are important ecosystems for Planet Earth, as they store large amounts of carbon and water. A better understanding of the impact of vegetation type and altitude in content, composition, and rate of accu mulation of organic matter is key for assessing the current role of such environments. This study evaluated fibric and soluble fractions as well as the lignocellulosic and the isotopic compositions of the peat organic matter from four tropical mountain peatlands located at different altitudes of the Serra do Espinhaço Meridional, state of Minas Gerais, Brazil. The peatlands are currently under grasslands and forest clusters. Samples of peat under both vegetation types were collected and analyzed for organic matter fractions, cellulose, and lignin (van Soest method), as well as carbon and nitrogen isotopes. Different depths were chosen for radiocarbon dating of se lected samples. The organic matter of peatlands currently under grasslands and forest clusters presented dif ferences in soluble fractions, lignocellulosic composition, and δ13C values. Multivariate analyses allowed grouping the peatlands by altitude and vegetation type. The chronological succession of grassland and forest clusters in tropical mountain peatlands was influenced by altitude and was related to paleoclimatic changes.info:eu-repo/semantics/publishedVersio

Hydrology and carbon flow in mountain tropical peatlands

?rea de concentra??o: Produ??o Vegetal.O presente trabalho foi realizado com apoio da Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG) (Processos CAG ? APQ ? 01614-14 e CAG - PPM - 00568-16).O presente trabalho foi realizado com apoio da Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - Brasil (CAPES) - C?digo de Financiamento 001.Turfeiras s?o ecossistemas formados pela acumula??o de tecidos vegetais em ambientes com condi??es anaer?bicas. Suas principais caracter?sticas definidoras s?o o solo org?nico e a reten??o de ?gua. S?o as propriedades hidrol?gicas das turfeiras que permitem a sua exist?ncia continuada. Entender a hidrologia das turfeiras ? fundamental para estes ecossistemas, j? que ? provavelmente a condi??o mais importante relacionada ? ecologia, ao desenvolvimento, ?s fun??es e aos seus processos de forma??o. O objetivo deste estudo foi avaliar o comportamento hidrol?gico e o fluxo de carbono em turfeiras tropicais de montanha e a influ?ncia da antropiza??o nestes ecossistemas. Foram instalados sete medidores de n?vel em duas turfeiras situadas no Chapad?o do Couto (MG), com intervalo de registro de trinta minutos, sendo quatro em turfeira protegida pelo Parque Estadual do Rio Preto e tr?s em uma turfeira antropizada do alto curso do rio Ara?ua?, utilizada para pastejo animal e que sofre queimadas frequentes. Tamb?m foram coletadas, a cada dois meses, amostras de ?gua em tr?s pontos em cada turfeira, nas quais foram analisados: S?lidos sol?veis totais; Potencial de oxidorredu??o; temperatura; pH; oxig?nio dissolvido; condutividade el?trica; demanda qu?mica de oxig?nio; turbidez; cloro total; f?sforo; pot?ssio; ferro total; Alum?nio; nitrato; am?nia e carbono org?nico total. No exut?rio da ?rea de recarga h?drica de cada turfeira foi medida a vaz?o, tamb?m a cada dois meses. Par?metros clim?ticos da ?rea dos estudos foram obtidos com instala??o de uma esta??o meteorol?gica com registros tomados a cada hora. Com os dados obtidos pelos medidores de n?vel foram calculados a amplitude de varia??o e varia??o do len?ol fre?tico. Tamb?m foi calculado o rendimento espec?fico para as turfeiras estudas, relacionando a precipita??o e a varia??o na eleva??o do len?ol fre?tico. Os dados foram analisados por fatorial/componente principal para se obter os principais processos influenciadores da qualidade da ?gua em cada turfeira. Os valores de rendimento especifico foram correlacionados com a vaz?o em cada turfeira. Tamb?m foi usada regress?o m?ltipla para obter uma equa??o que melhor representasse a vaz?o em cada ?rea. A estat?stica multivariada permitiu a identifica??o de processos que influenciam a qualidade da ?gua, sendo que em ?reas protegidas, o principal processo influenciador da qualidade das ?guas de suas turfeiras ? a decomposi??o da mat?ria org?nica e as turfeiras em ?reas sem prote??o a qualidade da ?gua ? influenciada pela eros?o da ?rea de recarga. A prote??o das turfeiras ainda reduz a varia??o do len?ol fre?tico, al?m de torna-las mais produtivas, em rela??o a quantidade de ?gua por unidade de ?rea e protege sua capacidade de reten??o de ?gua dos efeitos antr?picos, principalmente inc?ndios. Turfeiras tropicais de montanha s?o bastante sens?veis a antropiza??o, que provoca redu??o do estoque de carbono, diminui??o do volume de ?gua armazenado e degrada??o da qualidade de suas ?guas. Desta forma, a preserva??o ? de fundamental import?ncia para estes ecossistemas.Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Tese (Doutorado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2018.Peatlands are ecosystems formed by the accumulation of litter in environments with anaerobic conditions. Its main defining characteristics are organic soil and water retention. Therefore, it is the hydrological properties of peatlands that allow its continued existence. Understand the hydrology of peatlands is critical to these ecosystems, since it is probably the most important condition related to ecology, development, functions and their formation processes. The aim of this study was to evaluate the hydrological process and the dynamic of carbon in a mountain tropical peatlands and the influence of anthropization on these ecosystems. Seven level meters were installed in two peatlands located in Chapad?o do Couto (MG), with a record interval of thirty minutes, four of which were in protected peatland by the State Park of Rio Preto and three in an anthropic peatland of the upper Ara?ua? River, used for animal grazing and suffering frequent burnings. Also, water samples were collected every two months at three points in each peatland, in which where analyzed: Total soluble solids; oxidoreduction potential; temperature; pH; dissolved oxygen; electric conductivity; chemical oxygen demand; turbidity; total chlorine; phosphor; potassium; total iron; Aluminum; nitrate; ammonia and total organic carbon. In the exutory area of the water recharge area of each peatland was measured, also every two months. Climatic parameters of the study area were obtained with the installation of a meteorological station with records taken every hour. With the data obtained by the piezometers were calculated the amplitude of variation and variation of the water table. It was also calculated the specific yield for the peatland studied, relating the precipitation and the variation in the elevation of the water table. The data were analyzed by factorial/component analysis to obtain the main processes influencing the water quality in each peatland. Multiple regression was also used to obtain an equation that best represents the flow in each area. Multivariate statistics allowed the identification of processes that influence water quality. In protected areas, the main process influencing the quality of the water in the peatlands is the decomposition of organic matter and the peatland in unprotected areas. influenced by the erosion of the recharge area. The protection of peatlands still reduces the variation of the water table, in addition to making them more productive, in relation to the amount of water per unit area and protects their capacity of water retention of anthropic effects, mainly fires. Mountain tropical peatlands are quite sensitive to anthropization, which causes carbon stock reduction, decreased volume of stored water, and degraded water quality. In this way, preservation is of fundamental importance for these ecosystems

Effects of sources and doses of humic acids in bean production (Phaseolus vulgaris L.)

A mat?ria org?nica (MOS) do solo consiste de uma mistura de compostos em v?rios est?gios de decomposi??o, resultante da degrada??o biol?gica de res?duos de plantas e animais, e da atividade de microrganismos, denominados subst?ncias h?micas (SHs). Essas subst?ncias fracionadas em ?cidos f?lvicos (AF), ?cidos h?micos (AH) e humina (H), de acordo com sua solubilidade em meio ?cido ou b?sico. Os AH t?m sido usados como fertilizantes aplicados diretamente no solo ou via foliar, principalmente por influenciarem o metabolismo das plantas. Objetivou-se com este trabalho avaliar em feijoeiro (Phaseolus vulgaris L.), a influ?ncia de fontes e doses diferentes de AH, na produ??o, crescimento radicular e absor??o de nutrientes e biodisponibilidade de nutrientes no solo. O experimento foi conduzido utilizando o delineamento em blocos casualizados com 15 tratamentos, sendo estes as fontes de AH (turfa - 1, composto - 2 e produto comercial - 3) e as doses de AH (0, 2, 8, 16 e 32 kg ha-1), com quatro repeti??es. Foram avaliadas: altura das plantas (cm), di?metro do caule (cm), teor de clorofila (?g cm-2) e teor de macro e micronutrientes nas folhas no florescimento do feijoeiro e ao fim do experimento, peso de sementes (g), massa seca da parte a?rea e de ra?zes (g), n?mero de vagem por planta e de sementes por vagem e no solo: pH em ?gua e teores de mat?ria org?nica, P, K, Ca, Mg, Al e H+Al. A aplica??o de AH reduziu o crescimento e produ??o de gr?o, com aumento das doses em cada fonte, seguindo a ordem fonte 3 > fonte 1 > fonte 2. Os teores de P, K, Cu, Fe, Mn e Zn nas folhas foram influenciados pelas doses de todas as fontes de AH. Houve redu??o para maioria dos nutrientes quantificados nas folhas com aumento das doses de AH. Os teores de P e K se elevaram no solo, com a aplica??o de AH. Para condi??es testadas, n?o se recomenda utiliza??o de AH para cultura do feijoeiro.Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (Capes)Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2015.The soil organic matter (SOM) consists of a mixture of compounds in many decomposition stages, the result of biological degradation of residues of plants and animals, and microorganisms activity, called humic substances (HS). These substances are fractionated into fulvic acids (FA), humic acids (HA) and humin (H), according to their solubility in acidic or basic medium. HA have been used as fertilizers directly applied to the soil or via foliar, mainly because they influence plants metabolism. The main goal of this study was evaluating, in bean plant (Phaseolus vulgaris L.), the influence of sources and different doses of HA in production, root growth, nutrients absorption and bioavailability of nutrients in the soil. The experiment was conducted using randomized block design with 15 treatments, which are the sources of HA (peat ? 1, compound ? 2 and commercial product ? 3) and doses of HA (0, 2, 8, 16 e 32 kg ha-1), with four repetitions. Evaluations were made on: plants height (cm), stem diameter (cm), chlorophyll content (?g cm-2) and content of macro and micronutrients in the leaves in the flowering stages and in the end of the experiment, seeds weight (g), dry matter of the aerial part and roots (g), number of pods per plant and seeds per pod, and in the soil: pH in water and contents of organic matter, P, K, Ca, Mg, Al and H+Al. Application of HA reduced bean growth and production, with increase of doses in each source, following order: source 3 > source 1 > source 2. Contents of P, K, Cu, Fe, Mn and Zn in the leaves were influenced by the doses of all HA sources. Most of the nutrients quantified in the leaves were reduced with increasing HA doses. Contents of P and K were increased in the soil with application of HA. For tested conditions, the use of HA for bean culture is not recommended

Natural and anthropogenic gamma-ray emitters and iron-bearing compounds distribution in peatlands of the southern Espinhaço mountain chain, Brazil

To help understand the dynamics of peatlands forming on the Southern Serra do Espinhaco, Brazil, the occurring natural (²²⁶Ra, ²³²Th, ⁴⁰K) and anthropogenic (¹³⁷Cs) activity of gamma-ray emitters located at three sites, namely the localities of Sao Joao da Chapada (CH), Pinheiro (PIN) and Pau de Fruta (PDF), was studied. The iron compounds were characterized by ⁵⁷Fe Mossbauer spectroscopy. Differences on natural radionuclide levels and distributions were found among the peatland sites, indicating differences on mineral composition, hydric regimes and living. Significant correlation was found only for ²³²Th–²²⁶Ra activity values (Pearson correlation coefficient of − 0.5), which is different from other South American soils, where significant positive correlations among all radionuclides were determined. In PDF and CH, the dose rate results are lower than the worldwide mean value, but in PIN, they are higher because of the relatively high ²²⁶Ra concentration. The only anthropogenic radionuclide is ¹³⁷Cs. The convection–diffusion model fits the CH and PDF activity profiles, although the PIN profile is likely affected by other soil mechanisms as well. Mossbauer spectra reveal Fe³⁺ in two different local environments and the occurrence of hematite in the upper samples of the CH site. The iron concentration decreases with depth. Contrary to soils of other regions, no significant correlation was found between iron species and the natural radioactivity. The studied peatlands exhibit clear differences between their natural and anthropogenic radionuclide distributions to those of mineral soils.Instituto de Física La PlataFacultad de Ingenierí

Chemical-Mineralogical Characterization of Magnetic Materials from Magnetic Soils of the Southern Espinhaço Mountain Chain and of the Upper Jequitinhonha Valley, State of Minas Gerais, Brazil

ABSTRACT In the Southern Espinhaço Mountain Chain and in the Upper Jequitinhonha Valley, magnetic soils, in different pedogenetic stages, are found to be forming over intrusions of basic lithology. The essential chemical and mineralogical properties of samples from magnetic soil profiles from those two physiographic environments in the state of Minas Gerais, Brazil, are reported. Three of the pedons (Rhodic Kandiustox – RKox, Rhodic Haplustox – RHox, and Typic Argiustoll - TAoll) were identified as being indeed developed over basic rocks; the fourth pedon (Typic Haplustox - THox) is currently forming on an acidic rock. Particle size and routine chemical analyses were performed on samples from all horizons of the four selected soil profiles. For a deeper insight into the dominant mineralogy of each diagnostic soil horizon, the elemental contents, expressed in terms of the corresponding metal cation oxides, namely Fe2O3, Al2O3, and MnO2, were obtained from digesting the whole soil samples with sulfuric acid. A similar chemical analytical procedure was performed for the residual solid extracts obtained from attacking the whole soil materials with mixtures of (i) dithionite - citrate - bicarbonate and (ii) oxalate - oxalic acid. The soil samples were also analyzed by Mössbauer spectroscopy at room temperature (~298 °K) in an attempt to better identify the main magnetic iron oxides. Maghemite (δFe2O3) was found in all samples and magnetite (Fe3O4) was identified only for the sample from the Typic Argiustoll. The pedogenetic loss of silica and consequent accumulation of iron and aluminum oxides along the profile are found to be somehow correlated to the weathering sequence in the soils forming on basic rocks: TAoll < RKox < RHox

Composição lignocelulósica e isótopica da vegetação e da matéria orgânica do solo de uma turfeira tropical: I - composição florística, fitomassa e acúmulo de carbono Lignocellulosic and isotopic composition of vegetation and soil organic matter of a tropical peat: I floristic composition, biomass and carbon stock

A matéria orgânica do solo (MOS) é um dos grandes reservatórios de carbono (C) da Terra e constitui um dos principais componentes do ciclo do C. Turfeiras, ambientes acumuladores de MOS, são produto da decomposição de vegetais, que se desenvolvem e se acumulam em ambientes saturados com água, sendo o estádio inicial da sequência de carbonificação. A fitomassa participa de forma marcante no ciclo global do C, armazenando em torno de 85 % de todo o C terrestre acima do solo. O tecido vegetal é composto principalmente por lignina, celulose e hemicelulose, constituindo até 85 % da biomassa seca. As plantas discriminam C de forma diferenciada, em razão de seu ciclo fotossintético (C3, C4 e CAM). As turfeiras da Serra do Espinhaço Meridional (SdEM-MG) são colonizadas por vegetação de Campo Limpo Úmido (CLU) e de Floresta Estacional Semidecidual (FES), onde ocorrem espécies dos ciclos fotossintéticos C3 e C4. Este trabalho objetivou avaliar a contribuição dessas duas fitofisionomias para o acúmulo de MOS, por meio da avaliação da fitomassa e da composição lignocelulósica e isotópica da vegetação e da MOS. A turfeira estudada localiza-se na SdEM e ocupa 81,75 ha. Para a estimativa da fitomassa do CLU e da FES, foram marcadas três parcelas de 0,5 x 0,5 m em cada fitofisionomia, onde todos os indivíduos da parcela foram cortados e armazenados. Para as análises isotópicas e lignocelulósicas da vegetação, identificaram-se as espécies dominantes em cada fitofisionomia. Amostras de solo foram coletadas em três locais representativos sob cada fitofisionomia, a cada 5 cm de profundidade, até 50 cm. Foram extraídas a celulose e a lignina das folhas das 15 espécies dominantes e das 60 amostras de turfeira para quantificação e determinação dos valores de &#948;13C e &#948;15N. Para datação da MOS, o 14C foi determinado em três profundidades, sob o CLU e a FES. A produção da fitomassa da FES foi muito superior à produção da do CLU. Os sinais isotópicos e a composição lignocelulósica da vegetação e da matéria orgânica do solo evidenciaram que a turfeira foi formada pela deposição de matéria orgânica da vegetação que a coloniza. O crescimento vertical e a taxa de acúmulo de C foram muito mais elevados sob a FES do que sob o CLU.<br>Soil organic matter (SOM) is one of the major reservoirs of carbon on Earth and is one of the key contributors to the carbon cycle. Peatlands are natural accumulators of organic matter commonly derived from decomposing plant residues in water-saturated environments, and represent an initial stage of a much longer pedogenic pathway leading to carbonification. The soil biomass markedly influences the global carbon cycle, accounting for approximately 85 % of all carbon on the Earth's surface. Plant tissues are mainly composed of lignin, cellulose and hemicelluloses, representing as much as 85 % of their dry biomass. Plants usually discriminate carbon differentially, according to their photosynthetic cycle (C3, C4 and CAM). The vegetation of the bogs in the southern domain of Serra do Espinhaço (SdEM; Brazil) consists mostly of moist grassland (CLU) and semideciduous forest (FES), with species of both C3 and C4 cycles. This study was designed to discriminate the contribution of these two vegetation types to the accumulation of soil organic matter by an analysis of the biomass and of the lignocellulosic and carbon isotopic composition and SOM. The studied peat is located in SdEM and covers an area of 81.75ha. Three 0.5x0.5m plots were marked per vegetation type, to delimit the sampling areas, for which biomass of CLU and FES were estimated. All plants per plot were cut and adequately stored to preserve as much of their fresh characteristics as possible. To characterize the isotopic and lignocellulosic composition of the vegetation, the species of each vegetation type were systematically identified according to their main botanic characteristics. Soil samples were collected at three representative sites under each vegetation type, at intervals of 5 cm, down to a depth of 50 cm. Cellulose and lignin were extracted from leaves of 15 dominant species and 60 peat samples, to quantify and determine the values of &#948;13C and &#948;15N. The 14C was determined at three depths under CLU and FES. The biomass production under FES was much higher than the biomass production under CLU. The isotopic signals and lignocellulosic composition of the vegetation and SOM confirmed that this peat was originated by the deposition of organic matter from the colonizing vegetation. The vertical growth and the carbon storage rates are much higher under FES than under CLU

Composição lignocelulósica e isótopica da vegetação e da matéria orgânica do solo de uma turfeira tropical: II - substâncias húmicas e processos de humificação Lignocellulosic and isotopic composition of vegetation and soil organic matter of a tropical peat: II humic substances and humification processes

Grande parte da matéria orgânica de Organossolos das turfeiras é composta por substâncias húmicas, formadas pela transformação de resíduos orgânicos pelos microrganismos do solo e pela polimerização dos compostos orgânicos em macromoléculas resistentes à degradação biológica. Os processos de humificação da matéria orgânica do solo (MOS) ainda são pouco compreendidos e o conhecimento sobre os precursores das substâncias húmicas é limitado, sendo apresentadas rotas diferentes para a formação dessas substâncias. Contudo, em todas as rotas, destaca-se a participação da lignina. Isótopos estáveis (13C, 15N) podem ser utilizados para rastrear processos de humificação da MOS, por meio da identificação de seus precursores. Este trabalho teve como objetivo avaliar comparativamente a composição isotópica da vegetação das fitofisionomias que colonizam uma turfeira tropical de altitude composta de Campo Limpo Úmido (CLU) e de Floresta Estacional Semidecidual (FES), em relação à composição isotópica das substâncias húmicas da MOS. A turfeira estudada ocupa 81,75 ha. Para as análises isotópicas e lignocelulósicas da vegetação, foram identificadas as espécies dominantes em cada fitofisionomia. Amostras de solo foram coletadas em três locais representativos sob cada fitofisionomia, a cada 5 cm de profundidade, até 50 cm. As substâncias húmicas dessas amostras foram fracionadas, assim como calculados os valores de &#948;13C e &#948;15N nas frações húmicas, respectivamente a partir da determinação dos isótopos estáveis 12C e 13C e 14N e 15N. Os teores de lignina e seus valores de &#948;13C são mais elevados na vegetação e MOS sob FES em relação à vegetação e MOS sob CLU. Os teores de humina são mais elevados entre as substâncias húmicas na MOS, sob as duas fitofisionomias; os de ácidos húmicos são mais elevados na MOS sob CLU, em relação à FES; e os de ácidos fúlvicos são mais elevados na MOS sob a FES, em relação ao CLU. O &#948;13C da lignina apresenta similaridade elevada em relação ao &#948;13C da humina, dos ácidos húmicos e dos ácidos fúlvicos. As variações na composição lignocelulósica das espécies que colonizam o CLU e a FES promovem diferenças nas taxas e nos produtos da humificação da MOS.<br>Much of the organic matter of a typical peat consists of humic substances, mainly formed via humification of organic residues, decomposed by soil microorganisms, and by the polymerization of organic compounds to functional macromolecules, which are normally more resistant to degradation. The fundamental pathways governing the humification of soil organic matter (SOM) are not well understood so far, and most available data about the identified chemical precursors of humic substances and the main chemical routes by which they are transformed in the peat environment are still poorly understood. What is clear is that all routes involve lignin as a chemical intermediate. Stable isotopes (&#948;13C, &#948;15N) can be used to trace humification processes of the soil organic matter (SOM), by identifying their precursors. The purpose of this study was to compare the isotopic composition of vegetation materials from the two bog vegetation types that colonize a tropical highland peatland: moist grassland (CLU) and semideciduous forest (FES), based on the isotopic composition of humic substances of SOM. The whole area of the studied peatland occupies 81.75 ha. To identify the isotopic and lignocellulosic vegetation composition, materials of the dominant species of each vegetation type were sampled. Soil samples were collected from three representative sites per vegetation type, at intervals of 5 cm from the surface down to a depth of 50 cm. The humic substances were isolated from these samples; signals of &#948;13C and &#948;15N were determined for the humic fractions. The lignin and and &#948;13C values were higher in vegetation and SOM under FES than in SOM under CLU. Humin contents were high in SOM under both vegetation types; the levels of humic acids were higher in SOM under CLU than in FES; fulvic acid contents were higher in SOM under FES than CLU. The 13C values for lignin were highly similar to those for humic acids and fulvic acids. Variations in the lignocellulosic composition of the species that colonize the CLU and FES promote different rates and SOM humification products