Dinâmica da serapilheira e fluxos de Gases de Efeito Estufa em plantios de eucalipto e vegetação nativa do Cerrado

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Florestal, 2018.Em ecossistemas florestais a dinâmica da serapilheira e os fluxos de Gases de Efeito Estufa pode variar ao longo do tempo, de acordo com as condições edafoclimáticas de cada região. Solos florestais são importantes fontes de N2O e comumente possuem comportamento de dreno em relação ao CH4. Entretanto, é importante considerar a variabilidade temporal desses fluxos. Este estudo avaliou a dinâmica sazonal, bem como as interações com os condutores ambientais da serapilheira e dos fluxos de CH4 e N2O de solos sob plantios de eucaliptos e vegetação nativa do Cerrado. O estudo foi realizado no Distrito Federal, Brasil em três áreas: plantações de eucaliptos híbridos (Eucalyptus urophylla x Eucalyptus grandis) implantados em 2011 (E1) e em 2009 (E2) e vegetação nativa do Cerrado (CE). Para isso, procederam as coletas da serapilheira produzida, estocada e sua massa remanescente, ao longo de 720 dias. A avaliação da massa remanescente de serapilheira, em cada área foi realizada a partir da distribuição aleatória de litter bags sobre o solo. Foram realizadas análises químicas e dos componentes estruturais da parede celular da serapilheira remanescente. Também foi determinado o C estocado na serapilheira. Para coleta de gases as amostras de ar foram coletadas usando uma câmara de fechamento manual e a concentração de gás foi determinada por cromatografia gasosa. A temperatura do ar e do solo, o espaço poroso saturado por água (EPSA) e as concentrações de nitrogênio mineral, nitrato (NO3 -) e amônio (NH4 +) também foram monitorados. O comportamento dos fluxos diários de gases foi analisado para cada época (chuvosa e seca) e ano (acumulado anual). Como principais resultados foi verificado efeito da sazonalidade na produção de serapilheira. Para ambos os anos de avaliação foi observada maior biomassa e C na serapilheira no E2. Em contrapartida, a maior taxa de decomposição foi para o CE, especialmente no segundo ano de avaliação (massa remanescente aos 720 dias de 35 %, 37 % e 23 % para E1, E2 e CE, respectivamente), o que foi atribuído a maior liberação aparente de N, umidade do solo e biodiversidade na área nativa. Os teores de lignina aumentaram, os de celulose diminuíram e os de hemicelulose ficaram estáveis ao longo dos 720 dias, sugerindo que a decomposição da celulose é proporcional à perda de serapilheira e que a resistência à decomposição de lignina ocorre pelo menos até dois anos de avaliação. Também foi observado um aumento na concentração dos nutrientes N e P da massa remanescente e correlações positivas entre massa remanescente e as relações C:N e C:P. A relação C:N da serapilheira foi ≥ 76:1 no tempo 0 e ≥ 30:1 aos 720 dias para as três áreas. Os resultados do presente estudo reforçam a importância de pesquisas de longo prazo principalmente para decomposição de serapilheiras em ecossistemas florestais. Quanto aos fluxos de CH4 e N2O não houve um padrão claro em resposta às variações sazonais entre as áreas. Durante o período de estudo os fluxos médios de CH4 foram -22,48 -8,38 e -1,31 μg e os fluxos médios de N2O foram 5,45, 4,85 e 3,85 μg de para as áreas de E1, E2 e CE, respectivamente. Ao longo do período de avaliação, os influxos acumulados de CH4 foram de -1,86 a -0,63 kg ha-1 ano-1 (ano 1) e de -1,85 a -1,34 kg ha-1 ano-1 (ano 2). Os fluxos cumulativos de N2O nas três áreas foram ≤ 0,85 kg ha-1 ano -1 no ano 1 e ≤ 0,44 kg ha-1 ano-1 no ano 2. Esta avaliação também sugeriu que os picos de fluxos de CH4 e N2O ocorrem apenas alguns dias por ano e, portanto, têm pouco impacto nos fluxos anuais totais. A análise de todo o período de estudo indicou a captação de CH4 da atmosfera e a contribuição do CH4 e N2O para o potencial de aquecimento global (PAG) variou de 82 a 228 Kg CO2 eq ha-1 ano-1 para os plantios de eucalipto e de 57 a 82 Kg CO2 eq ha-1 ano-1 e vegetação nativa do Cerrado, e que conversão das áreas de uso para plantios florestais representou uma opção efetiva para a mitigação do potencial de emissão de gases de efeito estufa.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).In forest ecosystems the litter dynamics and fluxes of the studied gases effects can vary over time, according to the edaphoclimatic conditions of each region. Forest soils are N2O sources and commonly act as CH4 sinks. However, the temporal variability of these fluxes must be taken into account. This study evaluated the seasonal dynamics as well as the interactions with the environmental drivers of the litter and CH4 and N2O fluxes from soils under eucalyptus plantations and native Cerrado vegetation. The study was carried out in Distrito Federal, Brazil, in three areas: hybrids eucalyptus plantations (Eucalyptus urophylla x Eucalyptus grandis) planted in 2011 (E1) and in 2009 (E2), and native Cerrado vegetation (CE). For this, the produced litter, stored litter and the remaining mass was collected over 720 days. The evaluation of the remaining litter mass in each area was performed from the random distribution of 648 litter bags on the soil. Chemical analyzes (N, P, C) and the structural components of the cell wall (lignin, cellulose and hemicellulose) of the remaining litter were performed. The C of the litter stock was also determined. For gas sampling the air samples were collected using manual close chamber and gas concentration was determined by gas chromatography. Air and soil temperature, water-filled pore space (WFPS), and concentrations of mineral nitrogen, nitrate (NO3 -), and ammonium (NH4 +) were also monitored. The behavior of the daily gas fluxes was analyzed for each season (rainy and dry) and year (annual cumulative total). The main results showed seasonal effect on litter production. For both years of evaluation were observed higher biomass and C content in litter at E2. In contrast, the highest decomposition rate was for the CE, especially in the second year of evaluation (mass remaining at 720 days of 35 %, 37 % and 23 % for E1, E2 and CE, respectively), attributed to the higher apparent liberation of N, soil moisture and biodiversity in the native area. Lignin contents increased, cellulose decreased, and hemicellulose remained stable throughout the 720 days, suggesting that the cellulose decomposition is proportional to the loss of litter and that resistance to lignin decomposition occurs at least up to two years of evaluation. It was also observed an increase in the N and P nutrients concentration of the remaining mass and positive correlations among the remaining mass and the C:N and C:P ratios. The C:N ratio of litter was ≥ 76:1 at time 0 and ≥ 30:1 at 720 days for the three areas. The results of the present study reinforce the importance of long term research, mainly for the decomposition of litter in forest ecosystems. As for the CH4 and N2O fluxes there was no clear pattern in response to seasonal variations between areas. During the study period, mean CH4 fluxes were -22.48 -8.38 and -1.31 and the mean N2O fluxes were 5.45, 4.85 and 3.85 μg m-2 h-1 for the E1, E2 and CE, respectively. Throughout the evaluation period, cumulative CH4 influxes were -1.86 to -0.63 kg ha-1yr-1 (year-1) and -1.85 to -1.34 kg ha-1yr-1 (year-2). The cumulative N2O fluxes in the three areas were ≤0.85 kg ha-1yr-1 in year 1 and ≤0.44 kg ha-1yr-1 in year 2. This evaluation also suggested that high CH4 and N2O pulses occur on only a few days a year and therefore have little impact on the total annual fluxes. The analysis of the entire study period indicated CH4 uptake from the atmosphere and the contribution of CH4 and N2O to global warming potential (GWP) ranged from 82 to 254 Kg CO2 eq ha-1 yr-1 for eucalyptus plantations and from 83 to 98 Kg CO2 eq ha-1 yr-1 in the native vegetation of Cerrado, and that the conversion of use areas to forest plantations was an effective option for the mitigation of greenhouse gas emission potential

Litter stock in three forest types in cerrado at Distrito Federal

O estudo teve como objetivo avaliar o estoque mensal e anual de serapilheira e sazonalidade em duas fitofisionomias (Cerrado stricto sensu e Mata de Galeria) e em um povoamento de eucalipto, localizados na Fazenda Água Limpa, DF. O estoque de serapilheira foi coletado mensalmente, pelo período de um ano, com auxílio de um gabarito metálico de 0,25 m2. O material foi separado manualmente nas frações folhas, cascas, galhos, raízes, flores/frutos e material particulado. O estoque de serapilheira na Mata de Galeria (9,36 t ha-1) foi estatisticamente igual ao observado no povoamento de eucalipto (9,12 t ha-1), valores maiores que o verificado no Cerrado Típico (6,08 t ha-1). A fração folha apresentou maior quantidade nas fitofisionomias e no povoamento quando comparada às demais frações. Verificaram-se dois padrões divergentes de sazonalidade do estoque de serapilheira: maior estoque no Cerrado Típico e no povoamento de eucalipto na estação seca e maior estoque na Mata de Galeria na estação chuvosa.The aim of this study was to evaluate the monthly and annual litter stock, and the seasonality in two phytophysiognomies (Cerrado stricto sensu and Gallery Forest) and one eucalyptus plantation, located in Fazenda Água Limpa, DF. The litter stock was monthly collected by using a metal jig of 0.25 m2, during one year. The material was manually sorted into leaves, bark, twigs, roots, flowers/fruits and particulate matter. There were no significant differences in the litter stock between the Gallery Forest (9.36 t ha-1) and the eucalyptus plantation (9.12 t ha-1), which were both higher than the Cerrado stricto sensu (6.08 t ha-1). The leaf fraction presented a larger amount in the three vegetation types when compared to the other fractions. There were two different patterns of litter stock seasonality: higher litter stock in the Cerrado stricto sensu and eucalyptus plantation in the dry season; and higher stock in Gallery Forest in the rainy season

Modeling deforestation in the state of Rondônia

This study applied a deforestation model for the entire State of Rondônia assuming three scenarios of deforestation: business as usual, optimistic and pessimistic. Those scenarios were constructed for the time-period of 2012-2050 using the Dinamica EGO software. Rondônia deforestation dataset was provided by the Agência Ambiental do Estado de Rondônia (Rondônia State Environmental Agency) and was used as input of the deforestation modeling. Based on this study results, we estimated that 32%, 37% and 47% of Rondônia’s native forest could be fully deforested by 2050 assuming the optimistic, business as usual and pessimistic scenarios, respectively. Regardless of the chosen scenario, we expect that deforestation will be spatially concentrated in Northern Rondônia in the next decades. The greatest concern, however, could be the integrity of the protected areas assuming the business as usual and/or pessimistic scenario. In addition, we expect a substantial increase of the forest fragmentation by 2050

Modeling Deforestation and CO2 Emissions in Tropical Forests (Western South Amazon)

Spatial modeling is a tool to represent deforestation and predict future scenarios according to different landscape change. Establishing 80% Legal Reserve Area (LR) in the Amazon since 90th, the Brazilian forestry code has made clear the biodiversity conservation profile of the largest tropical forest in the world. However, this mechanism did not prevent the advance of deforestation, which in recent years has increased again. This remote tool aims to monitor the deforestation, simulating its possible future trajectories, and thus generate information that can be used to assist in the management of deforestation reduction. The spatial modeling in the prediction of different deforestation scenarios based on public policies and their changes to the state of Acre (north of Brazil). Using the methodological processes of the Dinamica EGO software, three scenarios were projected up to the year 2050: (1) deforestation “Business as usual”, (2) deforestation with 50% LR and (3) deforestation with 80% LR provided by law. Based on these results it was evident that maintaining and respect 80% LR, it’s possible reduce the CO2 emissions more than 76%, avoiding around 119,534,836 t of CO2 and influences positively on reducing deforestation. Dinamica EGO proved to be an effective to represent the deforestation

DIVERSIDADE DE INVERTEBRADOS EM DIFERENTES USOS DO SOLO NA FLORESTA DA AMAZÔNIA

The objective was to evaluate the effects of different land use systems on soil quality. The study was carried out at the Confiança Experimental Field - Embrapa - RR. Eight land uses were evaluated in 50 x 50 m plots; forest, capoeira (a kind of secondary forest), managed capoeira, agroforestry without using inputs, agroforestry using inputs, altered pasture, managed pasture and a peach palm/heart palm production system. Mesofauna was obtained using a Berlese-Tullgren funnel, samples were collected with a 5 x 5 cm probe, introduced into the soil at a depth of 5 cm. The samples were sorted using the group experts key. The following were evaluated: biological characterization of the mesofauna and frequency and diversity of the Collembola group. The environments showed high diversification of mesofauna orders, with the highest frequencies in environments with greater ground cover. The use of peach palm/heart palm soil stood out, with high diversity of order and individuals, equivalent to environments with greater soil cover. Invertebrates soil diversity can be better studied and is a good indicator of soil quality.O objetivo foi avaliar os efeitos de diferentes sistemas do uso da terra na qualidade do solo. O estudo foi realizado no Campo Experimental Confiança - Embrapa - RR. Foram avaliados oito usos da terra em parcelas de 50 x 50 m; floresta, capoeira, capoeira manejada, agrofloresta sem insumos, agrofloresta com insumos, pastagem alterada, pastagem manejada e um sistema de produção de pupunha/palmito. Em cada uso do solo projetou-se sobre um transecto na diagonal do terreno, para obtenção de cinco pontos amostrais, onde foram realizadas coletas de solo/serapilheira. A mesofauna foi obtida utilizando funil de Berlese-Tullgren, as amostras foram coletadas com sonda de 5 x 5 cm, introduzida no solo a 5 cm de profundidade. As amostras foram triadas adontando-se a chave de especialistas do grupo. Foram avaliadas: caracterização biológica da mesofauna e frequência e diversidade do grupo Collembola. Os ambientes apresentaram elevada diversificação de ordens de mesofauna, com as maiores frequências em ambientes com maior cobertura do solo. Houve destaque no uso do solo pupunheira/palmito, com alta diversidade de ordem e indivíduos, equivalentes aos ambientes de maior cobertura do solo. A diversidade de invertebrados do solo pode ser mais bem estudada e apresenta-se como bom indicador de qualidade do solo. Palavras-chave: ação antrópica; manejo do solo; biodiversidade.   Land use on the diversity of soil invertebrates in the forest region of the amazon   ABSTRACT: The objective was to evaluate the effects of different land use systems on soil quality. The study was carried out at the Confiança Experimental Field - Embrapa - RR. Eight land uses were evaluated in 50 x 50 m plots; forest, capoeira (a kind of secondary forest), managed capoeira, agroforestry without using inputs, agroforestry using inputs, altered pasture, managed pasture and a peach palm/heart palm production system. Mesofauna was obtained using a Berlese-Tullgren funnel, samples were collected with a 5 x 5 cm probe, introduced into the soil at a depth of 5 cm. The samples were sorted using the group experts key. The following were evaluated: biological characterization of the mesofauna and frequency and diversity of the Collembola group. The environments showed high diversification of mesofauna orders, with the highest frequencies in environments with greater ground cover. The use of peach palm/heart palm soil stood out, with high diversity of order and individuals, equivalent to environments with greater soil cover. Invertebrates soil diversity can be better studied and is a good indicator of soil quality. Keywords: human action; soil management; diversity

CH4 and N2O fluxes from planted forests and native Cerrado ecosystems in Brazil

Forest soils are N2O sources and commonly act as CH4 sinks. This study evaluated the dynamics of the CH4 and N2O fluxes of soils under Eucalyptus plantations and native Cerrado vegetation, as well as possible interactions between environmental factors and fluxes. The study was carried out in the Distrito Federal, Brazil, during 26 months, in three areas: in two stands of the hybrid Eucalyptus urophylla × Eucalyptus grandis, planted in 2011 (E1), and in 2009 (E2) and native Cerrado vegetation (CE). Measurements to determine the fluxes in a closed static chamber were carried out from Oct 2013 to Nov 2015. Soil and climate factors were monitored. During the study period, the mean CH4 fluxes were –22.48, –8.38 and –1.31 μg CH4 m–2 h–1 and the mean N2O fluxes 5.45, 4.85 and 3.85 μg N2O m–2 h–1 from E1, E2 and CE, respectively. Seasonality affected plantations in the studied sites. Cumulative CH4 influxes were calculated (year-1: –1.86 to -0.63 kg ha–1 yr–1; year-2: –1.85 to –1.34 kg ha–1 yr–1). Cumulative N2O fluxes in the three sites were ≤ 0.85 kg ha–1 yr–1. The change in land use from Cerrado to Eucalyptus plantations did not significantly changed regarding greenhouse gases (GHG), compared to the native vegetation. Flux rates of both gases (N2O and CH4) were low. Temporal variations in GHG fluxes and different ages of the stands did not cause significant differences in cumulative annual fluxes

Relationships between soil properties and species establishment in the restoration of mined soils in the cerrado biome

Restoring the ecosystems of the Cerrado biome is challenging considering the diversity of phytophysiognomies present in the biome, some of which are composed of species from different strata (herbaceous, shrubby, and arboreal), which increases the complexity of restructuring the floristic composition. Other factors was involved, such as soil quality, which directly influences the success of restoration, water storage, and nutrients, the financial costs, and a slow ecological process, due to the adverse circumstances found in the area. be restored. The strong anthropogenic interventions by mining processes reduce dramatically the physical and nutritional composition of the soil. We studied two restoration areas in Paracatu, Brazil, to examine their edaphic conditions six years after mining activities ceased and relate them to the status of the restoration process. In 2009, a Cerrado restoration were established in an area previously explored for gravel extraction. Plants were sampled and identified in 11 transects along the planting lines. The diameter base (DB) and total height (HT) were measured. The physical/chemical quality of the soil substrate was determined using a collection of samples in open trenches at four types of points: Cerrado (TC); dead plant pits (TM); seedling pits having living individuals of the most abundant species (TT); and those of the second-most abundant species (TE). Cecropia pachystachya Trécul and Tapirira guianensis Aubl. were most abundant and demonstrated the potential to thrive in areas degraded by mining having low mortality rates and growth at relatively DB and HT. The physical quality indicators in the gravel pits were not limiting, indicating that substrate preparation was efficient in this regard. The organic matter content in TM, TT, and TE was low in comparison to that of TC, and the chemical conditions in the TE pit substrates were similar to those in TM pits, suggesting C. pachystachya is a species with good plasticity, whereas T. guianensis is present in pits with higher levels of phosphorus

Modeling biomass and nutrients in a eucalyptus stand in the cerrado

The prediction of biological processes, which involve growth and plant development, is possible via the adjustment of mathematical models. In forest areas, these models assist in management practices, silviculture, harvesting, and soil fertility. Diameter, basal area, and height are predictors of volume and biomass estimates in forest stands. This study utilized different non-linear models for estimating biomass and nutrient values in the aerial biomass and roots of an unmanaged eucalypt stand in Cerrado dystrophic soil. It was hypothesized that the models would estimate the nutrients of the aboveground biomass and roots after meeting the selection and validation criteria. By statistical analysis of the parameters and subsequent validation, the Schumacher–Hall model was presented to be the best fit for biomass and nutrients. This result confirmed the ability of different variables, including diameter, basal area, and height, to be predicted. Estimating the nutrient values in the aboveground biomass and roots allowed a better understanding of the quality of the vegetal residues that remained in the soil. For dystrophic soils, which occur in the Cerrado, these estimates become even more relevant

Estoque de Serapilheira em Três Fisionomias no Cerrado do Distrito Federal

RESUMO O estudo teve como objetivo avaliar o estoque mensal e anual de serapilheira e sazonalidade em duas fitofisionomias (Cerrado stricto sensu e Mata de Galeria) e em um povoamento de eucalipto, localizados na Fazenda Água Limpa, DF. O estoque de serapilheira foi coletado mensalmente, pelo período de um ano, com auxílio de um gabarito metálico de 0,25 m2. O material foi separado manualmente nas frações folhas, cascas, galhos, raízes, flores/frutos e material particulado. O estoque de serapilheira na Mata de Galeria (9,36 t ha-1) foi estatisticamente igual ao observado no povoamento de eucalipto (9,12 t ha-1), valores maiores que o verificado no Cerrado Típico (6,08 t ha-1). A fração folha apresentou maior quantidade nas fitofisionomias e no povoamento quando comparada às demais frações. Verificaram-se dois padrões divergentes de sazonalidade do estoque de serapilheira: maior estoque no Cerrado Típico e no povoamento de eucalipto na estação seca e maior estoque na Mata de Galeria na estação chuvosa

Conteúdo de nutrientes na serapilheira em três fisionomias do Cerrado do Distrito Federal

O estudo foi realizado na Fazenda Água Limpa, DF, em três fisionomias: Cerrado típico, mata de galeria e povoamento de Eucalyptus urograndis, e teve por objetivo analisar o conteúdo de macro e micronutrientes via estoque de serapilheira, durante as épocas seca e chuvosa. Procedeu-se a coleta mensal de serapilheira no período de setembro de 2011 a agosto de 2012. As amostras foram coletadas aleatoriamente, com três repetições em cada fisionomia sendo secas para posterior determinação dos teores de nutrientes. Os resultados foram avaliados por análise de variância, teste de Tukey e correlação de Pearson. Os conteúdos de macronutrientes no estoque de serapilheira na Mata de Galeria e eucalipto apresentaram-se na ordem de N > Ca > K > Mg > S > P no período chuvoso, e no seco o S foi superior ao Mg para o eucalipto, não sendo observada alteração na Mata de Galeria. No Cerrado típico, a ordem foi N > Ca > S > Mg > K > P no período chuvoso, alterando para N > Ca > K > S > Mg > P no período seco