Soil–Atmosphere Exchange of Nitrous Oxide, Nitric Oxide, Methane, and Carbon Dioxide in Logged and Undisturbed Forest in the Tapajos National Forest, Brazil

Selective logging is an extensive land use in the Brazilian Amazon region. The soil–atmosphere fluxes of nitrous oxide (N2O), nitric oxide (NO), methane (CH4), and carbon dioxide (CO2) are studied on two soil types (clay Oxisol and sandy loam Ultisol) over two years (2000–01) in both undisturbed forest and forest recently logged using reduced impact forest management in the Tapajos National Forest, near Santarem, Para, Brazil. In undisturbed forest, annual soil–atmosphere fluxes of N2O (mean ± standard error) were 7.9 ± 0.7 and 7.0 ± 0.6 ng N cm−2 h−1 for the Oxisol and 1.7 ± 0.1 and 1.6 ± 0.3 ng N cm−2 h−1 for the Ultisol for 2000 and 2001, respectively. The annual fluxes of NO from undisturbed forest soil in 2001 were 9.0 ± 2.8 ng N cm−2 h−1 for the Oxisol and 8.8 ± 5.0 ng N cm−2 h−1 for the Ultisol. Consumption of CH4 from the atmosphere dominated over production on undisturbed forest soils. Fluxes averaged −0.3 ± 0.2 and −0.1 ± 0.9 mg CH4 m−2 day−1 on the Oxisol and −1.0 ± 0.2 and −0.9 ± 0.3 mg CH4 m−2 day−1 on the Ultisol for years 2000 and 2001. For CO2 in 2001, the annual fluxes averaged 3.6 ± 0.4 μmol m−2 s−1 on the Oxisol and 4.9 ± 1.1 μmol m−2 s−1 on the Ultisol. We measured fluxes over one year each from two recently logged forests on the Oxisol in 2000 and on the Ultisol in 2001. Sampling in logged areas was stratified from greatest to least ground disturbance covering log decks, skid trails, tree-fall gaps, and forest matrix. Areas of strong soil compaction, especially the skid trails and logging decks, were prone to significantly greater emissions of N2O, NO, and especially CH4. In the case of CH4, estimated annual emissions from decks reached extremely high rates of 531 ± 419 and 98 ± 41 mg CH4 m−2 day−1, for Oxisol and Ultisol sites, respectively, comparable to wetland emissions in the region. We calculated excess fluxes from logged areas by subtraction of a background forest matrix or undisturbed forest flux and adjusted these fluxes for the proportional area of ground disturbance. Our calculations suggest that selective logging increases emissions of N2O and NO from 30% to 350% depending upon conditions. While undisturbed forest was a CH4 sink, logged forest tended to emit methane at moderate rates. Soil–atmosphere CO2 fluxes were only slightly affected by logging. The regional effects of logging cannot be simply extrapolated based upon one site. We studied sites where reduced impact harvest management was used while in typical conventional logging ground damage is twice as great. Even so, our results indicate that for N2O, NO, and CH4, logging disturbance may be as important for regional budgets of these gases as other extensive land-use changes in the Amazon such as the conversion of forest to cattle pasture

Experimentally induced root mortality increased nitrous oxide emission from tropical forest soils

We conducted an experiment on sand and clay tropical forest soils to test the short‐term effect of root mortality on the soil‐atmosphere flux of nitrous oxide, nitric oxide, methane, and carbon dioxide. We induced root mortality by isolating blocks of land to 1 m using trenching and root exclusion screening. Gas fluxes were measured weekly for ten weeks following the trenching treatment. For nitrous oxide there was a highly significant increase in soil‐atmosphere flux over the ten weeks following treatment for trenched plots compared to control plots. N2O flux averaged 37.5 and 18.5 ng N cm−2 h−1 from clay trenched and control plots and 4.7 and 1.5 ng N cm−2 h−1 from sand trenched and control plots. In contrast, there was no effect for soil‐atmosphere flux of nitric oxide, carbon dioxide, or methane

Fine root dynamics and trace gas fluxes in two lowland tropical forest soils

Fine root dynamics have the potential to contribute significantly to ecosystem-scale biogeochemical cycling, including the production and emission of greenhouse gases. This is particularly true in tropical forests which are often characterized as having large fine root biomass and rapid rates of root production and decomposition. We examined patterns in fine root dynamics on two soil types in a lowland moist Amazonian forest, and determined the effect of root decay on rates of C and N trace gas fluxes. Root production averaged 229 ( 35) and 153 ( 27) gm 2 yr 1 for years 1 and 2 of the study, respectively, and did not vary significantly with soil texture. Root decay was sensitive to soil texture with faster rates in the clay soil (k5 0.96 year 1) than in the sandy loam soil (k5 0.61 year 1),leading to greater standing stocks of dead roots in the sandy loam. Rates of nitrous oxide (N2O) emissions were significantly greater in the clay soil (13 1ngNcm 2 h 1) than in the sandy loam (1.4 0.2 ngNcm 2 h 1). Root mortality and decay following trenching doubled rates of N2O emissions in the clay and tripled them in sandy loam over a 1-year period. Trenching also increased nitric oxide fluxes, which were greater in the sandy loam than in the clay. We used trenching (clay only) and a mass balance approach to estimate the root contribution to soil respiration. In clay soil root respiration was 264–380 gCm 2 yr 1, accounting for 24% to 35% of the total soil CO2 efflux. Estimates were similar using both approaches. In sandy loam, root respiration rates were slightly higher and more variable (521 206 gCm2 yr 1) and contributed 35% of the total soil respiration. Our results show that soil heterotrophs strongly dominate soil respiration in this forest, regardless of soil texture. Our results also suggest that fine root mortality and decomposition associated with disturbance and land-use change can contribute significantly to increased rates of nitrogen trace gas emissions

Prediction of postoperative facial swelling, pain and trismus following third molar surgery based on preoperative variables

Objective: This paper investigates the relationship between preoperative findings and short-term outcome in third molar surgery. Study design: A prospective study was carried out involving 80 patients who required 160 surgical extractions of impacted mandibular third molars between January 2009 and December 2010. All extractions were performed under local anesthesia by the same dental surgeon. Swelling and maximal inter-incisor distance were measured at 48 h and on the 7th day postoperatively. Mean visual analogue pain scores were determined at four different time periods. Results: One-hundred eight (67.5%) of the 160 extractions were performed on male subjects and 52 (32.5%) were performed on female subjects. Median age was 22.46 years. The amount of facial swelling varied depending on gender and operating time. Trismus varied depending on gender, operating time and tooth sectioning. The influence of age, gender and operating time varied depending on the pain evaluation period (p < 0.05). Conclusions: Short-term outcomes of third molar operations (swelling, trismus and pain) differ depending on the patients' characteristics (age, gender and body mass index). Moreover, surgery characteristics such as operating time and tooth sectioning were also associated with postoperative variables

Diazotrophic organisms and arbuscular mycorrhizal fungi in the establishment of cassava plants

Cassava is an important food base and an excellent alternative source of carbohydrates, especially in developing countries. As it is an easy-to-manage crop, it can be grown in small areas and does not require high soil fertility. This culture has a symbiotic relationship with arbuscular mycorrhizal fungi (AMF), which expand the extent of the roots by the projection of their hyphae, which favors the absorption of water and nutrients from the soil and with nitrogen-fixing bacteria. The objective of this work was to evaluate the interaction of nitrogen-fixing bacteria with arbuscular mycorrhizal fungi at the initial stage of cassava culture. The following parameters were evaluated: the day of sprouting, plant height, root length, plant volume, colonization rate of mycorrhizal fungi and the genera of arbuscular mycorrhizal fungi. Plants inoculated with AMF and diazotrophic bacteria presented the lowest day of sprouting, the highest plant height and longer root length. Mycorrhizal interactions with and without inoculation with nitrogen-fixing bacteria were classified, and mycorrhizal fungi of the genera Acaulospora, Diversispora, Glomus and Gigaspora were classified.A mandioca é um importante alimento na base alimentar, ótima fonte alternativa de carboidratos, especialmente em países em desenvolvimento. Por ser uma cultura de fácil manejo, pode ser cultivada em pequenas áreas e não exige alta fertilidade do solo. Esta cultura possui relação simbiótica com fungos micorrízicos arbusculares (FMA), que ampliam a extensão das raízes pela projeção de suas hifas, o que favorece a absorção de água e nutrientes do solo e com bactérias fixadoras de nitrogênio. O objetivo com este trabalho foi avaliar a interação das bactérias fixadoras de nitrogênio com os fungos micorrízicos arbusculares no estádio inicial da cultura da mandioca. Foram avaliados: o dia da brotação, altura da planta, comprimento das raízes, volume da planta, a taxa de colonização dos fungos micorrízicos e foram classificados os gêneros dos fungos micorrízicos arbusculares. As plantas inoculadas com FMA e bactérias diazotróficas apresentaram o menor dia da brotação, a maior altura da planta e maior comprimento de raízes. Houve interação micorrízica com e sem inoculação com bactérias fixadoras de nitrogênio e foram classificados fungos micorrízicos dos gêneros: Acaulospora, Diversispora, Glomus e Gigaspora

Hydrological niche segregation defines forest structure and drought tolerance strategies in a seasonal Amazon forest

The relationship between rooting depth and above‐ground hydraulic traits can potentially define drought resistance strategies that are important in determining species distribution and coexistence in seasonal tropical forests, and understanding this is important for predicting the effects of future climate change in these ecosystems.We assessed the rooting depth of 12 dominant tree species (representing c. 42% of the forest basal area) in a seasonal Amazon forest using the stable isotope ratios (δ18O and δ2H) of water collected from tree xylem and soils from a range of depths. We took advantage of a major ENSO‐related drought in 2015/2016 that caused substantial evaporative isotope enrichment in the soil and revealed water use strategies of each species under extreme conditions. We measured the minimum dry season leaf water potential both in a normal year (2014; Ψnon‐ENSO) and in an extreme drought year (2015; ΨENSO). Furthermore, we measured xylem hydraulic traits that indicate water potential thresholds trees tolerate without risking hydraulic failure (P50 and P88).We demonstrate that coexisting trees are largely segregated along a single hydrological niche axis defined by root depth differences, access to light and tolerance of low water potential. These differences in rooting depth were strongly related to tree size; diameter at breast height (DBH) explained 72% of the variation in the δ18Oxylem. Additionally, δ18Oxylem explained 49% of the variation in P50 and 70% of P88, with shallow‐rooted species more tolerant of low water potentials, while δ18O of xylem water explained 47% and 77% of the variation of minimum Ψnon‐ENSO and ΨENSO.We propose a new formulation to estimate an effective functional rooting depth, i.e. the likely soil depth from which roots can sustain water uptake for physiological functions, using DBH as predictor of root depth at this site. Based on these estimates, we conclude that rooting depth varies systematically across the most abundant families, genera and species at the Tapajós forest, and that understorey species in particular are limited to shallow rooting depths.Our results support the theory of hydrological niche segregation and its underlying trade‐off related to drought resistance, which also affect the dominance structure of trees in this seasonal eastern Amazon forest.Synthesis. Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest.Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146869/1/jec13022_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146869/2/jec13022.pd

Hydrological niche segregation defines forest structure and drought tolerance strategies in a seasonal Amazon forest

The relationship between rooting depth and above‐ground hydraulic traits can potentially define drought resistance strategies that are important in determining species distribution and coexistence in seasonal tropical forests, and understanding this is important for predicting the effects of future climate change in these ecosystems.We assessed the rooting depth of 12 dominant tree species (representing c. 42% of the forest basal area) in a seasonal Amazon forest using the stable isotope ratios (δ18O and δ2H) of water collected from tree xylem and soils from a range of depths. We took advantage of a major ENSO‐related drought in 2015/2016 that caused substantial evaporative isotope enrichment in the soil and revealed water use strategies of each species under extreme conditions. We measured the minimum dry season leaf water potential both in a normal year (2014; Ψnon‐ENSO) and in an extreme drought year (2015; ΨENSO). Furthermore, we measured xylem hydraulic traits that indicate water potential thresholds trees tolerate without risking hydraulic failure (P50 and P88).We demonstrate that coexisting trees are largely segregated along a single hydrological niche axis defined by root depth differences, access to light and tolerance of low water potential. These differences in rooting depth were strongly related to tree size; diameter at breast height (DBH) explained 72% of the variation in the δ18Oxylem. Additionally, δ18Oxylem explained 49% of the variation in P50 and 70% of P88, with shallow‐rooted species more tolerant of low water potentials, while δ18O of xylem water explained 47% and 77% of the variation of minimum Ψnon‐ENSO and ΨENSO.We propose a new formulation to estimate an effective functional rooting depth, i.e. the likely soil depth from which roots can sustain water uptake for physiological functions, using DBH as predictor of root depth at this site. Based on these estimates, we conclude that rooting depth varies systematically across the most abundant families, genera and species at the Tapajós forest, and that understorey species in particular are limited to shallow rooting depths.Our results support the theory of hydrological niche segregation and its underlying trade‐off related to drought resistance, which also affect the dominance structure of trees in this seasonal eastern Amazon forest.Synthesis. Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest.Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146869/1/jec13022_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146869/2/jec13022.pd

Influência do extrato de Crassiphycus birdiae na qualidade sanitária e fisiológica em sementes de gergelim / Influence Crassiphycus birdiae extract on the health physiological quality of sesame seeds

O Sesamum indicum L. é uma espécie bastante difundida na região Semiárida do Nordeste brasileiro, por isso a elevada qualidade sanitária e fisiológica caracteriza-se como fator primordial para o aumento na produtividade. No entanto, o uso de produtos alternativos como a Crassiphycus birdiae é responsável pelo efeito antifúngico e pode atuar como estimuladores no desempenho fisiológico dos vegetais. Portanto, o presente estudo objetivou avaliar o potencial do extrato aquoso da alga vermelha sob a qualidade sanitária e fisiológica em sementes de gergelim. O experimento foi conduzido no Laboratório de Análise e Pesquisa em Sementes da Unidade Acadêmica Especializada em Ciências Agrárias (EAJ/UFRN), Macaíba-RN. As algas vermelhas foram coletadas de bancos naturais na praia do Sagi (Latitude: 6° 28’ 00’’ Sul, Longitude: 34º 58’ 17’’ Oeste), litoral do Rio Grande do Norte, acondicionadas em caixas térmicas e enviadas ao laboratório de Análise e Pesquisa em Sementes (EAJ/Macaíba-RN). Posteriormente transportadas para o Laboratório de Química Analítica do Campus Central da UFRN para a obtenção do extrato. Em seguida, diluiu-se em água, obtendo as seguintes concentrações: 0, 5, 10, 15 e 20 µg/mL onde as sementes foram emergidas e distribuídas em dupla camada de papel filtro umedecidas com ADE (água destilada esterilizada), incubadas em placas de Petri e mantidas em B.O.D. com temperatura 25 ± 2 ºC e fotoperíodo com luz alternada (12 horas claro e 12 horas escuro) durante sete dias. Para comprovar os efeitos das concentrações sobre percentual de sementes infestadas, os resultados foram calculados e expressos em porcentagem (%). Para a qualidade fisiológica, as sementes de S. indicum foram embebidas no extrato por 24 h, acondicionadas em papel Germitest umedecido com o extrato 2,5 vezes o peso do substrato. E realizado o teste de umidade (U), germinação (G), índice de velocidade de germinação (IVG), emergência (E). Utilizando o Software Image J® foi possível avaliar o comprimento total, a parte aérea e o hipocótilo de dez plântulas retiradas ao acaso de cada repetição. O DIC foi em esquema fatorial 2 (Lotes) x 5 (Concentrações). Os dados foram submetidos à ANOVA pelo teste F, e quando significativos, foi feita a análise de regressão e os qualitativos pelo teste de Tukey (P ? 0,05), utilizando o software R. As maiores concentrações do extrato de C. birdiae proporcionaram os melhores desempenhos sanitários e fisiológicos em sementes de gergelim

Síndrome de Ehrlers-Danlos: Ehrlers-Danlos Syndrome

INTRODUÇÃO: A Síndrome de Ehlers-Danlos (SED) refere-se a distúrbios hereditários do tecido conjuntivo e da função do colágeno provocando como manifestações principais a hiperextensibilidade da pele, a hipermobilidade articular e a fragilidade de tecidos. De acordo com a Classificação Internacional de 2017, são reconhecidos 13 diferentes subtipos que caracterizam a sua extensa variabilidade clínica, por conseguinte, seu difícil diagnóstico. Embora apresente rara incidência, possui alta complexidade no tratamento multidisciplinar de suas complicações clínicas, o que motiva maior produção de literatura científica, ainda escassa, principalmente em território nacional. APRESENTAÇÃO DO CASO: M.M.V.R., 30 anos, sexo feminino, raça branca, G2P2, com história familiar positiva para hipermobilidade articular com queixa de dor crônica que piorou há cerca de 15 anos, associado a sintomas gastrointestinais, dermatológicos e vasculares. DISCUSSÃO: Realizou-se o diagnóstico de SED, com base na história clínica e no exame físico, utilizando-se os critérios de Beighton, a paciente foi encaminhada para acompanhamento multidisciplinar, com adesão ao tratamento observou-se melhora na qualidade de vida da paciente. CONCLUSÃO: É de se notar, portanto, que a SED é extremamente complexa desde o diagnóstico ao manejo, porém, este relato evidenciou que o diagnóstico precoce associado a um projeto terapêutico multidisciplinar pode trazer resultados impactantes