Bibliometrics of Cambodian Science: subjects, researchers and impact in the Science Citation Index Expanded / Bibliometría de la ciencia camboyana: temas, investigadores e impacto en el Science Citation Index Expanded

Abstract Introduction: Cambodia is a small agricultural tropical country for which only two small scientometric studies, published five years ago, were available until now. Objective: To identify, for Cambodian research, subjects, outlets, authors, institutions, citations and recommendations. Methods: The data were retrieved from the Science Citation Index Expanded (January 04, 2021) using the word "Cambodia" for the period 1972 to 2019. Results: We retrieved 3 689 documents: for the half century covered, the yearly presence of Cambodia in the index has grown strongly, to 325 articles and 6 555 authors in 2019 alone. Most documents are articles in English about health, particularly infectious and tropical diseases. Most international collaboration is done, by country, with the USA, France, and Thailand; and by institution, with Mahidol University, the Pasteur Institute and Oxford University. The most productive institutions are the Cambodian Ministry of Health and the Cambodian National Center for Parasitology. The main outlets are PLoS One, Malaria and PLoS Neglected Tropical Diseases. Cambodian articles are cited for up to 33 years, with a peak of 4.5 citations within the first two years. Those in English, or from well-funded foreign projects, have more citations in this particular index; especially if they are about malaria, hepatitis or influenza. Conclusions: The nature and impact of Cambodian science outside the SCI-EXPANDED remain unknown, but publications in that index have increased, concentrate on solving local problems, and depend heavily on international collaboration, following a well-known pattern of science in tropical countries. We suggest a funding system based on international peers who assign funds to the most productive researchers with minimal bureaucracy, so that local research is done on a greater variety of topics and with less participation of Cambodian researchers as low-level members in foreign projects.

Resumen Introducción: Camboya es un país tropical asiático pequeño y "subdesarrollado", con una economía basada en la agricultura, para el que hasta ahora solo estaban disponibles dos pequeños estudios cienciométricos, publicados hace cinco años. Objetivo: Identificar, para la investigación camboyana, qué se estudia; quién hizo la investigación; dónde y cuándo se publicó; y los factores que afectan su citación. Métodos: Usamos el Science Citation Index Expanded (4 de enero de 2021) utilizando la palabra "Camboya" y se limitaron al período 1972 a 2019. Resultados: Hallamos 3 689 documentos; durante el medio siglo cubierto, la presencia anual de Camboya en el índice ha aumentado considerablemente, con 325 artículos y 6 555 autores incorporados tan solo en 2019. La mayoría son artículos en inglés sobre salud, particularmente enfermedades infecciosas y tropicales. La mayor parte de la colaboración internacional se realiza, por país, con EE. UU., Francia y Tailandia; y por institución, con la Universidad Mahidol, el Instituto Pasteur y la Universidad de Oxford. Las instituciones más productivas son el Ministerio de Salud de Camboya y el Centro Nacional de Parasitología de Camboya. Las principales revistas son PLoS One, Malaria y PLoS Neglected Tropical Diseases. Los artículos camboyanos se citan hasta por 33 años, con un máximo de 4.5 citas en los dos primeros años. Los que son en inglés, o de proyectos dirigidos por el extranjero, tienen más citas en esta base de datos; particularmente si se trata de malaria, hepatitis o influenza. Conclusiones: La naturaleza y el impacto de la ciencia camboyana fuera del SCI-EXPANDED siguen sin conocerse, pero las publicaciones en ese índice han aumentado, se concentran en resolver problemas locales y dependen en gran medida de la colaboración internacional, siguiendo un patrón bien conocido en los países tropicales. Sugerimos un sistema de financiación basado en pares internacionales que asignen, con burocracia mínima, fondos a los investigadores más productivos, de modo que la investigación local se realice en una mayor variedad de temas y con una menor participación de investigadores camboyanos como miembros de bajo nivel en proyectos extranjeros.

"A most bountiful source of inspiration": Dobzhansky's evolution of tropical populations, and the science and politics of genetic variation / "A mais abundante fonte de inspiração": Dobzhansky e sua evolução sobre as populações dos trópicos, a ciência e a política da variabilidade genética

Abstract Theodosius Dobzhansky has been studied for how he integrated field naturalism and laboratory experimentation in ways that helped produce the Modern Synthesis, as well as how he leveraged biological expertise to support liberal and cosmopolitan values amidst Second World War and the Cold War. Moreover, Dobzhansky has been central in analyses of the institutionalization of genetics in Brazil, where he spent several years. This article situates Dobzhansky's Brazilian research within the science of variation and the politics of diversity. I conclude by raising questions about how the ways in which science figured in politics depended on ideas about the role of scientists in society whichwere advanced in parallel, suggesting research on the "co-production" of natural and social orders.

Resumo Theodosius Dobzhansky tem sido estudado pelo modo como ele integrou o naturalismo de campo e a experimentação científica, que deram origem à síntese moderna, assim como a alavanca que ele deu ao conhecimento biológico para apoiar valores liberais e cosmopolitas em meio à Segunda Guerra Mundial e à Guerra Fria. Além disso, Dobzhansky tem sido fundamental para a análise da institucionalização da genética no Brasil, onde ele morou e trabalhou por muito tempo. O trabalho contextualiza a pesquisa brasileira de Dobzhansky dentro da ciência da variabilidade e nas políticas de diversidade. A conclusão levanta questionamentos sobre como a ciência figurava na política dependendo das ideias sobre o papel dos cientistas na sociedade, que foram avançando em paralelo, sugerindo uma pesquisa na coprodução das ordens social e natural.

Stingless bee honeys from Soconusco, Chiapas: a complementary approach / Mieles de abejas sin aguijón del Soconusco, Chiapas: enfoque complementario

Abstract Stingless bees are located in the tropic areas, and produced a sweet natural substance called pot honey, with different properties and uses. Recently, most studies are focused on characterizing them, in order to contribute to their knowledge and the establishment of quality laws. Thus physicochemical, acceptance and palynological studies were performed in stingless bee honeys from Soconusco, Chiapas, in order to learn and contribute to their knowledge in the Tropics. Nine honey samples were collected from Melipona solani (Ms), M. beecheii (Mb) and Scaptotrigona mexicana (Sm) in different meliponaries. Our results registered physicochemical values that ranged as follow; pH 2.8-4.8, electrical conductivity (EC) 114-1211 μS/cm, free acidity 24-100 meq/kg, aw 59-71 g/100g, moisture 35-38 %, color 0.13-0.75 Pfund scale, reducing sugars 47-71 %, hidroxymethylfurfural (HMF) not determined - 2.72 mg/100g, and diastase activity 1.92-11.22 DN. On the other hand, the principal component analysis (PCA) of physicochemical values showed that 86.9 % of the total variability between species was explained by the following parameters aw, moisture, free acidity, color, pH, sugars and EC. Sm honeys were associated (PCA) with a higher water content, free acidity and darker colors, while Melipona honeys with a sweeter taste and a lower diastase activity; thus honeys could be grouped by genera. The acceptance test showed that 78 % of honeys were preferred, being the SmCa sample in the category "I likely dislike" due to the bitter taste (disapproved by consumers). The melisopalynological results showed that M. beecheii honeys are monofloral with a 45 % of Fabaceae pollen, while Melipona solani and Scaptotrigona mexicana honeys are multi or polyfloral with diferent pollen types; Fabaceae, Melastomataceae, Malvaceae and Asteraceae. From this complementary study we can asume that it is necessary to implicate researchers with producers, so they could have accesss to stingless bee honey analysis and to help them to improve meliponaries management by identifying and introducing stingless bee flora.(AU)

Resumen En las regiones tropicales se ubican las abejas sin aguijón, las cuales producen una sustancia dulce denominada miel de cántaro con propiedades y usos diferentes a los de las abejas melíferas (Apis mellifera). Actualmente, se han desarrollado diversos trabajos enfocados a su caracterización, con la finalidad de contribuir con su conocimiento y el establecimiento de estándares de calidad. En este estudio se realizaron estudios fisicoquímicos, de aceptación y palinológicos en mieles de abejas sin aguijón de Soconusco, Chiapas. Se recolectaron nueve muestras de miel de las siguientes especies: Melipona solani (Ms), M. beecheii (Mb) y Scaptotrigona mexicana (Sm) en diferentes meliponarios. Nuestros resultados registraron valores fisicoquímicos que variaron de la siguiente manera: pH 2.8-4.8, conductividad eléctrica (CE) 114-1 211 μS/cm, acidez libre 24-100 meq/kg, aw 59-71 g/100 g, humedad 35-38 %, color 0.13-0.75 escala Pfund, azúcares reductores 47-71 %, hidroximetilfurfural (HMF) no determinado - 2.72 mg/100 g, y actividad de la días-tasa 1.92-11.22 ND. Por otro lado, el análisis del componente principal (PCA) de los valores fisicoquímicos mostró que el 86.9 % de la variabilidad total entre las especies se explica por los siguientes parámetros: aw, humedad, acidez libre, color, pH, azúcares y CE. Las mieles de Sm (PCA) se asociaron con un mayor contenido de agua, acidez libre y colores más oscuros, mientras que las mieles de Melipona con un sabor más dulce y una actividad de días-tasa más baja; por lo tanto, las mieles podrían agruparse por géneros. La prueba de aceptación mostró que el 78 % de las mieles eran preferidas, siendo la muestra de SmCa en la categoría "Probablemente no me gusta" debido al sabor amargo (desaprobado por los consumidores). Los resultados melisopalinológicos mostraron que las mieles de M. beecheii son monoflorales con un 45 % de polen de Fabaceae, mientras que las mieles de M. solani y S. mexicana son multi o poliflorales con diferentes tipos de polen: Fabaceae, Melastomataceae, Malvaceae y Asteraceae. De este estudio complementario observamos que se requiere poner en contacto a investigadores y productores, para que el acceso a los análisis de las mieles de abejas sin aguijón sea posible, y así mismo se pueda ayudar con el mejoramiento del manejo de los melionarios al momento de identificar e introducir la flora preferida por las abejas sin aguijón.(AU)

Influence of gender on carcass yield of twin lambs Blackbelly x Pelibuey at 56 days of age / Influência do gênero no rendimento de carcaça em cordeiros gêmeos Blackbelly x Pelibuey aos 56 días de idade

The aim of this study was to determine the influence of gender on pre-weaning growth, yield and weight of primal cuts of the carcass of Blackbelly x Pelibuey lambs. 16 twin lambs were used. The lamb gender was the fixed factor. The variables evaluated were: body weight at birth and at weaning, average daily weight gain, weight and yield of carcass and primal cuts: neck, arm, thorax, abdomen and leg. Gender did not affect (P>0.05) body weight at birth. However, the pre-weaning average daily weight gain and body weight at weaning were affected (P<0.05) by the gender. Hot carcass yield and weight and primal cuts were not affected (P>0.05) by the gender of the lamb. Nevertheless, the area of the Longissimus dorsi muscle and cavity fat were different between males and females (P<0.05) 11.5±0.73cm2 and 198±0.05 g vs 9.3±0.73cm2 and 282±0.05g, respectively. In conclusion, in twin lambs Blackbelly x Pelibuey males had greater average daily weight gain and body weight at weaning than females. Carcass yield and weight and primal cuts were not affected by the gender of the lamb. However, males had greater area of the L. dorsi muscle than females and these in turn had a greater amount of cavity fat than males.(AU)

Objetivou-se determinar a influência do gênero no crescimento pré-desmame, no rendimento e no peso dos cortes primários de carcaça de cordeiros Blackbelly x Pelibuey. Utilizaram-se 16 cordeiros gêmeos. Os dados foram analisados em um desenho completamente ao acaso, em que o gênero dos corderos foi o fator fixo. As variáveis avaliadas foram: peso vivo ao nascimento e ao desmame, ganho diário de peso, peso e rendimento de carcaças e dos cortes primários: pescoço, braço, tórax, abdômen e perna. O gênero não afetou (P>0,05) o peso vivo ao nascimento. No entanto, o ganho diário de peso e o peso vivo ao desmame foram afetados, sendo esses valores superiores nos machos (P<0,05). O peso e o rendimento das carcaças quentes e dos cortes primários não foram afetados (P>0,05) pelo gênero do cordeiro. Entretanto, a área do músculo Longissimus dorsi e a gordura cavitária foram diferentes entre machos e fêmeas (P<0,05): 11.5±0.73cm2 e 198±0.05g vs. 9.3±0.73cm2 e 282±0.05g, respectivamente. Em conclusão, nos cordeiros gêmeos Blackbelly x Pelibuey, os machos tiveram maior ganho diário de peso e maior peso vivo ao desmame do que as fêmeas. O peso e o rendimento da carcaça bem como os cortes primários não foram afetados pelo gênero do cordeiro. Todavia, os machos tiveram maior área do músculo L. dorsi que as fêmeas e estas tiveram maior quantidade de gordura cavitária que os machos.(AU)

Vitamin D deficiency in risk groups living in tropical curaçao / Deficiencia de vitamina D en los grupos de riesgo de curazao tropical

OBJECTIVE: Curaçao (12 degrees 10N, 69 degrees 0W) is characterized by whole year abundant sunshine (8-10 hours/day). We challenged the automatic assumption that people living in tropical countries do not have a high risk of vitamin D deficiency, and investigated the vitamin D status in a tropical environment. METHODS: For this, we selected fiftytwo elderly people with little or no exposure to direct sunlight [median 84 (60-96) years; 34 females, 18 males] and who were cared for by community nurses or lived in retirement or nursing homes. Furthermore, six rehabilitating orthopaedic patients [median 72 (38-90) years; one female, five males] were included. Serum 25(OH)D, calcium, phosphate, parathyroid hormone (PTH) and creatinine were measured. Those exhibiting elevated creatinine, PTH or both had their 1,25dihydroxyvitamin D [1,25(OH)2D] examined. RESULTS: Serum levels of 25(OH)D below 25, 50 and 75 nmol/L were detected in, respectively, seven (12%), 22 (38%) and 48 (83%) of the fiftyeight persons. Four persons had combined high creatinine and PTH, and low 1,25(OH)2D, which was not known by their caregivers. CONCLUSION: Abundant sunshine outdoors is no guarantee for vitamin D sufficiency. More attention is needed for vitamin D deficiency in risk groups living in tropical areas and elderly persons with poor kidney function.

OBJETIVO: Curazao (12 grados 10N, 69 grados 0W) se caracteriza por su abundante luz solar durante todo el año (8-10 horas/día). Ponemos en duda la suposición automática de que los habitantes de países tropicales no poseen un alto riesgo de deficiencia de vitamina D, e investigamos los niveles de vitamina D en un ambiente tropical. MÉTODOS: Para ello, seleccionamos a cincuenta y dos personas de avanzada edad [mediana 84 (60-96) años; 34 mujeres, 18 hombres] con poca o ninguna exposición directa a la luz solar, cuidados por enfermeras comunitarias o que vivían en hogares de ancianos o casas de retiro. Además, se incluyeron seis pacientes bajo rehabilitación ortopédica [mediana 72 (38-90) años; una mujer, cinco hombres]. Se les realizaron las siguientes mediciones: 25(OH)D en suero, calcio, fosfato, hormona paratiroidea (HPT), y creatinina. A todos aquellos que mostraron niveles elevados de creatinina, de HPT, o de ambas, se les realizó un examen de 1,25dihidroxivitamina D [1,25(OH)2D]. RESULTADOS: Se detectaron niveles séricos de 25(OH)D por debajo de 25, 50 y 75 nmol/L en siete (12%), 22 (38%) y 48 (83%) de las cincuenta y ocho personas, respectivamente. Cuatro personas presentaron una combinación de elevada creatinina y HPT, y bajo 1,25(OH)2D, datos desconocidos para sus cuidadores. CONCLUSIÓN: La abundancia de luz solar exterior no es garantía de suficiencia de vitamina D. Se necesita prestar mayor atención a la deficiencia de vitamina D en los grupos de riesgo que viven en áreas tropicales, así como a las personas de edad avanzada con pobre función renal.

Caracterización nutricional y de la cinética de degradación ruminal dealgunos de los recursos forrajeros con potencial para la suplementaciónde rumiantes en el trópico alto de Colombia / Nutritional characterization and ruminal degradation kinetics of someforages with potential for ruminants supplementation in the highland tropics of Colombia / Caracterização nutricional e cinética de degradação ruminal de algunsdos recursos forrageiros com potencial para o suplementação de gadona nas regiões tropicais de altitude da Colômbia

El objetivo de este estudio fue caracterizar la calidad nutricional de nueve recursos forrajeros: Consuelda(Symphytum peregrinum), Morera (Morus alba), San Joaquín (Malvaviscus penduliflorus), Nacedero (Trichantheragigantea), Botón de oro (Tithonia diversifolia Hemsl. Gray), Ramio (Boehmeria nivea L. Gaud, Arboloco (Montanoa quadrangularis Bipontinus Schultz), Chachafruto (Erythrina edulis Triana ex Michelle) y Aliso (Alnus acuminata Kunth), con potencial para su inclusión en los programas de suplementación estratégica en el trópico de altura en Colombia. Los forrajes que mostraron los mayores niveles de Proteína Cruda (PC) fueron Confrey (28,42), Chachafruto (26,52%), Arboloco (26,35%) y lo que mostraron los más bajos fueron San Joaquín (15,92%) y Aliso(16,88%). Los contenidos más bajos de Fibra en Detergente Neutro (FDN) los presentaron Morera (33,55%) y Aliso(35,79%), mientras que los más altas se observaron para Chachafruto (49,64%) y Ramio (48,54%). Los contenidosde nutrientes de los forrajes evaluados pueden incluirse en planes de suplementación ya que mejoran la densidad energética de la dieta y podrían incrementar el consumo de materia seca.

The aim of this study was to characterize the nutritional quality of nine forage resources: Comfrey (Symphytum peregrinum), White Mulberry (Morus alba), Sleeping Hibiscus (Malvaviscus penduliflorus), Nacedero (Trichantheragigantea), tree marigold (Tithonia diversifolia Hemsl.) Gray, Ramie (Boehmeria nivea L.) Gaud, Arboloco (Montanoaquadrangularis Bipontinus Schultz), Chachafruto (Erythrina edulis Triana ex Michelle) and Andean Alder (Alnusacuminata Kunth), with potential for inclusion in strategic supplementation programs in the highland tropics ofColombia. The forages that showed the highest levels of PC were Comfrey (28,42%), Chachafruto (26,52%), Arboloco(26,35%) and those that showed the lowest were the Sleeping Hibiscus (15,92%) and Andean Alder (16,88%). The lowest NDF contents were presented by White Mulberry (33,55%) and Andean Alder (35,79%) while the highest wereobserved for Chachafruto (49,64%) and Ramie (48,54%). The nutrient content of forages evaluated can be included insupplementation programs, due to they can enhance the energy density of the diet and may increase dry matter intake.

O objetivo deste estudo foi caracterizar a qualidade nutricional de nove recursos forrageiros: Confrei (Symphytumperegrinum), amoreira (Morus alba), San Joaquín (Malvaviscus penduliflorus), Nacedero (Trichanthera gigantea),Botón de oro (Tithonia diversifolia Hemsl. Gray), rami (Boehmeria nivea L. Gaud), Arboloco (Montanoaquadrangularis Bipontinus Schultz), chachafruto (Erythrina edulis Triana ex Michelle) e Amieiros (Alnus acuminataKunth), com potencial para sua inclusão em programas de suplementação estratégica nas regiões tropicais de altitudeda Colômbia. As forrageiras que apresentaram os maiores níveis de PC foram Confrei (28,42%), Chachafruto(26,52%), Arboloco (26,35%) e as que mostraram os menores níveis foram a San Joaquín (15,92%) e Amieiros(16,88%). Os menores teores de FDN estavam na Amoreira (33,55%) e Amieiros (35,79%), enquanto os mais altosforam observados para Chachafruto (49,64%) e Rami (48,54%). Os conteúdos de nutrientes das forrageiras avaliadasforam incluídos nos planos de suplementação já que aumentam a densidade energética da dieta e podem aumentar aingestão de matéria seca.

Os trópicos na rota do Império britânico: a visão de Mungo Park sobre a África em fins do século XVIII / The tropics and the rise of the British Empire: Mungo Park's perspective on Africa in the late eighteenth century

O jovem médico escocês Mungo Park chegou à África em 1795, aos 23 anos, com uma missão tão específica quanto complexa naqueles tempos: percorrer o curso do rio Níger. Em 1799, o relato dessa jornada veio a público em uma publicação que vendeu 1.500 cópias em apenas um mês, estimulando o aparecimento de mais duas edições da obra no mesmo ano e sua tradução para o francês e o alemão no ano seguinte. Neste artigo, examina-se a narrativa de Mungo Park considerando-se as relações entre trópico, ciência e viagem nos primeiros tempos do expansionismo inglês sobre o interior da África.

The young Scottish physician Mungo Park, aged 23, arrived in Africa in 1795 with a mission as specific as it was complex in those bygone days, namely to travel the entire length of the River Niger. In 1799, the story of this journey was published in a book that sold 1500 copies in the first month alone, with two further editions published that same year, as well as the translation of the work into French and German the following year. In this article, the narrative of Mungo Park is examined by taking due consideration of the relationship between the tropics, science and travel in the early days of British expansionism into the heart of Africa.

Hydrochemistry and phytoplankton composition of two tidal creeks in South-Western Nigeria

As in other countries, the effects of human stressors on coastal areas and waters in Nigeria are increasing, and management strategies are urgent. In order to assess this, studies on phytoplankton composition in relation to physico- chemical characteristic of two tidal creeks in Lagos were conducted for six months (October 2007 to March 2008). Variations in some of the physical and chemical parameters such as rainfall, temperature, salinity, nitrate-nitrogen, phosphate- phosphorus, sulphate, salinity, biological oxygen demand and chemical oxygen demand influenced the phytoplankton abundance. Three major divisions were recorded for the two creeks: Bacillariophyta, Chlorophyta and Cyanophyta. Among these, diatoms were the most abundant group observed. Water quality characteristics reflected the effect of tidal influence and consequent salt water inflow, fresh water incursion and the pollution status of one of the creeks, as a result of industrial and commercial activities in the area. Rev. Biol. Trop. 58 (3): 827-840. Epub 2010 September 01.

Como en otros países, los efectos de actividades antropogénicas en las zonas costeras y las aguas de Nigeria están aumentando, y las estrategias de gestión son urgentes. Durante seis meses (octubre 2007-marzo 2008) se estudió la composición del fitoplancton en relación con las características físico-químicas de dos canales en Lagos, Nigeria. Las variaciones en algunos de los parámetros físicos y químicos tales como precipitación, temperatura, salinidad, nitrato-nitrógeno, fosfato-fósforo, sulfato, salinidad, demanda biológica de oxígeno y demanda química de oxígeno; afectan la abundancia del fitoplancton. En los dos arroyos se registraron tres divisiones principales: Bacillariophyta, Chlorophyta y Cyanophyta, las diatomeas fueron el grupo más abundante observado. Características de calidad del agua reflejan el efecto de la influencia de las mareas y la consiguiente entrada de agua salada, la incursión de agua dulce y el estado de contaminación de uno de los canales, como consecuencia de actividades industriales y comerciales en la zona.

Environmental determinants for natural regeneration of gallery forest at the Cerrado/Amazonia boundaries in Brazil / Determinantes ambientais para regeneração natural de mata de galeria na transição Cerrado/Amazônia no Brasil

Natural regeneration and structure and their relationship to environmental variables were studied in three sections of a gallery forest, in Eastern Mato Grosso, Brazil (14º43'S and 52º21'W). The assumption was that natural regeneration is constrained by environmental determinants at all stages of development of the tree community. The objective was to analyse the forest structure and to verify the relationship between species distribution and abundance at different stages of regeneration and environmental variables. In each section, 47 contiguous (10x10m) permanent plots were established to sample trees (gbh≥15cm), following a systematic design. Seedlings (0.01 to 1m height), saplings (1.01 to 2m) and poles (from 2.01m height to gbh<15cm) were sampled in sub-plots of 1x1m, 2x2m and 5x5m, respectively. In each plot, soil properties, gaps projection, bamboos, rocky cover, declivity and depth of ground watertable were determined. The relationships between the environmental variables with trees and seedling communities were assessed by canonical correspondence analysis. In spite of the sections being near to each other, they presented large differences in floristics, structure and site conditions. The forest soil presented a low cation exchange capacity and a high level of Al saturation. The occurrence of bamboos and gaps and the depth of ground watertable limited the occurrence of poles and trees. The high degree of structural heterogeneity for each regeneration category was related primarily to a humidity gradient; but soil fertility (Ca+Mg) was also a determinant of seedling and sapling communities.

Foi estudada a regeneração natural e a estrutura de três seções de uma floresta de galeria no leste de Mato Grosso, Brasil (14º43'S e 52º21'W). O objetivo foi analisar a estrutura da floresta e verificar a relação entre a distribuição e abundância das espécies nos diferentes estágios de regeneração e entre as variáveis ambientais. Em cada seção de floresta foram estabelecidas, sistematicamente, 47 parcelas (10x10m) contíguas e permanentes para amostrar as árvores (CAP≥15cm). As plântulas jovens (0,01 a 1m de altura), as plântulas maiores (1,01 a 2m) e as arvoretas (de 2,01m de altura a CAP≥15cm) foram amostradas em sub-parcelas de 1x1m, 2x2m e 5x5m, respectivamente. Para cada parcela foram determinadas as propriedades do solo, projeção das clareiras, cobertura de bambus, rochosidade, declividade e profundidade do lençol freático. A relação das variáveis ambientais com as árvores e comunidades de plântulas e arvoretas foi determinada a partir de uma análise de correspondência canônica. Apesar das seções de floresta serem próximas entre si, apresentaram diferenças importantes em relação à composição florística, estrutura e variáveis ambientais. Os solos apresentaram reduzida capacidade de troca catiônica e elevados níveis de saturação de alumínio. A ocorrência de bambus e clareiras e a profundidade do lençol freático limitam a ocorrência de arvoretas e árvores. A elevada heterogeneidade estrutural em cada categoria de regeneração esteve relacionada principalmente a um gradiente de umidade, mas a fertilidade do solo (Ca+Mg) também foi determinante nas diferentes comunidades de plântulas.

Comparación de la concentración mineral en forrajes y suelos de zonas ganaderas del estado de Quintana Roo, México / Comparison of the mineral content in forage and soil of grazing areas in the state of Quintana Roo, Mexico

The objective of this study was to determine the amount of macro and micro minerals in forages growing in three areas of the state of Quintana Roo, north (N), center (C) and south (S) and the most important forage species that grow in those areas. One hundred and eight pasture samples and 68 soil samples were collected in 45 farm units. All minerals were analyzed with atomic absorption spectrometer, except P which was analyzed by colorimetric method. Variables were analyzed using GLM procedures and means were compared using Duncan Multiple Range Test. Forage species more frequently found were Brachiaria brizantha, 73.3%; Cynodon plectostachyus, 31.1%; Pennisetum purpureum, 31.1%; Panicum maximum var Tanzania, 26.6%; P. maximum var Mombasa, 15.5%; P. maximum var Guinea, 13.3%; Brachiaria mutica, 11.1%; and Brachiaria humidicola, 11.1%. Low Ca, P and Mg levels were found in both pastures and soil, where as K and Fe were extremely abundant. Specific deficiencies of Mn (N), Zn (C) and Cu (C and S) were also found. In conclusion, there are serious imbalances in the mineral content of forages that can be solved distributing mineral supplements to animals on pasture rich in Ca, P and Mg, and free of K and Fe, depending to the different state areas, Mn, Zn and Cu should be added.

El objetivo del estudio fue determinar el contenido de macro y microminerales en tres zonas del estado de Quintana Roo, norte (N), centro (C) y sur (S) y determinar los principales forrajes cultivados por productores de bovinos. Se muestrearon 45 unidades ganaderas de las que se obtuvieron 108 muestras de forrajes y 68 de suelos. Los minerales se determinaron mediante espectrometría de absorción atómica y el P por colorimetría. Las variables se analizaron mediante el procedimiento GLM y los promedios se compararon empleando la prueba de Duncan. Los forrajes encontrados más frecuentemente fueron: Brachiaria brizantha, 73.3%; Cynodon plectostachyus, 31.1 %; Pennisetum purpureum, 31.1 %; Panicum maximun, var Tanzania, 26.6%; P. maximun, var Mombasa, 15.5%; P. maximun, var Guinea, 13.3%; Brachiaria mutica, 11.1%; y Brachiaria humidicola, 11.1%. Se encontraron contenidos bajos de Ca, P y Mg en las pasturas asociadas con un bajo nivel de estos minerales en los suelos, mientras que los contenidos de K y Fe se encontraron en niveles elevados tanto en los forrajes como en los suelos. Asimismo, se encontraron deficiencias zonificadas de Mn (N), Zn (C) y Cu (C y S). Se concluye que existen fuertes desbalances en el contenido de minerales de los forrajes, que pueden ser subsanados aportando a los animales en pastoreo complementos minerales con Ca, P y Mg, libres de K y Fe, y dependiendo de la zona del estado se deberá añadir Mn, Zn y Cu.

Diatoms from lentic and lotic systems in Antioquia, Chocó and Santander Departments in Colombia

In the tropical and subtropical regions, there is a large number of species which has not been yet described. The high possibility of extinction makes their inventory a priority. In this paper, 23 diatoms taxa from Andean lotic systems and lentic waterbodies localized in the Departments of Antioquia, Santander and Chocó, Colombia, are analyzed with light and scanning electron microscopy. Each taxon is described and information about environmental characteristic of the sites where they were collected and distribution in Colombia is given. The studied taxa belong to the orders Thalassiosirales (1), Aulacoseirales (1), Fragilariales (4), Cymbellales (7), Achnanthales (2), Naviculales (7), and Thalassiophysales (1). Fifteen of them are recorded for the first time in Colombia and Encyonema jemtlandicum in South America. A comparison with the diatom flora of the Colombian Amazonia showed that there were only three taxa in common to these two equatorial regions probably due to the influence of altitudinal gradient. Rev. Biol. Trop. 56 (3): 1159-1178. Epub 2008 September 30.

En este artículo se analizan con microscopios de luz y electrónico de barrido 23 taxones de diatomeas provenientes de sistemas lénticos y lóticos andinos localizados en los Departamentos de Antioquia, Santander y Chocó, Colombia. Cada taxon es descrito e ilustrado y se brinda información acerca de su distribución en Colombia y de las condiciones físicas y químicas en las que fueron colectados. Los taxones estudiados pertenecen a los órdenes Thalassiosirales (1), Aulacoseirales (1), Fragilariales (4), Cymbellales (7), Achnanthales (2), Naviculales (7) y Thalassiophysales (1). 15 de ellos son registrados por primera vez para Colombia y Encyonema jemtlandicum es primer registro para América del Sur. Una comparación con la flora diatomológica de la Amazonía Colombiana, mostró que únicamente 3 taxones fueron hallados en ambas regiones, probablemente debido a la influencia de los gradientes altitudinales.

Edaphic and arboricolous oribatid mites (Acari; Oribatida) in tropical environments: changes in the distribution of higher level taxonomic groups in the communities of species

We analysed the community of oribatid mites in 25 environments of northern Brazil and one in a rain forest in Peru, encompassing fauna sampled on natural and artificial (nylon-mesh bags) substrata, from primary and secondary forests, caatinga, savannahs, flooded forests, bark and epiphytes of trees, and polyculture. A hundred and forty six species are definitively identified from a total of 444 taxa. To determine changes in the community, we took as a basis of comparison the species dominance of Lower Oribatida vs. Oppioidea and Lower Oribatida vs. Poronota. Even considering the different periods in which the inventories were realized and the different sampling methodology compared, the partition of the species of Oribatid mite in larger groups shows tendencies indicating partition of species dominance among the environments studied, showing that they differed in their suitability as habitats for the Oribatid mite community, mainly in respect to the Lower Oribatida, Oppioidea and Poronota composition. These tendencies should be explored in more detail as more becomes known about the species composition in each environment.

Analisou-se comunidade de ácaros oribatídeos em 25 ambientes do Norte do Brasil e em uma floresta no Peru, compreendendo fauna de substratos naturais e artificiais (sacos de malha) coletada em florestas primárias, florestas secundárias, caatinga, savanas, florestas inundáveis, casca e epífitas de árvores e policultivo. Cento e quarenta e seis espécies são definitivamente identificadas de um total de 444 taxa. Foram comparadas as dominâncias de espécies de Oribatida Inferior vs. Oppioidea e Oribatida Inferior vs. Poronota para determinar as mudanças na comunidade. Mesmo considerando os diferentes períodos dos inventários e as diferentes metodologias de coleta comparadas, a partição de espécies de Oribatida em grandes grupos mostra tendências que podem ser indicadoras da partição da dominância entre os ambientes estudados, indicando que eles diferiram em suas qualidades como habitat para a comunidade de ácaros oribatídeos, principalmente no que diz respeito à composição dos Oribatida Inferiores, Oppioidea e Poronota. Essas tendências devem ser exploradas com mais detalhes à medida que se conheça mais sobre a composição das espécies em cada ambiente.