Tree structure and diversity of a Humid Mountain Forest in the protected natural area La Martinica, Veracruz, Mexico / Estructura y diversidad arbórea de un bosque húmedo de montaña en el Área Natural Protegida La Martinica, Veracruz, México

Abstract Introduction: The Humid Mountain Forest (HMF) has the highest number of plants per unit of surface, whose vegetation grows under heterogeneous environmental conditions and possess a high floristic variation. HMF conservation is important due to the biodiversity it harbors and the environmental services it provides. Objective: This work evaluated the effect of the terrain aspect and density of the forest canopy on the structure and tree diversity in La Martinica Protected Natural Area, Mexico. Methods: Stratified sampling was performed in four terrain aspects and two canopy density conditions. Twenty five sampling units of 20 x 25 m were considered, in which the normal diameter (ND), total height and the largest and smallest diameters of the crown of the individuals with a ND ≥ 10 cm were registered. The diversity was estimated by rarefaction curves and the structure was analyzed through the importance value index (IVI) and the forest value index (FVI). Results: 37 species belonging to 30 genera and 24 families were recorded. Greater diversity was observed in the north terrain aspect and in the closed canopy. Tree species with the highest structural values were different between terrain aspect and canopy types; Carpinus tropicalis presented the highest values in the zenithal terrain aspect, Lippia myriocephala in the east and south terrain aspect, and Liquidambar styraciflua in the north. In both canopy types Lippia myriocephala obtained the highest IVI values and FVI in the open canopy; Carpinus tropicalis reached a higher FVI in the closed canopy. Conclusions: Tree structure was different in the four terrain aspects and two canopy conditions studied. The greatest difference in species composition and diversity was observed between the north and east terrain aspects; the north presented the highest richness values, frequent and dominant species.

Resumen Introducción: El Bosque Húmedo de Montaña (BHM) posee el mayor número de especies vegetales por unidad de superficie, cuya vegetación se desarrolla en condiciones ambientales muy heterogéneas y presenta una alta variación florística. La conservación del BHM es importante debido a la biodiversidad que alberga y los servicios ambientales que proporciona. Objetivo: Este trabajo evaluó el efecto de la orientación del terreno y la densidad del dosel del bosque sobre la estructura y diversidad arbórea en el Área Natural Protegida La Martinica, México. Métodos: Se efectuó un muestreo estratificado en cuatro orientaciones del terreno y dos condiciones de densidad del dosel; se consideraron 25 unidades de muestreo de 20 x 25 m, en las que se registró: el diámetro normal (DN), la altura total y los diámetros mayor y menor de la copa de los individuos con un DN ≥10 cm. La diversidad se estimó por medio de curvas de rarefacción y la estructura se analizó con el índice de valor de importancia (IVI) y el índice de valor forestal (IVF). Resultados: Se registraron 37 especies pertenecientes a 30 géneros y 24 familias. Se observó una mayor diversidad en la orientación norte y en el dosel cerrado. Las especies arbóreas con valores estructurales más altos fueron diferentes entre orientaciones y tipos de dosel; Carpinus tropicalis presentó los valores más elevados en la orientación cenital, Lippia myriocephala en las orientaciones este y sur, y Liquidambar styraciflua en la norte. En ambos tipos de dosel Lippia myriocephala obtuvo los valores más altos del IVI e IVF en el dosel abierto; Carpinus tropicalis alcanzó un IVF más elevado en el dosel cerrado. Conclusiones: La estructura arbórea fue diferente en las cuatro orientaciones estudiadas y en las dos condiciones del dosel. La mayor diferencia en composición de especies y diversidad se observó entre las orientaciones norte y este, de ellas, la norte presentó los valores más altos de riqueza, especies frecuentes y dominantes.

Diversidad de árboles en cuatro etapas de sucesión ecológica del bosque tropical montano nuboso del altiplano occidental de Guatemala / Diversity of trees in four stages of ecological succesion of the tropical montane cloud forest in Guatemala ́s western plateau

El objetivo de la investigación fue identificar la riqueza de especies de árboles en etapas de sucesión ecoló-gica de áreas perturbadas del ecosistema bosque tropical montano nuboso (btmn) del altiplano occidental de Guatemala. Con el propósito de generar un registro de referencia para promover acciones de restauración ecológica. El btmn provee de agua para consumo humano a diez etnias mayas y población mestiza. La presión por deforestación y cambio de uso de la tierra por demanda de leña, madera, pastoreo y agricultura, ha generado fragmentación y deterioro de su composición y estructura. Se delimitó como área de estudio el territorio de sierra de Los Cuchumatanes y Cadena Volcánica Occidental con cotas superiores a 2,400 m s. n. m. Se seleccionaron 37 sitios con cuatro etapas de sucesión ecológica denominadas de plántula, brinzal, latizal, fustal y bosque maduro. Se evaluó la presencia y densidad de especies de árboles, en transectos de 2 x 50 m, para definir comunidades florísticas para cada etapa de sucesión ecológica. Se encontró una riqueza de 67 especies de árboles en las 16 comunidades florísticas diferenciadas, de ellas 40 especies promisorias para restauración. Significa que el 60% de la diversidad arbórea del btmn es apta para promover acciones efectivas para su restauración, conocimiento clave para reorientar los planes orientados al establecimiento de plantaciones de coníferas con fines maderables que impulsa el estado guatemalteco para restaurar este ecosistema.

The goal in this investigation was to identify the richness species of trees in stages of ecological succesion in perturbed areas of the tropical montane cloud forest (tmcf's) ecosistem in Guatemala ́s western plateau. The intentionally is to generate a reference registration to promote ecological restoration actions, which supply clean water to teen Mayan ethnic groups and mestizo population. However, this forest is being affected due to change of land use for cattle, agriculture, firewood a timber, which has generated fragmentation and deterioration in its composition and structure. The territory of Sierra de los Cuchumatanes and Western Volcanic Chain was de-limited as a study area with dimensions above 2,400 m a. s. l. 37 places with four stages of ecological succession of plantula, brinzal, latizal, fustal and mature forest were selected. The presence and density of trees species was evaluated in 2x50 m transect, to define floristic communities in each stage of ecological succession. In the 16 floristic communities differentiated was found 67 trees species and 40 of them are promising to restoration. This mean that the 60% of the arboreal wealth richness in the tmcf's is suitable to promote effective restoration deeds, this knowledge is the key to update plans to establishment coniferous plantations for timber purposes, promoted by Guatemalan State to assist in the recovery of this ecosystem.

Feeding preference of the shredder Phylloicus sp. for plant leaves of Chrysophyllum oliviforme or Miconia chartacea after conditioning in streams from different biomes / Preferência alimentar do fragmentador Phylloicus sp. por folhas de Chrysophyllum oliviforme e Miconia chartacea após condicionadas em riachos de dois biomas

Abstract Macroinvertebrate shredders consume preferably leaves conditioned by fungi and bacteria which offer greater palatability to them. Plant species in Cerrado present high concentration of chemical elements such as lignin and cellulose, phenols and tanins thus making them less attractive for shredders consumption and limiting the palatability. This study aimed to evaluate the feeding preference of a macroinvertebrate shredder of the genus Phylloicus for plant material from two different biomes (Cerrado and Mata Atlântica), after conditioning in a stream of Mata Atlântica and observing their physical and chemical characteristics. Senescent leaves were collected, monthly from the litterfall of riparian vegetation in a 500 m stretch of a stream in each biome from August 2014 to January 201. The most abundant species in each stream was selected for the experiment. The experimental design consisted in with two treatments. The first (T1) comprised leaf discs from Chrysophyllum oliviforme (Cerrado species) together with leaf discs of Miconia chartacea (Atlantic Forest species) which were conditioned in the Atlantic Forest stream. The second treatment (T2) involved leaf discs of Miconia chartacea conditioned in Mata Altlântica and Cerrado streams. Both tests had showed significant differences between the two treatments (T1 and T2). For T1, there was consumption of M. chartacea leaf discs by Phylloicus sp., but there was no consumption of C. oliviforme discs. For T2, there was preference for M. chartaceae leaves conditioned in a stream of Mata Atlântica than in Cerrado stream. The results showed that Phylloicus sp., had presented preference for food detritus of the Mata Antlântica biome and rejection to the one from Cerrado biome.

Resumo Macroinvertebrados fragmentadores consomem folhas preferencialmente condicionadas por fungos e bactérias que lhes oferece uma maior palatabilidade. Nas espécies do cerrado esse condicionamento está também associado às altas concentrações de elementos químicos limitantes à palatabilidade como alto teor de lignina e celulose, que tornam as folhas menos atrativas para os fragmentadores. O trabalho teve como objetivo avaliar a preferência alimentar de macroinvertebrados fragmentador ( Phylloicus sp.) por material vegetal de dois diferentes biomas (Cerrado e Mata Atlântica), após condicionamento em riacho de Mata Atlântica, observando suas características físicas e químicas. Foram coletadas folhas senescentes do aporte vegetal (AV) de espécies nativas da vegetação ripária nesses dois biomas, com periodicidade mensal em um trecho de 500 m de um córrego em cada bioma. O experimento foi delineado com dois tratamentos. O primeiro (T1) compreendeu discos de folhas do Cerrado (Chrysophyllum oliviforme) mais discos de folhas da Mata Atlântica (Miconia chartacea) que foram condicionadas em córrego de Mata Atlântica. O segundo tratamento (T2) envolveu discos de folhas da Mata Atlântica condicionadas em córrego da Mata Atlântica mais discos de folhas da Mata Atlântica condicionadas em córrego do Cerrado. Os dois testes apontaram diferenças significativas entre os dois tratamentos (T1 e T2). Para T1 houve consumo de discos de folha de M. chartacea por Phylloicus sp, mas não houve consumo dos discos de C. oliviforme , de Cerrado. Para T2, houve o consumo, porém a preferência pelas folhas de M. chartaceae condicionadas no córrego da Mata Atlantica foi consideravelmete maior. Os resultados apontam que Phylloicus sp, apresentou preferência alimentar pelo detrito de bioma de Mata Atlântica e rejeição pelo detrito do bioma Cerrado.

Estructura de la vegetación leñosa en tres áreas con Selva Baja Caducifolia en el Istmo-Costa de Oaxaca, México / Woody vegetation structure in three areas with Tropical Dry Forest in the Isthmus-Coastal of Oaxaca, Mexico

Resumen La Selva Baja Caducifolia (SBC) es de gran importancia por su biodiversidad. En el Istmo-Costa de Oaxaca, México, se encuentran áreas con SBC y distinta categoría de protección (legislación mexicana): (1) Área Natural Protegida (ANP), (2) Área Destinada Voluntariamente para la Conservación (ADVC) y (3) Área de Uso Común (ADUC). En cada una de ellas se analizó la estructura de vegetación leñosa, plantas con DAP ≥ 2.5 cm, muestreando 15 parcelas de 100 m2. La riqueza observada fue de 90 especies incluidas en 36 familias y corresponde al 80 % (Jackknife) y 85 % (ICE) de la esperada. El análisis de agrupamiento identificó dos grupos con 90 % de disimilitud: el primero (G1) incluyó a todas las parcelas muestreadas del ANP; y el segundo (G2) aglomeró las del ADVC y ADUC. Los índices de Shannon, dominancia de Simpson y diversidad verdadera de Jost para el G1 fueron H'= 2.43, D= 0.21 y qD= 11 y para el G2, H'= 2.76, D= 0.28 y qD= 15, sin diferencias entre grupos (P < 0.05). Las especies con Valor de Importancia Relativa más elevado, en ambos grupos, corresponden a vegetación secundaria. La densidad de especies del G1 fue de 1 829 ind/ha y en el G2 de 2 370 ind/ha. Los promedios de altura (6.8 m) y área basal (19.7 m2/ha) del G1 no variaron significativamente (P < 0.05) con los del G2 (7.9 m y 22.1 m2/ha). Las ADVC y ADUC, semejantes en composición y estructura, difieren del ANP. Se sugiere seguir monitoreando la SBC.

Abstract Tropical dry forest (TDF) is important due to its biodiversity. In the Isthmus-Coastal region of the state of Oaxaca, in Southeast Mexico, there are many areas of TDF with varying categories of legal protection (1) Protected Natural Areas (PNA), (2) Voluntarily Designated Conservation Areas (VDCA) and (3) Areas of Common Use (ACU). In each of these, tree vegetation structure was analysed, recording plants with a DBH ≥ 2.5 cm and sampling 15 plots of 100 m2. Observed richness was 90 species, belonging to 36 families and corresponding to 80 % (Jackknife) and 85 % (ICE) of expected richness. A cluster analysis identified two groups with 90 % dissimilitude: the first (G1) included all the sampled plots in the PNA; and the second (G2), grouped together those from the VDCA and the ACU. The Shannon, Simpson dominance and Jost true diversity indices for G1 were H'= 2.43, D= 0.21 and qD= 11 and for G2, H'= 2.76, D= 0.28 and qD= 15 respectively, with no differences between groups (P < 0.05). The species that presented the highest relative importance value (RIV) in both groups, corresponded to secondary vegetation. Species density of G1 was 1 829 ind/ha and 2 370 ind/ha for G2. Mean height (6.8 m) and basal area (19.7 m2/ha) of G1 did not vary significantly (P < 0.05) when compared to G2 (7.9 m y 22.1 m2/ha). The VDCA and ACU presented similar composition and structure, differing from the PNA. Continual monitoring of the TDF is suggested. Rev. Biol. Trop. 66(2): 863-879. Epub 2018 June 01.

Tree community variation in a tropical continental island according to slope aspect and human interference

ABSTRACT Associating description of unrecorded tropical tree community structure to sampling approaches that can help determine mechanisms behind floristic variation is important to further the comprehension of how plant species coexist at tropical forests. Thus, this study had the goals of (i) evaluating tree community structure on the continental island of Marambaia (23°4'37.09"S; 43°59'2.15"W) and (ii) testing the prediction that there are local scale changes in a tropical tree community structure between slopes facing different geographic orientation and with distinct human interference history. We established 60 (0.6 ha) sampling units in three different slope sites with distinct predominant geographic orientation and human interference. We sampled all woody trees with diameter at breast height (dbh) ≥ 5 cm. We found a total of 1.170 individuals representing 220 species, 120 genera and 50 families. The overall tree community structure and structural descriptors (abundance of individuals, basal area, species richness and diversity) varied extensively between the sites. The evidence presented here supports that local scale topography variations and human interference history can be important factors contributing to the known floristic heterogeneity of the Atlantic Rainforest. Future work on the study area should focus on disentangling effects from distinct causal factors over tree community variation and species occurrence.

Sampling procedures for inventory of commercial volume tree species in Amazon Forest

ABSTRACT The spatial distribution of tropical tree species can affect the consistency of the estimators in commercial forest inventories, therefore, appropriate sampling procedures are required to survey species with different spatial patterns in the Amazon Forest. For this, the present study aims to evaluate the conventional sampling procedures and introduce the adaptive cluster sampling for volumetric inventories of Amazonian tree species, considering the hypotheses that the density, the spatial distribution and the zero-plots affect the consistency of the estimators, and that the adaptive cluster sampling allows to obtain more accurate volumetric estimation. We use data from a census carried out in Jamari National Forest, Brazil, where trees with diameters equal to or higher than 40 cm were measured in 1,355 plots. Species with different spatial patterns were selected and sampled with simple random sampling, systematic sampling, linear cluster sampling and adaptive cluster sampling, whereby the accuracy of the volumetric estimation and presence of zero-plots were evaluated. The sampling procedures applied to species were affected by the low density of trees and the large number of zero-plots, wherein the adaptive clusters allowed concentrating the sampling effort in plots with trees and, thus, agglutinating more representative samples to estimate the commercial volume.

Diameter distribution in a Brazilian tropical dry forest domain: predictions for the stand and species

ABSTRACT Currently, there is a lack of studies on the correct utilization of continuous distributions for dry tropical forests. Therefore, this work aims to investigate the diameter structure of a brazilian tropical dry forest and to select suitable continuous distributions by means of statistic tools for the stand and the main species. Two subsets were randomly selected from 40 plots. Diameter at base height was obtained. The following functions were tested: log-normal; gamma; Weibull 2P and Burr. The best fits were selected by Akaike's information validation criterion. Overall, the diameter distribution of the dry tropical forest was better described by negative exponential curves and positive skewness. The forest studied showed diameter distributions with decreasing probability for larger trees. This behavior was observed for both the main species and the stand. The generalization of the function fitted for the main species show that the development of individual models is needed. The Burr function showed good flexibility to describe the diameter structure of the stand and the behavior of Mimosa ophthalmocentra and Bauhinia cheilantha species. For Poincianella bracteosa, Aspidosperma pyrifolium and Myracrodum urundeuva better fitting was obtained with the log-normal function.

Soil-vegetation relationships and community structure in a "terra-firme"-white-sand vegetation gradient in Viruá National Park, northern Amazon, Brazil

ABSTRACT Viruá National Park encompasses a vast and complex system of hydromorphic sandy soils covered largely by the white sand vegetation ("Campinarana") ecosystem. The purpose of this study was to investigate a vegetation gradient of "terra-firme"-white sand vegetation at the Viruá National Park. Nine plots representing three physiognomic units were installed for floristic and phytosociological surveys as well as to collect composite soil samples. The data were subjected to assessments of floristic diversity and similarity, phytosociological parameters and to statistical analyses, focused on principal components (PC) and canonical correspondence analysis (CCA). The vegetation of the Campinaranas types and Forest differed in biomass and species density. Ten species, endemic to Brazil, were particularly well-represented. PC and CCA indicated a clear distinction between the studied plots, based on measured soil variables, especially base sum and clay, which were the most differentiating properties between Campinarana and Forest; For the separation of the Campinarana types, the main distinguishing variable was organic matter content and cation exchange capacity. Higher similarity of Campinaranas was associated to a monodominant species and the lower similarity of Forest was related to the high occurrence of locally rare species.

Floristic-functional variation of tree component along an altitudinal gradient in araucaria forest areas, in Southern Brazil

ABSTRACT We aimed to investigate the taxonomic and functional variations of tree component of Araucaria Forest (AF) areas located along an altitudinal gradient (700, 900 and 1,600 m asl), in the southern region of Brazil. The functional traits determined were leaf area, specific leaf area, wood density, maximum potential height and dispersal syndromes and deciduousness. The data were analyzed through a functional and taxonomic dissimilarity dendrograms, community-weighted mean trait values, parametric and nonparametric tests, and Principal Component Analysis. The largest floristic-structural similarity was observed between the lower altitude areas (700 and 900 m asl), whose Bray-Curtis distance was 0.63. The area at 700 m asl was characterized by a predominance of deciduous and semi-deciduous species, with a high number of self- and wind-dispersed species, whereas the area at 1,600 m asl exhibited a predominance of animal-dispersed and evergreen species. It was also observed that there were significant variations for leaf traits, basic wood density and maximum potential height. Over all altitudinal gradient, the ordinations indicated that there was no evidence of functional differentiation among dispersal and deciduousness groups. In conclusion, the evaluated Araucaria Forest areas presented high floristic-functional variation of the tree component along the altitudinal gradient.

Contribución al conocimiento de los encinos (Quercus: Fagaceae) en los departamentos de Alta Verapaz, Baja Verapaz y Petén, Guatemala / Contribution to the knowledge of oaks (Quercus: Fagaceae) from the departaments of Alta Verapaz, Baja Verapaz and Petén, Guatemala

Las especies del género Quercus son de importancia ecológica y económica dentro de los bosques donde se desarrollan. Pueden encontrarse desde zonas cálidas y secas hasta selvas lluviosas. Estos bosques, también son reconocidos por presentar alto grado de endemismo y gran número de interacciones ecológicas. Sin embargo, en Guatemala las especies de encino han sido poco estudiadas y están fuertemente amenazadas; a pesar de poseer un alto potencial para aprovechamiento, manejo y uso en la restauración de ecosistemas. Este estudio se orientó hacia la actualización de la riqueza y distribución geográfica de las especies de encino para Alta Verapaz, Baja Verapaz y Petén, a partir de la revisión de registros en herbarios nacionales, bases de datos en línea de herbarios extranjeros y colectas de campo. Se registraron 19 especies de encinos en Alta Verapaz, Baja Verapaz y Petén, nueve especies más de las reportadas previamente, actualizándose los rangos de distribución departamental de 18 especies a excepción de Quercus sapotifolia Liebm. De las especies registradas, 16 se encuentran con algún grado de amenaza, según el Listado de Especies Amenazadas y listas rojas de UICN. También se identificaron vacíos de información acerca de la distribución de estas especies dentro de remanentes boscosos importantes en los departamentos evaluados. Se espera que a partir de este estudio se incrementen los esfuerzos por comprenden la riqueza y distribución de las especies de encino para Guatemala.

Quercus species represent one of the genera with ecological and economic importance within the forests where they develop, since these can be found from warm and dry zones to rain forests. Oak forests also exhibit high endemism levels and a large number of ecological interactions. However, oak species in Guatemala have been briefly studied, although they represent a genus highly threatened and with a high potential for use, handling and ecosystem restoration. This study was oriented towards the actualization of richness and geographical distribution of the oak species in Alta Verapaz, Baja Verapaz and Peten from reviewing records in National Herbariums, online databases of foreign Herbariums and field collection. A total of 19 oak species in Alta Verapaz, Baja Verapaz and Peten were recorded, nine more species of those previously reported, updating the departmental distribution ranges of 18 species except Quercus sapotifolia Liebm. Of the species recorded, 16 were listed with some degree of threat according to the national List of Threatened Species and the IUCN Red List of Threatened Species. Our results evidenced that the oak species were located in important forest remnants in all of the departments evaluated. It is expected from this study to increase the efforts to understand the oak species richness and species distributions patterns for Guatemala.

Calibration of the maximum carboxylation velocity (Vcmax) using data mining techniques and ecophysiological data from the Brazilian semiarid region, for use in Dynamic Global Vegetation Models / Calibração da velocidade máxima de carboxilação (Vcmax), utilizando técnicas de mineração de dados e dados de ecofisiologia da região semiárida brasileira, para uso em Modelos de Vegetação Globais Dinâmicos

Abstract The semiarid region of northeastern Brazil, the Caatinga, is extremely important due to its biodiversity and endemism. Measurements of plant physiology are crucial to the calibration of Dynamic Global Vegetation Models (DGVMs) that are currently used to simulate the responses of vegetation in face of global changes. In a field work realized in an area of preserved Caatinga forest located in Petrolina, Pernambuco, measurements of carbon assimilation (in response to light and CO2) were performed on 11 individuals of Poincianella microphylla, a native species that is abundant in this region. These data were used to calibrate the maximum carboxylation velocity (Vcmax) used in the INLAND model. The calibration techniques used were Multiple Linear Regression (MLR), and data mining techniques as the Classification And Regression Tree (CART) and K-MEANS. The results were compared to the UNCALIBRATED model. It was found that simulated Gross Primary Productivity (GPP) reached 72% of observed GPP when using the calibrated Vcmax values, whereas the UNCALIBRATED approach accounted for 42% of observed GPP. Thus, this work shows the benefits of calibrating DGVMs using field ecophysiological measurements, especially in areas where field data is scarce or non-existent, such as in the Caatinga.

Resumo A região semiárida do nordeste do Brasil, a Caatinga, é extremamente importante devido à sua biodiversidade e endemismo. Medidas de fisiologia vegetal são cruciais para a calibração de Modelos de Vegetação Globais Dinâmicos (DGVMs) que são atualmente usados para simular as respostas da vegetação diante das mudanças globais. Em um trabalho de campo realizado em uma área de floresta preservada na Caatinga localizada em Petrolina, Pernambuco, medidas de assimilação de carbono (em resposta à luz e ao CO2) foram realizadas em 11 indivíduos de Poincianella microphylla, uma espécie nativa que é abundante nesta região. Estes dados foram utilizados para calibrar a velocidade máxima de carboxilação (Vcmax) usada no modelo INLAND. As técnicas de calibração utilizadas foram Regressão Linear Múltipla (MLR) e técnicas de mineração de dados como Classification And Regression Tree (CART) e K-MEANS. Os resultados foram comparados com o modelo INLAND não calibrado. Verificou-se que a Produtividade Primária Bruta (PPB) simulada atingiu 72% da PPB observada ao usar os valores de Vcmax calibrado, enquanto que o modelo não calibrado obteve-se 42% da PPB observada. Assim, este trabalho mostra os benefícios de calibrar DGVMs usando medidas ecofisiológicas de campo, especialmente em áreas onde os dados de campo são escassos ou inexistentes, como na Caatinga.

Characterization saprobic fungi on leaf litter of two species of trees in the Atlantic Forest, Brazil

Abstract We investigated the composition and structure of fungal communities associated with leaf litter generated by Clusia nemorosa and Vismia guianensis that belong to phylogenetically-related botanical families and exist together in a remnant of the Atlantic Forest in Bahia, Brazil. Samplings were conducted during wet (June 2011) and dry (January 2013) seasons in Serra da Jibóia. The fungi were isolated using particle filtration and the 1,832 isolates represented 92 taxa. The wet season yielded the largest number of isolates (1,141) and taxa (76) compared with the dry season (641 isolates and 37 taxa). The richness and diversity of fungal species associated with C. nemorosa (64 taxa, Simpson=0.95)were higher compared with those of V.guianensis (59 taxa, Simpson =0.90). Analysis of similarity (ANOSIM) revealed significant variations in the composition and community structure of fungi isolated from the two plants as a function of seasons. In contrast, nonmetric multidimensional scaling (NMDS) analysis show that the seasonality was an important influence on the distribution of fungal species. However, the populations of the saprobic fungal communities were dynamic, and several factors may influence such communities in the Atlantic Forest.

Updated List and identification key of 219 tree species of white sand forests of the Allpahuayo Mishana National Reserve, Loreto, Peru / Lista actualizada y clave para la identificación de 219 especies arbóreas de los bosques sobre arena blanca de la Reserva Nacional Allpahuayo Mishana, Loreto, Perú

Los bosques sobre arena blanca, aunque bajo en nutrientes, se caracterizan por presentar no solo varias especies endémicas sino también varias especies monodominantes. En general, las plantas en este tipo de bosque presentan fustes notoriamente delgados. El objetivo del presente trabajo fue elaborar una clave dicotómica paralela para la identificación de las especies de Angiospermas arbóreas de los bosques sobre arena blanca de la Reserva Nacional Allpahuayo Mishana, Loreto, Perú. Para la elaboración de la lista de especies que ocurren en los bosques sobre arena blanca se hizo una revisión bibliográfica. Se encontraron 219 especies de Angiospermas, las especies con mayor porcentaje de individuos fueron: Pachira brevipes (26.27%), Caraipa utilis (17.90%), Dicymbe uaiparuensis (13.27%), Dendropanax umbellatus (3.28%), Sloanea spathulata (2.52%), Ternstroemia klugiana (2.30%), Haploclathra cordata (2.28%), Parkia igneiflora (1.20%), Emmotum floribundum (1.06%), Ravenia biramosa (1.04%) entre otras. La mayoría de las especies de los bosques sobre arena blanca pueden ser diferenciadas utilizando características de los tallos, ramas y hojas. Esta clave es de mucha utilidad para el desarrollo de inventarios florísticos y otros proyectos afines en los bosques sobre arena blanca de la Reserva Nacional Allpahuayo Mishana.

White sand forests, although low in nutrients, are characterized not only by several endemic species of plants but also by several monodominant species. In general, plants in this forest have noticeably thin stems. The aim of this work was to elaborate a parallel dichotomous key for the identification of Angiosperm tree species occurring on white sand forests at the Allpahuayo Mishana National Reserve, Loreto, Peru. We compiled a list of species from several publications in order to have the most comprehensive list of species that occur on white sand forest. We found 219 species of Angiosperm, the more abundant species were Pachira brevipes (26.27%), Caraipa utilis (17.90%), Dicymbe uaiparuensis (13.27%), Dendropanax umbellatus (3.28%), Sloanea spathulata (2.52%), Ternstroemia klugiana (2.30%), Haploclathra cordata (2.28%), Parkia igneiflora (1.20%), Emmotum floribundum (1.06%), Ravenia biramosa (1.04%) among others. Most species of white sand forests can be distinguished using characteristics of stems, branches and leaves. This key is very useful for the development of floristic inventories and related projects on white sand forests from Allpahuayo Mishana National Reserve.

Complejidad estructural de los manglares de Playa Blanca, Escondido y Rincón de Osa, Golfo Dulce, Costa Rica / Structural complexity of mangroves in Playa Blanca, Escondido and Rincón de Osa, Golfo Dulce, Costa Rica

Resumen Este estudio reporta las características estructurales y distribución de las especies en los bosques de mangle de Playa Blanca, Escondido y Rincón en Golfo Dulce, Pacífico Sur de Costa Rica. Se realizaron múltiples transectos en cada uno de los manglares. Cada 10m a lo largo de cada transecto se delimitaron parcelas cuadradas de 5x5m. En cada parcela se midió el diámetro a la altura del pecho y altura de los árboles de mangle y se tomaron muestras de sedimento y de agua intersticial (salinidad). Se determinó la densidad total y por especie para cada manglar, el área basal y valor de importancia por especie y la complejidad general entre los manglares. Las especies dominantes en los tres manglares estudiados fueron Rhizophora racemosa y Pelliciera rhizophorae. Los manglares de Playa Blanca y Rincón presentaron mayor similitud en la estructura del bosque entre sí que con el manglar de Escondido. Playa Blanca fue el bosque de mayor altura del dosel y menor densidad; mientras que Escondido presentó mayor densidad y menor altura, así como el menor número de especies y el único donde se encontró la especie Conocarpus erectus. La composición de especies presente en estos manglares coincide con la reportada para la región. Sin embargo, la variación en estructura y complejidad entre los tres manglares es mayor a las similitudes con otros de la región. El estudio histórico y topográfico de estos manglares puede aclarar las variaciones en estructura y complejidad encontrada actualmente entre ellos.

Abstract This study reports the structural characteristics and distribution of species in the mangrove forests of Playa Blanca, Escondido and Rincón de Osa in Golfo Dulce, South Pacific of Costa Rica. Multiple lineal transects were carried out at each of the mangrove forests. Every 10 meters along each transect the diameter at breast height, basal area, and height was determined for all mangrove trees within a 5x5meter square plot. Sediment and interstitial water (salinity) samples were also collected at each plot. Total density of the stand was determined, as were the density of each mangrove species, the importance value and basal area per species, and general complexity indices for each mangrove forest. The dominant species at all three mangroves were Rhizophora racemosa and Pelliciera rhizophorae. Forest structure was more similar between Playa Blanca and Rincón mangroves than with Escondido. Playa Blanca was the forest with the tallest canopy height and lowest density, while Escondido had the highest density and the shortest canopy height. Escondido was also the forest with the least number of species and the only one where Conocarpus erectus was present. Species composition and dominance at these mangroves coincides with that reported for the region. However, the variation in structure and complexity among the three mangroves is greater than the commonalities with mangroves in the region. Topographical and historical analysis of these mangroves could further elucidate the present structure and complexity variation among them. Rev. Biol. Trop. 63 (Suppl. 1): 199-208. Epub 2015 April 01.

Seasonality effect on the allelopathy of cerrado species / Efeito da sazonalidade sobre a alelopatia de espécies de cerrado

The Brazilian cerrado presents strong climate seasonality. During the dry season, plants may be exposed to stressful situations, such as a soil surface water deficit, that stimulate their chemical defenses. However, the seasonality effect on the production of allelopathic compounds of cerrado plant species is poorly understood. In this study, the phytotoxic activities of common native cerrado plants were evaluated during rainy and dry seasons. Crude leaves extracts (10% concentration: weight/volume, with dry leaves and distilled water) from eleven species were tested on lettuce and sesame germination. The negative effects on germination percentages, rates and informational entropies of the target species were higher when submitted to plant extracts from the dry season, where the germination rate was the most sensible parameter. The higher sensibility of lettuce and the germination rate parameter showed this difference. Only two exceptions had higher effects for rainy season extracts; one species showed higher negative effects on germination informational entropy of lettuce and another species on the germination rate of sesame. Thus, increases in the allelopathic activity were seen in the majority of the studied cerrado plant species during the dry season. These distinct responses to stressful situations in a complex environment such as the Brazilian cerrado may support the establishment and survival of some species.

O cerrado brasileiro apresenta forte sazonalidade climática. Durante a estação seca as plantas podem estar expostas a situações estressantes, tais como um déficit de umidade nas camadas superficiais do solo, que estimulam suas defesas químicas. No entanto, o efeito da sazonalidade na produção de compostos alelopáticos de espécies vegetais de cerrado é pouco conhecido. Neste estudo, as atividades fitotóxicas de plantas nativas comuns de cerrado foram avaliadas durante as estações chuvosa e seca. Extratos brutos de folhas (concentração 10%: peso/volume, com folhas secas e água destilada) de onze espécies foram testados sobre a germinação de alface e gergelim. Os efeitos negativos sobre as porcentagens de germinação, velocidades e entropias informacionais das espécies-alvo foram maiores quando submetidas a extratos vegetais da estação seca. A maior sensibilidade da alface e do parâmetro velocidade de germinação mostraram essa diferença. Apenas duas exceções tiveram maiores efeitos para extratos da estação chuvosa; uma espécie mostrou maiores efeitos negativos sobre a entropia informacional de germinação de alface e outra espécie sobre a velocidade de germinação de gergelim. Assim, aumentos na atividade alelopática foram vistos na maioria das espécies vegetais do cerrado estudadas durante a estação seca. Estas respostas distintas a situações estressantes em um ambiente complexo como o cerrado brasileiro podem auxiliar no estabelecimento e na sobrevivência de algumas espécies.

Impact of forest fragment size on the population structure of three palm species (Arecaceae) in the Brazilian Atlantic Rainforest / Impacto del tamaño del fragmento de bosque en la estructura de la población de tres especies de palmas del Bosque Atlántico Brasileño

The main threats to natural populations in terrestrial ecosystems have been widly recognized to be the habitat fragmentation and the exploitation of forest products. In this study, we compared the density of the populations and the structure of three tropical palm species, Astrocaryum aculeatissimum, Euterpe edulis and Geonoma schottiana. For this, we selected five forest fragments of different sizes (3 500ha, 2 400ha, 57ha, 21ha and 19ha) where palms were censused in nine 30x30m plots. We tracked the palms survival from 2005 to 2007, and recorded all new individuals encountered. Each individual was assigned in one of the five ontogenetic stages: seedling, infant, juvenile, immature and reproductive. The demographic structure of each palm species was analyzed and compared by a generalized linear model (GLM). The analysis was performed per palm spe-cies. The forest fragment area and the year of observation were explanatory variables, and the proportion of individuals in each ontogenetic class and palm density were response variables. The total number of individuals (from seedlings to reproductives, of all species) monitored was 6 450 in 2005, 7 268 in 2006, and 8 664 in 2007. The densities of two palm species were not influenced by the size of the fragment, but the population density of A. aculeatissimum was dependent on the size of the fragment: there were more individuals in the bigger than in the smaller forest fragments. The population structure of A. aculeatissimum, E. edulis, and G. schottiana was not altered in the smaller fragments, except the infants of G. schottiana. The main point to be drawn from the results found in this study is that the responses of density and population structure seem not to be dependent on fragment size, except for one species that resulted more abundant in bigger fragments.

Uno de los principales riesgos que corren las poblaciones naturales de los ecosistemas terrestres es la fragmentación de hábitat y la explotación de los recursos forestales. Aquí hemos comparado la densidad de las poblaciones y el estado estructural de tres especies de palmeras, Astrocaryum aculeatissimum (Schott) Burret, Euterpe edulis Mart. y Geonoma schottiana Mart., en fragmentos de diferente tamaño. Las palmas fueron censadas en nueve cuadrantes de 30x30m en cinco fragmentos de bosque de diferente tamaño (3 500ha, 2 400ha, 57ha, 21ha y 19ha). Realizamos el seguimiento de la sobrevivencia de las palmas entre 2005-2007, y registramos todos los nuevos individuos encontrados. Cada individuo fue designado dentro de alguno de los siguientes cinco estadíos ontogenéticos: plántula, infantil, juvenil, inmaduro y reproductivo. La comparación de la estructura demográfica fue analizada usando Modelos Lineares Generalizados (GLM). Estos fueron utilizados para cada especie por separado, con el área del fragmento de bosque y el año como variables explicativas, así como proporción de individuos en cada estadío ontogenético y densidad de las palmeras como variables de respuesta. El número total de individuos monitoreado (desde semillas hasta adultos reproductivos, para todas las especies) fue 6 450 en 2005, 7 268 en 2006 y 8 664 en 2007. La densidad de población para dos especies de palmas no fue influenciada por el tamaño del fragmento, excepto para Astrocaryum aculeatissimum, cuya densidad dependió del tamaño del fragmento. Hubo más individuos en los fragmentos mayores que en los fragmentos menores. La estructura de la población de A. aculeatissimum, E. edulis y G. schottiana no se vio alterada en los fragmentos pequeños, excepto para G. schottiana en estado infante. El punto principal que se desprende de los resultados encontrados en este estudio es que la respuesta de la densidad y estructura de la población parece no ser dependiente del tamaño de fragmento, excepto para una especie que es más abundante en los fragmentos mayores.

Circumscribing campo rupestre – megadiverse Brazilian rocky montane savanas / Circunscrevendo campo rupestre – savanas montanas rochosas megadiversas do Brasil

Currently campo rupestre (CR) is a name accepted and used internationally by botanists, zoologists, and other naturalists, usually applied to a very specific ecosystem, despite the lack of a consensual published circumscription. We present a tentative geographic circumscription of the term, combining data on climate, geology, geomorphology, soil, flora, fauna and vegetation. The circumscription of campo rupestre proposed herein is based on the following premises: (1) the classification of vegetation is not an exact science, and it is difficult to attain a high degree of consensus to the circumscription of vegetation names; (2) despite this, vegetation classification is useful for conservation and management. It is thus desirable to circumscribe vegetation types with the greatest attainable precision; (3) there is a need to preserve all montane and rocky vegetation types, regardless of classification, biome, etc; (4) the CRs are formed by a complex mosaic of vegetation types including rock-dwelling, psammophilous, aquatic, epiphytic, and penumbral plant communities. Campos rupestres stricto sensu are a Neotropical, azonal vegetation complex endemic to Brazil, forming a mosaic of rocky mountaintop “archipelagos” inserted within a matrix of zonal vegetation, mainly in the Cerrado and Caatinga provinces of the Brazilian Shield (southeastern, northeastern and central-western regions), occurring mainly above 900 m asl. up to altitudes exceeding 2000 m, having measured annual precipitation between 800 and 1500 mm, and an arid season of two to five months.

Atualmente campo rupestre (CR) é um termo aceito e internacionalmente usado por botânicos, zoólogos e outros naturalistas, geralmente aplicado a um ecossistema muito específico apesar de não haver uma circunscrição de consenso. Nós apresentamos uma ciscunscrição geográfica tentativa do termo, combinando dados de clima, geologia, geomorfologia, solo, flora, fauna e vegetação. A circunscrição de campo rupestre aqui proposta se baseia nas seguintes premissas: (1) a classificação da vegetação não é uma ciência exata e é difícil atingir um alto grau de consenso sobre a circunscrição de nomes de vegetação; (2) apesar disto, a classificação da vegetação é útil para conservação e manejo. Assim é desejável descrever os tipos de vegetação com a maior precisão tangível; exista a necessidade de se preservar todos os tipos de vegetação montanos e rochosos, independentemente de sua classificação, bioma, etc. (4) os CRs são formados por um complexo mosaico de tipos de vegetação incluindo comunidades sobre rocha, psamíóilas, aquáticas, epífitas e penumbrais. Os campos rupestres stricto sensu são um complexo de vegetação endêmico ao Brasil, azonal, Neotropical, inserido numa matriz de vegetação zonal, sobretudo nas províncias do Cerrado e da Caatinga do Escudo do Brasil (regiões Sudeste, Nordeste e Centro_Oeste), ocorrendo principalmente acima de 900 m de altitude, até altitudes superiores a 2000 m, tendo uma precipitação anual mensurada entre 800 e 1500 mm, e uma estação árida de dois a cinco meses.

Structure of arboreal and herbaceous strata in a neotropical seasonally flooded monodominant savanna of Tabebuia aurea / Estrutura do estrato arbóreo e herbáceo em uma savana neotropical monodominante sazonalmente inundada de Tabebuia aurea

Large areas in the Pantanal wetland are covered by monodominant formations, e.g. typical landscapes with local names such as “paratudal”, dominated by T. aurea. Studies on structure of these formations generally include only woody strata, consequently the species richness registered is usually low due to the absence of the ‘ground layer’ of herbaceous and others low species. We recorded 13 species, 12 genera and 11 families for the arboreal stratum. Considering arboreal flora without the dominant (T. aurea) individuals showed great establishment in relation to the flood level between 35 – 45 cm while the individuals of the dominant species of 30 – 45 cm. The diameter distribution revealed that the population of T. aurea did not show the reverse J curve, the usual pattern for species in constant regeneration, also evidenced in inconstant Licourt quotient, indicating an episodic recruitment that could lead to future changes in structure. In the herbaceous strata we recorded 78 species, included in 62 genera and 27 families. Using plots method we sampled 46 species, 40 genera and 22 families, while in line interception we found 65 species distributed in 57 genera and 26 families. The floristic similarity of Sørensen between both methods was 59.4%, with 33 species in common, and the method of line interception was more efficient in detecting richness, with 35% more species found in the same time. According to the methods of plots and line interception applied on the woody stratum, our results gave similar detailed information on the structure of this type of savanna, and in spite of being monodominant it shows high species richness when the herbaceous stratum is taken into account. Plots and line interception methods showed similar results for the woody stratum and high species richness of the herbaceous stratum.

Amplas áreas no Pantanal são cobertas por formações monodominantes, tipicamente com nomes locais como “paratudal” dominado por Tabebuia aurea. Estudos na estrutura dessas formações geralmente incluem somente estrato arbóreo, consequentemente, a riqueza de espécies detectada geralmente é baixa devido à ausência do “estrato terrestre” das herbáceas e outras poucas espécies. Nós registramos 13 espécies, 12 gêneros e 11 famílias para o estrato arbóreo. Considerando a flora arbórea sem a espécie dominante (T. aurea) apresentaram um ótimo de estabelecimento em relação ao nível de inundação entre 35 – 45cm, enquanto os indíviduos da espécie dominante de 30 – 45cm. A distribuição diamétrica revelou que a população de T. aurea não apresentou o J reverso, o modelo usual para espécies em constante regeneração, também evidenciado pela não constante no quoeficiente de Licourt. Indicando episódio de recrutamento que poderia levar a futuras mudanças na estrutura. Para o estrato herbáceo geral registramos 78 espécies, incluindo 68 gêneros e 27 famílias. Usando o método de parcelas amostramos 46 espécies, 40 gêneros e 22 famílias, enquanto na interseção na linha nós encontramos 65 espécies distribuídas em 57 gêneros e 26 famílias. A similaridade florísitca de Sørensen entre ambos métodos foi de 59,4%, com 33 espécies em comum, e o método de interseção na linha foi mais eficiente na detecção da riqueza, 35% das espécies foram encontradas no mesmo tempo. De acordo com os métodos de parcelas e interseção na linha aplicado no estrato arbóreo, os nossos resultados deram uma semelhante informação detalhada na estrutura deste tipo de savana, e que apesar de ser monodominante mostrou alta riqueza de espécies quando o estrato herbáceo é levado em conta. Os métodos de parcelas e interseção na linha mostraram resultados similares para o estrato arbóreo e alta riqueza de espécies do estrato herbáceo.

Relaciones suelo-vegetación en una toposecuencia del Escudo Guayanés, Venezuela

The Guayana Shield is one of the oldest territories in the planet and has millions of years subjected to leaching and erosion processes that produce oligotrophic soils. This scarcity of nutrients has not avoided the development of high, diverse and magnificent forests, where plants have adaptations to survive these difficult conditions. The aim of this work was to characterize the physical and chemical parameters of the soils in different forest communities of the Imataca Forest Reserve (IFR), to establish some interpretations on their origin, and some relationships between the edaphic components and the inhabitant species. Terrestrial journeys were carried out and two path-ways were traced for the interpretation of forest communities. In each community, three plots (100m x 100m) for the ecological survey were established. In each plot, all trees, palms, and lianas were measured (dbh≥10cm; dbh: diameter at breast height); four 10m x 10m understory sub-plots were evaluated, and a census of all the spermatophyta species (dbh<10cm) was made. Soils were evaluated by means of a trial pit in each community, and a bore in each one understory sub-plot. The obtained data were analyzed by both a detrended and a canonical correspondence analysis. Results from a total of 15 plots allowed us to identify three communities: a forest dominated by Mora excelsa located in a narrow valley with high content of silt; a swamp forest dominated by Catostemma commune in a sandy broad valley, and a forest in clay hills dominated by Alexa imperatricis. Most of the soils had a pH between 3.1 and 4.5. Nutrients were in very low concentrations (N: 0-0.2%; P: 0-14ppm; K: 0-0.3Cmol/kg) and Al in toxicity quantities. We observed that Ca/Al relationship greater than 1 meant a neutralization of the toxic effect of Al. Besides, basal area ranged from 20.4 to 32.3m²/ha; the highest level (top local forest development) corresponded with the C. commune community with a Ca/Al value of 2.5. This research found an adequate relationship between soil and vegetation, as it was able to identify three communities into three distinct soil conditions. Nevertheless, edaphic constraints indicated that high forest cover must be maintained as an essential element for the conservation of these communities.

El Escudo Guayanés es uno de los territorios más antiguos del planeta; tiene millones de años sometido a procesos de lixiviación y erosión que dejan suelos oligotróficos. El objetivo de este trabajo fue hacer la caracterización de los parámetros físicos y químicos de los suelos, en diferentes comunidades boscosas de la Reserva Forestal Imataca, e identificar ciertas relaciones entre los componentes edáficos y las especies que allí se presentan. Se realizó un inventario de todos los individuos mayores a 10cm dap (diámetro a la altura del pecho) en 15 parcelas (1ha); en cada una de esas parcelas se evaluaron cuatro sub-parcelas de sotobosque (100m²) para contabilizar todas las espermatofitas; los suelos se evaluaron mediante una calicata por comunidad y un barreno en cada sub-parcela de sotobosque. La mayoría de los suelos tienen un pH muy ácido (3.1-4.5), los nutrientes están en concentraciones muy bajas (N: 0-0.2%; P: 0-14ppm; K: 0-0.3Cmol/kg) y el Al en concentraciones tóxicas. Esto coincide con otros estudios realizados en esta región, pero en este trabajo se encontró que la relación Ca/Al con valores superiores a 1, lo que implica una neutralización del efecto tóxico del Al y permite un mejor desarrollo de las comunidades boscosas.

Patrones de distribución de especies arbóreas de dosel y sotobosque a escala local en bosques de tierra firme, Amazonia colombiana / Distribution patterns of canopy and understory tree species at local scale in a Tierra Firme forest, the Colombian Amazonia

The effect of environmental variation on the structure of tree communities in tropical forests is still under debate. There is evidence that in landscapes like Tierra Firme forest, where the environmental gradient decreases at a local level, the effect of soil on the distribution patterns of plant species is minimal, happens to be random or is due to biological processes. In contrast, in studies with different kinds of plants from tropical forests, a greater effect on floristic composition of varying soil and topography has been reported. To assess this, the current study was carried out in a permanent plot of ten hectares in the Amacayacu National Park, Colombian Amazonia. To run the analysis, floristic and environmental variations were obtained according to tree species abundance categories and growth forms. In order to quantify the role played by both environmental filtering and dispersal limitation, the variation of the spatial configuration was included. We used Detrended Correspondence Analysis and Canonical Correspondence Analysis, followed by a variation partitioning, to analyze the species distribution patterns. The spatial template was evaluated using the Principal Coordinates of Neighbor Matrix method. We recorded 14 074 individuals from 1 053 species and 80 families. The most abundant families were Myristicaceae, Moraceae, Meliaceae, Arecaceae and Lecythidaceae, coinciding with other studies from Northwest Amazonia. Beta diversity was relatively low within the plot. Soils were very poor, had high aluminum concentration and were predominantly clayey. The floristic differences explained along the ten hectares plot were mainly associated to biological processes, such as dispersal limitation. The largest proportion of community variation in our dataset was unexplained by either environmental or spatial data. In conclusion, these results support random processes as the major drivers of the spatial variation of tree species at a local scale on Tierra Firme forests of Amacayacu National Park, and suggest reserve´s size as a key element to ensure the conservation of plant diversity at both regional and local levels.

El efecto de la variación ambiental en la estructura de las comunidades arbóreas en bosques tropicales, aún se debate. En paisajes como los bosques de tierra firme, donde el gradiente ambiental disminuye, el efecto de los suelos sobre los patrones de distribución de especies es mínimo. En contraste, un mayor efecto de la variación edáfica y topográfica sobre la composición florística, se ha reportado en estudios con diferentes tipos de plantas en bosques tropicales. Este estudio se realizó en diez hectáreas de una parcela permanente. Se evaluó el efecto de la variación ambiental y la configuración espacial sobre los patrones florísticos de las especies arbóreas a escala local, según el estado de desarrollo y categorías de abundancia relativa. Se registraron 14 074 individuos de 1 053 especies y 80 familias. Los suelos son ácidos, presentan altas concentraciones de Aluminio y son predominantemente arcillosos. La diversidad beta fue baja. Las diferencias florísticas explicadas fueron asociadas con procesos biológicos espacialmente estructurados, particularmente, con la limitación en dispersión. Aunque, la mayor parte de la variación no fue explicada por las variables consideradas. Estos resultados sugieren que procesos aleatorios son determinantes esenciales de la variación florística en bosques de tierra firme de la amazonia.