Dynamic and growth of the forests of the Isla del Coco National Park, Costa Rica

Introduction: Islands are essential for world biodiversity. Isla del Coco National Park is an oceanic island in which a tropical rain forest grows; however, its ecology and the effect of introduced species are poorly understood. Objective: To evaluate the mortality, recruitment, regeneration, and growth of forest canopy species. Methods: We measured 15 permanent sampling plots (PSP), nine in the Premontane Pluvial Rainforest (PPR), and six in the Cloud Forest (CF); trees with DBH > 5 cm (diameter at breast height) were measured. The sampling regeneration was done within every PSP, along two transects of 1 X 50 m. Data analyses were performed using data obtained in 2006 and 2012 as baseline. Results: In the period 2012-2017, the annual mortality rate in the PPR was 5.75 % and for CF 6.31 %. The yearly recruitment rate in the PPR was 5.38 %, and 5.90 % for CF. For the PPR the total registered regeneration was 5 656 individuals and 8 700 for the CF. Sacoglottis holdridgei reported the highest mortality and the lowest values of recruitment and regeneration. Forest structure fits the inverted J model for most of the tropical forests. Sacoglottis holdridgei define the forest population structure above DBH > 20 cm. But, diameters under 20 cm are strongly influenced byH. succosa , because it reported the highest abundance of regeneration and recruitment. The annual average increase in diameter between forest was statically different (p = 0.0414; N = 15), 0.36 cm/year in the PPR, and 0.33 cm/year the in CF. Conclusions: The PPR and CF differ in the patterns of mortality, recruitment, and regeneration, confirming the uniqueness of these ecosystems. More successful regeneration ofH. succosawill lead to changes in structure and composition of forests, mainly PPR. The changes in forest structure will have a strong impact on epiphytic flora, microclimate conditions, and bird nesting such asGygis alba(White Tern) due to the loss of mature trees ofSacoglottis. The low regeneration ofS. holdridgeiis associated with the presence of introduced herbivores,their management is needed for restoring the forest.

Introducción: Las islas son esenciales para la biodiversidad mundial. El Parque Nacional Isla del Coco es una isla oceánica cubierta de bosques lluviosos tropicales; sin embargo, su ecología y el efecto de las especies introducidas son poco conocidos. Objetivo: Evaluar la mortalidad, el reclutamiento, la regeneración y el crecimiento de las especies arbóreas. Métodos: Se midieron 15 parcelas permanentes de muestreo (PPM), nueve en el bosque pluvial premontano (BPP) y seis en el bosque nuboso (BN); Se midieron árboles con DAP > 5 cm. El muestreo regeneración se realizó dentro de cada PPM, mediante dos transectos de 1 x 50 m. Los datos se analizaron tomando como línea base las mediciones del 2006, 2012 y 2017. Resultados: En el período 2012-2017, la tasa de mortalidad anual en el BPP fue de 5,75 % y para el BN de 6,31 %. La tasa de reclutamiento anual en el BPP fue de 5.38 % y 5.90 % para BN. Para el BPP, la regeneración total registrada fue de 5 656 individuos y 8 700 para el BN. Sacoglottis holdridgeituvo la mortalidad más alta y los valores más bajos de reclutamiento y regeneración. La estructura del bosque se ajusta al modelo J invertido para la mayoría de los bosques tropicales.Sacoglottis holdridgeidefine la estructura del bosque sobre diámetros > 20 cm. Pero, en diámetros < 20 cm está fuertemente influenciado porH. succosa , especie que reportó la mayor abundancia de regeneración y reclutamiento. El aumento promedio anual del diámetro entre bosques fue estadísticamente diferente (p = 0.0414; N = 15), 0.36 cm/año en el PPR y 0.33 cm/año en el CF. Conclusiones: El BPP y el BN difieren en los patrones de mortalidad, reclutamiento y regeneración, lo que confirma la singularidad de estos ecosistemas. Una regeneración más exitosa deH. Succosa provocará cambios en la estructura y composición de los bosques, principalmente BPP. Los cambios en la estructura del bosque tendrán un fuerte impacto en la flora epífita, las condiciones de microclima y la anidación de aves como Gygis alba(Palomita del Espíritu Santo) debido a la pérdida de árboles maduros de Sacoglottis . La baja regeneración deS. holdridgeiestá asociada con la presencia de herbívoros introducidos, para restaurar el bosque es necesario su manejo.

Post-fire regeneration in seasonally dry tropical forest fragments in southeastern Brazil

ABSTRACT Seasonally dry tropical forest is one of the highly threatened biome. However, studies on the effect of fire on these tree communities are still scarce. In this context, a floristic and structural survey in three forest areas in the southeast of Brazil that were affected by fire between 14 and 25 years ago was performed with the objective of evaluating post-fire regeneration. In each site, five systematically placed plots (25 m x 25 m each) were established. The more recently burnt site had significantly lower values of richness and diversity than the other two sites. However, the sites did not differ in density and basal area. Annona dolabripetala, Astronium concinnum, Joannesia princeps and Polyandrococos caudescens were within the 10 most important species for the three sites. Comparing these data with adjacent mature forests, the results indicated differences both in structural and floristic aspects, suggesting that the time after fire was not sufficient for recuperation of these areas. The recovery process indicate at least 190 years for areas return to basal area values close to those observed in mature forests nearby.

Floristic and structure of an Amazonian primary forest and a chronosequence of secondary succession / Florística e estrutura de uma floresta primária e uma cronossequência de sucessão secundária na Amazônia

The analysis of changes in species composition and vegetation structure in chronosequences improves knowledge on the regeneration patterns following land abandonment in the Amazon. Here, the objective was to perform floristic-structural analysis in mature forests (with/without timber exploitation) and secondary successions (initial, intermediate and advanced vegetation regrowth) in the Tapajós region. The regrowth age and plot locations were determined using Landsat-5/Thematic Mapper images (1984-2012). For floristic analysis, we determined the sample sufficiency and the Shannon-Weaver (H'), Pielou evenness (J), Value of Importance (VI) and Fisher's alpha (α) indices. We applied the Non-metric Multidimensional Scaling (NMDS) for similarity ordination. For structural analysis, the diameter at the breast height (DBH), total tree height (Ht), basal area (BA) and the aboveground biomass (AGB) were obtained. We inspected the differences in floristic-structural attributes using Tukey and Kolmogorov-Smirnov tests. The results showed an increase in the H', J and α indices from initial regrowth to mature forests of the order of 47%, 33% and 91%, respectively. The advanced regrowth had more species in common with the intermediate stage than with the mature forest. Statistically significant differences between initial and intermediate stages (p<0.05) were observed for DBH, BA and Ht. The recovery of carbon stocks showed an AGB variation from 14.97 t ha-1 (initial regrowth) to 321.47 t ha-1 (mature forests). In addition to AGB, Ht was also important to discriminate the typologies.

A análise de mudanças na composição de espécies e estrutura da vegetação em cronosseqüências aprimora o conhecimento sobre os padrões de regeneração após o abandono das terras na Amazônia. Nosso objetivo foi realizar análise florístico-estrutural em florestas maduras (com / sem exploração madeireira) e em sucessões secundárias (inicial, intermediária e avançada) na região do Tapajós. A idade da regeneração e os locais das parcelas foram determinados usando imagens Landsat-5 TM (1984-2012). Na análise florística, foi determinada a suficiência amostral e os índices de Shannon-Weaver (H'), uniformidade de Pielou (J), Valor de Importância (VI) e alfa de Fisher (α). Foi aplicada análise de escalonamento multidimensional não-métrico (NMDS) para ordenação de similaridade. Na análise estrutural, o diâmetro à altura do peito (DAP), altura total da árvore (Ht), área basal (BA) e biomassa acima do solo (AGB) foram obtidos. As diferenças entre tipologias dos atributos florísticos-estruturais foram verificadas utilizando os testes de Tukey e Kolmogorov-Smirnov. Os resultados mostraram aumento dos índices H', J e alfa a partir da sucessão inicial até as florestas maduras da ordem de 47%, 33% e 91%, respectivamente. O estágio avançado apresentou mais espécies em comum com o estágio intermediário do que com a floresta madura. Foram observadas diferenças estatisticamente significativas entre os estágios iniciais e intermediários (p <0,05) para o DAP, BA e Ht. O retorno dos estoques de carbono mostrou uma variação de AGB de 14,97 t ha-1 (estágio inicial) para 321,47 t ha-1(florestas maduras). Além de AGB, Ht também foi um atributo importante para discriminar as tipologias.

Logging impacts on forest structure and seedling dynamics in a Prioria copaifera (Fabaceae) dominated tropical rain forest (Talamanca, Costa Rica) / Impactos de la extracción en la estructura y la dinámica de plántulas en un bosque tropical dominado por Prioria copaifera (Fabaceae), (Talamanca, Costa Rica)

The factors that determine the existence of tropical forests dominated by a single species (monodominated forests) have been the subject of debate for a long time. It has been hypothesized that the low frequency of disturbances in monodominated forests and the tolerance to shade of the monodominant species are two important factors explaining the prolonged dominance of a single species. We determined the role of these two factors by examining the effects of logging activities on the floristic composition and seedling dynamics in a Prioria copaifera dominated forest in Southeastern Costa Rica. We determined the floristic composition for trees ≥2.5cm DBH and the associated recruitment, survival and mortality of tree canopy seedlings in two sites logged two (L-02) and 12 years (L-12) prior to sampling and an unlogged forest (ULF). Our results showed that L-02 stands had lower species richness (25 species) than the L-12 and ULF stands (49 and 46 species, respectively). As expected, we found significant logging effects on the canopy structure of the altered forests, particularly when comparing the L-02 and the ULF stands. Seedling density was higher in ULF (0.96 seedlings/m²) than in the L-02and L-12 stands (0.322 and 0.466 seedlings/m², respectively). However, seedling mortality was higher in the ULF stands (54%) than in the L-02 (26%) and L-12 (15%) stands. P. macroloba in L-02 was the only species with abundant regeneration under P. copaifera in L-02 stand, where it accounted for 35% of the seedlings. Despite the reduction in seedling abundance observed after logging, P. copaifera seems to maintain large seedling populations in these forests, suggesting that this species maintains its dominance after logging disturbances. Our findings challenge the hypothesis that the regeneration of monodominant species is not likely to occur under heavily disturbed canopy conditions. Rev. Biol. Trop. 62 (1): 347-357. Epub 2014 March 01.

La determinación de los factores responsables de la existencia de bosques tropicales dominados por una sola especie (bosques monodominados) ha sido motivo de debate por largo tiempo. Se ha propuesto que la baja frecuencia de alteraciones en esos bosques y la tolerancia a la sombra de las plántulas de la especie monodominante son dos de los factores que contribuyen a explicar la prolongada dominancia de una sola especie en estos bosques. Se estudió el rol de estos dos factores evaluando el efecto de la extracción de madera sobre la composición florística y la supervivencia y crecimiento de plántulas en un bosque dominado por Prioria copaifera en la región sureste de Costa Rica. Para ello se determinó la composición florística de los árboles con un diámetro a la altura de pecho (DAP) ≥2.5cm y el reclutamiento, supervivencia y mortalidad de las plántulas de especies arbóreas en sitios donde se extrajo madera dos (L-02) y doce años (L-12) antes de este estudio y un sitio del que nunca se ha extraído madera (ULF). Nuestros resultados muestran que los bosques L-02 tienen una riqueza de especies menor (25 especies) que los bosques L-12 y ULF (49 y 46 especies, respectivamente). Como era de esperar, la extracción de madera tuvo efectos significativos en la estructura del dosel del bosque, particularmente al comparar los bosques L-02 y ULF. La densidad de plántulas fue mayor en bosques ULF (0.96 plántulas/m²) que en L-02 y L-12 (0.322 and 0.466 plántulas/m², respectivamente). Sin embargo, la mortalidad de plántulas fue mayor en ULF (54%) que en L-02 (26%) y L-12 (15%). Pentachletra macroloba fue la única especie que mostró abundante regeneración bajo P. copaifera en parcelas L-02, representando el 35% las plántulas encontradas. A pesar de la reducción de la abundancia de plántulas observada después de la extracción de madera, P. copaifera parece capaz de mantener grandes poblaciones de plántulas en estos bosques. Estos resultados sugieren que P. copaifera puede mantener su dominancia después de las alteraciones causadas por la extracción de madera. Nuestros resultados no apoyan la hipótesis de que la regeneración de las especies monodominates es menos probable cuando el dosel del bosque sufre fuertes alteraciones.

Fitossociologia e uso múltiplo de espécies arbóreas em floresta manejada, comunidade Santo Antônio, município de Santarém, estado do Pará / Phytosociology and multiple use of forest species in a logged forest in Santo Antonio community, municipality of Santarém, Pará state

Avaliou-se a fitossociologia de floresta manejada em lotes de comunitários da Comunidade Santo Antônio no Assentamento Moju I e II, município de Santarém, Amazônia brasileira. Foram instaladas 12 parcelas de 50 m x 200 m (1 por lote) anotando-se indivíduos com CAP ≥ 157,1 cm (nível 3 de inclusão); 12 sub-parcelas de 50 m x 50 m, para os indivíduos com 94,2 cm ≤ CAP < 157,1 cm (nível 2 de inclusão) e 12 sub-parcelas de 50 m x 25 m, para os indivíduos com 31,4cm ≤ CAP < 94,2 cm (nível 1 de inclusão). Foram amostrados 1.227 indivíduos, distribuídos em 175 espécies e 38 famílias botânicas. A família Fabaceae apresentou maior número de espécies e o gênero mais rico foi Inga. O Índice de Diversidade de Shannon (H') foi 4,39 e o Índice de Equabilidade de Pielou (J) de 0,85. A avaliação do Valor de Importância Ampliado (VIA) das espécies da amostra revelou o estoque de espécies com potencial madeireiro e não madeireiro. Carapa guianensis, Caryocar villosum, Brosimum parinarioides, Aniba canellila, Bowdichia virgilioides e Andira surinamensis podem ser aproveitadas como produtos florestais não madeireiros e serem removidas da lista de espécies de corte para fins madeireiros, melhorando assim o retorno econômico comunitário. Manilkara huberi e Carapa guianensis foram espécies com utilização madeireira e não madeireira mais expressivas, considerando o mercado atual e potencial de usos conhecidos; portanto, tais características devem ser consideradas no planejamento e execução do manejo da floresta.

The forest potential was evaluated in the logged area in the Moju I and II Settlement, located at a secondary road near km 124 of the BR 163 highway, in the municipality of Santarém, Brazilian Amazonia. Twelve 50 m x 200 m plots were established in a 12 ha sample area, in which all trees CPH (circumference 1.3 m above ground) > 157.5 cm were recorded; twelve 50 m x 50 m subplots in which individuals 94.2 cm ≤ CAP < 157.1 cm were recorded; and twelve 50 m x 25 m subplots for measuring individuals 31.4 cm ≤ CAP < 94.2 cm. A total of 1227 trees from 175 species and 38 families were recorded in the forest sample. Higher number of species was found in Fabaceae and genus Inga was the richest. Diversity Shannon index (H') was 4.39 and Evenness index (J) was 0,85. The analysis of VIA showed that remain forest keeps a stock of timber and non-timber potential species for using by the community. Carapa guianensis, Caryocar villosum, Brosimum parinarioides, Aniba canellila, Bowdichia virgilioides and Andira surinamensis can be suggested to be removed from the timber harvesting list, thus improving community economic return. Manilkara huberi and Carapa guianensis were the species with more expressive timber and non-timber uses, respectively, according to the present market and the potential of known uses; so it will be very interesting that these characteristics can be taking into consideration during the elaboration of plans and management of the forest.

Description of the Panamá and Iguanita mangrove stands of Bahía Culebra, North Pacific coast of Costa Rica / Descripción de los manglares de Panamá e Iguanita de Bahía Culebra, costa del Pacífico Norte de Costa Rica

Mangrove forests are abundant and important coastal marine ecosystems that are being impacted by human activity in Costa Rica. There are two mangrove stands (Panama and Iguanita) in Bahia Culebra, Guanacaste, North Pacific coast of Costa Rica. Their forest structure was determined with the Point-Centered Quarter Method (PCQM) during the dry season (December 2007-March 2008). Eleven transects were established at Panama mangrove, with a total of 52 points and 208 quadrats. Two transects were established at Iguanita with a total of 16 points and 62 quadrats given access difficulty. Mapping of both stands was done with two georeferenced MASTER CARTA 2005 images. Images were digitized to 1:5000 scale using the following categories: mangrove forest, low density mangrove, no mangrove, transition to dry forest, sand and water. In the area studied at Panama was 13.7ha, and 40.8ha for Iguanita. Panama is mostly composed of dense mangrove forest (51% of total study area) and dry forest species (35% of total study area). A small area (2%) had dry soil and scarce mangrove trees and the remaining 12% corresponds to water, sand and other areas without vegetation. At Iguanita, 84% was dense mangrove, 5% scarce mangrove trees and the remaining 10% corresponds to water, sand and other areas without vegetation. Five mangrove species were encountered at Panama (Avicennia germinans, Avicennia bicolor, Conocarpus erectus, Laguncularia racemosa, and Rhizophora mangle), and three at Iguanita (A. germinans, L. racemosa, and R. mangle). Species zonation was similar at both stands; with Rhizophora near water channels and inundated areas, Avicennia frequent in drier areas, and Laguncularia (both stands) and Conocarpus (only Panama) more frequent near fresh water input. Densities at both stands (Iguanita= 67.2 and Panama= 8.4 stems/0.1 ha) were lower than reported for the north Pacific of Costa Rica. Complexity index was higher at Iguanita (CI= 86.5) with R. mangle dominance, than Panama (CI= 1.1) with A. germinans dominance. While both stands are in Bahia Culebra, structurally they are very different and seem to be under two different hydrodynamic contexts. Sea level rise related to global climate change might impact both mangrove stands as they would not be able to migrate further inland (given land elevation at the back of Iguanita, and a paved road at Panama). Given the socio-economic and ecological importance of mangrove habitats, further study and continued conservation efforts of Costa Rican mangroves are needed.

Los manglares son abundantes e importantes ecosistemas marino-costeros en Costa Rica pero están siendo afectados por la actividad humana. Se analizo la estructura y cobertura de ambos manglares presentes en Bahía Culebra (Panamá e Iguanita), Guanacaste, Pacifico norte de Costa Rica. Se utilizo el PCQM para estructura durante la época seca entre diciembre 2007 y marzo 2008. Se utilizaron dos imágenes MASTER CARTA 2005 georreferenciadas para mapeo. El área aproximada de bosque de manglar en Panamá fue de 13.7ha; y de 40.8ha en Iguanita. Panamá contiene 51% de manglar denso en el área de estudio, 35% bosque seco, 2% sin vegetación y 12% de arena o agua. En Iguanita el 84% del área corresponde a manglar denso, 5% manglar de baja densidad y 10% sin cobertura vegetal o era arena o agua. Se hallaron cinco especies de manglar en Panamá (Avicennia germinans, Avicennia bicolor, Conocarpus erectus, Laguncularia racemosa y Rhizophora mangle); y tres en Iguanita (A. germinans, L. racemosa y R. mangle). En general, la presencia de las especies de manglar siguió un patrón similar en ambos manglares. La densidad total fue menor que en manglares cercanos; y Panamá (8.4tallos/0.1ha) mucho menor que Iguanita (67.2tallos/0.1 ha). El Índice de Complejidad (IC) fue mucho mayor en Iguanita (IC= 86.5), con dominancia de R. mangle, que en Panamá (IC= 1.1), con dominancia marcada de A. germinans. Estructuralmente ambos manglares son muy distintos entre sí y parecen encontrarse en contextos hidrodinámicos diferentes.

Changes in structure and composition of evergreen forests on an altitudinal gradient in the Venezuelan Guayana Shield

There have been several ecological studies in forests of the Guayana Shield, but so far none had examined the changes in structure and composition of evergreen forests with altitude. This study describes and analyzes the structure, species composition and soil characteristics of forest stands at different altitudinal zones in Southeastern Venezuelan Guayana, in order to explain the patterns and the main factors that determine the structure and composition of evergreen forests along the altitudinal gradient. Inventories of 3 948 big (>10cm DBH) and 1 328 small (5-10cm DBH) woody stems were carried out in eleven plots, ranging from 0.1 to 1.0ha, along a 188km long transect with elevations between 290 and 1 395masl. It has been found that 1) hemiepihytes become more dominant and lianas reduce their dominance with increasing altitude and 2) the forest structure in the study area is size-dependent. Five families and 12 genera represented only 9% of the total number of families and genera, respectively, recorded troughout the gradient, but the two groups of taxa comprised more than 50% of the Importance Value (the sum of the relative density and the relative dominance) of all measured stems. Moreover, the results suggest that low species richness seems to be associated with the dominance of one or few species. Stand-level wood density (WD) of trees decreased significantly with increasing elevation. WD is an indicator of trees’life history strategy. Its decline suggests a change in the functional composition of the forest with increasing altitude. The Canonical Correspondence Analysis (CCA) indicated a distinction of the studied forests on the basis of their altitudinal levels and geographic location, and revealed different ecological responses by the forests, to environmental variables along the altitudinal gradient. The variation in species composition, in terms of basal area among stands, was controlled primarily by elevation and secondarily ...

A pesar de los diversos estudios ecológicos realizados en los bosques del Escudo de Guayana, ninguno de ellos había analizado hasta ahora los cambios en la composición y estructura de bosques siempreverdes que ocurren al incrementar la altitud. Con el fin de identificar patrones y factores determinantes de la estructura y la composición de bosques en un gradiente altitudinal (290-1 395msnm) en el sudeste de Venezuela se realizaron inventarios de 3 948 fustes grandes (>10cm DAP) y 1 328 pequeños (5-10cm DAP) en once parcelas a lo largo de un transecto de 188km. Con el incremento de la altitud, el área basal aumenta en las hemiepífitas y disminuye en las lianas. Las familias y los géneros más importantes representaron una reducida proporción del total de taxones, pero abarcaron más del 50% del Valor de Importancia. Bajos valores de riqueza se asocian con la dominancia de pocas especies. La densidad de madera decrece significativamente a mayor altitud, y sugiere un cambio en la composición funcional. Existen diferentes respuestas ecológicas de los rodales ante cambios físico-ambientales. La variación de la composición de especies en el gradiente fue controlada por altitud, lluvia y condiciones edáficas; pero se desconoce el efecto de otros factores no considerados como régimen de perturbaciones, interacciones biológicas, productividad e historia de dispersión. La variabilidad observada en la estructura y la composición de bosques en el gradiente parece ser un resultado del efecto combinado de diferentes climas y procesos locales aleatorios que interactúan en un complejo paisaje.

Structure of mixed ombrophyllous forests with Araucaria angustifolia (Araucariaceae) under external stress in Southern Brazil

This study is part of the Floristic and Forest inventory of Santa Catarina, conceived to evaluate forest resources, species composition and structure of forest remnants, providing information to update forest conservation and land use policy in Southern Brazilian State of Santa Catarina (95 000km²). In accordance to the Brazilian National Forest inventory (IFN-BR), the inventory applies systematic sampling, with 440 clusters containing four crosswise 1 000m² plots (20x50m) each, located on a 10x10km grid overlaid to land use map based on classification of SPOT-4 images from 2005. Within the sample units, all woody individuals of the main stratum (DBH≥10cm) are measured and collected (fertile and sterile), if not undoubtedly identified in field. Regeneration stratum (height>1.50m; DBH<10cm) is registered in 100m² in each sample unit. Floristic sampling includes collection of all fertile trees, shrubs and herbs within the sample unit and in its surroundings. This study performs analysis based on 92 clusters measured in 2008 within an area of 32 320km² of mixed ombrophyllous forests with Araucaria angustifolia located at the state’s high plateau (500m to 1 560m above sea level at 26º00’-28º30’ S and 49º13’-51º23’ W). Mean density (DBH≥10cm) is 578 individuals/ha (ranging from 85/ha to 1 310/ha), mean species richness in measured remnants is 35 (8 to 62), Shannon and Wiener diversity index (H’) varies between 1.05 and 3.48. Despite high total species diversity (364 Magnoliophyta, five Coniferophyta and one tree fern) and relatively high mean basal area (25.75m²/ha, varying from 3.87 to 68.85m²/ ha), the overwhelming majority of forest fragments are considered highly impacted and impoverished, mostly by logging, burning and extensive cattle farming, turning necessary more efficient protection measures. Basal area was considered an appropriate indicator for stand quality and conservation status. Rev. Biol. Trop. 59 (3): 1371-1387. Epub 2011 September 01.

Este estudio es parte del inventario Florístico Forestal de Santa Catarina, realizado para evaluar los recursos forestales, la composición de especies y la estructura de remanentes de bosque, y proporciona información para actualizar la conservación de los bosques y políticas de uso de la tierra en el estado brasileño de Santa Catarina (95 000km²). El inventario se aplica al muestreo sistemático, de 440 conglomerados en cuatro parcelas de 1 000m² cada una, situados en una red de 10x10km. Dentro de las parcelas, todos los individuos leñosos (DAP≥10cm) fueron medidos. El estrato de regeneración (altura>1.50m, DAP<10cm) se registra en 100m² en cada conglomerado. Este estudio realiza un análisis de 92 conglomerados medidos en 2008 dentro de un área de 32 320km² de bosques ombrófilos mixtos con Araucaria angustifolia ubicados en el altiplano del estado. La densidad media (DAP≥10cm) es de 578 individuos/ha (desde 85/ha hasta 1 310/ha), la media de la riqueza de especies en los remanentes es de 35 (8-62), la diversidad (H’) de Shannon y Wiener varía entre 1.05 y 3.48. A pesar de la alta diversidad total de especies (364 Magnoliophyta, cinco Coniferophyta y un helecho arborescente) y el alto promedio del área basal (25.75m²/ha, variando de 3.87 a 68.85m²/ha), la mayoría de los fragmentos de bosque se consideran altamente impactados por la tala, quema y ganadería extensiva, por lo tanto es necesario más medidas eficaces de protección.

Abundância e diversidade de palmeiras no Distrito Florestal Sustentável da rodovia BR-163, Pará, Brasil / Abundance and diversity of palms in the Sustainable Forest District of BR-163 road, Pará, Brazil

A abundância e a diversidade de espécies, bem como a relação com a estrutura da floresta foram investigadas no Distrito Florestal Sustentável (DFS) da rodovia BR-163. Foram estabelecidas 40 parcelas de 0,04 ha (20 × 20 m) em uma mata prístina no Parque Nacional (PARNA) da Amazônia e 40 parcelas semelhantes em uma área submetida à exploração madeireira na Floresta Nacional do Tapajós. Em cada parcela, as árvores com DAP ≥ 10 cm foram medidas e as palmeiras adultas identificadas e contadas. Foi verificado que, apesar da floresta explorada da FLONA do Tapajós ser estruturalmente mais aberta que a mata do PARNA, apresenta menor quantidade e menor diversidade de espécies, provavelmente devido às limitações da dispersão de frutos e sementes e pela recente exploração madeireira. Conclui-se que, o potencial de exploração das palmeiras em matas nativas de terra firme da região é limitado pela escassez natural das espécies de maior potencial econômico, contudo, poderia ser ampliado com o plantio de espécies economicamente úteis.

The abundance and diversity of palm species, as well as its relationship with forest structure were investigated in two study areas in the Sustainable Forest District of the BR-163 road. As such, forty parcels of 0.04 ha (20 × 20 m) were established in a pristine forest in the Amazonia National Park, and another forty parcels in a area submitted to timber logging in the Tapajos National Forest. In each parcel, all the trees with DBH ≥ 10 cm were measured and the adult palms were identified and counted. We verified that although the exploited forest of the Tapajos National Forest is structurally more open than the forest in the national park, it still has a quantity and diversity of palms inferior to the national park, probably due to the dispersal limitation of palms and the relatively recent logging activities. We concluded that exploitation potential of palms in native forests of the region is extremely limited by the natural scarcity of palms in native forests of economic potential, but could be amplified with the deliberate planting of useful species, with benefits for the natural dynamics of the forest.

Composição e similaridade florística entre duas áreas de Floresta Atlântica Montana, São Paulo, Brasil / Floristic composition and similaritie between areas of Montane Atlantic Rainforest, São Paulo, Brazil

O trabalho foi desenvolvido em duas parcelas de 1 ha de Floresta Ombrófila Densa Montana do Núcleo Santa Virgínia, Parque Estadual da Serra do Mar, São Luiz do Paraitinga/SP, Brasil. Além de determinar a estrutura e a composição florística do componente arbóreo de cada parcela, o trabalho teve como objetivo comparar uma área (PLOT N) onde, segundo relatos de antigos moradores da região, houve corte seletivo de madeira até meados da década de 70 do século passado, com outra área (PLOT K) sem histórico de perturbação antrópica recente. As duas parcelas, que distam entre si cerca de 4 km, foram subdivididas em 100 subparcelas de 10 × 10 m e todos os indivíduos com DAP > 4,8 cm foram marcados, mapeados, medidos e identificados. Ao todo foram amostrados 3.503 indivíduos, sendo 2.269 árvores (64,7 por cento), 860 palmeiras (24,5 por cento) e 159 (4,5 por cento) fetos arborescentes, distribuídos em 265 espécies e 51 famílias. O restante dos indivíduos (215) estava morto. Dentre as famílias mais abundantes (Arecaceae, Myrtaceae, Lauraceae, Cyatheaceae), Monimiaceae é a única considerada típica da fitofisionomia Montana da Floresta Ombrófila Densa Atlântica. Euterpe edulis Mart. (Arecaceae) é a espécie dominante no PLOT K (pristina), onde foram registrados 1.852 indivíduos, distribuídos em 189 espécies e 43 famílias, sendo Myrtaceae (48), Lauraceae (26) e Monimiaceae (13) as que apresentaram a maior diversidade de espécies. É importante mencionar que moitas de bambu nativo (Merostachys neesii Ruprecht, Poaceae) estão presentes em 93 das 100 subparcelas desse plot, totalizando 3.813 colmos. Em contraste, no PLOT N, em que Euterpe edulis também é a espécie dominante, mas os bambus não estão tão presentes, foram identificados 1.436 indivíduos, distribuídos em 149 espécies e 40 famílias, com destaque para Myrtaceae (27), Lauraceae (15) e Fabaceae (oito) em termos de número de espécies. Na área de floresta secundária (PLOT N) o índice de diversidade de Shannon (H' = 4,05 ) e o índice de equidade (J ' = 0,8) são mais altos do que os valores encontrados na área que não sofreu corte seletivo (PLOT K) onde H' = 3,72 nats.ind-1 e J' = 0,7. No entanto, a estimativa do número máximo de espécies esperado no ponto de rarefação do PLOT N (IC por cento 95-158,54) se sobrepõe parcialmente à estimativa do número mínimo de espécies do PLOT K (95 por cento - 157,12), mostrando que o número de espécies de ambas as áreas se equivaleriam em 1420 indivíduos. Embora a maior árvore amostrada tenha sido encontrada no PLOT K, no qual os estratos da floresta são mais evidentes, não há diferença significativa entre as somas de área basal de indivíduos vivos das duas parcelas. Considerando o histórico de perturbação da região, os resultados sugerem que a recuperação da estrutura da floresta pode ocorrer dentro de 25 anos, mas, como mostrado pelo número total de espécies e pelo índice H' do PLOT K, este período é insuficiente para recuperação da diversidade de espécies arbóreas características da Floresta Ombrófila Densa Atlântica antiga.

The study was conducted in two areas of Montana Atlantic Rainforest at Núcleo Santa Virgínia, Serra do Mar State Park, Brazil. The aim was to investigate structural and floristic composition of each area and the differences between them, knowing that one has not been disturbed recently and the other was subjected to selective logging until 1970, as reported by local people. We installed two 1 ha (PLOT K and PLOT N), approximately 4 km away from each other, and within this plots all individuals with DBH > 4.8 cm were recorded. Considering the two plots we sampled 3,503 individuals (2,269 trees - 64.7 percent; 860 palms - 24.5 percent; and 159 ferns - 4.5 percent), distributed in 265 species and 51 families. The rest (215 individuals) was dead. Among the most abundant families (Arecaceae, Myrtaceae, Lauraceae, Cyatheaceae) Monimiaceae is the only one classified as typical of the Montane Ombrophylus Dense Atlantic Forest. Euterpe edulis Mart. (Arecaceae) is the dominant species in PLOT K (old), where we recorded 1,852 individuals, 189 species and 43 families, with Myrtaceae (48), Lauraceae (26) and Monimiaceae (13) presenting the higher number of species. It is important to mention that clumps of a native bamboo (Merostachys neesii Ruprecht, Poaceae) are present in 93 of the 100 subparcels of PLOT K, summing up 3,813 culms. In contrast, in PLOT N (secondary) where palm heart (Euterpe edulis) is also the dominant species but bamboos are not so conspicuous, we recorded 1436 individuals, 149 species and 40 families, with Myrtaceae (27), Lauraceae (15) and Fabaceae (eight) being the ones with higher number of species. In the plot of secondary forest (N) Shannon's diversity index (H' = 4.05 ) and the eveness index (J ' = 0.8) are higher than those recorded in the old plot of forest (K) where H' = 3,72 nats.ind-1 and J' = 0.7. Plots K and N have a low similarity (Jaccard index C J = 0,3), with only 94 species (34,47 percent) in common, and 102 (38,5 percent) occurring exclusively in PLOT K. However, the maximum estimate of species expected at the point of rarefaction of PLOT N (IC 95 percent - 158.54) overlaps with the minimum estimate of species at the same point of PLOT K (95 percent - 157.12), showing that the number of species of both areas would be equivalent in the number of 1,420 individuals. Although the largest tree sampled was found in PLOT K, where forest stratification is more evident, there is no significant difference between the sums of basal area of living individuals. Considering the disturbance history of the region, the results suggest that forest structure recovery may occur within 25 years but, as shown by the total number of species and by the diversity parameters determined, species richness does not recover within this time frame.

Efeito de duas intensidades de colheita de madeira na estrutura de uma floresta natural na região de Paragominas, Pará

Changes in the forest structure were analyzed considering two harvest intensities in 108ha of primary forest in the Rio Capim Forest Management Unit, belonging to Cikel Brasil Verde Madeiras Ltda., in the municipality of Paragominas, Pará. Data were collected in 2003 (before harvesting) and 2004 (after harvesting) in 36 0.25ha permanent sample plots, randomly distributed in the area (12 in unlogged forest, 12 in logged forest and 12 in logged forest plus extraction of coarse woody debris). Before logging (2003), 4469 trees with DBH > 10cm were recorded in the 36 plots (9ha sample). Seven months after logging (2004), the number of trees increased to 4531 but only 4330 were found alive. Lecythis idatimon, Poecilanthe effusa, Rinorea flavescens, Eschweilera grandiflora, Eschweilera pedicellata, Inga sp., Protium spp., Vouacapoua americana, Guatteria poeppigiana and Eschweilera coriacea were the ten most important species both before and after logging. Forest structure, in the two harvest intensities, had significant changes due to the logging. But there were no significant changes between the two logged areas, suggesting that the extraction of the coarse woody debris after logging did not cause significant damage to the remaining forest. Forest structure changed slightly after logging but these changes were not significant among the three communities. Despite the reduction in adult tree stock of commercial species due to logging and coarse woody debris extraction, the stand kept characteristics similar to the original forest. Studies on natural regeneration (DBH 10cm), pos-harvesting silviculture and growth of the forest are recommended.

Foram estudadas as mudanças na estrutura de 108ha de uma floresta primária submetida a duas intensidades de colheita de madeira, na Fazenda Rio Capim, pertencente à Cikel Brasil Verde Madeiras Ltda., no município de Paragominas, Pará. Os dados foram coletados, em dois períodos (2003, antes da exploração, e 2004, após a exploração) em 36 parcelas permanentes quadradas de 0,25ha, estabelecidas aleatoriamente na área, sendo12 em floresta não-explorada: Testemunha - T0; 12 em floresta explorada com colheita apenas do fuste comercial das árvores: Tratamento - T1; e 12 em floresta explorada com colheita do fuste e dos resíduos lenhosos: Tratamento - T2. Em 2003 foram registrados 4469 indivíduos com DAP > 10cm, nas 36 parcelas amostradas (9ha). Sete meses após a exploração (2004), foram observados na área 4531 indivíduos com DAP > 10cm, sendo 4330 vivos. Lecythis idatimon, Poecilanthe effusa, Rinorea flavescens, Eschweilera grandiflora, Eschweilera pedicellata, Inga sp., Protium spp., Vouacapoua americana, Guatteria poeppigiana e Eschweilera coriacea foram as dez espécies mais importantes, tanto antes como após a exploração. A estrutura da floresta, tanto no T1 como no T2, sofreu alterações significantes devido à exploração a que foi submetida. Entretanto, não foram verificadas diferenças significativas entre os três tratamentos, sugerindo que com a intensidade de exploração aplicada, mais a retirada adicional dos resíduos, a floresta manteve as características semelhantes à floresta original, apesar do menor estoque de árvores adultas de espécies comerciais. Recomendam-se estudos sobre a regeneração natural (DAP 10cm), silvicultura pós-colheita e crescimento da floresta.