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Neighboring upland and nutrient-poor seasonally flooded Amazon forests were penetrated by a fire in 2009, providing a natural com-parative experiment of fire damage for these widespread forest types. In upland, only 16 10% ( 2 SEM) of stems and 21 8%of basal area were lost to fire, while seasonally flooded forest lost 59 13% of stems and 57 13% of basal area. Drier understorycontributes to greater flammability. Much of the area occupied by seasonally flooded woody vegetation (>11.5 percent of the Amazonregion) is vulnerable to fire due to high flammability and slow recovery.Abstract in Portuguese is available in the online version of this article. Key words: flammability; forest structure; igapo; litter layer; relative humidity; tropical forest. O VER 11.5 PERCENT OF THE AMAZON BASIN IS OCCUPIED BY SEASON-ALLY INUNDATED WOODY VEGETATION (Melack & Hess 2010).Seasonally flooded Amazon forests are home to a high diversityof trees (Wittmann et al. 2010), endemic invertebrates (Adis et al.2010) and frugivorous fish (Goulding et al. 1988, Correa et al.2007). Although inundated for much of the year, the litter layerof a low open-canopy floodplain forest of the upper Rio Negrocan ignite when relative humidity of the understory drops below65 percent (Uhl et al. 1988).Fire also penetrates closed-canopy floodplain forests of themiddle Rio Negro. Using field inventories and high-resolutionimages Flores et al. (2014) found average tree mortality of 90 per-cent from fires associated with droughts—much higher than themortality or percent of biomass loss reported after a first burn ofupland forests (Barbosa & Fearnside 1999, Cochrane et al. 1999,Barlow & Peres 2004). Amazon forests seasonally flooded bynutrient-poor waters have an aerated root mat and accumulationof leaf litter which together comprise a stock of fine, quick-dryingfuel two to three times larger than in nearby upland forest(Kauffmann et al. 1988, Dos Santos & Nelson 2013).These prior results suggest that flooded forest is less resistantto fire damage than upland forest. However, no experiment has yetbeen performed comparing fire resistance of these two widespreadforest types. The Rio Negro provides few situations to compareflammability; river channels act as fire breaks between the two for-est types and ignition sources differ (e.g., fishermen’s campfires aremore abundant in the floodplain). A report by Nelson (2001) com-pared fire damage between upland and floodplain forests in closeproximity and penetrated by the same fire, but relied only on visualinspection of satellite images and air photography.Here, we use a natural experiment to address the hypothesisthat given equal ignition opportunity and identical recent rainfallhistory, fire will cause greater damage to undisturbed nutrient-poor flooded forest than undisturbed upland forest (H1). Oursecond hypothesis examines cause: The unburned flooded forestunderstory has more prolonged periods of flammability than theunburned upland forest understory (H2).South of the central sector of the Amazon River are exten-sive terraces 15–20 m above the present local high water level.Irion et al. (2010) interpret these as paleo-floodplains depositedduring Pleistocene interglacial periods, such as 110,000 years ago,when the Amazon River was slightly above its present relativelevel. During the final Pleistocene low sea stand the paleo-flood-plains became upland and were weakly incised by erosion, form-ing dense dendritic networks of shallow valleys. Post-Pleistocenesea level rise back-flooded the Amazon main stem and theseshallow incised valleys. Currently, they are seasonally inundatedby a 10 m amplitude annual flood pulse and are colonized bytrees tolerant to periodic inundation. Between the seasonallyflooded valleys, the paleo-floodplain terrace forms flat narrowinterfluves covered by flood intolerant upland tree species.For three reasons, fires on this landscape provide the idealnatural experiment to address H1. First, tree cover is continuousbetween the two forest types, with no intervening open water orerosional scarp to impede passage of fire. Second, the two foresttypes are spatially intercalated because of the dense network ofseasonally flooded valleys, allowing placement of all plots in closeproximity. As a result, sites can have identical pre-burn rainfalland equal ignition opportunity when fires course through the sea-sonally flooded valley forest (Fig. S1). Finally, because ignitionsources for both forest types (swidden fields and pastures) wereabsent over much of the area until recent decades, it is easy tofind forest that has burned only once.

Xishuangbanna is a region located at the northern edge of tropical Asia. Biomass estimates of its tropical rain forest have not been published in English literature. We estimated forest biomass and its allocation patterns in five 0.185‐1.0 ha plots in tropical seasonal rain forests of Xishuangbanna. Forest biomass ranged from 362.1 to 692.6 Mg/ha. Biomass of trees with diameter at 1.3 m breast height (DBH) ≥ 5 cm accounted for 98.2 percent of the rain forest biomass, followed by shrubs (0.9%), woody lianas (0.8%), and herbs (0.2%). Biomass allocation to different tree components was 68.4‐70.0 percent to stems, 19.8‐21.8 percent to roots, 7.4‐10.6 percent to branches, and 0.7‐1.3 percent to leaves. Biomass allocation to the tree sublayers was 55.3‐62.2 percent to the A layer (upper layer), 30.6‐37.1 percent to the B layer (middle), and 2.7‐7.6 percent to the C layer (lower). Biomass of Pometia tomentosa, a dominant species, accounted for 19.7‐21.1 percent of the total tree biomass. The average density of large trees (DBH ≥100 cm) was 9.4 stems/ha on two small plots and 3.5 stems/ha on two large plots, illustrating the potential to overestimate biomass on a landscape scale if only small plots are sampled. Biomass estimations are similar to typical tropical rain forests in Southeast Asia and the Neotropics.

Tropical dry forests are located predominantly in the northern portion of Venezuela, above 6°N. Although their potential extent covers ca 400,000 km2 (44% of the land), they currently occupy about 10 percent of this area. The diversity and complexity of Venezuelan dry forests increases from north to south along a gradient of decreasing severity of the dry season. A typical dry forest in Venezuela presents ca 110–170 species of plants from ca 40 to 50 families within an area of approximately 10 ha. Species composition and forest structure, however, are dependent on local landscape conditions (e.g., soil type, topography), and nearby forest types can be very different. Our analysis of five dry forest variants showed a maximum family similarity of 67 percent, although most values fell in the 50–60 percent interval. They are currently considered as one of Venezuela's most threatened ecosystems, but only 5 percent of extant dry forests are included in protected areas; this represents 0.5 percent of their potential extent. It is fundamental to promote the creation of at least 3 or 4 more large protected areas (ca 5000 ha), with different climatic and orographic characteristics, in combination with the recovery of threatened species, the restoration of degraded systems, and the implementation of sustainable development projects. Their apparent high resilience suggests that with the proper management we can restore and maintain the integrity of Venezuelan dry forests. RESUMEN Los bosques secos tropicales de Venezuela se ubican predominantemente al norte del pais, por encima de los 6°N. Aunque su distribucion potencial abarca ca 400,000 km2 (44 porciento del territorio terrestre), actualmente ocupan 10 porciento de esta area. La diversidad y complejidad de bosques secos en Venezuela aumenta de norte al sur, la direccion en la que el numero de meses secos disminuye de 8 a 3. Un bosque seco tipico en Venezuela presenta ca 110–170 especies de plantas, de ca 40–50 familias. La composicion de especies y la estructura de los bosques, sin embargo, son dependientes de las condiciones locales del terreno (e.g., tipo de suelo, topografia), por lo que tipos de bosque cercanos pueden ser muy diferentes. Nuestro analisis de cinco variantes revelo una similaridad entre familias de 67 porciento, aunque la mayoria de los valores cayo entre 50 y 60 porciento. Actualmente son considerados como uno de los ecosistemas venezolanos mas amenazadas, pero solo 5 porciento de los bosques secos remanentes estan incluidos en areas protegidas; esto representa 0.5 porciento de su distribucion potencial. Es fundamental promover la creacion de al menos 3 o 4 areas protegidas grandes adicionales (ca 5000 ha), con condiciones climaticas y orograficas diferentes, en combinacion con la recuperacion de especies amenazadas, la restauracion de sistemas degradados y la implementacion de proyectos de desarrollo sostenible. Su alta resiliencia aparente sugiere que con el manejo adecuado se podria restaurar y mantener la integridad de los bosques secos de Venezuela.

We integrate forest structure and remotely sensed data for four successional stages (pasture, early, intermediate, and late) of a tropical dry forest area located in the Sector Santa Rosa of the Guanacaste Conservation Area in northwestern Costa Rica. We used a combination of spectral vegetation indices derived from Landsat 7 ETM+ medium resolution and IKONOS high-resolution imagery. The indices (using the red and near-infrared bands) simple ratio and normalized difference vegetation index separated the successional stages well. Two other indices using mid-infrared bands did not separate successional stages as well. In a comparison of the successional stages with chronological age, there was no separability in the spectral reflectance among different age classes. Successional stages, in contrast, showed distinct groups with minimal overlap. We also applied a simple validation in another dry forest located in the Palo Verde National Park in the province of Guanacaste, Costa Rica, with reasonably good results. RESUMEN En este estudio, datos de campo y datos remotamente sensados son analizados para cuatro etapas sucesionales (pastos, temprano, intermedio y tardio) de un bosque seco tropical ubicado en el sector Santa Rosa del Area de Conservacion Guanacaste en el noroeste de Costa Rica. Utilizamos una combinacion de indices spectrales derivados imagenes satelitales, de mediana resolucion de Landsat 7 ETM+ y de alta resolucion de IKONOS. Los indices (usando las bandas de rojo e infrarojo cercano) de relacion simple (SR) e indice normalizado de diferencia vegetal (NDVI) separo bien las etapas sucesionales. Asi otros dos indices, usando las bandas de infrarojo medio no separaron las etapas sucesionales. En una comparacion de las etapas sucesionales con la edad cronologica, no existio separabilidad en la reflectancia espectral entre las diferentes clases de edad. Sin embargo, las etapas sucesionales mostraron grupos distinguibles con minima sobreposicion.Tambien aplicamos una simple validacion en otro bosque seco ubicado en el Parque Nacional Palo Verde en la provincia de Guanacaste, Costa Rica.

In 1998, we measured the effects of Hurricane Georges after it passed over long-term research sites in Puerto Rican dry forest. Our primary objectives were to quantify hurricane effects on forest structure, to compare effects in a large tract of forest versus a series of nearby forest fragments, to evaluate short-term response to hurricane disturbance in terms of mortality and sprouting, and to assess the ability of hurricanes to maintain forest structure. We sampled damage from 33 plots (1.3 ha) across a 3000-ha tract of forest as well as in 19 fragments. For stems with 2.5-cm minimum diameter, 1004 stems/ha (12.4%) suffered structural damage, while 69 percent of the undamaged stems were at least 50 percent defoliated. Basal area lost to structural damage equaled 4.0 m2/ha (22%) in south-facing native forests. Structural damage and defoliation increased with stem diameter and were more common in certain dry forest species. South-facing forests and those on ridgetops incurred more damage than north-facing forests or those comprised primarily of introduced species. Stem mortality was only 2 percent of all stems after 9 mo. Structural damage did not necessarily result in stem mortality. Hurricane-induced mortality was not associated with stem height or diameter, but was ten times greater than background mortality. Basal sprouting was proportional to the amount of structural damage incurred in a stand. Forest fragments experienced the same patterns of hurricane effects as the reference forest. The low, dense structure of Caribbean dry forest can be maintained by hurricane damage to larger stems and induction of basal sprouting to generate multistemmed trees. RESUMEN En 1998 medimos los efectos del Huracan George despues de que paso por sitios localizados en Puerto Rico y dedicados a la investigacion a largo plazo. Nuestros objetivos fueron cuantificar los efectos de huracanes en la estructura del bosque y comparar estos efectos en un bosque especifico con una serie de fragmentos de bosque que se encontraban en la proximidad a nuestra area de estudio. La evaluacion de la respuesta rapida del bosque seco debido a los efectos de huracanes se exploro en terminos de la mortalidad y regeneracion, asi como se estudio la habilidad de los huracanes de mantener la estructura del bosque. Para este estudio de muestreo, 33 parcelas con danos (1.3 ha) a lo largo de una seccion de 3000 ha de bosque asi como en 19 fragmentos de bosque. En tallos con ≥2.5 cm de diametro, 1004 tallos/ha (12.4%) sufrieron dano estructural, mientras que el 69 porciento de los tallos no danados fueron al menos en un 50 por ciento defoliadas. Perdidas en area basal debido al dano estructural fue equivalente a 4.0 m2/ha (22%). Bosques con pendientes en direccion sur y aquellos en los topes de las colinas presentaron mas danos que bosques con pendientes orientadas hacia el norte o aquellos que estaban constituidos principalmente de especies introducidas. Mortalidad en los tallos fue solamente un 2 porciento despues de 9 meses, asi como tambien se encontro que el dano estructural no contribuyo a la mortalidad de tallos. Mortalidad inducida por el huracan no se encontro asociada con el diametro o altura de los tallos o bien su diametro, pero fue 10 veces mas grande que la mortalidad de control. Los fragmentos de bosques experimentaron el mismo comportamiento que el bosque de referencia.

We compared plant area index (PAI) and canopy openness for different successional stages in three tropical dry forest sites: Chamela, Mexico; Santa Rosa, Costa Rica; and Palo Verde, Costa Rica, in the wet and dry seasons. We also compared leaf area index (LAI) for the Costa Rican sites during the wet and dry seasons. In addition, we examined differences in canopy structure to ascertain the most influential factors on PAI/LAI. Subsequently, we explored relationships between spectral vegetation indices derived from Landsat 7 ETM+ satellite imagery and PAI/LAI to create maps of PAI/LAI for the wet season for the three sites. Specific forest structure characteristics with the greatest influence on PAI/LAI varied among the sites and were linked to climatic differences. The differences in PAI/LAI and canopy openness among the sites were explained by both the past land-use history and forest management practices. For all sites, the best-fit regression model between the spectral vegetation indices and PAI/LAI was a Lorentzian Cumulative Function. Overall, this study aimed to further research linkages between PAI/LAI and remotely sensed data while exploring unique challenges posed by this ecosystem. RESUMEN En este estudio comparamos el indice de area de plantas PAI, el indice de area foliar (LAI), y la apertura de dosel para diferentes etapas sucesionales en tres sitios del bosque seco tropical: Chamela, Mexico; Santa Rosa, Costa Rica y Palo Verde, Costa Rica en la estacion lluviosa y seca. Ademas, examinamos las diferencias en la estructura de dosel para indagar los factores que mas influyen en el PAI/LAI. En forma adicional, exploramos las relaciones entre los indices espectrales de vegetacion derivados de imagenes satelitales Landsat 7 ETM+ y el PAI/LAI para asi crear mapas de PAI/LAI de la estacion lluviosa para los tres sitios. En este estudio encontramos que las caracteristicas especificas de la estructura del bosque con mayor influencia en PAI/LAI varian entre sitios y las mismas estan asociadas a diferencias climaticas. Las diferencias en el PAI/LAI y la apertura del dosel entre los sitios son explicadas tanto por el historial de uso del suelo y asi como las practicas de manejo del bosque. Para todos los sitios el mejor modelo de regresion entre los indices espectrales de vegetacion y el PAI/LAI es la funcion Cumulativa Lorentziana. En general, este estudio tiene como objetivo estudiar mas a fondo las relaciones entre el PAI/LAI y los datos colectados de manera remota, mientras se exploran otros retos particulares que plantea este ecosistema.

We developed and evaluated a model of the canopy of a tropical montane forest at Monteverde, Costa Rica, to estimate inorganic nitrogen (N) retention by epiphytes from atmospheric deposition. We first estimated net retention of inorganic N by samples of epiphytic bryophytes, epiphyte assemblages, vascular epiphyte foliage, and host tree foliage that we exposed to cloud water and precipitation solutions. Results were then scaled up to the ecosystem level using a multilayered model of the canopy derived from measurements of forest structure and epiphyte mass. The model was driven with hourly meteorological and event-based atmospheric deposition data, and model predictions were evaluated against measurements of throughfall collected at the site. Model predictions were similar to field measurements for both event-based and annual hydrologic and inorganicNfluxes in throughfall. Simulation of individual events indicated that epiphytic bryophytes and epiphyte assemblages retained 33-67 percent of the inorganic N deposited in cloud water and precipitation.

Dung beetles are important components of most terrestrial ecosystems. In tropical rain forests, dung beetle communities can be very rich in number of species and individuals, and they are known to be useful bioindicators of habitat disturbance. In contrast, very little is known about the organization of dung beetle communities in tropical dry forests. The aim of this study was to describe in detail the dung beetle community of a Mexican tropical dry forest and to assess the relative importance of rainfall seasonality and forest structure in affecting the temporal and spatial dynamics of this community. Dung beetles were captured with pitfall traps at the beginning of the rainy season, the middle of the rainy season, and the middle of the dry season, in two distinct forest types: deciduous forest (DF) and semideciduous forest (SDF) at the Estacion de Biologia Chamela. Both rainfall seasonality and forest structure affected the community organization of dung beetles. During both rainy periods, 14 species were captured, but only three during the dry season. Dung beetles captured during the dry season were only found in the SDF. When comparing the beginning and the middle of the rainy season, differences in abundance and guild structure were also observed between both periods and between forest types, but these differences were much less pronounced. RESUMEN Los escarabajos coprofagos constituyen un componente importante en la mayoria de los ecosistemas terrestres. En bosques humedos tropicales las comunidades de escarabajos coprofagos pueden tener muchas especies e individuos, y sirven como bioindicadores de perturbaciones de habitat. Por otro lado, se sabe muy poco acerca de las comunidades de estos insectos en bosque tropicales secos. El proposito de este estudio fue describir en detalle la comunidad de escarabajos coprofagos en un bosque seco de Mexico, y determinar la importancia relativa de la estacionalidad pluvial y la estructura del bosque en la dinamica de esta comunidad. Se capturaron escarabajos coprofagos colocando trampas de caida al principio de la epoca lluviosa, a mediados de la epoca lluviosa, y a mediados de la epoca seca, en dos tipos de bosque: bosque deciduo (BD) y bosque semideciduo (BSD) en la Estacion de Biologia Chamela. Tanto la estacionalidad como la estructura del bosque afectaron la organizacion de la comunidad de escarabajos coprofagos. En ambos periodos lluviosos se capturaron 14 especies, pero solamente tres durante la epoca seca. Los escarabajos de la epoca seca solo se encontraron en el BSD. Al comparar ambos periodos lluviosos, tambien se observaron diferencias en abundancia y estructura de gremios, entre el comienzo y la mitad de la epoca lluviosa, asi como entre los dos tipos de bosque, pero las diferencias fueron menos pronunciadas.

The ability to resist hurricane damage is a property of both individuals and communities, and can have strong effects on the structure and function of many tropical forests. We examined the relative importance of tree size, species, biogeographic origin, local topography, and damage from previous storms in long-term permanent plots in a rehabilitated subtropical moist forest in Puerto Rico following Hurricane Georges in order to better predict patterns of resistance. Severe damage included uprooted trees, snapped stems, or crowns with greater than 50 percent branch loss. Hurricane induced mortality after 21 mo was 5.2 percent/yr, more than seven times higher than background mortality levels during the nonhurricane periods. Species differed greatly in their mortality and damage patterns, but there was no relationship between damage and wood density or biogeographic origin. Rather, damage for a given species was correlated with mean annual increment, with faster growing species experiencing greater damage, suggesting that growth rate may reflect a variety of life history tradeoffs. Size was also predictive of damage, with larger trees suffering more damage. Trees on ridges and in valleys received greater damage than trees on slopes. A strong relationship was noted between previous hurricane damage and present structural damage, which could not solely be explained by the patterns with size and species. We suggest that resistance of trees to hurricane damage is therefore not only correlated with individual and species characteristics but also with past disturbance history, which suggests that in interpreting the effects of hurricanes on forest structure, individual storms cannot be treated as discrete, independent events.

Hurricanes frequently affect the forests of South and Central America; however, few studies have quantified their effects to forest structure, especially when concentrating on the food supply of an animal population. Hurricane Iris made landfall in Southern Belize on 8 October 2001, severely damaging a 52 hectare site where the behavioral ecology of a population of Central American Black Howlers (Alouatta pigra) had been under study for 2.5 yr. The hurricane resulted in a mortality rate of 35 percent for major food trees, which was primarily attributed to uprooting, snapping, and major delimbing. This damage accounted for 97 percent of the food tree loss between the two sample periods. Tree species differences were found in both the percentage loss and category of damage to food trees. Trees of different heights also experienced different percentage loss and levels of damage; subcanopy and emergent trees experienced higher loss than canopy trees, and subcanopy trees were frequently uprooted. This was partially attributed to a lack of buttressing on these subcanopy trees. Buttressing was found to decrease the frequency of uprooting. Tree size was the only factor that did not influence either damage or death. Trees from which fruit were eaten by black howlers died more than twice as often as did trees eaten for leaves.

The effects of fire on forest structure and composition were studied in a severely fire-impacted landscape in the eastern Amazon. Extensive sampling of area forests was used to compare structure and compositional differences between burned and unburned forest stands. Burned forests were extremely heterogeneous, with substantial variation in forest structure and fire damage recorded over distances of 70 percent of the sapling and vine populations. Pioneer abundance increased dramatically with burn intensity, with pioneers dominating the understory in severely damaged areas. Species richness was inversely related to burn severity, but no clear pattern of species selection was observed. Fire appears to be a cyclical event in the study region

A comparison between forest structure and use of forest by Brachyteles at Fazenda Montes Claros and Fazenda Esmeralda in Minas Gerais, Brazil indicated differences in the proportion of large trees available at the two sites. However, despite these differences in forest structure, Brachyteles at both sites showed similar preferences for feeding in trees greater than 25 cm in DBH. The results of this study suggest that forest structure, as well as forest species composition, must be evaluated before initiating efforts to translocate threatened populations of this endangered primate. RESUMO Uma compara,ao entre estrutura e uso da mata por Brachyteles na Fazenda Montes Claros e na Fazenda Esmeralda, Minas Gerais, Brasil, revelou diferen,a na propor,ao da disponibilidade de arvores de grande porte nas duas areas. No entanto, Brachyteles demonstrou preferencia alimentar por arvores maiores que 25 cm de DAP em ambas as areas. Os resultados deste estudo sugerem que a estrutura da mata, assim como sua composi,ao devem ser avaliadas antes que programas de transloca,ao de popula,ces sejam implantados.

This paper describes the impact of fire in logged-over and primary tropical forests in Sabah in terms of mortality and resultant canopy loss among saplings and trees. Prospects for recovery of forest structure and species composition are analyzed with reference to successional patterns commonly observed after natural or man-made gap forming processes

Two Amazonian terra firme forests present contrasting structures and palm compositions : one is characterized by tall and broadtrunked trees up to 50 m in height and 2.5 m in DBH, and by tall arborescent palms ; the other by more modest-sized trees up to 40 m in height and 1.3 m in DBH, and by abundant acaulescent and smaller arborescent palms. This comparison strongly suggests that forest structure and dynamics influence life forms, palms size, and species diversity. Gap size, which mainly depends on the size of upper-canopy trees, determines the intensity of light reaching the understory and thus influences the development of arborescent palms. In this analysis, acaulescent forms are regarded as an adaptation to forests with small trees and resultant small gaps. (Résumé d'auteur)