Biotropica最新文献

Patterns of gall-inducing insect diversity tend to be influenced by both habitat-related and plant-related characteristics. We investigated the distribution patterns of galling insects in four vegetation types (terra firme forest, white-sand dry forest, white-sand wet forest and palm swamp forest) of the Peruvian Amazon to test if the insect gall diversity (1) differs among different types of vegetation and (2) depends on host plant richness. In total, we found 11,579 galls belonging to 249 insect gall morphotypes, distributed across 30 botanical families and 75 plant species. Among host plant families, Fabaceae showed the greatest richness of insect gall morphotypes. We found that galling species richness was lower in palm swamp forest than in white-sand forests, which can be explained by the lower richness of plants in this type of vegetation. However, we found no evidence of greater richness in xeric habitats (e.g., white-sand dry forest) than in more mesic vegetation (terra firme forest), contradicting the hypothesis of hygrothermal stress. We also found that plant species richness was positively influenced with the richness and abundance of galling species, regardless of vegetation type. Galling insect species composition differed significantly between vegetation types, similarly to the floristic composition. Our findings show that the diversity of galling insects in the tropical rainforests of Peruvian Amazon are mainly influenced by host plant composition and host plant richness.

Abstract in Spanish is available with online material.

Los patrones de diversidad de insectos inductores de agallas tienden a estar influenciados tanto por características relacionadas con el hábitat y las plantas. Investigamos los patrones de distribución de insectos inductores de agallas en cuatro tipos de vegetación (bosque de tierra firme, bosque seco de arena blanca, bosque húmedo de arena blanca y bosque de pantano de palmas) de la Amazonía peruana para evaluar si la diversidad de insectos inductores de agallas (1) difiere entre diferentes tipos de vegetación y (2) depende de la riqueza de las plantas hospederas. En total, encontramos 11,579 agallas pertenecientes a 249 morfotipos de insectos inductores de agallas, distribuidos en 30 familias botánicas y 75 especies de plantas. Entre las familias de plantas hospederas, Fabaceae mostró la mayor riqueza de morfotipos de insectos inductores de agallas. Encontramos que la riqueza de especies inductoras de agallas era menor en el bosque de pantano de palmas que en los bosques de arena blanca, lo cual puede explicarse por la menor riqueza de plantas en este tipo de vegetación. Sin embargo, no encontramos evidencia de una mayor riqueza en hábitats xéricos (por ejemplo, bosque seco de arena blanca) que en vegetación más mesica (bosque de tierra firme), contradiciendo la hipótesis del estrés higrotermal. También encontramos que la riqueza de especies de plantas fue positivamente influenci

To simulate megafaunal (pig, tapir, and elephant) foraging, we cut 1228 saplings in a Sundaic rainforest. In total, 89%–94% of cut stems survived after 13.5 months. About 90% of naturally occurring break scars were at heights ≤1 m, implicating pigs, not elephants or tapirs, as the main source of stem damage in this forest.

Abstract in Malay is available with online material.

Conservation of mountain ecosystems can benefit from knowledge of habitats and their distribution patterns. This benefit is particularly true for diverse ecosystems with high conservation values such as the “Afromontane” rainforests. We mapped the vegetation of one such forest: the rugged Bwindi Impenetrable Forest, Uganda—a World Heritage Site known for its many restricted-range plants and animal taxa including several iconic species. Given variation in elevation, terrain and human impacts across Bwindi, we hypothesized that these factors influence the composition and distribution of tree species. To test this, detailed surveys were carried out using stratified random sampling. We established 289 georeferenced sample sites (each with 15 trees ≥20 cm dbh) ranging from 1320 to 2467 m a.s.l. and measured 4335 trees comprising 89 species that occurred in four or more sample sites. These data were analyzed against 21 digitally mapped biophysical variables using various analytical techniques including nonmetric multidimensional scaling (NMDS) and random forests. We identified six tree species assemblages with distinct compositions. Among the biophysical variables, elevation had the strongest correlation with the ordination (r² = 0.5; p < 0.001). The “out-of-bag” (OOB) estimate of the error rate for the best final model was 50.7% meaning that nearly half of the variation was accounted for using a limited set of variables. We demonstrate that it is possible to predict the spatial pattern of such a forest based on sampling across a highly complex landscape. Such methods offer accurate mapping of composition that can guide conservation.

Birds play key roles in forest dynamics, favoring the resilience of forests to cattle ranching. Generalist species may benefit from changes in the vegetation structure caused by cattle grazing while specialist species are usually negatively affected. Therefore, studying changes in taxonomic and functional bird diversity can provide valuable information in order to propose the sustainable cattle management practices. Here, we study the influence of different cattle management practices (Cattle Exclusion: FCE; Continuous grazing: FCG; Rotational grazing: FRG; Seasonal grazing: FSG) on the understory vegetation structure, and the bird taxonomic and functional diversity in humid Chaco forests of Argentina. Forests under grazing had an open (FCG) or semi-open (FRG and FSG) understory, whereas FCE presented a closed understory with higher plant richness. Generalized linear models revealed a decrease in bird richness and abundance under most cattle management practices compared to FCE. However, FRG was most similar to FCE in terms of vegetation structure and showed no differences in bird richness. FCE presented the lowest values of functional diversity while FCG and FRG showed the highest values. A fourth-corner analysis showed that FCE was associated with insectivorous species which forage and nest in the shrub layer, reflecting a possible loss of ecosystem services in forests with cattle grazing. We propose FRG as the most appropriate cattle management option and the least detrimental to bird assemblages. However, maintaining protected areas that exclude cattle ranching activities will be key to strike a balance between the conservation of most specialist species and beef production.

Abstract in Spanish is available with online material.

Las aves desempeñan un rol clave en la dinámica de bosques, favoreciendo la resiliencia de los bosques al pastoreo del ganado vacuno. Las especies generalistas pueden beneficiarse de los cambios en la estructura de la vegetación causados por el pastoreo del ganado, mientras que las especies especialistas suelen verse afectadas negativamente. En este sentido, estudiar los cambios en la diversidad taxonómica y funcional de las aves puede proporcionar información valiosa para proponer prácticas de manejo ganadero sustentables. Aquí, estudiamos la influencia de diferentes prácticas de manejo ganadero (Exclusión de ganado: FCE; Pastoreo continuo: FCG; Pastoreo rotacional: FRG; Pastoreo estacional: FSG) sobre la estructura de la vegetación del sotobosque y la diversidad taxonómica y funcional de las aves en los bosques húmedos del Chaco de Argentina. Los bosques bajo pastoreo tuvieron un sotobosque abierto (FCG) o semiabierto (FRG y FSG), mientras que los FCE presentaron un sotobosque cerrado con mayor riqueza de la vegetación. Los modelos lineales generalizados revelaron una disminución en la riqueza y abundancia de aves bajo la mayoría de las prácticas de manejo ganadero en comparación con FCE. Sin embargo,

Using remote-sensing camera traps, we assessed if large fallen trees serve as natural bridges facilitating the movement of mammals between river banks. We recorded 12 species of mammals using fallen trees to cross rivers. Additionally, the use of fallen trees was more pronounced during the rainy than the dry season.

Abstract in Portuguese is available with online material.

The Andes are a major dispersal barrier for lowland rain forest plants and animals, yet hundreds of lowland tree species are distributed on both sides of the northern Andes, raising questions about how the Andes influenced their biogeographic histories and population genetic structure. To explore these questions, we generated standardized datasets of thousands of SNPs from paired populations of 49 tree species co-distributed in rain forest tree communities located in Panama and Amazonian Ecuador and calculated genetic diversity (π) and absolute genetic divergence (d_XY) within and between populations, respectively. We predicted (1) higher genetic diversity in the ancestral source region (east or west of the Andes) for each taxon and (2) correlation of genetic statistics with species attributes, including elevational range and life-history strategy. We found that genetic diversity was higher in putative ancestral source regions, possibly reflecting founder events during colonization. We found little support for a relationship between genetic divergence and species attributes except that species with higher elevational range limits exhibited higher d_XY, implying older divergence times. One possible explanation for this pattern is that dispersal through mountain passes declined in importance relative to dispersal via alternative lowland routes as the Andes experienced uplift. We found no difference in mean genetic diversity between populations in Central America and the Amazon. Overall, our results suggest that dispersal across the Andes has left enduring signatures in the genetic structure of widespread rain forest trees. We outline additional hypotheses to be tested with species-specific case studies.

We examined whether and how woody debris removal for domestic fuel affects carbon storage and soil properties in an Indian rainforest. Fuelwood removal reduced aboveground carbon stocks, increased soil bulk density, and possibly reduced soil phosphorus stocks. Equitably balancing this subtle trade-off between climate-regulating and vital, widely utilized provisioning functions, is a challenge for tropical forest research and management.

Bees and the ecosystem services they provide are vital to urban ecosystems, but little is understood about their distributions, particularly in the Asian tropics. This is largely due to taxonomic impediments and limited inventorying, monitoring, and digitization of occurrence records. While expert collections (EC) are demonstrably insufficient by themselves as a data source to model and understand bee distributions, the boom of community science (CS) in urban areas provides an untapped opportunity to learn about bee distributions within our cities. We used CS observations in combination with EC observations to model the distribution of bees in Singapore, a small tropical city-state in Southeast Asia. To address the restricted spatial context, we performed multiple bias corrections and show that species distribution models performed well when estimating the distribution of habitat specialists with distinct range limits detectable within Singapore. We successfully modelled 37 bee species, where model statistics improved for 23 species upon the incorporation of CS observations. Nine species had insufficient EC observations to obtain acceptable models, but could be modelled with the incorporation of CS observations. This is the first study to combine both EC and CS observations to map and model the occurrences of tropical Asian bee species for a highly urbanized region at such fine resolution. Our results suggest that urban landscapes with impervious surfaces and higher temperatures are less suitable for bee species, and such findings can be used to advise the management of urban landscapes to optimize the diversity of bee pollinators and other organisms.

There is great global interest in tropical forest restoration, but many restoration efforts are not effective. Here we argue for the importance of belowground processes in tropical forest restoration and provide suggestions of next steps to advance our understanding of belowground processes in tropical forest restoration success.

Large scale disturbances are known to significantly alter aspects of both species diversity and ecosystem function. In the Caribbean, hurricane events are a significant form of disturbance, the effects of which have been shown to alter food web function, especially in the terrestrial environment. Although hurricanes have been studied from a variety of their effects on ecosystems, there is little research on how these storms affect species along elevational gradients. Within terrestrial habitats, ants form the basis of many food webs, being both numerically dominant and functioning in a variety of roles within the food web. On September 20th, 2017 Hurricane Maria, a category 4 storm, crossed over the island of Puerto Rico, causing significant damage to both human and natural systems. We collected data on ant abundance and composition from 150 samples of leaf litter along a 700 m elevational gradient during June the year of and after the storm event. Ant abundance increased by 400% after the storm with many common ant species seeming to benefit, especially at lower elevations. There were subtle changes in ant richness, with declines generally after the storm, but yet again this response was dependent on elevation. This is one of the first studies to consider how terrestrial insect communities are affected by large hurricane events across elevations, and our results are in contrast to past work showing declines in ant abundance after such storms.

Abstract in Spanish is available with online material.