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opencc-by-4.0Oct 2023View details →

Fig. 2 in Long-term changes in avian relative abundances in relation to human disturbance in a tropical dry forest in central Myanmar

Fig. 2. Annual rainfall measured adjacent to Chatthin Wildlife Sanctuary 1999–2020.

opencc-by-4.0Oct 2023View details →

Fig. 3. Forest cover within 300 in Long-term changes in avian relative abundances in relation to human disturbance in a tropical dry forest in central Myanmar

Fig. 3. Forest cover within 300 meters of bird survey points in 1999 and 2020.

opencc-zeroDec 2023View details →

Contrasting responses of fine root biomass and traits to large-scale nitrogen and phosphorus addition in tropical forests in the Guiana shield

Fine roots mediate plant nutrient acquisition and growth. Depending on soil nutrient availability, plants can regulate fine root biomass and morphological traits to optimise nutrient acquisition. Little is known, however, about the importance of these parameters influencing forest functioning. In this study, we measured root responses to nutrient additions to gain a mechanistic understanding of plant adaptations to nutrient limitation in two tropical forests in French Guiana, differing two-fold in their soil nutrient statuses. We analysed the responses of root biomass, mean root diameter (RD), specific root length (SRL), specific root area (SRA), root tissue density (RTD) and carbon (C), nitrogen (N) and phosphorus (P) concentrations in roots down to 15 cm soil depth after three years of N and P additions. At the lower-fertility site Paracou, no changes in root biomass or morphological traits were detected with either N or P addition, although P concentrations in roots increased with P addition. In the higher fertility site, Nouragues, root biomass and P concentrations in roots increased with P addition, with no changes in morphological traits. In contrast, N addition shifted root traits from acquisitive to more conservative by increasing RTD. A significant interaction between N and P in Nouragues pointed to stronger responses to P addition in the absence of N. Our results suggest that the magnitude and direction of root biomass and trait expression were regulated by soil fertility, corroborated by the response to N or P additions. At low fertility sites, we found lower plasticity in root trait expression compared to more fertile conditions, where N and P additions caused stronger and antagonistic responses. Identifying the exact role of mechanisms affecting root nutrient uptake in Amazon forests growing in different soils will be crucial to foresee if and how rapid global changes can affect their carbon allocation.

opencc-by-4.0Dec 2023View details →

List of references used in the bibliometric analysis of Chapter 2 - History of Research About the Tropical Brazilian Coral Reef Systems - Book: Brazilian Coral Reefs

This list contains 755 references related to coral reefs research. This list was obtained through a search for articles and book chapters in the databases Web of Science and Scopus, using the terms "reef" and "Brazil" in Title, Abstract and Keywords, added to references included from the authors own databases. The search was made in February, 12th 2021.

opencc-zeroDec 2023View details →

Diversity patterns along ecological succession in tropical dry forests: A multi-taxonomic approach

Evaluating the diversity of multiple taxa is fundamental to understand community assembly and to assess the integrity and functionality of tropical secondary forests. In this study, we analyzed the natural regeneration of tropical dry forests (TDFs) in three regions of Brazil using Hill-Simpson diversity, abundance and β-diversity of trees and five groups of insects (herbivores, fruit-feeding butterflies, ants, culicid mosquitoes and dung beetles). Sampling was conducted in 39 0.1 ha plots using a chronosequence approach (13 plots in early, intermediate and old-growth forests). We evaluated the contribution of three different levels to γ-diversity: α (within plots), β¹ (among plots) and β² (among successional stages), and further determined the relative importance of turnover (species replacement) and nestedness (differences in species number among sites) to β². Our results showed that, unexpectedly, the Hill-Simpson diversity was consistently higher in early than old-growth stages for all regions, but varied more widely in the intermediate stages. For each group separately, the same trend was observed for butterflies, ants, dung beetles and herbivores and did not differ among stages for mosquitoes. Successional differences in abundance were only detected for trees (increasing along the gradient) and for mosquitoes (decreasing). According to our expectations, the additive partitioning analysis showed that β2-diversity contributed more to γ-diversity than β1-diversity, when all taxa were considered together and for most of them separately (except for butterflies and dung beetles). Most of the β²-diversity was due to species turnover, but this contribution varied among groups and regions, with the highest turnover for herbivores and the lowest for dung beetles. Our results suggest that the Hill-Simpson diversity and changes in species composition (as given by β²-diversity) are better indicators of forest natural regeneration than raw species richness, corroborating previous studies with plants and animals.

Pattern and driver of the compositional variations in a tropical cloud forest: Comparing vascular epiphytes with terrestrial woody plants

β-diversity patterns (the compositional variations across sites) and their drivers are the major concerns of biodiversity research and conservation practices, whereas such information remains scarce for vascular epiphytes, especially in tropical forest communities. This study aimed to reveal the pattern and driving process of the compositional variations of vascular epiphytes in a tropical cloud forest on Hainan island, southern China, and their differences from those of terrestrial woody plants. To this end, we quantified their between-habitat compositional variations and distinguished the underlying components of β-diversity (nestedness and turnover). We then examined the relative roles of niche-based and neutral processes in driving the compositional variations by using a null model approach. Our results showed that the between-habitat compositional variations were significant for both plant assemblages and stronger in vascular epiphytes than in terrestrial woody plants. The turnover component of β-diversity was significantly stronger in terrestrial woody plants, accounting for 73.16%–80.08% of the variations. By contrast, the nestedness component was significantly stronger in vascular epiphytes and characterized 46.82%–67.5% of the variations. Besides, the compositional variations of both plant assemblages, especially terrestrial woody plants, were generally poorly fitted by the simulated niche-based scenarios but well fitted by the simulated neutral scenarios. Overall, the compositional variations of both plant assemblages were significant and mainly due to dispersal limitation, albeit to varying degrees. Hence, further studies of these plant assemblages at local scales should not be ideologically limited to the niche-based framework. Moreover, the stronger nestedness observed in vascular epiphytes suggests the greater importance of prioritizing conservation efforts in the species-rich habitats for these plants.

Butterfly community composition within a tropical urban landscape is influenced by habitat type and temperature

The specific factors that influence spatial community or population dynamics are often elusive, and even less known is the impact of tropical urban landscapes on diverse species community assemblages. To address this knowledge gap, we used a survey data set with 510 fruit‐feeding butterflies comprising 20 species across two heterogeneous habitats within a city in Nigeria. Next, we constructed generalised linear mixed models to understand the differential responses of the butterfly community to changes in environmental conditions across habitats. Butterfly species community assemblages significantly differed between the two urban habitats, with butterfly species significantly higher in the savannah woodland compared with the gallery forest due to the optimal daily temperatures of the savannah woodland. However, butterfly richness was lower in the gallery forest due to extreme environmental conditions. This study highlights that butterfly community changes in tropical urban landscapes are possibly responding to local microclimates and spatial heterogeneity across habitats. For evidence‐based conservation management of tropical butterfly biodiversity, there would be a need for a long‐term, extensive and systematic insect monitoring programme for butterflies across disturbed and undisturbed fragmented habitats harbouring diverse insect species.

Replication data for global population profile of tropical cyclone exposure during 2002 and 2019

Tropical cyclones have far-reaching impacts on livelihoods and population health that often persist years after the event. Characterizing the demographic and socioeconomic profile and the vulnerabilities of the exposed populations is essential to assess health and other risks associated with future tropical cyclone events. Estimates of exposure to tropical cyclones are often regional rather than global and do not consider population vulnerabilities. Here, we combine spatially resolved annual demographic estimates with tropical cyclone wind fields estimates to construct a global profile of the populations exposed to tropical cyclones between 2002 and 2019. We find that approximately 560 million people are exposed yearly and that the number of people exposed has increased across all cyclone intensities over the study period. The age distribution of those exposed has shifted away from children (under-5) and towards older people (over-60) in recent years compared to the early 2000s. Populations exposed to tropical cyclones are more socioeconomically deprived than those unexposed within the same country, and this relationship is more pronounced for people exposed to higher intensity storms. By characterizing the patterns and vulnerabilities of populations exposed to tropical cyclones, our results can help identify mitigation strategies and assess the global burden and future risks of tropical cyclones.

Data from: Temperature seasonality drives taxonomic and functional homogenization of tropical butterflies

To understand the potential impact of climate change on butterfly assemblages across a tropical island, we used thousands of museum records of diurnal Lepidoptera to model current (1970–2000) and forecast future (2061–2080) species distributions and combined these to test for taxonomic and functional homogenization. We then quantified climatic-mediated effects on current and forecasted taxonomic and functional composition and, specifically, whether temperature was a primary driver, as predicted by the temperature-size rule and the thermal melanism hypotheses. Finally, we measured wing traits important in thermoregulation (size and color) and determined trait-mediated changes in forecasted species distributions over time. Our models projected an increase in taxonomic and functional richness over time, and a decrease in taxonomic and functional turnover – a signature of biotic homogenization. Under future climate scenarios, models projected a decrease in wing length and an increase in wing brightness at higher elevations. One variable, temperature seasonality, was the strongest predicted driver of both the current spatial distribution and the projected percent change over time for not only wing traits, but also taxonomic and functional richness and turnover. This dataset contains wing trait data for 62 butterfly species of Puerto Rico, included in the study, measured on digitized museum specimens. Generally, 10 individuals of each species were measured, allowing for measurements of inter- and intraspecific wing trait variation. Traits include: wing length and width, and color metrics: intensity, hue, saturation, and brightness.

Data from: Comparative assessment of a novel fan box trap for collecting Anopheles farauti and culicine mosquitoes alive in tropical north Queensland, Australia

During preliminary mosquito surveys at Cowley Beach Training Area in north Queensland, Australia, it was found that the utility of the standard encephalitis virus surveillance (EVS) trap for collecting the malaria vector Anopheles farauti (Laveran) adults was compromised by the harsh tropical conditions. With the aim of increasing the survival rate of mosquitoes, we designed a downdraft fan box trap (FBT) that incorporated a screened fan at the bottom of the trap, so mosquitoes did not have to pass through a fan. The FBT was tested against the EVS and Centers for Disease Control (CDC) light traps, where mosquitoes do pass through a fan, and a nonpowered passive box trap (PBT). We conducted four trials to compare the quantity and survival of An. farauti and culicine mosquitoes were collected in these traps. Although not significant, the FBT collected more An. farauti than the EVS trap and PBT and significantly less An. farauti than the CDC light trap. However, the FBT improved on the CDC light trap in terms of the survival of An. farauti adults collected, with a significantly higher percentage alive in the FBT (74.6%) than in the CDC light trap (27.5%). Thus, although the FBT did not collect as many anophelines as the CDC, it proved to be superior to current trap systems for collecting large numbers of live and relatively undamaged mosquitoes. Therefore, it is recommended that FBTs be used for collecting An. farauti adults in northern Australia, especially when high survival and sample quality are important.

Woody debris removal modifies carbon stocks and soil properties in a fragmented tropical rainforest

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.

The interplay between defaunation and phylogenetic diversity affect leaf damage by natural enemies in tropical plants

<ol> <li>Natural enemies play an important role in controlling plant population growth and vegetation dynamics. Tropical rainforests host the greatest diversity of herbivores, from large mammalian ungulates to microscopic pathogens, generating and maintaining plant diversity.</li> <li>By feeding on the same resources, large mammalian herbivores may interfere with plant consumption and leaf damage by important enemy guilds such as invertebrate herbivores and pathogens, triggering indirect trophic cascades. However, the impact of local extinctions of large herbivores on plant-enemy interactions is relatively unknown.</li> <li>We experimentally tested the effects of defaunation of large mammalian herbivores (e.g., peccaries, tapirs, brocket deer; hereafter, large herbivores) on leaf damage of 3,350 understory plants in tropical rainforests of Brazil. We examined leaf damage in 10,050 leaves from 333 morphospecies by assigning the area consumed or damaged by five guilds of insect herbivores and leaf pathogens within 86 paired open-closed plots and investigated the joint effects of defaunation and plant phylogenetic diversity.</li> <li>Plants released from large herbivores had 9% less leaf damage; this difference was due to the lower leaf pathogens incidence (29%) rather than insect herbivory. Evolutionary Distinctness was similarly and positively correlated with leaf damage in all treatments, suggesting additive effects of defaunation and phylogenetic diversity. Total and pathogenic leaf damage (but not insect damage) decreased with plant richness across treatments, and large herbivores' exclusion resulted in increased plant species richness. This suggests that large herbivores' exclusion leads to a dilution of total and pathogens' leaf damage by increasing plant species richness.</li> <li>Our results suggest that large herbivores' indirect effects decrease the dilution potential of plant communities against pathogens and rather reinforce their top-down impact on vegetation, demonstrating a previously overlooked cascading effect of large herbivore extinction on forest ecosystems.</li> <li> Synthesis: The extinction of large mammalian herbivores can lead to a decrease in pathogen-driven leaf damage, a previously unknown indirect effect in forest ecosystems, which might have consequences for plant fitness and ultimately for plant diversity. Large herbivores and plant pathogens might have synergistic effects in regulating the diversity of plant communities in some of the most diverse ecosystems on Earth.</li> </ol>

Community science enhances modelled bee distributions in a tropical Asian city

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 urbanised 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 optimise the diversity of bee pollinators and other organisms.

Bromeliad populations perform distinct ecological strategies across a tropical elevation gradient

<ol> <li>The effect of environmental gradients on the remarkable diversity of mountain-associated plants and on the species' abilities to cope with climate change transcends species-specific strategies. For instance, our understanding of the impact of thermal gradients on ecological divergences in populations of widely distributed species is limited, although it could provide important insights regarding species' response to climate change.</li> <li>Here, we investigated whether populations of an endemic species broadly distributed across an elevation gradient employ unique or multiple divergent ecological strategies according to specific environmental conditions. We hypothesized that populations employ distinct strategies, producing a tolerance-avoidance trade-off related to the thermal conditions they experience across elevations.</li> <li>We conducted our research with 125 individuals of Pitcairnia flammea (Bromeliaceae) sampled from various elevations spanning from sea level to ~2,200 meters and cultivated under the same conditions. To assess specific ecological strategies of P. flammea populations across elevations, we examined leaf temperature, heat and cold tolerances, as well as other structural/morphological, optical, physiological, and biochemical leaf traits.</li> <li>We majorly observed that water-saving traits diminish as elevation increases while membrane fluidity, majorly associated with unsaturated and very-long-chain lipids, enhances. Low-elevation individuals of P. flammea invest in water storage tissues, which likely prevent excessive water loss through the intense transpiration rates under warming periods. Conversely, high-elevation plants exhibit increased membrane fluidity, a possible response to the stiffening induced by low temperature.</li> <li>Our results revealed a tolerance-avoidance trade-off related to thermal strategies of populations distributed across an elevation gradient. Low-elevation plants avoid excessive leaf temperature by investing in water-saving traits to maintain transpiration rates. High-elevation individuals, in turn, tend to invest in membrane properties to tolerate thermal variations, particularly cold events.</li> <li>Our findings challenge the conventional notion that plants' vulnerability to warming depends on species-specific thermal tolerance by showing diverse thermal strategies on populations across an elevation gradient.</li> </ol>

Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum

The global ocean's oxygen (O2) inventory is declining in response to global warming, but the future of the low-oxygen tropics is uncertain. We present new evidence for tropical oxygenation during the Paleocene-Eocene Thermal Maximum (PETM), a warming event that serves as a geologic analogue to anthropogenic warming. Foraminifera-bound nitrogen isotopes indicate that the tropical North Pacific oxygen-deficient zone contracted during the PETM. A concomitant increase in foraminifera size implies that oxygen availability rose in the shallow subsurface throughout the tropical North Pacific. These changes are consistent with ocean model simulations of warming, in which a decline in biological productivity allows tropical subsurface oxygen to rise even as global ocean oxygen declines. The tropical oxygen increase may have helped avoid a mass extinction during the PETM.

Data on arthropod abundance in tropical forest restoration plots with high or low plant phylogenetic diversity

Consideration of plant phylogenetic diversity in ecological restoration carries substantial potential, as communities with a greater diversity of lineages with older evolutionary histories can increase the diversity of niches and thus are likely to recover larger species networks than communities clustered in specific clades with reduced variation in functional traits. In this study, we experimentally assessed how arthropod communities were affected by the phylogenetic diversity of a set of tropical tree species. We established 12 experimental restoration plots with either high or low plant phylogenetic diversity, while maintaining constant the number of plant species. After one and three years, arthropods with different feeding habits (herbivores, predators, pollinators, and detritivores) were collected and identified as morphospecies or operational taxonomic units using metabarcoding techniques. We provide insights on the influence of plant phylogenetic diversity on arthropod abundance and species diversity, particularly among predator, pollinator, and detritivore common and dominant species, which increased with plant phylogenetic diversity. The trend, however, was the opposite for the diversity of herbivore common and dominant species, which decreased as plant phylogenetic diversity increased. These findings highlight the importance of considering plant species richness when designing restoration strategies, but also their evolutionary histories, as the same number of plant species can produce different outcomes for higher trophic levels, as a function of their phylogenetic relationships.

Effects of leaf silicon on drought performance of tropical tree seedlings

Elevated leaf silicon (Si) concentrations improve drought resistance in cultivated plants, suggesting Si might also improve the drought performance of wild species. Tropical tree species, for instance, take up substantial amounts of Si, and leaf Si varies markedly at local- and regional-scales, suggesting consequences for seedling drought resistance. Yet, whether elevated leaf Si improves seedling drought performance in tropical forests is unknown. To manipulate leaf Si concentrations, seedlings of seven tropical tree species were grown in Si-rich and -poor soil, before exposing them to drought in the forest understory. Survival, growth, and wilting were monitored. Elevated leaf Si did not improve drought survival and growth in any of the species. In one species, drought survival was reduced in seedlings previously grown in Si-rich soil, contrary to our expectations. Our results suggest that elevated leaf Si does not improve the drought resistance of wild tropical tree species. Elevated leaf Si may even reduce drought performance, suggesting differences in soil conditions influencing leaf Si may contribute to soil-related variation of tropical seedling performance. Furthermore, our results are at odds with most studies on cultivated species and show that alleviative effects of Si in crops cannot be generalized to wild plants in natural systems.

opencc-by-4.0Mar 2024View details →

Spring tropical cyclones modulate near-surface isotopic compositions of atmospheric water vapour at Kathmandu, Nepal

All these data have been published in a ACP paper. If you use these data in any conditions, please cite the following publicaiton: Adhikari, N., Gao, J., Zhao, A., Xu, T., Chen, M., Niu, X., and Yao, T.: Spring tropical cyclones modulate near-surface isotopic compositions of atmospheric water vapour at Kathmandu, Nepal, EGUsphere, https://doi.org/10.5194/egusphere-2023-2186, 2023.

opencc-zeroMar 2024View details →

Data from: Preference for mammalian urine is higher in the canopy than on the ground in a tropical rainforest ant community in Yunnan, China

Ants are among the most abundant groups of arthropods, and approximately half of all ant species are associated with forest canopies. The forest canopy environment is distinct from the understory and forest floor, and vertical stratification in environmental conditions shapes species assembly and organismal traits and behaviors across taxa in forest communities. Canopy ants are faced with a more nitrogen-limited environment compared with ground ants because of their reliance on nitrogen-poor plant and insect exudates. Despite prior work suggesting that some ant species consume mammalian urine and use symbiotic bacteria to extract nitrogen, we have little knowledge about the consumption of urine in canopy ants or the relative preference for urine between ground and canopy ants. We conducted an observational field experiment in a lowland tropical rainforest in southern China to test for vertical stratification in ant preference for sugar and urine, setting ground and canopy baited pitfall traps with the use of a canopy crane. We found distinct vertical stratification in the use of urine, with higher richness and abundance in sugar baits on the ground, and a higher abundance in urine baits in the canopy. Furthermore, the composition of captured ants differentiated according to both vertical stratum and bait type. This distinct vertical stratification of niche preference may represent an important case of niche partitioning that contributes to high ant species diversity in tropical rainforests as well as high species turnover between ground and canopy strata. The preference of canopy ants for mammalian urine also highlights the importance of interspecific interactions across highly unrelated animal taxa and emphasizes the need for a holistic understanding of biological networks to effectively conserve threatened tropical forest communities.