Assemblages In Tropical Forests Research Articles

Ant diversity sampling in the Brazilian Amazon: a comparison of litter collection and pitfall trapping

Introduction: Ants in tropical forests are a hyper-diverse group that plays important ecological roles. Several studies on tropical forests have used different sampling protocols to capture soil ants, making it difficult to compare responses and patterns of diversity between studies. Thus, research that compares different well-structured and standardized sampling methodologies to adequately estimate the richness of ant species in tropical forests is necessary. Objective: In this study, we examined the combination of catches with pitfall traps with and without baits and litter collections for soil ant sampling. Methods: In the fall traps, we use two baited (sardines and bananas) and one non-baited. For the manual collections (litter sampling), the litter and only the topsoil of the loose soil were collected. Results: We found that traps containing sardine baits collected a greater abundance of ants, whereas non-baited traps collected a greater richness of ant species. On the other hand, litter collections captured the largest number of exclusive species, presenting a different species composition from the pitfall traps (with and without baits). In general, baited traps showed greater abundance in more degraded locations, while manual collections and unbaited pitfalls captured more individuals in preserved environments. Conclusions: Our results provide evidence that, for accurate sampling of soil ant assemblages in tropical forests, the use of different methodologies is necessary to capture a greater diversity of species because the methods differ in effectiveness according to habitat.

The diversity of foliicolous lichens on ferns in two Brazilian tropical forests

A more complete picture of the function of plants in ecosystems results from understanding biotic interactions and this study examined the interactions between ferns and foliicolous lichens. A sampling method involving 15-h walks in each of two tropical forests in Brazil was employed to assess foliicolous lichen diversity on ferns. The nature of foliicolous lichen-fern interactions, and their relationship with forest types (lowland and submontane) and leaf traits (hairs and leaf area), was investigated. Eleven fern species were found to be hosts to 30 foliicolous lichen taxa. Telmatoblechnum serrulatum and Meniscium longifolium were considered the key hosts harboring a greater number (18 and 12) of lichen taxa, of which five taxa were restricted to these two ferns. Approximately 55% of the foliicolous lichens were found on a single fern host. Thicharia sp. A and Gyalectidium filicinum were the more interactive taxa, occurring on seven and ten host ferns, respectively. The forest type had no influence on the interactions. The foliicolous lichen-host fern network differed significantly from null expectations, and there was no sign of specialization. There was also no variation related to the presence of hairs on the sampled ferns (80% had glabrous leaves) and leaf hairs had no significant influence on lichen diversity. Furthermore, leaf area had no influence on the diversity of lichen species. Our results provide a first picture of diversity of foliicolous lichens on fern assemblages in tropical forests. However, there are uncertainties about the mechanisms driving these interactions so more research is needed.

Herpetological Assemblages in Tropical Forests of the Taguibo Watershed, Butuan City, Eastern Mindanao, Philippines

Tropical watershed ecosystems support heterogeneous habitats and diverse non-human species assemblages, together providing ecosystem services to humans. Amphibians and reptiles are recognized as sensitive indicators of ecosystem “health,” related to beneficial services (provisional, regulating, cultural, structural, functional) human societies receive from terrestrial watersheds. The Taguibo Watershed supplies fresh drinking water to Butuan City in the Caraga Region of northeast Mindanao Island. However, very little is known about the herpetofauna of the area. Here, we synthesize biodiversity data from historical (1971, 1979) and recent (2013, 2017) herpetological surveys from the region. We utilize specimen-associated occurrence records and natural history information to produce a species inventory, analyze their habitat utilization, and characterize diversity metrics to describe herpetological communities of the watershed – resulting in 44 species (27 new records). A number of historically-documented species persist, having partitioned riparian and terrestrial habitat types in dipterocarp and secondary-growth forests of Taguibo. Reptiles exhibit little overlap in the use of microhabitats – in contrast to amphibians, which exhibit either unique or frequently shared microhabitat substrates. In terrestrial microhabitats (not immediately associated with water), many newly-recorded reptiles and amphibians (particularly, of the genus Platymantis) partition space predictably – either occupying a single microhabitat or, in one species (a pit viper, Tropidolaemus subannulatus), two microhabitats. We anticipate that our initial characterization of Taguibo’s herpetofauna may serve as a baseline to promote further research and facilitate conservation initiatives. We emphasize the importance of primary sources – field-based surveys and re-surveys – and open-access biodiversity data served via online platforms that provide live, transparent access to original, unaltered data. Anthropogenic threats involving economic-driven activities present a need for field-based research in support of watershed management. Periodic, survey, and re-survey studies – continuously updating earlier work – are the most reliable, repeatable, and publicly-transparent use of biodiversity survey data in support of societal benefits and ecosystem services.

Sampling Flower Chafer Beetles (Coleoptera: Cetoniidae) in the Amazon Rainforest: The Role of Bait Types and Trap Installation Heights

The role of different bait types and trap installation heights for an accurate trapping of flower chafer beetles (Coleoptera: Cetoniidae) is still poorly understand worldwide, especially in the Neotropical region. Therefore, in this study, we evaluated how the type of bait and trap installation height can influence flower chafer beetle sampling in the Amazon rainforest. For this, we sampled flower chafer beetles monthly from June to December 2019 in five Amazon forest fragments, in Juína, Mato Grosso, Brazil. In each collecting fragment, we installed aerial traps at different heights (i.e., 1.5, 4.5, 7.5, and 10.5 m above ground) and randomly baited with 300 ml of each of the following bait types: banana + sugarcane juice mixture; pineapple + sugarcane juice mixture; beer; or red wine. We collected 412 individuals belonging to 12 species of Cetoniidae beetles. Traps baited with pineapple + sugarcane juice mixture captured greater abundance and species richness of flower chafer beetles. Moreover, traps at 4.5, 7.5, and 10.5 m caught a similar number of individuals and species, and significantly more than traps at 1.5 m. Thus, our results provide evidence that for an accurate sampling of flower chafer beetle assemblages in tropical forests, traps baited preferably with a ripe fruit (e.g., pineapple) and sugarcane juice mixture should are installed at least 4.5 m above ground.

Spatial and temporal structure of diversity and demographic dynamics along a successional gradient of tropical forests in southern Brazil.

Analysis of the structure, diversity, and demographic dynamics of tree assemblages in tropical forests is especially important in order to evaluate local and regional successional trajectories.We conducted a long‐term study to investigate how the structure, species richness, and diversity of secondary tropical forests change over time. Trees (DBH ≥ 5 cm) in the Atlantic Forest of southern Brazil were sampled twice during a 10‐year period (2007 and 2017) in six stands (1 ha each) that varied in age from their last disturbance (25, 60, 75, 90, and more than 100 years). We compared forest structure (abundance and basal area), species richness, alpha diversity, demographic rates (mortality, recruitment, and loss or gain in basal area), species composition, spatial beta diversity, and temporal beta diversity (based on turnover and nestedness indices) among stand ages and study years.Demographic rates recorded in a 10‐year interval indicate a rapid and dynamic process of species substitution and structural changes. Structural recovery occurred faster than beta diversity and species composition recovery. The successional gradient showed a pattern of species trade‐off over time, with less spatial dissimilarity and faster demographic rates in younger stands. As stands grow older, they show larger spatial turnover of species than younger stands, making them more stochastic in relation to species composition. Stands appear to split chronologically to some extent, but not across a straightforward linear axis, reflecting stochastic changes, providing evidence for the formation of a nonequilibrium community. Policy implications. These results reiterate the complexity and variability in forest succession and serve as a reference for the evaluation and monitoring of local management and conservation actions and for defining regional strategies that consider the diversity of local successional trajectories to evaluate the effectiveness of restoration measures in secondary forests of the Atlantic Forest biome.

Intercontinental comparison of liana community assemblages in tropical forests of Ghana and Malaysia

Intercontinental comparison of liana community assemblages in tropical forests of Ghana and Malaysia

Liana community assemblages in relation to human disturbance in a tropical forest in Ghana: implications for conservation

Although lianas are disturbance-adapted plants, there are conflicting reports about how human disturbance influences their community assemblages in tropical forests. The current study was conducted to determine the patterns of liana diversity and community structure following human disturbance, and examine the conservation implications in the Kakum National Park, Ghana. Liana diversity and community structure were investigated in thirty 40 × 40 m plots (15 plots/forest type) that were randomly demarcated in disturbed and undisturbed forests (secondary and primary forests, respectively). Furthermore, tree saplings and seedlings were counted in the two forests and related with liana abundance. The findings revealed that liana Shannon diversity index, abundance and basal area were significantly higher in the disturbed forest. Besides, these attributes correlated significantly with disturbance intensity. Dominance of several liana species varied between the forest types probably as a result of human disturbance. Abundance of tree sapling and seedling was significantly lower in the disturbed forest, and it related negatively and significantly with liana abundance in the disturbed forest. Tree regeneration was absent in areas where lianas formed thickets. Management of lianas in the disturbed forest may be needed as lianas appear to have impeded tree regeneration.

Can remnant frugivore species effectively disperse tree seeds in secondary tropical rain forests?

Seed dispersal by frugivores in tropical rain forests is important for maintaining viable tree populations. Over the years, vertebrate assemblages in tropical forests have been altered by anthropogenic disturbances, leading to concerns about the ability of remnant vertebrates to substitute for the lost or declining vertebrate populations. We compared vertebrate composition and frugivore visitation rates as an indirect measure of rate of seed dispersal in three tropical rain forests in Uganda, namely Mabira, Budongo and Kibale Forests. Mabira is highly disturbed, Kibale is little and Budongo is intermediate. The aim was to determine whether vertebrate assemblages in differentially disturbed forests had comparable abilities to disperse seeds and whether tree species were equally vulnerable to loss of seed dispersers. Assemblages of forest generalist species were similar in all forests, but specialists were less abundant in the heavily disturbed forest. Remnant frugivores in the heavily disturbed forest were mainly small-bodied species that spat seeds beneath fruiting trees compared to large-bodied species observed in the less disturbed forests that ingested and carried away the seeds. We postulate that the quantity of seeds dispersed in heavily disturbed forests is much reduced due to low visitation rates of frugivores and the absence of large frugivores that consume large quantities of fruit. The quality of seed dispersal is affected as well by the distance over which seeds are moved. Assessment of vulnerability of trees shows no evidence for disperser substitution for trees producing large fruits. Fruit trees with low nutritional contents and digestibility were least visited in frugivore-impoverished forests. The loss of large specialist frugivores is likely to affect recruitment of many trees, especially of species that cannot establish beneath adult conspecifics.

Effects of Forest Fragmentation and Habitat Degradation on West African Leaf‐Litter Frogs

Habitat degradation alters the dynamics and composition of anuran assemblages in tropical forests. The effects of forest fragmentation on the composition of anuran assemblages are so far poorly known. We studied the joint influence of forest fragmentation and degradation on leaf-litter frogs. We specifically asked whether the processes structuring leaf-litter anuran assemblages in fragmented forests are the same as those in continuous forests. We analyzed anuran assemblages with respect to habitat characteristics, including fragmentation and degradation parameters. In comparison with continuous forests, species richness and diversity were lower and assemblage composition was altered in forest fragments. These changes seemed to be mainly caused by habitat degradation rather than forest fragmentation. Availability of aquatic sites for breeding, vegetation structure (including those variables indicating degradation), and leaf-litter cover had the most influence on the presence of single species. The comparatively small impact of fragmentation on anurans might be due to the location of the study area; it still possessed large tracts of continuous forest. These forest blocks may stabilize the regional rainforest climate and thus weaken the effects of fragmentation.

Sampling termites in forest habitats: A reply to Roisin and Leponce

Abstract To characterize the structure and species density of termite assemblages in tropical forests, we developed a sampling protocol based on a single large quadrat (belt transect) that standardises sampling effort and area. Emphasizing the estimation of species richness, Roisin and Leponce (2004, Austral Ecology, 29: 637–46) recommend sampling numerous small quadrats, and varying the number of quadrats depending on local species density. However, their method would result in the loss of standardisation and speed, taking up to four times longer to collect and process the samples. We show that even for a subtropical forest with low species density, our protocol produces robust results.

Dead wood and saproxylic beetle assemblages in a semi-deciduous forest in Southern Benin

Saproxylic (dead wood associated) beetles play an important role in all forest ecosystems and are known to be highly susceptible to forest management and fragmentation. Contrary to temperate forests, there has been very little research on saproxylic beetle assemblages in tropical forests. In Africa, large tracts of natural forest have been converted to tree plantations (mainly exotic species) and cropland, and these land use changes are expected to have a dramatic effect on saproxylic beetle assemblages. In the Lama forest reserve in Southern Benin, we conducted an inventory of dead wood and the associated saproxylic beetle fauna, focusing on three different forest types, natural semi-deciduous forest, teak plantations and fuelwood plantations. The dead wood recorded included all coarse woody debris (CWD), standing dead trees (snags) and dead branches or stems on live trees (limbs). Saproxylic beetles were reared from dead wood of different decay stages and tree species, using emergence traps. Both the quantity and quality of dead wood resources differed greatly among natural forest and plantations. Average volumes were about 30, 4 and 1 m 3 ha −1 in natural forest, teak and fuelwood plantations, respectively. Dead wood of advanced decay was basically absent in plantations, due to wood-collecting activities of the local population. The overall species richness of saproxylic beetles was higher in natural forest, and detrended correspondence analysis (DCA) clearly segregated dead wood beetle assemblages from natural forest and plantations. Multiple regression found three significant predictors of the first ordination axis, the volumes of (a) recently dead wood; (b) large pieces of dead wood; and (c) coarse woody debris. Despite the overall paucity of dead wood, in particular the lack of strongly decayed wood, saproxylic beetle diversity in teak and fuelwood plantations was surprisingly high, providing evidence of the importance of dead wood and the potential of dead wood management for biodiversity conservation.

Sampling termite assemblages in tropical forests: testing a rapid biodiversity assessment protocol

Summary 1. Termites play a key role in decomposition processes in tropical ecosystems. Rapid assessment of local termite assemblages requires a standardized sampling protocol capable of producing an accurate picture of species composition. This paper evaluates the efficacy of a sampling protocol designed to assess termite species richness and functional diversity in tropical forests. 2. The protocol entails a 100 m long transect consisting of 20 sections (each 5 × 2 m). One hour of human sampling effort per section is used to search for and collect termites from dead wood, soil, termite nests and other microhabitats up to a height of 2 m above ground. The protocol was tested in three forest sites where the local termite fauna was already comprehensively documented. Two transects were run at Danum Valley (Sabah, Borneo), one at Pasoh Forest Reserve (Peninsular Malaysia) and one at Mbalmayo Forest Reserve (Cameroon). 3. At the three sites the transect samples contained 31–36% of the known local termite species pool. The taxonomic and functional group composition of the transect samples did not differ significantly from that of the known local fauna. The two transects run at Danum Valley gave very similar patterns, suggesting that the protocol produces consistent within‐site results. After sampling 20 sections, pseudoturnover between the two Danum transects had declined to a relatively low level. 4. The transect method is effective because it utilizes collecting expertise within a protocol that standardizes sampling effort and area. The protocol provides a much more rapid and cost‐effective method for studying termite assemblage structure than sampling regimes designed to estimate population abundances. It was demonstrated that one supervised training transect was sufficient to ensure the protocol was conducted with the required level of sampling efficiency. 5. The protocol offers a rapid tool for investigating spatial and temporal patterns of termite assemblage structure in tropical forest sites. Existing data also suggest that termites warrant further investigation as ecological indicators. Termite assemblage composition shows a strong response to habitat disturbance and may be indicative of quantitative changes in the decomposition process. The termite transect has potential as a useful addition to any suite of organisms recommended for monitoring functional processes in tropical forests.