Brazilian Tropical Rainforest Research Articles

How large felids of South America are influenced by environmental and anthropogenic variables in the most degraded portion of the Amazon

AbstractWe evaluated the most relevant natural and anthropogenic factors for the occurrence and co‐occurrence of jaguars (Panthera onca) and pumas (Puma concolor) in the eastern Amazon, the most degraded portion of this tropical rainforest in Brazil. We found that in a context of high human pressure, a more significant amount of primary forest and more significant annual rainfall most positively influence the occurrence of jaguars. In contrast, pumas are negatively influenced by proximity to roads and positively by slope. Additionally, the presence of primary forest areas and high annual rainfall also favour the co‐occurrence of jaguars and pumas in the same areas. In contrast, open areas more related to anthropogenic zones disfavour the co‐occurrence of these two species in this degraded portion of the Amazon. Our results support landscape management for conserving big cat species in the Amazon and reinforce the importance of forest conservation for maintaining big cats in altered landscapes. Although these animals occur in open habitats, in the Amazon, these species are dependent on primary forests, as they are better‐structured habitats that maintain the capacity to support prey and shelter.

Spatio-Temporal Variations of Volatile Metabolites as an Eco-Physiological Response of a Native Species in the Tropical Forest.

This study evaluates the essential oil (EO) composition of Piper rivinoides Kunth, a shrub native to the Brazilian tropical rainforest, across different plant parts and developmental phases. The aim was to explore the chemical diversity of EO and its reflection in the plant's ecological interactions and adaptations. Plant organs (roots, stems, branches, and leaves) at different developmental phases were subjected to hydrodistillation followed by chemical analysis using Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Flame Ionization Detector (GC-FID). The results revealed a relevant variation in EO yield and composition among different plant parts and developmental phases. Leaves showed the highest yield and chemical diversity, with α-pinene and β-pinene as major constituents, while roots and stems were characterized by a predominance of arylpropanoids, particularly apiol. The chemical diversity in leaves increased with plant maturity, indicating a dynamic adaptation to environmental interactions. The study underscores the importance of considering the ontogeny of plant parts in understanding the ecological roles and potential applications of P. rivinoides in medicine and agriculture. The findings contribute to the overall knowledge of Piperaceae chemodiversity and ecological adaptations, offering insights into the plant's interaction with its environment and its potential uses based on chemical composition.

A comparison between time of exposure, number of pitfall traps and the sampling cost to capture ground-dwelling poneromorph ants (Hymenoptera: Formicidae)

Using effective survey protocols to address the effects of environmental change are key to saving time, resources and costs. Although exhaustive sampling in any location has been shown as impractical, biodiversity sampling projects must capture sufficient information to show how species assemblages change with the environmental variables. This study investigated time of exposure in the field and the number of pitfall traps that efficiently sampled poneromorph ants in 30 250 m long plots across an area of 25 km2 of tropical rain forest in Brazil. The treatments used for the surveys included two days and 300 traps, 14 days and 300 traps, 14 days and 750 traps, and were considered the minimum, intermediate and maximum sampling efforts, respectively. We characterized each assemblage of ants in relation to a gradient of soil texture, terrain slope and leaf and branch litter volume, and then tested whether the ecological relationships observed with the maximum effort were comparable to data on intermediate and minimum sampling efforts. We also estimated the cost-effectiveness of using the protocols in survey programs. The assemblage of species sampled during 14 days was similar to the assemblage captured during two days, indicating that the number of days influenced the assemblage similarity more than the number of sampling traps. All ecological patterns detected with the maximum effort were also captured with lesser sampling efforts. Overall, both the intermediate and minimum sampling efforts represented savings around 26˗40% of total project costs and 43˗45% of time to process the samples. We recommend that two days of trapping time combined with 300 pitfall traps is a highly effective shortcut for monitoring assessment, which can be applied to large-scale biodiversity surveys in tropical forests.

First record of galls in the tree fern Cyathea phalerata (Cyatheaceae) from a Tropical Rainforest in Brazil.

First record of galls in the tree fern Cyathea phalerata (Cyatheaceae) from a Tropical Rainforest in Brazil.

Asexual regeneration and its implications for local bryophyte establishment in a Brazilian tropical rain forest

Bryophyte spores commonly show ready germination under laboratory conditions and are assumed to be responsible for long-distance dispersal, but their role in plant establishment under field conditions is considered less important overall than asexual vegetative propagation. Local establishment from spores or vegetative propagules have not been extensively examined among tropical bryophyte species, making it difficult to test hypotheses concerning their roles under natural conditions. I examined 11 bryophyte species from two sites in a tropical rain forest in Brazil to investigate the regenerative capacities of detached leaves (vegetative propagules) under laboratory and field conditions. Spore germination and early gametophyte development were also analyzed for the most prolific spore-producing species. Detached leaves, in contrast to spores, promoted the most rapid plant local establishment, and performed similarly under both culture conditions. Most prolific spore-producing species did not necessarily demonstrate the lowest leaf-regeneration rates. Roles of detached leaves in the persistence strategies of bryophyte species from the Brazilian Atlantic rain forest (especially the dioecious mosses Leucoloma serrulatum Brid., Leucobryum clavatum Hampe, and Pyrrhobryum spiniforme (Hedw.) Mitt.) are reported for the first time, and information concerning the production and germination of spores under field conditions likewise contributes to our understanding of the roles of spores in bryophyte establishment.

Nematode Fauna of Tropical Rainforest in Brazil: A Descriptive and Seasonal Approach.

Studies of nematode assemblages in natural ecosystems can contribute to better understanding of the occurrence, relevance, and ecology of plant-parasitic and other soil nematodes. Nematode assemblages and environmental parameters (organic matter, water content (WC), bulk density (BD), total porosity (Po), soil respiration, and soil texture) were investigated in two seasons (rainy and dry) in two forest areas of the Zona da Mata, Pernambuco State. The aim of our research was to evaluate the heterogeneity between two locations and seasons in the Brazilian Atlantic Forest. Structure and composition of the nematode assemblages differed between areas and across time. Rhabditidae dominated the rainy season in both forest soils. Rarefaction curves (RC) suggest that sampling to detect more nematode taxa should be more intensive in the rainy season. The forest soils have complex, stable soil food webs with high connectance and decomposition channels dominated by bacteria. The predator-prey relationships were not affected by changes in soil properties that fluctuate with time.

Conocimiento etnoagrícola al borde de la desaparición: el caso de una comunidad de la Mata Atlántica brasileña

This paper aims to survey ethnoagricultural knowledge by a community living in an area of Atlantic tropical rainforest in Brazil. Interviews were conducted to 20 persons who are still related to the use of plants. All of them had cultivated rocas in the past, activity they reported to have abandoned due to changes in environmental law, tourism activities and lack of land for planting. There is still a rich ethnoagricultural memory based on the traditional practices of cultivation of plants, management of the land, and the observation of nature. However, this knowledge is rapidly disappearing albeit its high socioenvironmental value and its recognized tangible and intangible biocultural heritage.

Can soil types explain species distributions? Evaluating the woody understory component of a tropical forest in Brazil

We examined the structural and distribution patterns of woody species in the understory community of a Brazilian tropical rain forest in relation to two different soil types having distinct textures and chemical compositions. Plots were installed in five areas with clayey and in five with sandy soils, representing the main soil types in the region of the Una Biological Reserve, BA—Brazil (15°00′–15°20′S and 39°00′–39°15′W). Plant assemblages growing on those two soil types were sampled using the RAPELD methodology. A total of 1233 individuals were found on clayey soils (belonging to 303 species) and 1293 individuals on sandy soils (belonging to 320 species). No significant differences were observed among these two sets of plants in relation to their species compositions, abundances, species richness, heights, densities, or maximum diameter. Both plant communities had high alpha and beta diversity levels. Despite the apparent unstructured organizations of the communities and the lack of strong niche differentiation, we did not find evidence of ecological drift through processes such as random differentiation or increased dissimilarity with increasing distances. A combination of high species richness and high turnover rates as part of a much larger community may explain the results. The four most abundant species were likewise the most abundant on both soil types. This study contributed in identifying sets of species that respond well to local edaphic conditions and can be considered for restoration projects.

AFLP marker analysis revealing genetic structure of the tree Parapiptadenia rigida (Benth.) Brenan (Leguminosae-Mimosoideae) in the southern Brazilian Tropical Rainforest

Parapiptadenia rigida is a tropical early secondary succession tree characteristic of the Tropical Atlantic Rainforest. This species is of great ecological importance in the recovery of degraded areas. In this study we investigated the variability and population genetic structure of eight populations of P. rigida. Five AFLP primer combinations were used in a sample of 159 individuals representing these eight populations, rendering a total of 126 polymorphic fragments. The averages of percentage of polymorphic loci, gene diversity, and Shannon index were 60.45%, 0.217, and 0.322, respectively. A significant correlation between the population genetic variability and the population sizes was observed. The genetic variability within populations (72.20%) was higher than between these (22.80%). No perfect correlation was observed between geographic and genetic distances, which might be explained by differences in deforestation intensities that occurred in these areas. A dendrogram constructed by the UPGMA method revealed the formation of two clusters, these also confirmed by Bayesian analysis for the number of K cluster. These results show that it is necessary to develop urgent management strategies for the conservation of certain populations of P. rigida, while other populations still preserve reasonably high levels of genetic variability.

Reproductive phenology of bryophytes in tropical rain forests: the sexes never sleep

Events of the sexual reproductive cycle of 11 bryophyte species (mosses and liverworts with monoicous and dioicous sexual conditions) were described for two different sites (montane and sea level) of a Brazilian tropical rain forest, during a 15 month-period. The sex expression of many species was continuous over the whole period, irrespective of the seasons and the forest sites. The specific sexual conditions of dioicous species did not change, but synoicous species had strategies to increase the chances of out-crossing, bearing unisexual branches in addition to bisexual ones. The pattern of gametangia and sporophyte development was different among the species, but the same between the sites. There was a seasonal effect on the maturation of gametangia and sporophytes. Male gametangia were mostly mature by the end of the dry season. Fertilization occurred during the wettest months and sporophytes developed during the dry season, dispersal of spores mostly towards the end of the dry season. Female gametangia were receptive over the whole period, with many mature gametangia before the start of the rainy season. Male gametangia, in contrast to female, took longer to develop and aborted in high numbers. Bryophytes in tropical rain forests are favored by wet weather and mild temperatures. Similar reproductive phenological patterns were found in different habitats with minor variations.

Genetic structure of Partamona helleri (Apidae, Meliponini) from Neotropical Atlantic rainforest

Stingless bees of the genus Partamona are distributed from southern Mexico to southern Brazil. This genus has been subject to different approaches to solve questions concerning general biology, taxonomy, systematics and biogeography, but population studies applying molecular techniques are inexistent. We analyzed the genetic structure of P. helleri across its geographic distribution along the coastal Atlantic tropical rainforest in Brazil. Ten mtDNA haplotypes were observed in 47 colonies of P. helleri of which some were exclusive and others shared among geographic sub-groups. Statistical analysis showed high genetic differentiation between geographic areas sampled. Fragmentation of the Atlantic forest during Pleistocene glaciations is discussed as a possible cause of the present haplotype distribution and frequency.

Long-term trends in nitrogen isotope composition and nitrogen concentration in brazilian rainforest trees suggest changes in nitrogen cycle.

Direct or indirect anthropogenic effects on ecosystem nitrogen cycles are important components of global change. Recent research has shown that N isotopes in tree rings reflect changes in ecosystem nitrogen sources or cycles and can be used to study past changes. We analyzed trends in two tree species from a remote and pristine tropical rainforest in Brazil, using trees of different ages to distinguish between the effect of tree age and long-term trends. Because sapwood differed from heartwood in delta(15)N and N concentration and N can be translocated between living sapwood cells, long-term trends are best seen in dead heartwood. Heartwood delta(15)N in Spanish cedar (Cedrela odorata) and big-leaf mahogany (Swietenia macrophylla) increased with tree age, and N concentrations increased with age in Cedrela. Controlling for tree age, delta(15)N increased significantly during the past century even when analyzing only heartwood and after removing labile N compounds. In contrast to northern temperate and boreal forests where wood delta(15)N often decreased, the delta(15)N increase in a remote rainforest is unlikely to be a direct signal of changed N deposition. More plausibly, the change in N isotopic composition indicates a more open N cycle, i.e., higher N losses relative to internal N cycling in the forest, which could be the result of changed forest dynamics.

Molecular and morphological characterization of heterorhabditid entomopathogenic nematodes from the tropical rainforest in Brazil

Despite massive losses of primary forest, the Amazonian rainforest remains an extremely rich source of biodiversity. In recent years, entomopathogenic nematodes (EPNs) have been isolated from soil in various parts of the world and used successfully as biological control agents against numerous insect pests. Therefore, a sampling in the rainforest of Monte Negro, Rondônia, Brazil was conducted with the aim of discovering new strains and/or species of EPNs for future development as biological control agents. From 156 soil samples taken at nine collecting sites, 19 isolates were obtained, all of them belonging to the genus Heterorhabditis. Four strains were subjected to detailed morphological and molecular evaluation. Based on morphometrics and internal transcribed spacer (ITS) sequence data, the strains LPP1, LPP2 and LPP4 were identified as Heterorhabditis indica, whereas LPP7 was considered Heterorhabditis baujardi. Comparative analysis of the ITS1 sequence of H. indica and H. baujardi isolates showed a polymorphic site for the restriction enzyme Tth 111 that could be used to distinguish the two species. Consequently, strains LPP1, LPP2, LPP3, LPP4, and LPP9 were identified as H. indica, whereas LPP5, LPP7, LPP8 and LPP10 were identified as H. baujardi.

First record of natural infection of Marlierea edulis by the eucalyptus canker fungus Chrysoporthe cubensis

Eucalyptus is the most important plant genus for forest plantations worldwide, including Brazil where approximately 3 million ha are cultivated. Chrysoporthe cubensis (formerly known as Cryphonectria cubensis) is the aetiological agent of eucalyptus canker, one of the most serious diseases of eucalypt. Although in the past this fungus was only known to attack eucalyptus and cloves, it is now known to attack other hosts in the Myrtaceae and Melastomataceae families (Wingfield, 2003; Seixas et al., 2004; Rodas et al., 2005). A host-range study involving wound inoculations with an isolate from eucalyptus indicated a potentially wide host range for this fungus, particularly within the order Myrtales (Seixas et al., 2004). Among the species found susceptible in this test was Marlierea edulis, popularly known in Brazil as ‘cambucá’. This is a large, native tree of the Brazilian tropical rainforest and a minor fruit tree occasionally grown as a curiosity in orchards. Recently, M. edulis was found in the field (Saquarema, State of Rio de Janeiro, Brazil) showing typical canker symptoms: necrotic wounds with cracking and flaking of the bark that led to branch death. Diseased tissue showed abundant, black, spine-like perithecial ostioles. The fungus had the typical morphology of C. cubensis: ascomata perithecial, subglobose 205–445 × 220–440 µm, ostioles rostrate 300–750 × 65–125 µm; asci unitunicate, clavate 15–28 × 3–5 µm; ascospores ellipsoid, 5–7 × 1–3 µm, one-septate and hyaline. A sample was deposited in the local herbarium (VIC 27828). Wound inoculations of an isolate obtained from this host using the bark-replacement method (Ferreira, 1989) on adult, healthy specimens of both M. edulis and Corymbia citriodora (=Eucalyptus citriodora) resulted in typical canker symptoms and abundant formation of sporulating C. cubensis perithecia after 3 weeks. This is the first record of natural infection by this fungus on M. edulis, and the third native host for this fungus to be found in the field in Brazil. This finding confirms the susceptibility under natural conditions of plants included in the host-range study performed by Seixas et al. (2004). The demonstration of pathogenicity of an isolate obtained from M. edulis to eucalyptus represents additional evidence for the hypothesis that native plants serve as reservoirs for eucalyptus canker outbreaks in Brazil.

Effects of Forest Fragmentation on Pteridophyte Diversity in a Tropical Rain Forest in Brazil

The impacts of forest fragmentation on the pteridophyte communities of the Una region of Bahia, Brazil, were investigated by comparing species richness and ensemble diversity among areas of large forest fragments (>900 ha), small forest fragments (<100 ha), and landscape matrix. We inventoried the pteridophytes below 1 m in height in interiors of small fragments, interiors of large fragments (control areas), edges of fragments, edges of continuous forest, capoeiras (initial stages of forest regeneration) and cabrucas (cocoa plantations). All ferns were collected following the plot method (plots of 120 · 10 m, each). Sampling units were established in the six main ecotypes of the Una region. These units were allocated within three sampling blocks of 5 per 5 km, which were chosen in order to include the largest forest patches that still remain. Results suggest that fragmentation has a negative impact on species richness at the matrix and the edges of forest remnants. A similar negative matrix end edge effect is reported for diversity of those sites measured by the a Log-series Index. However, small forest fragments have pteridophyte species richness and diversity rates similar to large ones so they should be considered of utmost importance to the conservation of forest-related species in the region.

Airborne P-band SAR applied to the aboveground biomass studies in the Brazilian tropical rainforest

The objective of this study is to evaluate the relationship between the response ( σ°) of airborne P-band Synthetic Aperture Radar (SAR) polarimetric data versus biomass values of primary forest and secondary succession. To ensure that different landscapes of “Terra firme” tropical forest of the Brazilian Amazon were represented, a test-site was selected in the lower Tapajós river region (Pará State). The microwave signals from the P-band polarimetric images were related to the aboveground biomass data by statistical regression models (logarithmic and polynomial functions). In the field survey, physiognomic and structural aspects of primary forest and regrowth were collected and afterwards the biomass was estimated using allometric equations based on dendrometric parameters. As an example of the potential use of P-band polarimetric images, they were classified by a contextual classifier (ICM), whose thematic stratification of land use/land cover was associated with biomass class intervals for mapping purposes. The main objective of this P-band experiment is to improve this tool for regional mapping of Amazon landscape changes, due to the growing rate of land use occupation.

Multitemporal analysis of land use/land cover JERS-1 backscatter in the Brazilian tropical rainforest

The temporal evolution of L-band microwave backscatter for several land cover types in the Tapajos National Forest is analysed using JERS-1. Five images were acquired from 1993 to 1997. Samples of the studied land cover types were identified after analysis of a Landsat Thematic Mapper (TM) dataset of 12 images obtained from 1984 to 1999. The following land cover types were investigated: bare soil, agriculture, pastures, forest regrowth from 1 to 23-year-old and primary forest. Backscatter behaviour of regrowth stands is influenced by the previous land use and by human impacts such as fire and selective logging. This selective logging can be mechanized or not, because people who live in the Amazon usually cut trees to build houses, bridges, fences, etc. Backscatter of young regrowth stands on sites immediately abandoned after slash and burn increases at a faster rate than young regrowth on sites abandoned after some years of agriculture. Backscatter of old regrowth stands also behaves differently where there are disturbances such as fire or selective logging. In the presence of such disturbances, one finds an oscillating pattern over time, while undisturbed forest shows either a progressive trend or a stable pattern, depending on the age of the stand.

Diffusion of Sustainable Agriculture in the Brazilian Tropical Rain Forest: A Discrete Choice Analysis

Diffusion of Sustainable Agriculture in the Brazilian Tropical Rain Forest: A Discrete Choice Analysis

Ligninolytic activity of tropical rainforest basidiomycetes

A total of 116 strains of Brazilian tropical rainforest basidiomycetes were evaluated in terms of their ability to oxidize the dye rhemazol brilliant blue R (RBBR) and guaiacol. Laccase and peroxidase activities were detected by the drop test using solutions of α-naphthol and pyrogallol, respectively. RBBR and guaiacol oxidation occurred in 96.6 and 87.1% of the strains tested, respectively. One hundred strains oxidized both substrates. In the drop test, most strains presented laccase (96.6%) and peroxidase (92.2%) activity. The quick screening method used here can be useful to identify ligninolytic fungal strains to be used in various biotechnological applications.

Carbon Dioxide Uptake by an Undisturbed Tropical Rain Forest in Southwest Amazonia, 1992 to 1993

Measurements of carbon dioxide flux over undisturbed tropical rain forest in Brazil for 55 days in the wet and dry seasons of 1992 to 1993 show that this ecosystem is a net absorber of carbon dioxide. Photosynthetic gains of carbon dioxide exceeded respiratory losses irrespective of the season. These gains cannot be attributed to measurement error, nor to loss of carbon dioxide by drainage of cold air at night. A process-based model, fitted to the data, enabled estimation of the carbon absorbed by the ecosystem over the year as 8.5 ± 2.0 moles per square meter per year.