Tropical Rainforest Research Articles

Development of a neutralizing monoclonal antibody targeting Bothrops atrox venom metalloproteinases.

Development of a neutralizing monoclonal antibody targeting Bothrops atrox venom metalloproteinases.

Lianas exhibit lower leaf drought resistance than trees in both tropical dry and wet forests in Thailand

Lianas exhibit lower leaf drought resistance than trees in both tropical dry and wet forests in Thailand

Mixed evergreen and deciduous forests boost local climate resilience, nutrient dynamics, and photosynthetic performance assessed by remote sensing

Mixed evergreen and deciduous forests boost local climate resilience, nutrient dynamics, and photosynthetic performance assessed by remote sensing

Exploring the Educational Potential of Mutualistic Interaction between Cynometra cauliflora and Arbuscular Mycorrhiza in PT Chandra Asri’s Biodiversity Park: A Content Analysis for High School Biology Learning

Arbuscular mycorrhizal fungi (AMF) form mutualistic interactions with plants, including Cynometra cauliflora (Namnam), a tropical indigenous species from the Fabaceae family. This study explores the educational potential of this biological relationship to enrich high school biology education under the Kurikulum Merdeka framework. Field research was conducted at PT Chandra Asri’s Biodiversity Park in Cilegon, Banten Province, Indonesia, an area with rich local biodiversity and a tropical rainforest climate. The study used a qualitative content analysis approach following an exploratory-descriptive model. Nine naturally growing C. cauliflora individuals were selected for morphological observations and root sampling. Morphological characteristics were documented following standard botanical protocols, while AMF colonization was assessed through root clearing, Phillips and Hayman staining method, and microscopic observation. The percentage of AMF colonization was calculated using the gridline intersect method. Habitat characterization to understand the ecological context. Curriculum analysis reviewed Indonesian biology standards, textbooks, and scientific literature to map potential integrations. Key concepts such as mutualism, nutrient cycling, biodiversity conservation, and plant physiology were identified for curriculum enrichment. The findings suggest that studying C. cauliflora and its AMF association can effectively support Capaian Pembelajaran (Learning Achievement Targets), fostering student skills in scientific methods, environmental awareness, and critical thinking. Incorporating local examples promotes contextual and inquiry-based learning, aligning with the spirit of the Kurikulum Merdeka and strengthening students’ ecological literacy. In conclusion, the mutualistic relationship between C. cauliflora and AMF offers a valuable, locally relevant scientific model for enhancing biology education. It bridges scientific knowledge, cultural understanding, and sustainability, preparing students for real-world ecological challenges.

Variation of canopy openness of tropical rainforests of Sri Lanka with altitude and azimuth angle

Variation of canopy openness of tropical rainforests of Sri Lanka with altitude and azimuth angle

A tropical rainforest biome once existed in India at the K-Pg: Evidence from ‘one-vessel’ arecoid palms

A tropical rainforest biome once existed in India at the K-Pg: Evidence from ‘one-vessel’ arecoid palms

Insights on the Paleoclimate and Paleoecology of an Early Miocene Hominoid Site: A Multiproxy Study From Koru, Western Kenya

AbstractEarly Miocene terrestrial ecosystems in eastern Africa were shaped by regional rifting, local, regional, and global climate change, and biogeography, which in turn influenced the evolution of hominoids and other vertebrates. Here, we present a multiproxy study focused on reconstructing the ecosystem structure and climate of the Koru 16 locality, which is a fossil‐rich Early Miocene (∼20 Ma) site in Kisumu County, Kenya. At Koru 16, the lithofacies consist of interbedded ash and weakly developed paleosols, indicating episodic volcanic disturbances from the nearby Tinderet volcanic complex. Paleosol features and elemental weathering estimates suggest warm, wet conditions. Over 1,000 fossil leaves from two quarries (∼5 m apart) yielded 18 morphotypes, with 55% of the morphotypes found at both quarries, reflecting local landscape heterogeneity. Leaf physiognomic methods estimate mean annual precipitation at ∼2,000 mm/yr and a mean annual temperature >25°C indicating a tropical climate. Leaf lifespan reconstructions suggest a semi‐deciduous forest. Leaf mass per area values align with modern tropical rainforests and seasonal forests, corroborated by tree stump casts indicating a frequently disturbed forest with patches of closed‐ and open‐canopy similar to modern primate‐supporting tropical forests. The vertebrate fauna included a medium‐sized pythonid, three ape species, and other typical Early Miocene mammals. This multiproxy result indicates that seasonally wet tropical forest environments played a role in the evolution of Early Miocene vertebrate communities and emphasizes the importance of site‐specific studies in assessing habitat heterogeneity in Early Miocene hominoid ecosystems.

Greenhouse gas flux measurements from agricultural sites within the Swiss FluxNet network

The Swiss FluxNet provides ecosystem scale flux data for the major land use types in Switzerland. While the current station network includes long-term eddy covariance flux measurements from two forest sites (mixed deciduous forest Lägeren and evergreen spruce forest Davos), three permanent grassland sites (Chamau, Früebüel and Alp Weissenstein) as well as three cropland sites (Oensingen, Tänikon and Forel) complement the network. In addition, the measurements cover an altitude gradient ranging from 393 to 1978 m.a.s.l. Carbon dioxide (CO2) and water vapor (H2O) fluxes are measured continuously at all sites, while nitrous oxide (N2O) and methane (CH4) fluxes are also quantified at some sites. Currently, 123 site-years of data are openly shared with FLUXNET. Ancillary meteorological and soil microclimate data are collected continuously as well; plant growth is routinely monitored at all agricultural sites, i.e., grasslands and croplands. Together with the management data, such continuous measurements allow integrated multi-year (Feigenwinter et al. 2023b) and multi-site (Zeeman et al. 2010) comparisons, identification of drivers for greenhouse gas (GHG) fluxes (Maier et al. 2022, Feigenwinter et al. 2023a), quantification of C sequestration (Emmel et al. 2018), as well as assessments of management practices towards sustainable agriculture (Fuchs et al. 2018). Here, we will present long-term CO2 fluxes (since 2004) as well as CH4 and N2O fluxes measured at the six agricultural Swiss FluxNet sites, i.e., three permanent grasslands and three croplands with their typical Swiss crop rotation. Moreover, the contribution of abiotic and biotic drivers to intra- and interseasonal variations in GHG fluxes will be discussed, potential trade-offs among climate mitigation goals identified, and the importance of management information emphasized. We encourage other research teams to use the open-access dataset, growing annually, and seek collaboration in integrated flux measurements worldwide.

Trends and drivers of long-term forest evapotranspiration in Switzerland

Evapotranspiration (ET) from forested ecosystems is a major component of the water cycle, influencing soil moisture, groundwater recharge, and streamflow. ET also modulates local and regional climate through latent heat exchange, affecting temperature and humidity in forest ecosystems. Because ET is tightly linked to photosynthesis, it also indicates forest stress from drought conditions, making it a key metric for assessing forest ecosystem health. However, long-term measurements of ET are rare, thus the effects of a warming climate on forest ET fluxes remain poorly understood. ET fluxes can be limited by a lack of water availability in the subsurface, forcing trees to close stomata and reduce transpiration. In periods of high atmospheric demand, vapor pressure deficit (VPD) can also induce stomatal closure. Furthermore, limited energy availability, i.e., reduced net radiation on cloudy days, constrains ET by limiting latent heat flux. Thus, more detailed analyses of the dominant drivers of ET fluxes based on long-term datasets may help to identify under which environmental conditions ET is limited in forest ecosystems. Here we present an comprehensive analysis of long-term evapotranspiration data from eddy covariance measurements from two different forest sites in Switzerland: a subalpine evergreen coniferous forest (CH-Dav) and a montane mixed deciduous forest (CH-Lae), both part of Swiss FluxNet (www.swissfluxnet.ethz.ch). H2O vapor fluxes have been measured using eddy covariance (EC) since 1997 and 2004 at the Davos and Lägeren sites, respectively. The Davos site is located in the eastern Swiss Alps at an altitude of 1639 m asl., has an average annual precipitation of 876 mm and a mean annual temperature of 4.3 °C. The EC system is installed at 35 m, above the canopy of Norway spruce (Picea abies (L.) Karst) trees of a mean age of approximately 100 years and an average tree height of 18 m. The Lägeren site is located in the eastern part of the Jura Mountains in Switzerland at an altitude of 682 m asl., has an average annual precipitation of 831 mm and a mean annual temperature of 8.8 °C. The EC system is installed at 47 m, above the canopy of a mixed forest, dominated by European beech (Fagus sylvatica L.; 40 % cover), ash (Fraxinus excelsior L.; 19 % cover) and sycamore maple (Acer pseudoplatanus L.; 13 % cover). In addition, at both sites, climate variables (i.e., precipitation, temperature, vapor pressure deficit, solar radiation) and soil water content at different depths (i.e., 5, 10, 25 and 50 cm) have been measured continuously at 30-min resolution. Using this long-term data collection, we analyzed changes in annual and seasonal ET fluxes and assessed the major drivers of ET fluxes across the two forest sites. analyzed changes in annual and seasonal ET fluxes and assessed the major drivers of ET fluxes across the two forest sites. To analyze the main drivers of ET fluxes, we used the SHapley Additive exPlanations (SHAP) framework, allowing to estimate the contribution from each potential driver variable to the response variable (i.e., daily ET fluxes). Analyzing long-term ET fluxes at Davos and Lägeren, we found considerable differences between the two forest sites. The subalpine Davos site received slightly higher precipitation and had a lower temperature compared to the Lägeren site, thus soil moisture and vapor pressure deficit were less important drivers of ET at Davos compared to Lägeren. Instead, ET limitations in Davos were mainly related to lower net radiation. At the montane Lägeren site, compound dry events combining soil water deficits and higher VPD triggered decreasing forest ecosystem ET fluxes during the growing season. Analyses of especially dry years (i.e., 2003 – only Davos, 2015, 2018 and 2022) indicated that the spruce dominated Davos site showed higher ET compared to average years, due to favorable growing conditions at this typically energy-limited subalpine site. However, we found that even at the Davos site, extended dry periods (i.e., as observed during the year 2018) lead to higher atmospheric demand and thus lower ET. Overall, the Lägeren site was more vulnerable to dry periods, leading to depletion of soil moisture storage and an increase of VPD, resulting in a significant reduction of ET in the especially dry years. Overall, our results indicate that i) forest ecosystems in low-elevation sites are already experiencing frequent periods of ET reduction due to water limitations in the soil and high atmospheric demand while ii) high elevation forest ecosystems might become more vulnerable when the durations of high atmospheric demand are extending over longer time periods as projected in a future climate.

Unusual Wingspan Records in Two Congeneric Pierid Butterfly Species Catopsilia pomona (Fabricius, 1775) and Catopsilia pyranthe (Linnaeus, 1758) from Rajgir Wildlife Sanctuary, Bihar, India

The Common Emigrant Catopsilia pomona (Fabricius, 1775) and the Mottled Emigrant Catopsilia pyranthe (Linnaeus, 1758) occur together throughout the Indian subcontinent in several forms. They are on the wing almost throughout the year in tropical evergreen forests and are absent during periods of water stress or cold in other parts of their distribution range, such as in the Himalaya or the Gangetic plains. Current study was conducted on butterflies during 2023-2025 in and around Rajgir Wildlife Sanctuary in Nalanda district, Bihar. During this study we recorded largest Catopsilia pomona (Common Emigrant) form 84 mm and the smallest Catopsilia pyranthe (Mottled Emigrant) 42 mm were found in Mukti-Dham, Rajgir, Nalanda, Bihar. Mean size of specimens from the population of Catopsilia pomona was X̄ = 79.9 mm (SE ± 0.90 mm, N=10) and Catopsilia pyranthe was X̄ = 48.3 mm (SE ± 0.98 mm, N=13).

More than fruity scents: Pollination biology, scent, and spectral reflectance of Annonaceae species

AbstractThe family Annonaceae possesses a broad array of floral phenotypes and pollination specializations, and are important in the plant‐pollinator interactions of tropical rainforests. Although there has been considerable effort to assess their interactions with pollinators, attempts to characterize their visual and olfactory communication channels are scarce. Here, we investigated the pollination biology of 12 Annonaceae species from five genera, viz. Meiogyne, Monoon, Polyalthia, Pseuduvaria, and Uvaria. Furthermore, their floral color was characterized by reflectance spectroscopy and floral odor chemistry was assessed using gas chromatography–mass spectrometry. Floral scent was further compared across the whole family using non‐metric multidimensional scaling plots to identify similarity in floral odor among species. The Meiogyne species are likely pollinated by small beetles; the Polyalthia and Pseuduvaria species are likely pollinated by beetles and flies; and the Uvaria species are likely pollinated by beetles and bees. Flowers of most species are UV non‐reflective and have various spectral reflectance profile across the remaining visible spectra. Multiple species produce floral odor resembling ripe fruits. The flowers of Meiogyne species and Polyalthia xanthocarpa emitted mostly branched‐chain esters, while flowers of Uvaria released mainly straight‐chain esters. The Pseuduvaria species instead emitted scent reminiscent of rotten fruits, largely consisting of 2,3‐butanediol. The inner petal corrugation in Meiogyne functions as a food reward, and the inner petal growth serves as a nectary gland for Pseuduvaria. Our study identifies the visual and olfactory cues of multiple Annonaceae species and provides insights into how Annonaceae flowers attract different guilds of pollinators.

Age-Dependent Composition and Diversity of the Gut Microbiome in Endangered Gibbon (Nomascus hainanus) Based on 16S rDNA Sequencing Analysis

The Hainan gibbon (Nomascus hainanus) is one of the most endangered primates globally, threatened by habitat destruction, genetic diversity loss, and ecological competition. In this study, given the critical role of the gut microbiota in host immune regulation and nutrient metabolism, we investigated the composition of and age-related variations in the gut microbiota in Hainan gibbons. Using 16S rRNA sequencing, we systematically investigated the gut microbial diversity of Hainan gibbons. We collected 41 fecal samples from Hainan Tropical Rainforest National Park, covering three age groups: juveniles (4–6 years), subadults (7–10 years), and elderly animals (≥13 years). This study found that microbiota composition changed significantly with age. Juveniles had higher microbial diversity and complexity, while subadults showed an increased abundance of Fibrobacter and Prevotella in their microbial communities, along with a Tax4Fun-predicted enrichment of functional genes related to energy metabolism, cell motility, and nervous system functions. LEfSe analysis identified statistically significant microbial taxa among different age groups, with Bacteroidota and Firmicutes being the dominant phyla across all groups with varying proportions. These results highlight the critical role of the gut microbiota in the health and adaptability of Hainan gibbons, offering insights for conservation strategies. The findings of this study are significant for understanding the changes in gut microbiota and their ecological functions across different life stages of endangered primates.

Análisis multicriterio para identificación de áreas prioritarias en la conservación y restauración de la Provincia de Pastaza, Ecuador

Pastaza Province, located in the Ecuadorian Amazon, is recognized for its high biodiversity due to its tropical rainforest climate and has been designated a Biosphere Reserve. This study aims to identify priority areas for conservation and restoration through a multi-criteria analysis using Geographic Information Systems (GIS). The Analytical Hierarchy Process (AHP) was applied to evaluate both qualitative and quantitative variables using Saaty's scale. Three main criteria were defined: Environmental, Socioeconomic, and Intrinsic. GIS tools such as Union, Intersect, and Area of Interest (AOI) were employed to map, by hectares, the forest and water areas that should be prioritized for conservation or restoration. The results include the proportion of each zone according to the established criteria, enabling an efficient spatial planning framework for ecological management in the region.

Assessment of Suitable Habitats and Identification of Key Protection Areas for Polyplectron katsumatae in Jianfengling, Hainan Province, China.

Polyplectron katsumatae is a rare and endangered species endemic to Hainan, China. It has long been regarded as a subspecies of the widely distributed Grey Peacock-Pheasant (Polyplectron bicalcaratum), a classification that has resulted in a paucity of targeted conservation studies and rendered efforts to protect and restore its populations and habitats exceedingly challenging. In this study, the Jianfengling section of Hainan Tropical Rainforest National Park was designated as the research area. We comprehensively utilized infrared camera monitoring data for P. katsumatae and other species, alongside habitat environmental factor data obtained through multiple monitoring approaches. An ensemble species distribution model (ESDM) was employed to evaluate the habitat suitability for four ground-dwelling bird species, including P. katsumatae, and to investigate their environmental preferences and competitive interactions during habitat selection. Subsequently, the Marxan model was applied to identify key protection areas for P. katsumatae. The results indicate that the suitable habitat for P. katsumatae is primarily distributed in the central, eastern, and certain southern areas of the study region, with low spatial overlap and minimal competition from the suitable habitats of the other three ground-dwelling bird species. However, due to anthropogenic disturbances and the inherently stringent habitat requirements of P. katsumatae, its overall suitable habitat area is limited, exhibiting a concentrated distribution overall with fragmented, small patches within it. Our study recommends designating the eastern and southern regions of the study area as key protection areas for P. katsumatae, thereby providing a robust baseline environment and policy support for the targeted protection of its habitat and the recovery of its populations.

Field Investigation of Thermal Comfort and Indoor Air Quality Analysis Using a Multi-Zone Approach in a Tropical Hypermarket

Indoor environmental quality (IEQ), encompassing thermal comfort and indoor air quality (IAQ), plays a crucial role in occupant well-being and operational performance. Although widely studied individually, integrating thermal comfort and IAQ assessments remains limited, particularly in large-scale tropical commercial settings. Hypermarkets, characterised by spatial heterogeneity and fluctuating occupancy, present challenges that conventional HVAC systems often fail to manage effectively. This study investigates thermal comfort and IAQ variability in a hypermarket located in Gombak, Malaysia, under tropical rainforest conditions based on the Köppen–Geiger climate classification, a widely used system for classifying the world’s climates. Environmental parameters were monitored using a network of IoT-enabled sensors across five functional zones during actual operations. Thermal indices (PMV, PPD) and IAQ metrics (CO2, TVOC, PM2.5, PM10) were analysed and benchmarked against ASHRAE 55 standards to assess spatial variations and occupant exposure. Results revealed substantial heterogeneity, with the cafeteria zone recording critical discomfort (PPD 93%, CO2 900 ppm, TVOC 1500 ppb) due to localised heat and insufficient ventilation. Meanwhile, the intermediate retail zone maintained near-optimal conditions (PPD 12%). Although findings are specific to this hypermarket, the integrated zone-based monitoring provides empirical insights that support the enhancement of IEQ assessment approaches in tropical commercial spaces. By characterising zone-specific thermal comfort and IAQ profiles, this study contributes valuable knowledge toward developing adaptive, occupant-centred HVAC strategies for complex retail environments in hot-humid climates.

Effects of nitrogen and phosphorus additions on soil particulate organic carbon through altering microbial decomposition in two tropical montane rainforests

Effects of nitrogen and phosphorus additions on soil particulate organic carbon through altering microbial decomposition in two tropical montane rainforests

Multiscale analysis of global variation in tree allometric relationships: parameter sets for global vegetation models

Abstract Global models of vegetation dynamics and remote sensing data products require allometric relationships governing trees’ size and shape to predict such quantities as vegetation spatial structure and biomass. However, empirical variation in allometric relationships poses a challenge for global scale models that rely on limited classifications of plant functional types (PFTs), as site-derived parameters often fail to apply appropriately out of sample. To identify empirical allometric variation at multiple scales salient to these global models, we analyzed trees from the global Tallo database, fitting allometric models to biome-continent and biome-PFT aggregations as well as to individual sites. Our results provide new insight into global allometric variability compared to Metabolic Scaling Theory (MST) for relations between height, stem diameter, crown radius, and crown volume. The degree of within-biome variation across continents depends on biome, with tropical rain forests exhibiting much less variation than temperate broadleaf forests. Moreover, the PFT can explain allometric divergence in similar climates. The scaling exponents of most biome-PFT groups fall below the MST predictions for both H-D and CR-allometry. Needleleaf trees have high H-D scaling exponents, while broadleaf trees have low H-D scaling exponents. Overall, leaf type played a more important role in determining height (H)-stem diameter (D) allometry than phenology in our biome-PFT analyses, corresponding closely to disparate scaling exponents in very arid groups. At the site level, we found a clear positive relationship between within-site 95th percentile tree height and H-D scaling exponent. We found the geographic scale of spatial correlation among H-D and CR-H scaling exponents to be significant for sites less than 250 km apart and to decline at greater distances. Finally, we demonstrated how these allometric relationships can be used to estimate allometric parameters for a model that predicts aboveground biomass from Global Ecosystem Dynamics Investigation (GEDI) lidar waveform measurements.

Topography mediates contrasting patterns of glomalin-related soil protein and its contribution to soil organic carbon in a tropical montane rainforest

Topography mediates contrasting patterns of glomalin-related soil protein and its contribution to soil organic carbon in a tropical montane rainforest

Molecular and acoustic evidence for large-scale underestimation of frog species diversity on New Guinea

Species are fundamental units in biology; however, information on species diversity and distribution remain scarce for most taxonomic groups, especially in tropical rainforests. Such knowledge gaps are particularly acute in amphibians, the most threatened group of vertebrates, in which new species continue to be described at a high rate. Herein, using molecular-based approaches, we provide estimates for species diversity of frogs (Anura) in New Guinea and nearby islands, one of the biologically most diverse regions of the world. We first characterised taxonomic and geographic sampling for all available mitochondrial DNA sequences from native frog species. This led us to identify important molecular sampling gaps in the western half of New Guinea that we partially filled by adding 534 new sequences (16S rRNA). Large territories remain uncharted, particularly in the westernmost part of the central cordillera of New Guinea. Using our 16S rRNA dataset, we then delimited Molecular Operational Taxonomic Units (MOTUs), a subset of which was bioacoustically analysed. From a total of 369 delimited MOTUs, we found that 190 could not be assigned to any taxon. Amongst these, 123 are represented by specimens collected in the western half of New Guinea and 19 were supported as distinct by bioacoustics, confirming that this portion of the island is home to many unrecognised species. Based on the estimated level of undescribed diversity in taxa and areas for which data are available, we extrapolate that New Guinea and neighbouring islands could host 800–1,200 frog species, with only 560 species described to date. We assembled the most comprehensive molecular dataset to date (16S rRNA) for frogs from New Guinea and neighbouring islands. We delimited 190 candidate species, of which 19 are supported by available bioacoustic data. We estimated the actual number of frog species on New Guinea and neighbouring islands to be between 800 and 1,200. Parts of New Guinea exhibit species-diversity levels comparable to similarly sized regions in Amazonia and Madagascar. Most unrecognised frog taxa in the region are likely confined to restricted geographical areas and, thus, likely sensitive to both land use and climate change.

Fossils of an endangered, endemic, giant dipterocarp species open a historical portal into Borneo's vanishing rainforests.

Asia's wet tropical forests face a severe biodiversity crisis, but few fossils record their evolutionary history. We recently discovered in situ cuticles on fossil leaves, attributed to the giant rainforest tree Dryobalanops of the iconic Dipterocarpaceae family, from the Plio-Pleistocene of Brunei Darussalam (northern Borneo). Studying these specimens allowed us to validate the generic identification and delineate affinities to living dipterocarp species. We compared the leaf cuticles and architecture of these fossil leaves with the seven living Dryobalanops species. The cuticular features shared between the fossils and extant Dryobalanops, including the presence of giant stomata on veins, confirm their generic placement. The leaf characters are identical to those of D. rappa, an IUCN red-listed Endangered, northern Borneo endemic. The D. rappa monodominance at the fossil site, along with Dipterocarpus spp. leaf fossils, indicates a dipterocarp-dominated forest near the mangrove-swamp depocenter, most likely in an adjacent peatland. The Dryobalanops rappa fossils are the first fossil evidence of a living endangered tropical tree species and show how analysis of in situ cuticles can help illuminate the poorly known floristic history of the Asian tropics. This discovery highlights new potential for fossils to inform heritage values and paleoconservation in Southeast Asia.