Rainforest Ecosystem Research Articles

Estimating feral cat (Felis catus) population density in eastern Australia’s subtropical rainforest using spatial capture-recapture incorporating unidentified individuals

Context Management of broadly distributed invasive species requires knowledge of population densities across multiple ecosystems. The feral cat (Felis catus) has a continental distribution in Australia and has caused many declines and extinctions; however, density estimates from several ecosystems are few or lacking. Camera trapping data coupled with spatially explicit capture–recapture analysis is a suitable approach for estimating cat densities. However, if a large portion of individuals cannot be identified, density estimation may be difficult and estimates may be too low. Aims We aimed to estimate the feral cat density and population size within the subtropical Gondwanan Rainforest of eastern Australia, an area with world heritage status and high biodiversity values, and in which cat density was not known. Methods We used feral cat data from a grid of 60 camera traps deployed over 305 days in Border Ranges National Park, totalling 18,300 camera trapping nights. We employed a ‘random thinning’ spatially explicit capture–recapture model that considered detections of both known and unknown feral cat identities. Our modelling included a primary detection history of identified individuals and a secondary detection history that included pelage type, which allowed us to account for individuals with homogeneous pelage types. Key results Feral cat density was estimated at 0.858 cats km−2 (95% HPDI 0.432, 1.385), which is much higher than the average feral cat density across the Australian continent of 0.27 cats km−2 (95% CI: 0.18–0.45). The probability of identifying unique individuals was low for black and tabby cats compared with other pelage types. Population sizes during the four survey periods were estimated to be similar, with posterior medians ranging from 197 to 202 individuals and 95% highest posterior density intervals ranging from 95 to 329 individuals within a ~234 km2 area. Conclusions Our study provides the first robust feral cat density estimate from a subtropical rainforest ecosystem. Implications Our results add to a growing body of literature that suggests feral cat densities are high in productive mesic reserves of eastern Australia. Management of feral cats in Gondwanan World Heritage Areas should be prioritised to limit impacts on narrow-range endemic species that are likely prey to feral cats.

Ecological communities in white‐sand Amazonian rainforests are sensitive to deforestation—A dung beetle case

Abstract Campinarana is a fragile white‐sand rainforest ecosystem in Amazonia, where mining activities have been an important driver of landscape transformation, threatening biodiversity. Despite its importance for biodiversity, few studies have investigated insects' response to environmental disturbance in campinaranas. Here, we assess the differences between the dung beetle assemblages of undisturbed and disturbed campinaranas. The studied campinaranas differ substantially in their vegetation structure, the disturbed one strongly affected by mining activities. Dung beetle taxonomic diversity, abundance, biomass, and assemblage structure (species' distribution and relative abundances) from total and functional group perspective and indicator species were recorded in undisturbed and disturbed campinaranas. A total of 1592 beetles belonging to 42 species were collected in undisturbed campinaranas and 459 beetles from 11 species in disturbed campinaranas. Undisturbed campinaranas encompassed higher diversity, abundance, number of indicator species, and biomass, and their assemblages' structure were distinct from disturbed campinaranas. The abundance of roller dung beetles was the only parameter that was not affected by habitat type. Our results suggest that undisturbed campinaranas host sensitive ecological communities, with most of the species unable to cope with the changes brought by mining activities. In addition, dung beetle species can be a useful indicator for monitoring environmental disturbance in campinaranas. Considering the extension of the latter across the Amazon, this study provides information to support public policies to mitigate losses caused by deforestation in this hyperdiverse area.

Water use efficiency in tropical plants based on a set of newly created leaf photosynthesis-related parameters

Water use efficiency (WUE) quantifies the amount of water expended per unit of dry leaf matter accumulated, reflecting the trade-offs between water consumption and carbon uptake. It is also a critical parameter for understanding plant responses to environmental changes. This study introduced an innovative set of WUE-related parameters, including maximum water use efficiency (WUEmax) and associated coefficients of water potential, loss, strategic usage, and total usage (WPC, WLC, WSC, and WTC, respectively) in providing a comprehensive evaluation of water use strategies in 48 common tropical plant species during the natural light fluctuations. These parameters exhibited significant differences among plant types, with sun-adapted and shade-tolerant plants (both C3) showing mean of WUEmax values of 3.81 ± 0.63 and 5.42 ± 1.61 μmol mmol−1, respectively, whereas C4 plants demonstrated a greater WUEmax of 7.04 ± 1.77 μmol mmol−1. Compared to C3 plants, particularly shade-tolerant types, C4 plants exhibited significantly higher WPC and WTC (p < 0.05). Furthermore, shade-tolerant plants displayed lower WLC and higher WSC than sun-adapted plants, suggestive of their specialized adaptations to variations in light intensity. The sensitivity of stomatal and mesophyll conductance (i.e., gs and gm) to incident light (Iinc) and/or intercellular CO2 concentration (Ci) helped clarify the source of variation in WUE-related parameters. In sun-adapted plants, gs was sensitive to changes in both Iinc and Ci. In terms of gm, shade-tolerant plants exhibited the lowest overall sensitivity to Iinc. Increasing atmospheric CO2 concentrations from 400 to 450 ppm caused WUE-related parameters to vary, with this response differing among plant types. These insights emphasize the significance of plant adaptation strategies in tropical rainforest ecosystems.

Cycling of dissolved organic nutrients and indications for nutrient limitations in contrasting Amazon rainforest ecosystems

In the nutrient-poor soils of the Amazon rainforest, phosphorus (P) emerges as a critical limiting factor for ecosystem productivity. Despite these limitations, the Amazon exhibits remarkable productivity that is maintained by its efficient nutrient recycling mechanisms. Central to this process is the role of organic matter, particularly its dissolved (DOM) fraction, which serves as a crucial nutrient reservoir for both plants and microorganisms. This study delves into the dynamics of nutrient-containing DOM within the soils of two contrasting rainforest ecosystems: clayey terra firme forests, known for their robust nutrient recycling and presumed P-limitation, and sandy white-sand forests, characterized by reduced nutrient recycling capacity and presumed nitrogen (N)-limitation. Utilizing ultra-high resolution mass spectrometry (HR-MS), we analyzed the molecular composition of dissolved organic nutrient species. We evidenced nutrient limitation applying innovative concepts: (1) assessing nutrient depletion in DOM via nutrient-to-carbon ratios, (2) comparing the composition of nutrient-enriched DOM pools across soil depth profiles to infer microbial nutrient processing, and (3) examining the temporal variability of nutrient-containing DOM as an indicator of nutrient uptake and production. Our results corroborate the hypothesis of P-limitation in terra firme forests, with significant processing of N-containing DOM also observed, indicating a synergistic demand for both P and N. Surprisingly, white-sand soils exhibited no signs of N-limitation but instead sulfur (S)-limitation, a novel finding for these ecosystems. This study highlights the diversity of potential nutrient limitations in the central Amazon and the importance of the bioavailable “black box” DOM for tropical nutrient cycles.

The Agoutis: A Future Model for Ecologically Relevant Neuroscience and Physiology In Natura

ABSTRACTThe overarching goal of neurobiology is to understand how complex behaviors are generated by the nervous system. The behavior of each species, and the brain that controls it, is shaped by the historical and current state of the environment that they inhabit. This fact is juxtaposed with the reductionist approach of neuroscience that isolates animals from their natural environment. Understanding how brains evolved to orchestrate the myriads of natural behaviors an animal performs in response to its environment requires an integrative approach to neuroscience that considers ecology, ethology, and evolution. Current technological developments are leading us to an inflection point at which studying brain functions in the wild is now possible. Ecological studies on how the environment affects behavior of animals (i.e., hibernation, foraging, food hoarding, and nest building) have framed a plurality of questions to be answered mechanistically, and yet, only few studies have addressed the relationship between the environment and the brain's anatomy and physiology. Neuroscience needs new animal models that allow us to tackle such questions in the wild. Here, we propose a new animal model for wild neuroscience, the agouti (Dasyprocta spp.), a large wild rodent playing a critical seasonal role in the maintenance of the central and south American rainforest ecosystems. We focus on how a rodent model, like the agouti, will allow for the investigation of large‐scale brain dynamics during seasonal behaviors of ecological importance: scatter‐hoarding and retrieval. We describe agouti evolution, ecology, and physiology as well as neuro‐anatomical and neurophysiological studies, which have set the foundation for future neuroscience in natura. We suggest agoutis have the potential to be a groundbreaking model for wild neuroscience.

Modelling and Mapping of Aboveground Carbon of Oluwa Forest Reserve Using LandSat 8 TM and Forest Inventory Data

This research was carried out within the Oluwa Forest Reserve to evaluate and forecast its capacity for aboveground carbon sequestration using data from the Landsat Thematic Mapper. The Oluwa Forest Reserve, situated in Ondo State, Nigeria, is renowned for its abundant biodiversity and vast expanse. Assessing the forest's aboveground biomass and carbon traditionally involves intricate and expensive processes necessitating the expertise of diverse professionals and specialized equipment. Hence, this study investigated the utilization of Geographic Information System (GIS) and Remote Sensing (RS) technology, employing Landsat bands to calculate spectral indices and construct linear models for predicting the aboveground carbon sequestration potential of the tropical rainforest ecosystem within the Oluwa Forest Reserve. The measured aboveground carbon from sample plots, alongside the estimated spectral indices, was utilized to simulate the distribution of aboveground carbon across the Oluwa Forest Reserve. A positive linear correlation was identified between the observed data and the estimated spectral indices. Consequently, linear models were developed, and the most suitable model was determined through statistical analysis. The average aboveground carbon estimated from the sample plots was 150.70 tons per hectare (t/ha), closely aligning with the predicted value of 149.80 t/ha. Statistical analysis yielded a coefficient of determination of 94% and a Root Mean Square Error of 6.38E-16. These results indicate that the selected model accurately predicts the distribution of aboveground carbon within the Oluwa Forest Reserve. This study underscores the importance of spectral data, GIS, and RS in the efficient modelling and mapping of aboveground carbon in extensive forest ecosystems.

Labile Fraction of Organic Carbon in Soils from Natural and Plantation Forests of Tropical China

Labile organic carbon (LOC) is a key driver of forest ecosystem function and may mitigate global climate change through carbon sequestration. To explore the accumulation of LOC in tropical forest soils, we sampled from both planted and natural forests in Hainan Province, the southernmost province of China. We analyzed the concentrations of total organic carbon (TOC) and LOC and characterized various physicochemical properties such as pH and soil texture to understand their inter-relationships in tropical natural and plantation forests. Although the TOC concentration was higher in plantation forests (88.61 g/kg) than in natural forests (68.73 g/kg), the LOC concentration was higher in natural forests (5.12 mg/g) than in plantation forests (4.07 mg/g). Over a depth range of 0–50 cm from the surface, both forest types showed decreasing TOC and LOC concentrations with increasing soil depth, indicating surface aggregation. The soil is slightly acidic and primarily composed of sand particles. Correlation analysis showed a highly significant negative correlation between LOC concentration and soil pH in both forest types (p &lt; 0.01). Soil LOC was positively correlated with soil clay and silt particles and negatively correlated with sand particles. This study provides valuable insights into soil carbon sequestration in tropical rainforest ecosystems in both plantation and natural tropical forests.

COMPOSITION, STRUCTURE, AND CARBON SEQUESTRATION OF DIFFERENT RAINFOREST ECOSYSTEMS IN THE GUNUNG GEDE PANGRANGO NATIONAL PARK, INDONESIA

ARTICLE HIGLIGHTS- High demand for environmental services makes the park vulnerable to human activities.- Both ecosystems are well regenerated; seedling &gt; sapling &gt; pole &gt; tree (inverted J)- Both ecosystems show normal diversity conditions and stable species distribution.- Growth of Maesopsis eminii needs monitoring to preserve forest purity.- Montane forests have greater biomass, carbon stocks, less anthropogenic disturbanceABSTRACTThe Gunung Gede Pangrango National Park (GGPNP) area is one of the vital ecosystems that support the environment in West Java Province, Indonesia. It is a unique area that has multiple forest ecosystems, including lowland rainforest and montane rainforest ecosystems. Despite the GGPNP’s status as a conservation area, the high demand for the GGPNP’s environmental services makes the region vulnerable to disturbances from human activities. Several studies have been conducted in the GGPNP area (lowland and montane forest ecosystems), however, the results of this study are still necessary to explain the forest dynamics and forest carbon sequestration in this location. The objective of this research was to analyze the structure, composition, and carbon sequestration of stands in the lowland and montane rainforest ecosystems in the GGPNP area. Data processing and analyses were conducted using diversity indices, biomass-carbon stock estimation, and carbon dioxide sequestration estimation. The results showed that the GGPNP lowland and montane rainforest ecosystems were well regenerated. The number of seedlings &gt; saplings &gt; poles &gt; trees and the graph showed a reverse “J” pattern. The GGPNP lowland rainforest ecosystem was dominated by Neonauclea lanceolata and had relatively higher species diversity. The GGPNP montane rainforest ecosystem was dominated by Castanopsis acuminatissima with a higher individual density, denser canopy, and more complex canopy strata. The lack of regeneration in several species of trees heightens the threat to these species’ existence in the future. Biomass, carbon stocks, and carbon sequestration in the GGPNP montane rainforest were greater than those in the GGPNP lowland rainforest. The GGPNP montane rainforest ecosystem had older forest stands, a larger average tree diameter, and lower potential for anthropogenic disturbances.

Significance of AI-assisted techniques for epiphyte plant monitoring and identification from drone images

Monitoring forest canopies is vital for ecological studies, particularly for assessing epiphytes in rain forest ecosystems. Traditional methods for studying epiphytes, such as climbing trees and building observation structures, are labor, cost intensive and risky. Unmanned Aerial Vehicles (UAVs) have emerged as a valuable tool in this domain, offering botanists a safer and more cost-effective means to collect data. This study leverages AI-assisted techniques to enhance the identification and mapping of epiphytes using UAV imagery. The primary objective of this research is to evaluate the effectiveness of AI-assisted methods compared to traditional approaches in segmenting/identifying epiphytes from UAV images collected in a reserve forest in Costa Rica. Specifically, the study investigates whether Deep Learning (DL) models can accurately identify epiphytes during complex backgrounds, even with a limited dataset of varying image quality. Systematically, this study compares three traditional image segmentation methods Auto Cluster, Watershed, and Level Set with two DL-based segmentation networks: the UNet and the Vision Transformer-based TransUNet. Results obtained from this study indicate that traditional methods struggle with the complexity of vegetation backgrounds and variability in target characteristics. Epiphyte identification results were quantitatively evaluated using the Jaccard score. Among traditional methods, Watershed scored 0.10, Auto Cluster 0.13, and Level Set failed to identify the target. In contrast, AI-assisted models performed better, with UNet scoring 0.60 and TransUNet 0.65. These results highlight the potential of DL approaches to improve the accuracy and efficiency of epiphyte identification and mapping, advancing ecological research and conservation.

The emission of CO from tropical rainforest soils

Abstract. Soil carbon monoxide (CO) fluxes represent a net balance between biological soil CO uptake and abiotic soil and (senescent) plant CO production. Studies largely from temperate and boreal forests indicate that soils serve as a net sink for CO, but uncertainty remains about the role of tropical rainforest soils to date. Here we report the first direct measurements of soil CO fluxes in a tropical rainforest and compare them with estimates of net ecosystem CO fluxes derived from accumulation of CO at night under stable atmospheric conditions. Furthermore, we used laboratory experiments to demonstrate the importance of temperature on net soil CO fluxes. Net soil surface CO fluxes ranged from −0.19 to 3.36 nmol m−2 s−1, averaging ∼1 nmol CO m−2 s−1. Fluxes varied with season and topographic location, with the highest fluxes measured in the dry season in a seasonally inundated valley. Ecosystem CO fluxes estimated from nocturnal canopy air profiles, which showed CO mixing ratios that consistently decreased with height, ranged between 0.3 and 2.0 nmol CO m−2 s−1. A canopy layer budget method, using the nocturnal increase in CO, estimated similar flux magnitudes (1.1 to 2.3 nmol CO m−2 s−1). In the wet season, a greater valley ecosystem CO production was observed in comparison to measured soil valley CO fluxes, suggesting a contribution of the valley stream to overall CO emissions. Laboratory incubations demonstrated a clear increase in CO production with temperature that was also observed in field fluxes, though high correlations between soil temperature and moisture limit our ability to interpret the field relationship. At a common temperature (25 °C), expected plateau and valley senescent-leaf CO production was small (0.012 and 0.002 nmol CO m−2 s−1) in comparison to expected soil material CO emissions (∼ 0.9 nmol CO m−2 s−1). Based on our field and laboratory observations, we expect that tropical rainforest ecosystems are a net source of CO, with thermal-degradation-induced soil emissions likely being the main contributor to ecosystem CO emissions. Extrapolating our first observation-based tropical rainforest soil emission estimate of ∼ 1 nmol m−2 s−1, global tropical rainforest soil emissions of ∼ 16.0 Tg CO yr−1 are estimated. Nevertheless, total ecosystem CO emissions might be higher, since valley streams and inundated areas might represent local CO emission hot spots. To further improve tropical forest ecosystem CO emission estimates, more in situ tropical forest soil and ecosystem CO flux measurements are essential.

Levels of Potentially Toxic and Essential Elements in Water and Estimation of Human Health Risks in a River Located at the Interface of Brazilian Savanna and Amazon Biomes (Tocantins River).

The Tocantins-Araguaia basin is one of South America's largest river systems, across three Brazilian states (Maranhão, Tocantins, and Pará), within the Legal Amazon region. Despite draining extensive Cerrado savanna and rainforest ecosystems, it has suffered significant degradation, notably in the past 40 years. Human activities, including agricultural expansion, deforestation, and the introduction of non-native species, have worsened the environmental damage, which is alarming since many residents and villages along the middle Tocantins River rely on it for water supply, recreation, and fishing. This study assessed the concentration of potentially toxic and essential elements in water samples from four sampling sites distributed along the middle Tocantins River. The monitoring occurred throughout 2023, involving the measurement of parameters both on-site and in the laboratory. Water quality and its health implications were evaluated using the Weighted Arithmetic Water Quality Index (WAWQI), the Water Quality Index (WQI), and the health risk assessment index. The levels of aluminum, copper, iron, magnesium, and selenium exceeded legal standards. Seasonal fluctuations indicate a complex dynamic influenced by climatic or seasonal factors, with February showing the highest values. Site P1, located in urban areas, exhibited elevated mean concentrations for conductivity, total dissolved solids (TDS), and chlorophyll, indicating the need for continuous monitoring. The nitrogen concentrations at P1 raise concerns regarding drinking water quality, which is a concern for the region's residents who use untreated river water. Despite seasonal variations in element concentrations, the overall WAWQI categorized all sections as "Excellent," and the WQI rated as "Good." Human health risk assessments detected no risks, but continuous monitoring and interventions are crucial for sustained water quality improvement.

An inadequate sampling of the soundscape leads to over-optimistic estimates of recogniser performance: a case study of two sympatric macaw species

ABSTRACT Passive acoustic monitoring (PAM) – autonomously recording ambient sound – could dramatically increase the scale and robustness of species monitoring in rainforest ecosystems. PAM generates large volumes of data that require automated methods of target species detection. Species-specific recognisers, which often use supervised machine learning, can achieve this goal. However, they require a large training dataset of target and non-target signals, which is time-consuming and challenging to create. Unfortunately, very little information about creating training datasets for supervised machine learning recognisers is available, especially for tropical ecosystems. Here, we show an iterative approach to creating a training dataset that improved recogniser precision from 0.12 to 0.55. By sampling background noise using an initial small recogniser, we can address one of the significant challenges of training dataset creation in acoustically diverse environments. Our work demonstrates that recognisers will likely fail in real-world settings unless the training dataset size is large enough and sufficiently representative of the ambient soundscape. We outline a workflow that can provide users with an accessible way to create a species-specific PAM recogniser that addresses these issues for tropical rainforest environments. Our work provides important lessons for PAM practitioners wanting to develop species-specific recognisers for acoustically diverse ecosystems.

Exploring Pliocene Vegetation Variability through Wood Fossil Analysis from Jasinga, Indonesia

Residents of Jasinga, West Java, consistently reported the presence of an abundance of wood fossils. We examined geological settings and wood fossils to investigate the paleovegetation types in the region. This research aims to map the distribution of wood fossils and interpret the paleoenvironment based on paleontological evidence. Lithostratigraphic measurements were performed, followed by a description of wood fossil anatomy in micro-thin section observations, isolation of palynological fossils from the host rock through chemical preparation techniques, and geochemical analysis using X-ray fluorescence spectroscopy. Our findings indicate that the area comprises Pliocene fluvial-volcanoclastic deposits containing several dipterocarp wood fossils, including Parashoreoxylon, Dryobalaonoxylon, Shoreoxylon, Anisopteroxylon, and Dipterocarpoxylon. There were also non-dipterocarp wood fossils from Apocynaceae, Combretaceae, Fabaceae, and Olacaceae. Most wood fossils in these deposits were silicified (SiO2: 92.7 ± 1.88%), preserving the wood tissue structures. Additionally, the wood fossil-rich strata contains fossilized palynomorphs, including pollen fossils from Dipterocarpaceae, Convolvulaceae, and Florschuetzia, and spore fossils from Stenochlaenidites, Verrucatosporites, and Lygodium, indicating the presence of a more diverse paleovegetation. These results support the existence of paleotropical rainforests. Our study suggests that paleoclimatic and paleovolcanic settings have significantly shaped the paleotropical rainforest ecosystems in the southern part of Sundaland during the Early Pliocene.

Modelling and Mapping of Aboveground Carbon of Oluwa Forest Reserve Using LandSat 8 TM and Forest Inventory Data

This study was conducted in Oluwa Forest Reserve to assess and predict its aboveground carbon sequestration potentials using LandSat Thematic Mapper data. The Oluwa Forest Reserve, Ondo State, Nigeria, is recognized for its rich biodiversity and extensive size. To estimate its forest aboveground biomass and carbon should be complex and costly endeavour requiring the expertise of various professionals and equipment. Consequently, this study explored the use of Geographic Information System (GIS) and Remote Sensing (RS) technology using LandSat bands to estimate spectral indices in fitting linear models to predict the aboveground carbon sequestration potentials of the tropical rainforest ecosystem of Oluwa Forest Reserve. The observed aboveground carbon from sample plots and the estimated spectral indices were used to model the spread of aboveground carbon of Oluwa Forest Reserve. Positive linear relationship exists between the observed and the spectral indices data estimated. Therefore, linear models were fitted and the best-fit was determined using statistical measures. The aboveground carbon average estimated from the sample plots and the predicted were 150.70 t/ha and 149.80 t/ha, respectively. The coefficient of determination 94% and Root Mean Square Error = 6.38E-16, respectively were obtained statistically. The chosen model predicts the aboveground carbon spread of Oluwa Forest Reserve adequately. The study revealed that spectral data, GIS and RS are critical for large forest aboveground carbon modelling and mapping for efficiency.

Reptiles and amphibians from the fragments of seasonal Atlantic Forest in northern Paraná, Brazil

Amphibians and reptiles play vital roles within intricate trophic networks as predators, prey, pollinators, and seed dispersers, contributing to nutrient cycling and bioturbation. Tropical regions, characterized by their conducive climates, harbor substantial reptilian and amphibian diversity, highlighting their importance for biodiversity conservation. This study endeavors to bridge knowledge gaps by presenting a comprehensive inventory of amphibian and reptile species within the northern region of the Paraná State, Brazil. Employing active searches and acoustic monitoring, we documented 28 species across diverse microhabitats, reflecting ecological diversity. Analyses of abundance, distribution, and diversity revealed comparable trends between dry and wet seasons. Notably, a broad range of generalist species was observed, adapted to varying ecological niches. Our findings emphasize the relevance of detailed faunal inventories to comprehend and manage biodiversity, particularly in understudied regions, contributing to effective conservation strategies in Seasonal Atlantic Rainforest ecosystems.

Phylogeny, chronology, and phylogeography in Australasian Hypnodendraceae

Abstract The Hypnodendrales form the sister group to all other pleurcarpous mosses in the superorder Hypnanae. Many species are closely associated with the cool temperate rainforests of Australasia, while others are widespread in higher altitude wet forests across tropical South-East Asia. Several of the Malesian entities are taxonomically ambiguous, having been variously treated as species complexes or as single very variable species. Here we use dated phylogenies to examine the timing of diversification of major clades within the Hypnodendrales, test the hypothesis that widespread, taxonomically problematic species have diversified relatively recently in South-East Asia from within clades of southern temperate origin, and address taxonomic questions within Hypnodendron. A chronogram with broad taxonomic sampling is constructed, followed by a second dated phylogeny with dense sampling from Hypnodendron vitiense, a representative morphologically variable species found throughout Eastern Australia and South-East Asia. The crown group Hypnodendrales are found to have originated in the mid-Cretaceous, although they share a Most Recent Common Ancestor (MRCA) with the other Hypnanae in the late Jurassic. Extant members of Hypnodendron share a MRCA ±28 Mya, a little before the start of the collision of Australia with the Sunda plate that initiated the Australasian–Malesian floristic interchange. Within H. vitiense, there is strong phylogenetic structure consistent with the diversification and isolation of populations in South-East Asia within the last 10 Mya. The New Zealand endemic H. marginatum is found to be derived from within an Australasian clade of H. vitiense, this in turn being distinct from a South-East Asian/tropical Australian H. vitiense clade. Our results suggest that the phylogeography of this prominent group of mosses closely mirrors that of the rainforest ecosystems of which they are a part.

Construction of the Ecological Security Pattern in Xishuangbanna Tropical Rainforest Based on Circuit Theory

Urban modernization and economic globalization have led to significant changes in traditional natural landscapes. The unregulated and large-scale expansion of rubber plantations in Xishuangbanna has resulted in water and scenic forests being replaced by rubber forests and the complex rainforest ecosystem being replaced by simple artificial forests. This has resulted in increasingly prominent ecological problems such as soil erosion, regional microclimate changes, and sharp declines in biodiversity. The ecological security pattern is an important way to protect regional ecological sustainability. Taking the tropical rainforest in Xishuangbanna as an example, this study identified ecological sources through the evaluation of the importance of ecosystem services, constructed resistance surfaces through ecological sensitivity evaluation, and used circuit theory to simulate ecological processes in heterogeneous landscapes by calculating “electricity” or “resistance”, thereby identifying ecological corridors and key ecological nodes. The results identified 31 ecological source areas, 65 key ecological corridors, 7 potential ecological corridors, 37 ecological pinch points, and 99 ecological barriers. The overall distribution of ecological sources was scattered, with higher density in the northwest and southeast regions. Ecological corridors were distributed along high mountains, and both ecological sources and corridors were mainly composed of forest land. Based on circuit theory, this study filled the gap in the MCR model’s inability to identify the true width of corridors due to ignoring the randomness of biological migration. It determined the spatial range of ecological corridors and the specific locations of ecological nodes and barriers, providing a reference for solving ecological problems in Xishuangbanna, such as “rainforest fragmentation”.

Phylogenetics, character evolution, and historical biogeography of the Neotropical genus Besleria (Gesneriaceae)

Abstract Besleria, a genus of perennial herbs, shrubs, or small trees growing in the understorey of rainforests, is one of the largest genera of neotropical Gesneriaceae, with over 165 species. Despite the ecological importance and ubiquity of Besleria in rainforest ecosystems, taxonomic and evolutionary studies of Besleria are limited. Here, we generated a phylogenetic analysis of Besleria using four nuclear and chloroplast DNA regions (ITS, matK, rps16, and trnL-trnF) covering more than 50% of the recognized species, along with two secondary calibration points to infer divergence times. Our results support the monophyly of Besleria and allowed us to revise the infrageneric classification and biogeographical history of the genus. We identified five major clades that do not correspond to sections or subsections in previous classifications. These clades are well circumscribed geographically but remain difficult to characterize using previously hypothesized morphological characters. Biogeographical reconstructions indicate an origin in the northern Andes during the Middle Miocene (ca. 15 Mya). The current distribution patterns of this plant group have been significantly shaped by geological and climatic events, particularly Andean uplift and the formation of the Panama Isthmus.

Efficiency of live trapping protocols to assess small mammal diversity in tropical rainforests of Sri Lanka

Live trapping is used extensively for small mammal studies in both temperate and tropical ecosystems. The effectiveness of such studies is dependent on several factors. This paper attempts to investigate how one of these factors, namely the trapping intensity, affects the assessment of species richness and abundance of small mammals in rainforest ecosystems in southwest Sri Lanka. Eight-day live trapping surveys were conducted in seven selected forests yielding a total of 5600 trap days with a total of 186 individuals belonging to nine species being captured. It was evident that, using 100 traps with a trap density of 140 traps per ha, over 90% of the species recorded from each of the seven forests were captured within the initial four days of live trapping after which the rate of capture of new species sharply declined. The results also show that the more common species were captured sooner than the more rare ones. Considering these trends, a four-day trapping protocol could be recommended to broadly compare small mammal communities between forests or habitat types. The number of individuals captured, on the other hand, probably attracted by the bait, increased as trapping progressed; this very likely leads to overestimation of species abundance. Since such projects in developing countries are subject to budgetary constraints, costs incurred are also addressed.

A new species of Guadua (Poaceae: Bambusoideae: Bambuseae: Guaduinae) from the Colombian Amazon

A new species of Guadua, Guadua bambuzoniae Londoño, is described from the Amazon region of Colombia, specifically in the tropical rainforest ecosystem. This species is unusual in that it grows in swampy areas and has several distinct characteristics that differentiate it from all other South American species of Guadua. These include erect and hollow culms at the base, as well as solid and arched culms at the middle and upper portions; primary branches that develop thorns at each culm node; usually a falcated, prominent and fimbriate auricle on the upper part of the culm sheath on one side; elongated and glabrous leaf sheaths; a usually straight, linear-lanceolate pseudospikelet; lemmas pubescent toward the margins with the margins densely ciliated, but otherwise glabrous, and a conspicuous and strong mucron; and paleas only slightly shorter than the lemmas, with broadly winged keels. Here, we provide a geographical distribution map, illustrations, photographs, and a morphological comparison with G. macrospiculata and G. uncinata.