Ecosystem Research Articles

Mechanisms Maintaining Biomass Stability in Woody Species Communities in Evergreen Broadleaved Forests of Dong Nai Culture and Nature Reserve, Dong Nai province, Southern Vietnam

Tropical forest ecosystems experience dynamic changes in response to environmental fluctuations and disturbances. Understanding the mechanisms governing their stability is crucial for maintaining ecosystem services. Among these ecosystems, evergreen broadleaved forests play a pivotal global role. This study investigates the impacts of overyielding, stand structure, species asynchrony, and the stability of dominant species on community biomass stability (CBS) within the Dong Nai Culture and Nature Reserve's evergreen broadleaved forests. The study utilized species richness, diameter-at-breast-height (DBH) variation coefficient, species asynchrony, and stability of dominant species as explanatory variables. The response variables included CBS, mean biomass (µ), and biomass standard deviation (σ). Three structural equation models (SEMs) were constructed to assess the relative strengths of direct and indirect effects among these variables. The results indicated that: (1) The SEMs achieved a good fit, explaining 41.8% of the variance in CBS. (2) Species richness negatively correlated significantly with µ (path coefficient = -0.112) and σ (-0.056). (3) DBH variation coefficient showed significant negative correlations with CBS (-0.161) and µ (-0.087). (4) Species asynchrony exhibited significant positive correlations with CBS (0.061), µ (0.076), and σ (0.061). (5) Dominant species stability showed significant positive correlations with CBS (0.588) and µ (0.153) and a negative correlation with σ (-0.588). These findings underscore that while stand structure and species asynchrony significantly influence CBS in evergreen broadleaved forests, the stability of dominant species emerges as the primary predictor of CBS. Therefore, effective forest management strategies should prioritize conserving and enhancing conditions that support dominant species, ensuring the sustainability of forest ecosystems in the study area.

Insight into the assembly process of angiosperms and arbuscular-mycorrhizal fungi in tropical wetland ecosystems

ABSTRACT Background The interaction between plants and mycorrhizal fungi is one of the most important and well-studied in ecology. However, the manner in which ecological communities of plants and arbuscular mycorrhizal (AM) fungi are structured by both deterministic and stochastic processes remains unclear. Aims To quantify the role of deterministic and stochastic assembly processes in both plant and arbuscular mycorrhizal (AM) fungal communities along with environmental filters in the assembly of communities in areas subject to flooding. Methods We studied phylogenetic relationships and diversity measures in plants and arbuscular mycorrhizal fungi in three tropical coastal wetland communities with contrasting landscapes and soil properties. Results We found that non-random processes were dominant in plant communities, while mycorrhizal communities appeared to be determined by stochastic processes. Clustering trends were predominant in plant communities in areas subject to flooding. Conclusion Environment filters and limiting similarity drive the plant community assembly, whereas ecological drift and/or dispersal limitations were determinants in the assembly of mycorrhizal communities. Environmental filters were found to be the main driver of plant community assembly in in areas subject to flooding.

Unraveling global species richness patterns of the Lysmatidae family: a multi-scale and multi-hypothesis ecological approach

While diversity gradients are well-explored in macroecology, factors shaping species richness at broad scales remain debated. We investigated the species richness of the decapod family Lysmatidae across 4 spatial scales: realm, province, ecoregion, and local (2° × 2° grid cells). We tested 4 ecological hypotheses: physiological stress (PSH), resource availability (RAH), habitat heterogeneity (HHH), and anthropogenic impact (AIH). Occurrence data (52 Lysmatidae species) and environmental variables (salinity, temperature, primary productivity, bathymetry, coral richness, anthropogenic impact index) were obtained from online databases and literature. Fifteen regression models, incorporating spatial filters, were tested to assess the hypotheses. The highest Lysmatidae species richness occurred in the Tropical Atlantic and Central Indo-Pacific realms. Richness varied with scale, with the highest values in the transition between the tropical and subtropical zones. Bathymetry was associated with Lysmatidae richness across all scales, especially at local and ecoregional scales, while coral richness was related to province and realm scales. HHH explained Lysmatidae richness patterns at the realm scale. Variables related to PSH and AIH were associated with richness at the ecoregion and province scales. Our study emphasized the importance of scale in biodiversity research, influencing richness patterns in Lysmatidae, and pointed to bathymetry, coral richness, and temperature range as the main drivers of richness. As this study showed a relationship between Lysmatidae richness, coral richness, and temperature at 3 spatial scales, this family may be susceptible to the effects of climate change, such as tropicalization of subtropical zones and defaunation of tropical ecosystems, including coral reefs.

Early Sri Lankan coastal site tracks technological change and estuarine resource exploitation over the last ca. 25,000 years

The island of Sri Lanka was part of the South Asian mainland for the majority of the past 115,000 years, and connected most recently during the Last Glacial Maximum via the now submerged Palk Strait. The degree to which rising sea levels shaped past human adaptations from the Pleistocene and into the mid to late Holocene in Sri Lanka has remained unclear, in part because the earliest reliable records of human occupation come from the island’s interior, where cave sites have revealed occupation of tropical forest ecosystems extending back to 48 thousand years (ka). The island’s earliest known open-air sites are all much younger in date, with ages beginning at 15 ka and extending across the Holocene. Here we report the earliest well-dated open-air coastal site in Sri Lanka, Pathirajawela, which records human occupation back to ca. 25,000 years ago. We show that humans at Pathirajawela consistently adapted to changing ecosystems linked to sea level transgression and coastal evolution from the Last Glacial Maximum into the Holocene. The presence of anthropogenic shell midden deposits at the site from ca. 4.8 ka, focused almost exclusively on a single taxon, indicates intensification of estuarine resource exploitation, as humans responded to opportunities presented by the formation of new coastal ecosystems.

A gigantic new terror bird (Cariamiformes, Phorusrhacidae) from Middle Miocene tropical environments of La Venta in northern South America

AbstractOur knowledge of the fossil avifauna from the Middle Miocene La Venta locality in Colombia is limited almost entirely to aquatic birds. Phorusrhacidae, popularly known as ‘terror birds’, are a group of highly diversified cursorial birds that played the role of apex predators during most of the Cenozoic. Here we present the first record of a phorusrhacid from the La Venta locality. This terror bird can be assigned to the ‘Phorusrhacinae’, a subfamily for which the monophyly is under debate. The fragment of left distal tibiotarsus represents the most northern record of this group for South America and may correspond to the largest terror bird that ever existed. This suggests that terror birds might also have inhabited more tropical ecosystems, providing evidence that they were apex predators in tropical palaeocommunities. Additionally, our research contributes to an understanding of the biogeographical patterns of the Phorusrhacidae lineage dispersal into northern South America and subsequent colonization of North America.

Heavy metal dynamics in riverine mangrove systems: A case study on content, migration, and enrichment in surface sediments, pore water, and plants in Zhanjiang, China

Mangroves serve a crucial role as metal accumulators in tropical and subtropical marine ecosystems, particularly in riverine mangroves, which frequently interact with terrestrial sources. In this study, we focused on the Gaoqiao and Jiuzhou Rivers within the Zhanjiang mangrove forest in Guangdong, China, and collected leaves and surface sediments from the dominant mangrove plant, Aegiceras corniculatum, near the riverbanks. We focused on seven heavy metals (Cr, Cu, Zn, As, Cd, Pb, and Hg) in mangrove leaves, surface sediments, and pore water due to their environmental significance and frequent occurrence in mangrove ecosystems. We employed multivariate statistical methods and pollution indicators to assess the potential sources and risk levels of heavy metals in these sediments. Our results reveal that the concentrations of the seven heavy metals in the sediments of the Gaoqiao and Jiuzhou Rivers varied significantly, ranging from 0.03 mg/kg to 100.00 mg/kg. Cd posed the highest ecological risk, followed by Hg and As. The comprehensive potential ecological risk in the Gaoqiao River was lower than that in the Jiuzhou River, likely due to the distribution of industrial enterprises (such as printing and cement plants) in the upper reaches of the Jiuzhou River. Additionally, the heavy metal content in the leaves and pore water of A. corniculatum ranged from 0.01 to 51.58 mg/kg and 0.001 to 133.70 μg/L, respectively. There was a significant correlation between the heavy metal concentrations in the leaves and the pore water of A. corniculatum. Notably, the leaves of A. corniculatum exhibited a remarkable Hg-enrichment capability, highlighting its potential as a mercury accumulator. Most heavy metals in A. corniculatum leaves, pore water, and sediment were concentrated in the middle and upper reaches of the river, primarily due to anthropogenic terrestrial inputs from residential production activities upstream. Consequently, heavy metal pollution in riverine mangroves is primarily associated with human activities such as aquaculture, agricultural planting, and industrial production.

The Beehives of Stingless Bees in Manipur, India and Their Ecological and Economic Impact to Farmers

Stingless bees (Trigona spp.) are important pollinators in tropical and subtropical ecosystems, playing a vital role in maintaining biodiversity and agricultural productivity. In Manipur, traditional bamboo beehives are used to house these bees, reflecting a culturally significant and sustainable approach to beekeeping. This study examines the ecological and economic impacts of stingless bee beekeeping with bamboo hives in Manipur, using data from field surveys, interviews, and honey production analysis. The results show that stingless bees contribute to a 25-30% increase in crop yield through enhanced pollination. Bamboo beekeeping also generates an average household income increase of 20-35% from the sale of honey and other products. The demand of stingless bee honey is becoming high due to its unique medicinal properties. Despite these benefits, challenges such as habitat loss, climate change, and technical limitations persist. The findings suggest that integrating traditional knowledge with modern beekeeping practices could address these challenges and optimize the ecological and economic potential of stingless bee conservation in the region. This paper emphasizes for supportive policies and further research to fully realize the potential of bamboo beekeeping in Manipur.

Entrega nocturna: Primer registro de polinios de orquídea (Orchidales: Orchidaceae) en polillas prominentes (Lepidoptera: Notodontidae)

Moths are significant pollinators and flower visitors globally, however their roles and mutualistic relationships with plants remain underexplored. This study highlights the novelty of the Nystaleinae Nycterotis jacobensis (Thiaucourt, 2008) as a potential orchid pollinator, evidenced by pollinia found on its proboscis. The specimen, collected in Utría National Natural Park, Colombia, would represent the first report of a prominent moth visiting orchids in this region. Additionally, we review recent observations of Dioptinae moths feeding on flowers, suggesting their potential role as pollinators. Our findings underscore the need for further research on the biology and ecology of Neotropical moths, particularly in ecosystems vulnerable to climate change. Future studies should focus on identifying the specific orchid species visited by Nycterotis and other Nystaleinae, as well as implementing diverse methodologies to assess the impact of these nocturnal pollinators on tropical ecosystem dynamics and their response to environmental changes.

Harnessing Nature's Potential: Innovating Antibacterial Cream through Garlic and Clove Extracts

The onset of the antibiotics period was characterised by the clinical implementation of penicillin, the inaugural antibiotic, unearthed in 1928 by Alexander Fleming in the green mould Penicillium notatum. Garlic and clove have long been used as traditional treatments for different diseases, including infections. Their antibacterial qualities have been attributed to their sulfur-containing components, such as allicin and ajoene in garlic, and eugenol and isoeugenol in clove. In this study, we wanted to produce a novel antibacterial cream leveraging the synergistic properties of garlic and clove extracts. The cream was manufactured utilizing a simple and scalable technique, and its antimicrobial activity was assessed against a panel of microbes present in our surrounding. The results indicated that the cream had considerable antibacterial action against all tested microorganisms, with minimum inhibitory concentrations (MICs) comparable to conventional antibiotics. This study establishes a groundbreaking, ecologically-oriented method for safeguarding and healing the skin. The tropical antimicrobial cream provides a secure and efficient substitute for traditional antimicrobials that may have harsh effects, while also including the nourishing and rejuvenating qualities of tropical botanicals. This groundbreaking research marks a significant advancement in the realm of natural, holistic skin health solutions. The tropical antimicrobial cream stands as a potent alternative to conventional, potentially harsh antimicrobials, offering a safe and effective way to combat skin infections and irritations. Furthermore, its incorporation of nourishing and restorative tropical botanicals transcends mere protection, promoting overall skin health and well-being. Beyond the individual benefits, this innovation holds immense potential for promoting sustainable practices within tropical ecosystems by leveraging resources responsibly and ethically. This paves the way for a future where nature's wisdom empowers us to safeguard our skin with gentle effectiveness, while simultaneously cherishing and preserving the biodiversity that holds the key to our well-being.

Relationships between abiotic factors, foliage chemistry and herbivory in a tropical montane ecosystem.

Herbivore-plant interactions are fundamental processes shaping ecosystems, yet their study is challenged by their complex connections within broader ecosystem processes, requiring a nuanced understanding of ecosystem dynamics. This study investigated the relationship between nutrient availability and insect herbivory in the Australian Wet Tropics. Our objectives were threefold. Firstly, to understand what factors influence nutrient availability for plants and herbivores across the landscape; secondly, to investigate how trees of different species respond to nutrient availability; and thirdly, to unravel how the relationships between resources and plant chemistry affect herbivory. We established a network of 25 study sites covering important abiotic gradients, including temperature, precipitation, and geology. Employing a hierarchical modelling approach, we assessed the influence of climate and geology on resource availability for plants, primarily in the form of soil nutrients. Then, we explored the influence of the above factors on the interaction between herbivory and foliage chemistry across three widespread rainforest tree species, comparing how these relationships emerged across genera. Our findings suggest an overarching influence of climate and geology over soil chemistry, foliar nitrogen, and insect herbivory, both directly and indirectly. However, individual constituents of soil fertility showed equivocal influences on spatial patterns of foliage chemistry once site geological origin was accounted for, suggesting a questionable relationship between individualsoil nutrients and foliar composition. We have demonstrated that herbivore-plant interactions are complex dynamics regulated by an intricate web of relationships spanning different biogeochemical processes. While our results provide some support to the notion that herbivory is affected by resource availability, different species growing under the same conditions can show differing responses to the same resources, highlighting the importance of identifying specific limiting factors rather than simpler proxies of resource availability.

Effects of Harvest Time and Acacia crassicarpa Age on the Physicochemical Characteristics of Apis mellifera L. Honey in Tropical Indonesian Forests

The comprehensive understanding of the physicochemical profile of monofloral honey derived from Acacia crassicarpa, specifically in the Indonesian tropical forest ecosystem, has not been fully explored. The physicochemical characteristics of honey significantly influence its quality and consumer acceptance. Harvest time and the age of Acacia plants, which are suspected to affect honey’s physicochemical properties, are this study’s focal points. Our objective is to analyze the impact of harvest time and Acacia age on the physicochemical characteristics of honey. Using a complete randomized block design, treatments were administered at 14, 21, and 30 days of harvest within three Acacia age groups: 3, 8, and 18 months. The honey composition was assessed following the Indonesian National Standard 8664:2018 procedure. The statistical analysis determined the optimal harvest period for honey by assessing its physicochemical properties and comparing them to the Indonesian National Standard 8664:2018 procedure (SNI 8664:2018 standards). One-way analysis of variance evaluated the effects of harvest time and plant age on composition, followed by a least significant difference tests to identify significant differences between harvest times. Results indicate a significant influence of harvest time and Acacia age on all honey composition variables, including diastase enzyme activity, hydroxymethylfurfural content, moisture level, sugar content, and acidity (P<0.01). Our findings suggest optimal honey harvest at 30 days, aligning with the 8th and 18th months of A. crassicarpa. Most variables met SNI 8664:2018 standards, except acidity levels. Further investigation is needed to discern the causes of acidity in Apis mellifera honey from Indonesian peat swamp forests.

Somatic mutation rates scale with time not growth rate in long-lived tropical trees

The rates of appearance of new mutations play a central role in evolution. However, mutational processes in natural environments and their relationship with growth rates are largely unknown, particular in tropical ecosystems with high biodiversity. Here, we examined the somatic mutation landscapes of two tropical trees, Shorea laevis (slow-growing) and S. leprosula (fast-growing), in central Borneo, Indonesia. Using newly constructed genomes, we identified a greater number of somatic mutations in tropical trees than in temperate trees. In both species, we observed a linear increase in the number of somatic mutations with physical distance between branches. However, we found that the rate of somatic mutation accumulation per meter of growth was 3.7-fold higher in S. laevis than in S. leprosula. This difference in the somatic mutation rate was scaled with the slower growth rate of S. laevis compared to S. leprosula, resulting in a constant somatic mutation rate per year between the two species. We also found that somatic mutations are neutral within an individual, but those mutations transmitted to the next generation are subject to purifying selection. These findings suggest that somatic mutations accumulate with absolute time and older trees have a greater contribution towards generating genetic variation.

Somatic mutation rates scale with time not growth rate in long-lived tropical trees.

The rates of appearance of new mutations play a central role in evolution. However, mutational processes in natural environments and their relationship with growth rates are largely unknown, particular in tropical ecosystems with high biodiversity. Here, we examined the somatic mutation landscapes of two tropical trees, Shorea laevis (slow-growing) and S. leprosula (fast-growing), in central Borneo, Indonesia. Using newly constructed genomes, we identified a greater number of somatic mutations in tropical trees than in temperate trees. In both species, we observed a linear increase in the number of somatic mutations with physical distance between branches. However, we found that the rate of somatic mutation accumulation per meter of growth was 3.7-fold higher in S. laevis than in S. leprosula. This difference in the somatic mutation rate was scaled with the slower growth rate of S. laevis compared to S. leprosula, resulting in a constant somatic mutation rate per year between the two species. We also found that somatic mutations are neutral within an individual, but those mutations transmitted to the next generation are subject to purifying selection. These findings suggest that somatic mutations accumulate with absolute time and older trees have a greater contribution towards generating genetic variation.

Persistence and Dissipation Kinetics of Flubendiamide in the Tropical Sugarcane Ecosystem

Persistence and Dissipation Kinetics of Flubendiamide in the Tropical Sugarcane Ecosystem

The contributions of rainfall and fog to leaf water of tree and epiphyte communities in a tropical cloud forest.

Tropical cloud forest ecosystems are expected to face reduced water inputs due to climatic changes. Here, we study the ecophysiological responses of trees and epiphytes within in an Asian cloud forest to investigate the contributions of rainfall, fog, and soil to leaf water in 60 tree and 30 vascular epiphyte species. We measured multiple functional traits, and δ2H, and δ18O isotope ratios for leaf water, soil water, rainfall, and fog in the wettest (July) and driest (February) months. Using a Bayesian stable isotope mixing model, we quantified the relative contributions of soil water, fog, and rainfall to leaf water. Rainfall contributes almost all the leaf water of the epiphytes in July, whereas fog is the major source in February. Epiphytes cannot tap xylem water from host trees, and hence depended on fog water when rainfall was low. Most of leaf water was absorbed from soil water in July, while fog was an important source for leaf water in February despite the soil moisture content value was high. In February, lower temperatures, along with reduced photosynthesis and transpiration rates, likely contributed to decreased soil water uptake, while maintaining higher soil moisture levels despite the limited rainfall. These contrasting contributions of different water sources to leaf water under low and high rainfall and for different plant groups outline the community-level ecophysiological responses to changes in rainfall. While direct measurements of water flux, particularly in roots and stems, are needed, our results provide valuable insights on tropical cloud forest hydrology under scenarios of decreased fog immersion due to climatic changes.

Non‐native invasive plants in tropical dry forests: a global review of presence, impacts, and management

Tropical dry forests (TDF) are among the most‐threatened terrestrial ecosystems, experiencing ongoing conversion to agricultural fields, pasture, and human settlements. Human disturbances are often precursors to invasion of ecosystems by non‐native species, but research on invasion patterns in tropical ecosystems is sparse, and there is no comprehensive synthesis of invasive species in TDF. We conducted a review of published scientific literature to catalog and synthesize information about invasion by non‐native plants in TDF ecosystems across the globe, drawing out patterns in the invasion of these ecosystems. We found that 130 invasive plant species were documented as present in TDF, but only 25 of these species were mentioned in three or more articles. Almost all 25 of these more‐studied invasive species—mostly pasture grasses, woody legumes, and climbers—have been intentionally cultivated for agricultural or ornamental purposes. Many of these plants are native to open‐canopy savanna or forest edge habitats and benefit from human‐altered disturbance regimes (burning, grazing, and fuelwood and timber harvesting) of TDF fragments within agricultural landscapes. Field studies show that management approaches incorporating invasive removal, native plantings, and reduction in agricultural disturbance (e.g. ungulate fencing and fire control) simultaneously are often the most successful at reducing invasive plant cover. However, management studies in TDF have focused on a limited number of invasive species, and most were conducted in India and Hawaii. Global differences in TDF soils, natural fire regimes, and historic and current land use by humans influence modern biogeographic patterns of invasion and the feasibility of restoration options.

Multiple negative impacts of marine plastic pollution on tropical coastal ecosystem services, and human health and well-being

There is limited empirical evidence showing the impacts of marine plastic pollution on ecosystem services or on human health and well-being in Global South countries. We aimed to estimate these impacts in the tropical archipelago of Indonesia, one of the top emitters of marine plastics globally, through an iterative Delphi survey, with an expert panel (n = 42) consisting of equal numbers of Indonesian scientists, policymakers, and practitioners. After two rounds of the survey, the analysis of interquartile ranges indicated that the experts reached a consensus in their predictions. The experts agreed that, over the next 10 years, plastics would be mainly accumulated in the coastal area of Java, the most densely populated island, and mostly in mangrove ecosystems. While all ecosystem services were harmed by plastic pollution, the most vulnerable services were food provisioning, genetic materials, nursery habitat, and recreation supplied by the highly vulnerable coastal ecosystems of, in descending order, mangrove, coral reef, seagrass, and sandy beach. These impacts on ecosystem services influenced different dimensions of human health and well-being and were dependent on the ecosystem types, as indicated in several statistically significant positive correlations (Spearman's rank), including those between the decline of mangrove ecosystem services and reduced household income, and between the decrease of coral reef ecosystem services and both deteriorating mental health and reduced household income. Overall, this study provides the first indication of Indonesian coastal ecosystems and ecosystem services to be prioritized for mitigation and monitoring efforts. The focus on impacts on human health and well-being also incentivizes ongoing efforts by policymakers, industry and commerce, the third sector, and the public in the country to address the contribution to global marine plastic pollution.

Feathers, folklore, and eco-literacy: Stories ascribe cultural keystone status to avian scavengers in South Asian cities

Abstract We examined the cultural significance of commensal avian scavenger species—vultures, kites, and crows—and their exploitation of anthropogenic resources and sentiments within Delhi’s urban landscapes. For this, we investigated the intrinsic values attributed to these birds by people, which are indicative of complex, rapidly urbanizing social-ecological systems. Semi-structured interviews revealed folk perceptions intertwined with socio-cultural narratives and traditions, shaped by observations of avian morphology, ecology, and behavior. Birds’ nesting habits, habitats, home ranges, and foraging behaviors affected people’s perceptions, while ecosystem services inspired zoomorphism and anthropomorphism via vernacular-nomenclature (e.g., chidiya collectively for songbirds, giddha for scavenging raptors). Culturally rooted perceptions, which informed ritual feeding practices and shaped prevalent attitudes towards commensal species, fostered mutual tolerance, and brought people into closer contact with urban biodiversity. Such physical and cultural proximity is a defining characteristic distinguishing tropical urban ecosystems from their Western counterparts. We also uncovered the web of social-technological influences on animal-related folk stories. The urbanization of perceptions in vulture extinction zones revealed shifts in social-ecological relationships with wildlife. It adds cultural dimensions to the currently appreciated keystone status of vultures, vital for their erstwhile coexistence at extremely high densities in South Asia. Urban transformations, technological advancements, and media exposure potentially reshaped human–animal interface, with media misinformation affecting personalized ecologies. Conflicts and health concerns arose from media narratives on garbage-consuming animals. Our findings offer insights to prevent severing of people and nature connections due to urbanization (e.g., technological applications can integrate scientific knowledge with biocultural narratives and folklore), promoting a new-age eco-literacy.

Vegetative traits, floral biology, and mutualistic interactions in the tropical mountain shrub Ribes ciliatum (Grossulariaceae)

Plant species in tropical mountain ecosystems experience significant environmental variation across short spatial distances. These systems offer an opportunity to assess geographic variation in plant traits in relation to biotic and abiotic environments. We examined plant vegetative and reproductive traits in the shrub R. ciliatum across two native conifer forests in central Mexico. We measured plant height, number of branches, leaf size, flower production, floral morphology, floral longevity, and plant reproductive success in R. ciliatum populations found in fir forests (3100 m) and Hartweg's pine forests (subalpine habitat, 3700 m). We also quantified the level of pollinator dependence, pollinator visitation rates, and fruit consumption rates by frugivorous birds in both populations. Plants were shorter and had smaller leaves in the subalpine forest than in the fir forest. Floral longevity decreased in the subalpine forest, but flower production, flower size, and fruit weight remained similar across populations. Fruit set and pollinator visitation rates were higher in the subalpine forest; however, seed weight and fruit consumption rates did not differ between sites. Hummingbirds and bumblebees were the primary pollinators of R. ciliatum, and the bird Ptiliogonys cinereus was the most important fruit consumer at both sites. Fruit set was entirely dependent on pollinators. Reduced plant size in the subalpine forest coincides with a general pattern associated with high mountain environments. In contrast, reproductive characters had a closer relationship to the pollination environment. The absence of variation in flower size and shape was consistent with the similarity in the composition of the pollinator community. Meanwhile, compared to lower-elevation forests, the subalpine forest exhibited shorter-lived flowers and increased fruit set, associated with higher pollinator visitation rates. Ribes ciliatum is a key resource for pollinators and frugivores at a time of year when few other floral resources are available in these high-elevation mountain forests.

Assessing ecological risks and microplastic pollution in a tropical coastal ecosystem: Effects of rainfall variability in Southeast India

Microplastic pollution poses a significant threat to coastal ecosystems, prompting an in-depth investigation into its seasonal fluctuations and ecological impacts. This study examines microplastics in Cuddalore’s coastal waters and sediments across four seasons. Results show varying microplastic concentrations, peaking during the monsoon and pre-monsoon seasons, likely influenced by rainfall variability. Fibers dominate in both water (69–100 %) and sediment samples (66–92 %), with polyethylene and polyethylene terephthalate as the predominant polymer types in water. Sediments exhibit a more diverse polymer distribution, with polypropylene and polyethylene terephthalate being prevalent. Elevated polymer hazard index and potential ecological risk index raise concerns, reaching values of 108930 and 1125, respectively. This underscores the urgency of implementing effective management strategies to safeguard tropical coastal ecosystems from microplastic pollution. This study highlights the complex interplay between seasonal dynamics, rainfall variability, polymer types, and pollution levels, emphasizing the need for proactive environmental management measures.