Tropical Rainforest Research Articles

Diversity and Baits Preference of Flower Flies (Diptera: Syrphidae) Collected Using Van Someren-Rydon Traps in the Colombian Andean-Amazon Piedmont During Two Rainy Seasons.

Thirty percent of the flower flies (Diptera: Syrphidae) diversity is concentrated in the Neotropics, with few studies in the Amazonian rainforests. We evaluated diversity, phenology and bait preference of syrphids in three lowland habitats (FE = Forest Edge, DSF = Dense Secondary Forest and AFS = Agroforestry System) in La Avispa Nature and Ecotourism Reserve in Caquetá, Colombia, during two rainy seasons (high rainfall intensity, HIR and low rainfall intensity, LIR). Adults were collected using Van Someren-Rydon traps (VSRTs) baited with fermented fruit, decomposed shrimp or decomposed fish. We estimated alpha and beta diversity components within and between habitats. Phenology was compared between rainy seasons. A total of 1,379 syrphids specimens were collected, belonging to 59 species (13 genera). DSF had the highest abundance and richness (n = 812; 43 species). Syrphid abundance was 8.9 times higher (n = 1.240) during HIR, while richness was 1.8 times higher (68 species) than LIR. Copestylum was the most abundant and diverse genus (n = 1,225; 88.8% of all specimens collected). The VSRTs showed high sampling completeness (≥ 90%), suggesting that this methodology is useful and effective for rapid Syrphids inventories. Species replacement was the dominant component of beta diversity, indicating that each habitat contributes with unique species, providing functions for sustainability and ecosystem balance, where connectivity is essential to ensure the provision of ecosystem services in undergoing ecological restoration areas, such as the tropical rainforest studied here.

The quality of alder raw material from stands growing in different habitats

In the present study, an attempt was made to determine the quality of alder raw material growing in different habitat types of forest. The research work was conducted in the Włoszczowa Forest District in Poland. Measurements were taken in 8 stands growing on three forest site types: alder moist forest, alder-ash moist forest, moist forest. In the selected stands, 4-are sample plots were established. In each circular sample plot, DBH and height of all trees in the plot were measured. In the selected trees, the quality of the wood and the type of defects that influenced the wood classification result were determined in the trunk butt end (at a length of 4 metres). In every other plot, a core was taken from a height of 1.3 m in a randomly selected tree to determine the presence of latent defects. The black alder tested on each site achieved very good technical quality. The volume share was dominated by veneer wood, the most of which was estimated in moist forest. Very small amounts were found of lower quality classes. It was found that in less humid habitats than typical alder forests, black alder produces better quality wood. However, once the borings were taken into account, the proportion of each quality class changed dramatically. Hard rot and soft rot degraded the best quality classes to lower quality classes. The share of the best quality wood fell from 60% to 7.57%, while the share of the worst quality wood increased from 5.94% to 40.57%.

Comparison between tropical legumes and natural grasses in improving tropical rainforest soil health: a case study in guava (Psidium Guajava L.) orchards

Tropical rainforest soils, or latosols, are distinguished by their low pH and low fertility. In orchards, co-cultivating grass has become popular as a way to improve soil quality and boost fruit production. Nevertheless, insufficient information is currently available about the response of soil microbial communities in tropical rainforest orchards to grass co-cultivation. Therefore, the present research investigates the effect of grass cultivation on the soil properties and microbial diversity of guava (Psidium guajava L. cv Pearl) latosol orchards. Two varieties of the tropical legume grass Stylosanthes guianensis, i.e., Reyan No. 2 and Ubon, were studied, besides the control (CK), which is without any grass, and the natural grasses treatment (N). The study contained four treatments, i.e., S. guianensis cv. Reyan No. 2, S. guianensis cv. Ubon, CK, and N. Soil samples from the top layer (0–20 cm) and subsoil layer (20–40 cm) were collected to follow the changes in soil microbial biodiversity based on 16 S rDNA analysis. A total of 17,231 kinds of OTUs (Operational Taxonomic Units) were obtained, including 17,165 kinds of bacteria and 66 kinds of Archaea. S. guianensis cv. The Ubon variety, natural grasses, and CK treatments significantly increased the soil microbial richness and evenness in the topsoil layer compared to Reyan No. 2 variety. The β-diversity of soil microbial community was significantly reduced in the natural grasses and Ubon variety treatments at the topsoil layer compared to CK treatment. In the subsoil layer, natural grasses, Reyan No. 2, and Ubon treatments significantly increased the soil microbial community based on β-diversity. The presence of natural grasses caused 49% and 42% increases in the SOC in the top and subsoil layers, respectively, as well as remarkable increases in the available and total soil nitrogen. The grass intercropping enhanced the levels of soil carbon and nitrogen and altered the nature of the soil’s microbial community. The diversity of soil microorganisms in the subsoil layer is significantly altered by the shallow root systems of tropical legume and natural grasses, which have most of their roots concentrated in the top soil layer. Overall, growing grass in tropical orchards benefits the latosolic soil microorganisms, which has enhanced the theoretical underpinnings for using grass to improve the soil quality in latosols orchards.

Potential in Palaeoecological Reconstruction from Modern Pollen Calibrations along the Kukrail Reserve Forest, Central Ganga Plain, India

Deciphering past vegetation composition can be upgraded by examining modern pollen rain and extant vegetation. Here, we compare pollen dataset of 15 surface soil samples from the forested area and open-land and crop-land areas of the Kukrail Reserve Forest, to understand the association between the modern pollen dispersal and the vegetation cover in the Central Ganga Plain. The palynoassemblage recovered from the surface soil displays the tropical moist and dry deciduous woodland comprising Syzygium, Butea, Holoptelea, Terminalia, Emblica , Sapotaceae and Meliaceae indicating warm and humid climate in response to rainfall heterogeneity in the study site. Extensive pollen morphological studies have also been conducted on 15 selected plant taxa for generating the modern pollen flora from this region, which could aid in the accurate identification of fossil pollen. It has been observed that a significant correlation can be seen between the local herbaceous vegetation and pollen data. The excessive incidence of anthropogenic marker pollen (cereal, average value: 17.26%) alongside with cultural pollen taxa like Brassica, Coriandrum and Solanaceae demarcate agricultural impact around the region. The multivariate statistical analysis like box-plot and principal component analysis signifies a sizable dissimilitude and similarity in pollen spectra from different depositional sites. Careful interpretation of past vegetation extent using fossil pollen assemblages is required, especially when the vegetation is treeless (open-land and crop-land areas) due to the fact that a large potential of pollen-source region and subsequently a higher percentage of long-distance anemophilous pollen have been recorded. Therefore, this study has been initiated to analyse recent pollen dispersal and preservation in various depositional settings of tropical reserve forest. Moreover, the account on cultural and anthropogenic pollen indicator could provide valuable insights into the extent of agricultural practices and the degradation of pristine forests and surrounding areas. Thus, the present pollen data would aid in accurately understanding the palaeoecological changes in the tropical forests and surrounding regions of Central Ganga Plain.

Research Progress of Rubber Forest Ecological Restoration Based on CiteSpace

Currently, more and more attention is being paid to ecological restoration, and research on ecological restoration of rubber forests is also developing. In this paper, using CiteSpace 6.3.R1 software and bibliometric analysis, the literature in the field of ecological restoration of rubber forests is visualized and analyzed to support the development of ecological restoration of rubber forests and provide guidance for further research. The results show that the most important research priorities and trends in the field of ecological restoration of rubber forests are currently:(1) Community structure and biodiversity of rubber forests and their influencing factors. Particular attention is paid to the diversity of understorey plants and microbial diversity in the soil. (2) Effects of the conversion of tropical rainforests into rubber forests. Particular attention will be paid to the impact on soil physicochemical properties, ecosystem functions, carbon stocks, biomass, etc. (3) Sustainable management of rubber forests: Special attention will be given to agroforestry rubber forests and the role of semi-natural management practices in the restoration of rubber forests. Future research should continue to promote breeding programs, further explore agroforestry rubber systems and improve management programs for rubber plantations, evaluate and implement ecological restoration projects, and integrate research on climate change and ecological restoration of rubber forests.

Assessing the effects of landscape attributes in medium and large terrestrial mammal richness inside a tropical rainforest biosphere reserve.

The landscape's structure significantly impacts how communities assemble due to the environment filtering and the limitation of dispersal processes. Human activities can enhance or alter these factors, resulting in changing environments and isolated animal populations. In studying this, we used 39 camera trap stations during 102 continuous days in preserved and disturbed areas to assess medium and large terrestrial mammals in the Selva El Ocote Biosphere Reserve in Chiapas, Mexico (REBISO). We identified various groups of mammals and the factors influencing their presence and distribution through VIF, Clustering, RDA, NDMS, ANOSIM multivariate, and niche decomposition (OMI) analyses. The redundancy analysis (RDA) indicated that the most significant variables were altitude, distance to main roads and settlements, and forest cover. The optimal multivariate indicator (OMI) analysis accounted for 88.75% of the variability in niche structure. It revealed that Puma concolor exhibited the highest level of specialization (marginality = 2.96), while Nasua narica displayed the most generalist behavior (marginality = 0.26). Natural elements and human impact played a crucial role in the species' distribution, resulting in patterns in two distinct conditions: one characterized by preserved natural environments and the other affected by significant human impact. Notably, 63% of the species were common in both regions. For instance, Cuniculus paca positively correlated with distance to main roads and altitude, whereas Leopardus pardalis negatively responded to proximity to settlements. This study emphasizes the importance of maintaining habitat connectivity to preserve terrestrial mammal species.

Land‐use changes impact root–fungal network connectivity in a global biodiversity hotspot

Abstract Cross‐kingdom associations play a fundamental role in ecological processes. Yet our understanding of plant–fungal co‐occurrences in tropical rainforests and the potential impacts of land‐use change shaping species connections remain limited. By using amplicon sequencing on DNA from roots and their associated fungal communities, we aim to understand the impact of rainforest transformation on the composition and structure of root–fungal ecological networks in human‐modified landscapes in Sumatra, Indonesia. Each land‐use type supports a distinctive set of indicator species, which are organisms that reflect specific environmental conditions and can signal changes in ecosystem health. We observed a decline in the richness of indicator plant taxa and plant–fungal associations with increasing land‐use intensification. Additionally, there is a turnover in root communities, shifting from native and endemic species in rainforests to non‐native, generalist herbaceous species in rubber and oil palm plantations. Plant–fungal connectivity significantly declined with increasing land‐use intensification, suggesting that managed ecosystems may have weakened root‐fungal interactions. Network analysis highlights the distinct responses of various fungal groups. For instance, arbuscular mycorrhizal fungi (AMF) showed fewer connections with modules linked to oil palm and rubber roots, indicating weakened root–fungal associations in monocultures. This aligns with the observed reduction in AMF diversity in converted land‐use areas compared to forests, further reinforcing the negative impact of land‐use practices in oil palm and rubber monocultures on AMF diversity. Synthesis. Dimensioning the impacts of rainforest transformations below‐ground is constrained by our understanding of fungal functional guilds. Highly modified systems exhibited fewer connections, suggesting a dynamic restructuring of root–fungal relationships in response to land‐use changes. Understanding the intricate interplay between plants and fungi in the face of land‐use change can provide valuable information for conservation efforts, agricultural practices, and ecosystem management strategies aimed at promoting biodiversity, soil health and ecosystem resilience in the context of changing environmental conditions. Moreover, it underscores the importance of communities' networks in land‐use planning and management decisions to support plant and fungal diversity in terrestrial ecosystems.

Island geography drives evolution of rattan palms in tropical Asian rainforests.

Distributed across two continents and thousands of islands, the Asian tropics are among the most species-rich areas on Earth. The origins of this diversity, however, remain poorly understood. Here, we reveal and classify contributions of individual tropical Asian regions to their overall diversity by leveraging species-level phylogenomic data and new fossils from the most species-rich Asian palm lineage, the rattans and relatives (Arecaceae, Calamoideae). Radiators (Borneo) generate and distribute diversity, incubators (Indochina, New Guinea, and Sulawesi) produce diversity in isolation, corridors (Java, Maluku, Sumatra, and the Thai-Malay Peninsula) connect neighboring regions, and accumulators (Australia, India, Palawan, and the Philippines) acquire diversity generated elsewhere. These contrasting contributions can be explained by differences in region size and isolation, elucidating how the unique island-dominated geography of the Asian tropics drives their outstanding biodiversity.

Dayak Benawan Indigenous Futures: Tropical Rainforest Knowledge in Kalimantan, Indonesia

This article examines the cosmology of the Indigenous Dayak Benawan people in the tropical rainforests of West Kalimantan, Indonesia, as an alternative framework for negotiating the future. Through an Indigenous ethnographic approach, this research examines how Dayak Benawan cosmological knowledge, deeply rooted in a spiritual connection with nature, serves as a guiding system for navigating social and ecological changes. Rapid development has significantly transformed our way of life, traditions, and ecological landscape. For the Dayak Benawan community, the forest is not merely a source of material sustenance but a spiritual entity that must be respected and protected. This study specifically investigates the local knowledge embedded in Dayak Benawan rituals, which carry symbolic meanings related to maintaining cosmic balance. These practices reflect the community’s efforts to sustain harmony between humans, nature, and ancestral spirits while functioning as a mechanism for ecological sustainability and development (SDGs), and futurity.

Modelling tree volume for a tropical rainforest in Okomu National Park, Edo State, Nigeria

Modelling tree volume for a tropical rainforest in Okomu National Park, Edo State, Nigeria

Temporal-spatial variation of regulating ecosystem services and analysis of driving factors in Hainan Tropical Rainforest National Park, China

Temporal-spatial variation of regulating ecosystem services and analysis of driving factors in Hainan Tropical Rainforest National Park, China

Palynological analysis of the Maastrichtian Patti Formation in Gehuku and Ahoko area, southern Bida Basin, Nigeria: implications for age and paleoenvironments

Detailed palynological examination has been carried out on outcrop shale and claystone samples recovered from Ahoko and Gehuku sections in the Patti Formation, southern Bida Basin. The age and paleoenvironments of deposition of this samples were attempted. A total of 18 samples of shale and claystone were prepared and examined. Palynological results of the examined shale samples show high dominance of terrigenous microflora (spores and pollen), over marine dinoflagellate cysts, mostly species with proximate cyst affinity. A Maastrichtian age was assigned to the formation based on marker palynomorphs taxa: Longapertites marginatus, L. vaneedenburgi, Spinizonocolpites baculatus, Retidiporites magdalensis, Constructipollenitesin effectus, Cingulatisporites ornatus, Distaverrusporites simplex, Echitriporites trianguliformis, Monocolpites marginatus and Foveotriletes margaritae. This assemblage is typical of Maastrichtian species belonging to the palmae provinces of tropical Africa and South American regions. The age was further confirmed by co-occurrence of a well-known age-diagnostic Maastrichtian endemic dinoflagellate cysts species such as Dinogymnium acuminatum. Palynomorphs of environmental value include the fresh water ferns such as Laevigatosporites spp. and Leiotriletes spp., and pollen of palm: Spinizonocolpites baculatus/echinatus, Longapertites marginatus, Mauritidites crassibaculatus and Moncolpites marginatus, which inhabit similar brackish water as the mangrove. The presence of these terrigeneous species alongside the occurrence of the peridinioids dinoflagellate cysts species association such as Dinogymnium spp., Glaphyrocysta spp, Andalusiella sp. and Paleocystodinium spp., indicate deposition in different sedimentary environments, oscillating from marginal marine (brackish water) estuarine in the lower deltaic plain, to non-marine (fresh water mangrove swamp) in the Upper deltaic plain, within the tropical rainforest. The recovered miospores indicated a periodic wet and dry prevailing paleoclimatic conditions. The present findings have contributed to broader paleoclimate studies, helping to establish how climate has influenced sedimentation and biotic communities in the region over time. This also provided context for current climate change discussions by offering a long-term perspective on environmental shifts.

Earth greening and climate change reshaping the patterns of terrestrial water sinks and sources

While vegetation brings positive benefits for climate mitigation and adaptation, the impact of ongoing global greening remains controversial due to its uncertain effects on hydrological cycle. Here, we quantitatively assess the impact of vegetation dynamics on global water availability by proposing a comprehensive framework to quantify the terrestrial water sink and source scores associated with vegetation dynamics. These scores serve as indicators of whether large alterations in water resources have occurred in the lands due to either the greening or degradation of surface vegetation. We use multisource datasets from climate model projections, remote sensing, and local measurements to examine the impact of vegetation dynamics on water availability over the periods of 1982 to 2019 and 2015 to 2100. During historical observation periods, regions such as India and northern China experienced large depletion of water resources as a result of vegetation greening, leading to water scarcity. In the future, a shift is projected for India and northern China, transforming them into regions capable of meeting water demands arising from vegetation greening. This transition is largely attributed to wetting and warming climates. It indicates that trade-off effects between climate and underlying vegetation dynamics may result in strengthening regional hydrological resilience and ensuring the stable status of local water resources. Furthermore, tropical rainforests (except for the Amazon Rainforest) are experiencing greening with minimal impact on local water resources consistently. These insights are valuable for globally identifying optimal locations to implement ecological restoration, facilitating the balance of sustainable water resources and vegetation greening.

From Conservation to Development: A Study of Land Use and Ecological Changes to Vegetation Around the Hainan Tropical Rainforest National Park

Global ecosystems, particularly in biodiversity-rich tropical rainforests, are increasingly under pressure from human activities. As socio-economic development continues and populations steadily grow, the effective planning of areas surrounding national parks has become a global challenge. This study, based on remote sensing data and utilizing landscape ecology tools, such as ArcGIS 10.8, GeoDa 1.20, and Fragstats 4.2, combines spatial statistical methods, trend analysis, and the Hurst index to conduct a long-term analysis and forecast future trends in vegetation ecological quality indicators (VEQI) and landscape pattern changes within and around the Hainan Tropical Rainforest National Park. VEQI changes across various buffer zones were also assessed. Our results show that both arable and built-up land increased, especially from 2002 to 2022. Arable land decreased from 5566.8 km2 to 4796.8 km2, then increased to 5904.6 km2; built-up land expanded from 163.97 km2 to 314.59 km2, reflecting urbanization. Spatiotemporal analysis revealed that 42.54% of the study area experienced significant VEQI changes, with a 24.05% increase (mainly in the northwest) and an 18.49% decrease (mainly in the southeast). The VEQI improvements were consistent across all buffer zones, with the most significant growth in the 7.5 km zone. Landscape indices indicated high fragmentation in coastal areas, while inland areas remained stable, reflecting the tension between conservation and urbanization. These findings provide a theoretical basis for future ecological development and buffer zone policies in the park.

Monitoring Canopy Height in the Hainan Tropical Rainforest Using Machine Learning and Multi-Modal Data Fusion

Biomass carbon sequestration and sink capacities of tropical rainforests are vital for addressing climate change. However, canopy height must be accurately estimated to determine carbon sink potential and implement effective forest management. Four advanced machine-learning algorithms—random forest (RF), gradient boosting decision tree, convolutional neural network, and backpropagation neural network—were compared in terms of forest canopy height in the Hainan Tropical Rainforest National Park. A total of 140 field survey plots and 315 unmanned aerial vehicle photogrammetry plots, along with multi-modal remote sensing datasets (including GEDI and ICESat-2 satellite-carried LiDAR data, Landsat images, and environmental information) were used to validate forest canopy height from 2003 to 2023. The results showed that RH80 was the optimal choice for the prediction model regarding percentile selection, and the RF algorithm exhibited the optimal performance in terms of accuracy and stability, with R2 values of 0.71 and 0.60 for the training and testing sets, respectively, and a relative root mean square error of 21.36%. The RH80 percentile model using the RF algorithm was employed to estimate the forest canopy height distribution in the Hainan Tropical Rainforest National Park from 2003 to 2023, and the canopy heights of five forest types (tropical lowland rainforests, tropical montane cloud forests, tropical seasonal rainforests, tropical montane rainforests, and tropical coniferous forests) were calculated. The study found that from 2003 to 2023, the canopy height in the Hainan Tropical Rainforest National Park showed an overall increasing trend, ranging from 2.95 to 22.02 m. The tropical montane cloud forest had the highest average canopy height, while the tropical seasonal forest exhibited the fastest growth. The findings provide valuable insights for a deeper understanding of the growth dynamics of tropical rainforests.

Detecting biologically invasive species by phenology and topography in tropical moist deciduous forests at satellite remote sensing scale

ABSTRACT Detecting the distribution of invasive species is essential for controlling biological invasions. A biologically-invasive tree, Acacia auriculiformis C. Cunn. ex Benth. is widespread in one of the largest national parks (50.2 km2) in Bangladesh. This evergreen species contrasts with the native deciduous species, particularly the dominant tree, Shorea robusta Gaertner f. We investigated the detectability of invasive forests through seasonal variations of vegetation indices (VIs) using multispectral image classification of remotely sensed imagery. Using Sentinel-2A data (10 m resolution) across four seasons (winter, summer, monsoon, and autumn) in 2022 and 2023, we analysed six common VIs: normalized difference VI (NDVI), enhanced VI (EVI), green chlorophyll index (GCI), green-red VI (GRVI), soil-adjusted VI (SAVI), and atmospherically resistant VI (ARVI). In winter, NDVI, GRVI, and GCI were most effective for extracting A. auriculiformis, while ARVI, NDVI, and GCI were most effective in summer. We used all VIs for each season, along with a composited multi-season image, to detect A. auriculiformis forests using a random forest (RF) classifier on the Google Earth Engine platform. Field observations from 2022 were used to train and validate the classification. The binary and multi-class RF classification of multi-season multispectral images achieved an overall accuracy of 71.1% with a κ coefficient of 0.59 and 76.8% with κ of 0.71, respectively. Incorporating multiple combinations of VIs and elevation (DEM, 12.5 m resolution) into the classification improved overall accuracy to 90% (κ = 0.88) in winter and 83% (κ = 0.80) in multi-season analyses. The variations in VIs between invasive and native vegetation suggested that using multiple VIs with seasonality (phenology) and topography enhanced the detection efficiency of invasive species, particularly when the invasive species exhibited different phenology and topography preferences to native species.

Bauhinia angelae (Leguminosae: Cercidoideae): An overlooked new species from drylands of Northeastern Brazil

The Brazilian Seasonally Dry Tropical Forests and Woodlands represents an important evolutionary unit, widely recognized as a species center of diversification and endemism. The northeastern Brazilian Caatinga is the largest and most diverse SDTFW nucleus, exhibiting a important center of diversification in which the family Leguminosae exhibits the large number in genera and species richness and endemism, in which the genus Bauhinia stands out in species richness. Bauhinia angelae, a new species of shurbs or treelets is described, illustrated, and aspects related to its distribution, conservation status and relationships with morphologically similar species are discussed. Bauhinia angelae is characterized by the presences of triangular stipules, leaflets 3–10 × 2–7 cm, flower buds 2.5–6.5 cm long with the apex capitate and twisted lobes, oblong petals with undulate margins and mature fruits longer than 10 cm long. This new species is distributed in the Brazilian Caatinga between the states of Bahia and Minas Gerais. Additionally, a key to specie included in Bauhinia sect. Pauletia ser. Aculeatae is presented.

Insights on avian life history and physiological traits in Central Africa: ant-following species have young-dominated age ratios in secondary forest

The Congo Basin rainforest and adjacent Lower Guinea Forest constitute the second largest tract of lowland tropical rainforest in the world. As with the rest of the continent, human population is increasing rapidly and forest degradation is ubiquitous. Forest degradation through logging has pervasive negative effects on ecosystems, but selective logging is considered less impactful than clearcutting. Recent research in Afrotropical forest shows that certain avian species and guilds are more affected by selective logging than others (e.g., specialist insectivores such as followers of Dorylus driver ants); however, the mechanisms behind these patterns are poorly known. In an eight-year mist-netting effort in Equatorial Guinea, we caught 1193 birds in primary forest and high-grade selectively logged forest to determine the effect of disturbance on six demographic and physiological measures on birds. We compared five life history and population traits for ten insectivorous species: proportion of breeding and molting birds, molt-breeding overlap, bird age, and a body mass index. We also analyzed the concentrations of the stress hormone feather corticosterone (fCORT) in five species. All three strict ant-following species (Alethe castanea, Chamaetylas poliocephala, Neocossyphus poensis), and the Muscicapid robin Sheppardia cyornithopsis had a higher proportion of first year birds in secondary forest. Furthermore, two ant-followers, A. castanea and C. poliocephala, had a higher proportion of individuals molting in primary forest. Finally, only Illadopsis cleaveri had higher body condition in secondary forest. We found no differences in breeding status, molt-breeding overlap or fCORT between forest types. Using a long-term mist-netting effort, we use measures taken from birds in-the-hand to go beyond insights from point counts alone; we gain valuable insights into the demography and physiology of Afrotropical birds occupying variably degraded lowland tropical rainforest.

Regional variation in the reproductive phenology of a tropical rainforest tree species, Cardwellia sublimis

Abstract Phenology is one of the most reliable tools for understanding the effect of climate change on forests. Although there has been increasing research into the effect of climate on phenological activity, little is known about how phenological patterns for the same species may vary among environments, particularly for tropical species. Here we analysed the reproductive phenology of an important tropical rainforest tree species in northeastern Australia, Cardwellia sublimis, and compared the patterns among seven different sites. We also tested and compared the climate drivers of reproductive phenological activity among sites for this species. Degree of seasonality varied across sites with most sites presenting moderate - high seasonality. Flowering and fruiting peaked in different seasons at the different sites and we found flowering and fruiting phenology were often influenced by different climate drivers at the different sites. Where the climate drivers were the same, the magnitude and direction of the effect of the drivers differed among sites. Precipitation was the most common climate driver of flowering, being significant for all sites, while fruiting was predominantly influenced by temperature and solar radiation. Finally, we found evidence that relationships between climate drivers and phenological patterns were dependent on inter-site differences in climate and geography. Our results demonstrate that species may present varied phenological patterns and varied responses to climate drivers dependent on environmental conditions and site location. These results have important implications for modelling phenological patterns based on limited field information, as well as for understanding species vulnerability to climate change.

Dissecting earthworm diversity in tropical rainforests

Tropical rainforests are among the most emblematic ecosystems in terms of biodiversity. However, our understanding of the structure of tropical biodiversity is still incomplete, particularly for certain groups of soil organisms such as earthworms, whose importance for ecosystem functioning is widely recognised. This study aims at determining the relative contribution of alpha and beta components to earthworm regional diversity at a hierarchy of nested spatial scales in natural ecosystems of French Guiana. For this, we performed a hierarchical diversity partitioning of a large dataset on earthworm communities, in which DNA barcode‐based operational taxonomic units (OTUs) were used as species surrogates. Observed regional diversity comprised 256 OTUs. We found that alpha diversity was lower than predicted by chance, regardless of the scale considered. Community‐scale alpha diversity was on average 7 OTUs. Beta diversity among remote landscapes was higher than expected by chance, explaining as much as 87% of regional diversity. This points to regional mechanisms as the main driver of species diversity distribution in this group of organisms with low dispersal capacity. At more local scales, multiplicative beta diversity was higher than expected by chance between habitats, while it was lower than expected by chance between communities in the same habitat. This highlights the local effect of environmental filters on the species composition of communities. The calculation of a Chao 2 index predicts that as many as 1700 species could be present in French Guiana, which represents a spectacular increase compared with available checklists, and calls into question the commonly accepted estimates of global number of earthworm species.