Tropical Rainforest Research Articles

Correlation between Woody Species and Environmental Variables in a Tropical Forest in Central Laos

The tropical forest biome serves as a significant focal point for conservation endeavors. However, understanding the variations in woody plant composition and the underlying driving factors remains limited. The vegetation gradient within Phou Khao Khouay (PKK) National Park in central Laos presents an intriguing environmental model for investigating these patterns. This study, conducted within PKK National Park, aims to classify woody plant communities of three different forest types: mixed deciduous forest (MDF), dry evergreen forest (DEF), and mixed coniferous forest (MCF), utilizing both the phytosociology approach and multivariate analysis. Data from 32 permanent plots (each measuring 50 m × 50 m) were analyzed, revealing 5,477 tree individuals with a diameter at breast height (DBH) ≥ 5 cm, representing 194 woody species from 64 families and 133 genera. The results indicate significant diversity at the family and genus levels, identifying four distinct plant communities and 44 indicator species based on Tichy and Chytry's phi coefficient method. Stability characterizes the MCF forest type, while the stands of DEF and MDF exhibit differentiation into three communities each. Notably, high heterogeneity in species composition and environmental conditions is evident, with elevation and soil nutrient levels (specifically total phosphorus and total potassium) emerging as primary influencers on species coexistence. The study also highlights correlations between woody plant species composition and topographic and soil variables. These findings underscore the importance of identifying microhabitats conducive to growing and conserving woody plant species within PKK National Park for future research and conservation efforts.

Comparative Phylogeography of Two Specialist Rodents in Forest Fragments in Kenya

The fragmented forests of the Kenya highlands, known for their exceptional species richness and endemism, are among the world’s most important biodiversity hotspots. However, detailed studies on the fauna of these ecosystems—especially specialist species that depend on moist forests, which are particularly threatened by habitat fragmentation—are still limited. In this study, we used mitochondrial genes (cytochrome b and the displacement loop) and a nuclear marker (retinol-binding protein 3) to investigate genetic and morphological diversity, phylogenetic associations, historical divergence, population dynamics, and phylogeographic patterns in two rodent species—the soft-furred mouse (Praomys jacksoni) and the African wood mouse (Hylomyscus endorobae)—across Kenya’s forest landscapes. We found a complex genetic structure, with P. jacksoni exhibiting greater genetic diversity than H. endorobae. The Mt. Kenya P. jacksoni populations are significantly genetically different from those in southwestern forests (Mau Forest, Kakamega Forest, and Loita Hills). In contrast, H. endorobae presented no observable biogeographic structuring across its range. The genetic diversity and geographic structuring patterns highlighted selectively strong effects of forest fragmentation and differing species’ ecological and evolutionary responses to these landscape changes. Our findings further underscore the need for expanded sampling across Kenya’s highland forests to better understand species’ changing diversity and distribution patterns in response to the impacts of human-mediated habitat changes. These insights are critical for informing conservation strategies to preserve biodiversity better in this globally important region.

Hermetic hydrovoltaic cell sustained by internal water circulation.

Numerous efforts have been devoted to harvesting sustainable energy from environment. Among the promising renewable resources, ambient heat exhibits attractive prospects due to its ubiquity and inexhaustibility, and has been converted into electricity through water evaporation-induced hydrovoltaic approaches. However, current hydrovoltaic approaches function only in low-humidity environments and continuously consume water. Herein, we fabricate a hermetic hydrovoltaic cell (HHC) to harvest ambient heat, and have fully addressed the limitations posed by environmental conditions. Meanwhile, for the first time we develop an internal circulation hydrovoltaic mechanism. Taking advantage of the heterogeneous wicking bilayer structure, we verify that inside the hermetic cell, the ambient temperature fluctuation-induced evaporation and further the water circulation can persist, which sustains the hydrovoltaic effect to convert ambient heat into electricity. More importantly, the hermetic design enables the cell to work continuously and reliably for 160 h with negligible water consumption, unaffected by external influences such as wind and light, making it an excellent candidate for extreme situations such as water-scarce deserts, highly humid tropical rain forests, rainy days, and dark underground engineering. These findings provide an easily accessible and widely applicable route for stably harnessing renewable energy, and more notably, offer a novel paradigm toward leveraging low-grade ambient heat energy via circulation design.

Vegetation response to Early Holocene cooling events in the Moervaart region (northwestern Belgium)

A high‐resolution palynological record from northwest Belgium is presented. The record encompasses the second part of the Younger Dryas and the Early Holocene. The basal part of the pollen record reflects a relatively open landscape, characteristic for the Younger Dryas. The transition to the Holocene is marked by an expansion of birch woodland, followed by an expansion of pine in the Late Preboreal (~11.2–10.7 cal. ka BP). Subsequently, the record shows an expansion of mixed deciduous forest with hazel, elm and oak, characteristic for the Boreal (~10.7–8.6 cal. ka BP). Early Holocene forest expansion was interrupted by a number of short‐lived fluctuations, presumably driven by climatic changes. The most distinct event is the Rammelbeek phase (~11.4–11.2 cal. ka BP), during which forest development was temporarily interrupted in favour of grasses, while wildfires increased. Following this climatic event, hunter‐gatherers returned to the area after a period of almost 1.5 millennia of low population density. They most likely were attracted by the increased temperatures and abundance of edible plants present in the birch‐pine forests and on the banks of the river Kale/Durme. A temporary expansion of pine during the Boreal (~10.7–8.6 cal. ka BP) may correspond with the 9.3‐ka event. At this time, superimposed on a trend of gradual infilling of the channel, a temporary change to drier conditions is observed. The significant drop in the number of prehistoric sites in the Moervaart region clearly cannot be attributed to this short‐term climatic event alone but was most likely caused by a combination of environmental changes, such as the decreasing availability of hazelnuts as well as freshwater and edible (semi‐)aquatic plants as the Kale/Durme river gradually turned dry. The study provides insight into, partly climate‐driven, Early Holocene environmental changes and the effect this may have had on human occupation.

Genotypic and phylogeographic insights into a pre-epidemic variant of Wesselsbron virus detected in sylvatic Aedes mcintoshi from Semuliki Forest, Uganda.

Wesselsbron virus (WSLV) is a neglected mosquito-borne virus within the yellow fever subgroup in the genus Orthoflavivirus of the Flaviviridae family. Despite being primarily a veterinary pathogen able to cause stillbirths, congenital malformations, and mortality in ruminants, WSLV also infects humans, causing a usually self-limiting febrile illness, or may lead to neurological complications in rare cases. WSLV causes sporadic outbreaks in Southern Africa, but findings in mosquitoes from other African countries suggest a wider distribution. Here, we report the detection and isolation of WSLV from an Aedes mcintoshi mosquito collected in a pristine ecosystem within Semuliki National Park, western Uganda. The detected strain M5937-UG-2018 was impaired in infectivity, replication, and production of infectious particles in cell lines derived from different hosts compared to an epidemic reference strain, SA H177. Full-genome sequencing by next-generation sequencing from the mosquito homogenate revealed a maximum nucleotide identity of 98.1% to a WSLV isolate from a human sample collected in South Africa in 1996. M5937-UG-2018 grouped in phylogenetic analyses with strains from South Africa and Senegal. Reconstruction of the temporal and spatial dispersal of WSLV across Africa estimated a likely origin of WSLV in South Africa in the early 19th century and spread in Southern Africa in the following decades. Long-distance movement toward Western and Eastern Africa was modeled to have occurred in the early 21st century. However, displacing the origin of M5937-UG-2018 did not decrease the likelihood of the model supporting the hypothesis that WSLV is widely distributed in Africa.IMPORTANCEWSLV is a neglected mosquito-borne virus causing teratogenicity in ruminants and febrile illness in humans. WSLV is mainly endemic to Southern Africa, but findings in other regions suggest a wider distribution on the continent. Knowledge of the distribution of WSLV is impaired as differential diagnostics are rarely performed in livestock and humans presenting with symptoms compatible with WSLV infection. Our work investigating viral infections in mosquitoes from a remote tropical rainforest region demonstrates that WSLV is endemic in Uganda. The isolated virus was less infective and showed lower replication ability in vitro compared to an epidemic isolate from South Africa. Phylogeographic reconstruction of spatial and temporal movements, along with the displacement of the origin of the newly detected strain, suggests that WSLV may be widely distributed across Africa. Our data show that the geographic distribution of WSLV and its impact on human and animal health are likely underestimated.

Vector-borne diseases on Borneo island: a scoping review.

Borneo, the third largest island in the world, is facing a significant burden of emerging and re-emerging vector-borne diseases due to rapid changes in primary tropical rainforests and urban landscapes. These vector-borne diseases include the endemic epidemic cycles that occur in the more populated and urbanized areas, as well as the possible transmission through enzootic and sylvatic transmission cycles that occur mainly in the overlapping landscapes or among the indigenous population in the forest. The island will be changed significantly in the future due to the increase in human activities, especially mega events such as the relocation of the Indonesian capital to Nusantara in East Kalimantan Borneo, increasing urbanization, agriculture, hydropower projects, ecotourism activities in Sabah, North Borneo, and Sarawak, Central and South Borneo. Therefore, an overview of the current situation of vector-borne diseases is crucial for the next possible epidemic preparedness. This study conducted the PRISMA-ScR scoping review and formulated a set of research questions to identify current trends in vector-borne diseases in Borneo. These questions aim to identify which diseases have been studied, what geographical areas have been covered by the research, how the One Health approach-encompassing human, animal and environmental factors-is integrated, and what gaps and challenges exist in addressing these diseases. A total of 2241 references were screened for eligibility and 117 articles were selected for review. The majority of the materials focused on mosquitoes and malaria, and the One Health elements focused mainly on humans. This review has identified the most and least studied vector-borne diseases and highlighted some of the gaps in knowledge and research on vector-borne diseases on the island of Borneo. Future studies should particularly focus on other neglected diseases such as Zika, chikungunya, Japanese encephalitis, filariasis and tick-borne diseases. In addition, advanced surveillance systems will be developed to improve early detection and response specifically for remote regions where vector-borne diseases are endemic or emerging.

Trends in Urban Wild Meat Trade of Chelonians (Turtles and Tortoises) in the Peruvian Amazon

Culturally, chelonians are important sources of nutrition and income for rural and urban people in tropical rainforests, but urban trade can cause declines in wild populations. This study analyses the urban chelonian trade and its trends to better understand the impact on free-living populations in the Northern Peruvian Amazon. We studied the urban trade of wild chelonians by conducting 526 days of participant observation and structured questionnaires with the main chelonian vendors in the wet markets of Iquitos between 2006 and 2018. The trade of chelonians decreased by −161.6%, from 22,694 individuals in 2006/07 to 8657 individuals in 2017/18. Chelonoidis denticulatus was the species sold the most (86.3%), followed by Podocnemis unifilis (13.6%). Podocnemis expansa was only sold in 2006/07. River turtle sales increased in the dry season, while sales of Chelonoidis denticulatus decreased. Turtles were the most expensive meat sold in urban markets: 49.7% more expensive than the most frequently consumed fish, Prochilodus nigricans, and 48.4% more expensive than poultry. Turtles represented only 0.19% (SD 0.23) of the index of domestic meat and fish consumption per capita. River turtle eggs are sold by a different set of vendors, and in 2017/18, 570,229 eggs were traded in the market of Belén in Iquitos, equivalent to an approximate lay of 10,418 P. unifilis and 1178 P. expansa females. The high magnitude of the trade of river turtle eggs together with the reduction in their meat trade suggests a prioritization of egg sales, which should improve the conservation of adults, since meat sales can be detrimental to chelonian populations.

First records of moss-feeding aphids (Hemiptera: Sternorrhyncha: Aphididae) from Hungary

Four species of moss-feeding aphids were captured by Berlese samples collected in Heves county, NE Hungary. These data are establishing the first Hungarian records of moss-dwelling aphids, all the four species and three genera are reported from the country for the first time. Muscaphis (Aspidaphium) eschirichi (Börner, 1939) was yielded from a colony of Palustriella commutata (Hedw.) Ochyra collected from rock in a karst spring outlet, Muscaphis (Muscaphis) musci Börner, 1933 was yielded from colonies of Hypnum cupressiforme Hedw. collected from bark of Quercus pubescens Wild. in an open karst forest, Pseudacaudella rubida (Börner, 1939) was yielded from both of the above mosses, while a Myzodium sp. was yielded from a colony of Hypnum cupressiforme mixed with a single stem of Brachythecium salebrosum (Hoffm. ex F.Weber & D.Mohr) Schimp., collected from bark of dead trunk of Quercus cerris L. in a mixed deciduous forest. All moss species are new host records for the corresponding species. Myzodium sp. explain some distinctive characters different from the only European species of its genus and probably belong to an undescribed species, but we are avoiding of describing it on the basis of the single adult captured. Distinctive morphological and biological characteristics of the Hungarian specimens of the four aphid species are discussed and illustrated. A list of the accompanying taxa yielded from the Berlese samples are listed in a table.

Suspended soils enrich local forest floor soils during the rainy season in a tropical monsoon rainforest of Hainan Island, South China

Suspended soils enrich local forest floor soils during the rainy season in a tropical monsoon rainforest of Hainan Island, South China

Disentangling the Complex Effects of Seasonal Drought, Floor Mass, and Roots on Soil Microbial Biomass in a Subtropical Moist Forest

Severe seasonal droughts driven by global climate change significantly alter the cycling of carbon and nutrients in forest ecosystems, while the investigation into the impacts of floor mass and plant roots on soil microbial biomass within the context of recurrent seasonal droughts is still rare. To investigate the environmental determinants governing soil microbial biomass with the escalating severity of seasonal droughts, we conducted a study in a montane subtropical moist evergreen broad-leaved forest in southwestern China from June 2019 to May 2023. The study results revealed that soil microbial biomass, as well as soil moisture, floor mass, and plant roots, showed an apparent single-hump modal within one year. In the comparative analysis of the soil microbial biomass fluctuation amplitudes across control and watered plots, a discernible disparity was observed, indicating significant differences in microbial biomass dynamics between the respective experimental conditions. The pooled data revealed a statistically significant influence of seasonal drought, floor mass, plant roots, and their reciprocal interactions on the soil microbial biomass, highlighting these factors as pivotal determinants of microbial community dynamics. This study elucidates the interactive regulatory mechanisms by which seasonal drought, floor mass, and plant roots collectively modulate soil microbial biomass within tropical and subtropical forests, offering insights into the complex ecological processes governing microbial community dynamics. This interactive regulation might influence the trajectory of plant species and soil microbial communities, facilitating their adaptive development and evolutionary responses.

Aridity and forest age mediate landscape scale patterns of tropical forest resistance to cyclonic storms

Abstract Cyclonic storms, or hurricanes, are expected to intensify as ocean heat energy rises due to climate change. Ecological theory suggests that tropical forest resistance to hurricanes should increase with forest age and wood density. However, most data on hurricane effects on tropical forests come from a limited number of well‐studied long‐term monitoring sites, restricting our capacity to evaluate the resistance of tropical forests to hurricanes across broad environmental gradients. In this study, we assessed whether forest age and aridity mediate the effects of hurricanes Irma and Maria in Puerto Rico, Vieques and Culebra islands. We leveraged functional trait data for 410 tree species, remotely sensed measurements of canopy height and cover, along with data on forest stand characteristics of 180 of 338 forest monitoring plots, each covering an area of 0.067 ha. The plots represent a broad mean annual precipitation (MAP) gradient from 701 to 4598 mm and a complex mosaic of forest age from 5 to around 85 years since deforestation. Hurricanes resulted in a 25% increase in basal area mortality rates, a 45% decrease in canopy height and a 21% reduction in canopy cover. These effects intensified with forest age, even after considering proximity to the hurricane path. The links between forest age and hurricane disturbances were likely due the prevalence of tall canopies. Tall forest canopies were strongly linked with low community‐weighted wood density (WD). These characteristics were on average more common in moist and wet forests (MAP >1250 mm). Conversely, dry forests were dominated by short species with high wood density (WD > 0.6 g cm−3) and did not show significant increases in basal area mortality rates after the hurricanes. Synthesis. Our findings show that selection towards drought‐tolerant traits across aridity gradients, such as short stature and dense wood, enhances resistance to hurricanes. However, forest age modulated responses to hurricanes, with older forests being less resistant across the islands. This evidence highlights the importance of considering the intricate links between ecological succession and plant function when forecasting tropical forests’ responses to increasingly strong hurricanes.

Mapping human footprint changes over Qingzang Plateau

Mapping human footprint (HF) is crucial for understanding the cumulative anthropogenic pressures on the environment. However, its effectiveness is often hampered by the absence of fine-scale, high-quality spatio-temporal datasets. Addressing this gap, we present the first annual HF maps for the Qingzang Plateau (QP) from 1990 to 2020, at a 100 m × 100 m resolution, boasting an accuracy exceeding 80%. Our findings reveal that the QP's human-induced modifications were relatively low, with a median HF of 3.39 in 2020, significantly lower than the global average of 7.56. The northeast and mid-south regions of the QP emerged as hotspots for anthropogenic impact. Notably, over two-thirds (68.2%) of the QP registered an HF score below 4, classifying them as largely intact. However, the QP's average HF score has escalated more swiftly than the global mean (0.0348/yr vs. 0.0186/yr), particularly in the last decade, indicating escalating human pressures. In terms of stability, montane grasslands and shrublands comprised 75.1% of moderately or highly altered biomes in 2020. In contrast, tropical and subtropical moist broadleaf forests witnessed the most substantial HF increases. Encouragingly, 26.29% of the QP experienced HF reductions over the past thirty years, highlighting potential conservation opportunities. Conversely, a significant HF increase across 36.59% of the QP underscores the pressing need to mitigate the adverse effects of intensified human activities. Our HF maps will be conducive to improve understanding the profound impacts wrought by human activities on the QP, and support the conservation planning and resource management needs, as well as decision-making related to restoration objectives.

A Theoretical Framework to Quantify Ecosystem Pressure-Volume Relationships.

'Water potential' is the biophysically relevant measure of water status in vegetation relating to stomatal, canopy and hydraulic conductance, as well as mortality thresholds; yet, this cannot be directly related to measured and modelled fluxes of water at plot- to landscape-scale without understanding its relationship with 'water content'. The capacity for detecting vegetation water content via microwave remote sensing further increases the need to understand the link between water content and ecosystem function. In this review, we explore how the fundamental measures of water status, water potential and water content are linked at ecosystem-scale drawing on the existing theory of pressure-volume (PV) relationships. We define and evaluate the concept and limitations of applying PV relationships to ecosystems where the quantity of water can vary on short timescales with respect to plant water status, and over longer timescales and over larger areas due to structural changes in vegetation. As a proof of concept, plot-scale aboveground vegetation PV curves were generated from equilibrium (e.g., predawn) water potentials and water content of the above ground biomass of nine plots, including tropical rainforest, savanna, temperate forest, and a long-term Amazonian rainforest drought experiment. Initial findings suggest that the stored water and ecosystem capacitance scale linearly with biomass across diverse systems, while the relative values of ecosystem hydraulic capacitance and physiologically accessible water storage do not vary systematically with biomass. The bottom-up scaling approach to ecosystem water relations identified the need to characterise the distribution of water potentials within a community and also revealed the relevance of community-level plant tissue fractions to ecosystem water relations. We believe that this theory will be instrumental in linking our detailed understanding of biophysical processes at tissue-scale to the scale at which land surface models operate and at which tower-based, airborne and satellite remote sensing can provide information.

Assessment of Water-Related Ecosystem Services and Beneficiaries in the Hainan Tropical Rainforest National Park

Tropical rainforests are of vital importance to the environment, as they contribute to weather patterns, biodiversity and even human wellbeing. Hence, in the face of tropical deforestation, it becomes exigent to quantify and assess the contribution of ecosystem services associated with tropical rainforests to the environment and especially to the people. This study adopted a nuanced approach, different from traditional economic valuations, to estimate the water-related ecosystem services (WRESs) received by the people from 2010 to 2020 in the Hainan Tropical Rainforest National Park (HTRNP). The study focused on water yield, soil conservation, and water purification using InVEST, the SCS-CNGIS model, and spatial analysis. The results show (1) significant land cover changes within the HTRNP, as forest decreased by 4433 ha and water bodies increased by 4047 ha, indicating the active presence of human activities. However, land cover changes were more pronounced within the 5 km buffer area around the HTRNP, suggesting the effectiveness of the tropical rainforest conservation efforts in place. (2) The water yield of the HTRNP in the years studied decreased by 307.03 km3, based on the water yields in 2010 and 2020, which were 5625.7 km3 and 5318.7 km3, respectively. (3) Change detection showed that runoff mitigation in the rainforest has a negative mean (−0.21), indicating a slight overall decrease in soil conservation and runoff mitigation in the rainforest from 2010 to 2020; however, the higher curve number indicates areas susceptible to surface runoff. (4) The ecological effectiveness of water purification to absorb and reduce nitrogen load was better in 2020 (145,529 kg/year), as it was reduced from 506,739 kg/year in 2010, indicating improved water quality. (5) Population growth is more pronounced in areas with high water yields. Overall, the proposed framework has shown that the water yield potential of the HTRNP can meet the water consumption demands of people and industries situated within the buffer area. However, analysis of the study shows that it does not meet the crop water requirements. This study provides insights for decision makers in identifying potential beneficiaries and the essence of effective area-based conservation measures, and the proposed framework can be applied to any area of interest, offering a different approach in ecosystem services assessment.

Soil total phosphorus mediate the assembly processes of rhizosphere microbial communities of ficus species in a tropical rainforest

Revealing the assembly processes of plant rhizosphere microbial communities and the underlying influencing factors is essential for understanding the biodiversity and function of forest ecosystem. However, it remains unclear how deterministic and stochastic processes shape community structure and their relative importance in phosphorus-limited tropical environments. Here, we investigated the diversity, composition, and assembly processes of rhizosphere microbial communities of Ficus species in the Xishuangbanna region of southwest China, using methods such as high-throughput sequencing, variance partitioning analysis and null model analysis. We found that the community assembly processes of bacteria and fungi were primarily dominated by deterministic processes, with the fungal group being more deterministic than the bacteria group. Soil total phosphorus (TP) was the primary determinant of the composition and assembly of the rhizosphere microbial community, explaining 12.58% and 21.35% of the compositional variation in bacterial and fungal communities, respectively, and accounting for 14% of the microbial community assembly, but has a minor impact on their alpha diversity. This study highlights the distinct environmental driving factors of community composition and community assembly. The exposed positive relationship between soil TP and microbial deterministic process has inspiration for link of microbial community functions to soil function and sustainable forest management.

Savanna Plants Have a Lower Hydraulic Efficiency than Co-Occurring Species in a Rainforest

A plant species can have diverse hydraulic strategies to adapt to different environments. However, the water transport divergence of co-occurring species in contrasting habitats remains poorly studied but is important for understanding their ecophysiology adaptation to their environments. Here, we investigated whole-branch, stem and leaf water transport strategies and associated morphology traits of 11 co-occurring plant species in Yuanjiang valley-type savanna (YJ) with dry–hot habitats and Xishuangbanna tropical seasonal rainforest (XSBN) with wet–hot habits and tested the hypothesis that plants in YJ have a lower water transport efficiency than co-occurring species in XSBN. We found high variation in whole-branch, stem and leaf hydraulic conductance (Kshoot; Kstem and Kleaf) between YJ and XSBN, and that Kstem was significantly higher than Kleaf in these two sites (Kstem/Kleaf: 16.77 in YJ and 6.72 in XSBN). These plants in YJ with significantly lower Kshoot and Kleaf but higher sapwood density (WD) and leaf mass per area (LMA) showed a lower water transport efficiency regarding less water loss and the adaptation to the dry–hot habitat compared to co-occurring species in XSBN. In contrast, these co-occurring plants in XSBN with higher Kshoot and Kleaf but lower WD and LMA tended to maximize water transport efficiency and thus growth potential in the wet–hot habitat. Our findings suggest that these co-occurring species employ divergent hydraulic efficiency across YJ and XSBN so that they can benefit from the contrasting hydraulic strategies in adaptation to their respective habitats.

Runoff Change Characteristics and Response to Climate Variability and Human Activities Under a Typical Basin of Natural Tropical Rainforest Converted to Monoculture Rubber Plantations

Climate variability and human activities are major influences on the hydrological cycle. However, the driving characteristics of hydrological cycle changes and the potential impact on runoff in areas where natural forests have been converted to rubber plantations on a long-term scale remain unclear. Based on this, the Mann–Kendall (MK) and Pettitt breakpoint tests and the Double Mass Curve method were employed to identify the variation characteristics and breakpoints of precipitation (P), potential evapotranspiration (ET0), and runoff depth (R) in the Wanquan River Basin (WQRB) during the 1970–2016 period. The changes in runoff attributed to P, ET0, and the catchment characteristics parameter (n) were quantified using the elastic coefficient method based on the Budyko hypothesis. The results revealed that the P and R in the WQRB exhibited statistically insignificant decreasing trends, while ET0 displayed a significant increasing trend (p < 0.05). The breakpoint of runoff changes in the Jiabao and the Jiaji stations occurred in 1991 and 1983, respectively. The runoff changes show a negative correlation with both the n and ET0, while exhibiting a positive correlation with P. Moreover, it is observed that P and ET0 display higher sensitivity towards runoff changes compared to n. The decomposition analysis reveals that in the Dingan River Basin (DARB), human activities account for 53.54% of the runoff changes, while climate variability contributes to 46.46%. In the Main Wanquan River Basin (MWQRB), human activities contribute to 46.11%, whereas climate variability accounts for 53.89%. The research findings suggest that runoff is directly reduced by climate variability (due to decreased P and increased ET0), while human activities indirectly contribute to changes in runoff through n, exacerbating its effects. Rubber forest stands as the prevailing artificial vegetation community within the WQRB. The transformation of natural forests into rubber plantations constitutes the primary catalyst for the alteration of n in the WQRB. The research findings provide important reference for quantifying the driving force of hydrological changes caused by deforestation, which is of great significance for sustainable management of forests and water resources.

Two centuries of ornithological exploration of the Rio Doce Basin, southeastern Brazil. Part II—A catalogue of its birds and a gazetteer

The Rio Doce Hydrographic Basin (RDB) lies almost completely in the Brazilian Atlantic Forest, a highly threatened tropical rainforest. The RDB has suffered dramatic anthropogenic impacts during the last two centuries and is currently one of the most degraded regions in southeastern Brazil. In this paper, we gathered 140,742 bird records collected since the early 19th by more than two thousand naturalists, professional scientists, and citizen scientists. This vast database was compiled from several sources, including published literature, unpublished technical reports, natural history museums, and citizen science platforms. After checking and standardizing the database, we found high species richness in the RDB, with 689 species recorded to date, from which 675 (98%) were documented by specimens or digital vouchers. This database is presented as a detailed catalogue, including maps containing all localities in which each species has been recorded. We present text accounts for 40 noteworthy species recorded in the RDB, and a complete gazetteer for the 636 localities sampled. Preliminary analyses reveal that the RDB avifauna suffered a dramatic change in its species composition during the last two centuries, mostly due to human activity. Highly sensitive species associated to pristine forests vanished, while species associated to dry and open habitat expanded their ranges in the RDB. Finally, in addition to thoroughly characterization of the RDB avifauna, this paper provides the basis for a series of studies about the avifauna of one of the hottest hotspots of biodiversity in the entire Neotropical region.

In thermotolerance tests of tropical tree leaves, the chlorophyll fluorescence parameter Fv/Fm measured soon after heat exposure is not a reliable predictor of tissue necrosis.

Tropical rainforests are hot and may be particularly sensitive to ongoing anthropogenic global warming. This has led to increased interest in the thermotolerance of tropical trees. Thermotolerance of leaves of two tropical tree species, Terminalia catappa and Coccoloba uvifera, was determined by exposing leaf samples to 15-min heat treatments, followed by measurements of potential photosystem II quantum yield (dark-adapted value of variable/maximum chlorophyll a fluorescence, Fv/Fm) after 24 h and 14 days, and visible damage (necrosis) after 14 days. T50 (24 h), the temperature at which Fv/Fm declined by 50% 24 h after heat treatments, was associated with only ~10% leaf area damage in C. uvifera and no damage in T. catappa. In neither species was leaf necrosis observed at T5 (24 h), the temperature at which Fv/Fm declined by 5%. In both species, temperatures significantly higher than T50 (24 h) were required for 50% leaf area necrosis to occur. T50 (14 days) was a better proxy of visible leaf damage than T50 (24 h). The relationship between heat-induced Fv/Fm decline and tissue necrosis varies among species. In species surveys of leaf thermal tolerances, calibration of the Fv/Fm assay against the necrosis test is recommended for each species under investigation. Fv/Fm measurements soon after heat exposure do not reliably predict irreversible heat damage and may thus not be suitable to model and predict the thermostability of tropical forest trees.

Long‐Term Impacts of Selective Logging in a Tropical Rainforest in the East Region of Cameroon

ABSTRACTAlthough selective logging has become the primary cause of degradation in many African countries, little is known about its long‐term effects. This study investigated the long‐term effects of selective logging on forest tree species diversity and dynamics in the East Region of Cameroon. Six permanent monitoring plots of 1 ha each in unlogged and logged forests were established in 2005 and a recensus in 2011. Each 1 ha plot was divided into 25, 20 × 20 m quadrats. Each 20 × 20 m quadrat was further divided into 16, 5 × 5 m subquadrats, where the diameter at breast height (DBH) of all trees ≥ 2 cm was measured. There was a decrease in plant species density and richness in all forest types. Sloetiopsis usambarensis was the most important species in the unlogged forests and forests logged 21 years ago. The most important family was Putrangivaceae, Euphorbiaceae and Violaceae in the unlogged forests and forests logged 11 and 21 years ago, respectively. The frequency distribution of stem size classes indicated a reversed J‐shape of tropical forests. The above ground biomass (AGB) recovered more than 50% in all forests, and the unlogged forest had the highest AGB (961.8 Mg/ha). Larger stems indicated a forest at a stage of recovery from disturbance. Silvicultural management should be considered.