Search

Future climate presents conflicting implications for forest biomass. We evaluate how plant hydraulic traits, elevated CO2 levels, warming, and changes in precipitation affect forest primary productivity, evapotranspiration, and the risk of hydraulic failure. We used a dynamic vegetation model with plant hydrodynamics (FATES-HYDRO) to simulate the stand-level responses to future climate changes in a wet tropical forest in Barro Colorado Island, Panama. We calibrated the model by selecting plant trait assemblages that performed well against observations. These assemblages were run with temperature and precipitation changes for two greenhouse gas emission scenarios (2086-2100: SSP2-45, SSP5-85) and two CO2 levels (contemporary, anticipated). The risk of hydraulic failure is projected to increase from a contemporary rate of 5.7% to 10.1-11.3% under future climate scenarios, and, crucially, elevated CO2 provided only slight amelioration. By contrast, elevated CO2 mitigated GPP reductions. We attribute a greater variation in hydraulic failure risk to trait assemblages than to either CO2 or climate. Our results project forests with both faster growth (through productivity increases) and higher mortality rates (through increasing rates of hydraulic failure) in the neo-tropics accompanied by certain trait plant assemblages becoming nonviable.

Non-structural carbohydrates (NSCs) are building blocks for biomass and fuel metabolic processes. However, it remains unclear how tropical forests mobilize, export, and transport NSCs to cope with extreme droughts. We combined drought manipulation and ecosystem 13CO2 pulse-labeling in an enclosed rainforest at Biosphere 2, assessed changes in NSCs, and traced newly assimilated carbohydrates in plant species with diverse hydraulic traits and canopy positions. We show that drought caused a depletion of leaf starch reserves and slowed export and transport of newly assimilated carbohydrates below ground. Drought effects were more pronounced in conservative canopy trees with limited supply of new photosynthates and relatively constant water status than in those with continual photosynthetic supply and deteriorated water status. We provide experimental evidence that local utilization, export, and transport of newly assimilated carbon are closely coupled with plant water use in canopy trees. We highlight that these processes are critical for understanding and predicting tree resistance and ecosystem fluxes in tropical forest under drought.

Summary Tropical forests play a large role in the global carbon cycle by annually absorbing 30% of our annual carbon emissions. However, these forests have evolved under relatively stable temperature conditions and may be sensitive to current climate warming. Few experiments have investigated the effects of warming on large, mature trees to better understand how higher temperatures affect these forests in situ. We targeted four tree species (Endiandra microneura, Castanospermum australe, Cleistanthus myrianthus and Myristica globosa) of the Australian tropical rainforest and warmed leaves in the canopy by 4°C for 8 months. We measured temperature response curves of photosynthesis and respiration, and determined the critical temperatures for chloroplast function based on Chl fluorescence. Both stomatal conductance and photosynthesis were strongly reduced by 48 and 35%, respectively, with warming. While reduced stomatal conductance was likely in response to higher vapour pressure deficit, the biochemistry of photosynthesis responded to higher temperatures via reduced Vcmax25 (−28%) and Jmax25 (−29%). There was no shift of the Topt of photosynthesis. Concurrently, respiration rates at a common temperature did not change in response to warming, suggesting limited respiratory thermal acclimation. This combination of physiological responses to leaf warming in mature tropical trees may suggest a reduced carbon sink with future warming in tropical forests. [ABSTRACT FROM AUTHOR]

Canopy height is a key indicator of tropical forest structure. In this study, we present a deep learning application to map canopy height in French Guiana using freely available multi-source satellite data (optical and radar) and complementary environmental information. The potential of a U-Net architecture trained on sparse and unevenly distributed GEDI data to generate a continuous canopy height map at a regional scale was assessed. The developed model, named CHNET , successfully produced a canopy height map of French Guiana at a 10-m spatial resolution, achieving relatively good accuracy compared to a validation airborne LiDAR scanning (ALS) dataset. The study demonstrates that relevant environmental descriptors, namely, height above nearest drainage (HAND) and forest landscape types (FLT), significantly contribute to the model's accuracy, highlighting that these descriptors bring important information on canopy structural properties and that the CHNET framework can efficiently use this information to improve canopy height prediction. Another critical aspect highlighted is the necessity of addressing GEDI data inaccuracies and geolocation uncertainties, which is essential for any GEDI-based application. However, challenges remain, particularly in characterizing tall canopies, as our CHNET model exhibits a tendency to underestimate canopy heights greater than 35 m. A large part of this error arises from the use of GEDI measurements as reference, given the fact these data exhibit certain saturation in tropical biomes. Future improvements in the analysis of GEDI signal as well as the implementation of robust models are essential for better characterization of dense and tall tropical forest ecosystems. [ABSTRACT FROM AUTHOR]

Biogeographic context, such as biome type, has a critical influence on ecological resilience, as climatic and environmental conditions impact how communities respond to anthropogenic threats. For example, land‐use change causes a greater loss of biodiversity in tropical biomes compared to temperate biomes. Furthermore, the nature of threats impacting ecosystems varies geographically. Therefore, monitoring the state of biodiversity at a high spatial resolution is crucial to capture variation in threat–responses caused by biogeographical context. However such fine‐scale ecological data collection could be prohibitively resource intensive. In this study, we aim to find the spatial scale that could best capture variation in community‐level threat responses whilst keeping data collection requirements feasible. Using a database of biodiversity records with extensive global coverage, we modelled species richness and total abundance (the responses) across land‐use types (reflecting threats), considering three different spatial scales: biomes, biogeographical realms, and regional biomes (the interaction between realm and biome). We then modelled data from three highly sampled biomes to ask how responses to threat differ between regional biomes and taxonomic group. We found strong support for regional biomes in explaining variation in species richness and total abundance compared to biomes or realms alone. Our biome case studies demonstrate that there is variation in magnitude and direction of threat responses across both regional biomes and taxonomic group, although the interpretation is limited by sampling bias in the literature. All groups in tropical forest showed a consistently negative response, whilst many taxon‐regional biome groups showed no clear response to threat in temperate forest and tropical grassland. Our results provide the first empirical evidence that the taxon‐regional biome unit has potential as a reasonable spatial unit for monitoring how ecological communities respond to threats and designing effective conservation interventions to bend the curve on biodiversity loss. [ABSTRACT FROM AUTHOR]

Young tropical secondary forests play an important role in the local and global carbon cycles because of their large area and rapid biomass accumulation rates. This study examines how environmental conditions and forest attributes shape biomass compartments and the productivity of young tropical secondary forests. We compared 36 young secondary forest stands that differed in the time since agricultural land abandonment (2.3–3.6 years) from dry and wet regions in Ghana. We quantified biomass stocks in living and dead stems, roots, and soil, and aboveground biomass and litter productivity. We used structural equation models to evaluate how macroclimate, soil nutrients (N, P), and forest attributes (structure, diversity, and functional composition) affect ecosystem functioning. After three years of succession, tropical wet forests stored on average 115 t biomass ha−1 (the sum of aboveground living and dead biomass, belowground fine root biomass, and soil organic matter), and dry forests stored 99 t ha−1. These values represent 31% (in the wet forest) and 39% (in the dry forest) of the biomass compared with neighboring old‐growth forests. The majority of forest ecosystem biomass was stored in the soil (70%) and aboveground living vegetation (25%). Macroclimate strongly shaped forest attributes, which in turn determined biomass stocks and productivity. Soil phosphorus strongly increased litter production and soil organic matter, confirming that it is a limiting element in tropical ecosystems. Tree density and species diversity increased forest biomass stocks, suggesting crown packing and complementary resource use enhance forest functioning. A more conservative trait composition (high wood density) increased biomass stocks but reduced productivity, indicating that quantity, identity, and quality of species affect ecosystem functioning. [ABSTRACT FROM AUTHOR]

Wet tropical forests play an important role in the global carbon (C) cycle, but given current rates of land‐use change, nitrogen (N) and phosphorus (P) limitation could reduce productivity in regenerating forests in this biome. Whereas the strong controls of climate and parent material over forest recovery are well known, the influence of vegetation can be difficult to determine. We addressed species‐specific differences in plant traits and their relationships to ecosystem properties and processes, relevant to N and P supply to regenerating vegetation in experimental plantations in a single site in lowland wet forest in Costa Rica. Single‐tree species were planted in a randomized block design, such that climate, soil (an Oxisol), and land‐use history were similar for all species. In years 15–25 of the experiment, we measured traits regarding N and P acquisition and use in four native, broad‐leaved, evergreen tree species, including differential effects on soil pH, in conjunction with biomass and soil stocks and fluxes of N and P. Carbon biomass stocks increased significantly with increasing soil pH (p = 0.0184, previously reported) as did biomass P stocks (p = 0.0011). Despite large soil N pools, biomass P stocks were weakly dependent on traits associated with N acquisition and use (N2 fixation and leaf C:N, p < 0.09). Mass‐balance budgets indicated that soil organic matter (SOM) could supply the N and P accumulated in biomass via the process of SOM mineralization. Secondary soil P pools were weakly correlated with biomass C and P stocks (R = 0.47, p = 0.08) and were large enough to have supplied sufficient P in these rapidly growing plantations, suggesting that alteration of soil pH provided a mechanism for liberation of soil P occluded in organo‐mineral soil complexes and thus supply P for plant uptake. These results highlight the importance of considering species' effect on soil pH for restoration projects in highly weathered soils. This study demonstrates mechanisms by which individual species can alter P availability, and thus productivity and C cycling in regenerating humid tropical forests, and the importance of including traits into global models of element cycling. [ABSTRACT FROM AUTHOR]

As long‐lived tropical trees grow into the multi‐layered canopy and face different environmental conditions, the relationships between leaf traits and whole‐plant survival can vary over ontogeny. We tested the strength and direction of the relationships between leaf traits and long‐term survival data across life stages for woody species from a subtropical forest in Puerto Rico. Trait–survival relationships were largely consistent across ontogeny with conservative traits leading to higher survival rates. The stage‐specific relationship R2 increased by up to one order of magnitude compared to studies not considering ontogenetic trait variations. Stage‐specific traits were significant predictors of their corresponding stage‐specific survival: Seedlings traits were better predictors of seedling survival than adult traits, and adult traits were better predictors of maximum adult survival than seedling traits. Our results suggest that stage‐specific leaf traits reflect different strategies over ontogeny and can substantially improve predictability of survival models in tropical forests. [ABSTRACT FROM AUTHOR]

Tropical forests are vital for global biodiversity and climate stability, but the political economy of deforestation and land-use change constantly challenges their integrity. In this article, we analyse 50 years of policy development in the municipality Marqués de Comillas, located in Selva Lacandona, Chiapas, Mexico, to understand how development and conservation priorities have evolved, interacted, and shaped land-use in a tropical forest frontier. By analysing peer-reviewed literature and empirical data, we identify five phases of policy continuity and change that have produced diverse socio-environmental outcomes. We reveal a persistent state-led prioritisation of rural development over environmental concerns, pursued through policies promoting settlements and agricultural expansion and exacerbated by external market forces. This focus has caused substantial ecosystem degradation and deforestation without significant livelihood improvements. Recent conservation initiatives, such as payment for ecosystem services, show potential for challenging the status quo by offering alternative livelihood opportunities benefiting both people and ecosystems. [ABSTRACT FROM AUTHOR]

The vulnerability segmentation hypothesis proposes that the hydraulic function of expensive stems can be protected by sacrificing cheap leaves, which has been proven to be a key strategy to survive drought for woody species from arid regions. Climate change has caused increasing severe droughts in relatively humid tropical‐subtropical forests. However, whether vulnerability segmentation (measured as the differences in embolism resistance between stem and leaf; P50leaf–stem) plays a role in the hydraulic strategy of tropical‐subtropical woody plants remains unclear.We investigated 12 key hydraulically related traits of stems and leaves (i.e. cavitation resistance, water potential, safety margin, vulnerability segmentation, leaf‐sapwood area ratio and water use efficiency) and mortality rates for 130 dominant woody species from six forest types with a range of aridity index in tropical–subtropical China. Our main objectives were to: (1) build a stem‐leaf hydraulic framework and capture the key hydraulic traits, (2) compare the hydraulic strategies of different forest types and functional groups and (3) elucidate the influence of environmental factors and hydraulic traits on mortality rate.Trait network analysis revealed close relationships among stem and leaf hydraulic traits, where cavitation resistance, turgor loss point and P50leaf–stem were the key traits. In general, a larger P50leaf–stem was associated with lower minimum water potential, leaf hydraulic safety margin and leaf‐sapwood area ratio but higher wood density, stem hydraulic safety margin and water use efficiency. Tropical forest (high aridity) had higher leaf embolism resistance, P50leaf–stem, wood density and water use efficiency than subtropical forest (low aridity), while shrubs showed higher leaf embolism resistance and more negative turgor loss point than trees. However, stem‐leaf hydraulic strategy did not differ significantly between evergreens and deciduous. Both aridity index and hydraulic traits affect species mortality. Particularly, P50leaf–stem was a good predictor of drought‐induced mortality in tropical forests.Synthesis. Our results recommend that vulnerability segmentation should be incorporated into the hydraulic strategy of tropical–subtropical woody plants to explore their drought response to future climate change. [ABSTRACT FROM AUTHOR]

Tree microhabitats have been identified as structure-based indicators of biodiversity in temperate forests. However, information on diversity and abundance of these structures are minimal from the tropical regions. To address this, an inventory was conducted to document the distribution pattern of tree microhabitats in the Western Ghats, India. Tree microhabitats belonging to nine categories and 33 sub-categories in the evergreen and moist deciduous habitats were documented and horizontal and vertical distribution patterns were assessed. The evergreen habitat exhibited higher occurrences, with the abundance of injuries at 16.64 ± 6.31 per ha, epiphytes 20.48 ± 12.02 per ha, fungal fruiting bodies 2.68 ± 1.84 per ha, crown deadwood 5.12 ± 2.82 per ha, cavities 6.59 ± 1.37 per ha, growth forms 20.65 ± 3.96 per ha, deadwood 5.94 ± 1.97 per ha, and fresh exudates 0.99 ± 0.46 per ha. In deciduous forests, the abundance of injuries was 10.55 ± 2.95 per ha, epiphytes 6.88 ± 2.01 per ha, fungal fruiting bodies 2.75 ± 1.59 per ha, crown deadwood 6.58 ± 2.79 per ha, cavities 4.2 ± 1.51 per ha, growth forms 6.51 ± 2.19 per ha, deadwood 4.29 ± 1.52 per ha and fresh exudates 0.86 ± 0.96 per ha. Co-occurrence of tree cavities with other tree microhabitats were also presented. Injuries, growth forms, fungal fruiting bodies and deadwood were observed to have strongly correlated with the formation of cavities. [ABSTRACT FROM AUTHOR]

We aimed at an inventory of all populations of wild Phaseolus (bean) species in Costa Rica, in relation to future plant breeding. During the field work in 2003–2018, three new and rare bean species (i.e. P. albicarminus, P. angucianae and P. hygrophilus) were found in different montane forest habitats which originally occupy a small acreage. Field observations, together with satellite images, indicate deforestation due to coffee plantations or pastures. To date only eleven populations of these species are known, distributed along the Talamanca and Fila Cruces mountainous ranges, making them endemic. Their narrow distribution, deforestation affecting the original habitats, and occurrence outside established and enforced protected areas motivate the assessment of their conservation status as 'Endangered' (EN). [ABSTRACT FROM AUTHOR]

Chlorophyllous plants exhibiting partial mycoheterotrophy obtain carbon through mycorrhizal interactions in addition to photosynthesis. In arbuscular mycorrhizal (AM) plants, the Paris‐morphotype (i.e. hyphal coils) is considered essential for mycoheterotrophic carbon gains. Numerous tree species in tropical lowland forests form this morphotype, and under light‐ and nutrient‐limitation, additional carbon gain would be beneficial. However, if seedlings of woody species in the understory of tropical lowland forests exhibit partial mycoheterotrophy remains unexplored.Here we (a) examined the AM morphotype (Paris‐ or Arum‐type) in seedlings of 41 tropical woody species, and (b) to determine if any of the target Paris‐type species are partially mycoheterotrophic, we compared their multi‐element stable isotope natural abundance (13C, 2H, 18O, 15N) with neighbouring autotrophic non‐Paris‐type reference seedlings.About 50% of the investigated species (and 80% of the genera) exhibited the Paris‐type, expanding the number of tropical plant genera with Paris‐type AM. Enrichment in 13C, but not in 18O in target compared with neighbouring reference plants indicated partial mycoheterotrophy in seedlings of 6 of the 21 investigated Paris‐type AM species.Our results indicate for the first time that carbon gain through mycoheterotrophy occurs in seedlings of AM tropical tree species. In tropical forests, partial mycoheterotrophy during seedling establishment may confer so far unrecognised ecological advantages influencing seedling recruitment and ecosystem dynamics. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

We evaluate the effect of some variables related to fruit morphology, tree structure, and forest cover on fruit consumption by birds in the tree species Conostegia xalapensis (Melastomataceae) and Bursera simaruba (Burseraceae), in a semi-humid forest of southern Mexico. Foraging observations were made in 20 trees per species from November 2020 to June 2021. We recorded a total of 18 and 22 bird species consuming the fruits of B. simaruba and C. xalapensis, respectively. Flycatchers preferred fruits of B. simaruba, while thrushes largely consumed fruits of C. xalapensis. For large birds, crop size and foliar height diversity were the most influential variables in the removal of B. simaruba fruits, while small birds were positively correlated with the foliar coverage. For C. xalapensis, forest cover negatively influenced fruit consumption by large birds, while the fruit polar diameter had a positive effect on fruit consumption by small birds. Fruit consumption of C. xalapensis by specialist birds showed a positive relationship with forest cover, while the generalists showed a negative relationship. Decreased fruit removal was observed for B. simaruba by both specialist and generalist birds in forest landscapes. Our results can help understand the drivers of the frugivore-plant relationship in semi-humid tropical forests. [ABSTRACT FROM AUTHOR]

• An automatic burned area mapping algorithm based on active fire data and Sentinel-2 Level 2A imagery is presented. • Good concordance of the proposed algorithm with reference sources. • Global commission errors are higher than omission errors. • Forest fires in tropical and temperate forest are the least accurately mapped ecosystems. • Greater accuracy of the proposed algorithm in comparison to FIRECCI51 and MCD64A1. Understanding the spatial and temporal trends of burned areas (BA) on a global scale offers a comprehensive view of the underlying mechanisms driving fire incidence and its influence on ecosystems and vegetation recovery patterns over extended periods. Such insights are invaluable for modeling fire emissions and the formulation of strategies for post-fire rehabilitation planning. Previous research has provided strong evidence that current global BA products derived from coarse spatial resolution data underestimates global burned areas. Consequently, there is a pressing need for global high-resolution BA products. Here, we present an automatic global burned area mapping algorithm (Sentinel2BAM) based on Sentinel-2 Level-2A imagery combined with Visible Infrared Imaging Radiometer Suite (VIIRS) and Moderate Resolution Imaging Spectrometer (MODIS) active fire data. The algorithm employs a Random Forest Model trained by active fires to predict BA probabilities in each 5-day Normalized Burn Ratio (NBR) index-based temporal composites. In a second step, a time-series and object-based analysis of the estimated BA probabilities allows burned areas to be detected on a quarterly basis. The algorithm was implemented in Google Earth Engine (GEE) and applied to 576 Sentinel-2 tiles corresponding to 2019, distributed globally, to assess its ability to map burned areas across different ecosystems. Two validation sources were employed: 21 EMSR Copernicus Emergency Service perimeters obtained using high spatial resolution (<10 m) data (EMSR21) located in the Mediterranean basin and 50 20x20 km global samples selected by stratified sampling with Sentinel-2 at 10 m spatial resolution (GlobalS50). Additionally, 105 Landsat-based long sample units (GlobalL105), were employed to compare the performance of the Sentinel2BAM algorithm against the FIRECCI51 and MCD64A1 global products. Overall accuracy metrics for the Sentinel2BAM algorithm, derived from validation sources highlight higher commission (CE) than omission (OE) errors (CE=10.3 % and OE=7.6 % when using EMSR21 as reference, CE=18.9 % and OE=9.5 % when using Global S50 as reference), while GlobalL105-based inferenced global comparison metrics show similar patterns (CE=22.5 % and OE=13.4 %). Results indicate differences across ecosystems: forest fires in tropical and temperate biomes exhibit higher CE, mainly due to confusion between burned areas and croplands. According to GlobalL105, Sentinel2BAM shows greater accuracy globally (CE=22.5 %, OE=13.4 %) compared to FIRECCI51 (CE=20.8 %, OE=46.5 %) and MCD64A1 (CE=17.5 %, OE=53.1 %), substantially improving the detection of small fires and thereby reducing omission errors. The strengths and weaknesses of the algorithm are thoroughly addressed, demonstrating its potential for global application. [ABSTRACT FROM AUTHOR]

• A PolInSAR decomposition integrates generalized scattering models. • All model parameters are simultaneously solved using the cross-correlation matrix. • Performance is evaluated with simulated and real PolInSAR data. In this study, a general three-component polarimetric SAR interferometry (PolInSAR) target decomposition framework is proposed by modifying the existing generalized surface, double-bounce, and volume models. The resulting general models are then compared to the original Freeman-Durden modeling strategy. Three types of generalized volume scattering models (generalized volume scattering model (GVSM), simplified Neumann volume scattering model (SNVSM) and simplified adaptive volume scattering model (SAVSM)) were employed. Simulated L-band PolInSAR data over deciduous and pine forest stands generated by PolSARpro and DLR P-band airborne PolInSAR data over a tropical forest area from the AfriSAR 2016 campaign were used for performance analysis. A qualitative comparison of the decomposition results shows that the three generalized volume scattering models generally deviate from the Freeman-Durden model, showing that the GVSM and SNVSM models have very similar results. In the case of airborne data over tropical forests, a tomographic synthetic aperture radar (TomoSAR) profile was also computed and used as a benchmark for comparison with the phase-center profiles of all four volume-scattering components. Not only do the GVSM and SNVSM models exhibit similar results between them (as with simulated data), but also a better match with the HV TomoSAR profile. [ABSTRACT FROM AUTHOR]

Summary: Resource storage is a critical component of plant life history. While the storage of nonstructural carbohydrates in wood has been studied extensively, the multiple functions of mineral nutrient storage have received much less attention. Here, we highlight the size of wood nutrient pools, a primary determinant of whole‐plant nutrient use efficiency, and a substantial fraction of ecosystem nutrient budgets, particularly tropical forests. Wood nutrient concentrations also show exceptional interspecific variation, even among co‐occurring plant species, yet how they align with other plant functional traits and fit into existing trait economic spectra is unclear. We review the chemical forms and location of nutrient pools in bark and sapwood, and the evidence that nutrient remobilization from sapwood is associated with mast reproduction, seasonal leaf flush, and the capacity to resprout following damage. We also emphasize the role wood nutrients are likely to play in determining decomposition rates. Given the magnitude of wood nutrient stocks, and the importance of tissue stoichiometry to forest productivity, a key unresolved question is whether investment in wood nutrients is a relatively fixed trait, or conversely whether under global change plants will adjust nutrient allocation to wood depending on carbon gain and nutrient supply. [ABSTRACT FROM AUTHOR]

Remote sensing can provide continuous spatiotemporal information about vegetation to inform wildlife habitat estimates, but these methods are often limited in availability or lack adequate resolution to capture the three‐dimensional vegetative details critical for understanding habitat. The Global Ecosystem Dynamics Investigation (GEDI) is a spaceborne light detection and ranging system (LiDAR) that has revolutionized the availability of high‐quality three‐dimensional vegetation measurements of the Earth's temperate and tropical forests. To date, wildlife‐related applications of GEDI data or GEDI‐fusion products have been limited to estimate species habitat use, distribution, and diversity. Here, our goal was to expand the use of GEDI‐based applications to wildlife demography by evaluating if GEDI data fusions could aid in characterizing demographic parameters of wildlife. We leveraged a recently published dataset of GEDI‐fusion forest structures and capture–mark–recapture data to estimate the density and survival of two small mammal species, Humboldt's flying squirrel (Glaucomys oregonensis) and Townsend's chipmunk (Neotamias townsendii), from three studies in western Oregon spanning 2014–2021. We used capture histories in Huggins robust design models to estimate apparent annual survival and density as a derived parameter. We found strong support that both flying squirrel and chipmunk density were associated with GEDI‐fusion forest structures of foliage height diversity and plant area volume density in the 5–10 m strata for flying squirrels and proportionately higher plant area volume density in the 0–20 m strata for chipmunks, as well as other spatiotemporal factors such as elevation. We found weak support that apparent annual survival was associated with GEDI‐fusion forest structures for flying squirrels but not for chipmunks. We demonstrate further utility of these methods by creating spatially explicit density maps of both species that could aid management and conservation policies. Our work represents a novel application of GEDI data to evaluate wildlife demography and produce continuous spatially explicit density predictions for these species. We conclude that aspects of small mammal demography can be explained by forest structure as characterized via GEDI data fusions. [ABSTRACT FROM AUTHOR]

Avitourism has multiple conservation and economic benefits but can pose potential harm to some bird populations. To mitigate the potential impacts of avitourism on birds, researchers can use flight initiation distance (FID) to quantify the tolerance of animals to perceived threats, thereby informing management. This study focused on whether clothing colour used by avitourists (orange, camouflage, and black) affected the FIDs of White-rumped Shama Copsychus malabaricus (n = 123) in a protected area in northeastern Thailand. Camouflage clothing evoked significantly shorter FIDs than orange and black clothing, which elicited statistically similar FIDs. The results of this study aligned with the colour concealment hypothesis, which suggests that clothing colour resembling the forest environment reduces detectability, which results in shorter FIDs. As such, clothing colour may mediate disturbance caused by avitourists. Given that at least one species of Southeast Asian tropical forest bird adjusts its FID in relation to clothing colour, FID studies on additional Asian tropical bird species and clothing colours are encouraged. [ABSTRACT FROM AUTHOR]

Plant leaves receive different light intensities that lead to changes in many of their characteristics, including leaf morphology and anatomy. These changes occur in trees within- and between-crown and this ecophysiological issue has been widely addressed in temperate regions. However, due to increased habitat complexity and species richness, tropical forests may create slightly different light gradients. This study compares these gradients using a tropical plant, Eugenia hiemalis, a high plastic shrub. Leaves were collected from the top and base of the crown of sun-exposed plants (within-crown light gradient) and compared with leaves collected from the middle of crowns, of plants in sunny and shaded sites (between-crown light gradient). The analysis of 25 morphological and anatomical characteristics showed that the between-crown light gradient has a greater influence on leaf responses to light, possibly due to the existence of highly shaded environments in tropical forests compared to surrounding grasslands. Leaves that receive more light have a thicker cuticle and mesophyll and higher stomatal density, leaves at the top of the crown. On the other hand, leaves at the base of the crown and from shaded sites had greater leaf area, leaf dry mass, and specific leaf area. The vertical light gradient that occurs within-crown is weaker than the between-crown gradient, suggesting a great acclimation ability of species both inside and outside tropical forests, such as found in E. hiemalis. [ABSTRACT FROM AUTHOR]

In tropical disturbed forests, it is relatively unknown the extent insect communities are experiencing shifts in species diversity and the consequences for ecosystem functions and services. In southern Mexico, we used the rove beetle community associated to Heliconia wagneriana bracts, as a model system, to investigate differences in community attributes and feeding habits between old-growth and human induced secondary forests. We tested if the beta diversity components of rove beetle communities were influenced by forest type and bract traits. Furthermore, we described the topology of individual-based heliconia-rove beetle ecological networks. Overall, we recorded 26 rove beetle species with significantly greater abundance in secondary forests. High compositional dissimilarity between forest types was observed with saprophagous species being more likely detected in old-growth forests; whereas predatory species in secondary forests. Heliconia-rove beetle networks showed a significant nested pattern with incidence data for old-growth forests and incidence and abundance data for secondary forests. Compared to old-growth forests, the rove beetle community in secondary forests showed strong shifts in species composition, diversity and differences in the detection probability of feeding habits, with consequences for ecosystem functioning. We further discuss these findings according to the forest disturbance and phytotelm systems. Implications for insect conservation: Individuals of H. wagneriana represent biodiversity reservoirs for invertebrates, especially in human-modified landscapes. [ABSTRACT FROM AUTHOR]

Many allometric models to predict tree aboveground biomass have been developed in tropical moist forests, but few models are available for tree belowground biomass. Theory predicts that belowground biomass scales in an isometric way with aboveground biomass. Estimates of belowground biomass could then be derived from aboveground biomass using the root:shoot ratio. Using a dataset of 118 tropical trees for which both aboveground and belowground biomass and other tree and species characteristics were measured in Gabon and Cameroon, we found a near isometric, yet significantly allometric, relationship between belowground biomass (B , in kilograms) and aboveground biomass (A , in kilograms): B  = 0.324 A 0.939. The root:shoot ratio was 0.20–0.22, regardless of tree size. An efficient model to predict belowground biomass from tree diameter (D , in centimeters), height (H , in meters) and wood density (ρ, in grams per cubic centimeter) was B  = 0.0188 (ρ D 2 H)0.977. A significant residual effect of species and leaf habit was found in this model, indicating that further tree and species characteristics are likely to explain additional variation in belowground biomass. Yet, the future development of belowground allometric models can benefit from the many models already developed for aboveground biomass. On the basis of this unprecedented sampling effort on tree belowground biomass in the dense tropical forests of the Congo Basin, we conclude that the scaling of belowground biomass with aboveground biomass should be the relationship to focus on. [ABSTRACT FROM AUTHOR]

Forests are essential for the ecological functioning providing critical habitats for biodiversity and hold large biomass, which are affected by bioclimatic and topographical variables. This study investigated the topographic factor (elevation) that play an important role in forest diversity and biomass distribution. The present study examined the relationship between topographical (viz. elevation, slope, aspects) and Bioclimatic variables (temperature/ precipitation) with measured biomass of Tropical forests. The study area selected is Sariska Tiger Reserve (STR), a tropical forest with high conservation priorities with fewer disturbances. Earth observation datasets such as ALOS-PALSAR, SRTM, and GEDI aboveground biomass density (AGBD) are retrieved in the Cloud computing platform (GGE) to generate outcomes. The study also utilized Bioclimatic variables such as maximum, minimum and mean temperature during warmest/coldest month and warmest, coldest, wettest, driest Quarters. GEDI derived mean biomass was observed to be 1.3 to 95 Mg/ha ± (0.68–5.88 SD). The data was statistically analyzed using correlation coefficient (R) for topographic and bioclimatic variables. Results specified six Biodiversity indices (BDI), and six bioclimatic variables during analysis. Correlation coefficient (R) indicated strong positive relationship of three biodiversity indices with elevation for Shannon - Weiner index (R = 0.71) followed by Margalef richness index (R = 0.65) and reciprocal Simpson index (R = 0.61). While Buzas and Gibson Index (R=−0.45), Berger dominance index (R=−0.27), and Menhinick index (R=−0.51) showed negative correlation with elevation. Overall, topographic and bioclimatic variables are governed by elevation for biomass and carbon stocks (with r=−0.41). Similarly, correlation coefficient (R) of elevation against max temperature during Warmest month (MTMW), Warmest Quarter (MTWarQ) and Wettest Quarter (MTWetQ) indicated strong negative correlation with R value of −0.88, −0.88, and − 0.87 respectivelry. It is followed by MTColdest Quarter (R=−0.85) and MinTCM (R=−0.84). while lowest correlation was shown by Min Temp during Driest Quarter with R=−0.23. Outcomes showed declining trends of biomass stocks ranged from 129.44 mg/t to 7.07 mg/t with significantly increasing trends till mid elevation and thereafter decreasing trends of tree biomass with increasing elevation. Highest biomass of 95 mg/t (GEDI derived) and Field measured Biomass of 129.44 mg/t was observed at intermediate elevation of 530 m after that showed decline in biomass distribution. Elevation can act as a dominant determinant for AGB in tropical forest for several reasons, such as topographic variations, temperature variations, precipitation patterns, soil nutrient availability, species adaptation, disturbance regimes, and most influencing one is human activities. Therefore, elevation can be a crucial predictor in conjunction with other factors to influence biomass at undisturbed places with high slopes and controlled species richness, distribution and biomass accumulation in tree species. Highlights: 1. Elevation effects species distribution and richness (in conjunction with bioclimatic factors). 2. Highest biomass of 95 mg/t (GEDI derived) and Field measured Biomass of 129.44 mg/t was observed at intermediate elevation of 530 m after that declining trend in biomass distribution (elevation ranges from 262 m to 721m). 3. Topographical and Bioclimatic variables' relationship against biomass and biodiversity index. 4. Cloud computing applications (GGE) provide datasets for fast analysis and outcomes for local and global scales. [ABSTRACT FROM AUTHOR]

Societal Impact Statement Summary Contemporary land use studies often place food production in direct conflict with tropical forests, with forest land use for human needs exiting in conflict with carbon‐related forest conservation and biodiversity protection efforts. We highlight the more nuanced, mixed activities possible in the space between primary forest and fixed, monocultures that were, and are, practiced by Indigenous communities from the deep past into the present. Given the increasingly clear importance of the tropics to human history and contemporary human sustainability, this work has key implications for understanding past human‐environment processes, empowering Indigenous stewardship and informing forest conservation policy. Tropical forests are key components of the global carbon cycle given their considerable carbon stocks. Agriculture is often seen as in major conflict with tropical forests, with carbon budget models highlighting dramatic carbon stock losses with the conversion of land for food. However, these models often focus on monocultural cropping systems, while the archaeological and historical records highlight more varied forms of food production in tropical forests from at least 8,000 years ago. Here we develop a simple model to simulate relative aboveground carbon (AGC) values for a tropical forest anthrome with varied food production practices. We examine past examples of tropical land use activities including understory thinning, selective agroforestry and various swidden patterns. We compare these to old‐growth forests, open cropping and plantation systems. Results highlight the importance of retaining large trees to AGC. Understory thinning practices have a limited effect on AGC by mainly impacting small trees. Regular, short fallow swidden drastically reduces AGC, while irregular, long fallow swidden can maintain AGC half that of old growth forest. A mosaic landscape of forest food production can maintain much higher long‐term mean AGC values than is typically assumed for carbon budgets of past land use. [ABSTRACT FROM AUTHOR]

Resource partitioning among sympatric species is crucial for assembling ecological communities, such as caterpillar–ant assemblages in tropical forests. Myrmecophilous caterpillars use behavioral and chemical strategies to coexist with ants, avoiding attacks. While these strategies are well‐understood in single pair of interacting species, such as those involving myrmecophiles and ants, their role in complex multitrophic interactions that include several species of plants, herbivores and ants remains unclear. We aimed to identify the role of cuticular hydrocarbons and specialized morphological structures that caterpillars use to interact with ants (called ant organs) in the recognition process between two riodinid caterpillar species and their respective ant–plant systems. We hypothesized that caterpillars’ cuticular profiles would be conspicuous, possessing cues of rewards to ants, allowing specific ants to recognize and not attack them on plants. We performed experiments exposing caterpillars to ants to assess the role of larval ant organs and the specificity of caterpillar–ant interactions on plants. We analyzed cuticular hydrocarbons of caterpillars, ant workers and plants using gas chromatography/mass spectrometry. Our experiments showed that larval ant organs were activated according to each treatment and caterpillars were consistently accepted by their associated ants when transferred to host plants occupied by the same ant species. However, caterpillars transferred to plants with a non‐associated ant species that do not tend them were often killed. This highlights the specificity of these interactions. Caterpillar cuticular hydrocarbon profiles, while present in far lower amounts than those of ant workers and plants, were distinctive, suggesting a strategy of chemical conspicuousness that helps caterpillars to be recognized by ants and prevents attacks in specific ant–plant systems. Our results indicate that ants recognize conspicuous cuticular hydrocarbons, while caterpillars convey multimodal signals from ant organs during interactions, which are essential for caterpillar survival in these specific interactions. [ABSTRACT FROM AUTHOR]

Tree successional diversity is evident even to casual observers and has a well-understood physiological basis. Various life history trade-offs, driven by interspecific variation in a single trait, help maintain this diversity. Conspecific negative density dependence (CNDD) is also well-documented and reduces tree vital rates independently of succession strategies. The CNDD hypothesis is frequently justified by specialist natural enemies at a separate trophic level. We integrate these processes into an analytical demographic model, spanning short-term plant physiological responses to the dynamics of a large forest mosaic connected to a metacommunity. Surprisingly, multiple trade-offs do not necessarily increase diversity, as suboptimal trait combinations lead to strategies that cannot compete for successional niches, explaining the weak correlation between functional traits and succession position. Succession alone can sustain half of the species in the metacommunity, with diversity increasing linearly with CNDD strength. The steeper increase with larger metacommunities suggests CNDD plays a greater role in tropical forests. However, if each successional type contains multiple equivalent species, CNDD maintains diversity but becomes less effective in promoting successional diversity, consistent with some tropical forests being less successional diverse. Additionally, CNDD enhances the likelihood of successful speciation and shifts life-history trait frequency by affecting more late-successional species. The study introduces an analytical forest diversity model that integrates gap-phase successional dynamics, conspecific negative density dependence (e.g., natural enemies), and evolutionary processes, connecting the forest mosaic to a metacommunity. [ABSTRACT FROM AUTHOR]

ABSTRACT Understanding mechanisms driving tropical tree growth is essential for comprehending carbon sequestration and predicting the future of tropical forests amid rapid deforestation. We conducted a natural experiment in Mount Cameroon to identify climatic factors limiting diurnal and seasonal growth in dominant tree species across a 2200‐m elevation gradient, from lowland rainforests to montane mist forests with distinct wet and dry seasons. Using high‐precision automatic dendrometers, we recorded radial growth rates of 28 tropical tree species from 2015 to 2018, correlating them with rainfall (11 100–2500 mm) and temperatures (23–14°C) across elevations. Significant growth limitations were suggested at both extremes of water availability. Tree growth peaked during the dry and prewet seasons at humid lower elevations and during wet seasons at drier higher elevations. Growth rates increased with soil moisture at higher elevations and peaked at medium soil moisture at lower elevations. Trees grew fastest at lower temperatures relative to their elevation‐specific means, with growth limited by high daytime temperatures and promoted by nighttime temperatures. Our results revealed significant interspecific diurnal and seasonal growth variations hindered by both water scarcity and excess in West African rainforests, essential for forecasting and modelling carbon sinks. [ABSTRACT FROM AUTHOR]

Summary Leaf dark respiration (Rdark), an important yet rarely quantified component of carbon cycling in forest ecosystems, is often simulated from leaf traits such as the maximum carboxylation capacity (Vcmax), leaf mass per area (LMA), nitrogen (N) and phosphorus (P) concentrations, in terrestrial biosphere models. However, the validity of these relationships across forest types remains to be thoroughly assessed. Here, we analyzed Rdark variability and its associations with Vcmax and other leaf traits across three temperate, subtropical and tropical forests in China, evaluating the effectiveness of leaf spectroscopy as a superior monitoring alternative. We found that leaf magnesium and calcium concentrations were more significant in explaining cross‐site Rdark than commonly used traits like LMA, N and P concentrations, but univariate trait–Rdark relationships were always weak (r2 ≤ 0.15) and forest‐specific. Although multivariate relationships of leaf traits improved the model performance, leaf spectroscopy outperformed trait–Rdark relationships, accurately predicted cross‐site Rdark (r2 = 0.65) and pinpointed the factors contributing to Rdark variability. Our findings reveal a few novel traits with greater cross‐site scalability regarding Rdark, challenging the use of empirical trait–Rdark relationships in process models and emphasize the potential of leaf spectroscopy as a promising alternative for estimating Rdark, which could ultimately improve process modeling of terrestrial plant respiration. [ABSTRACT FROM AUTHOR]

There is still a lack of practical guidelines for understanding species roles and planning restoration strategies to enhance plant–pollinator interactions and support ecosystem functioning. We applied a network approach to understand the evolution of plant–pollinator restoration patterns and identify priority species, thus advancing restoration planning. Specifically, we compared species composition and network metrics along a gradient of time postdisturbance, from the initial stage of restoration to pristine forest in the Eastern Amazon. We found that mining type is a predictor of species composition. We observed the recovery of interaction diversity and pollinator specialization in the early stages of restoration. Mining type affected connectance, interactions, and species richness, and the restoration stage affected the number of links. From the interactions, we built a trait‐based framework to select manageable native species for initial restoration. The species selection framework proposed here is useful not only for forest restoration but also for the restoration of other areas and case studies (e.g. agroecosystems, conservation units, and ecological corridors) and can be adapted depending on the goals of each project. Here, we provide practical information for the management of mined land restoration in the Eastern Amazon and for restoration planning across broader scales. [ABSTRACT FROM AUTHOR]

We describe two new caecilian species of the genus Caecilia (Gymnophiona: Caeciliidae) from the wet tropical Chocó Forest, north-western Ecuador. We applied an integrative taxonomic approach, taking into consideration external morphology, osteology from intensive ct-scanning, and molecular phylogenetic analyses. The two new species were compared to all other Caecilia species, known to occur west of the Ecuadorian and Colombian Andes. The new taxa can be distinguished by their external morphological characters, as well as by their osteology, genetic divergence, and phylogenetic relationships. The two new species, although morphologically quite different, were closely related. Caecilia tesoro sp. n. is a large-bodied, robust species with a unique colour pattern in larger individuals. In contrast, Caecilia truncata sp. n. is a smaller caeciliid and sister to medium-sized C. volcani, a species known from Panama. Morphologically, C. truncata sp. n. is best recognized by a very truncated snout shape. As know from many previously recognized neotropical caeciliids, both new species are likely endemic to small ranges, here the humid tropical lowland to mid-altitude forests of western Ecuador. Both new species seem to tolerate some degree of habitat degradation. Our new findings support to intensify research and conservation activities in one of South America's most diverse but severely endangered biomes. We also present, for the first time, some clues of the phylogenetic position of elongated C. nigricans and C. leucocephala. Caecilia nigricans was sister to a clade composed of one Oscaecilia and ten species of Caecilia. This topology rendered the genus Caecilia paraphyletic relative to Oscaecilia. [ABSTRACT FROM AUTHOR]

Premise Methods Results Conclusions The soils in lowland tropics are teeming with microbial life, which can impact plant community structure and diversity through plant–soil feedbacks. While bacteria and fungi have been the focus of most studies in the tropics, oomycetes may have an outsized effect on seed and seedling health and survival, given their affinity for moister, warmer environments.We assessed the diversity and pathogenicity of oomycete species present in a lowland tropical forest in Panama. We used a culture‐dependent leaf‐baiting assay and culture‐independent soil DNA metabarcoding methods to quantify zoospore abundance and species diversity. A subset of the isolates from the baiting assay were used to evaluate pathogenicity and symptom severity on seedlings of three tree species.Oomycetes were ubiquitous and common members of the soil microbial community in lowland tropical forests, and zoospore abundance was far greater compared to similar studies from temperate and mediterranean forests. The various oomycete species also varied in the ability to infect host plants. Species of Pythium were more virulent, while species of Phytopythium caused less severe symptoms but were more diverse and commonly isolated from the soil. Finally, we found that individual hosts accumulated a distinct oomycete community and was the only factor that had an effect on community structure.Collectively, these findings demonstrate that oomycetes are ubiquitous, host‐generalist pathogens and saprophytes, that can impact seed and seedling survival in lowland tropical forests. [ABSTRACT FROM AUTHOR]

The forests of the Amazon basin are threatened by climate and land use changes. Due to the transition towards a drier climate, moisture-dependent organisms such as canopy epiphytes are particularly affected. Even if the topography in the Amazon lowland is moderate, mesoscale nocturnal katabatic flows result from cold air production related to radiative cooling. From a certain level of mass the cold air starts to flow downslope towards the valley centers leading to temperature inversions. The resulting cooling in the valleys drives localized fog formation in the valleys at night. This correlates with high epiphyte abundance and diversity in the valleys, which is much less pronounced upslope. The underlying temperature dynamics are, however, not sufficiently included in coarse-resolution reanalysis models such as ERA5-Land. Since high resolution climate data are needed e.g. for proper niche modeling of locally distributed species such as canopy epiphytes, downscaling models such as microclima have been developed and include micro- and mesoscale effects. However, it is unclear how well the elevation-related diurnal course of air temperature can be simulated. Here, we test functions for downscaling coarse-resolution temperature data to high spatial resolution data implemented in the R-package microclima for the South American tropical lowland forests. To do so we compared microclima-downscaled ERA5-Land air temperature data with meteorological station data. We found that the microclima functions only properly detect 73 temperature inversions out of 412 nocturnal cold air drainage (CAD) events during the dry season study period and only 18 out of 400 during the wet season with default settings. By modifying default values such as the emissivity threshold and time frames of possible CAD condition detection, we found 345 of 412 CAD events during the dry season and 177 out of 400 during the wet season. Despite problems with the distinction between CAD and non-CAD events the microclima algorithms show difficulties in correctly modeling the diurnal course of the temperature data and the amplitudes of elevational temperature gradients. For future studies focusing on temperature downscaling approaches, the modules implemented in the microclima package have to be adjusted for their usage in tropical lowland forest studies and beyond. [ABSTRACT FROM AUTHOR]

Tropical forests dominate terrestrial photosynthesis, yet there are major contradictions in our understanding due to a lack of field studies, especially outside the tropical Americas. A recent field study indicated that West African forests have among the highest forests gross primary productivity (GPP) yet observed, contradicting models that rank them lower than Amazonian forests. Here, we show possible reasons for this data-model mismatch. We found that biometric GPP measurements are on average 56.3% higher than multiple global GPP products at the study sites. The underestimation of GPP largely disappears when a standard photosynthesis model is informed by local field-measured values of (a) fractional absorbed photosynthetic radiation (fAPAR), and (b) photosynthetic traits. Remote sensing products systematically underestimate fAPAR (33.9% on average at study sites) due to cloud contamination issues. The study highlights the potential widespread underestimation of tropical forests GPP and carbon cycling and hints at the ways forward for model and input data improvement. This study finds that vegetation models commonly underestimate the productivity of West African forests, owing to bias in fractional absorbed photosynthetic radiation (fAPAR) and leaf level photosynthetic capacities. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Sexual selection, one of the central pillars of evolutionary theory, has powerful effects on organismal morphology, behaviour, and population dynamics. However, current knowledge about geographical variation in this evolutionary mechanism and its underlying drivers remains highly incomplete, in part because standardised data on the strength of sexual selection is sparse even for well-studied organisms. Here, we use information on mating systems—including the incidence of polygamy and extra-pair paternity—to estimate the intensity of sexual selection in 10,671 (>99.9%) bird species distributed worldwide. We show that avian sexual selection varies latitudinally, peaking at higher latitudes, although the gradient is reversed in the world's most sexually selected birds—specialist frugivores—which are strongly associated with tropical forests. Phylogenetic models further reveal that the strength of sexual selection is explained by temperature seasonality coupled with a suite of climate-associated factors, including migration, diet, and territoriality. Overall, these analyses suggest that climatic conditions leading to short, intense breeding seasons, or highly abundant and patchy food resources, increase the potential for polygamy in birds, driving latitudinal gradients in sexual selection. Our findings help to resolve longstanding debates about spatial variation in evolutionary mechanisms linked to reproductive biology and also provide a comprehensive species-level data set for further studies of selection and phenotypic evolution in the context of global climatic change. Sexual selection has powerful effects on organismal morphology, behavior and population dynamics, but how does it vary geographically, and what are the underlying drivers? This study of 10,671 bird species distributed worldwide reveals that avian sexual selection varies latitudinally, and is explained by temperature seasonality coupled with a suite of climate-associated factors. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Tropical biodiversity is undergoing unprecedented changes due to the hydrological cycle intensification, characterized by more intense droughts and wet seasons. This raises concerns about the resilience of animal and plant communities to such extremes and the existence of potential refugia—areas theorized to safeguard biological communities from adverse climate impacts. Over 20 years of monitoring in Central Amazonia, we investigated the short‐term and long‐term effects of hydrological cycle intensification on bird, fish, ant, and palm communities. We explored whether the 'insurance effect' of climate trends (droughts buffered by preceded wet seasons) or 'environmental refugia' (droughts or floods buffered by topographic features) could lessen the impact of climate events on community composition, richness, evenness, and species rank. Pronounced abundance changes were observed among animal species, whereas palm species showed relative temporal stability. Birds and fish were more affected by the immediate and long‐term severity of droughts and wet periods, while ants responded primarily to short‐term drought impacts. Conversely, palm communities exhibited delayed responses to climate extremes, primarily in long‐term comparisons. As expected, the proposed 'insurance effect' mitigates the long‐term impacts of extreme climate events on animal and plant community trends. However, less extreme hydrological conditions linked to topographic features did not provide effective 'environmental refugia' for animals or plants during adverse climate conditions. These outcomes underscore the complex and varied biological responses to ongoing climate change, challenging the prevailing assumptions about the efficacy of environmental refugia and highlighting the nuanced resilience of biodiversity in Central Amazonia. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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

The forests and grasslands in the U.S. are vulnerable to global warming and extreme weather events. Current satellites do not provide historical vegetation density images over the long term (more than 50 years), which has restricted the documentation of key ecological processes and their resultant responses over decades due to the absence of large-scale and long-term monitoring studies. We performed point-by-point regression and collected data from 391 tree-ring plots to reconstruct the annual normalized difference vegetation index (NDVI) time-series maps for the contiguous U.S. from 1850 to 2010. Among three machine learning approaches for regressions—Support Vector Machine (SVM), General Regression Neural Network (GRNN), and Random Forest (RF)—we chose GRNN regression to simulate the annual NDVI with lowest Root Mean Square Error (RMSE) and highest adjusted R2. From the Little Ice Age to the present, the NDVI increased by 6.73% across the contiguous U.S., except during some extreme events such as the Dust Bowl drought, during which the averaged NDVI decreased, particularly in New Mexico. The NDVI trend was positive in the Northern Forest, Tropical Humid Forest, Northern West Forest Mountains, Marin West Coast Forests, and Mediterranean California, while other ecoregions showed a negative trend. At the state level, Washington and Louisiana had significantly positive correlations with temperature (p < 0.05). Washington had a significantly negative correlation with precipitation (p < 0.05), whereas Oklahoma had a significantly positive correlation (p < 0.05) with precipitation. This study provides insights into the spatial distribution of paleo-vegetation and its climate drivers. This study is the first to attempt a national-scale reconstruction of the NDVI over such a long period (151 years) using tree rings and machine learning. [ABSTRACT FROM AUTHOR]

The purpose of this study is to characterize the pool of lignin phenols in soils of two contrasting secondary forest ecosystems—boreal and tropical—with different tree species and to assess the rate of biochemical transformation of difficult-to-degrade compounds of lignocelluloses nature in them. A detailed and comparative description of the biochemistry of lignin in soils in experiments on artificial afforestation in Krasnoyarsk krai of Russia (Greyzemic Phaeozems (Albic)) and in the Amazon Region, Brazil (Xanthic Ferralsol) is presented. Determination of lignin in soils involved alkaline oxidation with copper oxide at 170°C under pressure in a nitrogen atmosphere. Lignin phenols (vanillin, syringyl, and cinnamyl) were separated, using gas chromatography. It has been shown that lignin mineralization is rapid in soils of both boreal and tropical secondary forests contrary to soils of natural zonal ecosystems. A significant enrichment of lignin with metabolic carbon is a characteristic feature of this process. Low content, high oxidation rate, and a high degree of transformation of lignin are typical for soils of all the studied secondary forests, for tropical ones in particular, which reduces their potential as carbon sink reservoirs versus taiga soils. [ABSTRACT FROM AUTHOR]

Extreme heat events are becoming increasingly common, and the short‐term acclimation of photosynthesis will have a large impact on plant performance. Trees in lowland tropical forests, which are hypothesized to have limited abilities to tolerate rising temperatures, may need to rely on short‐term acclimation of their more plastic traits, like photosynthetic thermal tolerance, to persist in the face of increasingly variable climates.Here, we investigated seasonal acclimation of thermal tolerances in plant species of the moist Amazon. Specifically, we measured the photosynthetic thermal tolerances of six common woody Amazonian species at the beginning and at the end of the dry season to determine the species' abilities to acclimate to intra‐annual changes to climate. In addition, we used the natural thermal gradient present at our research site to test the acclimation of individual plants to maximum air temperatures not currently observed elsewhere in the moist lowland Amazon (up to ~43°C).Between seasons, there were significant overall increases in the thermal tolerances of three species (i.e. higher thermal tolerances in the hotter dry season), suggesting that leaf megathermy is prominent in these species. Also, three species acclimated their thermal tolerances to microsite‐level differences in seasonal temperature maxima, suggesting closer fidelity between leaf and air temperatures (i.e. limited homeothermy) for these species.Our results show that some woody species from the moist Amazon can acclimate their thermal tolerances over short time‐scales, although acclimation is likely insufficient to overcome thermal stress during extreme temperature events. Some species may therefore be more sensitive to heatwaves than others, which could impact survival and composition of tropical lowland forests into the future. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Decreasing returns in resource acquisition ability with increasing leaf mass investment is called 'diminishing returns', which provides important insights into plant economy. Yet, whether this is true for fine roots and how root resource acquisition strategies change with forest succession remain unclear.We investigated the scaling relationship between fine‐root length (L) and mass (M) for 215 topsoil cores from 24 plots across four successional stages in tropical forests of Xishuangbanna, southwestern China. We also assessed the relative effects of edaphic conditions, leaf functional traits, tree species diversity and soil fungal factors on L versus M scaling relationship using hierarchical variation partitioning.Our results revealed the existence of diminishing returns in root length (L vs. M scaling exponent <1), and that the exponent was higher in late‐ than early‐successional forests, corresponding to a strategy shifting from 'do‐it‐yourself' in the late‐successional stage to 'outsourcing' resource uptake by soil fungi in the early‐successional stage. Soil fungal abundance was the main driver of changes in the L versus M scaling exponent across plots (explained 58% of variances), with root endophytic fungi the strongest predictor (22.11%), followed by mycorrhizal fungi (10.41%), while other factors (leaf functional traits, edaphic nutrient conditions and tree species diversity) exerted weak effects.Our results suggest that root endophytic and mycorrhizal fungi act as key modulators of root economy changes during forest succession, but the former has received less attention previously. L versus M scaling exponent may be a better indicator for shifts in root resource acquisition strategy than the commonly used specific root length. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Tropical forest understories tend to be light‐limited. The red‐to‐far‐red ratio (R:FR) is a useful and reliable index of light quality and its spatial variability can influence competition between native and non‐native seedlings. While per cent light transmittance has been quantified in some Hawaiian lowland wet forests (HLWF), no information exists on how the spatial distribution of understorey light varies in relation to species invasion, or if patterns of seedling regeneration and light are linked.We measured the R:FR of light in the understorey to assess light quality in three HLWF forest types: native‐dominated, partially invaded and Psidium cattleyanum‐ (strawberry guava) dominated to quantify light quality in the understorey (0–50 cm height). We also identified relationships between light quality and native and non‐native seedling presence, diversity and abundance. Together, these data can help to determine the restoration potential of HLWF.Linear mixed‐effect modelling showed that native‐dominated forests had significantly greater R:FR than P. cattleyanum‐dominated forests, demonstrating a transformation in the light environment with increased invasion. Heterogeneity in R:FR varied more across sites than among forest types. In both native‐dominated and partially invaded forests, there were more native seedlings in the low‐quality R:FR (0.0–0.40) category and fewer in the medium‐ (0.41–0.70), and high‐quality (≥0.71) light categories than would be expected by chance, and there were no native seedlings in the P. cattleyanum‐dominated forests.Native‐dominated forests had greater species richness and abundance of native seedlings than the partially invaded forests, likely due to propagule availability. However, the spatial clustering of seedlings, the mismatch of native seedlings in light environments less suitable, and a considerable proportion of open high‐quality microsites, highlights that conditions are not optimal for native species in HLWF in the long term.Synthesis and applications. The native‐dominated and partially invaded forests still hold conservation value, despite variation among sites. Seedling additions could be targeted to different R:FR environments and at different spatial scales, but the lack of a strong relationship between R:FR and seedling number suggests that other factors besides light quality should be considered in seedling enrichment or other management activities. [ABSTRACT FROM AUTHOR]

Canopy gaps are widely recognized as being crucial for maintaining the diversity of forest tree communities. But empirical studies have found mixed results because the differences in diversity between individual gaps and non‐gaps are often small and statistically undetectable. One overlooked factor, however, is how small individual gap versus non‐gap differences may accumulate across sites and potentially have a large effect on forest diversity at the plot scale. Our study investigated sapling richness, density, and composition in 124 treefall gaps, and 200 non‐gap sites in the 50‐ha tropical forest plot at Barro Colorado Island (BCI), Panama. Additionally, we analyzed species accumulation curves to understand how species richness increases with increasing stem numbers. We observed that sapling richness and density were only slightly higher in gaps 7 years after formation and statistically indistinguishable from non‐gaps after 12 years. However, species accumulation curves across multiple gaps were substantially higher than those across non‐gaps. Species composition showed small differences between individual gaps and non‐gaps but differed significantly between collections of gaps and non‐gaps. Specifically, 55 species specialized in 7‐year‐old gaps compared with 24 in non‐gaps; of these, 23 gap‐specialized species and zero non‐gap species were pioneers. Our results indicate that tree species richness is higher in gaps because of both higher stem density and the presence of gap‐specialized species. Our study has finally provided compelling evidence to support the idea that gaps enhance the overall diversity of tropical forest tree communities. [ABSTRACT FROM AUTHOR]

Insectivorous predators, including birds and bats, play crucial roles in trophic cascades. However, previous research on these cascades has often relied on permanent predator exclosures, which prevent the isolation of specific effects of birds and bats, given their different activity patterns throughout the day. Moreover, limited knowledge exists regarding the variations in individual effects of these predators under different biotic and abiotic conditions, such as changes in elevation. To address these uncertainties, our study aimed to investigate the distinct effects of bats and birds on arthropod densities in foliage and herbivory damage in lowland and highland rainforests of Papua New Guinea (PNG). Predator exclosures were established for one month to exclude diurnal or nocturnal predators across 120 saplings (ca. 2.5–4 m tall) selected from two lowland and two highland forests (i.e., 30 saplings per study site) along the Mt. Wilhelm transect in PNG. Arthropods were collected and measured, and herbivory damage was analyzed at the end of the experiment. Birds significantly reduced arthropod densities by 30%, particularly in arthropods longer than 10 mm, regardless of elevation. Additionally, both birds and bats appeared to mitigate herbivory damage in highland forests, with protected saplings displaying up to 189% more herbivory. Our results support previous studies that have demonstrated the ability of insectivorous predators to reduce leaf damage through the control of arthropods. Furthermore, our approach highlights the importance and necessity of further research on the role of seasons and elevations in trophic cascades. [ABSTRACT FROM AUTHOR]

Bamboos are perennial woody grasses that display an enigmatic mix of traits. Bamboo is highly shade intolerant like early‐successional trees. Without secondary xylem, bamboos cannot continue to grow once they reach a maximum height or replace xylem damaged by hydraulic stress and must instead replace each stem after a few years using vegetative propagation via rhizomes. These traits of bamboo would appear to make them inferior to trees in competition for both light and water in all but early‐successional wet locations. However, some species competitively exclude trees and form persistent monodominant stands across large areas in tropical and temperate forests, including areas that are not mesic. Moreover, bamboo paradoxically postpones seed production for decades to over a century, and then flowers semelparously and dies synchronously. The delayed reproduction appears to be inconsistent with an early‐successional strategy to colonize disturbed areas as soon as they form, while the simultaneous death over large areas appears to be inconsistent with a late‐successional strategy to gain and hold space. Bamboo exhibits great diversity in its growth form and life histories along the tropical‐temperate geographical cline, with tropical bamboo being taller with shorter rhizome lengths and flowering interval lengths than temperate bamboo. We hypothesize that all of the above characteristics of bamboo are essential elements of competitive strategies to arrest succession in a lineage that lacks secondary xylem. To develop this Arrested Succession Hypothesis, we construct mathematical models of competition for recently disturbed areas between a tree species and a species with bamboo's enigmatic characteristics. We modeled the growth of bamboo genetic individuals from seedlings after seed germination to clonal culms at mass flowering and then placed these individuals in competition with one another and with trees in simple models of competition for light. Results explain how bamboo's traits allow it to persist in forests late in succession despite its hydraulic disadvantages, and form monodominant stands in the temperate zone, but not in tropical forests. They explain why bamboo is semelparous with synchronized reproduction, and why maximum culm size and age, reproductive interval, and rhizome length differ between the tropics and the temperate zone. [ABSTRACT FROM AUTHOR]

The composition of plant functional traits varies in response to environmental conditions due to processes of community assembly and species sorting. However, there is a lack of understanding of how plant trait composition responds to environmental conditions at different spatial scales and across the plant life cycle. We investigated the trait composition of leaves (specific leaf area), seeds (seed mass) and seedlings (initial seedling height) across elevations and within elevations in relation to soil and light conditions in a tropical montane forest in southern Ecuador. We surveyed traits and communities of adult trees, seeds and seedlings on nine plots at three elevations (1000–3000 m a.s.l.) and calculated community‐weighted mean trait values to analyse trait variation across and within elevations. In addition, we measured two environmental factors (soil C/N ratio and canopy openness) to quantify local‐scale variation in environmental conditions within elevations. We found that community‐weighted means of specific leaf area, seed mass and initial seedling height decreased consistently with increasing elevation. Within elevations, mean trait values of trees, seeds and seedlings responded differently to local‐scale environmental conditions. Specific leaf area decreased with increasing soil C/N ratio, and initial seedling height decreased with increasing canopy openness. Seed mass was associated neither with soil nor with light conditions. Our findings show that broad‐scale and local‐scale processes differently shape the composition of leaf, seed and seedling traits in tropical forests, indicating a scale‐dependence in trait–environment associations. Furthermore, plant traits corresponding to different life stages were related differently to environmental conditions within elevations. Community assembly processes may therefore lead to differences in species sorting at early and late plant life stages. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)