Search Results (399)

Accurate biomass and carbon estimation in tropical plantation forests requires species-specific allometric models. Silver Oak (Grevillea robusta A. Cunn. ex R. Br.), cultivar “AVAONE,” is widely planted in northeastern Thailand, yet locally calibrated equations remain limited. This study developed species- and site-specific allometric models using destructive sampling of eight trees (n = 8) aged 2–9 years from a single plantation in Pak Chong District, Nakhon Ratchasima Province, without independent validation. Each tree was separated into stem, branches, leaves, and roots to determine fresh and dry biomass, and carbon concentrations were measured using a LECO CHN628 analyzer in an ISO/IEC 17025-accredited laboratory. Aboveground biomass increased from 17.49 kg at age 2 to 860.42 kg at age 9, with the most rapid gains occurring between ages 6 and 9. Tree height stabilized at approximately 19–20 m after age 7, while diameter continued to increase. Stems accounted for the largest proportion of dry biomass, followed by branches and roots. Carbon concentrations ranged from 45.561% to 48.704%, close to the IPCC default value of 47%. Power-law models based on D²H showed clear relationships with biomass, with R² values ranging from 0.7365 to 0.9372 for individual components and 0.8409 for aboveground biomass. These locally derived equations provide preliminary, site-specific relationships for estimating biomass and carbon stocks in Silver Oak AVAONE plantations and offer a baseline for future studies with expanded sampling and independent validation. Full article

Unmitigated climate change, coupled with habitat loss, has made the grassland and shrubland bird communities particularly vulnerable to extinction. Climate change-induced drought reduces net primary productivity, food availability, habitat quality, and alters vegetation structure. These factors collectively increase mortality in grassland and shrubland birds. However, limited data on habitat use by tropical birds hampers the development of effective management plans for drought-affected landscapes. We examined the foraging sites of 18 shrubland bird species, including two endemic and four declining species, across three shrubland forest sites in the Eastern Ghats of India during the dry season. We recorded microhabitat features within an 11 m radius of observed foraging points and compared them with random plots. Additionally, we examined the association between bird species and plant species where a bird was observed foraging. Foraging sites differed significantly from random plots, indicating active selection of microhabitats by shrubland birds. Using linear discriminant analysis, we found that the microhabitat features important for the bird species were presence of ground cover, shrub density, vegetational height, and vertical foliage stratification. Our results show that diet guild and foraging strata influence the foraging microhabitat selection of a species. Microhabitat attributes selected by shrubland specialist species differed from those of generalist shrubland users. Thirteen out of 18 focal species showed a significant association with at least one plant species. Birds were often associated with plants that were green during the dry season. Based on habitat selection and plant associations, we identified several habitat attributes that can be actively managed. Despite being classified as wastelands, the heavily degraded shrub forests can be rehabilitated through strategic and selective harvesting of forest products, targeting invasive species, and a spatially and temporally controlled livestock grazing regime. Full article

Fagaceae trees dominate in the temperate and subtropical forests in East Asia. Understanding the spatial patterns of their carbon contents and the influencing factors can support high-precision forest carbon accounting. A comprehensive understanding of the changes in carbon in multiple organs of trees such as Fagaceae trees is still lacking at a large scale. This study investigated the inter-tissue variation, spatial patterns, and climatic drivers of carbon fraction across nine tissues (leaves, branches, bark, sapwood, heartwood, stump, coarse roots, medium roots, and fine roots) in 41 Fagaceae species (5 genera) from 12 sites across China’s major forest biomes. The sampling sites ranged from northern temperate to northern-tropical and covered an elevation range of 1200 m. The carbon fraction was measured with dry combustion after dried at 60 °C. Variance decomposition revealed that geographical location was the dominant source of variation (16%–55%), outweighing differences at the species and genus levels. Significant disparities in carbon fraction were observed among tissues, following a general pattern of leaves (517 mg g⁻¹) ≈ fine roots (516 mg g⁻¹) > heartwood (510 mg g⁻¹) > sapwood (504 mg g⁻¹) > branches (501 mg g⁻¹) ≈ medium roots (500 mg g⁻¹) > bark (495 mg g⁻¹) > coarse roots (488 mg g⁻¹) ≈ stump (487 mg g⁻¹). This indicated a “high-at-both-ends” arcuate pattern from leaves to fine roots. Spatially, carbon fractions in most tissues exhibited significant declining trends with increasing latitude and eastward longitude. Generalized additive models identified mean annual temperature and precipitation as the most influential factors for most above-ground tissues, while fine roots were primarily regulated by temperature seasonality. These findings help us understand the differences in tree carbon fraction from an organ perspective, highlighting the critical importance of multi-tissue sampling protocol. We recommend integrating the spatial and climatic drivers for refining forest carbon accounting. More species should be included to separate the species and climatic effects in the future. Full article

Rising temperatures are among the most predictable outcomes of climate change, and cacti are particularly vulnerable at the germination stage. We tested seeds of ten Cuban Leptocereus species from coastal and inland habitats under five temperature regimes to evaluate germination responses, thermal buffering capacity for optimal germination, photoblastic behavior, recovery after heat stress, and seedling vigor. Germination declined sharply with increasing temperature, revealing minimal thermal buffering capacity for optimal germination. All species exhibited positively photoblastic seeds, while recovery and the degree of physiological dormancy varied among taxa. Except for one taxon, most displayed partial dormancy that could stagger germination over time. Seedling vigor was not affected by high temperatures in the same way in all species. Overall, our findings suggest that climate warming will further constrain the germination niche of Leptocereus, underscoring the importance of conservation measures such as ex situ propagation. Full article

Habitat fragmentation profoundly alters ecological processes such as seed predation and dispersal. Ants play a central role as seed removers and dispersers, yet the effects of fragmentation on seed-carrying ant assemblages in dry tropical forests remain insufficiently studied. In this work, we examined the influence of forest fragmentation on seed-carrying ants in the Chaco forests of central Argentina. Ants were sampled across nine forest fragments of varying sizes and two continuous forests within an agroecosystem landscape, and species richness, composition, and occurrence were analyzed. Our results revealed that species richness did not vary significantly with fragment size; however, fragmentation caused pronounced shifts in species composition, with clear distinctions between continuous forests and fragments. Large-bodied specialist harvester ants declined in fragments, whereas small- to medium-sized generalist species from genera such as Pheidole and Solenopsis persisted. These compositional changes suggest that although overall seed removal rates may remain stable, the functional quality of seed dispersal likely diminishes. This study highlights the sensitivity of seed-carrying ant assemblages to habitat fragmentation and underscores the need for further research that integrates behavioral and landscape-scale approaches to better assess impacts on seed removal, dispersal, and forest regeneration in fragmented dry forests. Full article

The previously published liverwort checklist of Laos, one of the least-studied countries in Asia, was titled “Listing the Unknown”, based on the fact that only 66 species are known for such a landscape-diverse country. Our collection revealed 39 genera and 76 species, 62 of which are newly recorded species to the country, bringing the total number of known species to 128. Among the reported genera, there are 22 liverwort genera new to Laos, all of which could have been expected in this area. Although new data expands the species list, the total number of species recorded remains inadequately small. The presented studies are based primarily on collections at lower elevations (below 500 m above sea level), in strongly modified secondary forest conditions, and are of interest specifically as an example of the liverwort flora of heavily modified, anthropogenically disturbed habitats of rather dry tropical forest communities. The provided checklist includes data on the ecological conditions of the collected species and their altitudinal range. Further research on the liverwort flora of Laos should be conducted in the upper altitudinal zones of the north and the east of the country. Full article

Volcanic crater interiors in Nicaragua’s Pacific region are a valuable, understudied, and threatened native plant resource. Laguna de Apoyo Nature Reserve encompasses a crater and lake formed following a Quaternary volcanic explosion in Pacific Nicaragua. The flora of the tropical dry forest in the crater’s interior surrounding the lake has not been extensively assessed. We identified 403 native and 72 introduced plant species and their uses through a combination of survey plots, unstructured interviews, expert consultations, and targeted searches for plant species coordinated with key informants in the Reserve. Fabaceae, Euphorbiaceae, and Asteraceae were the most represented native species, whereas the most significant numbers of introduced species were found in Poaceae, Euphorbiaceae, and Fabaceae. Forty-one species have conservation priority status. Documented uses were found for 70% of the native species and 88% of the introduced species. The most significant numbers of plant species with reported use types were ornamentals and fuelwood. This study constitutes the most comprehensive plant species inventory in a protected area of Nicaragua’s tropical dry forest biome. These findings indicate native plant diversity is high, introduced species pose considerable risks, and most species are integrated into local uses. Consequently, management decisions should explicitly promote native diversity, protect threatened species, better control introduced species, and encourage sustainable use. Full article

High-resolution NICFI-Planet image collection on Google Earth Engine (GEE) promises fine-scale tropical forest monitoring, but persistent cloud covers, shadows, and haze undermine its value. Here, we present two simple, fully reproducible cloud-masking algorithms. We introduce (A) a Blue and Near-Infrared threshold and (B) a Sentinel-2-derived statistical thresholding approach that sets per-band cutoffs. Both are implemented end-to-end in GEE for operational use. The algorithms were first developed, tuned, and evaluated in the Sundarbans (Bangladesh) using strongly contrasting dry- and monsoon-season scenes. To assess their broader utility, we additionally tested them in two independent deltaic mangrove systems, namely, the Bidyadhari Delta in West Bengal, India, and the Ayeyarwady Delta in Myanmar. Across all sites, Algorithm B consistently removes the largest share of cloud and bright-water pixels but tends to over-mask haze and low-contrast features. Algorithm A retains more usable pixels; however, its aggressiveness is region-dependent. It appears more conservative in the Sundarbans but noticeably more over-inclusive in the India and Myanmar scenes. A Random Forest classifier provided map offers a useful reference but the model is dependent on the quantity and quality of labeled samples. The novelty of the algorithms lies in their design specifically for NICFI-Planet basemaps and their ability to operate without labeled samples. Because they rely on simple, fully shareable GEE code, they can be readily applied in regions in a consistent manner. These two algorithms offer a pragmatic operational pathway: apply them as a first-pass filter keeping in mind that its behavior may vary across environments. Full article

Wildfires are a recurring dry-season hazard in northern Thailand, contributing to severe air pollution and trans-boundary haze. However, the region lacks the ground-based measurements necessary for monitoring Live Fuel Moisture Content (LFMC), a key variable influencing vegetation flammability. This study presents a preliminary framework for near-real-time (NRT) LFMC estimation using Sentinel-2 multispectral imagery. The system integrates normalized vegetation and moisture-related indices, including the Normalized Difference Vegetation Index (NDVI), the Normalized Difference Infrared Index (NDII), and the Moisture Stress Index (MSI) with an NDVI-derived evapotranspiration fraction (ETf) within a heuristic modeling approach. The workflow includes cloud and shadow masking, weekly to biweekly compositing, and pixel-wise normalization to address the persistent cloud cover and heterogeneous land surfaces. Although currently unvalidated, the LFMC estimates capture the relative spatial and temporal variations in vegetation moisture across northern Thailand during the 2024 dry season (January–April). Evergreen forests maintained higher moisture levels, whereas deciduous forests and agricultural landscapes exhibited pronounced drying from January to March. Short-lag responses to rainfall suggest modest moisture recovery following precipitation, although the relationship is influenced by additional climatic and ecological factors not represented in the heuristic model. LFMC-derived moisture classes reflect broad seasonal dryness patterns but should not be interpreted as direct fire danger indicators. This study demonstrates the feasibility of generating regional LFMC indicators in a data-scarce tropical environment and outlines a clear pathway for future calibration and validation, including field sampling, statistical optimization, and benchmarking against global LFMC products. Until validated, the proposed NRT LFMC estimation product should be used to assess relative vegetation dryness and to support the refinement and development of future operational fire management tools, including early warnings, burn-permit regulation, and resource allocation. Full article

Evapotranspiration (ET) plays a vital role in understanding water and energy cycles in forest ecosystems, particularly in tropical regions where rubber plantations are widespread. In this study, a rubber plantation system was used. By combining meteorological data from flux towers and 30 periods of Landsat-8 image data, we estimated the daily ET of a rubber plantation from 2022 to 2024 using the Surface Energy Balance System (SEBS) model. Additionally, the study employed the eddy covariance method to validate the accuracy of the daily average ET estimated by the SEBS model in different source areas, in order to explore the model’s applicability. Simultaneously, we examined the key drivers influencing ET in rubber plantations by analyzing meteorological factors and physiological growth indicators. The results indicated that the SEBS model exhibited the highest estimation accuracy (R² = 0.90, RMSE = 0.43 mm, RE = 15.23%) for the rubber plantation ET in the region 1.5 km away from the flux tower, and the retrieval accuracy of 30 periods of ET was higher (RMSE ≤ 1 mm, RE ≤ 46.84%), indicating that the SEBS model was well-suited for estimating ET in rubber plantations. From 2022 to 2024, the daily average and monthly cumulative ET showed a unimodal distribution, with high summer and low winter values; the average monthly accumulated ET during the wet season (102.75 mm) was found to be significantly greater than that during the dry season (50.61 mm). On the daily and monthly scales, the correlation between atmospheric pressure, temperature, and ET was the most significant. These findings enhance our understanding of rubber plantation water use patterns and support the application of remote sensing models for regional water resource management, offering valuable insights for optimizing irrigation strategies and ensuring sustainable rubber production in tropical regions. Full article

Characterizing the botanical composition of pollen is essential to understanding the floral resources used by bees. While microscopy is the traditional method, it is time-consuming and limited in taxonomic resolution. Molecular tools such as DNA barcoding offer a more precise and cost-effective alternative for identifying plant taxa in mixed pollen samples. This study implemented a preliminary and cost-effective molecular approach to identify the botanical origin of pollen stored in bee bread from Apis mellifera hives in a tropical dry forest fragment in La Paz, Cesar, using rbcL and matK genes as markers. The chloroplast markers rbcL and matK were amplified and Sanger-sequenced from three independent bee hives, each processed in duplicate as technical replicates. The BLAST+ 2.17.0 results from Sanger sequences showed a sequence identity ranging from 89%–99%, with rbcL showing higher and more consistent matches than matK, suggesting stronger discriminatory power, while the lower identity in one hive indicated a more complex pollen mixture. However, matK detected a greater number of taxa overall (i.e., 70% of the total, 64 genera) compared with rbcL (i.e., 50%, 46 genera). Both markers overlapped in approximately 20% of the taxa, most of which (i.e., 94%) belonged to the family Cactaceae. This indicated that, although rbcL provided more reliable matches, matK contributed to broader taxonomic coverage, highlighting the complementarity of both markers for mixed pollen analyses. This approach highlights its value as an exploratory tool prior to applying high-throughput sequencing strategies. Furthermore, such studies may support the development of local honey brands by validating that their products originate mainly from the biodiversity of tropical dry forests, an ecosystem currently at risk, thereby conferring both ecological and market value. Full article

Mango (Mangifera indica L.) is a tropical fruit tree characterized by vigorous growth and high fruit production, making it one of Peru’s main export crops. However, its extensive vegetative development requires substantial space, limiting productivity per unit area. This study evaluated the effects of rootstock and interstock combinations on agronomic traits and fruit biometrics, highlighting the potential of interstocks to modulate tree vigor in mango orchards of Peru’s dry forest region. A total of 216 trees were established using ‘Chulucanas’ and ‘Chato’ as rootstocks and ‘Chulucanas,’ ‘Chato,’ ‘Irwin,’ and ‘Julie’ as interstocks, apically grafted with the ‘Kent’ cultivar, with a spacing of 6.0 m × 6.0 m. Tree performance was assessed after 10 years during the 2017–2019 growing seasons in Piura, Peru, under a randomized complete block design (2 × 4 factorial). The combination of the ‘Chulucanas’ rootstock with ‘Chulucanas’ and ‘Julie’ interstocks reduced tree height by 10.94% and 11.70%, respectively, facilitating orchard management and potentially increasing planting density. Yield varied significantly among growing seasons, with a 15% reduction in 2017 attributed to El Niño–Southern Oscillation (ENSO)-related increases in temperature and rainfall that affected flowering and fruit set. These results underscore the importance of cultivar selection and climate-adaptive strategies to sustain mango productivity in regions prone to climatic variability. Full article

Understanding and quantifying the coupled effects of land cover change and climate change on hydrological regimes is critical for sustainable water management in tropical mountainous regions. The Río Negro Basin in eastern Antioquia, Colombia, has undergone rapid urban expansion, agricultural intensification, and deforestation over recent decades, profoundly altering its hydrological dynamics. This study integrates advanced satellite image processing, AI-based land cover modeling, climate change projections, and distributed hydrological simulation to assess future streamflow responses. Multi-sensor satellite data (Landsat, Sentinel-1, Sentinel-2, ALOS) were processed using Random Forest classifiers, intelligent multisensor fusion, and probabilistic neural networks to generate high-resolution land cover maps and scenarios for 2060 (optimistic, trend, and pessimistic), with strict area constraints for urban growth and forest conservation. Future precipitation was derived from MPI-ESM CMIP6 outputs (SSP2-4.5, SSP3-7.0, SSP5-8.5) and statistically downscaled using Empirical Quantile Mapping (EQM) to match the basin scale and precipitation records from the national hydrometeorological service of the Colombia IDEAM (Instituto de Hidrología, Meteorología y Estudios Ambientales, Colombia). The TETIS hydrological model was calibrated and validated using observed streamflow records (1998–2023) and subsequently used to simulate hydrological responses under combined land cover and climate scenarios. Results indicate that urban expansion and forest loss significantly increase peak flows (Q90, Q95) and flood risk while decreasing baseflows (Q10, Q30), compromising water availability during dry seasons. Conversely, conservation-oriented scenarios mitigate these effects by enhancing flow regulation and groundwater recharge. The findings highlight that targeted land management can partially offset the negative impacts of climate change, underscoring the importance of integrated land–water planning in the Andes. This work provides a replicable framework for modeling hydrological futures in data-scarce mountainous basins, offering actionable insights for regional authorities, environmental agencies, and national institutions responsible for water security and disaster risk management. Full article

Protected area coverage is set to expand in response to climate change and the biodiversity crisis, but we lack assessments of wildfire incidence in protected areas. Here, we quantify biogeographical variation in global patterns of burned area in protected areas. During the twenty-first century, wildfires have burned 2 billion hectares of protected areas—an area the size of Russia and India combined—and, while protected areas only cover 19.2% of semi-natural ecosystems, they concentrate 28.5% of the area burned annually. Wildfire in protected areas increased significantly between 2001 and 2024 (+0.46% yr⁻¹), even after taking into account increases in protected area (+0.27% yr⁻¹), pointing to a disproportional impact of fire on protected areas under increasingly severe fire weather. This pattern showed marked variation across biomes, with the largest disproportionate increases occurring in fire-prone biomes (e.g., Mediterranean and dry tropical forests, tropical grasslands, and xeric shrublands). There were important exceptions to this general trend, and protected area fire was lower than expected in biomes where fire activity is naturally limited by moisture (e.g., tropical rainforests or montane grasslands). Wildfires are important for the health of many ecosystems, and such values of burned area will not always mean a negative outcome. Amidst concerted efforts to expand protected area coverage, such as the Global Biodiversity Framework, our results highlight the need for new management strategies that address the globally increasing impacts of burned area across protected areas under unabated climate change. Full article

Understanding wild bee diversity is critical for pollinator conservation, particularly in understudied tropical regions like coastal Ecuador. This preliminary study provides a photography-based assessment of bee diversity at Finca Botánica, an organic and regenerative farm on Ecuador’s central Pacific coast. Over a 10-day survey in December 2024, researchers documented 51 bee species across four families, with Apidae being the most represented. The study highlights a predominance of solitary, ground-nesting bees and a lower-than-expected diversity of Meliponini (stingless bees) and Euglossini (orchid bees) compared to other regions of Ecuador. Many species were found in forest patches, ecological corridors, and cover-cropped maize fields, underscoring the role of sustainable farming practices in supporting pollinator diversity. While photographic methods provided valuable preliminary data, they also revealed limitations in species-level identification, reinforcing the need for future specimen-based surveys. These findings suggest that Ecuador’s dry coastal forests may harbor a richer bee community than previously recognized and that organic farms can serve as important refuges for native pollinators. Full article