Early- and late-dry season fires proved less conducive to earthworms than prescribed mid-dry season fire after eight years in the Lamto tropical savannah

Molecular characteristics of organic aerosols and impacts of transboundary biomass burning in Southwest China.

Background Recurrent large wildfires have become a global problem threatening human lives and assets. Extreme fire weather conditions and cured biomass increase the chances of severe and high-intensity fires that can be hard to control. The Cerrado is a tropical humid savanna with frequent, late dry season (LDS) large wildfires prevailing in protected areas. Since 2014, prescribed early dry season (EDS) fires have been applied within the integrated fire management approach. Aims To assess effects of relative humidity and fuel load on fire intensity and fuel consumption. Methods We undertook experimental fires during early and late dry seasons, during day and evening and in areas with different fuel loads. Key results We found that: (1) EDS fires under lower air relative humidity daytime conditions yielded similar fire intensities to LDS fires; (2) under higher relative humidity evening conditions, EDS fires exhibited lower intensities, which also varied with available fuels in different years. Conclusions Fire management in Cerrado landscapes should consider taking advantage of different diurnal, seasonal and fuel load conditions to address specific management objectives. Implications Acknowledging different local conditions can enhance management cost benefits.

Burned area trends in Niassa Special Reserve, Mozambique, are mostly driven by late dry season fires and weakly dependent on climate

ABSTRACTSeasonal acclimatisation is a mechanism enabling individuals to advantageously adjust one or more physiological parameters in response to changing environmental conditions. The ability to adjust metabolic rates and thermal physiology in response to seasonal changes is known to be central to the physiological ecology of some reptiles, but few studies have examined the ability of reptiles to exhibit seasonal flexibility in rates of evaporative water loss (EWL). We measured acclimatisation to seasonal changes for both temperature and water-related traits in six species of geckos in the genus Gehyra from the highly seasonal tropics of northern Australia. Four species from a mesic, more thermally stable site did not have seasonal differences in thermal preference (Tpref), but Tpref was significantly lower during the cooler dry season in three species from a semi-arid, more thermally variable site. EWL was lower (34–76% reduction) during the dry season compared with the wet season, representing a significant reduction for all gecko species. EWL decreased rapidly from wet to early dry season, then either remained low or continued to decrease to a minimum in the late dry season. These results indicate acclimatisation in EWL, resulting in the conservation of water during the dry season. A growing body of evidence suggests that seasonal acclimatisation of EWL broadly occurs in lizards in the wet–dry tropics of Australia, but less is known about seasonal acclimatisation of EWL in other geographic regions.

Simuliid flies (blackflies) of the family Simuliidae are ecologically and epidemiologically significant in as obligate vectors of Onchocerca volvulus, responsible for onchocerciasis. Their breeding habitats, seasonal abundance, biting activity, and developmental characteristics is essential for assessing transmission risk and improving vector surveillance. Despite onchocerciasis endemicity in Ondo State, ecological documentation of simuliid populations in specific river systems within Ondo City remains limited. This study investigated the ecological characteristics of simuliid flies along a river on Laje Road, Ondo City. Field sampling was conducted at three sites along a fast-flowing river section during the late rainy season (June–August 2024) and early dry season (October–November 2024). Water depth ranged from 16.5–59.0 cm and velocity averaged 0.8 m/s at the fastest site. Overall seasonal mean air temperatures were 27.1°C (rainy season) and 29.9°C (dry season onset) while water temperature exhibited considerably narrower variation, ranging only from 25.2°C to 27.2°C. The narrow thermal range falls within the optimal developmental range (20-28°C) for Simulium damnosum. A total of 55 adult flies were captured, with peak abundance in June and July, and peak biting activity between 1400 and 1700 hours. Adult morphometric measurements showed wing length (mean 8.41 ± 0.47 mm). Thorax length (mean 5.62 ± 0.48 mm); thorax depth (mean 5.28 ± 0.56 mm). Head length (mean 4.04 ± 0.51 mm) and leg length (mean 8.50 ± 0.59 mm). Dimensions are consistent with reference measurements for female S. damnosum. These findings confirm the river as an active simuliid breeding and biting habitat.

The Gilé National Park (PNAG for its acronym in Portuguese), located in central Mozambique is one of the most important protected areas in the country. It is one of the last remnants of intact Miombo woodlands, providing critical habitat for endemic biodiversity. Fires are an important ecological factor in Miombo, but changes in fire regimes may compromise the stability of this ecosystem and thus, the conservation value of PNAG. This study assessed fire patterns and mapped fire risk in support of adaptive management in the PNAG. We investigated Miombo fire regime over 23 years (2001 to 2023) in terms of return interval, frequency, temporal distribution, spatial density and intensity, extent, and severity, by using two Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite products (MCD14ML active fire; MCD64A1 burned area). Primary risk drivers were established and spatial fire likelihood mapped, using the Random Forest algorithm. Analysis revealed pronounced late dry season burning (August–October) affecting approximately 60% of the PNAG annually, especially in central-northern and eastern landscapes. Remarkably, 88% of the park maintains a 1-to-2-year fire return interval across the entire fire season (May–October) while only 7% maintains return frequencies of 3-to-4-year cycles. The latter is important for maintaining Miombo ecosystem functionality. Medium to medium–high fire severity covered 98% of the total fire extension. Climate-related drivers and hunting activities were identified as key fire initiators, especially in central areas of the park. The findings demonstrate an urgent need for spatially differentiated fire management action through prescribed burning to maintain PNAG’s ecological resilience and conservation value.

ABSTRACT This article examines how borders in the context of Fulani transhumance in West Africa are not fixed lines of demarcation, but dynamic spatiotemporal processes shaped by the shifting ecological rhythms of the dry and rainy seasons. Drawing on trajectory ethnography , we trace how Fulani pastoralists encounter, negotiate, and navigate border controls during seasonal movements – patterns which are becoming increasingly variable under climate change. Combining the concepts of borderscapes and riskscapes, the study shows how everyday practices – such as issuing vaccination papers, regulating bush-path access, and managing encampments – shift in response to erratic rainfall, fluctuating pasture availability, and land-use conflict. Our findings reveal that mobility is most restricted during the early dry and wet seasons, when Fulani movement is framed as a threat to crops or security, but becomes more normalised in the late dry season, when it is reinterpreted as beneficial for local livelihoods. However, pastoralists with greater access to documents, technologies, and social networks are more able to adapt to ecological cycles and navigate controls, leading to differentiated experiences of mobility. We conclude that bordering is deeply embedded in these shifting ecological dynamics that determine how, when, and where mobility is enforced or contested.

Heatwaves are intensifying globally under anthropogenic climate change and increasingly co-occur with degraded air quality, forming compound environmental hazards with amplified impacts on human health. While such heat–pollution interactions have been widely documented in mid-latitude regions, observational evidence from tropical rainforest environments remains scarce. This study examines the relationship between heatwaves and particulate matter (PM₂.₅ and PM₁₀) in Santarém, an urban center in the central Amazon, using continuous observations from a low-cost monitoring network and meteorological data collected throughout 2023. Heatwaves were identified using the CTX90pct index based on long-term maximum temperature records, and daily particulate concentrations were analyzed through descriptive statistics, categorical classification, and regression modeling. Both PM fractions exhibited substantially higher concentrations during heatwave periods, particularly in the late dry season under severe drought and biomass-burning conditions. Mean PM₁₀ increased from 17.1 to 25.4 µg m⁻³ and PM₂.₅ from 9.5 to 15.8 µg m⁻³ on heatwave days, accompanied by a shift toward higher pollution categories. Multiple linear regression identified air temperature as the dominant driver of particulate variability, while relative humidity exerted a mitigating effect. Heatwave occurrence was significantly associated with increased PM₁₀ concentrations, whereas PM₂.₅ responded mainly through enhanced extremes. Logistic regression further indicated that elevated PM₁₀ concentrations on the preceding day increased the probability of heatwave onset, suggesting that coarse particles act as indicators of pre-heatwave atmospheric stagnation Overall, the results demonstrate that heatwaves in the Amazon are embedded within broader periods of atmospheric degradation characterized by dry, stagnant conditions that promote particulate accumulation. These findings provide the first observational evidence of compound heat–pollution events in an Amazonian city and highlight the need for integrated heat and air-quality monitoring and early-warning strategies to reduce public-health risks in tropical regions.

Abstract Gape size is a key functional trait that influences feeding performance and ecological fitness across animal taxa; yet, its role within species remains underexplored, particularly in dynamic environments. We investigated the relationship between relative gape size and condition factor ( Kn ) across 15 species of tropical freshwater fish from northern Australia, spanning four trophic groups: predators, micro-carnivores, omnivores, and herbivores/detritivores. Using linear mixed-effects modelling, we assessed how this relationship varies across trophic groups and seasonal hydrology. Our results revealed a strong positive association where larger gape sizes were associated with enhanced body condition in predators and, to a lesser extent, micro-carnivores—especially during the mid- and late-dry seasons when resource availability is reduced. In contrast, this relationship was weak or absent in omnivores and herbivores/detritivores, whose diets are less likely to be gape-limited. These findings suggest that the functional benefits of larger gape sizes are context-dependent, conferring greater fitness advantages to carnivorous species under seasonal resource limitation than to other trophic groups. Our study highlights the need to consider both trophic ecology and seasonal variability in resource availability regimes when linking traits to performance and provides empirical support for the context-dependent utility of gape size as a functional trait in ecological research.

Abstract The Brazilian Amazon contains approximately 40% of the world's tropical rainforest and plays a critical role in preserving biodiversity and regulating water, energy and carbon cycles. However, deforestation and increasingly frequent droughts, heatwaves and wildfires threaten these rainforests. Amazonian fires are generally assumed to be entirely anthropogenic, which has led to lightning-ignited fires being underexplored. Here, we present the first detailed assessment of the spatiotemporal patterns of lightning-ignited fires in the Amazon rainforest to elucidate the role of lightning and human ignitions in shaping Amazon fire dynamics. To do this, we matched cloud-to-ground lightning strokes from the Global Lightning Dataset (GLD360) with individual fire events between 2019 and 2024 to obtain a probability of lightning ignition for each fire. We also calculated a human-ignition probability index using proximity to roads, waterways, and human land cover as proxies for human activity. By combining both probabilistic indices with ground-observed lightning ignitions from eight protected areas, we could optimize the threshold that determines if an ignition is more likely to be caused by lightning or human activities. We estimate that in the Brazilian Amazon, lightning caused on average 0.2–0.4% of all fires each year (234–407 ignitions per year) and 1.1–1.2% of the annually burned area (1,226–1,358 km2 per year) between 2019 and 2024. More than 89% of these fires occurred in the late dry season between August and November, peaking in September and October. Despite lightning-ignited fires contributing a small proportion of all Amazonian fires, they constitute over 25% of the fires in identified grid clusters in parts of the states of Pará (particularly in the Breves region), Amazonas, and Rondônia. This study provides the first estimation of the role of natural ignitions in Amazon fire dynamics and a scientific basis for understanding their contribution within the region.

ABSTRACT Fire and large mammal herbivores play major roles in shaping plant communities in savannas. However, the interactive effects of these drivers on other components of savanna biodiversity are less well understood. This study, conducted in Gorongosa National Park, Mozambique, tested the effects of fire and large mammals on the abundance and richness of foraging granivorous and insectivorous birds. We manipulated the presence of large mammals and early and late dry season burns and measured multiple aspects of grasses and woody plants as well as bird foraging. We modeled the abundance and richness of foraging birds in response to tree basal area, shrub abundance, grass biomass, grass cover, and grass richness in plots with and without large mammals and fire in the wet season prior to experimental burns, in the dry season following the burns, and in the subsequent wet season. Early and late dry season burns increased granivorous bird foraging in the wet season following the fires. Foraging insectivores increased in plots with cold burns 4 months after fire. The exclusion of large mammals generally reduced bird foraging, although positive effects of large mammal exclosures were detected when resources were limited, and fire and large mammals indirectly affected foraging by changing vegetation and therefore seed and arthropod food resources. Foraging was higher for both guilds where tree cover was greater, and foraging of insectivores increased with shrub cover and grass biomass and richness. These results emphasize the importance of considering fire‐herbivore interactions for the conservation of savanna biodiversity.

A landsat-based burned area atlas (2000–2023) for the Niassa Special Reserve, Mozambique using U-Net deep learning

ABSTRACT Although bees have been extensively studied, other less charismatic insect groups, such as Diptera and Coleoptera, are often overlooked. However, these are widespread and integrate pollination networks, being dominant in specific habitats such as high‐altitude regions. However, important knowledge gaps consist of: (1) most network studies are conducted in temperate mountains with limited data for tropical ones, (2) neglected pollinators are not the focus of investigations, and (3) most studies have a short temporal scale, without investigating seasonality effects throughout the year. To fill these gaps, we studied several sites in the Espinhaço Mountain Range (EMR), a local area with exceptional biodiversity and endemism. We compared the networks between the southern and northern areas across four seasons: early and late dry, and early and late wet seasons. We found two times more interactions between plants and pollinators in the southern than in the northern EMR. Plants engaged in Coleoptera and Diptera‐mediated pollination are, in general, white, mass‐flowering, and belong to Asteraceae, Cyperaceae, and Eriocaulaceae families. The number of interactions decreased from early wet to end dry, both in southern and northern EMR. Specialisation slightly increases over the seasons in the southern EMR but decreases in the northern. In general, nestedness was higher in the dry season. Networks are, in general, modular. Modularity was higher in the early wet season, progressively decreasing over the seasons in both areas. In conclusion, given the ecological dominance of Eriocaulaceae, Asteraceae, and other plant families in the EMR, the decline of Diptera and Coleoptera could imply cascading effects across the ecosystem. Also, as the networks change over the climatic seasons in this tropical mountain, this highlights the importance of understanding the complex effect of climate change on the EMR plant‐pollinator interactions.

A study on the effects of depth and water quality on aquatic plant distribution in Nong Han Lake, Sakon Nakhon Province, Thailand, was conducted by surveying species diversity and biomass of aquatic plants along with physical and chemical parameters across 43 sampling stations. The survey was carried out during early dry season 2020, late dry season 2021, early rainy season 2021, and late rainy season 2021. The year-round survey revealed a total of 61 species from 30 families, with emergent plants being the dominant group. The most frequently encountered species across all seasons was the curly pondweed (Potamogeton crispus L.). Cluster analysis categorized the sampling stations into three groups based on water depth. A highly significant negative correlation (P<0.01) was found between water depth and species richness, while no correlation was observed between depth and aquatic plant biomass. Water quality in Nong Han Lake was generally good, except for some areas during the rainy season where water quality deteriorated. The findings indicate that Nong Han Lake has potential as an appropriate primary production source in the aquatic ecosystem. However, problems arising from dense aquatic plant distribution can lead to water body deterioration, particularly in littoral zones where plant debris accumulation may result in shallow, stagnant, and deteriorated conditions. Therefore, measures should be implemented to reduce nutrient loading into the water body and to optimize the harvesting of aquatic plants for maximum utilization.

The African forest elephant (Loxodonta cyclotis) has recently been recognized as its own distinct species and classified as critically endangered. There is increased concern regarding how forest elephants will respond to their continuously deteriorating ecosystems due to climate change and habitat loss and fragmentation. Scoring an animal's body condition is non-invasive, quick, and can serve as a proxy for monitoring its health and nutritional status. This study developed the first forest elephant specific body condition scoring (BCS) system and then investigated how sex, age, rank, and season associated with adult male and female BCSs at the Dzanga Bai forest clearing, Dzanga-Ndoki National Park (Central African Republic), using photographs taken during the early (December 2022-January 2023) and late dry (February-March 2023) season. The developed BCS system was based on systems used for Asian (Elephas maximus) and African savannah (L. africana) elephants and relied on reference photographs and an accompanying flow chart. Male forest elephants had significantly higher BCSs compared to their female counterparts, while no difference by age or rank was observed. Female forest elephants demonstrated a decline in BCS between the early- and late-dry season. Together, these results highlight different factors that may impact forest elephant condition, potentially reflecting the individual's overall health state.

Gopher tortoises (Gopherus polyphemus) are threatened burrowing keystone ecosystem engineers indigenous to open uplands in the Southeastern United States. Perils to the species include habitat degradation and fragmentation, anthropogenic disturbances, predation, parasites, and disease. Problems are severe in the SE Florida study area due to coastal urban sprawl, confining the tortoises in small, scattered, unnatural pockets subject to novel stresses. The annual South Florida February to ca. late May dry season became a severe drought in 2025. The present project centered on the broad question of foodplant resilience through the drought. The tortoise-grazed areas host three dominant groundcover species, in order of abundance: non-native Richardia grandiflora, native grass Paspalum setaceum, and non-native sedge Fimbristylis cymosa. Key findings were as follows: 1. The most abundant and most-often grazed species, Richardia grandiflora, when tortoises were excluded, expanded despite the drought (from 39% to 49.5% mean coverage). Under combined drought and grazing, that species cover decreased slightly (42.5% to 39.4%). Tortoise-free, Paspalum setaceum declined slightly during the drought (32.7% to 27.1% mean coverage), and showed mixed results with little net effect exposed to drought and to grazing. Never observed to be grazed during the study, Fimbristylis cymosa formed a nearly monospecific lawn in a sizeable portion of the study area. During the drought, it mostly browned, retaining green rosette centers, and tortoise exclusion showed no discernable effect. With transition to late spring, however, with increased rainfall, tortoise exclusion allowed rapid competition from grasses among the Fimbristylis rosettes. Adjacent unenclosed grazing, by contrast, maintained the Fimbristylis lawn without increase in grass coverage. Conclusions are that the two chief "fodder" species, Richardia grandiflora and Paspalum setaceum, were robust to drought and grazing. The introduced Fimbristylis cymosa appears to be facilitated by selective grazing-suppressing grass competitors.

ABSTRACT The South American rattlesnake (Crotalus durissus) is widely distributed in Brazil, including isolated populations in savannas within Amazonian and Atlantic forests. We investigated the sexual dimorphism and reproductive ecology of C. durissus from the Brazilian Cerrado to address the following questions: (1) What patterns of sexual dimorphism in morphometric characters are present? (2) Do sexes differ in size at sexual maturity? (3) Does reproduction of males and females vary seasonally? (4) Do females reproduce annually, biennially, or at longer intervals? We found sexual dimorphism with males having larger body sizes and longer tails than females, a pattern likely associated with intra-sexual competition between males. Males reach sexual maturity at a slightly smaller size than females (60.7 vs 62.7 cm snout–vent length). In females, vitellogenesis peaks in the late dry season (September), extending into the early rainy season (October–November). The female reproductive cycle suggests a biennial or more extended pattern, as seen in other rattlesnake species. Males show testes with a turgid appearance and convoluted vas deferens year round.

Background Savanna ecosystems constitute approximately 20% of the Earth’s terrestrial surface and are increasingly under threat from various factors including effects of climate change. In Baikiaea plurijuga-dominated woodlands of Botswana, the combination of destructive fire regimes and large elephant populations has been cited as a major cause of adverse vegetation changes in African savanna and woodland systems. Aims We assessed the status of fire regimes in Botswana’s premium wildlife eco-tourism Chobe region to determine whether market-based fire management could be applied to support broader ecological fire management and employment outcomes. Methods The methods used were: (1) reconstructed fire regimes from the early 1990s coinciding with the cessation of commercial timber exploitation; (2) combined automated MODIS 250 m and manually derived Landsat 30 m burn scar products to generate a 33-year Fire Frequency Index (FFI); (3) classified regional vegetation structural types derived from a 5-year (2021–2024) early dry season Landsat median image; and (4) assessed dry season elephant population density distributions in relation to fire occurrence. Key results Frequent (on average, one in every 2.5 years) and relatively severe late dry season fires were characteristic in more open-canopied legume-dominated savannas and grasslands in the eastern sector of the project area. Elephant distributions in the dry season were independent of fire occurrence. Wildfires plausibly cause relatively greater impacts to Baikiaea-dominated vegetation macro-structure than elephants. Conclusions Multiple factors including national fire exclusion policy contribute to contemporary fire patterning in the Chobe regional landscape. Implications We suggest that carbon market-based approaches have potential for contributing to ecologically sustainable fire management and local employment opportunities.

Abstract The sparseness of ground‐based observations hinders our ability to understand the processes driving the interannual variability (IAV) of the African ecosystem carbon cycle. This study explores the regional pattern of the IAV in net biosphere exchange (NBE), defined as the sum of gross primary production (GPP), respiration, and biomass burning emissions, across Africa and its climate drivers from 2015 to 2021, by integrating satellite‐derived carbon flux estimates. Our analysis reveals that moisture‐driven IAV of GPP determines the IAV of total NBE in Africa, but the magnitude of NBE IAV is not uniformly proportional to the GPP IAV across regions. Though IAV of NBE in eastern and southern grasslands is comparable, the IAV of GPP in the east is 29% ± 9% greater, offset by respiration with higher moisture sensitivity. By contrast, the IAV of NBE in northern forests is around twice that of southern forests, despite a smaller IAV of GPP. The larger NBE IAV is attributed to the higher moisture sensitivity of biomass burning emissions and the stronger temperature sensitivity of respiration in northern forests, which prevents respiration from declining despite significant GPP reductions under dry and warm conditions (e.g., the 2016 El Niño year). We also find that in northern grasslands, unlike other regions, IAV of NBE is primarily determined by respiration, which responds strongly to soil rewetting in the late dry season. Our results underscore the potential of satellite observations in uncovering the drivers of the IAV in the African ecosystem carbon cycle at regional as well as continental scales.