Over the past 25 years, strong droughts and heat events have taken place in south-central Chile, which have negatively impacted forest growth and functioning. Tree growth and xylem anatomical responses to climate through time can be evaluated using tree rings. Nothofagus obliqua is one of the most economically important tree species in Chile. This study focuses on a remnant N. obliqua population growing in the Coastal Range of south-central Chile at Quirihue (36.32° S, 72.47° W), which is exposed to particularly restrictive site and climate conditions. The objective of this study was to evaluate tree growth during recent decades, as well as xylem anatomical variations and their relationships with climate during the 1995-2019 period. To achieve this goal, vessel area and vessel density chronologies were developed. Tree growth experienced a substantial decrease and a shift in temporal variability after the 1943 drought, with its main variability mode changing from a 3-4 year cycle to a low-frequency decadal pattern. Growth was positively related to spring-summer precipitation and negatively related to maximum temperature during the 1960-2020 period. Vessel area was the most climate-sensitive variable, being negatively correlated with summer maximum temperatures and positively correlated with spring-summer precipitation. Our results reveal that the species is able to adjust its vessel size, reducing its vessel area and, in some cases, increasing vessel density during severe droughts. Finally, potential hydraulic conductivity, a proxy for hydraulic function, significantly decreased during the analyzed period, pointing to a long-term hydraulic deterioration that should be monitored in the future.
Range maps for most terrestrial invertebrates generally are not accessible as spatial data. My objective was to build global range maps for 11,844 terrestrial insect species, specifically pollinator species with at least 400 georeferenced records each, by applying species range kernels, which contained about 99% of the records, and polygons of aggregated georeferenced records. Depending on aggregation distance, point aggregation generates a range of polygons, in terms of shape and area. To illustrate, for 225 odonate species that had range maps developed by experts, I selected one of six aggregation distances ranging from 200 km to 5000 km based on resemblance to range maps and fidelity to the georeferenced records. Then to predict aggregation distances for insects without accessible ranges, I modeled variables related to georeferenced records, kernels, and aggregated polygons for six different aggregation distances, based on supervised classification of aggregation distances for 4405 species with ranges. Lastly, I examined the species richness gradients of the species ranges, recognizing incompleteness of sampling. Predicted aggregation distances were predominantly middle distances of 500 km or 1000 km, for 86% of the insect species. Given a six class, complex problem with no true answer of species ranges, model accuracy for aggregation distance was 0.66. Generally, misclassification was only off by one distance, resulting in either better fit in shape or greater connection and coverage. For odonates, the species richness patterns were similar (r = 0.91) between expert range maps and data range maps, which helped to correct sampling deficiencies in georeferenced records. Range maps for invertebrates, without previously spatially available range maps, expand underlying sampling gradients and offer at least provisional range maps, filling the gap of missing spatial data.
Fire strongly shapes habitat selection by herbivores and influences savanna dynamics. With many West African herbivores under threat, understanding how habitat changes affect their selection patterns is essential. This study assessed the determinants of habitat selection and the effects of body mass and diet. Dung counts were used to estimate relative habitat use during the dry season in the Pendjari Biosphere Reserve. Data were collected in 50 × 4 m plots spaced at 100 m along 30 transects. Differences in dung density among body mass groups and diet guilds between burnt and unburnt areas were tested using Mann–Whitney tests, and habitat use of 12 herbivore species was modeled with GLMMs based on fire, vegetation, and predation risk. Browsers significantly selected burnt habitats (p < 0.001), while grazers showed a positive but non-significant association, and mixed feeders preferred unburnt areas. Among grazers, buffalo significantly selected unburnt habitats (p < 0.05). Small herbivores preferred burnt areas with low tree density, medium-sized species favored burnt areas with high grass cover, and large herbivores selected habitats with high canopy cover, low visibility, and greater distance from water (p < 0.05). Grazers were associated with burnt areas characterized by high grass regrowth (p < 0.001). Kob and common duiker selected burnt areas, buffalo and elephant preferred unburnt habitats, and waterbuck selected areas with low fire frequency. Kob, waterbuck, roan, and hartebeest were positively associated with grass regrowth after fire. These findings support adaptive fire management integrating herbivore habitat requirements in West African savannas.
Climate change threatens forest ecosystems by increasing frequency and intensity of extreme climatic events. In southern South America, extreme late-spring frost (LSF) episodes can cause severe leaf damage, leading to reduced tree growth and productivity and shortening the effective growing season. Nothofagus pumilio, a hardwood species Tierra del Fuego forests, is an ecologically important resource providing several ecosystemic services. We evaluated the growth resilience of 50 trees across three sites near treeline in Tierra del Fuego to examine LSF impact by quantifying individual resistance (immediate impact) and resilience (recovery capacity) in response to two distinct extreme frost episodes: a single-year (1979) and consecutive three-year event (2007-2009).The three-year LSF caused significantly greater reductions both in resistance and resilience compared to the single-year event. Statistical modelling revealed that tree resistance was negatively affected by higher frost-day frequency during each event relative to the preceding LSF period, while resilience was reduced by unfavorable (lower temperatures) post-event climatic conditions. Notably, fast pre-event growth rates increased tree vulnerability to the single-year frost event, while they had a weaker effect during the prolonged three-year episode, suggesting a stress threshold beyond which intrinsic growth strategy becomes less relevant. Our findings showed that N. pumilio has a limited capacity to tolerate and recover from multi-year frost stress, highlighting its vulnerability to consecutive extreme climate events. We conclude that conservation strategies for high altitude N. pumilio forests must account for the species’ differential sensitivity to frost event frequency under future climate scenarios.
Foraging ecology is expected to shape how predators respond to variation in key prey, with specialist species predicted to track prey dynamics more closely than generalists. However, empirical tests of these expectations remain scarce in systems where prey availability varies strongly across both space and time. Here, we assess how three sympatric carnivores (European wildcat, red fox, and domestic cat) with contrasting foraging strategies respond to spatiotemporal variation in the abundance of a shared key prey species, the Montane water vole. We used a 10-year dataset from mountain grazing systems in northern Spain, where water vole abundance varied among years and was highly heterogeneous within meadows. We analysed the responses of the three carnivore species at two spatial scales: broad-scale temporal variation and fine-scale spatial heterogeneity. Contrary to expectations, responses did not follow a simple specialist-generalist gradient. Red foxes closely tracked interannual variation in vole abundance. Wildcats showed a weaker, delayed response, whereas domestic cats exhibited no detectable association with vole abundance over time. In contrast, all three species exhibited a strong and consistent aggregative response, concentrating their activity in patches with locally high vole abundance. This combination of divergent broad-scale responses and convergent fine-scale aggregation reveals a pronounced scale dependence in predator-prey coupling. The results highlight the importance of explicitly integrating multiple spatial scales when assessing predator-prey dynamics, and caution against drawing inferences from single-scale analyses in heterogeneous ecosystems.
Litter decomposition is a key process of nutrient cycling in ecosystems, with the root-mediated promoting effect of litter decomposition (RPEld) was quantified as the decomposition rate difference between root-present and root-absent treatments. However, the impact of RPEld on litter decomposition under climate warming in subtropical mountain forests remains unclear. Here, we established warming and root interaction treatments (control, CK; trenching, NR; warming, W; warming and trenching, WNR) in a subtropical forest in Southwest China. The results showed that the decomposition rate constant k value of the warming treatments (W and WNR) was significantly lower than that of the unwarming treatments (CK and NR). Crucially, warming reduced RPEld by 69.9% (from 40.5% to 12.2%). Despite a 21.2% decline in soil water content, warming increased the R2 contribution of soil moisture to litter decomposition, while decreasing that of plant roots by 49.1%, according to variance partitioning analysis. These results indicate warming attenuates RPEld via soil moisture limitation, advancing our mechanistic understanding of litter decomposition under climate change.
The Succulent Karoo Biome (SKB) is distributed in the western and southern parts of South Africa and is an entirely arid global biodiversity hotspot, but it is severely undersampled for spiders. To address this gap, we used a standardized sampling protocol to collect arachnids from four biotopes (open plain, riparian vegetation, eastand west-facing mountain slopes) using three methods along a latitudinal gradient of five adjacent degreesquares in South Africa's arid western interior to determine how latitude, biotopes, sampling methods and climate affect spider assemblages and diversity. A total of 6497 spiders were collected, representing 305 species and 39 families. Beating yielded the most individuals but the fewest species (n = 3710, S = 130), hand collecting in litter the most species and intermediate numbers (n =1646, S = 213) and hand collecting from rocks collected the lowest numbers and intermediate species richness (n = 1141, S = 150). Abundance and species richness showed a general bell-shaped pattern along the transect, peaking at Akkerendam Nature Reserve (n = 1839, S = 129). Hand collecting from leaf litter was the most important contributor to spider species richness, with a lower species accumulation rate than beating or hand collecting from rocks. Spider composition from rocks and leaf litter showed some overlap, whereas beating sampled a highly distinct fauna across sites. In total, 519 specimens were sequenced (cytochrome c oxidase subunit I, COI), and this data is publicly available on the SPIZA project on the Barcode of Life Data System (BOLD).
Islands are centers of endemism but are also among the most vulnerable ecosystems to climate change. Warming, altered precipitation regimes, and sea-level rise threaten island biodiversity, making dispersal a critical process for population persistence and colonization. Understanding dispersal mechanisms is essential for conservation, particularly in island endemics with narrow ranges. We documented fruit maturation, seed dispersal, and seed tolerance to freshwater and seawater exposure in Desmotes incomparabilis, a shrub that is classified as Vulnerable by the IUCN and the sole species of an endemic genus restricted to Coiba Island, Panama. Using video recordings and controlled laboratory observations, we documented seed release, dispersal distance and direction. In a separate experiment, we assessed the potential for secondary dispersal via hydrochory by exposing seeds to freshwater and seawater for one week and then evaluating germination. Seeds of D. incomparabilis were explosively ejected to distances between 0.05 and 4.6 m, with most falling within 1.5 m of the launch position. Dispersal was directionally biased toward northeast under fully controlled indoor conditions. Germination declined from 67% in control seeds to 52% after freshwater exposure and 40% after seawater exposure. This suggests that occasional water-mediated transport may extend dispersal distances beyond the ballistic shadow. Where water-mediated transport occurs, secondary hydrochory may help mitigate some of the demographic and genetic limitations associated with short-distance ballistic dispersal. By linking dispersal mechanism, dispersal distance, directionality, and tolerance to water exposure, this study provides a framework for evaluating conservation risks in narrowly endemic island plants exposed to sea-level rise and habitat fragmentation.
Understanding the traits of host oaks that shape gall wasp communities is critical for predicting the ecological consequences of climate change on these wasp populations. We investigated summer gall occurrences of nine gall wasp species over five consecutive years (2020-2024) on Quercus robur hosts in a common garden plantation in Belgium. Population differentiation among three oak provenances indicated local adaptation: the two non-local provenances (lower-latitude French and higher-latitude Danish) exhibited reduced height growth relative to the local provenance and differed in spring bud burst, autumn leaf senescence and leaf chlorophyll content. Summer gall occurrences were significantly reduced on the lower-latitude provenance, particularly for abundant Neuroterus species, whereas the higher-latitude provenance showed no consistent differences. Gall occurrences were also correlated with host oak leaf phenology: spring bud burst had a stronger effect than autumn senescence, with most wasp species preferring late bud-bursting oaks, although some were associated with early and intermediate phenotypes. Tree height and leaf chlorophyll content influenced summer gall presence for some species, consistent with the plant vigor hypothesis. Multivariate analyses did not reveal clear interspecific interactions among the studied gall wasps. These findings highlight that provenance choice for oak plantations can shape associated herbivore communities, demonstrating that assisted gene flow can have cascading ecological consequences. Inclusion of both sexual and asexual generations in future studies will provide a more comprehensive understanding of host-gall wasp dynamics across seasons.
Understanding how climatic oscillations influence species distributions is key to predicting responses to environmental change. We combined ensemble species distribution modelling and population genetic analyses to reconstruct Late Quaternary habitat dynamics and connectivity in the Sooty Falcon across the Saharo-Arabian region. Models showed high predictive accuracy and identified aridity and thermal variability as primary determinants of breeding suitability. Palaeoclimatic projections revealed strong temporal shifts, with habitat expansion during arid phases and contraction during humid intervals, indicating tight coupling between moisture regimes and range dynamics. Despite major fluctuations in suitable area, some geographically restricted regions remained consistently suitable, suggesting long-term hypothesised climatic refugia. Genetic analyses revealed high diversity and signals of demographic expansion but no significant population structure, consistent with extensive connectivity across the breeding range. Genetic analyses from the Arabian Peninsula revealed high regional diversity and signatures compatible with demographic expansion but no significant population structure; these results are presented as exploratory given the geographic and genomic limitations of the available dataset. Correlations between genetic differentiation and geographic or environmental distances were weak, implying that multiple processes shape spatial genetic patterns. Taken together, our results are consistent with—but do not directly demonstrate—a role for Late Quaternary climatic oscillations in structuring connectivity. Overall, the findings support a dynamic history in which climatic oscillations repeatedly reorganised habitat availability while persistent xeric refugia enabled regional persistence. Continued reductions in suitable habitat since the Late Holocene indicate increasing vulnerability under future climate change and highlight the conservation importance of climatically stable breeding areas.
Figs are characterized by urn-shaped inflorescences called syconia, which protect pollinating fig wasps, the sole partners in an obligate mutualism, from predators and parasites during their developmental stages. However, specific syconium traits, such as the ostiole, that function as defenses against particular predators, and the effectiveness of these defenses, remain poorly understood. This study examined the occurrence rates and species compositions of ants and predatory lance flies using the syconia of seven Ficus species (Ficus benguetensis, Ficus erecta, Ficus microcarpa, Ficus pumila, Ficus septica, Ficus subpisocarpa, and Ficus virgata) as food sources and nesting sites on the Ryukyu Islands of Japan. Twenty-one ant species were recorded in 124 of 434 trees examined in the D phase to the early E phase, including nine tramp species that nest in disturbed habitats. Tramp ants accounted for 70% of all observations, implying that syconia provide food resources that support their persistence in disturbed habitats. Ant occurrence rates on syconia ranged from 18% to 63% across the surveyed Ficus species, likely reflecting interspecific differences in syconium traits. Certain ant species showed high occurrence rates on specific Ficus hosts, with species composition and abundance likely influenced by the habitat characteristics of each Ficus species. One fly species was found in 147 F. erecta and F. pumila trees among 539 trees in the late C phase to the E phase, with emergence frequency exceeding 60%. Thus, ants and flies appear to compete for food resources on the syconia of F. erecta and F. pumila.
Conspecific density dependence is important in explaining the spatial distribution of recruitment and species coexistence, but the role of the quality of surrounding conspecifics in the direction and strength of this dependence remains unclear. Here, we investigated the effects of the densities of viable and inviable conspecific nuts on the establishment of Fagus crenata seedlings in an old-growth beech forest in northern Japan. We sorted F. crenata nuts within litter traps established in 2018, weighed each nut, and counted the viable nuts and inviable nuts. We then investigated seedling emergence near each litter trap in 2019 and explained the success of seedling establishment (the probability of transition from seed to seedling) in terms of the densities of viable and inviable conspecific nuts. The density of viable nuts had a positive effect on the probability of seed-to-seedling transition (i.e., conspecific positive density dependence), and that of inviable ones had a negative effect (i.e., conspecific negative density dependence). We predicted that the seedling density and the optimum nut density that maximized it increased exponentially as the ratio of viable to inviable nut density increased. Our findings suggest that not only the density but also the quality of surrounding conspecifics controls the success of seedling establishment and species coexistence through changes in the direction and strength of conspecific density dependence.
Forest decline has been increasingly observed across different biomes in Brazil and worldwide, with climate change identified as one of its main drivers. Among climatic factors, heatwaves often associated with El Nino events stand out for inducing physiological stress and degradation in plants. Understanding the causes of such stress and forest responses to these events is essential for developing mitigation strategies. This study aimed to characterize the occurrence and severity of heatwaves between 1998 and 2023, to relate climatic data to the Normalized Difference Vegetation Index (NDVI), and to assess stress in native vegetation within the Araucarias State Park, Parana, Brazil. Climatic data were obtained from the Parana Meteorological System (SIMEPAR), and satellite images from LANDSAT 5, 7, 8, and 9 were analyzed. Significant seasonal variations were detected, with NDVI values <= 0.279 indicating possible water stress due to heatwaves. Winter and spring showed the highest incidence of heatwaves, with 1999-2011 identified as the driest and hottest period. El Nino events intensified heat stress by approximately 60%, but an increasing trend in heatwave severity was observed independently, driven by global warming. NDVI data were statistically correlated with climatic stress indicators, allowing identification of the most affected seasons and the delineation of stressed versus healthy forest conditions. NDVI proved to be a valuable methodological tool for assessing heatwave impacts when associated with the Forest Stress Index (FBS). For the Araucarias State Park, NDVI <= 0.279 marked the threshold distinguishing stressed forests. Continuous monitoring is recommended to anticipate potential forest decline or even large-scale mortality.
Question: Livestock grazing is a major land use of dryland ecosystems. While the occurrence of grazing is widespread, there is high heterogeneity in grazing intensity. Biocrusts are responsible for multiple dryland ecosystem services, but livestock trampling can cause crucial disturbance to biocrust communities that may inhibit these contributions. Trampling may be particularly intense around waterpoints, with a decline in trampling with increased distance from the waterpoints. We investigated the effects of this disturbance gradient on biocrust communities. Location: Santa Rita Experimental Range in southern Arizona, USA (31 degrees 49' N, 110 degrees 51 ' W). Methods: We quantified biocrust cover and rates of N2-fixation along grazing gradients extending out from waterpoints. We also measured soil characteristics such as chlorophyll a (a proxy for biocrust biomass), bulk density, soil respiration, and soil water-holding capacity. Results: We found that biocrust cover increased with distance from waterpoints. However, biocrust cover was not correlated with the acetylene reduction assay (an indirect measure of N2-fixation), delta 15N (a direct measure of N2-fixation), or chlorophyll a. Conclusions: These results suggest that grazing negatively affects biocrust cover. We did not find a significant difference between N2-fixation rates among the different distances from the waterpoints or biocrust cover.
Land degradation is a significant global concern, prioritized for restoration actions as part of the Sustainable Development Goals. This study examined the role of area enclosures in promoting nature-based re-vegetation from the soil seed bank, using a comparative approach. Specifically, it compared the aboveground woody flora and soil seed bank between enclosures and open lands in the Central Rift Valley of southern Ethiopia. To conduct this study, one hundred sixty 20 m by 20 m plots were established along six transects using systematic sampling. Furthermore, 640 composite soil samples were collected from four soil layers within 1 m & times; 1 m subplots. The soil seed bank was analyzed using seedling emergence and seed extraction techniques. The results showed that the aboveground vegetation included 56 woody species richness, while soil seed bank contained 34 species richness in enclosures and open lands. In the enclosures, there were 53 aboveground species compared to 28 in open lands. The soil seed bank consisted of 32 species in the enclosures and 18 in open lands. Seed bank density and diversity decreased with increasing soil depth in enclosures and open lands. Moreover, seed densities (m-2) of soil seeds up to 9 cm deep were 0.026 +/- 0.003 for the enclosures and 0.022 +/- 0.003 for open lands. The highest seed density was recorded in the litter and upper layers of both enclosures and open lands. The Sorensen similarity index indicated that the relationship between soil seed bank and aboveground flora was low in open lands, but higher in the enclosures, suggesting a greater potential for restoration. Our findings indicated that the majority of soil seed bank species germinated successfully in the green houses. Therefore, we recommend utilizing enclosures for long-term and continuous restoration of degraded lands and vegetation from the soil seed bank.
The organization of cave invertebrate communities reflects the combined effects of spatial separation among caves, internal habitat heterogeneity, and key environmental features such as shelter availability and trophic resource diversity. Although these factors are recognized as drivers of subterranean biodiversity, their relative influence remains poorly understood in semiarid cave systems, largely due to the scarcity of studies explicitly testing these mechanisms under strong climatic constraints. In this study, we propose that the structure of cave invertebrate assemblages is shaped by both surface-derived (epigean) and subterranean (hypogean) environmental drivers, and that the relative importance of these factors varies across spatial scales in limestone outcrops underlying Caatinga vegetation. To test this hypothesis we surveyed 18 caves distributed across 14 limestone outcrops, sampling two spatial scales that included 26 cave sectors (30 m2 each) and 78 quadrats (1 m2 each). In total, 1228 individuals representing 127 species, including eight troglobitic morphotypes, were recorded. Community composition differed significantly among caves, indicating marked spatial structuring. Variation in assemblage composition was significantly influenced by geographic distance between caves, the presence of guano deposits, and shelter availability within cave interiors. At the mesoscale, species richness exhibited a negative relationship with relative humidity, whereas no environmental variables significantly influenced richness at the microscale. Collectively, these results highlight the importance of spatial scale and fine-scale environmental heterogeneity in structuring subterranean communities, reinforcing patterns documented in cave ecosystems. This study provides new insights into how ecological mechanisms operate under climatically restrictive conditions, with implications for the conservation of karst landscapes.
Forest thinning is a management strategy for Mediterranean woodlands to mitigate climate change effects and reduce fire risk, often leading to increased acorn production from residual trees. However, tree recruitment can be hampered due to effects of vegetation change on key seed dispersers, like the wood mouse (Apodemus sylvaticus). We analyse how thinning affects vegetation structure, acorn availability and wood mouse demography in Mediterranean evergreen oak forests. We sampled 12 plots located in holm Quercus ilex and cork Q. suber oak, either thinned or not, in the winter-spring of 2000-2001 and 2001-2002. We measured vegetation structure and ground-level acorn availability in each plot and year. We trapped 294 wood mouse with a trapping effort of 2592 traps/night. Thinning significantly altered vegetation, reducing tree cover and increasing understory woody debris, especially in holm oak plots. Thinning also increased acorn biomass and quality in holm oak plots. In control plots, mouse abundance and reproductive effort were positively associated with acorn availability. However, this relationship was reversed in thinned plots, where abundance and reproductive activity were negatively correlated with food availability. This suggests that the positive effect of increased food was overcompensated by other negative effects of thinning, the latter increasing food resources but making mice more vulnerable to predation. Change in the food-risk trade-off precluded wood mouse populations to fully profit from increased food supply and may have also unbalanced the mutualist-antagonist conditional mutualism with oaks key for long-term tree recruitment.
Land snails are commonly associated with cool, moist environments, yet some species, such as Theba pisana, can persist in dry, hot habitats like coastal dunes. In the Pampean region of Argentina, this non-native species occurs in foredunes dominated by sparse native grasses as well as patches of invasive iceplants (Carpobrotus spp.). This study evaluated whether iceplant mats function as thermal refugia that enhance summer survival of T. pisana. Vertical temperature gradients, height distributions of dormant snails, survival at different heights, and behavioral responses to sand contact were compared between vegetation types. Microclimate monitoring showed that iceplant mats reduced near-ground temperatures compared to native grasses. Dormant snails in iceplants were found closer to the ground, and short-term survival was higher in these patches, particularly at lower heights. Snails detached and placed on sand beneath iceplants reattached to vegetation more quickly and with higher success. These results indicate that invasive Carpobrotus mats mitigate thermal stress and facilitate persistence of T. pisana in foredune habitats, exemplifying a case of non-native plant-mediated facilitation.
