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This paper reports a study of bioclimatic dynamics and land use in the region of Tlemcen (north-west of Algeria). GIS (geographic information system) and satellite images (LandSat) were used to conduct a diachronic study based on a series of satellite images from the years 2000 and 2019 to demonstrate changes in the study area while highlighting the importance of environmental conditions, including climate and anthropogenic impact on dynamic vegetation cover. Bioclimatic synthesis has shown an improvement in the rainfall regime and an evolution towards higher bioclimatic atmospheres between the two periods (1985–1999) and (2004–2018). Land use in the study area is under the influence of strong anthropogenic pressures and is experiencing a decline in forest areas from 28.74 to 17.49% but also in agricultural land and lawns from 38.61% to 27.67% in favour of built-up areas which increased from 0.81% to 1.09% but mainly to the benefit of bare soil: an ultimate stage of degradation whose surface area increased from 31.59% in 2000 to 53.46% in 2019. [ABSTRACT FROM AUTHOR]

Air pollution caused by tropospheric ozone contributes to the decline of forest ecosystems; for instance, sacred fir, Abies religiosa (Kunth) Schltdl. & Cham. forests in the peri-urban region of Mexico City. Individual trees within these forests exhibit variation in their response to ozone exposure, including the severity of visible symptoms in needles. Using RNA-Seq metatranscriptomic data and ITS2 metabarcoding, we investigated whether symptom variation correlates with the taxonomic and functional composition of fungal mycobiomes from needles collected in this highly polluted area in the surroundings of Mexico City. Our findings indicate that ozone-related symptoms do not significantly correlate with changes in the taxonomic composition of fungal mycobiomes. However, genes coding for 30 putative proteins were differentially expressed in the mycobiome of asymptomatic needles, including eight genes previously associated with resistance to oxidative stress. These results suggest that fungal communities likely play a role in mitigating the oxidative burst caused by tropospheric ozone in sacred fir. Our study illustrates the feasibility of using RNA-Seq data, accessible from global sequence repositories, for the characterization of fungal communities associated with plant tissues, including their gene expression. [ABSTRACT FROM AUTHOR]

Summary: Rising atmospheric carbon dioxide concentrations (CO2) and atmospheric nitrogen (N) deposition have contrasting effects on ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) symbioses, potentially mediating forest responses to environmental change.In this study, we evaluated the cumulative effects of historical environmental change on N concentrations and δ15N values in AM plants, EM plants, EM fungi, and saprotrophic fungi using herbarium specimens collected in Minnesota, USA from 1871 to 2016. To better understand mycorrhizal mediation of foliar δ15N, we also analyzed a subset of previously published foliar δ15N values from across the United States to parse the effects of N deposition and CO2 rise.Over the last century in Minnesota, N concentrations declined among all groups except saprotrophic fungi. δ15N also declined among all groups of plants and fungi; however, foliar δ15N declined less in EM plants than in AM plants. In the analysis of previously published foliar δ15N values, this slope difference between EM and AM plants was better explained by nitrogen deposition than by CO2 rise.Mycorrhizal type did not explain trajectories of plant N concentrations. Instead, plants and EM fungi exhibited similar declines in N concentrations, consistent with declining forest N status despite moderate levels of N deposition. [ABSTRACT FROM AUTHOR]

Forest decline and dieback are growing phenomena worldwide, resulting in severe, large‐scale degradation of the canopy. This can profoundly alter the provision of trophic resources and microhabitats for canopy‐dwelling arthropods.In 2019, we assessed the effect of oak decline on the community of canopy‐dwelling Hymenoptera. We selected 21 oak stands and 42 plots, located in three forests in France, presenting contrasting levels of decline. Insects were sampled at the canopy level with green multi‐funnel and flight‐interception traps.We collected a particularly diverse community of 19,289 insect individuals belonging to 918 taxa, 10 larval trophic guilds and 7 nesting guilds.Oak decline had no effect on the abundance or richness of the overall community but significantly reshaped the community assemblages. Decline had contrasting effects depending on the taxa and guilds considered. Specialist parasitoids were more abundant at intermediate levels of decline severity while generalists were negatively affected. Taxa depending on ground‐related resources and microhabitats were promoted. Saproxylic taxa were more abundant while xylophagous insects were negatively impacted.Reduced leaf area index promoted several guilds and the diversity of the overall community. While an increasing tree mortality rate enhanced the abundance and diversity of deadwood resources, it had negative impacts on several Hymenoptera guilds. Our results suggest that micro‐environmental changes at the ground level due to canopy decline have major cascading effects on the communities of canopy‐dwelling Hymenoptera.Our study highlights the relevance of studying Hymenoptera communities to investigate the outcomes of disturbances on forest biodiversity. [ABSTRACT FROM AUTHOR]

Summary: A specific, robust threshold for drought‐induced tree mortality is needed to improve the prediction of forest dieback. Here, we tested the relevance of continuous measurements of stem diameter variations for identifying such a threshold, their relationship with hydraulic and cellular damage mechanisms, and the influence of growth conditions on these relationships.Poplar saplings were grown under well‐watered, water‐limited, or light‐limited conditions and then submitted to a drought followed by rewatering. Stem diameter was continuously measured to investigate two parameters: the percentage loss of diameter (PLD) and the percentage of diameter recovery (DR) following rewatering. Water potentials, stomatal conductance, embolism, and electrolyte leakage were also measured, and light microscopy allowed investigating cell collapse induced by drought.The water release observed through loss of diameter occurred throughout the drought, regardless of growth conditions. Poplars did not recover from drought when PLD reached a threshold and this differed according to growth conditions but remained linked to cell resistance to damage and collapse.Our findings shed new light on the mechanisms of drought‐induced tree mortality and indicate that PLD could be a relevant indicator of drought‐induced tree mortality, regardless of the growth conditions. [ABSTRACT FROM AUTHOR]

An increased frequency and severity of droughts and heat waves have resulted in increased tree mortality and forest dieback across the world, but underlying mechanisms are poorly understood. We used a common garden experiment with 20 conifer tree species to quantify mortality after three consecutive hot, dry summers and tested whether mortality could be explained by putative underlying mechanisms, such as stem hydraulics and legacies affected by leaf life span and stem growth responses to previous droughts. Mortality varied from 0 to 79% across species and was not affected by hydraulic traits. Mortality increased with species' leaf life span probably because leaf damage caused crown dieback and contributed to carbon depletion and bark beetle damage. Mortality also increased with lower growth resilience, which may exacerbate the contribution of carbon depletion and bark beetle sensitivity to tree mortality. Our study highlights how ecological legacies at different time scales can explain tree mortality in response to hot, dry periods and climate change. [ABSTRACT FROM AUTHOR]

Mountain forests provide multiple benefits but are threatened by climate change-induced forest dieback. Although many studies summarize perceptions of forest ecosystem services, relatively few deal with mountain forests. The local population's perception of forest dieback in mountain forests in relation to climate change has rarely been investigated so far. Their perspective is relevant as local people are often deeply attached to "their" forests, they actively use forest ecosystems and—as voters and taxpayers—they need to support the state's adaptation and funding measures. Therefore, this study investigates the climate change and forest dieback perception of local inhabitants in two mountain areas of Southern Germany (the German Alps and the Bavarian Forest) with a quantitative survey based on representative online samples (n = 709). Relying conceptually on van der Linden's (J Environ Psychol 41:112–124, 2015. https://doi.org/10.1016/j.jenvp.2014.11.012) climate change risk perception model, the results show that experiential processing, cognitive and socio-cultural factors are related to locals' forest dieback and climate change perception, while socio-demographics show no or few connections. Nearly two-thirds (64.7%) of the respondents perceive moderate to strong forest dieback, while more than half (55.0%) of the respondents already observe consequences of climate change. The perceptions of climate change and forest dieback are positively correlated with medium to high strength. This shows that forest dieback could be interpreted as an indicator of climate change, which is difficult to observe due to its long-term nature. We identify three groups of respondents regarding preferred forest adaptation strategies to climate change. In general, respondents support nature-based forest adaptation strategies over intense measures. [ABSTRACT FROM AUTHOR]

There is persistent uncertainty about how integrated plant functions, like growth, are mechanistically constrained and practically predicted by functional traits. For trees, these knowledge gaps persist for two reasons: First, studies of 'natural' forests are observational, with highly variable and confounding resource limitation and competition; second, most studies investigate only a few popular traits and ignore context‐dependencies in trait effects on growth (e.g. trait–environment or trait–ontogeny interactions).We assessed 17 traits as predictors of radial growth and aboveground carbon sequestration for 182 trees, including individuals of 42 species common to temperate cities. By focusing exclusively on planted trees growing in isolation, our unique study is a pseudo‐experiment that spans a large range of taxonomic and trait variability, and minimizes confounding effects of environmental heterogeneity (e.g. shifts in light availability with tree size). Focal traits included not only commonly measured traits related to leaf economics and plant size, but also wood traits and whole‐plant phenology.Models with indices of tree ontogeny (size) and traits explained 80% and 72% of variability in relative growth and carbon sequestration, respectively, and traits accounted for ~20% of the variation. Traits related to said tree functions included leaf dry matter content (LDMC), leaf N content, mature height, wood anatomy and phenology. LDMC was positively correlated with wood growth and C sequestration across all size classes, while the positive effects of leaf N, mature height and wood density were only apparent for smaller trees. Ring‐porous species had higher rates of growth and C sequestration than diffuse‐porous species.Consistent with recent theory, growth rates of isolated, urban trees vary as function of simple and interactive effects of traits and size. Our findings are useful for optimizing reforestation efforts in temperate cities, where planners and land managers can select species for rapid growth and C sequestration using freely available data for the 'effect' traits we identified, including wood anatomy and density, leaf N, and LDMC. Lastly, the trait–growth relationships we describe here may reflect those of 'naturally' isolated trees growing in savannas and/or woodlands and provide an insightful frame of reference for trees in closed‐canopy forests. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Groundwater serves as the primary source of freshwater in arid and semi-arid regions, rendering them resilient against precipitation scarcity. Various aspects of the drought phenomenon necessitate the application of multivariate analysis and composite drought indices. These composite indices afford a more comprehensive understanding of various drought types. However, few studies have considered the integration of meteorological and groundwater drought information. This research delves into determining a threshold for triggering the transition from meteorological drought to groundwater drought in an arid region (Minab plain). It introduces the Joint Deficit Meteo-Groundwater Drought Index, a result of combining two droughts based on copula function. Furthermore, trivariate drought frequency analysis (severity-duration-peak) is conducted based on three scenarios in three clusters of the Minab Plain. Drought risk is then assessed using conditional probability. The results indicate that the northern and central parts of the Minab Plain face a high risk of meteo-groundwater drought. With increasing drought duration and severity, the peak also rises, placing the entire region at risk of widespread drought. A comprehensive understanding of meteo-groundwater drought and an assessment of its characteristics provide insights into the signals of propagation from meteorological drought to groundwater, facilitating the management of groundwater and surface water resources to mitigate the effects of drought. [ABSTRACT FROM AUTHOR]

Quantifying biodiversity trends in economically developed countries, where depopulation, associated secondary succession, and climate warming are ongoing, provides insights for global biodiversity conservation in the 21st century. However, few studies have assessed the impacts of secondary succession and climate warming on species' population trends at a national scale. We estimated the population trends of common breeding bird species in Japan and examined the associations between the overall population trend and species traits with the nationwide bird count data on 47 species collected from 2009 to 2020. The overall population trend varied among species. Four species populations increased moderately, 18 were stable, and 11 declined moderately. Population trends for 13 species were uncertain. The difference in overall trends among the species was associated with their habitat group and temperature niche. Species with relatively low‐temperature niches experienced more pronounced declines. Multispecies indicators showed a moderate increase in forest specialists and moderate declines in forest generalists (species that use both forests and open habitats) and open‐habitat specialists. Forest generalists and open‐habitat specialists also declined more rapidly at sites with more abandoned farmland. All species groups showed an accelerated decline or decelerated increase after 2015. These results suggest that common breeding birds in Japan are facing deteriorating trends as a result of nationwide changes in land use and climate. Future land‐use planning and policies should consider the benefits of passive rewilding for forest specialists and active restoration measures (e.g., low‐intensive forestry and agriculture) for nonforest specialists to effectively conserve biodiversity in the era of human depopulation and climate warming. [ABSTRACT FROM AUTHOR]

In recent years, restoration on former grassland sites has been widely encouraged globally, aiming to address the historical loss of 90% of ancient species‐rich grasslands, and to mitigate the associated threat to grassland biodiversity. The objective of our study was to investigate on a small‐scale how plant species spontaneously colonize restored grasslands. We inventoried 275 permanent plots twice (in 2019 and 2021) in a restored grassland, following the removal of a conifer plantation. Species richness and vegetation cover in surveyed plots were dependent on grazing activity and distance to adjacent grassland. Plant species associated with forest habitats declined, while the occurrence of generalist species together with a few grassland specialists generally increased. However, not all grassland specialists gained occurrence and the colonization pattern was not consistent over time, possibly due to the lack of continuous seed arrival and low livestock activity and hence lack of disturbance. These results suggest that successful colonization of plant species benefits from links to species‐rich sites adjacent to the restoration target, with spatial dispersal and improved conditions for species establishment being key to species occurrence. Both dispersal and establishment potential are likely facilitated through the presence of grazing livestock with access to both species‐rich grasslands and restoration targets. However, the shift towards a more typical grassland community takes place gradually, with vulnerable populations of early colonizing grassland species prone to local extinction in short‐term. As a result, continued functional connectivity provided by grazing animals is necessary to improve the diversity of the restored site and ensure the establishment of grassland specialists and to maintain the plant community composition. [ABSTRACT FROM AUTHOR]

Globally, animals that are range-restricted are frequently becoming species of conservation concern, in part due to competitive exclusion by phylogenetically and ecologically similar species that are more tolerant of human disturbance. However, climate and land use changes to natural landscapes can create pockets of refugia for range-restricted species. Western gray squirrels (Sciurus griseus) are native to the west coast of North America, principally California and western Oregon. Over the past several decades, Western Gray Squirrel populations have declined in human-dominated areas, with increased competition from introduced congeneric species native to eastern North America cited as a primary driver. Despite declines in their established range west of the Pacific Crest in western North America, western gray squirrels are extending their range into the Great Basin, where they were not historically found. Using a network of remote camera traps deployed across the Sierra Nevada–Great Basin ecotone in northwestern Nevada, we detected western gray squirrels across 16 of 100 camera-trapping sites. The majority of detections were located in piñon–juniper woodland, a land cover type not previously occupied by this species. Occupancy modeling revealed that western gray squirrels were equally likely to occur in piñon–juniper woodland compared to mature pine forest that they occupy elsewhere in their range. A species distribution model parameterized with historical gray squirrel observations (pre-1950), indicated increased climatic suitability for the species on the eastern side of the Sierra Nevada in recent decades, which may have facilitated this range expansion. Our findings reveal the potential for species declining in their historical range to colonize novel habitats that become increasingly suitable as a result of human-driven changes to ecosystems. [ABSTRACT FROM AUTHOR]

Tropical forest productivity represents an important global carbon sink, but many tropical forests grow on infertile soils. Efficient nutrient cycling by litterfall has long been assumed to maintain tropical tree growth, but there is no direct evidence that the nutrients cycled in litterfall are essential for tropical forest productivity.To test whether nutrient cycling by litterfall maintains tropical forest above‐ground productivity, we established large‐scale long‐term litter removal (L−) and litter addition (L+) treatments in a mature lowland tropical forest. We hypothesised that the removal of nutrients in litter would reduce tree growth, survival and litter production in L− plots. By contrast, the addition of nutrients in litter would enhance tree growth, survival and litter production in L+ plots. To test our hypotheses, we recorded tree growth and survival every 2 years, and measured litterfall monthly during 17 years of treatments.Tree growth and litterfall declined over time in L− plots, with consistently lower growth rates compared to controls after 8 years, and lower litter production after 4 years of treatments. By contrast, although litterfall was higher in the L+ plots relative to the controls, there was only a minor transient increase in tree growth immediately after the start of treatments. Tree survival declined over time in all treatments but was not affected by litter manipulation.The long‐term decline in tree growth and litterfall in the L− plots provides the first empirical evidence that nutrient cycling by litterfall plays a key role in maintaining above‐ground productivity in this tropical forest. By contrast, the transient increase in growth in the L+ plots can be attributed to the large inputs of nutrients with the addition of the entire litter standing crop at the start of treatments. The addition of nutrients in litter over the long term was nonetheless sufficient to enhance litter production, possibly by accelerating leaf turnover.Synthesis: Efficient nutrient cycling by litterfall makes an important contribution to the annual nutrient requirements of mature tropical forest trees, compensating for infertile soils. Disturbances that disrupt this finely balanced cycle could therefore reduce biomass carbon sequestration in tropical forests. [ABSTRACT FROM AUTHOR]

Tree mortality and forest dieback episodes are increasing due to drought and heat stress. Nevertheless, a comprehensive understanding of mechanisms enabling trees to withstand and survive droughts remains lacking. Our study investigated basal area increment (BAI), and δ13C-derived intrinsic water-use-efficiency (iWUE), to elucidate beech resilience across four healthy stands in Italy with varying climates and soil water availability. Additionally, fist-order autocorrelation (AR1) analysis was performed to detect early warning signals for potential tree dieback risks during extreme drought events. Results reveal a negative link between BAI and vapour pressure deficit (VPD), especially in southern latitudes. After the 2003 drought, BAI decreased at the northern site, with an increase in δ13C and iWUE, indicating conservative water-use. Conversely, the southern sites showed increased BAI and iWUE, likely influenced by rising CO2 and improved water availability. In contrast, the central site sustained higher transpiration rates due to higher soil water holding capacity (SWHC). Despite varied responses, most sites exhibited reduced resilience to future extreme events, indicated by increased AR1. Temperature significantly affected beech iWUE and BAI in northern Italy, while VPD strongly influenced the southern latitudes. The observed increase in BAI and iWUE in southern regions might be attributed to an acclimation response. [ABSTRACT FROM AUTHOR]

Radiocarbon ages for samples of organic material within and overlying the highest Holocene floodplain and fan terraces in Glen Feshie and Glen Tromie imply sediment aggradation after ∼4.3 cal ka and probably incision after ∼3.7 cal ka, and in the Edendon Valley aggradation after ∼2.8 cal ka, with incision after ∼2.7 cal ka. The timing of sediment aggradation at all three sites postdates the onset of pine forest decline (∼4.8 cal ka) at nearby high-level sites, and coincides with wet periods characterised by high water tables. This coincidence in timing suggests that forest decline may have caused upstream extension of the tributary network, headwater incision and flashier flood responses, and that increased rainfall enhanced sediment discharge from headwater tributaries, with consequent sediment accumulation downstream on low-gradient fans and floodplains. More speculatively, exhaustion of readily entrained sediment from headwater areas may have stimulated subsequent floodplain and fan incision. Our results show that the highest Holocene terrace (the Main Holocene Terrace) is a diachronous feature, even in valleys emanating from the same upland source area, and support the conclusions of simulation models that predict marked increases in sediment discharge when deforestation is succeeded by an episode of increased rainfall. [ABSTRACT FROM AUTHOR]

The drought resilience of forest ecosystems is generally believed to depend on the dominant tree species' hydraulic traits. These traits define the maximum water transport capacity and the degree of vulnerability to hydraulic failure of a tree species. This work evaluates the effect of the intraspecific variability of hydraulic traits on the simulated tree water use in the Community Land Model (CLM, version 5.0). We selected two contrasting broadleaved tree species and performed a series of numerical experiments by modifying the parameters of the plant vulnerability curve and the maximum xylem hydraulic conductance accounting for the variability within each species. Our prescribed parameter sets represent vulnerable and resistant tree responses to the water deficit. At sites with an ample water supply, the resistant configuration simulates reduced water stress and increased transpiration compared to the vulnerable configuration. Meanwhile, the model results are counter‐intuitive at temporarily dry sites when water availability is the limiting factor. The numerical experiments demonstrate the emergent role of the maximum xylem conductance as a modulator of the plant water use strategy and the simulated transpiration within the model. Using the default value for maximum xylem conductance, the model tends to overestimate the early summer transpiration at drier sites, forcing the vegetation to experience unrealistic water stress later in the year. Our findings suggest that the parameterization of maximum xylem conductance is an important yet unresolved problem in the CLM and similar land surface models. Plain Language Summary: The survival of trees in drought conditions depends on their ability to adapt to water scarcity. Part of this adaptation is characterized by specific plant traits, which are an important component of Land Surface Models and largely determine the relationship between soil moisture and canopy gas exchange. Our study explores how the variability of specific plant traits of individual tree species may affect the selected model's ability to reproduce the water use observed in forest stands in Europe. For climates with a pronounced summer dry period, we found that the default model settings overestimated the vegetation water use in the early growing season, when water is abundant, resulting in severe water stress and underestimated transpiration as the dry season progressed. We specifically demonstrate that a rarely considered plant trait, representing the maximum water transport capacity, plays an essential role in controlling the magnitude of simulated water use and that adjustments to this parameter greatly help to reproduce the vegetation water use observed in seasonally dry climates. Key Points: We explore the impact of the intraspecific variability of plant hydraulic traits on the simulated transpiration by Community Land Model 5.0We find that a choice of plant hydraulic traits that reproduces observed plant transpiration also reduces simulated water stressWe demonstrate the critical role of the maximum xylem conductance in the model and its dependency on factors other than vegetation type [ABSTRACT FROM AUTHOR]

Subalpine forests worldwide face the synergistic threats of global warming and increased biotic attack, and the collapse or transition of subalpine forests is predicted in south‐eastern Australia under future climates. The recent widespread dieback of subalpine snow‐gum forests due to increased activity of a native wood‐boring longicorn beetle, Phoracantha mastersii, suggests this process may already be underway. We investigated how variation in tree tissue traits and environmental conditions correlated with elevation‐dependent spatial patterns of forest mortality. We hypothesized that increased vulnerability of subalpine snow gums to wood‐borer‐mediated dieback at intermediate elevations was associated with poorly resolved differences in traits between montane (Eucalyptus pauciflora subsp. pauciflora) and subalpine (E. pauciflora subsp. niphophila) snow‐gum subspecies. We first sought to characterize variation and elevation‐dependent transitions in 20 structural and drought‐related functional traits among 120 healthy trees distributed along a 1000 m elevation transect that spanned the subspecies transition zone. Secondly, we surveyed 774 trees across 53 sites between 1280 and 1980 m a.s.l. to explore associations between borer‐damage severity, elevation, subspecies and a subset of traits that differed between subspecies. We observed evidence for both continuous trait variation in response to changing elevation (10/20 traits) and discrete shifts in mean trait values across the transition between subspecies distributions (5/20 traits). Increased borer‐damage severity across the montane‐to‐subalpine subspecies transition was correlated with lower bark thickness, whereas reduced borer damage at the highest elevations was associated with greater precipitation and lower temperatures. Our results suggest that due to possessing distinct traits associated with increased borer susceptibility, subalpine snow‐gum forests may be subject to an increased risk of severe borer‐mediated forest dieback under warmer and drier future climates. Identifying traits contributing to species' distribution limits and biotic‐agent vulnerability remains critical for predicting, monitoring and possibly mitigating forest and vegetation declines under future climates. [ABSTRACT FROM AUTHOR]

Removal of predators and creation of early seral habitat have, in many systems, caused substantial population growth of herbivores. Hyperabundant herbivores, in turn, induce cascading ecosystem effects, but few studies have investigated long-term browser density trends in relation to succession and stochastic climate events. Here, we use annual, empirical population estimates of a forest browser to relate forest succession to long-term decline of an herbivore that prefers early seral habitat. From 2007–2021, concurrent with reduced timber harvest, we used line-transect distance sampling to document annual changes in Columbian black-tailed deer (Odocoileus hemionus columbianus) density on a mid-sized (17.3km2) predator-free island. We documented successional changes associated with forest aggradation and decreased forage quality for deer: early successional shrub/scrub habitat declined 3.8%/year; timber volume increased 4.5%/year; and canopy coverage increased 2.5%. In 2007–2008, deer densities were the greatest observed (~44/km2), but then an historic snowstorm reduced deer density by 39%. From 2010–2021, as forests continued to mature, deer density decreased 4.0%/year, declining to 20 deer/km2. Using a multivariate approach to combine habitat variables (i.e., early seral coverage, timber volume, and canopy closure) into a measure of forest maturation, we found a significant negative relationship between deer density and forest aggradation. Thus, consistent with predictions for bottom-up limited browsers, we observed significant annual declines in a deer population throughout an extended period of forest regrowth. Despite declines, deer density on the island exceeds mainland densities, and overbrowsing likely continues to disrupt ecosystem processes. [ABSTRACT FROM AUTHOR]

The Zagros oak forests in Iran are facing a concerning decline due to prolonged and severe drought conditions over several decades, compounded by the simultaneous impact of temperature on oak populations. This study in oak woodlands of central Zagros forests in Lorestan province analyzed abiotic factors such as climate properties, topographic features, land use, and soil properties from 1958 to 2022. We found that higher elevation areas with steeper slopes and diverse topography show significant potential for enhancing oak tree resilience in the face of climate change. Additionally, traditional land use practices like livestock keeping and dryland farming contribute to a widespread decline in oak populations. Preserving forest biodiversity and ensuring ecological sustainability requires immediate attention. Implementing effective land-use management strategies, such as protecting and regulating human-forest interaction, and considering meteorological factors to address this issue is crucial. Collaborative efforts from stakeholders, policymakers, and local communities are essential to oppose destructive suburban sprawl and other developments. Sustainable forestry practices should be implemented to improve the living standards of local communities that rely on forests and traditional livestock keeping, offer forestry-related jobs, and ensure social security. Such efforts are necessary to promote conservation awareness and sustainable practices, safeguarding this unique and vital ecosystem for future generations. [ABSTRACT FROM AUTHOR]

Urbanisation is rapidly altering ecosystems, leading to profound biodiversity loss. To mitigate these effects, we need a better understanding of how urbanisation impacts dispersal and reproduction. Two contrasting population demographic models have been proposed that predict that urbanisation either promotes (facilitation model) or constrains (fragmentation model) gene flow and genetic diversity. Which of these models prevails likely depends on the strength of selection on specific phenotypic traits that influence dispersal, survival, or reproduction. Here, we a priori examined the genomic impact of urbanisation on the Neotropical túngara frog (Engystomops pustulosus), a species known to adapt its reproductive traits to urban selective pressures. Using whole‐genome resequencing for multiple urban and forest populations we examined genomic diversity, population connectivity and demographic history. Contrary to both the fragmentation and facilitation models, urban populations did not exhibit substantial changes in genomic diversity or differentiation compared with forest populations, and genomic variation was best explained by geographic distance rather than environmental factors. Adopting an a posteriori approach, we additionally found both urban and forest populations to have undergone population declines. The timing of these declines appears to coincide with extensive human activity around the Panama Canal during the last few centuries rather than recent urbanisation. Our study highlights the long‐lasting legacy of past anthropogenic disturbances in the genome and the importance of considering the historical context in urban evolution studies as anthropogenic effects may be extensive and impact nonurban areas on both recent and older timescales. [ABSTRACT FROM AUTHOR]

While some South American primates are well-studied, many are poorly known to science. This makes reports of their ecology very valuable, especially when the region inhabited is threatened by human activities. We combined data from three independent field studies to provide a better understanding of the behavior, ecology, chemical composition of plant items consumed, and conservation of the Parecis Plateau titi monkey (Plecturocebus parecis), a recently described species from the southern Amazonian Arc of Deforestation. Specifically, we collected behavioral data for eight groups over 8 months and quantified the monkeys' activity budget. To analyze the chemical compounds in the plants eaten, we used vanillin to determine condensed tannin and alkaline precipitation to quantify total alkaloid content. We also determined the extent of forest loss and fragmentation from 2000 to 2019 within the known range of the Parecis Plateau titi monkey using satellite imagery. We found that group size ranged 2–6 individuals, and the monkeys spent 31% of the day foraging, 22% resting, 19% feeding, 14% moving, and 14% in other activities. The monkeys ate 50 plant species from 24 families and appeared to be unusually tolerant of dietary tannins but avoided alkaloids. Habitat modification within the species' range has been extensive: forest cover declined by 16.1% in 2000–2019; the largest areas of continuous forest were reduced by 37.5%; mean fragment size decreased 67.5% (from 421.0–136.9 ha). Forest loss and fragmentation were most significant in the northern half of the species' range and its southern border. Given the Parecis Plateau titi monkey's tolerance for toxic dietary species, the intense modification of its geographic range, and its capacity to live in fragmented habitats, we recommend that future studies investigate these topics across all 37 species of titi monkeys. In addition, recordings of vocal repertoires will improve field surveys and help with population estimates, especially for titi monkey species living in geographic regions that have been heavily modified by humans. [ABSTRACT FROM AUTHOR]

The intensity, duration, and severity of drought increasing across the American Southwest. Plant restoration efforts are often thwarted by drought‐induced effects (i.e. drought‐induced mortality or failure to reproduce). Careful selection of plant materials to match future environmental conditions could improve restoration success under climate change. Here, we focus on Plantago patagonica, a priority arid land restoration species in the southwestern US. Using experimental drought in a greenhouse and supplemental watering in a common garden experiment, we quantified how the seed‐collection site environment influenced plant growth, performance, phenotypic plasticity, and evidence of local adaptation in 12 populations of P. patagonica. In the greenhouse, we found plants from hotter and drier environments had higher root:shoot ratios, while those from more variable precipitation regimes had greater total biomass in response to drought. Populations sourced from warmer environments exhibited sevenfold greater plasticity in root:shoot ratio compared to those from cooler environments, and there was strong evidence for local adaptation in phenology, as populations sourced from geographic locations nearer the common garden exhibited five times more flowering individuals than those sourced furthest from that garden. In the common garden, we found that plants sourced from wetter locations and those with more consistent precipitation regimes had lower mortality and higher specific leaf area, a proxy for growth, under unwatered ambient conditions. These results suggest plant performance of P. patagonica under reduced water availability is strongly shaped by the seed‐collection site environment and may be a useful tool for improving restoration outcomes in a changing world. [ABSTRACT FROM AUTHOR]

The primary aim of this study is to determine the Middle-Late Holocene vegetation history of the İğneada Longoz (Floodplain) Forests around Lake Mert, located in Kırklareli, using high-resolution palynological analysis conducted on the MRT-04 core. Pollen analyses was performed on sediment samples collected from 67 different levels within the core. Pollen counting and identification were performed using a Leica DM750 light microscope, with a minimum of 500 terrestrial pollen grains counted per sample. The age of the lake was determined to be 6600 years old through radiocarbon dating of the core. According to the findings from the pollen analysis, deciduous mixed oak forests have dominated the region in and around Lake Mert for the past 6600 years. Within these mixed oak forests, Quercus cerris type (deciduous oaks) is predominant, with notable contributions from Fagus , Carpinus , Corylus , and Tilia. This forest composition has displayed a consistent pattern, except for changes attributed to the expansion of temperate species and human influences. The distribution of mixed oak forests began to decline around 1360 BP, coinciding with a significant increase in the presence of Alnus , Fraxinus , and Ulmus. These trees are characteristic species of floodplain forest and indicate the initiation of the formation of the İğneada Longoz Forests after 1360 BP. Furthermore, around 420 BP, there was a substantial decrease in the pollen percentages of Quercus and Fagus. During this period of declining mixed oak forests, Plantago and Ambrosia appeared for the first time in the pollen diagram. The reduction in arboreal plant taxa and the rise of herbaceous taxa such as Plantago , Ambrosia , and Poaceae, which serve as indicators of human impact, signify the conversion of forested areas into agricultural and pasture lands. [ABSTRACT FROM AUTHOR]

Background: We analyze the forest carbon stock development following the recent historically unprecedented dieback of coniferous stands in the Czech Republic. The drought-induced bark-beetle infestation resulted in record-high sanitary logging and total harvest more than doubled from the previous period. It turned Czech forestry from a long-term carbon sink offsetting about 6% of the country's greenhouse gas emissions since 1990 to a significant source of CO2 emissions in recent years (2018–2021). In 2020, the forestry sector contributed nearly 10% to the country's overall GHG emissions. Using the nationally calibrated Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) at a regional (NUTS3) spatial resolution, we analyzed four scenarios of forest carbon stock development until 2070. Two critical points arise: the short-term prognosis for reducing current emissions from forestry and the implementation of adaptive forest management focused on tree species change and sustained carbon accumulation. Results: This study used four different spruce forest dieback scenarios to assess the impact of adaptive forest management on the forest carbon stock change and CO2 emissions, tree species composition, harvest possibilities, and forest structure in response to the recent unprecedented calamitous dieback in the Czech Republic. The model analysis indicates that Czech forestry may stabilize by 2025 Subsequently, it may become a sustained sink of about 3 Mt CO2 eq./year (excluding the contribution of harvested wood products), while enhancing forest resilience by the gradual implementation of adaptation measures. The speed of adaptation is linked to harvest intensity and severity of the current calamity. Under the pessimistic Black scenario, the proportion of spruce stands declines from the current 43–20% by 2070, in favor of more suited tree species such as fir and broadleaves. These species would also constitute over 50% of the harvest potential, increasingly contributing to harvest levels like those generated by Czech forestry prior to the current calamity. The standing stock would only be recovered in 50 years under the optimistic Green scenario. Conclusion: The results show progress of adaptive management by implementing tree species change and quantify the expected harvest and mitigation potential in Czech forestry until 2070. [ABSTRACT FROM AUTHOR]

Exploring sustainable strategies for improving crop water and nitrogen use efficiency is essential. Silicon (Si) has been reported as a beneficial metalloid for plants since it alleviates several abiotic stresses (including drought) by triggering the plants' antioxidant system. However, its role in mitigating the negative impact of nitrogen (N) deficit alone or when combined with water (W) deficit is not well studied. This study applied 0 or 2 mM of Na₂SiO3 to 3‐week‐old tomato cv. Micro‐Tom seedlings that were grown under the following conditions: control (CTR; 100%N + 100% Field Capacity), N deficit (N; 50% N + 100% Field Capacity), water deficit (W; 100% N + 50% Field Capacity) or combined stress (N + W; 50% N + 50% Field Capacity). The Si effect on tomato plant growth depended on the type of stress. Si could only alleviate stress caused by N + W deficit resulting in a higher root dry weight (by 28%), total dry weight (by 23%) and root length (by 37%). Alongside this, there was an increase in the antioxidant (AOX) system activity with the root activity of ascorbate peroxidase and catalase enzymes being enhanced by 48% and by 263%, respectively. Si application also enhanced AOX enzyme activity when tomato plants were subjected to individual deficits but to a lesser extent. In conclusion, Si‐treated tomato plants could efficiently modulate their AOX networks in a situation of combined N and water limitation, thus mitigating some of the adverse effects of this combined stress. [ABSTRACT FROM AUTHOR]

Forest decline caused by climate change has been a growing challenge for European foresters for decades. The accumulation of tree-related microhabitats (TreMs) and deadwood during decline can enhance stand structural heterogeneity and provide crucial habitat features for many forest ecological guilds. We analysed changes in deadwood and TreM assemblages using a trait-based approach in three case studies: drought-induced decline in highland Pyrenean fir and lowland oak forests, and windstorm/pest-induced dieback in highland Bavarian spruce forests. Decline caused significant changes in deadwood and TreM characteristics and composition in three forest contexts. However, tree density with cavities, exudates, or crown deadwood was not linked to decline intensity. Declining conifer forests had more large deadwood and downed woody debris, and their TreM assemblages were more saproxylic, less epixylic, and included more cracks and exposed sapwood. TreM assemblages in drought-declining forests had higher diversity, functional richness, and more dead tops than healthy stands. In Bavarian spruce forests, there was more decayed downed deadwood, and the TreM assemblages were more associated with the base of the tree, snags, and logs. Overall, forest decline significantly boosts ecological niche resources, typically scarce in managed forests, which could benefit many forest biodiversity groups. Though post-disturbance management should respect tree species-dependent economic balance and avoid phytosanitary risks, it should also consider the ecological benefits of decline-induced heterogeneity. [ABSTRACT FROM AUTHOR]

Background and Aims Kelps are the primary foundation species in temperate subtidal rocky shores worldwide. However, global change is causing their decline with consequences for the organisms that rely on them. An accurate assessment of these consequences may depend on which attributes of the associated community are considered. This study shows that conventional α-diversity approaches may overlook some of these consequences compared to spatially explicit approaches such as with β-diversity. Methods A 1-year seasonal study was conducted to compare the macroalgal understorey between healthy reefs with a Laminaria ochroleuca canopy and degraded reefs where the canopy collapsed years ago due to excessive fish herbivory. At each reef, the understorey seaweed assemblage was recorded in five replicate quadrats to estimate α-diversity (total richness, species density, Shannon index) and β-diversity (intra- and inter-reef scale). Key Results The understorey assemblage exhibited a distinct seasonal dynamic in both healthy and degraded reefs. α-Diversity attributes increased in spring and summer; turf-forming algae were particularly dominant in degraded reefs during summer. β-Diversity also showed seasonal variability, but mostly due to the changes in degraded reefs. None of the α-diversity estimates differed significantly between healthy and degraded reefs. In contrast, spatial β-diversity was significantly lower in degraded reefs. Conclusions Although the loss of the kelp canopy affected the composition of the macroalgal understorey, none of the conventional indicators of α-diversity detected significant differences between healthy and degraded reefs. In contrast, small-scale spatial β-diversity decreased significantly as a result of deforestation, suggesting that the loss of kelp canopy may not significantly affect the number of species but still have an effect on their spatial arrangement. Our results suggest that small-scale β-diversity may be a good proxy for a more comprehensive assessment of the consequences of kelp forest decline. [ABSTRACT FROM AUTHOR]

In recent years, Togo's protected areas have been subject to a worrying process of anthropisation. This has led to a decline in forest ecosystems, their biodiversity and their functions. The general objective of this study is to assess the state of conservation of the classified forest of Amou-Mono between 1986 and 2021. More specifically, it aims to: (i) characterize the dynamics of land use from 1986, 2000, 2013 and 2021 and, (ii) assess the impact of changes in land use on the potential for carbon sequestration. A multi-date classification of Landsat images for the years 1986, 2000, 2013 and 2021 made it possible to quantify and assess changes in occupation. The dynamics of land use between 1986 and 2021 is mainly reflected by a regression of dense/riparian forests (81.40%) and open forests/wooded savannahs (67.79%) and the progression of wooded/shrubby Savannah (172.93%). Anthropogenic formations: Fields/fallow and Agglomerations/Bare soils, absent in 1986, occupy in 2021 respective proportions of 38.1 % and 2.19%. Human activities, particularly logging and agricultural clearing, are causing fragmentation and regression of forest ecosystems. Unless action is taken to reverse the trend, the conservation of biodiversity and ecosystem functions in this classified forest will be increasingly threatened. [ABSTRACT FROM AUTHOR]

Aim: Forest dieback is increasing from unfavourable climate conditions. Western redcedar (WRC)—a culturally, ecologically and economically important species—has recently experienced anomalously high mortality rates and partial canopy dieback. We investigated how WRC tree growth and dieback responded to climate variability and drought using tree‐ring methods. Location: Pacific Northwest, USA. Taxon: Western redcedar (Thuja plicata). Methods: We collected tree cores from three tree health status groups (no canopy dieback, partial canopy dieback, and dead trees) at 11 sites in coastal (maritime climate) and interior (continental climate) WRC populations. From growth rates, we computed four growth indices that assessed the resilience to drought and estimated the year of death. Results: Warmer and drier climate conditions in May/June that extended the annual July‐to‐September dry season reduced radial growth in 9 of 11 sites (1975–2020). WRC trees recovered growth to pre‐drought rates within 3 years when post‐drought climate conditions were cooler/wetter than average. However, recovery from drought was slower or absent when warmer/drier conditions occurred during the post‐drought recovery period, possibly leading to the recent and widespread mortality across the coastal population. WRC mortality was portended by 4–5 years of declining growth. Annually‐resolved mortality in coastal populations predominately occurred in 2017–2018 (80% of sampled dead trees), a period that coincided with exceedingly hot temperatures and the longest regionally dry period from May to September (1970–2020). In interior populations, mortality was dispersed among years but associated with warmer and drier conditions from August to September. Main conclusions: Our findings forewarn that a warming climate and more frequent and severe summer droughts, especially in consecutive years, will likely increase the vulnerability of WRC to canopy dieback and mortality and possibly other drought‐sensitive trees in one of the world's largest forest carbon sinks. [ABSTRACT FROM AUTHOR]

Anthropogenically driven environmental changes over recent centuries have led to severe declines of wildlife populations. Better tools are needed to assess the magnitude and consequences of these declines. Anecdotal evidence suggests European bat populations have suffered substantial declines in the past centuries. However, there is little empirical evidence of these declines that can be used to put more recent population trends into historic context.This study is a collaboration between academics and conservation practitioners to develop molecular approaches capable of providing evidence of historic population changes that can inform conservation status assessments and management. We generated a genomic dataset of 46,872 SNPs for the Western barbastelle, Barbastella barbastellus, a regionally Vulnerable bat species, including colonies from across the species' British and Iberian ranges. We used a combination of landscape genetics and model‐based inference of demographic history to identify both evidence of population size changes and possible drivers of these changes.Levels of genetic diversity increased and inbreeding decreased with increasing broadleaf woodland cover around the colony. Genetic connectivity was impeded by artificial lights and facilitated by rivers and broadleaf woodland cover.The demographic history analysis showed that both the northern and southern British barbastelle populations have declined by 99% over the past 330–548 years. These declines may be linked to the loss of large oak trees and native woodlands due to shipbuilding during the early colonial period.Synthesis and applications. Genomic approaches can provide a better understanding of the conservation status of threatened species, within historic and contemporary contexts, and inform their conservation management. Our findings of will directly influence the definition of the Favourable Conservation Status of the barbastelle, in turn influencing considerations of the conservation of the species in development plans. Knowledge gained will also help set species recovery targets. Policymakers are interested in using our approach for other species. This study shows how we can bridge the implementation gap between genomic research and direct conservation applications. There is an urgent need to carry out such collaborative studies for other priority species to enable informed species recovery interventions via policy mechanisms and project delivery. [ABSTRACT FROM AUTHOR]

Recent observation-based studies suggest that the Amazon rain forest has lost substantial resilience since 1990, indicating that the forest might undergo a critical transition in the near future due to global warming and deforestation. The idea is to use trends in lag-1 auto-correlation of leaf density as an early warning signal of an imminent critical threshold for rain forest dieback. Here we test whether the observed change in auto-correlations could arise from internal variability by using historical and control simulations of nine sixth-generation Earth system model ensembles (Phase 6 of the Coupled Model Intercomparison Project, CMIP6). We quantify trends in leaf area index auto-correlation from both models and satellite observed vegetation optical depth from 1990 to 2017. Four models reproduce the observed trend with at least one historical realization, whereby the observations lie at the upper limit of model variability. Three out of these four models exhibit similar behavior in control runs, suggesting that historical forcing is not necessary for simulating the observed trends. Furthermore, we do not observe a critical transition in any future runs under the strongest greenhouse gas emission scenario (SSP5-8.5) until 2100 in the four models that best reproduce the past observed trends. Hence, the currently observed trends could be caused simply by internal variability, and, unless the data records are extended, have limited applicability as an early warning signal. Our results suggest that the current rapid decline in Amazon rain forest coverage is mainly caused by local actors. [ABSTRACT FROM AUTHOR]

Changing climate and growing human impacts are resulting in globally rising temperatures and the widespread loss of habitats. How species will adapt to these changes is not well understood. The Northern Goshawk (Accipiter gentilis) can be found across the Holarctic but is coming under more intense pressure in many places. Studies of recent populations in Finland and Denmark have shown a marked decline in body size of Northern Goshawks over the past century. Here we investigate long‐term changes to Norwegian populations of Northern Goshawk by including material from the Middle Ages. We measured 240 skeletons of modern Northern Goshawks from Norway, Sweden, Denmark and Finland, and 89 Medieval Goshawk bones. Our results show that Norwegian and Swedish female Goshawks have decreased in size over the past century, whilst males showed little decline. Medieval female Goshawks were larger than contemporary females. A decline in forest habitats and a concomitant shift towards smaller prey likely drove a shift to smaller body size in Northern Goshawks. Our study shows that significant body size changes in birds can occur over relatively short time spans in response to environmental factors, and that these effects can sometimes differ between sexes. [ABSTRACT FROM AUTHOR]

Soil respiration (Rs) is the largest outward flux of carbon (C) from terrestrial ecosystems, accounting for more than half of total temperate forest C loss. Evaluating the drivers of this globally important flux, as well as identifying autotrophic (Ra) and heterotrophic (Rh) responses, is critical in the era of rapid global change because small changes could result in disproportionally large impacts to ecosystem C balance. We assessed four years of Rs and Rh from the Forest Resilience Threshold Experiment (FoRTE) to better understand how soil C fluxes respond to a disturbance simulating phloem-disrupting insects. This replicated experiment spanning multiple landscape ecosystems contains four disturbance severities of 0, 45, 65 and 85% gross defoliation as well as two disturbance types targeting the upper and lower canopy. We found an immediate and sustained decline in Rs following phloem disruption that persisted for three years and was proportional to severity. Proportional declines in basal soil respiration and fine-root production with increasing disturbance severity and stable Rh lead us to conclude that Ra drove the suppression of Rs into the third year following disturbance. These responses were conserved across four landscape ecosystems, suggesting the mechanisms causing Rs to decline following phloem disruption were similar despite large differences in composition and productivity. The 3-year reduction of C losses through Rs and, contrastingly, sustained C storage through wood production suggests ecosystem C balance may have remained relatively stable in the first few years following disturbance, even at the highest severity. [ABSTRACT FROM AUTHOR]

Forest discourses help identify forest-related issues. They aim to aid policy and decision-makers in understanding forest-related challenges and opportunities better so that they may initiate possible strategies and tactics to tackle them. Ideally, information requirements for the forest discourses would be translated into measurable variables, being the basis for collecting, analysing, and reporting data and information. Our study examined the connection between major international forest reporting processes and forest discourses. We analysed summaries and key findings for policy makers of five recent major forest reports. We compared their focus with forest discourses on climate change, forest conservation, deforestation, forest decline, illegal logging, industrial forestry/bioeconomy, traditional knowledge, woody biomass production, and innovative wood-based biofuels. The paper explores how the forest discourses are reflected in the surveyed documents and closely examines the specific focus areas in the summaries for policy makers. The results show that most forest discourses are generally well-represented, albeit with different foci. The discourse on illegal logging could not be identified in any investigated documents, even though it remains a significant concern for international forest policy. Keywords related to traditional knowledge and woody biomass production could not be found in two of the analysed findings. All analysed summaries and key findings mention issues related to the climate change discourse topic. However, they lack information on emissions from deforestation, carbon dioxide emissions and carbon budgets, which are high in political discussions. The paper highlights how discourse issues have gained in complexity both topic-wise and regarding the reporting obligations, as policy and decisionmakers require more timely and comprehensive information about the status' and trends of forests. [ABSTRACT FROM AUTHOR]

Understanding the impact of human behaviour is crucial for successful mitigation of climate change across the globe. To shed light onto this issue, here we couple the forest dieback model with human behaviours. Using evolutionary game theory, we build a time-delay system where forest growth is impacted by both temperature and human mitigation choices, the latter being informed by temperature forecasts. Simulations of the coupled system over 200 years show us the varying outcomes: forest dies out and no one is a mitigator, forest dies out and everyone is a mitigator, or the forest survives and everyone is a mitigator. There exist rare cases where no one is a mitigator and yet the forest survives, but with a low coverage. We also find occasional oscillations where the proportion of mitigators vary between 0 and 1. Our results are based on simple models but have profound insights into determinants of behaviour changes desired in social-climate dynamics. [ABSTRACT FROM AUTHOR]

Atmospheric environmental assessment has emerged as a prominent area of research due to global climate change and regional atmospheric pollution issues. Accurate evaluation of atmospheric environmental vulnerability characteristics and understanding driving mechanisms are crucial for effective air pollution monitoring and prevention. This study focuses on the Pearl River Delta (PRD) region and employs the Vulnerability-Scoping-Diagram (VSD) model framework to establish an index system for assessing atmospheric environmental vulnerability based on exposure, sensitivity, and adaptability, combining the entropy value method and adopts Geographic Information System (GIS) for the time change and spatial evolution analysis, and finally utilizing the factor detection and interaction in Geodetector to explore the contribution degree of each driving factor of atmospheric environmental vulnerability and the exchange of influencing factors. The findings of this research are as follows: Firstly, the sensitivity index and resilience index of the atmospheric environment of the PRD exhibit an overall upward trend with fluctuations, while the exposure index demonstrates a pattern of initial increase, followed by a decrease, and subsequent increase with significant interannual variability. Secondly, the atmospheric environment vulnerability level of the PRD is primarily categorized as low and mild, with a negligible proportion of moderate vulnerability and no instances of severe or extreme vulnerability. The vulnerability index shows an initial increase followed by a subsequent decline from 2016 to 2020, indicating an overall improvement in the region's atmospheric environment. Thirdly, notable variations exist in the atmospheric environment vulnerability indices among the nine cities in the PRD, in which moderate vulnerability and low vulnerability are mainly concentrated in Guangzhou, Shenzhen, Foshan, and Dongguan in the central part of the PRD. lower vulnerability is primarily observed in the eastern and western regions of the PRD characterized by favorable natural environments and limited human interference, such as Huizhou, Zhaoqing, and Zhuhai. Finally, the atmospheric environment vulnerability of the PRD is the result of the combined effect of various driving factors, among which the urban built-up area, PM2.5 concentration, SO2 concentration, population density and the share of tertiary industry in GDP are the key drivers. [ABSTRACT FROM AUTHOR]

Previous work indicates that tropical forest can exist as an alternative stable state to savanna. Therefore, perturbation by climate change or human impact may lead to crossing of a tipping point beyond which there is rapid forest dieback that is not easily reversed. A hypothesized mechanism for such bistability is feedback between fire and vegetation, where fire spreads as a contagion process on grass patches. Theoretical models have largely implemented this mechanism implicitly, by assuming a threshold dependence of fire spread on flammable vegetation. Here, we show how the nonlinear dynamics and bistability emerge spontaneously, without assuming equations or thresholds for fire spread. We find that the forest geometry causes the nonlinearity that induces bistability. We demonstrate this in three steps. First, we model forest and fire as interacting contagion processes on grass patches, showing that spatial structure emerges due to two counteracting effects on the forest perimeter: forest expansion by dispersal and forest erosion by fires originating in adjacent grassland. Then, we derive a landscape-scale balance equation in which these two effects link forest geometry and dynamics: Forest expands proportionally to its perimeter, while it shrinks proportionally to its perimeter weighted by adjacent grassland area. Finally, we show that these perimeter quantities introduce nonlinearity in our balance equation and lead to bistability. Relying on the link between structure and dynamics, we propose a forest resilience indicator that could be used for targeted conservation or restoration. [ABSTRACT FROM AUTHOR]

Climate change is increasing the frequency of extreme fires. In 2019–2020, extreme fires burned 97 000 km2 of native vegetation in south‐eastern Australia, affecting many areas of rainforest, which has historically burned less frequently. One year post‐fires, we surveyed litter macroinvertebrates in 52 temperate rainforest sites. Sites had experienced increasing levels of fire severity (unburnt, medium severity and high severity). We asked how fire severity affected: (1) litter macroinvertebrate habitats; (2) the abundance of litter macroinvertebrate taxa per unit area; and (3) abundance relative to litter habitat (volumetric density). We also estimated the loss of litter macroinvertebrates across rainforests in the study region. High severity burns supported only a fifth of the litter volume and canopy cover as unburnt sites, lower soil moisture and higher herb cover. Medium burns were intermediate. Macroinvertebrate abundance declined with burn severity: high severity burns supported only 26% of the abundance in unburnt sites; medium severity burns supported 80% of that in unburnt sites. Patterns were similar for all taxa, with millipedes declining most. High severity fires resulted in up to 1.90 million fewer macroinvertebrates per hectare; 0.53 million fewer per hectare of medium burn rainforest. Across the study region, we estimate that 60 billion fewer litter macroinvertebrates persisted in temperate rainforests alone. Volumetric densities of many litter macroinvertebrate taxa in high severity burns were marginally higher than in unburnt sites, suggesting nutrients may be more available post‐fire, or that persisting individuals become concentrated in the leaf litter. For less desiccation‐tolerant groups (e.g., amphipods), density declines with increasing severity may reflect the combined impact of low soil moisture and reduced litter cover. Many taxa persisted following high severity fires, but declines were substantial, and taxa differed in their vulnerability. Longer‐term monitoring is required to understand the recovery trajectory and impacts on ecological function. [ABSTRACT FROM AUTHOR]

Forests worldwide support insect biodiversity and the ecosystem services provided by insects such as pollination. As forest health declines, management that emulates historical disturbance regimes has the potential to restore and maintain forest ecosystem functioning; however, we lack understanding of how these practices affect key mutualists like bees and the ecosystem services they provide.To fill this knowledge gap, we investigated the functional response of bee communities to temperate deciduous forest management practices that emulate historical disturbances (burning, thinning and the combination of the two). We also investigated whether seasonality has any effect on this relationship.Bee functional diversity was highest in spring compared to summer, and management did not affect this relationship. Instead, different management strategies aligned with specific bee functional traits and these relationships varied throughout the year. Managed and unmanaged areas differed in the distribution of nesting and floral resources and, as a result, altered bee functional trait composition. Thinned plots with increased floral resources promoted smaller bees with limited dispersal capacity, in addition to primitively eusocial and cavity‐excavating bees. Unmanaged habitat supported vulnerable bee groups such as cleptoparasites and specialists. Burning by itself or in combination within thinning may have eliminated crucial nesting resources such as deadwood that bees depend on in forests.Synthesis and applications: Our findings demonstrate that managing temperate forests by emulating historical disturbances can support a functionally diverse bee community and highlight the need to consider temporal variation in the environmental drivers of forest bee communities. To support year‐round bee diversity, forest management strategies should prioritize floral resources and leave behind deadwood to increase bee nesting resources, as well as maintain unmanaged habitat within the forest landscape. Overall, our study reinforces the importance of using a range of forest management strategies to enhance bee functional diversity and associated ecosystem services. [ABSTRACT FROM AUTHOR]

This paper focuses on the current state of mangroves in Egypt, analyses how climate change is affecting mangrove forests and suggests a conservation strategy to safeguard this valuable maritime resource. Mangroves in Egypt are primarily found in regions around the Red Sea, making them popular for ecotourism across the globe. A crucial breeding and feeding ground for many commercial fishery species, mangroves are a maritime habitat that is both economically and environmentally significant and a variety of living things call them home. Mangroves are one of the most threatened tropical and subtropical ecoregions in the world. These threats come from both natural and human sources, including oil spills, human waste runoff, herbicide use, and coastal development, all of which have the potential to harm the environment. Mangrove habitats are immediately impacted by salinity changes and rising sea levels brought on by climate change. This is unfortunate as mangroves are one of the most important global carbon sinks, and their loss due to climate change may accelerate sea level rise and ocean acidification, which will cause the extinction of numerous commercial fish species. A conservation strategy should be implemented to safeguard the mangroves around the Egyptian Red Sea by using mitigation techniques, creating marine protected zones near the mangroves, and consulting the owners of the mangrove stalks. Analysis of multi-temporal satellite imagery is one of the most significant methods to assist decision-makers and environmental planners in obtaining high-precision information about environmental and climatic changes. Analysis of satellite imagery is a valuable way to detect, monitor, assess and map the environmental, human, and natural activities that are threatening the growth of the mangrove forest ecosystem. Change detection analyses using satellite imagery were conducted to evaluate the effects of rapid coastal sustainable development, including human urban and tourism activities; the decline and destruction of large areas of the mangrove forest for animal feeding along camel trade roads; and the threat of natural impacts such as flash flooding, coastal and soil erosion or human impacts such as established desalination plants and other human activities along the coastal zone of the Egyptian Red Sea. [ABSTRACT FROM AUTHOR]

Land use/cover change (LULCC) is an integral part of global environmental change and is influenced by both natural and socioeconomic factors. This study aims to comprehensively analyze land use and land cover (LULC) in Kwazulu-Natal and Mpumalanga provinces in eastern South Africa from 1995 to 2020 and to identify the driving force behind LULCC. Utilizing Landsat series satellite imagery as a data source and based on the Google Earth Engine (GEE) platform and eCognition software 9.0, two different classification methods, pixel-based classification and object-oriented classification, were adopted to gather LULC data every five years. The spatiotemporal characteristics of the data were then analyzed. Using an optimal parameter-based geodetector (OPGD), this study explored the driving factors of LULCC in this region. The results show the following: (1) Of the two classification methods examined, the object-oriented classification had higher accuracy, with an overall accuracy of 80–90%. The pixel-based classification had lower accuracy, with an overall accuracy of 62.33–72.14%. (2) From 1995 to 2020, the area of farmland in the study area showed a fluctuating increase, while the areas of forest and grassland declined annually. The area of constructed land increased annually, whereas the areas of water and unused land fluctuated over time. (3) Socioeconomic factors generally had greater explanatory power than natural factors, with population growth and economic development being the main drivers of LULCC in the region. This study provides a reliable scientific basis for the formulation of sustainable land resource development strategies in the area, as well as for the management and implementation of urban and rural planning, ecological protection, and environmental governance by relevant departments. [ABSTRACT FROM AUTHOR]

Warming ocean temperatures have been linked to kelp forest declines worldwide, and elevated temperatures can act synergistically with other local stressors to exacerbate kelp loss. The bull kelp Nereocystis luetkeana is the primary canopy‐forming kelp species in the Salish Sea, where it is declining in areas with elevated summer water temperatures and low nutrient concentrations. To determine the interactive effects of these two stressors on microscopic stages of N. luetkeana, we cultured gametophytes and microscopic sporophytes from seven different Salish Sea populations across seven different temperatures (10–22°C) and two nitrogen concentrations. The thermal tolerance of microscopic gametophytes and sporophytes was similar across populations, and high temperatures were more stressful than low nitrogen levels. Additional nitrogen did not improve gametophyte or sporophyte survival at high temperatures. Gametophyte densities were highest between 10 and 16°C and declined sharply at 18°C, and temperatures of 20 and 22°C were lethal. The window for successful sporophyte production was narrower, peaking at 10–14°C. Across all populations, the warmest temperature at which sporophytes were produced was 16 or 18°C, but sporophyte densities were 78% lower at 16°C and 95% lower at 18°C compared to cooler temperatures. In the field, bottom temperatures revealed that the thermal limits of gametophyte growth (18°C) and sporophyte production (16–18°C) were reached during the summer at multiple sites. Prolonged exposure of bull kelp gametophytes to temperatures of 16°C and above could limit reproduction, and therefore recruitment, of adult kelp sporophytes. [ABSTRACT FROM AUTHOR]

This article explores the relationship between tree water deficit (TWD) and stem radial growth in mixed forests. The study examines the effects of neighborhood composition and functional traits on TWD and stem radial growth using data from a tree diversity manipulation experiment in subtropical China. The results suggest that functional dissimilarity among trees at the neighborhood scale can mitigate water deficit and promote stem radial growth. The findings highlight the importance of considering functional diversity and species interactions in forest management practices. [Extracted from the article]

Compound drought‐heatwave (CDHW) events threaten ecosystem productivity and are often characterized by low soil moisture (SM) and high vapor pressure deficit (VPD). However, the relative roles of SM and VPD in constraining forest productivity during CDHWs remain controversial. In the summer of 2022, China experienced a record‐breaking CDHW event (DH2022). Here, we applied satellite remote‐sensing data and meteorological data, and machine‐learning techniques to quantify the individual contributions of SM and VPD to forest productivity variations and investigate their interactions during the development of DH2022. The results reveal that SM, rather than VPD, dominates the forest productivity decline during DH2022. We identified a possible critical tipping point of SM below which forest productivity would quickly decline with the decreasing SM. Furthermore, we illuminated the evolution of SM, VPD, evapotranspiration, forest productivity, and their interactions throughout DH2022. Our findings broaden the understanding of forest response to extreme CDHWs at the ecosystem scale. Plain Language Summary: Low soil moisture (SM) and high vapor pressure deficit (VPD) are widely recognized as the dominant drivers of forest productivity decline during compound drought‐heatwave (CDHW) events. In the summer of 2022, a record‐breaking CDHW (DH2022) struck China. In this study, we decoupled the respective impacts of SM and VPD in determining forest productivity decline during DH2022. We found that during DH2022, SM, rather than VPD, is the dominant driver of forest productivity decline, and once SM decreases below a certain threshold, forest productivity would decline sharply. We illuminated the evolution of SM, VPD, evapotranspiration, forest productivity, and their interactions throughout DH2022. Our findings promote the understanding of forest response to extreme CDHWs at the ecosystem scale and thus potentially improve terrestrial ecosystem models' ability to evaluate and predict the impacts of CDHWs. Key Points: Soil moisture (SM), rather than vapor pressure deficit, dominates the forest productivity decline in the 2022 China compound drought‐heatwave eventForest productivity would decline sharply once SM drops below a certain threshold during extreme compound drought‐heatwave eventsEvolution of the 2022 China compound drought‐heatwave event and its impacts on forests were illuminated [ABSTRACT FROM AUTHOR]

While some agricultural landscapes can support wildlife in the short term, it is uncertain how well they can truly sustain wildlife populations. To compare population trends in different production systems, we sampled birds along 48 transects in mature forests, diversified farms, and intensive farms across Costa Rica from 2000 to 2017. To assess how land use influenced population trends in the 349 resident and 80 migratory species with sufficient data, we developed population models. We found, first, that 23% of species were stable in all three land use types, with the rest almost evenly split between increasing and decreasing populations. Second, in forest habitats, a slightly higher fraction was declining: 62% of the 164 species undergoing long-term population changes; nearly half of these declines occurred in forest-affiliated invertivores. Third, in diversified farms, 49% of the 230 species with population changes were declining, with 60% of these declines occurring in agriculture-affiliated species. In contrast, 51% of the species with population changes on diversified farms showed increases, primarily in forest-affiliated invertivores and frugivores. In intensive farms, 153 species showed population changes, also with similar proportions of species increasing (50%) and decreasing (50%). Declines were concentrated in agriculture-affiliated invertivores and forest-affiliated frugivores; increases occurred in many large, omnivorous species. Our findings paint a complex picture but clearly indicate that diversified farming helps sustain populations of diverse, forest-affiliated species. Despite not fully offsetting losses in forest habitats, diversified farming practices help sustain wildlife in a critical time, before possible transformation to nature-positive policies and practices. [ABSTRACT FROM AUTHOR]

The proliferation in mesoherbivore numbers and their associated impact on the detrital ground cover were deemed responsible for the decline in fossorial herpetofaunal densities in Ndumo Game Reserve during the early 2000s. Subsequent increased poaching pressure and wildlife declines allowed the reassessment of the sand forest fossorial herpetofaunal community to test this assumption. We found no significant increase in the two most abundant soil‐living reptiles despite significant mesoherbivore declines. This may indicate that either fossorial herpetofaunal numbers increase very slowly, or that the initial two survey methodologies were incomparable. Alternatively, some unknown environmental factor may be suppressing populations or the survey results are not representative of the fossorial herpetofaunal community. [ABSTRACT FROM AUTHOR]

Tropical montane cloud forests (TMCFs) are expected to experience more frequent and prolonged droughts over the coming century, yet understanding of TCMF tree responses to moisture stress remains weak compared with the lowland tropics. We simulated a severe drought in a throughfall reduction experiment (TFR) for 2 years in a Peruvian TCMF and evaluated the physiological responses of several dominant species (Clusia flaviflora Engl. Weinmannia bangii (Rusby) Engl. Weinmannia crassifolia Ruiz & Pav. and Prunus integrifolia (C. Presl) Walp). Measurements were taken of (i) sap flow; (ii) diurnal cycles of stem shrinkage, stem moisture variation and water-use; and (iii) intrinsic water-use efficiency (iWUE) estimated from foliar δ13C. In W. bangii , we used dendrometers and volumetric water content (VWC) sensors to quantify daily cycles of stem water storage. In 2 years of sap flow (Js) data, we found a threshold response of water use to vapor pressure deficit vapor pressure deficit (VPD) > 1.07 kPa independent of treatment, though control trees used more soil water than the treatment trees. The daily decline in water use in the TFR trees was associated with a strong reduction in both morning and afternoon Js rates at a given VPD. Soil moisture also affected the hysteresis strength between Js and VPD. Reduced hysteresis under moisture stress implies that TMCFs are strongly dependent on shallow soil water. Additionally, we suggest that hysteresis can serve as a sensitive indicator of environmental constraints on plant function. Finally, 6 months into the experiment, the TFR treatment significantly increased iWUE in all study species. Our results highlight the conservative behavior of TMCF tree water use under severe soil drought and elucidate physiological thresholds related to VPD and its interaction with soil moisture. The observed strongly isohydric response likely incurs a cost to the carbon balance of the tree and reduces overall ecosystem carbon uptake. [ABSTRACT FROM AUTHOR]

Two coastal areas located on the North-Western side of Corsica Island have been investigated to reconstruct their Mid- to Late-Holocene landscape evolution together with the history of human occupation. Particular attention has been paid to the study of shoreline migration and vegetation history alongside land-use. Three boreholes were drilled to a maximum depth of 4.20 m and laboratory work comprised the identification of molluscs and pollen/NPPs as well as sedimentological analyses. Chronostratigraphy is based on a series of 18 radiocarbon datings and enabled to reconstruct the environments in the Fangu Estuary to the north of the World Heritage site over the last six millennia, and over the last four millennia on the Girolata coastal plain to the south. Palaeogeographic reconstruction of shoreline mobility is established for each site based on borehole chronostratigraphy analysis. In addition, two original pollen and NPPs diagrams have been established for the Girolata and Fangu sites. These reveal that anthropogenic activities began to significantly impact local vegetation cover ca. 2500 years BP at Girolata, and ca. 2000 years BP at Fangu. Of particular interest, our work records the first complete pollen sequence in Corsica for Roman times at Girolata: first, the exploitation of cereals, grapevines and the development of husbandry is observed during the Roman Republic (500 BCE–0), followed by the almost exclusive cultivation of Olea sp. during the Roman Empire (0–500 CE). Following this, and using other regional pollen studies obtained for NW Corsica, we propose a regional evolution of the complex human-environment interactions for the last six millennia. Our results reveal a peak of regional forest decline (the most intense event recorded for the Late-Holocene) from the 11th to the 16th centuries CE which can be attributed to the exploitation of wood resources during the Pisan and Genoese dominations of the island. [ABSTRACT FROM AUTHOR]

Pollen analysis of a marine core collected in the Gulf of S. Eufemia (Tyrrhenian Calabria, Italy) allowed reconstructing the regional changes in vegetation and land use over the last 5000 years. Pollen diagram zonation through Constrained Cluster Analysis highlighted three compositional zones whose boundaries mark the major changes that affected the vegetation structure. A dense forest cover with a few signs of human activities characterized the wide pollen source area from 5055 to 2700 BP (Zone 1). In this period, the Pre-Protohistoric communities were mainly concentrated on the Tropea Promontory where they had a significant local impact. Minor forest rarefactions at 5000–4800 BP, ca. 4400–4000 BP, ca. 3450–3150 BP were correlated to phases of climatic shifts toward aridity. From 2700 to 2000 BP (Zone 2a), a longer and more incisive period of forest decline was connected to a time of aridity that favored the intense activities of an increasing anthropogenic pressure. Indeed, important urban centers developed in the area during the Greek and Roman colonization. Diffuse deforestation and cultivation occurred from 790 BP (Zone 3), enhancing soil erosion and fluvial discharge as testified by the sudden increase in sedimentation rates. This disruption of the slope morphodynamics was connected to the collapse of territorial management following the end of the Western Roman Empire. Compositional Data Analysis, applied to a simplified pollen dataset, highlighted both a negative correlation between Abies and Fagus and a close similarity between the AP/NAP curve and the Axis 1 scores of the Relative Variation Biplot. [ABSTRACT FROM AUTHOR]