Extensive Mortality Research Articles

Ips typographus vision system: a comprehensive study.

Aggressive bark beetle species such as the Eurasian spruce bark beetle Ips typographus play a fundamental role in forest ecosystems but can also lead to extensive forest mortality and massive economic damage during outbreaks. Currently I. typographus' eyes, visual perception of the world and recognition of specific targets like host plants are understudied topics. Studying its visual sense can open the way to novel efficient monitoring and management methods, particularly important in avoiding the switch from an endemic to an epidemic condition. In addition, the integration of visual cues in trapping systems may offer new opportunities for surveillance. Vision in I. typographus was investigated by means of morphological analysis, electroretinography (ERG), molecular analysis of opsin genes and behavioural tests. ERG has revealed that the compound eyes contain two classes of photoreceptors, maximally sensitive to UV and green at 370 and 530nm, respectively. The result was further supported by the identification of two relevant opsin genes. Finally, the innate wavelength sensitivity was tested in a Y-maze. Ips typographus consistently preferred UV over non-UV (VIS) light, irrespective of their intensity ratios, but preferred high over low intensity VIS light, consistent with a UV-VIS dichromatic visual system. Overall, the results may open the way to better understand the navigation pattern in tree canopies and the host selection processes of this ecologically and economically important beetle species.

Tree Mortality, Biome Shifts, and Living Sustainably to Halt Human-Caused Climate Change

Human-caused climate change has caused extensive tree mortality across West Africa and the western United States and biome shifts around the world. Reducing excessive material consumption by people offers a solution to halt climate change and risks to trees.

Overexpression of Ginkbilobin-2 homologous domain gene improves tolerance to Phytophthora cinnamomi in somatic embryos of Quercus suber

In recent decades an extensive mortality and decline of Quercus suber populations mainly caused by Phytophthora cinnamomi has been observed. In the current study, a chestnut gene homologous to ginkbilobin-2 (Cast_Gnk2-like), which in Ginkgo biloba codifies an antifungal protein, was transferred into cork oak somatic embryos of three different embryogenic lines by Agrobacterium mediated transformation. The transformation efficiency varied on the genotype from 2.5 to 9.2%, and a total of 22 independent transformed lines were obtained. The presence of Cast_Gnk2-like gene in transgenic embryos was verified in all lines by PCR. The number of transgene copies was estimated by qPCR in embryogenic lines with high proliferation ability and it varied between 1 and 5. In addition, the expression levels of Cast_Gnk2-like gene were determined in the embryogenic lines, with higher levels in lines derived from the genotype ALM6-WT. Transgenic plants were obtained from all transgenic lines and evaluated after cold storage of the somatic embryos for 2 months and subsequent transfer to germination medium. In vitro tolerance tests made under controlled conditions and following zoospore treatment showed that plants overexpressing Cast_Gnk2-like gene improved tolerance against Pc when compared to wild type ones.

Short-term exposure to ambient fine particulate matter constituents and myocardial infarction mortality

Short-term ambient fine particulate matter (PM2.5) exposure has been related to an increased risk of myocardial infarction (MI) death, but which PM2.5 constituents are associated with MI death and to what extent remain unclear. We aimed to explore the associations of short-term exposure to PM2.5 constituents with MI death and evaluate excess mortality. We conducted a time-stratified case-crossover study on 237,492 MI decedents in Jiangsu province, China during 2015–2021. Utilizing a validated PM2.5 constituents grid dataset at 1 km spatial resolution, we estimated black carbon (BC), organic carbon (OC), sulfate (SO42−), nitrate (NO3−), ammonium (NH4+), and chloride (Cl−) exposure by extracting daily concentrations grounding on the home address of each subject. We employed conditional logistic regression models to evaluate the exposure-response relationship between PM2.5 constituents and MI death. Overall, per interquartile range (IQR) increase of BC (lag 06-day; IQR: 1.75 μg/m3) and SO42− (lag 04-day; IQR: 5.06 μg/m3) exposures were significantly associated with a 3.91% and 2.94% increase in odds of MI death, respectively, and no significant departure from linearity was identified in the exposure-response curves for BC and SO42−. If BC and SO42− exposures were reduced to theoretical minimal risk exposure concentration (0.89 μg/m3 and 1.51 μg/m3), an estimate of 4.55% and 4.80% MI deaths would be avoided, respectively. We did not find robust associations of OC, NO3−, NH4+, and Cl− exposures with MI death. Individuals aged ≥80 years were more vulnerable to PM2.5 constituent exposures in MI death (p for difference <0.05). In conclusion, short-term exposure to PM2.5-bound BC and SO42− was significantly associated with increased odds of MI death and resulted in extensive excess mortality, notably in older adults. Our findings emphasized the necessity of reducing toxic PM2.5 constituent exposures to prevent deaths from MI and warranted further studies on the relative contribution of specific constituents.

Computational Analysis of the Accumulation of Mutations in Therapeutically Important RNA Viral Proteins During Pandemics with Special Emphasis on SARS-CoV-2

Single stranded RNA viruses are primary causative agents for pandemics, causing extensive morbidity and mortality worldwide. A pivotal question in pandemic preparedness and therapeutic intervention is what are the specific mutations which are more likely to emerge during such global health crises? This study aims to identify markers for mutations with the highest probability of emergence in these pandemics, focusing on the SARS-CoV-2 spike protein, an essential and therapeutically significant viral protein, starting from sequence information from the onset of the pandemic until July 2022. Quite consistently, we observed that emerged mutations tended to demonstrate a high genetic score, which reflects high similarity of the type of codon required for translation between an amino acid and to the mutated one. Further, this pattern is also observed in therapeutically significant proteins of other ssRNA pandemic viruses, including influenza (HA, NA), spike proteins of Ebola, envelope of Dengue and Chikungunya. We propose that the genetic score serves as an initial indicator, preceding the actual impact of the mutation on viral fitness. Finally, we developed a comprehensive computational pipeline to further explore and predict the subsequent effects of mutations on viral fitness. We believe that our pipeline can narrow down and predict future mutations in therapeutically important viral proteins during a pandemic.

A confirmation of the predictive utility of the Antibiotic Use Questionnaire

BackgroundThe change in the efficacy of antimicrobial agents due to their misuse is implicated in extensive health and mortality related concerns. The Antibiotics Use Questionnaire (AUQ) is a theory driven measure based on the Theory of Planned Behaviour (TpB) factors that is designed to investigate drivers of antibiotic use behaviour. The objective of this study is to replicate the factor structure from the pilot study within a similar Australian confirmation cohort, and to extend this through investigating if the factor structure holds in a Chinese-identifying cohort.MethodsThe AUQ was disseminated to two cohorts: a confirmation cohort similar to the original study, and a Chinese identifying cohort. Data analysis was completed on the two data sets independently, and on a combined data set. An orthogonal principal components analysis with varimax rotation was used to assess the factor structure, followed by general linear models to determine the influence of the TpB factors on reported antibiotic use.Results370 participant responses from the confirmation cohort, and 384 responses from the Chinese-identifying cohort were retained for analysis following review of the data. Results showed modest but acceptable levels of internal reliability across both cohorts. Social norms, and the interaction between attitudes and beliefs and knowledge were significant predictors of self-reported antibiotic use in both cohorts. In the confirmation cohort healthcare training was a significant predictor, and in the Chinese-identifying cohort education was a significant predictor. All other predictors tested produced a nonsignificant relationship with the outcome variable of self-reported antibiotic use.ConclusionsThis study successfully replicated the factor structure of the AUQ in a confirmation cohort, as well as a cohort that identified as culturally or legally Chinese, determining that the factor structure is retained when investigated across cultures. The research additionally highlights the need for a measure such as the AUQ, which can identify how differing social, cultural, and community factors can influence what predicts indiscriminate antibiotic use. Future research will be required to determine the full extent to which this tool can be used to guide bespoke community level interventions to assist in the management of antimicrobial resistance.

Bioactivity of synthetic peptides from Ecuadorian frog skin secretions against Leishmania mexicana, Plasmodium falciparum, and Trypanosoma cruzi.

Chagas disease, leishmaniasis, and malaria are major parasitic diseases disproportionately affecting the underprivileged population in developing nations. Finding new, alternative anti-parasitic compounds to treat these diseases is crucial because of the limited number of options currently available, the side effects they cause, the need for long treatment courses, and the emergence of drug-resistant parasites. Anti-microbial peptides (AMPs) derived from amphibian skin secretions are small bioactive molecules capable of lysing the cell membrane of pathogens while having low toxicity against human cells. Here, we report the anti-parasitic activity of five AMPs derived from skin secretions of three Ecuadorian frogs: cruzioseptin-1, cruzioseptin-4 (CZS-4), and cruzioseptin-16 from Cruziohyla calcarifer; dermaseptin-SP2 from Agalychnis spurrelli; and pictuseptin-1 from Boana picturata. These five AMPs were chemically synthesized. Initially, the hemolytic activity of CZS-4 and its minimal inhibitory concentration against Escherichia coli, Staphylococcus aureus, and Candida albicans were determined. Subsequently, the cytotoxicity of the synthetic AMPs against mammalian cells and their anti-parasitic activity against Leishmania mexicana promastigotes, erythrocytic stages of Plasmodium falciparum and mammalian stages of Trypanosoma cruzi were evaluated in vitro. The five AMPs displayed activity against the pathogens studied, with different levels of cytotoxicity against mammalian cells. In silico molecular docking analysis suggests this bioactivity may occur via pore formation in the plasma membrane, resulting in microbial lysis. CZS-4 displayed anti-bacterial, anti-fungal, and anti-parasitic activities with low cytotoxicity against mammalian cells. Further studies about this promising AMP are required to gain a better understanding of its activity.IMPORTANCEChagas disease, malaria, and leishmaniasis are major tropical diseases that cause extensive morbidity and mortality, for which available treatment options are unsatisfactory because of limited efficacy and side effects. Frog skin secretions contain molecules with anti-microbial properties known as anti-microbial peptides. We synthesized five peptides derived from the skin secretions of different species of tropical frogs and tested them against cultures of the causative agents of these three diseases, parasites known as Trypanosoma cruzi, Plasmodium falciparum, and Leishmania mexicana. All the different synthetic peptides studied showed activity against one of more of the parasites. Peptide cruzioseptin-4 is of special interest since it displayed intense activity against parasites while being innocuous against cultured mammalian cells, which indicates it does not simply hold general toxic properties; rather, its activity is specific against the parasites.

Coordinated action of a gut-liver pathway drives alcohol detoxification and consumption.

Alcohol use disorder (AUD) affects millions of people worldwide, causing extensive morbidity and mortality with limited pharmacological treatments. The liver is considered as the principal site for the detoxification of ethanol metabolite, acetaldehyde (AcH), by aldehyde dehydrogenase 2 (ALDH2) and as a target for AUD treatment, however, our recent data indicate that the liver only plays a partial role in clearing systemic AcH. Here we show that a liver-gut axis, rather than liver alone, synergistically drives systemic AcH clearance and voluntary alcohol drinking. Mechanistically, we find that after ethanol intake, a substantial proportion of AcH generated in the liver is excreted via the bile into the gastrointestinal tract where AcH is further metabolized by gut ALDH2. Modulating bile flow significantly affects serum AcH level and drinking behaviour. Thus, combined targeting of liver and gut ALDH2, and manipulation of bile flow and secretion are potential therapeutic strategies to treat AUD.

Endovascular thrombectomy provides durable, symptomatic relief in iliocaval tumor thrombosis

Iliocaval venous tumor thrombus is a morbid condition associated with chronic venous stasis, lower extremity edema/pain, extensive thrombus burden and high mortality secondary to critical flow obstruction, intracardiac thrombus extension and tumor embolization. Typically resistant to medical therapy, management is primarily surgical, presenting challenges for medically complex patients with widespread or end-stage disease. Mechanical or aspiration thrombectomy represents an appealing treatment strategy but data are lacking. We performed a single-center, 10-year, retrospective review of patients with pathology-confirmed, iliocaval tumor thrombus who underwent thrombectomy. 14 patients met inclusion criteria and were managed by 18 procedures over this period. The most common malignancy was renal-cell carcinoma (n=7; 50%); other types included germ cell (n=2; 14%), other genitourinary (n=2; 14%), neuroendocrine (n=1; 7%), soft tissue (n=1; 7%), and skin cell malignancies (n=1; 7%). All patients had thrombus involving the distal inferior venous cava (IVC), 50% had bilateral iliac involvement and 29% atrial involvement. Common indications were venous obstruction symptoms (n=11; 65%) and evidence of embolism (n=6; 35%). All patients tolerated the procedures without acute complication. The technical success rate was 94%, with marked improvement of flow and reduction in thrombus burden, and 79% had subjective symptomatic improvement. All patients survived for >2 weeks and 50% had long-term survival of >1 year, with 86% of these patients having renal-cell carcinoma (RCC). Three patients underwent multiple thrombectomies within days to weeks, with ultimate symptomatic improvement. Overall, our study results suggest mechanical or aspiration thrombectomy as a safe and efficacious treatment for patients with iliocaval tumor thrombus.

Photosynthetic response to a winter heatwave in leading and trailing edge populations of the intertidal red alga Corallina officinalis (Rhodophyta)

Marine heatwaves (MHWs) caused by anthropogenic climate change are becoming a key driver of change at the ecosystem level. Thermal conditions experienced by marine organisms across their distribution, particularly towards the equator, are likely to approach their physiological limits, resulting in extensive mortality and subsequent changes at the population level. Populations at the margins of their species’ distribution are thought to be more sensitive to climate-induced environmental pressures than central populations, but our understanding of variability in fitness-related physiological traits in trailing versus leading-edge populations is limited. In a laboratory simulation study, we tested whether two leading (Iceland) and two trailing (Spain) peripheral populations of the intertidal macroalga Corallina officinalis display different levels of maximum potential quantum efficiency (Fv/Fm) resilience to current and future winter MHWs scenarios. Our study revealed that ongoing and future local winter MHWs will not negatively affect leading-edge populations of C. officinalis, which exhibited stable photosynthetic efficiency throughout the study. Trailing edge populations showed a positive though non-significant trend in photosynthetic efficiency throughout winter MHWs exposure. Poleward and equatorward populations did not produce significantly different results, with winter MHWs having no negative affect on Fv/Fm of either population. Additionally, we found no long-term regional or population-level influence of a winter MHWs on this species’ photosynthetic efficiency. Thus, we found no statistically significant difference in thermal stress responses between leading and trailing populations. Nonetheless, C. officinalis showed a trend towards higher stress responses in southern than northern populations. Because responses rest on a variety of local population traits, they are difficult to predict based solely on thermal pressures.

Nasal cathelicidin is expressed in early life and is increased during mild, but not severe respiratory syncytial virus infection

Respiratory syncytial virus is the major cause of acute lower respiratory tract infections in young children, causing extensive mortality and morbidity globally, with limited therapeutic or preventative options. Cathelicidins are innate immune antimicrobial host defence peptides and have antiviral activity against RSV. However, upper respiratory tract cathelicidin expression and the relationship with host and environment factors in early life, are unknown. Infant cohorts were analysed to characterise early life nasal cathelicidin levels, revealing low expression levels in the first week of life, with increased levels at 9 months which are comparable to 2-year-olds and healthy adults. No impact of prematurity on nasal cathelicidin expression was observed, nor were there effects of sex or birth mode, however, nasal cathelicidin expression was lower in the first week-of-life in winter births. Nasal cathelicidin levels were positively associated with specific inflammatory markers and demonstrated to be associated with microbial community composition. Importantly, levels of nasal cathelicidin expression were elevated in infants with mild RSV infection, but, in contrast, were not upregulated in infants hospitalised with severe RSV infection. These data suggest important relationships between nasal cathelicidin, upper airway microbiota, inflammation, and immunity against RSV infection, with interventional potential.

Fabrication of CNT-supported dendritic silver nanocomposites for efficient electrochemical detection of breast cancer biomarker

Breast cancer is a fatal disease arising worldwide with an extensive high mortality rate. Monitoring and early detection of the biomarkers of the cancer can be a medium to restrain it from being lethal. The present study investigates the synthesis of carbon nanotubes (CNTs) supported copper dealloyed silver nanocomposite modified novel biosensor for superior electrocatalytic performance towards histidine (His); a biomarker of breast cancer (BC). The fabrication method employs electrochemical deposition of copper-silver (Cu-Ag) alloy on the CNT-modified probe (CuAg/CNT//GCE alloy) and subsequent dealloying of the elemental Cu leading to the development of dealloyed Ag/CNT//GCE sensor. The impact of the fabrication procedure enabled the proposed sensor to exhibit ∼ 1.7 and ∼ 2.27 folds higher electrocatalytic response than CuAg/CNT//GCE alloy and other modified electrodes, respectively. The amperometric response of the dealloyed Ag/CNT//GCE displays two moderate dynamic ranges within (i) 0.5 – 20 μM with a detection limit (LoD) of 0.48 μM (S/N = 3), and (ii) 20 – 500 μM with a LoD of 1.04 μM for His. A high anti-interference ability of the modified probe is also noticed towards different amino acids. Finally, the proposed sensor has been tested for determination of His in real samples, with satisfactory recovery results. The precision and comprehensive performance justify the sensor to be a potential candidate for monitoring clinical projects.

Field phenology of emerald ash borer (Coleoptera: Buprestidae) parasitoids in New York State.

Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), has caused extensive mortality of ash across North America. Biological control offers a potential long-term management option, allowing for long-term survival of ash. Careful monitoring of populations of biocontrol agents is necessary to understand their relative impacts. Understanding the emergence and flight phenology of these species allows for the optimization of monitoring schemes and improves our understanding of host-parasitoid interactions. We used yellow pan trapping data to assess the adult phenology of both EAB and its associated native and introduced parasitoids in 3 New York counties. We monitored 2 introduced larval biocontrol agents, Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) and Spathius galinae Belokobylskij & Strazanac (Braconidae), for 3-4 years post-release, as well as the native parasitoid Phasgonophora sulcata Westword (Chalcididae). Results indicate a single discrete emergence event for both EAB and P. sulcata in all monitored counties, which is consistent with previously reported results. Our results also suggest there are 4 generations per year of T. planipennisi and 3 generations of S. galinae in the monitored counties. We recorded an additional generation of T. planipennisi that had not previously been reported in New York, and both T. planipennisi and S. galinae appeared to emerge earlier than previously documented.

Redbay (Persea borbonia L. Spreng) Seedling and Sapling Growth and Recruitment Near Trees with and without Putative Resistance to Laurel Wilt Disease

Laurel wilt, a fungal disease (Harringtonia lauricola T.C. Harr., Fraedrich and Aghayeva) spread by the Asian redbay ambrosia beetle [Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae)], presents an imminent threat to North American members of the Lauraceae family, having caused extensive mortality in several species, especially redbay (Persea borbonia L. Spreng). Varying levels of disease resistance have been recorded in redbay under controlled conditions. To investigate if previously monitored putatively resistant field redbays have influenced the regeneration and survival of conspecifics within the surrounding 0.08 ha, a survey was conducted in 2018-19 and compared to similar data collected years prior (2008-09, 2013) along the coasts of Florida, Georgia, and South Carolina, United States. Plots were originally established at six disease-infested study sites around large redbay (&gt;7.5-cm diameter at breast height (1.37 m) (DBH)) that had survived the initial laurel wilt disease epidemic that began in approximately 2007. In 2018-19, a subset of 61 plots within 16 m of the original “survivor” redbay were recorded and compared to previous surveys. Among the original redbay selected for resistance, 22 of 61 (36%) survivors across all sites were alive in 2018 with survival rates varying from 0 to 70% between survey periods (average mortality 3.6%/year). Trees that died in years since 2008-09 had their plots reclassified as susceptible or “suscepts”. Changes in mean quadratic diameter at 1.37 m of redbay plots near survivors were significantly greater than those near suscepts, and in 2018-19, the average diameter of redbay near survivors was 7.62 cm vs. 4.90 cm for suscepts. The diameter distribution of dead and live redbay in the whole population showed a decrease in live individuals surviving past 8 cm DBH in 2018–2019, but 20 of 22 survivor candidate trees were larger than 8 cm DBH. Regeneration was occurring both clonally and sexually and tended to be greater near suscepts, but midstory resprouts per hectare and understory seedlings interacted significantly with the site and the latter differed between sites. These findings indicate that redbay is regenerating in these ecosystems, and disease resistance may allow for increased average tree size for some individuals, but an upper size threshold of around 8 cm DBH may still exist for much of the population. In addition, the importance of site variables in regeneration was apparent, making either local genetic or environmental effects an important topic for future research. Continuing to monitor these survivors while locating new candidates for disease screenings and breeding, preventing the introductions of new strains of H. lauricola, shedding light on the nature of resistance and its heritability, and initiating outplanting trials with resistant germplasm are instrumental steps in bringing redbay back to prominence in its historical range.

Sustainability and drivers of Populus tremuloides regeneration and recruitment near the southwestern edge of its range

Abstract Quaking aspen (Populus tremuloides Michx.) ecosystems are highly valued in the southwestern United States because of the ecological, economic, and aesthetic benefits they provide. Aspen has experienced extensive mortality in recent decades, and there is evidence that many areas in Arizona, United States lack adequate recruitment to replace dying overstory trees. Maintaining sustainable levels of regeneration and recruitment (i.e. juveniles) is critical for promoting aspen ecosystem resilience and adaptive capacity, but questions remain about which factors currently limit juvenile aspen and which strategies are appropriate for managing aspen in an increasingly uncertain future. To fill these critical knowledge gaps, we sampled aspen populations across Arizona and collected data representing a suite of biotic and abiotic factors that potentially influence juvenile aspen. Specifically, we addressed two questions: (i) Is aspen sustainably regenerating and recruiting in Arizona? and (2) Which biotic and abiotic factors significantly influence aspen regeneration and recruitment? We found that many aspen populations in Arizona lack sustainable levels of juvenile aspen, and the status of recruitment was especially dire, with 40% of study plots lacking a single recruiting stem. Aspen regeneration was less abundant on warmer sites than cooler ones, highlighting the threat that a rapidly warming climate poses to aspen sustainability. Aspen recruitment was significantly more abundant in areas with recent fire than in areas without fire, and recruitment had a strong positive relationship with fire severity. The most important limiting factors for aspen recruitment were ungulate browse, especially by introduced Rocky Mountain elk (Cervus canadensis nelsoni), and the invasive insect, oystershell scale (Lepidosaphes ulmi). We conclude with a discussion of how management can promote sustainability of aspen populations by addressing the array of threats that aspen faces, such as a warming climate, chronic ungulate browse, and outbreaks of oystershell scale.

Differential phase of Platypus quercivorus attacks in urban green space: A case study on 2 urban parks in Tokyo

The ambrosia beetle Platypus quercivorus (Maruyama) transmits the pathogenic fungus Raffaelea quercivora Kubono et Shin. Ito, causing Japanese oak wilt and subsequent tree dieback. In recent years, there has been a marked increase in mortality of secondary forests due to Japanese oak wilt, especially in suburban and urban parks, as P. quercivorus finds suitable host trees and environments. To prevent extensive mortality from P. quercivorus attacks, it is crucial to establish effective management strategies for secondary forests. In this study, we aimed to investigate the occurrence patterns of P. quercivorus attacks and identify effective management strategies in urban parks that have experienced recent outbreaks of Japanese oak wilt to find any hints for establishing effective management strategies. Over a two-year period, we surveyed the occurrence of P. quercivorus attacks on Quercus serrata Murray trees along walking trails and assessed surrounding conditions. Through data analysis, we identified significant factors influencing attacks. The results revealed distinct differences in host tree condition and attack severity between parks. Although the proportion of attacked trees in one park markedly increased over the two-year period, the other park remained stable, suggesting different attack phases between parks. In the former park, the occurrence of attacks was positively correlated with tree size, severity of nearby attacks, and nearby tree dieback but negatively correlated with surrounding tree density and occurrences of last year attack. Conversely, in the latter park, only occurrences of last year attack showed a significant negative correlation with attack occurrence. This discrepancy may be attributed to variations in the attack phase of P. quercivorus in each park. From a management perspective, park managers should establish flexible forest management strategies in suburban and urban parks to adapt to different attack phases.

Assessing the impact of multi-year droughts on German forests in the context of increased tree mortality

Forests play a crucial role in climate regulation and societal well-being. Despite their significance, the increasing frequency of droughts poses a severe threat to forest ecosystems, impacting carbon sequestration and forest stability. In Germany, the unprecedented 2018–2020 drought resulted in extensive tree mortality and damaged wood volume, with lasting effects observed in subsequent years. As climate models project a continuation of such droughts, understanding the impact of droughts on forests becomes imperative. However, it is unclear how forests will evolve in the future if the drought duration continues to increase.This study employs a forest model to analyze the impact of droughts across various German forest types, focusing on the duration of drought periods and their influence on forest productivity. By utilizing an individual-based forest growth model and national forest inventories, the study addresses critical knowledge gaps regarding the effects of multi-year droughts on biomass and productivity across various forest types, including monocultures and mixed forests. The simulations consider a drought-induced large increase in tree mortality caused by factors such as pest infestations and diseases across Germany.Our simulation results reveal a declining aboveground biomass and gross primary production (GPP) for all simulated drought scenarios, including the three- and six-year drought. GPP is reduced by 46 % in the 3-year drought scenario and by 58 % in the 6-year drought scenario. Notably, prolonged droughts lead to cumulative losses, with a saturation effect in drought scenarios exceeding eight years. Forest stand composition influences these impacts, with greater GPP losses in low-biomass stands. Furthermore, different forest types exhibit varying responses. Monocultures and even-sized forests (mostly planted and managed forests) are more sensitive to drought than mixed and uneven-sized forests.The results provide valuable insights into forest resilience and ecosystem responses to increasingly frequent and prolonged droughts, highlighting the importance of understanding the effects of drought on monocultures and mixed forests to inform future forest management strategies. Modelling the influence of biotic factors on forest dynamics in a process-based manner remains a challenge that requires future research.

Habitat Degradation Facilitates the Invasion of Neophytes: A Resurvey Study Based on Permanent Vegetation Plots in Oak Forests in Slovenia (Europe).

The spread of neophytes (non-native plant species) challenges the conservation status and ecological integrity of forests, especially in lowland areas. Long-term resurvey studies are needed to evaluate the temporal dynamics of neophytes in forests; however, such data are scarce. In 2023, we resampled a set of 45 permanent vegetation plots (established in 1992/93) in two forest vegetation types: oak-hornbeam forests dominated by Quercus robur and colline oak-beech forests dominated by Q. petraea. Over the last 30 years, oak forests have experienced extensive oak tree mortality, with the degree of habitat degradation being greater in Q. robur forests. In the early 1990s, only three neophytes with low abundance were recorded across all plots. In the 2023 resurvey, the total number of neophytes increased to 22 species (15 herbaceous and 7 woody species), comprising 6.9% of the total species pool in the understory layer. The increase in the plot-level number and cover of neophytes was significant in plots dominated by Q. robur but not in those with Q. petraea. The most frequent neophytes were Impatiens parviflora (present in 31% of plots), Solidago gigantea (27%), Erigeron annuus (16%) and Erechtites hieraciifolia (16%). The richness and cover of neophytes were significantly affected by the tree layer cover (negative correlation) and the degree of soil disturbance (positive correlation). All neophytes established in disturbed patches, whereas the occurrence of I. parviflora was exceptional as it was able to colonize less degraded, shaded understory environments. Habitat degradation (the mortality-induced loss of stand-forming oak trees resulting in extensive tree layer cover decrease) emerged as a key driver promoting neophyte proliferation, coupled with the impact of management-induced disturbances affecting overstory and soil conditions. The spread is expected to continue or even intensify in the future because novel light regimes and disturbances make forest habitats less resistant to neophyte proliferation.

Improving monitoring and management methods is of the utmost importance in countries at risk of invasion by the pinewood nematode

Key messageThe invasive pine wood nematode is a major threat to pine forests worldwide, causing extensive tree mortality. Although scientific knowledge and control measures are continuously improving, important gaps remain. We argue that some key questions, notably related to early detection and pest management, need to be urgently tackled in countries at risk of invasion such as France.

Adverse Environmental Perturbations May Threaten Kelp Farming Sustainability by Exacerbating Enterobacterales Diseases.

Globally kelp farming is gaining attention to mitigate land-use pressures and achieve carbon neutrality. However, the influence of environmental perturbations on kelp farming remains largely unknown. Recently, a severe disease outbreak caused extensive kelp mortality in Sanggou Bay, China, one of the world's largest high-density kelp farming areas. Here, through in situ investigations and simulation experiments, we find indications that an anomalously dramatic increase in elevated coastal seawater light penetration may have contributed to dysbiosis in the kelp Saccharina japonica's microbiome. This dysbiosis promoted the proliferation of opportunistic pathogenic Enterobacterales, mainly including the genera Colwellia and Pseudoalteromonas. Using transcriptomic analyses, we revealed that high-light conditions likely induced oxidative stress in kelp, potentially facilitating opportunistic bacterial Enterobacterales attack that activates a terrestrial plant-like pattern recognition receptor system in kelp. Furthermore, we uncover crucial genotypic determinants of Enterobacterales dominance and pathogenicity within kelp tissue, including pathogen-associated molecular patterns, potential membrane-damaging toxins, and alginate and mannitol lysis capability. Finally, through analysis of kelp-associated microbiome data sets under the influence of ocean warming and acidification, we conclude that such Enterobacterales favoring microbiome shifts are likely to become more prevalent in future environmental conditions. Our study highlights the need for understanding complex environmental influences on kelp health and associated microbiomes for the sustainable development of seaweed farming.