Search Results (322)

The problem of water pollution by various xenobiotics has gained a lot of interest due to their persistence, bioaccumulation potential, and toxic effects on ecosystems and humans. Electrochemical sensors offer a rapid, sensitive, and cost-effective method for on-site monitoring. In this research, an electrochemical sensor for xenobiotics based on a biochar–alumina composite is developed. The biochar–alumina composites were obtained by the air-limited pyrolysis of oak sawdust in the presence of alumina. Two types of alumina were mixed with oak sawdust in three ratios and subjected to thermal treatment. The resulting composites were characterized by SEM, N₂ adsorption isotherm, XRD, and electrochemical characterization. The detection of the herbicide pendimethalin and the antibiotic ciprofloxacin was investigated, and the composite with the optimal biochar/alumina ratio was selected for each of the xenobiotics studied. A linear current response was obtained for pendimethalin in the concentration range 0.7 μM to 70.0 μM with an LOD of 0.5 μM. A linear current response was obtained for ciprofloxacin in the concentration range 1.6 μM to 55.4 μM with an LOD of 0.63 μM. A comparison of the characterization results with the electroanalytical performance implied the importance of the hydrophobic/hydrophilic nature of the electrode surface for detecting the analyte under investigation. Full article

Oak forests provide critical ecosystem services, but are being increasingly exposed to climate variability, drought, and insect outbreaks that threaten their long-term resilience. This study aims to integrate structural canopy indicators with climate-derived indices to detect early-warning signals of decline in temperate oak stands. We monitored eight Forest Management Units in western Romania between 2017 and 2021, combining field-based assessments of crown morphology, vitality traits, defoliation, and epicormic shoot frequency with hydroclimatic indices such as the Forest Aridity Index. Results revealed strong spatial and temporal variability: several stands showed advanced canopy deterioration characterized by increased defoliation, dead branches, and epicormic resprouting, while others maintained stable conditions, suggesting resilience and suitability as reference sites. Insect defoliators, particularly Geometridae, contributed additional stress, but generally at subcritical levels. By synthesizing these metrics into conceptual models and a risk scorecard, we identified the causal pathways linking climatic anomalies and biotic stressors to structural decline. The findings demonstrate that combining structural and climatic indicators offers a transferable framework for forest health monitoring, providing robust early-warning tools to guide adaptive silviculture and resilience-based management. Beyond the Romanian context, this integrative approach supports sustainability goals by strengthening conservation strategies for temperate forests under global change. Full article

Acute Oak Decline (AOD) is a progressive disease affecting oaks across Europe and is increasingly recognised as a threat to the health of forests and urban trees. While the occurrence of this disease has been documented in forest ecosystems, its presence in urban landscapes is still poorly understood. In this study, the occurrence of AOD-associated bacteria (Brenneria goodwinii, Gibbsiella quercinecans, Rahnella victoriana, Lonsdalea quercina) was investigated in Quercus robur and Q. rubra growing in urban areas of Wrocław, Poland. Multiplex real-time PCR analyses confirmed the pathogens in 11 trees, with B. goodwinii being the most common species. Importantly, we provide the first confirmed detection of B. goodwinii in Q. rubra under urban conditions, possibly the first such detection in Europe. The results show the occurrence of AOD-associated pathogens in urban environments, suggesting that such habitats may provide favourable conditions for their occurrence. However, further investigations, including epidemiological and spatial analyses, are needed to clarify whether urban areas contribute to the persistence or spread of these pathogens. Beyond local documentation, our results emphasise the need to include urban ecosystems in AOD surveillance and highlight potential pathways for pathogen adaptation and spread in cities. This work provides new insights into the ecology of AOD in anthropogenically modified habitats and has direct implications for urban tree health monitoring, biodiversity conservation, and the development of integrated management strategies. Full article

Forest ecosystems undergo seasonal shifts in bacterial and fungal communities, but little is known about the specific microbiota associated with Quercus robur–Boletus edulis systems. This study represents the first examination of seasonal changes in soil microbiota in pedunculate oak habitats in Galicia (NW Spain) and their relationship with Boletus edulis and Boletus reticulatus mycelium prevalence and concentration. Soil microbiota richness, diversity, and composition, as well as seasonal variation in Boletus mycelium, were assessed using DNA metabarcoding and qPCR, respectively. Sampling was conducted in autumn at two 30–40-year-old Q. robur stands. Bacterial communities were dominated by Acidobacteria (34%) and Proteobacteria (33%), with Acidobacterium (12%), Paludibaculum (9%), and Edaphobacter (7%) identified as most abundant. Fungal communities were primarily Basidiomycota (93%), led by Russula (46%). For both bacteria and fungi, the highest OTU richness was observed in September, followed by a significant decrease in October and a partial recovery in November. Boletus species were found to exhibit positive correlations with specific bacteria (e.g., Massilia, Rhizobium) and fungi (e.g., Amanita, Clavaria, Inocybe, Scleroderma, Suillus and Mortierella), suggesting a potential influence of these microbes on mycelium development. This study provides novel insights into the seasonal dynamics of soil microbiota and their potential role in Boletus ecology, thereby advancing understanding of host–microbe interactions in temperate forests. Full article

The biogenic organization of widespread valley pine ecosystems on sandy alluvium leads to an increase in soil fertility, productivity, and biodiversity through autogenic successions. Using our own stationary observations and literary data on the productivity of pine forests in Russia, Belarus, and Ukraine, we quantified the mechanism of autogenic forest successions associated with carbon sequestration and the influence of organic matter dynamics on the fertility and water retention of sandy soils. The low rate of organic matter turnover in primary succession leads to the intensive accumulation of thick (6–8 cm) forest litter and the formation of small humus-eluvial horizons with total carbon storage up to 50 Mg/ha. This soil structure retains 2–6 times more water and biophilic elements than in the original sandy alluvium. It is suitable for the settlement of more demanding broadleaf species and nemoral herbs with higher rates of litterfall, its decomposition and humification. As a result, simple pine forests on Arenosols and primitive Sod-podzolic soils are replaced by complex, more productive linden–oak–pine ecosystems on developed Cambisols with thick (up to 30 cm) humus horizons, carbon storage of 80–100 Mg/ha and higher (2–7 times compared to the previous soils) fertility and water-holding capacity. This mechanism is adequately described by a nonlinear process model with a trigger reaction of plant productivity to the storage and quality of soil organic matter, suitable for predicting long-term carbon sequestration during the succession of valley pine forests and the effectiveness of artificial afforestation. Full article

Atlas cedar (Cedrus atlantica (Endl.) Manetti ex Carrière) is an endemic and relict conifer species from northwestern Africa, relatively drought-tolerant but also highly sensitive to recurrent summer heat stress. Cedar forests have undergone a dramatic range contraction in recent decades. The development of effective conservation strategies requires long-term perspectives to understand how forests have responded to past disturbances. We present a multi-proxy, high-resolution analysis of a 122 cm-deep fossil record (Merj Lkhil; LKH) located at 1213 m a.s.l. in Jbel Bou Hachem (Moroccan Rif), providing insights into the fragmentation of cedar stands. Cedrus likely formed extensive lowland populations during the final stages of the Late Glacial and began migrating upslope during the Greenlandian. It reached its maximum extent in the Rif around 7000 cal yr BP. Thereafter, increasing aridity, enhanced seasonality, and growing anthropogenic pressure triggered its long-term decline. This trajectory involved a vertical reorganization of montane ecosystems, with Cedrus progressively retreating within mid- and low-elevation forests, while deciduous oaks maintained a long-term co-dominance and Q. ilex L. gradually expanded, especially at lower elevations. Today, Cedrus is confined to isolated high-elevation stands in Jbel Bou Hachem. These relic populations should be prioritized for conservation under ongoing climate and land-use change. Full article

In the context of climate change and the increasing ecological importance of pedunculate oak (Quercus robur L.) in European forests, sustainable regeneration strategies are essential for ensuring long-term forest resilience. This study investigates how different conditions of regeneration sites, namely areas under pine canopies, gaps (openings within the pine stand), inter-gap area (open zone surrounding the pine gaps), and clear-cut area (zone where trees were completely removed), affect the early growth performance of artificially regenerated oak stands in Central Europe. Seedling height, root collar diameter, sturdiness quotient (SQ), and light availability (via hemispherical photography) were assessed. The most favorable growth occurred in gaps and under-canopy sites, where light intensity ranged from 44% to 57%, and seedlings reached mean heights of 148.7 cm and 143.4 cm, respectively. In contrast, seedlings in clear-cut and inter-gap areas exhibited lower growth and higher SQ values, suggesting lower seedling stability. In these areas, the average seedling height was 127.2 cm in clear-cut opening and 137.9 cm in inter-gap area. These sites also had the highest light intensity, amounting to 100% and 89.85% of total incident radiation, respectively. Growth performance was also affected by cardinal direction, except within gaps. This study highlights the importance of microsite selection in oak regeneration and demonstrates how optimizing light conditions can enhance reforestation success and climate resilience. These findings contribute to sustainable forest management practices aimed at supporting adaptive strategies in temperate ecosystems facing climate change. Full article

The degradation of Mediterranean forest ecosystems, such as holm oak forests, has intensified in recent decades due to climate change, forest fires, and deforestation, compromising the natural regeneration of the soil. In this context, it is essential to apply sustainable strategies to restore soil and promote plant growth, thus helping the regeneration of the ecosystem. One of these strategies is the use of plant growth-promoting bacteria (PGPB) in combination with recovered organic waste, such as that from wastewater treatment plants (WWTPs). In this paper, the effects of a biofertilizer formulated from WWTP residue (with and without sterilization), supplemented with two PGPB strains (Bacillus pretiosus and Pseudomonas agronomica), on the growth of holm oak seedlings (Quercus ilex) were evaluated under field conditions. A study was carried out on its nutritional composition, the rhizospheric cenoantibiogram, and its functional and taxonomic microbial diversity. Nine combinations of chemical and biological treatments using irrigation with water as a control were compared. The results showed that treatments with WWTP, especially combined with PGPB strains, promoted greater plant development and a lower seedling mortality rate. The cenoantibiogram exhibited a reduction in the resistance profile in soils treated with biofertilizer, without affecting soil microbial diversity, which remained unaltered across treatments, as confirmed by metagenomic and functional diversity analyses. Overall, this research reinforces the viability of the use of biofertilizers recovered from WWTP as an ecological and effective strategy for the recovery of degraded holm oak forests. Full article

Soils act as sources or sinks for three major greenhouse gases (CO₂, CH₄, and N₂O). Approximately 20% of global CO₂ emissions are released from soils through the soil respiration process. Soil respiration (soil CO₂ emission) can account for over 85% of ecosystem respiration. The aim of this study was to compare managed and unmanaged stands of pedunculate oak (Quercus robur L.) in order to investigate the impact of forest management on soil CO₂ emissions. We selected one managed and two unmanaged stands. The first stand (S1) represents a managed middle-aged stand, which is the optimal stage of development. The second stand (S2) belongs to the over-mature stage of development in an old-growth oak forest, while the third stand (S3) belongs to the decay stage of development in an old-growth oak forest. The closed chambers method was used for air sampling and the air samples were analyzed using gas chromatography (GC). Multiple regression models that include soil temperature (ST), soil moisture (SM), and their interaction provide a better explanation for variation in soil CO₂ emission (SCDE) (higher R² values) compared to regression models that only involve two variables (ST and SM). The study showed that SCDE in the decay stage of old-growth forest (S3) was significantly lower (p < 0.001) compared to the other two stands (S1 and S2). S3 is characterized by very low canopy cover and intensive natural regeneration, unlike S1 and S2. However, there were no significant differences in SCDE between the managed middle-aged stand (S1) and the over-mature (old-growth) stand (S2). Over a long-term rotation period in pedunculate oak forests, forest management practices that involve the periodic implementation of moderate silvicultural interventions can be deemed acceptable in terms of maintaining the carbon balance in the soil. Full article

Holm oak groves of Quercus ilex subsp. ilex are one of the most characteristic environmental elements of the Cantabrian strip of the Iberian Peninsula. The Cantabrian holm oak forest does not have a clear origin. There is a possibility that it has a relict character, and it could also respond more to human activity over the last 10,000 years. Nowadays, it is a rare, scarce, and finicultural forest in this demarcation, but it provides many ecosystem services. To carry out a comparative analysis and assessment of its potential as Green Infrastructure and of its coastal facies (Urdaibai, Bizkaia), 10 random and stratified inventories were carried out. These plots were monitored regularly for more than 2 years and in seasonal visits to avoid phenological bias. The resulting synthetic syninventories were then assessed according to the LANBIOEVA (Landscape Biogeographical Evaluation) Methodology, which has been applied for more than 35 years in different ecosystems and landscapes at a global scale. Scores for various parameters related to ecosystem services are of high conservation interest, and the cultural services are medium to high. Concerning conservation priority, the low records of the three threat parameters result in mean values that are in the first quartile for this parameter, which attests to a good level of conservation. The conclusion is clear: the Biosphere Reserve status has had a positive influence on the proper management and conservation of the Cantabrian holm oak forest and its associated ecosystem services. However, certain threats that still weigh on this ecosystem need to be addressed. Full article

Human activities are increasing the occurrence of megafires that alter ecological dynamics in forest ecosystems. The objective of this study was to understand the impacts of a 610 km² megafire on patterns of tree regeneration and herbivory across three forest types (aspen/fir, oak/maple, and pinyon/juniper). Seventeen transect pairs in adjacent burned/unburned forest stands (6 aspen/fir, 5 oak/maple, and 6 pinyon/juniper) were measured. Sapling density, meristem removal, and height were measured across the transect network over a three-year period from 2019 to 2021. Tree species able to resprout from surviving roots (oak and aspen) generally responded positively to fire while species that typically regenerate by seeding showed little post-fire regeneration. Browse pressure was concentrated on deciduous tree species and was greater in burned areas but the effect diminished over the three-year study period. Meristem removal by herbivores was below the critical threshold, resulting in vertical growth over time. Our results indicate that forest regeneration within the megafire scar was generally positive and experienced sustainable levels of ungulate browsing that were likely to result in forest recruitment success. Full article

The escalating threat of climate-driven wildfires, land abandonment, wildland–urban interface expansion, and inadequate forest management poses an existential challenge to Mediterranean oak ecosystems, for which traditional fire suppression has proven insufficient. This paper presents a combination of integrated fire management (IFM) and closer-to-nature forest management (CTNFM) in a representative mixed Pyrenean oak (Quercus pyrenaica) forest at Quinta da França (QF), in Portugal. It is structured around three main objectives designed to evaluate this pioneer integrated approach: (1) to describe the integration of IFM and CTNFM within an agro-silvo-pastoral landscape; (2) to qualitatively assess its ecological, operational, and socio-economic outcomes; and (3) to quantitatively evaluate the effectiveness of two key nature-based solutions (NbSs), that is, prescribed burning and planned grazing, in reducing wildfire risk and enhancing forest resilience and biodiversity. By strategically combining proactive fuel reduction with biodiversity-oriented silviculture, the QF case provides a replicable model for managing analogous Mediterranean forested areas facing similar risks. This integrated approach supports forest multifunctionality, advancing both prevention and adaptation goals, and directly contributes to the ambitious targets set by the European Union’s New Forest and Biodiversity Strategies for 2030, marking a significant step towards a more sustainable and fire-resilient future for such Mediterranean landscapes. Full article

Understanding species composition and forest dynamics is essential for predicting biomass productivity and informing conservation in tropical montane ecosystems. We evaluated floristic, demographic, and biomass changes in eighteen 0.1 ha permanent plots in the Colombian Sub-Andean forest, including both primary (ca. 60 y old) and secondary forests (ca. 30 years old). Two censuses of individuals (DBH ≥ 2.5 cm) were conducted over 7–13 years. We recorded 516 species across 202 genera and 89 families. Floristic composition differed significantly between forest types (PERMANOVA, p = 0.001), and black oak (Trigonobalanus excelsa Lozano, Hern. Cam. & Henao) forests formed distinct assemblages. Demographic rates were higher in secondary forests, with mortality (4.17% yr), recruitment (4.51% yr), and relative growth rate (0.02% yr) exceeding those of primary forests. The mean aboveground biomass accumulation and the rate of annual change were higher in primary forests (447.5 Mg ha⁻¹ and 466.8 Mg ha⁻¹ yr⁻¹, respectively) than in secondary forests (217.2 Mg ha⁻¹ and 217.2 Mg ha⁻¹ yr⁻¹, respectively). Notably, black oak forests showed the greatest biomass accumulation and rate of change in biomass. Annual net biomass production was higher in secondary forests (8.72 Mg ha⁻¹ yr⁻¹) than in primary forests (5.66 Mg ha⁻¹ yr⁻¹). These findings highlight the ecological distinctiveness and recovery potential of secondary Sub-Andean forests and underscore the value of multitemporal monitoring to understand forest resilience and assess vulnerability to environmental change. Full article

Climatic oscillations in the Quaternary are altering the performance of angiosperms, while the species’ distribution is regarded as a macroscopic view of these spatial and temporal changes. Oaks (Quercus L.) are important tree models for estimating the abiotic impacts on the distribution of forest tree species. In this study, we modeled the past, present, and future suitable habitat for two varieties of deciduous oaks (Quercus serrata and Quercus serrata var. brevipetiolata), which are widely distributed in China and play dominant roles in the local forest ecosystem. We evaluated the importance of environmental factors in shaping the species’ distribution and identified the “wealthy” habitats in harsh conditions for the two varieties. The ecological niche models showed that the suitable areas for these two varieties are mainly concentrated in mountain ranges in central China, while Q. serrata var. brevipetiolata is also widely distributed in the middle-east mountain range. The mean temperature of the coldest quarter was identified as the critical factor in shaping the habitat availability for these two varieties. From the last glacial maximum (LGM) to the present, the potential distribution range of these two sibling species has obviously shifted northward and expanded from the inferred refugia. Under the optimistic (RCP2.6), moderate (RCP 4.5)-, and higher (RCP 6.0)-concentration greenhouse gas emissions scenarios, our simulations suggested that the total area of suitable habitats in the 2050s and 2070s will be wider than it is now for these two varieties of deciduous oaks, as the distribution range is shifting to higher latitudes; thus, low latitudes are more likely to face the risk of habitat losses. This study provides a case study on the response of forest tree species to climate changes in the north temperate and subtropical zones of East Asia and offers a basis for tree species’ protection and management in China. Full article

The common oak (Quercus robur L.), though ecologically important and long-lived, has declined in Northern Europe due to historical land use and conifer-dominated forestry. In Latvia, where its distribution is limited, oaks support a rich biodiversity through features like tree-related microhabitats (TreMs) and diverse epiphytic communities. This study compared TreM and epiphyte diversity between planted mature oaks and relict champion oak trees across 16 forest stands. Epiphyte species were recorded using fixed-area frames on tree trunks, and TreMs were categorized following a hierarchical typology. Champion trees hosted significantly more TreMs and a greater variety, including 10 unique TreMs. While overall epiphyte diversity indices did not differ significantly, champion trees supported more specialist and woodland key habitat indicator species. The findings underscore the ecological value of legacy trees, which provide complex habitats essential for specialist taxa and indicators of forest continuity. Conserving such trees is vital for maintaining forest biodiversity and supporting ecosystem resilience in managed landscapes. Full article