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Quercus suber woodlands are widely distributed around the Western Mediterranean basin. Although assumed well-adapted to recurrent seasonal droughts, water availability during critical phases can limit Q. suber crown development and, consequently, photoassimilate production and growth. This work aims to assess the relationships between climate conditions and seasonal and interannual variation of multiple vegetative and reproductive growth traits in Q. suber and identify possible mechanisms governing within-tree competition for resources and trade-offs between vegetative and reproductive growth. Data collection occurred between 2010 and 2019 and involved the monthly monitoring of reproductive and vegetative phenology, stem radial growth, and litterfall collection in a Q. suber woodland in central Portugal. Winter and autumn precipitation reductions (20 and 30%, respectively) during 2015–2019 resulted in a 23% decrease in leaf biomass production (compared to 2010–2014). Results show that mean March temperatures have a pivotal role in balancing vegetative/reproductive biomass investment, being positively correlated with the growth of vegetative structures (r = 0.81) and negatively correlated with acorn production (r=-0.83). PCA results also confirm the existence of competitive interaction between reproductive and vegetative growth in Q. suber trees, with mast cropping years resulting in reductions in annual leaf biomass production (26%). Dry years affected annual stem radial growth negatively (ca. 48%), reducing the period of phellogen activity and anticipating annual radial growth peaks by two months, consequently shortening the window for a safe cork extraction. Our results provide valuable information to adapt the management of Q. suber woodlands to ongoing environmental changes and contribute to ecosystem sustainability. [ABSTRACT FROM AUTHOR]

This study focuses on the effect of differences in acorn dropping time on seedling establishment in two abundant Mediterranean oak species: Quercus ilex subsp. ballota and Q. suber. These species show extended seed dropping seasons (i.e., 4 to 5 months) and the fallen acorns thus experience variable conditions, including differences in climate and microclimate, as well as differences in biological interactions (mainly pre- and post-dispersal predation by insect larvae and rodents, respectively). We conducted two field experiments and a field survey on acorn infection by insect larvae and analysed the ability of early and late dropped acorns to achieve success (i.e., remaining healthy, germinating, and emerging as seedlings). The results indicated that pre- and post-dispersal predation of propagules changed over time. However, these factors had low effect on final seedling success. In opposition, warmer (i.e., autumn) conditions at acorn dropping and sowing time decreased seedling establishment in Q. suber, likely by a lack of cold stratification, while the conditions had no effect on Q. ilex subsp. ballota seedlings. We conclude that climate warming can selectively decrease the number of seedlings that are established in late springtime, before the onset of the characteristic Mediterranean summertime drought, thus negatively affecting the population dynamic in these species, which exhibit a high level of physiological dormancy as they depend on cold conditions to maximise acorn germination and epicotyl emergence. [ABSTRACT FROM AUTHOR]

Turkey oak (Quercus cerris L.) is one of the most ecologically and economically significant deciduous tree species in the Central and Southeast European regions. The species has long been known to exhibit high levels of genetic and phenotypic variation. Recent climate response predictions for Turkey oak suggest a significant distribution extension in Europe under climate change. Since Turkey oak has relative drought-tolerant behaviour, it is regarded as a potential alternative for other forest tree species during forestry climate adaptation efforts, not only in its native regions but also in Western Europe. For this reason, the survey of existing genetic variability, genetic resources, and adaptability of this species has great significance. Next-generation sequencing approaches, such as ddRAD-seq (Double digest restriction-site associated DNA sequencing), allow the attainment of high-resolution genome-wide single nucleotide polymorphisms (SNPs). This study provides the first highly variable genome-wide SNP data for Turkey oak generated by ddRAD-seq. The dataset comprises 17 607 de novo and 26 059 reference mapped SNPs for 88 individuals from eight populations, two from Bulgaria, one from Kosovo, and five from Hungary. Reference mapping was carried out by using cork oak's (Quercus suber L.) reference genome. The obtained high-resolution genome-wide markers are suitable for investigating selection and local adaptation and inferring genetic diversity, differentiation, and population structure. The dataset is accessible at: https://doi.org/10.5281/zenodo.8091252 [ABSTRACT FROM AUTHOR]

Climate change is having an impact on locally adapted species, including the cork oak (Quercus suber L.), a key tree species in the Mediterranean region especially due to its role in carbon sequestration. Notably, the Maâmora forest in Morocco stands as the largest forest in the Mediterranean basin with the highest diversity compared to similar forests across Morocco. In this study, we genotyped 240 samples from natural populations of cork oak in the Maâmora forest using seven microsatellite markers, to investigate signatures of local adaptation. Using a genomic scan approach, we identified outliers loci experiencing divergent natural selection pressures, which were later correlated with climatic, edaphic, and geographic conditions of the Maâmora forest. Statistical analysis of the data shows a high allelic variation. The detection of outliers, carried out using BayeScan v2.1 software, revealed the presence of two significant outliers loci ZAG20-171 (qvalue = 0.0004) and MSQ4-211 (qvalue = 0.04). The result of the environmental association analysis revealed a significant correlation between locus ZAG20-171 with mean diurnal range, isothermality, annual precipitation, precipitation of the driest month, precipitation of the wettest quarter and altitude. This work aims to help understanding the genetic basis of adaptation in Q. suber L., and thus the selection of suitable provenances for further breeding efforts. [ABSTRACT FROM AUTHOR]

Local terrain or microsite conditions influence the development of trees, particularly at early ages. These conditions might be described by edaphic or topographic variables. We mapped soil and topographic variables from four even-aged and even-spaced cork oak plantations located in two climatically distinct Portuguese regions. The major goal of this research was to understand the relation between soil and topographic fine-scale conditions and tree growth expressed by diameter without cork annual growth (idu). The methodology consisted in (1) analysing the spatial variability and autocorrelation of idu; (2) modelling idu with ordinary least squares (OLS) regressions; (3) comparing with spatial modelling of idu, incorporating spatial autocorrelation. The driest stands A and B, exhibited weaker spatial autocorrelation, distributed in smaller clusters (R2 < 0.03, OLS models), while stands C (R2 = 0.18, OLS models) and D (R2 = 0.11, OLS models) showed higher predictive capacity. Spatial models increased R2 scores, keeping most variables from OLS models and accounting for spatial autocorrelation. A + B + C + D OLS model obtained an R2 = 0.34 and respective spatial model R2 = 0.58. Apparent electrical conductivity at 0.5 (ECa0.5) and 1 m of soil depth, slope, elevation and topography position index were included as predictors (OLS), but only ECa0.5, slope and elevation were selected in the spatial model. Models were fitted using average to high productivity stands and should be used cautiously outside this range. Local terrain conditions determine the growth of young cork oak trees. Mapping soil and topographic variables before establishing new plantations may identify limiting microsite conditions where using cork oak species is not suitable due to low growth rates expectations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cork oak woodlands are socio-ecosystems recognized as biodiversity hotspots, a fundamental economic source for companies and local communities as well as an identitarian landscape for residents and visitors. Cork oak woodlands, however, are facing tree mortality and lack of regeneration. Considering the oak decline scenario, we present Iberian cork oak montado/dehesa as a socio-ecosystem facing climate change, management transformations, local knowledge crisis and social uncertainty. We review montados/dehesas research through time and by different scholar perspectives. We defend that from an interdisciplinary and transdisciplinary perspective, including the experience and evidence observed in terrain, debate should be stimulated, and novel conceptual approaches may contribute to finding solutions. We argue that the confluence of ecology, genetics, anthropology and local knowledge can be explored to unveil the complexities and the challenges of these socio-ecosystems and contribute to prevent and mitigate threats to it. We propose a methodological approach built together with scientists, managers and workers, that can explore oak translocations, socio-ecological interactions models, knowledge transfer and other ways to overcome Iberian cork oak woodlands socio-environmental crisis. [ABSTRACT FROM AUTHOR]

Silvopastoral systems are widely used for ecological vegetation restoration in fragile areas. As the main landform of western Henan, the low hilly areas are experiencing water and soil loss because of human activities. However, the effect of silvopastoral systems on soil nutrients in low hilly areas has not been well studied. To address this issue, we established a silvopastoral experiment in the low hilly area of western Henan province in 2011, where four plots of pure forest of poplar (Populus simonii, PS), oriental thuja (Platycladus orientalis, PO), Chinese cork oak (Quercus variabilis, QV) and false acacia (Robinia pseudoacacia, RP) was planted on a natural wasteland; perennial alfalfa (Medicago sativa, MS) was intercropped with these pure forest plots as silvopastoral treatments, i.e., PS-MS, PO-MS, QV-MS and RP-MS; one plot of natural wasteland as CK. In 2018, 2019 and 2020, we examined the soil total carbon (TC) and total nitrogen (TN) of different vegetation restorations. Results showed that the silvopastoral treatments (PO-MS, QV-MS and RP-MS) generally increased the TC and TN (by ~ 53% and ~ 51% in 2018, ~ 66% and ~ 49% in 2019, and ~ 66% and ~ 67% in 2020, respectively) compared to the pure forest treatments, and were also higher than the M and PS-MS. The change in relative TC and TN between downslope and upslope positions is higher in PS and PO, lower in RP compared to the PS-MS and PO-MS, RP-MS respectively, and non-different between QV and QV-MS. In summary, soil nutrient properties are generally higher but vary among the slope positions in the silvopastoral treatments compared to pure forest treatments in the low hilly area. [ABSTRACT FROM AUTHOR]

The effects of boiling water treatment on the physical properties of Quercus variabilis virgin cork (Qv VC) were examined and compared with those of Quercus suber reproduction cork (Qs RC). The water treatment was conducted at 100 °C for 1 h. Qv VC showed a significantly higher dimensional change in the three directions and lower weight loss than Qs RC by boiling water treatment. Untreated and boiled Qv VC showed higher density, air-dried moisture content, red/green (a*) and yellow/blue (b*) chromaticity, overall color change, shrinkage in all three directions, moisture adsorption on the entire surface, and swelling per 1% moisture content than untreated and boiled Qs RC. However, the lightness (L*) and water absorption on each surface were higher for Qs RC than for Qv VC. Moisture adsorption on each surface was comparable before and after heat treatment for both species. After boiling water treatment, the air-dried moisture content, dimensions, volume shrinkage, water absorption, and moisture adsorption on each surface and the entire surface increased, whereas L*, a*, b*, and swelling per 1% moisture content decreased. The results of the present study could be useful for further utilization of Qv cork growing in Korea. [ABSTRACT FROM AUTHOR]

Climate change is favouring the northward shift of Mediterranean oaks which are expanding their ranges at their leading edges. However, Mediterranean oaks have recalcitrant seeds (desiccation sensitive) that do not form seed banks, depending on climate conditions after seed fall and interactions between genetic determinants to germinate. Here we investigate the potential adaptation of Quercus suber range-wide populations to increasing spring temperature in germination timing and rates. We sowed 701 acorns from 9 populations from 10 mother trees each, at 15, 20 and 25 °C and monitored germination daily during 90 days. We modelled germination timing through Cox's proportional-hazards models, assessed populations' adaptation to spring temperature transfer distances and quantified the effect of acorn mass and storage duration on germination probability and timing with fixed-effects models. We used the mixed-effects models to predict germination climatic niches under current and RCP 8.5 2080 scenarios. Differences in germination timing were due to both the population origin and temperature treatment; germination rates showed a sub-optimality towards warmer-than-origin temperatures. The timing of germination decreased along with spring temperatures increment, with germination in 2080 predicted to occur 12 days earlier than to date in central Iberia. Warmer spring temperatures significantly accelerate the germination of recalcitrant Mediterranean species, which could alter seedlings' developmental environment and ultimately populations' regeneration and species composition. As such, germination timing should receive more attention from scientists and stakeholders and should be included in forest vulnerability assessments and assisted migration programs aiming at long-term forest regeneration to adapt forests to climate change. [ABSTRACT FROM AUTHOR]

Cork oak (Quercus suber L.) is an essential species of the Mediterranean region. In Morocco, it represents a source of life and is a noble species for many populations. The Maâmora forest, situated in Morocco, is recognized as the largest forest in the Mediterranean basin and displays the highest diversity compared to other forests in its distribution area. This study aimed to establish a genetic database of 240 individuals from Maâmora forest using seven SSR markers. Through a series of statistical analyses, we determined the level of diversity and genetic structure and created a core collection. Statistical analysis of the data showed a high degree of allelic variation, generating 47 alleles with an average of 6.71 alleles per locus. Furthermore, a high percentage of polymorphisms and a high Shannon index were observed. Intra-population genetic diversity was found to be high (86%) compared to inter-population diversity (14%). A low level of genetic differentiation (Gst = 0.12) and high gene flow were identified, consistent with the results obtained from the analysis of molecular variance (AMOVA). This suggests a possible capacity for the species to adapt to environmental conditions. A core collection of 18 genotypes was constructed, which included all the private alleles that were detected in this study. This core collection exhibited similar and crucial diversity to that identified in the initial collection, as verified by a series of genetic diversity and structural analyses. This research advocates populations and individuals for further studies on adaptation in order to improve and conserve this valuable resource in the future. [ABSTRACT FROM AUTHOR]

Suberin, a complex biopolymer, forms a water- and gas-insoluble barrier that protects the inner tissues of plants. It is abundant in tree bark, particularly in the cork oak Quercus suber. Anatomically, fossil bark has been described since the Devonian. However, its distinctive constituent suberin has not yet been reported from the fossil record. Here we present unambiguous chemical evidence for intact suberin from the bark of a middle Eocene monkeyhair tree from Geiseltal, eastern Germany. High-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC–ESI-MS) detected constituents of suberin in the outer layer the fossil monkeyhair tree, which confirms previous morphological interpretation of this tissue as bark, and chemically differentiates this layer from the two tissues of the inner layer. Notably, this is the first study with compelling chemical evidence for suberin in fossil bark. Fluorescence microspectroscopy additionally supports the presence of suberin. Fossilization conditions in the Eocene Geiseltal deposit were likely mild, with low moisture and temperatures, contributing to the remarkable preservation of bark and inner laticifer mats of the monkeyhair trees growing there 45 million years ago. [ABSTRACT FROM AUTHOR]

The crystalline characteristics, chemical composition, and thermal decomposition of elements in Quercus variabilis (Qv) virgin cork were investigated using X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric methods, respectively, and compared with those of elements in Quercus suber (Qs) reproduction cork. Samples of cork elements, including pure cork, lenticular filling tissue (LFT), dark-brown zone (DBZ), and sclereids, were prepared. The X-ray diffractograms of pure cork from both species showed an amorphous pattern, whereas those of LFT, DBZ, and sclereid showed a crystalline cellulose I pattern. The relative crystallinity of DBZ was significantly lower than that of Qv LFT and the sclereid. In the FTIR spectra, Qv pure cork tended to show weaker band intensities for the suberin, lignin, and carbohydrate compounds than Qs pure cork. The pure corks of both species showed stronger suberin bands than LFT, DBZ, and the sclereid. In the thermogravimetric analyses, the peaks of hemicellulose and cellulose decomposition in both pure corks were weaker than those in LFT, DBZ, and sclereid, whereas the peaks of suberin decomposition in both pure corks were the highest among all elements. [ABSTRACT FROM AUTHOR]

Chloroplast genome diversity in cork oak (Quercus suber) is characterised by the occurrence of haplotypes that are akin to those found in other Mediterranean oak species, particularly in Q. ilex and Q. rotundifolia, suggesting the possible presence of an introgressed chloroplast lineage. To further investigate this pattern, we reconstructed chloroplast haplotypes by sequencing four chloroplast markers (cpDNA), sampled across 181 individuals and 10 taxa. Our analyses resulted in the identification of two diversified chloroplast haplogroups in Q. suber, corresponding to a geographically widespread lineage and an Afro-Iberian lineage. Time-calibrated phylogenetic analyses of cpDNA point to a Miocene origin of the two haplogroups in Q. suber, suggesting that the Afro-Iberian lineage was present in cork oak before the onset of glaciation periods. The persistence of the two haplogroups in the western part of the species distribution range may be a consequence of either ancient introgression events or chloroplast lineage sorting, combined with different fixation in refugia through glaciation periods. Our results provide a comprehensive insight on the origins of chloroplast diversity in these ecologically and economically important Mediterranean oaks. [ABSTRACT FROM AUTHOR]

Context: The management of Portuguese agroforestry landscapes is currently focused on specialised cork and cattle production. Sustainable landscape management is increasingly discussed as an effective option to foster the multifunctionality of these landscapes. Such management requires consideration of multiple values connected to the landscape and to the products stemming from it. Objectives: The aim of this study is to (1) assess the importance of specific values related to cork and to the cork production landscapes, (2) analyse how values differ across the value chain actors, and (3) compare the types of values associated to cork and the cork production landscapes. Methods: We combine value chain analysis with the concept of plural valuation in order to illuminate the values amongst value chain actors. We conducted interviews with 62 actors divided across the value chain using a semi-structured questionnaire. Results: We found that a broad range of instrumental, intrinsic and relational values were expressed by our respondents. Our results show an imbalance between the perception of the ecosystem health expressed by actors involved in the industrial transformation of cork compared to those directly involved with the landscape. This imbalance shows the necessity to find a common management ideal for cork production landscapes favouring multifunctionality. Conclusions: Our study shows the relevance of considering plural values when planning and implementing sustainable landscape management. Integrated into a landscape approach, value chain analysis is useful in reaching actors in order to uncover different points of view towards a single landscape. Our study suggests that focusing on the multifunctional nature of the cork production landscapes may be key in ensuring a sustainable future for this social-ecological system. [ABSTRACT FROM AUTHOR]

Cork oak (Quercus suber L.) is an ecologically and economically important evergreen tree species native to the Mediterranean region and widespread in southwest Europe and northwest Africa. An improved genome assembly of cork oak using a combination of Illumina and PacBio sequencing is presented in this study. The assembled genome contains 2351 scaffolds longer than 1000 bp, accounting for 765.7 Mbp of genome size, L90 of 755, and a N50 of 1.0 Mbp, with 40,131 annotated genes. The repetitive sequences constitute 53.6% of the genome. The genome sequences of chloroplast and mitochondrion were determined for the first time, with a genome size of 161,179 bp and 531,858 bp, respectively. Phylogenetic analysis based on complete chloroplast genome sequence showed that Q. suber is closely related to Quercus variabilis, two cork-producing species with commercial use. All data generated are available through the public databases, being ready to be used without restrictions. This study provides an improved nuclear genome assembly together with the organelle genomes of cork oak. These resources will be useful for further breeding strategies and conservation programs and for comparative genomic studies in oak species. [ABSTRACT FROM AUTHOR]

The challenges of this work focus on better understanding combustion characteristics and their importance to fire hazard by performing thermogravimetric analysis (TGA). The ultimate goal is to provide a methodology for determining the most relevant indices for a robust fire hazard classification of the species. One of the principles of this methodology is the use of a linear regression method for determining the indices and the activation energy. To achieve this scope, chemical, thermal and kinetic analysis will be performed. Nine combustion indices were calculated and compared to assess combustion characteristics such as ignition, combustion and burnout. Experiments were carried out at three heating rates of 10, 15 and 20 °C min−1 under air atmosphere. A selection of forest materials frequently devastated by wildfire, i.e., Quercus pubescens (QP), Quercus suber (QS), Olea europaea (OE) and Genista Salzmannii needles (GSN), were studied. The TG-DTG curves have shown that the combustion process consists of two stages: devolatilization and char oxidation. The whole process was controlled by the release of volatile gases. According to the relative linearized (RL) index of spontaneous ignition, the samples were ordered as follows: OE > GSN ≥ QS > QP. OE appears to be the most reactive and prone to spontaneous ignition compared to the other samples. The same order was achieved for the combustion characteristic index and, approximately, for the integrated flammability. On the other hand, the average Ea at the low temperature stage of the combustion process was low for GSN (147 ± 9 kJ mol−1) and OE (159 ± 4 kJ mol−1) and high for QP (179 ± 14 kJ mol−1) and QS (174 ± 3 kJ mol−1). Finally, this work provides valuable insight into the relationship between chemical properties and combustion indices and the components that make some indices more effective than others. [ABSTRACT FROM AUTHOR]

The biocatalysis of β-myrcene into value-added compounds, with enhanced organoleptic/therapeutic properties, may be performed by resorting to specialized enzymatic machinery of β-myrcene-biotransforming bacteria. Few β-myrcene-biotransforming bacteria have been studied, limiting the diversity of genetic modules/catabolic pathways available for biotechnological research. In our model Pseudomonas sp. strain M1, the β-myrcene catabolic core-code was identified in a 28-kb genomic island (GI). The lack of close homologs of this β-myrcene-associated genetic code prompted a bioprospection of cork oak and eucalyptus rhizospheres, from 4 geographic locations in Portugal, to evaluate the environmental diversity and dissemination of the β-myrcene-biotransforming genetic trait (Myr+). Soil microbiomes were enriched in β-myrcene-supplemented cultures, from which β-myrcene-biotransforming bacteria were isolated, belonging to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Sphingobacteriia classes. From a panel of representative Myr+ isolates that included 7 bacterial genera, the production of β-myrcene derivatives previously reported in strain M1 was detected in Pseudomonas spp., Cupriavidus sp., Sphingobacterium sp., and Variovorax sp. A comparative genomics analysis against the genome of strain M1 found the M1-GI code in 11 new Pseudomonas genomes. Full nucleotide conservation of the β-myrcene core-code was observed throughout a 76-kb locus in strain M1 and all 11 Pseudomonas spp., resembling the structure of an integrative and conjugative element (ICE), despite being isolated from different niches. Furthermore, the characterization of isolates not harboring the Myr+-related 76-kb locus suggested that they may biotransform β-myrcene via alternative catabolic loci, being thereby a novel source of enzymes and biomolecule catalogue for biotechnological exploitation. Key points: • The isolation of 150 Myr+bacteria hints the ubiquity of such trait in the rhizosphere. • The Myr+trait is spread across different bacterial taxonomic classes. • The core-code for the Myr+trait was detected in a novel ICE, only found in Pseudomonas spp. [ABSTRACT FROM AUTHOR]

This correction notice addresses an error in Table 1 of an article published in New Forests. The incorrect value for Annual Precipitation was mistakenly displayed in the row for Mean Temperature, and vice versa. The correct values have been provided, and the interpretation of the results remains unchanged. The publisher, Springer Nature, maintains a neutral stance on jurisdictional claims and institutional affiliations. The article was authored by Paulo Neves Firmino, Joana Amaral Paulo, António Lourenço, Margarida Tomé, and Manuel Campagnolo. [Extracted from the article]

Wood-boring insects are considered potential contributing/inciting factors to oak decline. Cerambyx cerdo (Cc) and C. welensii (Cw) are two sympatric oak-living large sapro-xylophagous longhorn beetles with different pest/legal status, whose larvae bore into living wood of healthy/decayed trees, and whose impact has increased alarmingly in recent years. We conducted a regional-scale multi-year (2017–2020) field study to model Cc and Cw distribution and to explore species-specific occupancy-abundance patterns. Records were obtained with 1650 feeding traps placed throughout the region of Extremadura (SW Spain) (41,634 km2) in holm, cork and pyrenean oak woodlands. Catch number (a proxy of abundance) was analysed through GLMMs, LMs and geostatistical interpolation (IK algorithm) to generate catch probability maps. Catch number was extremely variable between trees (traps), stands and years (Cc: 0–252, Cw: 0–219 adults/trap) with no repulsive interspecific association at the tree scale. Explanatory factors in the models (species, sex, year and host oak) and several interactions among them significantly affected catch number. As a whole, Cw was more abundant than Cc, but catch number greatly depended on host tree (Cw: cork > holm > pyrenean oak, Cc: holm > cork > pyrenean oak). Occupancy-abundance patterns were positive with significant occupancy x species interaction. Niche breadth was more than double in Cw (Levins' BA = 0.42) than in Cc (BA = 0.19) and niche overlap almost complete (Pianka's O = 0.98). Our large-scale pioneer study shows that Cc and Cw are widespread in SW Spain, but with huge host-mediated intra- and interspecific geographic variation in abundance, which has critical implications in population management/control strategies. [ABSTRACT FROM AUTHOR]

Cork rings have been extensively used in dendroecological studies of the Mediterranean evergreen cork oak (Quercus suber L.). Through measurements of cork-ring width only, strong relationships have been found between cork-ring widths and climate parameters. To our knowledge, cork-ring density, which is an important cork quality attribute, has never been used in any dendroecological study to explore physiological responses of the cork oak to climate change. In this study, we measured cork-ring width and density over 50 years (1962–2013), corresponding to five consecutive cork harvests, and analyzed their inter-annual fluctuations in eight trees from two different sites, a wetter peneplain area (Benavente) and a drier mountainous area (Grândola). Our results revealed a statistically significant correlation between cork-ring width and density (p < 0.05) at both sites; however, it was negative (r =− 0.261) and relatively weaker at Benavente, and positive at Grândola (r = 0.410). Moreover, a direct relationship between cork density and spring–summer temperature was found only at Grândola. Here, cork growth sensitivity to inter-annual variability of precipitation and temperature in summer-autumn of the current growth year (p < 0.01) was the highest and, respectively, positive and negative. We conclude that in drier Mediterranean environments, summer drought stress might negatively affect both cork growth and density, by changing tree physiological processes involved in cork formation, resulting in narrower and denser cork rings. Considering scenarios of future climate change effects in Southern Europe, in particular the longer drought periods and rising temperatures, it seems that both cork yield and cork density will be affected, with implications on cork quality. [ABSTRACT FROM AUTHOR]

Biscogniauxia mediterranea has long been recognized as the causal agent of charcoal canker disease of Quercus species. It has been considered to be highly involved in cork oak decline in the Mediterranean region. In this study, a collection of B. mediterranea strains was isolated from declining cork oak trees in three cork oak forests in Tunisia. Among them, nine representative isolates were subjected to genetic polymorphism analysis based on ITS and tef1-α sequences showing a highly significant haplotype diversity. Pathogenicity tests of these isolates revealed a highly pathogenic effect towards stems which differed significantly between isolates. Although, they were less aggressive toward leaves. Nevertheless, the Mantel test indicated the absence of a significant correlation between the genetic and pathogenic variability. [ABSTRACT FROM AUTHOR]

The article presents the correction for a article titled "Overexpression of Ginkbilobin-2 homologous domain gene improves tolerance to Phytophthora cinnamomi in somatic embryos of Quercus suber" published online on September 12, 2024.

Cork oak (Quercus suber), native to Mediterranean areas, is a plant of ecological and economical relevance, nevertheless, the effects of soil salinization on this species are currently unknown. We have investigated the physiological and biochemical impact of a high-salinity episode on young cork oak (Q. suber) plants. Besides the control (plants only irrigated with water), two experimental groups (irrigated once with a 300 mM NaCl solution) were analysed, one assessed at 24 h and the other at 6 days. Pigments (chlorophylls and carotenoids) were found increased at 24 h, but decreased at day 6 in salinity conditions. Sugars (glucose, sucrose, starch but not fructose) increased with stress (24 h and 6 days). Salinity conditions impaired photosystem II (PSII) photochemistry, mostly associated with decrease in Fv′/Fm′ and chlorophyll content (6 days). While hydrogen peroxide levels did not increase above control levels, lipid peroxidation increased, suggesting oxidative damage. In salinity conditions, superoxide dismutase and ascorbate peroxidase showed higher activity in the 24 h timepoint, whereas catalase activity increased at 24 h and 6 days. These observations reveal adaptations of Q. suber to high salinity, nevertheless, the decreased photosynthetic activity and oxidative damages observed suggest that additional studies are required to assess Q. suber adaptation to diverse salinity conditions. Moreover, these data provide more information for future programs of conservation and management of salinity areas in the Mediterranean region, and selection of salinity tolerant species. [ABSTRACT FROM AUTHOR]

Cork oak is a tree species with ecological importance that contributes to economic and social development in the Mediterranean region. Cork oak decline is a major concern for forest sustainability and has negative impacts on cork oak growth and production. This event has been increasingly reported in the last decades and seems to be related with climate changes. Biscogniauxia mediterranea is an endophytic fungus of healthy cork oak trees that turns into a pathogen in trees weaken by environmental stress. Understanding the drivers of B. mediterranea populations diversity and differentiation is expected to allow a better control of cork oak decline and preserve forest sustainability. Endophyte isolates from different cork oak forests were identified as B. mediterranea and their genetic diversity was evaluated using phylogenetic and microsatellite-primed PCR analyses. Genetic diversity and variability of this fungus was correlated with environmental/phytosanitary conditions present in forests/trees from which isolates were collected. High genetic diversity and variability was found in B. mediterranea populations obtained from different forests, suggesting some degree of isolation by distance. Bioclimate was the most significant effect that explained the genetic variability of B. mediterranea, rather than precipitation or temperature intensities alone or disease symptoms. These findings bring new implications for the changing climate to cork oak forests sustainability, cork production and quality. [ABSTRACT FROM AUTHOR]

Cork oak woodlands are highly biodiverse silvopastoral systems, economically and socially relevant to rural communities in many Mediterranean areas. The installation of legume-rich pasture mixtures became a common practice in these woodlands aiming to obtain higher productivity, to improve soil fertility, and to increase the amount of protein for forage. The predicted impacts of climate change will affect pasture productivity either by altering the biomass total amount or its seasonal productivity. We analysed an 8-years data series of meteorological variables and herbaceous biomass productivity collected in a certified cork oak ecosystem with a moderate tree density (177 trees ha−1) to investigate how understorey herbaceous biomass is affected by inter annual and seasonal climate variability. The field collections were carried out in two contrasting understorey management systems: a natural understorey vegetation (NU) subject to shrub clearing every 5 years, without grazing; and a sown improved pasture, installed in 2009, grazed by cattle (IP). Results have shown that herbaceous biomass productivity was on average 8 times higher in IP than in the NU most likely due to the positive effects of the initial fertilization and the legume rich seed composition which increased N soil availability. The main climatic driver explaining the biomass productivity was the cumulative precipitation from February to May. The proportion of grasses increased in response to drought with a pronounce decrease in legumes, regardless of the management system. Nonetheless, the NU system was more resilient to drought compared to IP suggesting a need to better understand the role and contribution of each native species to resistance, resilience and recovery to drought in order to improve future forage mixtures. These results may support better management decisions by forest producers which are mostly based on empirical procedures and might provide some directions for further studies. [ABSTRACT FROM AUTHOR]

Natural, semi-natural, and extensively managed oak woodlands and forests are prevalent across the world. These lands fulfil a range of ecosystem services, goods, and functions. Increasing natural and anthropogenic pressures impose threats to these lands. This paper first describes the Quercus genus and discusses management and mismanagement practices of oak systems. Then, the provisioning ecosystem services related with oak systems are reviewed, including: (1) oak's agroforestry and silvopasture systems for the production of food, pasture, and additional products; (2) browsing of oak leaves and acorns by livestock; (3) harvesting of oak wood for timber; (4) cork oak stripping, and the uses of cork; (5) acorn-based foods and beverages; and (6) others uses, such as the production of medicines and extraction of tannins for the leather industry. We discuss the multi-purpose and multi-functional nature of oak systems, and demonstrate how they diversify sources of income for local communities, resulting in improved economic and food security. Further, we show the important role of woodlands certification, aimed at protecting oak systems while ensuring environmental equity. Also, we demonstrate how providing of financial support for reforestation and afforestation schemes of degraded oak woodlands, could restore ecosystem functioning and reverse land degradation. Then, we stress the need to involve traditional knowledge in restoration schemes of degraded oak systems. Lastly, we demonstrate how policymaking and legislation regarding the oak's commercial plantations and farming systems could alleviate stresses imposed on the world's oak woodlands and forests by producing alternative sources of wood for the timber industry. [ABSTRACT FROM AUTHOR]

Background: Insect herbivory has profound impacts on ecosystem processes and services. Although many efforts have been made to recognize the main drivers of insect herbivory at different scales, the results are inconsistent. One likely reason is that studies have insufficiently captured the spatially heterogeneous factors such as soil type and forest stratum within the stand that may significantly affect insect herbivory. In particular, there is a lack of studies that address the detailed spatial patterns of insect herbivory which are influenced by these factors. Methods: We measured the detailed spatial patterns of insect herbivory on cork oak (Quercus variabilis Bl.) in response to soil type (gravel soil and loam) and forest stratum (the upper, lower, and sapling stratum), and correlated these patterns with a set of influencing factors (litter coverage, coverage of shrubs and herbs, soil nutrients, soil moisture, and leaf traits) in a forest landscape. Results: Generally, insect herbivory was spatially heterogeneous within stands. Herbivory was significantly lower in gravel soil areas than in loam soil areas and the highest herbivory occurred in the lower stratum. However, there were also 41 individual plots in which the highest herbivory occurred in the upper stratum and 29 plots in which the highest herbivory occurred in the sapling stratum. There were significant differences in soil nutrient and water status between soil types, but no significant differences in leaf traits. The effects of forest stratum on leaf traits were also inconsistent with those on insect herbivory. Conclusions: Leaf traits may not be the main factors influencing insect herbivory in the field. Soil type may have major effects on herbivory patterns by influencing litter coverage while higher coverage of shrubs and herbs may reduce herbivory in the sapling stratum. These findings may advance our understanding of tree-herbivore interactions in real-world situations and have important implications for the sustainable management of forest ecosystems. [ABSTRACT FROM AUTHOR]

Although forest areas have been growing in Europe, some forest types have been declining regionally. Since the 1980 s, there have been reports of defoliation and mortality in evergreen oak woodlands of the Iberian Peninsula. However, long-term and large-scale trends of Iberian oak decline are still poorly understood. We quantified trends in canopy cover for cork oak (Quercus suber) and holm oak (Q. rotundifolia) woodlands in mainland Portugal for a 50 year period (1965 to 2015). We considered loss of canopy cover a proxy of forest degradation and asked how it changed over time, in association with human activity and climate. Between 1965 and 2015, both cork oak and holm oak canopy cover showed declining trends (57.9% and 71.1% of sampling points, respectively). Canopy cover dynamics, however, differed across time. Between 1965 and 1990, canopy cover gains (over 35% of sampling points) prevailed over losses (under 20%), with larger differences for cork oak than holm oak. Between 1990 and 2015, canopy cover losses (over 70% of sampling points) were much higher than gains (under 9%). Oak canopy cover decrease was associated with flatter areas (usually having more intensive land use) for both oak species, higher cattle numbers (holm oak only) and higher mean temperature (cork oak only). Contrastingly, loss of holm oak canopy cover seems to have occurred in less hot and dry regions that enable more intensive land uses. Active restoration is urgently needed to reverse the current decline in canopy cover in Mediterranean evergreen oak woodlands. [ABSTRACT FROM AUTHOR]

Knowledge about the vegetation history of Sardinia, the second largest island of the Mediterranean, is scanty. Here, we present a new sedimentary record covering the past ~ 8,000 years from Lago di Baratz, north-west Sardinia. Vegetation and fire history are reconstructed by pollen, spores, macrofossils and charcoal analyses and environmental dynamics by high-resolution element geochemistry together with pigment analyses. During the period 8,100–7,500 cal bp, when seasonality was high and fire and erosion were frequent, Erica arborea and E. scoparia woodlands dominated the coastal landscape. Subsequently, between 7,500 and 5,500 cal bp, seasonality gradually declined and thermo-mediterranean woodlands with Pistacia and Quercus ilex partially replaced Erica communities under diminished incidence of fire. After 5,500 cal bp, evergreen oak forests expanded markedly, erosion declined and lake levels increased, likely in response to increasing (summer) moisture availability. Increased anthropogenic fire disturbance triggered shrubland expansions (e.g. Tamarix and Pistacia) around 5,000–4,500 cal bp. Subsequently around 4,000–3,500 cal bp evergreen oak-olive forests expanded massively when fire activity declined and lake productivity and anoxia reached Holocene maxima. Land-use activities during the past 4,000 years (since the Bronze Age) gradually disrupted coastal forests, but relict stands persisted under rather stable environmental conditions until ca. 200 cal bp, when agricultural activities intensified and Pinus and Eucalyptus were planted to stabilize the sand dunes. Pervasive prehistoric land-use activities since at least the Bronze Age Nuraghi period included the cultivation of Prunus, Olea europaea and Juglans regia after 3,500–3,300 cal bp, and Quercus suber after 2,500 cal bp. We conclude that restoring less flammable native Q. ilex and O. europaea forest communities would markedly reduce fire risk and erodibility compared to recent forest plantations with flammable non-native trees (e.g. Pinus, Eucalyptus) and xerophytic shrubland (e.g. Cistus, Erica). [ABSTRACT FROM AUTHOR]

Cork is the most valuable non-wood product of the cork oak (Quercus suber L.). However, the cork oak sector may be at risk due to climatic and economic pressures on cork oak forests, affecting both the quantity and technological quality of products. At some sites, irrigation may present a solution for stimulating cork growth and thereby increasing production. This study presents an initial approach to characterizing cork grown in a forest stand associated with a specific water regime, by comparing cork growth on two plots—irrigated and a traditional rainfed—over an initial five-year period. Samples of cork tissue were analysed and several parameters were set: cell area, diameter, cell-wall thickness, number of cells, porosity, growth, and density. Irrigation plot samples showed on average: 25.83 ± 3.74 mm thickness, 5.17 ± 1.49 mm cork-ring width, 0.149 ± 0.041 g.cm−3 density, 13 ± 3.4% porosity coefficient in the tangential plane, 407.58 ± 268.22 µm2 cell area in the tangential plane and 887.80 ± 449.14 µm2 in the transverse plane, a total number of cells of 1232 ± 147 per mm2, and 1.03 ± 0.30 µm cell-wall thickness; whereas traditional rainfed plot samples presented: 21.33 ± 5.48 mm thickness, 3.08 ± 1.44 mm cork-ring width, 0.167 ± 0.068 g.cm−3 density, 10 ± 3.5% porosity coefficient in the tangential plane, 304.31 ± 205.83 µm2 cell area in the tangential plane and 752.45 ± 398.94 µm2 in the transverse plane, a total number of cells of 1481 ± 153 per mm2, and 1.204 ± 0.327 µm cell-wall thickness. As regards irrigation, two parameters, ring width and porosity coefficient, proved to be statistically significant, in contrast to density. [ABSTRACT FROM AUTHOR]

This study aims to investigate the optimal conditions for the elimination of albendazole (veterinary drug) by adsorption on activated carbon, prepared from a plant waste (pericarp of cork oak acorns). This low cost adsorbent was characterized by determining the Brunauer–Emmett–Teller surface area, morphology by using scanning electron microscope and surface chemical properties with Fourier transformed infrared spectroscopy. The pH of solution does not highly affect the adsorption of albendazole, a neutral environment (6.0–7.5) was more favorable. Responses surface methodology, namely Doehlert design was applied to model and optimize the adsorption process. The studied parameters are the pollutant concentration, activated carbon dose and temperature. Two responses were considered, albendazole elimination yield and adsorption capacity. The maximum elimination yield and adsorption capacity were 99.97% and 137.2 mg g−1, respectively. Analysis of variances and Mallows statistic criteria were applied to validate both predictive regression models. Multi-objective methodology using desirability approach was utilized to determine the optimal conditions, which are 50 mg L −1 of pollutant concentration; 1.6 g L −1 of adsorbent dose and 20 °C of temperature, corresponding to elimination yield of 88.8% and adsorption capacity of 82.0 mg g−1. The albendazole adsorption followed pseudo-second order kinetics. All isotherm models applied, namely, Freundlich, Langmuir, Temkin and Dubinin–Radushkevich fitted the experimental data with regression coefficient exceeding 0.930. The albendazole adsorption on the activated carbon was thermodynamically favorable. The application of Boyd's model showed that the intraparticle diffusion was not the rate limiting step, and the adsorption process may involve several mechanisms. [ABSTRACT FROM AUTHOR]

Aims: We studied the regeneration dynamics of woodlands and abandoned old fields in a landscape dominated by Quercus suber in its lower limits of rainfall and temperature. Two hypotheses were established: (1) regeneration of Quercus species is strongly favored by the presence of tree cover; and (2) growth of Q. suber is driven by the climatic variables that represent the lower ecological limit of its leading distribution edge. Methods: We selected woodlands and old fields with and without tree remnants (n = 3 per type), and analyzed stand structure, soil parameters and tree growth. Results: Succession was arrested in old fields without tree remnants. By contrast, remnant trees were accelerators of forest recovery in old fields. Tree cover played a fundamental role in Quercus recruitment throughout seed dispersal and facilitation that mitigate the effects of summer drought on seedlings. Also, tree cover improved soil parameters (e.g., organic matter) that are important factors for understanding differences in regeneration. Winter/spring precipitation exerted a positive effect on tree growth, as well as temperatures during winter/spring and September. Conclusions: Regeneration dynamics are modeled by the density of tree cover in the cold and dry edge of the distribution area of Q. suber where Q. ilex is increasing in abundance. Although temperature has a positive effect on the tree growth of Q. suber, when demographic processes are considered, decreases in water availability likely play a critical role in Q. ilex recruitment. This in turn changes dominance hierarchies, especially in abandoned areas with little or no tree cover. [ABSTRACT FROM AUTHOR]

Cork is a renewable resource mainly produced in Mediterranean countries thanks to sustainable management of cork oak (Quercus suber) stands. The infection caused by the ascomycete fungus Diplodia corticola promotes the occurrence of cankers that reduce cork regeneration devaluating the stands. In this article, we tested the hypothesis that the trees are susceptible to the fungus during a limited period of time after debarking. Five mature cork oaks were subjected to eight reiterative inoculations of D. corticola (from the day of debarking to 35 days after) in an experimental plot located in Catalonia (North-Eastern Spain). The time until first symptom appearance as well as the severity of necrosis were assessed for each inoculation treatment. A generalized linear mixed model was fitted showing that the time of symptoms appearance varied among the assayed times of inoculation. In contrast to the foresters-assumed idea of high susceptibility immediately after debarking, earlier inoculations were neither related to higher severity nor to earlier occurrence of canker. This study represents the first approach to this etiological issue in cork oak canker pathosystem. [ABSTRACT FROM AUTHOR]

The annual growth and the thickness of cork are known to be highly variable between trees located in the same geographical location. Researching how climate variables affect different trees within the same site is a step forward for the management of cork production since current knowledge focusses only on the average tree response. Quantile regression methodology was applied for the first time to a large data set containing measurements of cork growth, sampled in 35 stands across the cork oak distribution area in Portugal. This methodology proved to be useful for testing the hypothesis raised: does climate affect differently the annual cork growth, and ultimately cork thickness of individual trees located in the same stand? Estimating the amount of cork produced by one stand that has the required thickness for the production of natural cork stoppers is essential to support cork oak management. However, no model, before this work, had been developed to provide managers with this information. A downward parabolic relationship between annual cork growth and annual precipitation was determined for all quantiles, with optimum annual average precipitation value ranging from 1103 to 1007 mm. April to August monthly temperatures, spring average temperature or summer average temperature, showed a negative relationship with annual cork growth, in particular for lower quantiles. Maximum annual temperature was shown to negatively affect annual cork thickness, in particular for the trees under the 6th quantile. The ratio between annual precipitation and average temperature, that define the Lang index (LI), showed a downward parabolic relationship with annual cork growth. Best cork growth conditions are found for Lang index values around 60, corresponding for the transition between semi-arid climate and humid climate. The application of the final model developed for estimating cork thickness of an eight years' cork growth period allowed the prediction and mapping of the percentage of cork suitable for natural cork stopper production. It showed that higher values are expected in the Southern and Central coastal regions and along the Tagus River basin. The Northern coastal and mountain regions, characterised by Lang index values higher to 60 (humid climates), present lower estimated values for the percentage of cork suitable for natural cork stopper production. The estimated values are expected to be reduced under climate change scenarios in the Southern and Central coastal regions. [ABSTRACT FROM AUTHOR]

In Mediterranean forests, anthropogenic disturbances received little interest in regards to their shrub layer induced enlargement. We studied in the cork oak forest of Beni Métir and in undisturbed and disturbed sites, the relative contribution of the tree (LT, DLT) and shrub (LS, DLS) layers to litter fall, litter decomposition, and nutrients dynamic. Our results showed that disturbance significantly (p < 0.001) reduced (−43%) total litter fall in DS in comparison with S (583 g m−2 year−1); the increased (+ 54%) shrub layer contribution to site litter fall did not counterbalance the decreased input by the tree layer. Leaf litter decomposition was negatively affected (p < 0.001) by disturbance, the remaining mass value being after 2 years, approximately 14 and 33%, respectively, for S and DS. This resulted into a gain of above ground soil organic matter 1.3 higher in DS than it was in S whereas the shrub layer contribution to litter fall increased by 50%. The prevailing driver of decomposition was very probably not related to litter quality but rather site-dependent. Indeed, layers of the same site shared the same remaining mass in spite of significant differences (p < 0.05) in initial content of minerals (N, Ca, and Mn) implicated in biological decomposition. In the disturbed site, the nutrient input by the shrub layer increased by more than double, but its low nutrient quality drastically impaired litter decomposition and mineral return at the site level. In conclusion, this study highlighted the importance of shrub layer which must be taken into account when considering any disturbance assessment and management of Mediterranean forests. [ABSTRACT FROM AUTHOR]

In this work, we propose a mathematical model to determine the potential propagation areas of the Mediterranean Quercus disease commonly referred to as "seca" (Tuser and Sánchez 2004) in specific areas of Extremadura. Although it is a syndrome of complex etiology caused by the action of the different biotic (insects and fungi) and abiotic factors (temperature, orography, soil, etc.), numerous studies suggest that the soil-borne pathogen cinnamomi represents the main responsible for the decay of the holm and cork oak. However, very little is known about the Phytophthora epidemic distribution patterns and its geographical dependence on other factors that favor its spread. With the aim to clarify this question, in this paper, we will use optimal computational geometry algorithms based on proximity diagrams that allow us to design a pathogen transmission map and to determine its correlation with different causing agents, specially with the presence of standing water or drainage lines water. [ABSTRACT FROM AUTHOR]

Rhizosphere microbiome is one of the main sources of plant protection against drought. Beneficial symbiotic microorganisms, such as ectomycorrhizal fungi (ECMF) and mycorrhiza helper bacteria (MHB), interact with each other for increasing or maintaining host plant fitness. This mutual support benefits all three partners and comprises a natural system for drought acclimation in plants. Cork oak (Quercus suber L.) tolerance to drought scenarios is widely known, but adaptation to climate changes has been a challenge for forest sustainability protection. In this work, ECMF and MHB communities from cork oak forests were cross-linked and correlated with climates. Cenococcum, Russula and Tuber were the most abundant ECMF capable of interacting with MHB (ECMF~MHB) genera in cork oak stands, while Bacillus, Burkholderia and Streptomyces were the most conspicuous MHB. Integrating all microbial data, two consortia Lactarius/Bacillaceae and Russula/Burkholderaceae have singled out but revealed a negative interaction with each other. Russula/Burkholderaceae might have an important role for cork oak forest sustainability in arid environments, which will be complemented by the lower drought adaptation of competitive Lactarius/Bacillaceae. These microbial consortia could play an essential role on cork oak forest resilience to upcoming climatic changes. [ABSTRACT FROM AUTHOR]

An increase in tree mortality rates as a consequence of biotic disturbances has been detected worldwide. Biotic disturbances in forests might cause significant impacts at ecosystem-level, with strong effects on soil biological activity and organic matter transformation. However, very few empirical studies have explored to date the consequences of biotic disturbances for soil microbial communities and C and N cycles. Here, we assessed the effects of Quercus suber dieback, caused by the exotic root pathogen Phytophthora cinnamomi, on the soil microbial community and key components of the C and N cycle. We used a spatially explicit neighborhood approach to analyze the effects of Q. suber trees with different health status and non-declining coexistent species on soil variables. The study was replicated in the two main Q. suber forest types of the region (closed forests and open woodlands) with contrasting soil texture characteristics. Pathogen-induced tree dieback did not affect microbial functional diversity or biomass, but translated into lower soil microbial respiration. Tree mortality induced changes in several variables of the C and N cycle, but the sign and magnitude of these effects varied depending on the local characteristics of soil texture. Coexistent species differed strongly from Q. suber in their effects on the C and N cycle. Overall, our results show that tree dieback due to invasive pathogens translates into complex short- and long-term effects on different components of the C and N cycles, despite no effects on microbial functional diversity and biomass. [ABSTRACT FROM AUTHOR]

Cork oak decline and mortality are increasingly prevalent in the Mediterranean basin. This require particular attention due to the great economic value of this plant species. Biscogniauxia mediterranea is one of the most common pathogens highly associated to cork oak decline. However, documentation on its incidence is still scarce, especially in Tunisia. In this context, our research aimed at detecting its presence in Tunisian natural cork oak forests and assessing factors influencing its occurrence. Investigations were carried out in six forests in northwestern Tunisia. Dendrometric parameters of trees, ecological factors (rainfall, temperature, and altitude), and the presence of B. mediterranea as pathogen were determined. The endophytic presence of this fungus was also established. It was detected in all investigated forests, with significantly different frequencies, and was reported to be related to the dendrometric structure of the cork oak trees. On the other hand, the presence of B. mediterranea as pathogen was only detected in Ain Beya and Ain Sarouia forests. It was very limited with 4% of trees per site showing the disease signs. In conclusion, measures to prevent the dispersal of B. mediterranea throughout other cork oak forests shall be implemented in order to conserve such valuable forest resources. [ABSTRACT FROM AUTHOR]

While the effects of seed size on survival and early seedling growth have been demonstrated in Quercus spp., there is a knowledge gap regarding these effects under water limiting conditions. To address this need, we studied cork oak (Quercus suber L.) seedling development among treatments including three acorn classes (small: < 4 g, intermediate: 4–6 g), and large: ≥ 6 g) and two water regimes (well-watered versus water stressed). The following hypotheses were proposed: the reserve effect (larger seeds retain a larger proportion of reserves after germinating), the metabolic effect (seedlings from larger seeds have slower relative growth rates), the seedling-size effect (larger seeds produce larger seedlings), and that plant tolerance to water stress increases with increasing seed size. Acorn size had no effect on duration and rate of acorn germination nor on seedling survival, but it significantly affected almost all growth parameters, excepting the number of growth unit and leaves and leaf area. Seedlings coming from large acorns always showed the highest values for the affected growth parameters, followed by those coming from acorns of intermediate size; seedlings coming from small acorns always exhibited the lowest values. Water stress significantly affected survival rate (88.2% for well-watered seedlings versus 64.7% for water stressed seedlings) and biomass of fine roots and stems, but independently of acorn size. Our results are in line with both hypothesizes of the reserve effect and seedling-size effect, but not for the metabolic effect nor the plant tolerance to water stress increases with increasing seed size hypotheses. In general, our results show that large acorns had no advantage in survival or seedling growth under water stress comparatively to intermediate or small acorns, at least under the conditions of our experiment. [ABSTRACT FROM AUTHOR]

This study aims to analyse the availability and variability of soil moisture and its evolution considering climate change (CC) scenarios in a typical Mediterranean forest of cork oak (Quercus suber L.). The investigation was conducted in 3 forest stations at north-western Tunisia. Gravimetry and time domain reflectometry (TDR) were used to assess soil moisture. Biljou (BILan JOUrnalier), a daily water balance model, was applied to simulate the relative extractable water variation in 2009 as a reference simulation. Alike, other simulations of CC were performed using hypothetic meteorological and/or silvicultural data. The top-layer soil humidity fluctuates between 5 and 25% depending on time and stations. This oscillation interval narrows for the soils’ surface layer (7%). The forest surface conserves a soil moisture memory varying on a small spatial scale but stable over time. The deep layers of the three stations have the same way due to the attenuation of the biological and atmospheric influence. 2009’s reference simulation makes it possible to distinguish a low and slight period of stress easy to overcome (9 days with intensity 0.4). Soil drying severity, duration, and earliness will vary from one scenario to another. The number of days and the intensity of stress are high for all scenarios (64 to 166 days with intensity from 12 to 42.2). The most severe and persistent period of stress will be when the rain will be nil during summer and especially if summer period extends. CC impacts will be amplified when climatic and silvicultural scenarios are combined. [ABSTRACT FROM AUTHOR]

The thickness of bark (cork) is of utmost importance for its industrial processing and, therefore, for the sustainable management of cork oak (Quercus suber L.) woodlands. Cork thickness has been reported to decrease from the stem base upwards but, to our knowledge, prediction models have not yet been presented. This study intended to develop reliable models to predict stem profiles of cork thickness. We addressed the relationship between bark thickness and stem height by measuring stem diameters and cork thickness at various stem heights in 76 trees. Through a repeated measure ANOVA, we selected the bark thickness response variables, cork-ring width and cork thickness. A mixed-effect modelling approach was used to fit linear bark thickness curves with stem height. Our results showed that the equations that performed better for cork thickness were functions of the stem relative height and cross-sectional cork area increment. The decreasing trend upwards the stem might lead to underestimation of cork thickness at the base, more than overestimate it at upper stem parts, in relation to the values at breast height, which are generally used to estimate the thickness of the whole cork plank. Furthermore, cork thickness curves were tree size-related, with larger trees exhibiting a steeper reduction in cork thickness upwards the stem. [ABSTRACT FROM AUTHOR]

Climate change induces in the Mediterranean region more frequent and extreme events, namely, heat waves and droughts, disturbing forest species and affecting their productivity and product quality. The cork oak (Quercus suber) is present along the western Mediterranean basin and its outer bark (cork) is sustainably collected and used for several products, mainly wine bottle stoppers. Since most cork properties arise from its chemical composition, this research studies the effect of drought on cork chemical composition (suberin, lignin, polysaccharides and extractives) and on polysaccharide and suberin monomeric composition. Three sets of cork samples, from the same site, were examined: in one set the cork grew without drought; in another two drought events occurred during cork growth and in the third one drought event happened. The results show that, in general, drought does not affect the proportion of the main components of cork, the monomers of suberin or of polysaccharides, with few exceptions e.g. drought increased ethanol extractives and xylose in polysaccharides and decreased arabinose in polysaccharides. The variability associated to the tree is much more relevant than the effect of drought conditions and affects all the parameters analyzed. Therefore, our research suggests that the tree genetic information, or its expression, plays a much more important role on the chemical composition of cork than the drought conditions occurring during cork growth. In practical terms, the potential increased occurrence of droughts arising from climatic changes will not compromise the performance of cork as a sealant for wine bottles. [ABSTRACT FROM AUTHOR]

Scheduling the first thinning in young cork oak stands is an important decision in management that is usually subjectively defined by each manager. An analysis of competition in cork oak plantations is extremely relevant as a support for this important decision. This study aimed to understand the relationship between stand characteristics and tree growth efficiency, and subsequently help identify the presence or absence of an inter-tree competition pattern in cork oak stands that were never debarked. The inter-tree competition was assessed by looking to several stand characteristics: (1) comparison with the self-thinning line; (2) stand density measures, such as stand spacing coefficient and relative spacing; (3) stand structure measures evaluated through the skewness and variability; and (4) tree relative growth rate pattern over tree size. Data used for this analysis were gathered from permanent plots that were established in even-aged stands located across the cork oak distribution area in Portugal. The study shows that the most common stand densities on young cork oak plantations might not lead to serious inter-tree competition before the first cork extraction. This information is relevant to support the potential timing and severity of the first thinning in order to retain more trees until the second cork extraction when cork quality can be taken into account in the selection of the trees to be removed. [ABSTRACT FROM AUTHOR]

Drought has been assumed as a predisposing factor in the decline caused by Phytophthora cinnamomi on Mediterranean Quercus forests, enhancing cork oak susceptibility to the root infection. However, P. cinnamomi outbreaks appear associated to waterlogged soils, with infections being particularly successful when soil moisture content fluctuates from flooding to water deficiency. We obtained cork oak seedlings potentially predisposed to Phytophthora disease by exposing them to a short (3 weeks) or a long (6 weeks) drought. These seedlings subjected to drought, together with well-watered seedlings, were exposed to two different soil concentrations of P. cinnamomi inoculum (chlamydospores) and submitted to high soil humidity for 4 weeks. Values of root necrosis were significantly higher in inoculated oak seedlings compared to non-inoculated control seedlings, but no significant differences were observed depending on previous drought treatments. Consequently, drought cannot be considered as a predisposing factor required for Phytophthora root disease development in cork oaks; although the adverse effects of both factors (drought and Phytophthora root infections) likely have synergistic consequences in the decline and death of affected oaks. [ABSTRACT FROM AUTHOR]

Portuguese forest sustainability is currently threatened by forecasted climate changes and inappropriate management practices. Specifically, large cork oak woodland areas (montados) are subjected to soil degradation and tree recruitment impeachment. A study was developed to compare soil properties in cork oak woodlands with improved pastures (IP) grazed by cattle and natural understorey management (NU) without grazing. The IP system did not lead to soil organic C concentration increase, soil organic C stock being 0.7 kg m−2 lower in the upper 30 cm soil layer, compared to the NU system. Under the IP management, soil N content was 39.7 g m−2 higher up to 30 cm depth, and N mineralization potential was increased by 50% in the 10 cm top soil layer. Soil bulk density and C mineralization potential were similar in both systems. Sowing legume-rich pastures can result in an immediate soil quality improvement, especially regarding N availability, although grazing may hamper tree recruitment. Managing the natural understorey appears suitable for soil organic C maintenance, and also allows tree recruitment, while soil N availability limitation could be overcome by fertilizer applications. [ABSTRACT FROM AUTHOR]

In Spain, natural and managed cork oak woodlands are severely affected by decline caused by the root rot oomycetes Phytophthora cinnamomi and Pythium spiculum. The need for environmental-friendly disease management makes the use of resistance inducers a suitable option. As the use of phosphite is prohibited in Spain, trunk injections of fosetyl-aluminium were tested in a seminatural cork oak woodland (dehesa). Sixty cork oaks in three different defoliation classes (asymptomatic, slight, and moderate defoliation) were selected for fosetyl- aluminium or control (water) trunk injections, and periodically checked for defoliation and presence of both pathogens in roots and rhizosphere soil. Three years after treatments, fosetyl-aluminium injection significantly decreased defoliation in treated cork oaks in comparison with water-injected controls, regardless of the initial defoliation class considered. Changes in inoculum density in the rhizosphere or presence of the two pathogens in roots were not significantly dependent on treatment. However, a trend to a lower presence of pathogens in roots of treated oaks was observed with increasing soil inoculum densities. Fosetyl-aluminium, a phosphonate fungicide registered in the European Union, was experimentally proved to protect cork oaks against root rot caused by P. cinnamomi and Py. spiculum, even exhibiting a therapeutic effect on preexisting infections. This effective measure can therefore be used to fight against this highly destructive disease in seminatural woodlands and in protected natural ecosystems. [ABSTRACT FROM AUTHOR]

Key message: The fasciclin-like arabinogalactan proteins organization into four groups is conserved and may be related to specific roles in developmental processes across angiosperms. Fasciclin-like arabinogalactan proteins (FLAs) are a subclass of arabinogalactan proteins (AGPs), which contain fasciclin-like domains in addition to typical AGP domains. FLAs are present across all embryophytes, and despite their low overall sequence similarity, conserved regions that define the fasciclin functional domain (FAS) have been identified, suggesting that the cell adhesion property is also conserved. FLAs in Arabidopsis have been organized into four subgroups according to the number and distribution of functional domains. Recent studies associated FLAs with cell wall-related processes where domain organization seemed to be related to functional roles. In Arabidopsis, FLAs containing a single FAS domain were found to be important for the integrity and elasticity of the plant cell wall matrix, and FLAs with two FAS domains and two AGP domains were found to be involved in maintaining proper cell expansion under salt stress conditions. The main purpose of the present work was to elucidate the expression pattern of selected FLA genes during embryo and seed development using RT-qPCR. AtFLA8 and AtFLA10, two Arabidopsis genes that stood out in previous microarray studies of embryo development, were further examined using promoter-driven gene reporter analyses. We also studied the expression of cork oak FLA genes and found that their expression partially parallels the expression patterns of the putative AtFLA orthologs. We propose that the functional organization of FLAs is conserved and may be related to fundamental aspects of embryogenesis and seed development across angiosperms. Phylogenetic studies were performed, and we show that the same basic four-subgroup organization described for Arabidopsis FLA gene classification is valid for most Arabidopsis FLA orthologs of several plant species, namely poplar, corn and cork oak. [ABSTRACT FROM AUTHOR]

Mediterranean agroforestry systems, which integrate livestock and/or forage crops might benefit from legume establishment, as a key tool to increase grassland productivity and sustainability. This study is aimed at evaluating the forage performances and N fixation ability of different legume based swards affected by light intensity in a Mediterranean silvopastoral system, where plots in open areas with full sunlight and under tree canopy were identified. Beneath cork oak cover with a partial shade (70% of light interception), aboveground dry matter yield represented 41, 45, 46 and 52% compared to the corresponding values under full sunlight of legume based swards under comparison, namely unsown semi natural pasture, CNR mixture, bladder clover pure sward and Fertiprado mixture, respectively. Crude protein content significantly increased (up to 57%) in partial shade, whereas Neutral Detergent Fiber was not significantly affected by light intensity. Results evidenced that the rates on N derived from the atmosphere by the understory legumes, estimated by 15N isotopic dilution method and using barley as a non-fixing reference species, were about half than the corresponding values obtained under full sunlight. Additionally, partial shade led to longer shoots and wider plant leaf area in several legume species, whereas leaf chlorophyll content were unaffected by light intensity. Photosystem efficiency ratio was also affected by light intensity. Our research quantified clear reductions in N derived from atmosphere rates caused by light reduction under partial shade. Concurrently, results highlight relevant variations in legume plant biomass yield and traits. [ABSTRACT FROM AUTHOR]