•Remote sensing indexes and tree-rings/wood anatomy data were compared.•High variability among sites and tree species in their responses to drought.•Ash seem to perform better then oak in terms of ...growth under drought.•Relevant effect for forest management and ecosystem services.
Drought reduces canopy cover, productivity and tree growth in forests. However, there is still little knowledge on how drought affects coupling between canopy greenness assessed by remote sensing and hydraulic conductivity detected by wood anatomy. This combination could improve the understanding of forest response to climate change. Thus, we investigated the impacts of a hot drought, which occurred in summer 2017, on radial growth, earlywood hydraulic diameter (Dh), a proxy of conductivity, and several remote-sensing indices in mixed Mediterranean hardwood forests (Quercus pubescens Willd. – Fraxinus ornus L.). In general, growth showed a higher coherence among trees and a higher responsiveness to climate. Growth decreased during the drought year, particularly for Q. pubescens, which showed high defoliation and dieback intensity. Both species showed a decline of Dh in 2018 after the drought and subsequent warm winter conditions. We found positive relationships between Dh and remote-sensing data for Q. pubescens in some of these vulnerable sites, where (i) growth was constrained by dry spring-summer conditions and (ii) Dh and growth covaried. These findings indicate a high variability among sites and tree species in their responses to drought considering earlywood anatomy, growth canopy cover and water content. However, some common patterns emerge such as links between potential hydraulic conductivity (Dh), tree cover and Dh-growth covariation in the most impacted sites. Further, F. ornus seem to perform better in terms of growth under drought conditions, showing less mortality and dieback than Q. pubescens. Future studies could explore how water transport and changes in canopy cover respond to dry and warm conditions and if that covariation indicates vulnerability to drought.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Soil sealing is one of the most pervasive forms of soil degradation that follows urbanization and, despite innovative pavements (i.e. pervious) are being installed in urban areas to mitigate it, ...there is little research on the effects of pervious pavements on soil water and carbon cycle and on the physiology of urban trees. The aim of this 4-year experiment was to assess the effects of three pavements, differing in permeability to water and gases, on some soil physical parameters, and on growth and physiology of newly planted Celtis australis and Fraxinus ornus. Treatments were: 1) impermeable pavement (asphalt on concrete sub-base); 2) permeable pavement (pavers on crushed rock sub-base); 3) porous design (porous pavement on crushed rock sub-base); 4) control (unpaved soil, kept free of weed by chemical control). Soil (temperature, moisture, oxygen content and CO2 efflux) and plant (above- and below-ground growth, leaf gas exchange, chlorophyll fluorescence, water relations) parameters were measured.
All types of pavements altered the water cycle compared to unpaved soil plots, but this disturbance was less intense in porous pavements than in other soil cover types. Porous pavements allowed both higher infiltration and evaporation of water than both pavers and asphalt. Reduction of evaporative cooling from soil paved with permeable and impermeable pavements contributed to significant soil warming: at 20cm depth, soils under concrete pavers and asphalt were 4 and 5°C warmer than soil covered by porous pavements and unpaved soils, respectively. Thus, enhancing evaporation from paved soil by the use of porous pavements may contribute to mitigating urban heat islands. CO2 greatly accumulated under impermeable and permeable pavements, but not under porous pavements, which showed CO2 efflux rates similar to control. Soil oxygen slightly decreased only beneath asphalt.
Growth of newly planted C. australis and F. ornus was little affected by pavement type. Tree transpiration rapidly depleted soil moisture compared to the not-planted scenario, but soil moisture did not fall below wilting point (particularly in the deeper soil layers, i.e. 40–50cm) in any treatment. While C. australis showed similar leaf gas exchange and water relations in all treatments, F. ornus showed a depression in CO2 assimilation and slight signs of stress of the photosynthetic apparatus when planted in soil covered with impermeable pavement.
The effects of soil cover with different materials on tree growth and physiology were little, because newly planted trees have most of their roots still confined in the unpaved planting pit. Still, the reduction of soil sealing around the planting pit triggered the establishment of sensitive species such as ash. Further research is needed to assess the effects of different pavement types on established, larger trees.
•Soil sealing depresses water and carbon exchange between soil and the atmosphere.•As a consequence of reduced evaporation, warming occurs in sealed soils.•Disturbance to element cycling can be mitigated by the use of porous pavements.•Tree responses to pavements is species-specific, but generally little for establishing trees.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
Summary
Woody plants display some photosynthetic activity in stems, but the biological role of stem photosynthesis and the specific contributions of bark and wood to carbon uptake and oxygen ...evolution remain poorly understood.
We aimed to elucidate the functional characteristics of chloroplasts in stems of different ages in Fraxinus ornus. Our investigation employed diverse experimental approaches, including microsensor technology to assess oxygen production rates in whole stem, bark, and wood separately. Additionally, we utilized fluorescence lifetime imaging microscopy (FLIM) to characterize the relative abundance of photosystems I and II (PSI : PSII chlorophyll ratio) in bark and wood.
Our findings revealed light‐induced increases in O2 production in whole stem, bark, and wood. We present the radial profile of O2 production in F. ornus stems, demonstrating the capability of stem chloroplasts to perform light‐dependent electron transport. Younger stems exhibited higher light‐induced O2 production and dark respiration rates than older ones.
While bark emerged as the primary contributor to net O2 production under light conditions, our data underscored that wood chloroplasts are also photosynthetically active. The FLIM analysis unveiled a lower PSI abundance in wood than in bark, suggesting stem chloroplasts are not only active but also acclimate to the spectral composition of light reaching inner compartments.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Previous favorable climate conditions stimulate tree growth making some forests more vulnerable to hotter droughts. This so-called structural overshoot may contribute to forest dieback, but there is ...little evidence on its relative importance depending on site conditions and tree species because of limited field data. Here, we analyzed remote sensing (NDVI) and tree-ring width data to evaluate the impacts of the 2017 drought on canopy cover and growth in mixed Mediterranean forests (Fraxinus ornus, Quercus pubescens, Acer monspessulanum, Pinus pinaster) located in southern Italy. Legacy effects were assessed by calculating differences between observed and predicted basal area increment (BAI). Overall, the growth response of the study stands to the 2017 drought was contingent on site conditions and species characteristics. Most sites presented BAI and canopy cover reductions during the drought. Growth decline was followed by a quick recovery and positive legacy effects, particularly in the case of F. ornus. However, we found negative drought legacies in some species (e.g., Q. pubescens, A. monspessulanum) and sites. In those sites showing negative legacies, high growth rates prior to drought in response to previous wet winter-spring conditions may have predisposed trees to drought damage. Vice versa, the positive drought legacy found in some F. ornus site was linked to post-drought growth release due to Q. pubescens dieback and mortality. Therefore, we found evidences of structural drought overshoot, but it was restricted to specific sites and species. Our findings highlight the importance of considering site settings such as stand composition, pre-drought conditions and different tree species when studying structural overshoot. Droughts contribute to modify the composition and dynamics in mixed forests.
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•We have little knowledge on drought impacts on mixed Mediterranean forests.•We analyzed Mediterranean mixed broadleaves forests affected by the 2017 drought.•Most study stands showed a rapid growth recovery after drought.•In some sites, stand structural overshoot predisposed to drought damage.•Overshoot drought responses depend on historical pre-drought conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
•High pine cover favoured late successional resprouter seedling survival.•Seedlings growth response to pine cover depended on their functional strategy.•Pine-seedling interactions were noticeable ...after 2 years, intensifying with time.•We need long-term monitoring to assess plant interactions and restoration success.
Monospecific pine forests are widespread due to extensive afforestation efforts and natural colonization of abandoned croplands in the Mediterranean Basin. It was originally thought that pines would facilitate the natural colonization of native late-successional resprouter species (e.g., hardwoods), but these species can be compromised if competition with pines outweighs their facilitative effect on these hardwood species. Managing the density or canopy cover of these widespread pine forests can potentially provide some “optimum” balance between facilitation and competition to maximize success in the introduction of late successional species while maintaining a tree stratum. We tested the response (survival and growth across 10 years) of six resprouter species covering a wide range of plant functional strategies, from drought-tolerant sclerophyllous shrubs and trees to malacophyllous drought-sensitive trees, across an experimental gradient of Aleppo pine canopy cover. Seedling performance varied according to the functional strategy, pine cover and time. High pine cover generally enhanced seedling survival, whereas moderate pine cover generally enhanced seedling growth, although this response was modulated by the functional strategy of the seedling species. Interactions between pines and seedlings were only detectable 2–3 years after plantation, increasing in intensity with time. The latter highlights the need of medium to long-term studies to evaluate plant-plant interactions in these water-limited environments with slow successional trajectories. Our results could be attributed to the shade tolerance of most of the introduced trees, combined with their low tolerance to the combination of high sunlight radiation and drought. We found an optimal pine cover of ca. 50% (equivalent to 300–400 trees/ha) in which both survival and growth of late successional species can be maximized, which help to select best locations for more efficient reforestation programs and set a threshold value to decide whether or not to perform tree thinning to enhance ecosystem diversity and, subsequently, resilience.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
In this work, the total content of phenolics, flavonoids, and phenolic acids in the leaves and bark extracts of Fraxinus ornus L. and Fraxinus excelsior L. was determined. In addition, the ...identification and quantification of phenolic acids was performed using the HPLC-DAD technique. Samples were tested for antioxidant activity using the ABTS and DPPH methods. Eight extract samples were prepared by Soxhlet and ultrasound extraction using 70 % ethanol as solvent. The content of phenolic compounds ranged from 7.59 for F. ornus to 88.93 mg GAE/g for F. excelsior in the bark extracts obtained by Soxhlet extraction. The highest content of total flavonoids in F. ornus and F. excelsior was found in the leaves extracts obtained by ultrasound extraction, which was 5.68 and 1.74 mg GAE/g extract, respectively. The results also showed that the highest content of total phenolic acids was found in F. ornus (105.33 mg CAE/g) and F. excelsior (97.97 mg CAE/g) in the bark extract obtained by Soxhlet extraction. The highest content of gallic acid (112.96 ± 1.32 mg g –1 extracts) and chlorogenic acid (246.94 ± 0.82 mg g –1 extracts) was found in the F. ornus bark extract obtained by ultrasound extraction. As for antioxidant activity, the bark extract obtained by Soxhlet extraction of F. ornus showed the best antioxidant activity by ABTS method with IC 50 value of 0.062 mg ml –1 . The results of the DPPH method show that the leaves extract obtained by Soxhlet extraction had the best antioxidant activity for the F. ornus sample, with an IC 50 value of 0.23 mg ml –1 .
U ovom radu određen je ukupni sadržaj fenola, flavonoida i fenolnih kiselina u ekstraktima lišća i kore Fraxinus ornus L. i Fraxinus excelsior L. Dodatno, identifikacija i kvantifikacija fenolnih kiselina provedena je pomoću tehnike HPLC-DAD. Uzorci su ispitani na antioksidativno djelovanje metodama ABTS i DPPH. Osam uzoraka ekstrakta, pripremljeno je Soxhlet i ultrazvučnom ekstrakcijom uporabom 70 % etanola kao otapala. Sadržaj fenolnih spojeva kretao se od 7,59 za F. ornus do 88,93 mg GAE/g za F. excelsior u ekstraktima kore dobivenim Soxhlet ekstrakcijom. Najveći sadržaj ukupnih flavonoida u uzorcima F. ornus i F. excelsior određen je u ekstraktima listova dobivenih ultrazvučnom ekstrakcijom i iznosio je 5,68 odnosno 1,74 mg GAE/g ekstrakta. Rezultati su također pokazali da je najveći sadržaj ukupnih fenolnih kiselina utvrđen u F. ornus (105,33 mg CAE/g) i F. excelsior (97,97 mg CAE/g) u ekstraktu kore dobivenom Soxhlet ekstrakcijom. Najveći sadržaj galne kiseline (112,96 ± 1,32 mg g –1 ekstrakata) i klorogenske kiseline (246,94 ± 0,82 mg g –1 ekstrakata) detektiran je u ekstraktu kore F. ornus dobivenom ultrazvučnom ekstrakcijom. Što se tiče antioksidativnog djelovanja, ekstrakt kore uzorka F. ornus dobiven Soxhlet ekstrakcijom pokazao je najbolje antioksidativno djelovanje metodom ABTS s IC 50 vrijednošću od 0,062 mg ml –1 . Rezultati metode DPPH pokazali su da je ekstrakt lišća dobiven Soxhlet ekstrakcijom imao najbolje antioksidativno djelovanje za uzorak F. ornus s IC 50 vrijednošću od 0,23 mg ml –1 .
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This study investigated the impact of different types of soil sealing on the communities of a group of beneficial plant symbionts, arbuscular mycorrhizal fungi (AMF), colonizing the roots of two ...shade trees, Celtis australis and Fraxinus ornus, frequently grown in urbanized sites. Such plants were grown in an experimental site, in northern Italy, established in November 2011 and subjected to four different pavement treatments: impermeable monolithic asphalt, permeable pavers, permeable concrete and unpaved soil. The diversity and composition of root AMF communities were assessed by PCR denaturating gradient gel electrophoresis of partial 18S rRNA gene, AMF taxa were identified by amplicon sequencing and mycorrhizal colonization was evaluated after root clearing and staining. For the first time, our molecular work revealed that impermeable pavements induced shifts in the composition of AMF communities associated to the roots of C. australis and F. ornus and impacted on the percentage of mycorrhizal root length. When the root-zone was covered with permeable pavements, a similar AMF community as that observed in the unpaved soil was detected, providing novel information to be utilised for reducing the disturbance caused by specific types of soil sealing on AMF symbionts, which play a key role in plant nutrition and health. A total of 45 AMF sequence types were detected, with Sclerocystis and Septoglomus as the most abundant phylotypes, accounting for 84% of the sequences. The predominance of Sclerocystis species in the roots of both tree species under impermeable pavements indicated their high and unforeseen tolerance towards harsh environmental conditions. Such species could be utilized as AMF inocula specifically selected for their proven resilience in paved sites, in order to exploit their ability to boost biogeochemical processes fundamental for energy fluxes and plant nutrition and health.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Early vat bacterial biofilms developed spontaneously through contact with whey have been characterized on seven wood types (Castanea sativa Miller, Cedrus libani, A. Rich., Prunus avium L., Fraxinus ...ornus L., Juglans regia L., Pinus nigra J.F. Arnold and Populus nigra L.). The present study aimed to evaluate the influence of these biofilms on the microbiological, chemical, physical and sensory characteristics of PDO Vastedda della valle del Belìce (VdB) cheese, processed traditionally from raw ewe's milk using wooden tools. To this purpose, the experimental cheeses after 15 d of refrigerated storage were examined. Lactic acid bacteria (LAB) populations dominated the microbial community of all samples. The species more frequently identified were Lactococcus lactis among starter LAB and Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus fermentum and Pediococcus pentosaceus among non starter LAB. Culture-independent analysis of microbiota diversity was performed by MiSeq Illumina that identified Streptococcus as major group followed by members of Enterobacteriaceae family, Lactococcus and Lactobacillus. Generally, the seven tree species did not negatively affect the physicochemical composition of VdB cheeses. Chestnut (both Sicilian and Calabrian) vats produced cheeses with significant lower hue angle (a*/b*) than other wood types. Among chemical parameters, significant variations were registered for aw, primary and secondary lipid oxidation state (significantly lower for the VdB cheeses produced with poplar wood), and volatile organic compounds (VOCs). The significant differences detected among the VOCs emitted from cheeses were not perceived by the panelists who recognized all cheeses from the different trials as similar. This study confirmed the suitability of cedar, cherry, ash, walnut, black pine and poplar as alternative woods to chestnut for the production of the wooden vats employed in cheese making for the Sicilian traditional dairy productions.
•The biofilms newly developed onto different wooden vats did not transfer pathogens•Lactic acid bacteria from biofilms dominated the fermenting microflora of cheeses•Illumina identified Streptococcus, Lactococcus and Lactobacillus as dominant LAB•The different wood types did not greatly affect physical parameters•Sensory analysis showed that all wood types generated comparable cheeses
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
The purpose of this publication is to review and analyze the main studies of Manna ash in Bulgaria in or-der to present summarized information and acquire an objective view of the possibilities for ...proper per-ception of the importance of this local tree species and its use in various aspects of science and practice in our country. The study covers the period from the second half of the 1940s, when the first specialized journals in the field of forest science were published, until 2022. The focus of the study is on publications related directly or indirectly to various aspects of research on manna ash.
The tracking of the chronology of forestry studies in Bulgaria shows trends towards a change in the perception of Manna ash as an inferior species and the search for its benefits for forestry practice, including rethinking its role from one of a weed species into an adjustable competitor, stimulating the regeneration of oaks and others indigenous species in plantations.
The role of phytocoenological studies, which in relation to the Manna ash communities, both in nat-ural and artificial forest plantations, with its participation have increased in recent years. With their help, it is possible to trace the stages of successions and fluctuations and behavior of Manna ash in xerothermic oak forests and austian pine crops - its ecological-coenotic strategy towards the main tree species.
The studies of Manna ash in Bulgaria in the field of special uses are close to their European ana-logues and in a number of cases overtake them with new data and discoveries, mostly in terms of bio-logically active products and antiallergic agents obtained from this plant species, among which we have world patents.
Increased frequency of tree mortality and forest decline due to anomalous drought events calls for the adoption of effective monitoring of tree water status over large spatial and temporal scales. We ...correlated field-measured and remotely sensed plant water status parameters, to test the possibility of monitoring the risk of drought-induced dehydration and hydraulic failure using satellite images calibrated on reliable physiological indicators of tree hydraulics. The study was conducted during summer 2019 in the Karst plateau (NE Italy) in a woodland dominated by Fraxinus ornus L.; Sentinel-2 images were acquired on a seasonal scale on the same dates when absolute water content (AbWC), relative water content (RWC), and minimum water potential (Ψmin) were measured in the field. Plant water status parameters were correlated with normalized difference vegetation index (NDVI and NDVI 8A), normalized difference water index (NDWI), and soil-adjusted vegetation index (SAVI). Significant Pearson and Spearman linear correlations (α < 0.05) emerged between all tree-level measured variables and NDWI, while for NDVI, NDVI 8A, and SAVI no correlation was found. Our results suggest the possibility of using the NDWI as a proxy of tree water content and water potential.
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