Pinus Halepensis Mill Research Articles

Greenhouse investigation on the phytoremediation potential of pioneer tree Pinus halepensis Mill. in abandoned mine site

Tailings and mine dumps are often pollutant sources that pose serious environmental threats to surrounding areas. The use of pioneer vascular plants to extract or stabilize metals is considered among the more effective mine tailing reclamation techniques. The study aimed at evaluating the phytoremediation potential of Pinus halepensis in abandoned mine-tailing (SW-Sardinia, Italy). Plant ability to tolerate high Zn, Pb, and Cd concentration and their accumulation in roots and aerial parts were assessed at greenhouse conditions. Experiments were performed on 45 seedlings planted in different substrates (mine-tailings, mine-tailings compost-amended, and reference) and on 15 seedlings grown spontaneously in the contaminated mine site investigated with their own substrates. The phytostabilization potential of plant was evaluated through biological accumulation and translocation indexes together with plant survival and biometric parameters. The outcomes showed the adaptability of P. halepensis to grow and survive in contaminated substrates. Compost addition did not improve plant survival and growth, however, it enhanced total carbon and nitrogen contents of soil, restricted metal bioavailability, and accumulation in plant aerial parts. These findings highlight that P. halepensis may be considered for phytostabilization given the great potential to limit Zn, Pb, and Cd toxicity in plant tissues by applying compost amendment in metal contaminated mine sites.

Physiological and phenological adjustments in water and carbon fluxes of Aleppo pine forests under contrasting climates in the Eastern Mediterranean.

The ability of plants to adjust to the adverse effects of climate change is important for their survival and for their contribution to the global carbon cycle. This is particularly true in the Mediterranean region, which is among the regions that are most vulnerable to climate change. Here, we carried out a 2-year comparative ecophysiological study of ecosystem function in two similar Eastern Mediterranean forests of the same tree species (Pinus halepensis Mill.) under mild (Sani, Greece) and extreme (Yatir, Israel) climatic conditions. The partial effects of key environmental variables, including radiation, vapor pressure deficit, air temperature and soil moisture (Rg, D, T and soil water content (SWC), respectively), on the ecosystems' CO2 and water vapor fluxes were estimated using generalized additive models (GAMs). The results showed a large adjustment between sites in the seasonal patterns of both carbon and water fluxes and in the time and duration of the optimal period (defined here as the time when fluxes were within 85% of the seasonal maximum). The GAM analysis indicated that the main factor influencing the seasonal patterns was SWC, while T and D had significant but milder effects. During the respective optimal periods, the two ecosystems showed strong similarities in the fluxes' responses to the measured environmental variables, indicating similarity in their underlying physiological characteristics. The results indicate that Aleppo pine forests have a strong phenotypic adjustment potential to cope with increasing environmental stresses. This, in turn, will help their survival and their continued contribution to the terrestrial carbon sink in the face of climate change in this region.

Testing transpiration rates of juvenile Aleppo pine trees using the heat ratio method under laboratory conditions

AbstractTree transpiration considerably contributes to evaporative fluxes to the atmosphere in terrestrial ecosystems. Accurate transpiration quantification provides relevant information about forest water use and may benefit adaptive forest management, especially in a global change context. Tree transpiration can be measured by several methods, and sap flow measurements are one of the most valued. However, species‐specific validations of these techniques are required to avoid undesirable bias. This is especially relevant in species with low transpiration rates where errors may be relevant, such as Aleppo pine trees (Pinus halepensis Mill.). Moreover, another significant source of uncertainty in sap flow measurements is probe misalignment. Hence, the aim of this study was to correlate transpiration rates estimated by sap flow probes using the heat ratio method (THRM) and load cells to independently monitor water transpiration in juvenile Aleppo pine trees. The corrections to improve transpiration measures, including misalignment correction, were applied to THRM results to test if the accuracy of results improved. These measurements were recorded in greenhouse under controlled conditions to implement different environmental conditions. The environmental variables that ruled the experiment, mainly vapour pressure deficit and soil water availability, spanned in a wide range of values. The results showed an accurate linear correspondence between TOBS and THRM for low and medium values, but moderate underestimations at high transpiration rates were observed. These underestimations were partly removed when applying probe misalignment correction. This study supports the notion that HRM offers accurate Aleppo pine transpiration estimations with low and medium values under a variety of abiotic conditions, which also has implications for HRM application in other isohydric species. The results also support the interest in the use of probe misalignment correction to estimate transpiration, mainly when high transpiration values are recorded. The results of this study can be considered as a preliminary approach for future research in order to improve the estimates of the transpiration rates of the Aleppo pine under the limiting conditions of the Mediterranean.

Cold pressed Pinus halepensis Mill. seed oil for potential health applications: Analgesic, anti-inflammatory effects, and assessment of inflammatory mediators by RT-qPCR in skin wound healing

Ethnopharmacological relevancePinus halepensis Mill. seed (Pinaceae), commonly known as “Zgougou,” is widely consumed in the Mediterranean region and has long been used to treat diseases including bronchitis, rheumatism, infection, and inflammation. Aim of the studyThe present study was focused on the investigation of some pharmacological activities, such as analgesic, anti-inflammatory, and wound healing effects, of cold-pressed oil of Pinus halepensis Mill. seed (COPHS). Materials and methodsThe fixed oil of Pinus halepensis seed was extracted by a cold pressing process. The analgesic activity of COPHS was examined by acetic acid and formalin-induced contortion and pain tests. The anti-inflammatory effects were evaluated in carrageenan and formalin induced paw and ear edema models. Wound healing potential was assessed on an experimental skin wound, and the expression levels of inflammation mediators were determined by RT-qPCR in skin wound healing. ResultsThe results showed analgesic efficacy through significant inhibition of abdominal cramps (59.15%) and pain (75.91%). In addition, this oil exerted an anti-inflammatory effect by inhibiting ear (62.25%) and paw (70.00%) edema. The COPHS stimulated wound contraction in experimental skin wound healing with a contraction rate of 89.23% with notable reduction of TNF-α and NF-kB expression levels in the treated groups. ConclusionsThis study provided for the first time the pharmacological profile, particularly the analgesic, anti-inflammatory, and healing effects, of fixed oil extracted by cold pressing from the seed of Pinus halepensis Mill.

The nutritional composition of six plant species after irrigation with treated wastewater and possible hazards by heavy metal accumulation.

A field experiment was conducted investigating the possibility of using treated wastewater (TWW) on sites affected by water scarcity in summer, waterlogging during the wet season, and salinity. A corresponding pot experiment was conducted comparable to the field experiment in Kalaât Landelous. The same plant species (Atriplex nummularia Lindl., Eucalyptus gomphocephala DC., Acacia cyanophylla Lindl., Casuarina glauca Sieber ex Spreng., Cupressus sempervirens L., and Pinus halepensis Mill.) were grown with the same treatments. While, in the field the plants, elemental composition cannot be linked to inputs by TWW, this was studied under controlled conditions. Additionally, a control was established lower in salinity receiving tap water. The effect of TWW irrigation on macro- and microelement uptake by the six plant species was studied. The treatments were high soil salinity under drained saline (DS) conditions, high salinity under waterlogged saline (WS), and a drained non-saline control (DNS: EC = 3.0 dS/m, pH = 8.4). TWW application under DS treatment increased Na, Cl, Ca, Mg, N, P, and K in most plant tissues compared to the control. TWW application in WS treatment resulted in an increase in heavy metals. Cu and Zn showed the highest bioaccumulation factor (BAF). The BAF in different plant tissues followed the order: Cu > Zn > Mn > Cd > Ni > Co > Pb. The plants accumulated significant amounts of metals in their roots.

Short-term Macrochloa tenacissima response understory Pinus halepensis Mill forest after early prescribed burns in a semi-arid landscape

Climate change has led to altered fire patterns in the Mediterranean basin due to rising temperatures and greenhouse gas emissions, diminishing the resilience of forest ecosystems. To address this threat, forest management increasingly employs preventive measures like controlled burns, aiming to mitigate wildfire damage. However, understanding the impact of prescribed burns on vegetation remains crucial.Our study focuses on assessing the ecological effects of early-season prescribed burns on Macrochloa tenacissima communities within Pinus halepensis Mill forests on the Iberian Peninsula. These forests, with southeast-facing slopes and arid soils, heavily rely on alpha grass for post-fire recovery, acting as a shield against runoff and erosion. Yet, the presence of highly flammable resprouting species can lead to rapid combustible material accumulation. We evaluated parameters like coverage, floral diversity (α-diversity), aboveground plant biomass, photosynthetic activity, and chemical leaf properties of alpha grass, a year after a low-intensity controlled burn. Comparing burnt and unburnt areas revealed significant changes in α-diversity and ecophysiology of Macrochloa tenacissima due to early-season prescribed burns. These short-term shifts underscore the need for further exploration of underlying mechanisms.Our analysis also showed distinct shifts in alpha grass leaf chemical composition between the two plot types, potentially impacting post-fire recovery strategies. Although prescribed burning might not be optimal for reducing fire risk in resprouting species-dominated forests, it conserves native plants and enhances ecosystem diversity, providing valuable ecological benefits.In conclusion, our research deepens our understanding of early-season burning's repercussions on flammable vegetation dynamics and combustible material availability in semi-arid landscapes. It contributes to standardized management protocols, aiding effective forest service administration and wildfire risk reduction.

Medicinal plants used for the treatment of respiratory diseases in Kabylia, north of Algeria: an ethnomedicinal survey

IntroductionRespiratory diseases are a major health problem in developing countries, including Algeria. Our study aimed to document the indigenous knowledge about the use of medicinal plants in the Kabylia region of Algeria, for the treatment of respiratory diseases. MethodsAn ethnobotanical survey was conducted in eight localities of the Tizi-Ouzou province (Kabylia) from August 2019 to January 2020. A total of 105 informants, including herbalists, doctors, botanists, and rural dwellers, were interviewed using a semi-structured questionnaire. The frequency citation (FC), relative frequency citation (RFC), and informant consensus factor (ICF) were calculated to analyze the data. ResultsOut of the 105 informants, women were the dominant gender (67.62%), with an average age of about 64 years, while men (32.38%) had an average age of 62 years. A total of 42 plant species belonging to 23 families used for the treatment of chronic respiratory inflammation were reported. Lamiaceae was the most cited family (46%), represented by nine species. Interestingly, Thymus numidicus Poir., an Algerian endemic plant, was reported for the first time to treat cold, flu, and asthma. In addition, Arum italicum Mill. and Pinus halepensis Mill. were described as remedies for asthma symptoms, essentially wheezing. A high-value ICF (0.94–0.97) was estimated for six respiratory ailments, including asthma, pulmonary obstruction, cough, wheezing, bronchitis, and respiratory infections. Leaves (56%) were the most widely used plant part, and infusion (42%) was the most cited preparation method. ConclusionOur study showed rich ethnomedical knowledge in the Kabylia region regarding the use of medicinal plants for the treatment of respiratory diseases. The most reported species could be of great interest for further pharmacological studies.

Individual-tree growth system for even-aged Aleppo pine plantations in Aragón, Spain

Aim of study: An individual-tree growth system was developed for Aleppo pine (Pinus halepensis Mill.) plantations.
 Area of study: Aragón region (Northeast Spain).
 Material and methods: Two datasets were used: Second and Third Spanish National Forest Inventories (104 plots with 1,678 trees), and ad hoc permanent plots (58 plots with 1720 trees, including 36 dead trees). Individual tree growth system was based on nine models. Different combinations of yield classes, initial stocking rates, thinning parameters, rotation periods, and age at first thinning were evaluated through the three most representative scenarios: timber production; soil conservation and biodiversity enhancement.
 Main results: The nine models demonstrated a significant explanatory power for the data, with R2 values ranging from 0.71 to 0.99. These findings are consistent with previous research, indicating a strong goodness of fit. Additionally, yield tables were developed for the three prevalent silvicultural scenarios. To enhance usability, all models within the system were seamlessly integrated into a web-based application SIMANFOR.
 Research highlights: To date, Aleppo pine forest managers in Aragon could only simulate silvicultural scenarios in natural stands. This study provides a new tool for plantations.

Pre- and post-drought conditions drive resilience of Pinus halepensis across its distribution range

Severe droughts limit tree growth and forest productivity worldwide, a phenomenon which is expected to aggravate over the next decades. However, how drought intensity and climatic conditions before and after drought events modulate tree growth resilience remains unclear, especially when considering the range-wide phenotypic variability of a tree species.We gathered 4632 Aleppo pine (Pinus halepensis Mill.) tree-ring width series from 281 sites located in 11 countries across the Mediterranean basin, representing the entire geographic and bioclimatic range of the species. For each site and year of the period 1950–2020, we quantified tree-growth resilience and its two components, resistance and recovery, to account for the impact of drought and the capacity to recover from it. Relative drought intensity of each year was assessed using SPEI (Standardized Precipitation Evapotranspiration Index), a climatic water deficit index. Generalized additive mixed models were used to explore the non-linear relationships between resilience and its two components and drought intensity, preceding and following years climatic conditions.We found that P. halepensis radial growth was highly dependent on the SPEI from September of the previous year to June of the current year. Trees growing under more arid bioclimates showed higher inter-annual growth variability and were more sensitive to drought, resulting in an increased response magnitude to pre-, during and post-drought conditions. In contrast to our expectations, drought intensity only slightly affected resilience, which was rather negatively affected by favorable preceding conditions and improved by favorable following conditions.Resilience and its components are highly dependent on preceding and following years climatic conditions, which should always be taken into account when studying growth response to drought. With the observed and predicted increase in drought frequency, duration and intensity, favorable conditions following drought episodes may become rare, thus threatening the future acclimation capacity of P. halepensis in its current distribution.

Chloroplast microsatellite diversity of Pinus brutia Ten. and Pinus halepensis Mill. populations across the Mediterranean basin: Inferences of their distributions

Aim of study: To characterize and compare the genetic resources and gain some insights into the evolutionary history of Aleppo pine (Pinus halepensis Mill.) and Brutia pine (Pinus brutia Ten.) species which are both distributed across more than 8 million hectares of area in the Mediterranean Basin.
 Study area: Fifty-six populations from eight Mediterranean basin countries where P. halepensis and P. brutia species are located.
 Materials and methods: We analyzed 1344 seeds belonging to 56 populations using five cpSSR primers (Pt15169, Pt30204, Pt41093, Pt87268, and Pt110048).
 Main results: The analysis of molecular variance (AMOVA) revealed that the genetic diversity among the Brutia pine populations was slightly higher than that of Aleppo pine (27.06% and 24.27%, respectively). The Aleppo pine populations separately displayed a clear east-west differentiation across the Mediterranean Basin, confirming previous results using other markers. Although the Brutia pine populations showed no spatial genetic pattern, geographically close populations and/or populations from their continual distribution range were genetically closer than the fragmented and/or ecologically marginal populations.
 Research highlights: The seven Aleppo pine populations from the eastern range (Türkiye, Greece, and Italy) were more than two-fold diverse than the 13 populations from the western range (Spain and Morocco). The eastern range of Aleppo pine and Brutia pine populations had similar levels of genetic diversity parameters. These results suggested that the Eastern Mediterranean Basin is a possible genetic diversity center for the two pine species.

Medium-term effects of wildfire severity on soil physical, chemical and biological properties in Pinus halepensis Mill. woodland (Southern Italy): an opportunity for invasive Acacia saligna colonization?

Wildfire frequency and severity have greatly increased in Mediterranean areas in recent decades affecting ecosystems functioning due to alteration in the above- and below-ground process. This study aimed to investigate how wildfire severity, in the medium-term (2–5 years), impacts soil properties within a Pinus halepensis woodland located in the Special Area of Conservation (SAC) of the Natura 2000 network (IT9130006 - Pinewoods of the Ionian Arch). In 2021, four years after a large wildfire in 2017, the woodland still exhibited fire effects with evidence of low, medium or high burn severity in different sites (named LBS, MBS, HBS, respectively). In addition, we observed an area burnt at medium severity that was invaded by Acacia saligna (MBSA site), a fast-growing, highly invasive, drought-tolerant nitrogen-fixing plant, thus we also examined the combined effect of wildfire and A. saligna on the soil. We compared soil properties across burnt sites with a nearby unburnt site (control). Thickness, weight and organic carbon of litter (L) and fermentation (F) layers were measured, alongside physical, chemical and biological properties in the underlying mineral soil (0–10 cm). Our results show that wildfire destroyed the organic layers and these had not recovered four years after the wildfire (except for L-layer within LBS) with a consequent loss (∼2 t C ha−1) of this carbon pool. In mineral soil we identified fourfold increases in N mineralization and nitrification rates across all burnt sites, regardless of the burn severity and A. saligna presence, suggesting an alteration of N-cycle processes. On the contrary, total microbial biomass and soil respiration as well as most of the physical and chemical properties of the soil were comparable between the burnt and control soils. Principal Component Analysis (PCA) highlighted that burn severity affected soil variables with lower changes in LBS than in other burnt soils. Also, the HBS soil did not show greater negative impacts compared to MBS sites. This is probably due to the increased post-fire colonization by herbaceous plants in HBS, favoured by the complete destruction of trees. In this case, waiting for natural vegetation recovery can be a valid management option, but periodic monitoring of fire-soil-vegetation interaction mainly to avoid invasive species widespread is advocated.

Functional responses of two Mediterranean pine species in an ozone Free-Air Controlled Exposure (FACE) experiment.

Effects of the phytotoxic and widespread ozone (O3) pollution may be species specific, but knowledge on Mediterranean conifer responses to long-term realistic exposure is still limited. We examined responses regarding to photosynthesis, needle biochemical stress markers and carbon and nitrogen (N) isotopes of two Mediterranean pine species (Pinus halepensis Mill. and Pinus pinea L.). Seedlings were grown in a Free-Air Controlled Exposure experiment with three levels of O3 (ambient air, AA [38.7p.p.b. as daily average]; 1.5×AA and 2.0×AA) during the growing season (May-October 2019). In P. halepensis, O3 caused a significant decrease in the photosynthetic rate, which was mainly due to a reduction of both stomatal and mesophyll diffusion conductance to CO2. Isotopic analyses indicated a cumulative or memory effect of O3 exposure on this species, as the negative effects were highlighted only in the late growing season in association with a reduced biochemical defense capacity. On the other hand, there was no clear effect of O3 on photosynthesis in P. pinea. However, this species showed enhanced N allocation to leaves to compensate for reduced photosynthetic N- use efficiency. We conclude that functional responses to O3 are different between the two species determining that P. halepensis with thin needles was relatively sensitive to O3, while P. pinea with thicker needles was more resistant due to a potentially low O3 load per unit mass of mesophyll cells, which may affect species-specific resilience in O3-polluted Mediterranean pine forests.

Mitigation of Global Climate Change through Genetic Improvement of Resin Production from Resinous Pines: The Case of Pinus halepensis in Greece

Carbon sequestration by forests and storage in biomass has gained great interest globally in climate change mitigation. Resinous pine forests act as ideal carbon sinks because, in addition to capturing atmospheric CO2 for biomass production, they produce resin (resin concentration in C: 77.17% w/w), contributing further to the mitigation of the greenhouse effect. Greece until the 1970s was considered one of the main resin-producing countries of Europe, due to the quantity and quality of resin products collected from natural populations mainly of Pinus halepensis Mill. Previous and current research has shown that resin production is a genetically controlled trait (h2 > 0.70) that exhibits great variability among trees (resin 0.5–33.0 kg per tree and year). The above led to the genetic selection of P. halepensis genotypes with constant over time high resin yields (≥20 kg per tree and year) and consequently greater atmospheric CO2 sequestration for more effective counteracting climate change but also for economic reasons for the benefit of resin producers. These high-yielding genotypes were cloned through grafting on P. brutia rootstocks and became potential trees for establishing commercial pine plantations. Thus, one hectare of commercial plantation of 500 P. halepensis trees, with a resin yield of 20 kg per tree, is expected to sequester 28.31 tn CO2 per year (instead of 2.82 tn of CO2 per year of a natural stand of 400 P. halepensis trees based on a resin yield of 2.5 kg per tree), at the productive age of 25 years. In this case, commercial plantations with improved genotypes of P. halepensis have great potential not only in mitigating the concentration of CO2 in the atmosphere, but also in restoring degraded marginal areas and arid soils, and at the same time can offer social and economic benefits to the local communities.

Proteomic and Metabolic Analysis of Pinus halepensis Mill. Embryonal Masses Induced under Heat Stress.

Understanding the physiological and molecular adjustments occurring during tree stress response is of great importance for forest management and breeding programs. Somatic embryogenesis has been used as a model system to analyze various processes occurring during embryo development, including stress response mechanisms. In addition, "priming" plants with heat stress during somatic embryogenesis seems to favor the acquisition of plant resilience to extreme temperature conditions. In this sense, Pinus halepensis somatic embryogenesis was induced under different heat stress treatments (40 °C for 4 h, 50 °C for 30 min, and 60 °C for 5 min) and its effects on the proteome and the relative concentration of soluble sugars, sugar alcohols and amino acids of the embryonal masses obtained were assessed. Heat severely affected the production of proteins, and 27 proteins related to heat stress response were identified; the majority of the proteins with increased amounts in embryonal masses induced at higher temperatures consisted of enzymes involved in the regulation of metabolism (glycolysis, the tricarboxylic acid cycle, amino acid biosynthesis and flavonoids formation), DNA binding, cell division, transcription regulation and the life-cycle of proteins. Finally, significant differences in the concentrations of sucrose and amino acids, such as glutamine, glycine and cysteine, were found.

Improving Sustainable Forest Management of Pinus halepensis Mill. Mid-Aged Stands in a Context of Rural Abandonment, Climate Change, and Wildfires

Pinus halepensis Mill. covers most lowland forests on limestone soils and semiarid to sub-humid climates in the Mediterranean basin. It is considered a key species in climate change due to its pioneer nature, versatility, and flexibility. Moreover, its industrial potential is an additional incentive to promote forest management to increase its quality and productivity while contributing to other environmental and social objectives. However, there is a considerable gap in science-based knowledge on the effects of different silvicultural treatments on Pinus halepensis stands. Thus, this research compares the impact of four different treatments (light thinnings, strong thinnings, transformation to uneven-aged, and diameter-driven uneven-aged) on even-aged mid-rotation stands of Pinus halepensis in terms of growth, vulnerability, and resilience to extreme weather events, regeneration, and shrub cover. The effects of four treatments are evaluated in 12 research plots of 0.49 ha each (three per treatment) and contrasted with the other three non-managed control plots. Light and strong thinning treatments show better growth—at least in the short term—and stock results than those reported in the reference yield tables. Transformation to uneven-aged treatment shows advantages in maintaining periodic growth, regeneration, and stability. In addition, it offers an alternative for steep slope stands, smallholders, and extended narrow-aged estates to speed up the desirable balanced age class distribution. Diameter-driven uneven-aged treatment implies greater vulnerability to extreme weather events during the first years and considerable stock reduction while offering faster and taller tree regeneration. A dual regeneration pattern of Ulex parviflorus Pourr is observed in addition to post-fire regeneration in the case of sudden and well-distributed tree cover reduction around 40% of the canopy due to the transformation into the uneven-aged stand. An observation period longer than a decade of the research plots will confirm these first conclusions.

Aboveground responses to belowground root damage detected by non-destructive sensing metrics in three tree species

Abstract Root systems form a significant part of tree biomass and function. Yet, roots are hidden from our eyes, making it difficult to track the belowground processes. By contrast, our capacity to detect aboveground changes in trees has been continuously improving using optical methods. Here, we tested two fundamental questions: (1) To what extent can we detect aboveground responses to mechanical damage of the root system? (2) To what extent are roots redundant? We applied three different non-destructive remote sensing means: (1) optical means to derive leaf greenness, (2) infrared means to detect the changes in leaf surface temperature and (3) spectral means to derive five vegetation indices (i.e. the photochemical reflectance index (PRI), the chlorophyll photosynthesis index (CIRed-edge), the anthocyanin reflectance index 1, the structure insensitive pigment index and the normalized difference water index (NDWI)). We recorded the above metrics for hours and days and up to a month following induced root damage in three key Mediterranean tree species: Aleppo pine (Pinus halepensis Mill.), Palestine oak (Quercus calliprinos Webb.) and Carob (Ceratonia siliqua L.). To induce root damage, we removed 25, 50 and 75 percent of the root system in each species and compared it with control saplings. Tree aboveground (canopy) responses to root damage increased over time and with damage level. Leaf warming (up to 3°C) and decreased PRI were the most significant and rapid responses, with temperature differences being visible as early as 2 days following root damage. NDWI and greenness were the least sensitive, with responses detectable only at 75 percent root damage and as late as 14 or 30 days following root damage. Responses varied vastly among species, with carob being the most sensitive and pine being the least. Changes in leaf temperature and PRI indicated that leaf transpiration and photosynthesis were impaired by root damage. Although trees build roots in excess, mechanical damage will eventually decrease transpiration and photosynthesis across tree species.

Aleppo pine seeds (Pinus halepensis Mill.) as a promising novel green coagulant for the removal of Congo red dye: Optimization via machine learning algorithm

Consideration is now being given to the use of metal coagulants to remove turbidity from drinking water and wastewater. Concerns about the long-term impact of non-biodegradable sludge on human health and the potential contamination of aquatic systems are gaining popularity. Recently, alternative biocoagulants have been suggested to address these concerns. In this study, using a 1 M sodium chloride (NaCl) solution, the active coagulating agent was extracted from Pinus halepensis Mill. Seed, and used for the first time to remove Congo red dye, the influence of numerous factors on dye removal was evaluated in order to make comparisons with conventional coagulants. The application of biocoagulant was shown to be very successful, with coagulant dosages ranging from 3 to 12 mL L−1 achieving up to 80% dye removal and yielding 28 mL L−1 of sludge. It was also found that biocoagulant is extremely pH sensitive with an optimum operating pH of 3. Ferric chloride, on the other hand, achieved similar removal rate with higher sludge production (46 mL L−1) under the same conditions. A Fourier Transform Infrared Spectroscopy and proximate composition analysis were undertaken to determine qualitatively the potential active coagulant ingredient in the seeds and suggested the involvement of proteins in the coagulation-flocculation mechanism. The evaluation criteria of the Support vector machine_Gray wolf optimizer model in terms of statistical coefficients and errors reveals quite interesting results and demonstrates the performance of the model, with statistical coefficients close to 1 (R = 0.9998, R2 = 0.9995 and R2 adj = 0.9995) and minimal statistical errors (RMSE = 0.5813, MSE = 0.3379, EPM = 0 0.9808, ESP = 0.9677 and MAE = 0.2382).The study findings demonstrate that Pinus halepensis Mill. Seed extract might be a novel, environmentally friendly, and easily available coagulant for water and wastewater treatment.

The effect of phytoecological factors on the natural regeneration of Aleppo pine (Pinus halepensis Miller, 1768) in semi-arid zones

The effect of phytoecological factors on the natural regeneration of Aleppo pine (Pinus halepensis Miller, 1768) in semi-arid zones

Stand characteristics modulate secondary growth responses to drought and gross primary production in Pinus halepensis afforestation

Impacts of climate warming on forests vigour are forecasted to increase in magnitude. Yet it remains unclear how stand characteristics and competition modulate the relationship between tree growth and gross primary production with drought. Here, we studied how the spatial variation in stand density, basal area and height modulates tree growth (Basal Area Increment, BAI and stand growth), summer NDVI, as well as their responses to drought (Standardized Precipitation-Evapotranspiration Index, SPEI) in 56 Aleppo pine (Pinus halepensis Mill.) planted forests located in Northeast Spain. Long-term BAI responses to SPEI were strongly determined by stand density, suggesting that competition modulates Aleppo pine growth responses to drought. Along this, summer NDVI also displayed strong associations with SPEI. NDVI was mostly related with stand growth, suggesting canopy densification drives NDVI pattern and trends. Short-term BAI and NDVI responses to severe droughts were mainly independent of stand characteristics. In the studied region, drought is a universal factor limiting Aleppo pine secondary growth and canopy greening. However, the results suggest that stand density modulates Aleppo pine growth responses to drought on the long-term, reducing the growth in densest stands. Denser stands with larger trees are the ones that present higher NDVI values, suggesting that canopy activity depends more on stand canopy coverage than on secondary growth rate and its response to drought. In these Mediterranean pines, canopy activity and secondary growth are temporally coupled but spatially decoupled.

Are Foliar Nutrition Status and Indicators of Oxidative Stress Associated with Tree Defoliation of Four Mediterranean Forest Species?

Mediterranean forest ecosystems in Croatia are of very high significance because of the ecological functions they provide. This region is highly sensitive to abiotic stresses such as air pollution, high sunlight, and high temperatures alongside dry periods; therefore, it is important to monitor the state of these forest ecosystems and how they respond to these stresses. This study was conducted on trees in situ and focused on the four most important forest species in the Mediterranean region in Croatia: pubescent oak (Quercus pubescens Willd.), holm oak (Quercus ilex L.), Aleppo pine (Pinus halepensis Mill.) and black pine (Pinus nigra J. F. Arnold.). Trees were selected and divided into two groups: trees with defoliation of >25% (defoliated) and trees with defoliation of ≤25% (undefoliated). Leaves and needles were collected from selected trees. Differences in chlorophyll content, hydrogen peroxide content, lipid peroxidation and enzyme activity (superoxide dismutase, catalase, ascorbate peroxidase, non-specific peroxidase), and nutrient content between the defoliated and undefoliated trees of the examined species were determined. The results showed that there were significant differences for all species between the defoliated and undefoliated trees for at least one of the examined parameters. A principal component analysis showed that the enzyme ascorbate peroxidase can be an indicator of oxidative stress caused by ozone. By using oxidative stress indicators, it is possible to determine whether the trees are under stress even before visual damage occurs.