Aleppo pine (Pinus halepensis Mill.) in dendroflora оf Belgrade

An investigation of selected Aleppo pines in the forests of Mt Hymettus and Mt Parnis near Athens (Greece) was undertaken at three different sites in the period 1999–2003, because a considerable proportion of pine trees showed visible signs of chlorotic mottle. This condition is characteristic of high and prolonged levels of ozone exposure. Needles from Aleppo pine trees (Pinus halepensis Mill.) were analyzed for their manganese content in combination with Electron Paramagnetic Resonance (EPR) spectra of Mn2+, involved in photosystem II. Manganese is considered as an important bioindicator for the vitality of trees. Also, we investigated the EPR spectrum of the needles in the region of g=2.0045 for “healthy” and “diseased” trees. The antioxidant capacity of the needles’ extract was measured from trees by the DPPH method. Finally, seasonal changes in chlorophyll concentration in the needles were measured to evaluate the effects of ozone. Measurements of ozone concentrations at the three sites showed that there were elevated levels during the summer months. Our experimental results suggest that the concentration of manganese in the needles was lower in the area with higher ozone concentrations, supported by EPR measurements. Higher ozone concentrations also affected the antioxidant potential of the needles and their chlorophyll content during summer months. Our findings also confirmed the resilience of Aleppo pines under stressful conditions and recovery in winter months. Despite the experimental problems, EPR spectra of Mn2+ in combination with other methods can be used as a sensitive bioindicator for ozone pollution, and is the result of oxidative stress affecting the growth cycle of the pine trees and their photosynthetic mechanisms.

Tree 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.

Autecology and growth of Aleppo pine ( Pinus halepensis Mill.): A comprehensive study in France

Climate change represents an important challenge for forest management and the silviculture of stands and it is known that climate change will have complex effects on cork oak forest ecosystems. North Africa and the Mediterranean basin are especially vulnerable to climate change. Under the effect of climate change, cork oak will disappear from a large area in the future, and the rest will migrate to higher altitudes and latitudes. This study aimed to evaluate the effect of climate change on the spatial distribution of Quercus suber L. and cork production in the Mediterranean area, and the risk of its exclusion by the Aleppo pine (Pinus halepensis Mill.) expansion. The literature review showed that up to 40% of current environmentally suitable areas for cork oak may be lost by 2070, mainly in northern Africa and the southern Iberian Peninsula. Temperature directly influences atmospheric evaporative demand and should affect cork productivity. Precipitation is the main factor that positively influences cork growth and several authors have confirmed the negative effect of drought on this growth. Currently, cork oak habitats are colonized in several places mainly by the Aleppo pine. Under climate change, Aleppo pine is projected to occupy higher altitude sites and several authors have predicted that current and future global warming will have a positive influence on Aleppo pine growth in wet sites. In the future and under climate change, there is a strong possibility that the Aleppo pine will colonize cork oak habitat. Finally, we proposed management practices to protect cork oak against climate change and Aleppo pine expansion.

In this work, the hypothesis of the convenience of merging data of complementary techniques to carry out forest inventories is tested by fusing data from Remotely Piloted Aircraft System Digital Aerial Photogrammetry (RPAS-DAP) and Terrestrial Laser Scanning (TLS). The work area was in the Natural Park Sierra Maria-Los Velez (Almeria, Spain), constituted of a representative Mediterranean forest composed of two main forest layers: i) predominant trees (reforested Aleppo pine (Pinus halepensis Mill.)), and ii) understory forest (holm oak (Quercus ilex L.) and different shrubs species). An Object Based Image Analysis (OBIA) pipeline was applied over the corresponding RPAS-DAP RGB orthoimage and a high-resolution Canopy Height Model (CHM) directly derived from the image-based point cloud. This allowed the automatic obtaining of tree delineation, species classification and forest structural attributes (tree height, position and projected crown area). Geometric features derived from the CHM and Green Leaf Index were used to feed a tailored devised OBIA-based method. The very high-resolution fused point cloud, made up from combining TLS and RPAS-DAP point clouds, provided tree-based biometric information such as tree position, diameter at breast height, crown projected area and tree height to estimate forest Above-Ground dry Biomass (AGB) for predominant trees through the allometric equation corresponding to Aleppo pine. In conclusion, the results obtained from the pipeline proposed in this work have shown the complementarity of RPAS image-based methods and TLS to provide timely and efficiently high value-added products such as forest AGB and tree species spatial distribution over Mediterranean forest.

Aleppo pine is one of the most important coniferous trees in the Algerian natural forests, where it plays a major role in the rehabilitation of degraded soils and provides a valuable renewable raw material for local populations. However, during the last decades Aleppo pine forests have known an alarming regression in Algeria due to anthropogenic pressure, wildfires and climate changes. Under these conditions there is urgently needed to locate better seed provenances for future reforestation projects. Several works have been conducted to assess the influence of provenance on the biometric features of cones and seeds in Pinus halepensis Mill. However, the influence of provenance on these morphometric traits in Algerian Aleppo pine, particularly in arid zones, remains poorly understood. This study aims to study the variability of biometric characteristics of cones, seeds and wings of P. halepensis growing in four separate provenances in Djelfa province, Algeria. From each provenance ten elite trees were randomly selected, and one hundred ripe cones (n = 100) were collected for biometric measurements. Results indicated that cone and seed traits of the four provenances were significantly different (P < 0.001). Mean values of cone weight (CW), cone length (LC), 1000-seed weight (1000 SW), and seed length (SL) were higher in Senalba Chergui forest, while the average value of cone diameter (CD) was higher in Senalba Gharbi. No significant variation (P > 0.05) was observed among different provenances for seed width (SW). Using principal component analysis (PCA), seed traits (SL, SW, WL, WW, and 1000 SW) were the most important characters in the first principal component (PC1), however cone traits (CL, and CW) were the more important morphometric parameters in the second principal component (PC2). PCA reveals that seed traits are more important for evaluating provenance performance than cone traits. This paper provides results will fill the gap in Aleppo pine genetic resource usage and present guidelines for future breeding programms in area of Algeria. The existence of these variabilities on cones and seeds among Aleppo pine provenances provides further issues to study whether there are related with seed germination to choice the best provenance for artificial regeneration purposes.

The implementation of Unmanned Aerial Vehicles (UAVs) and Structure-from-Motion (SfM) photogrammetry in assessing forest structures for forest inventory and biomass estimations has shown great promise in reducing costs and labour intensity while providing relative accuracy. Tree Height (TH) and Diameter at Breast Height (DBH) are two major variables in biomass assessment. UAV-based TH estimations depend on reliable Digital Terrain Models (DTMs), while UAV-based DBH estimations depend on reliable dense photogrammetric point cloud. The main aim of this study was to evaluate the performance of multi-rotor UAV photogrammetric point cloud in estimating homogeneous and heterogeneous forest structures, and their comparison to more accurate LiDAR data obtained from Aerial Laser Scanners (ALS), Terrestrial Laser Scanners (TLS), and more conventional means like manual field measurements. TH was assessed using UAVSfM and LiDAR point cloud derived DTMs, while DBH was assessed by comparing UAVSfM photogrammetric point cloud to LiDAR point cloud, as well as to manual measurements. The results obtained in the study indicated that there was a high correlation between UAVSfM TH and ALSLiDAR TH (R2 = 0.9258) for homogeneous forest structures, while a lower correlation between UAVSfM TH and TLSLiDAR TH (R2 = 0.8614) and UAVSfM TH and ALSLiDAR TH (R2 = 0.8850) was achieved for heterogeneous forest structures. A moderate correlation was obtained between UAVSfM DBH and field measurements (R2 = 0.5955) for homogenous forest structures, as well as between UAVSfM DBH and TLSLiDAR DBH (R2 = 0.5237), but a low correlation between UAVSfM DBH and UAVLiDAR DBH (R2 = 0.1114). The study demonstrated that UAV acquired imagery can be used to accurately estimate TH in both forest types, but has challenges estimating DBH. The research does not suggest that UAVSfM serves as a replacement for more high-cost and accurate LiDAR data, but rather as a cheaper adequate alternative in forestry management depending on accuracy requirements.

SummaryXylem embolism impairs hydraulic conductivity in trees and drives drought‐induced mortality. While embolism has been monitored in vivo in potted plants, and research has revealed evidence of embolism in field‐grown trees, continuous in situ monitoring of cavitation in forests is lacking.Seasonal patterns of embolism were monitored in branchlets of Aleppo pine (Pinus halepensis) trees growing in a dry Mediterranean forest. Optical visualization (OV) sensors were installed on terminal branches, in addition to monthly sampling for micro computed tomography scans.We detected 208 cavitation events among four trees, which represented an embolism increase from zero to c. 12% along the dry season. Virtually all the cavitation events occurred during daytime hours, with 77% occurring between 10:00 and 17:00 h. The probability for cavitation in a given hour increased as vapor pressure deficit (VPD) increased, up to a probability of 42% for cavitation when VPD > 5 kPa.The findings uniquely reveal the instantaneous environmental conditions that lead to cavitation. The increased likelihood of cavitation events under high VPD in water‐stressed pines is the first empirical support for this long hypothesized relationship. Our observations suggest that low levels of embolism are common in Aleppo pine trees at the dry edge of their distribution.

Allometric equations for the estimation of crown fuel weight of Aleppo pine (Pinus halepensis Mill.) trees in the Mediterranean Basin were developed. Forty trees were destructively sampled and their crown fuels were weighed separately for each fuel category. Crown fuel components, both living and dead, were separated into size classes and regression equations that estimate crown fuel load by diameter class were derived. The allometric equation y = axb with diameter at breast height as the single predictor was chosen, because the addition of other parameters did not decrease the residual sum of squares significantly. The adjusted coefficient of determination (R2adj) values were high (R2adj = 0.82–0.88) in all cases. Diameter at breast height was the most significant determinant of crown fuel biomass. The aerial fuels that are consumed during crown fires (i.e. needles and twigs with diameter less than 0.63 cm) comprised 29.3% of the total crown weight. Live fuels constituted ~96.3% of total crown biomass, distributed as follows: needles 16.7% (average load 12.07 kg), branches with 0.0–0.63-cm diameter 12.6% (average load 9.18 kg), 0.64–2.5-cm diameter 37.3% (27.99 kg), 2.51–7.5-cm diameter 25.4% (18.59 kg), and &amp;gt;7.5-cm diameter 3.7% (2.65 kg). The equations provide quantitative fuel biomass attributes for use in crown fire behaviour models, fire management and carbon assessment in Aleppo pine stands.

Abundant and refined structural information under forest canopy can be obtained by using terrestrial laser scanning (TLS) technology. This study explores the methods of using TLS to obtain point cloud data and estimate individual tree height and diameter at breast height (DBH) at plot level in regions with complex terrain. Octree segmentation, connected component labeling and random Hough transform (RHT) are comprehensively used to identify trunks and extract DBH of trees in sample plots, and tree height is extracted based on the growth direction of the trees. The results show that the topography, undergrowth shrubs, and forest density influence the scanning range of the plots and the accuracy of feature extraction. There are differences in the accuracy of the results for different morphological forest species. The extraction accuracy of Yunnan pine forest is the highest (DBH: Root Mean Square Error (RMSE) = 1.17 cm, Tree Height: RMSE = 0.54 m), and that of Quercus semecarpifolia Sm. forest is the lowest (DBH: RMSE = 1.22 cm, Tree Height: RMSE = 1.23 m). At plot scale, with the increase of the mean DBH or tree height in plots, the estimation errors show slight increases, and both DBH and height tend to be underestimated.

Do climate and human disturbance determine the sizes of endangered Metasequoia glyptostroboides trees in their native range?

The Aleppo pine (Pinus halepensis Miller) trees grown in the agricultural lands with high biodiversity, and considered as a potential source for chemical and therapeutic compounds. Essential oil (EO) and n-butanol fraction (But-fr) of Aleppo pine cones were evaluated against the growth of four plant bacterial pathogens (Dickeya solani, Pectobacterium atrosepticum, Ralstonia solanacearum, and Agrobacterium tumefaciens) and four human pathogenic bacteria (Bacillus subtilis ATCC 6633, Sarcina lutea ATCC 9341, Escherichia coli ATCC 8739, and Staphylococcus aureus ATCC 6538). The diameter of the inhibition zone (IZ) and the minimum inhibitory concentrations (MICs) were measured. At 2000 μg/mL, But-fr showed the strongest activity against D. solani, P. atrosepticum, and R. solanacearum with inhibition zones (IZs) of 14.33 mm, 12.33 mm, and 15.33 mm, respectively. At 2000 μg/mL, EO showed the best activity against A. tumefaciens with an IZ value of 12.67 mm. Weak activity was observed by applying the EO and But-fr against B. subtilis and S. lutea, while good activity was recorded by But-fr against E. coli and S. aureus with IZs values of 13.67 mm and 11.33 mm, respectively, at 2000 μg/mL. Gas chromatography-mass spectrometry (GC/MS) analysis reported that the EO from cones contained mainly caryophyllene (15.17%), α-pinene (13.51%), and caryophyllene oxide (12.57%); But-fr contained 3,4-dimethyldihydrofuran-2,5-dione (36.25%), and 2-methylenecholestan-3-ol (18.12%). The phytochemical But-fr extract of Aleppo pine cones demonstrated moderate antibacterial effects against the studied bacteria.

Aleppo pine (Pinus halepensis Mill.) is widespread in most countries of the Mediterranean area. In Greece, Aleppo pine forms natural stands of high economic and ecological importance. Understanding the species’ ecophysiological traits is important in our efforts to predict its responses to ongoing climate variability and change. Therefore, the aim of this study was to assess the seasonal dynamic in Aleppo pine gas exchange and water balance on the leaf and canopy levels in response to the intra-annual variability in the abiotic environment. Specifically, we assessed needle gas exchange, water potential and δ13C ratio, as well as tree sap flow and canopy conductance in adult trees of a mature near-coastal semi-arid Aleppo pine ecosystem, over two consecutive years differing in climatic conditions, the latter being less xerothermic. Maximum photosynthesis (Amax), stomatal conductance (gs), sap flow per unit leaf area (Ql), and canopy conductance (Gs) peaked in early spring, before the start of the summer season. During summer drought, the investigated parameters were negatively affected by the increasing potential evapotranspiration (PET) rate and vapor pressure deficit (VPD). Aleppo pine displayed a water-saving, drought avoidance (isohydric) strategy via stomatal control in response to drought. The species benefited from periods of high available soil water, during the autumn and winter months, when other environmental factors were not limiting. Then, on the leaf level, air temperature had a significant effect on Amax, while on the canopy level, VPD and net radiation affected Ql. Our study demonstrates the plasticity of adult Aleppo pine in this forest ecosystem in response to the concurrent environmental conditions. These findings are important in our efforts to predict and forecast responses of the species to projected climate variability and change in the region.

The most interesting factors associated with seed and cone production of Aleppo pine were largely reviewed to identify broad patterns and potential effectiveness of reforestation efforts and planning. Aleppo pine cone production and seed yields are relatively variable, with differences between spatial and temporal influences. These differences are considered, mainly between (i) year, (ii) stand characteristics and (iii) individual tree measurements. Annual variability among populations was recorded for cone production per tree, based on influencing factors such as genetic characteristics, wetness, nutrient availability, insect pests and disease. In addition, some factors may affect Aleppo pine tree growth directly but may be affecting seed and cone production indirectly. Therefore, reduced stand density results in less competition among Aleppo pine trees and accompanying understory flora, which subsequently increases the stem diameter and other tree dimensions, including seed production. This review suggests that reforestation planning, particularly thinning, will result in improved tree morphology that will increase Aleppo pine seed and cone crops. Wildfire intensity and stand conditions such as light and soil nutrient status are also examined.

Understanding the relationship between diameter breast height (dbh), tree height and volume helps in optimizing log selection for different purposes based on required timber volume. The purpose of the study was to create a modified model for diameter breast height, tree height and volume for Pinus caribaea to adequately fit all relevant variations in the data using R programme. Dbh is better predictor variable compared to tree height when volume is considered as a response variable. But this alone could not meet the assumptions of linear regression model. This therefore prompted the use of all data collected where by the tree height was considered as random effect. This was useful in the fitting of all data of the collected variables to a more useful relation in estimation of their linear regression relationship. The accuracy of this model was improved by addition of log function. Data of Pinus caribaea tree volume, dbh and height was collected. One hundred (100) trees were sampled in 1 hectare of pinus plantation with a range of corresponding tree dbh and height across the plantation in to a data set known as “mypinedata”. We wanted to know how dhb and height of Pinus caribaea as predictor variables affected its volume as a response variable. Comparison of dbh and height for best predictor variable for volume as a response in the linear regression model showed dbh as a preferred variable. However to meet the assumptions the linear relationship of volume, dbh and height was modified to fit all relevant data to improve on the model. The modified model for dbh- volume linear relationship was consequently created to cater for the adequate fit of the data or relevant variations using height as a random effect. Therefore modified model proved better fit for volume, dbh and height relationship in Pinus caribaea stand as deduced from its data summary and the assumptions when the log function was added. The assumptions for the modified model were met for the plot of residua