•Mediterranean pine forests face warmer conditions and drought stress.•We quantify post-drought growth resilience along an altitudinal gradient.•The low-elevation limit of Scots pine showed the ...lowest resilience.•Black pine presented a high resilience at low elevation.•Analyses of growth resilience allow anticipating shifts of tree species.
Mediterranean pine forests are at risk of experiencing a decline in tree growth in response to climate warming if rising temperatures amplify drought stress. In mountain areas, tree growth could be enhanced in temperature-limited high elevations, whilst it might decline at water-constrained low elevations. Species differential responses could, however, modulate the impact of drought on forests along altitudinal gradients. To test for evidence of species differential drought impacts along an altitudinal gradient, we studied the growth responses of two Iberian pine species (Pinus sylvestris and Pinus nigra) subjected to Mediterranean conditions in Eastern Spain. We analysed the stability of growth (basal area increment) responses to climate and drought during the 1950–2014 period by using resistance and resilience indices. Pinus sylvestris growth was enhanced by warm spring temperatures, while Pinus nigra growth was improved by a positive spring water balance. Pinus sylvestris growth decreased temporally at the lower end of its altitudinal range, whereas Pinus nigra growth decreased at the upper end. Pinus sylvestris exhibited low growth stability at its low-elevation limit. Pinus nigra resistance also decreased along its altitudinal range, but this effect was compensated by a high resilience. In mixed stands the results were contrasting, with Pinus sylvestris (at the lower altitudinal range) being more vulnerable to drought-induced growth decline than Pinus nigra (at the upper altitudinal range). Under more severe and frequent dry spells, Pinus sylvestris at low altitude may be highly vulnerable to water shortage while Pinus nigra performs better. These growth responses are in line with the expectation of a contraction in the realized niche of Pinus sylvestris with extirpation of low-elevation stands if warmer and drier conditions continue. Moreover, we show that analysing growth resilience in response to drought is a useful method to anticipate likely changes in species dominance and thus to assist managers in designing forest adaptation strategies.
Exhaustion of stratospheric ozone found at a height of 10–30 km around the world causes the solar UV-B (280–320 nm) radiation to penetrate through the atmosphere more, and thus to reach the Earth’s ...surface quicker. The protective ozone layer gets damaged by human activities constantly, and the increasing levels of UV radiation present threats to all life forms, plants, animals, and even microorganisms. However, the studies conducted on the effects of UV radiation on plants, and especially forest trees, are rather limited. In this study, it was aimed to identify the effects of UV-B radiation on some germination and seedling characteristics of Anatolian black pine seeds. Within the scope of the study, seeds were exposed to UV-B radiation for 5, 10, 20, 30, 40, 50, and 60 min for germination experiments; and the germination speed (GS) was calculated as the ratio of the germinated seeds to the solid seeds at the end of the 7th day, whereas the germination percentage (GP) was calculated as the ratio of the germinated seeds to the solid seeds at the end of the 35th day. The seeds reserved for the seedling experiment were exposed to UV-B radiation for 1, 3, 5, and 7 h. With the measurements made at the end of the day, the seedling length (SL), the terminal bud length (TBL), the branch number (BN), the root collar diameter (RCD), the stem fresh weight (SFW), the root fresh weight (RFW), the stem dry weight (SDW) and the root dry weight (RDW), and the rooting percentage (RP) were determined. Variance analysis and Duncan test were applied to the obtained data with the help of SPSS package program. The study results revealed that the exposure time to increased UV-B radiation significantly affected all characters; the least affected character was RP, and that the most affected characters were RDW, SDW, and RCD. As a result of the study, it was found that even the applications with the lowest intensity took effect in most of the characters, that the seedling development decreased by more than 80% in terms of some characters at the end of 7-h application, and that even the decrease in the RP character, which was the least affected by the 7-h UV-B application, was above 50%.
Scientific evidence suggests forest cover across the world is gradually decreasing while the world's population is rapidly increasing. In line with this, the demand on raw wood is also increasing, ...making it impossible for the already limited natural resources to meet human needs in proportion to the increasing population size. To counter this, there is a need to increase the variety and availability of timber through genetic improvement. This has been seen in genetic improvement studies in forestry which have resulted in seed orchard establishments; however, the genetic variation in these seed orchards continues to be a topic of debate. This study aims to determine the clonal variation in chemical characteristics in a Hanonue (Kastamonu) Guenlueburun black pine (Pinus nigra Arnold. subsp. pallasiana (Lamb.) Holmboe) seed orchard. The analysis shows differences between the clones were seen at the 99.9% confidence level. Ash content, NaOH, extractive substance, and hot water solubility exhibited the highest heritability scores, according to the heritability estimates of the clones in the seed orchard. However, hemicellulose content showed an extremely low H sub(2) (0.1).
•Mediterranean pine forests are threatened by increasing warming-related aridification.•Secondary growth and mortality patterns vary between two closely related pine species.•Sustained drought stress ...predisposes Pinus nigra subsp. salzmannii to death.•Punctual drought conditions trigger death events in Pinus sylvestris.•Site conditions modulate growth patterns and drought-induced mortality events.
The long lifespan of trees makes them sensitive to climate warming, particularly when abrupt changes in climatic conditions occur and when trees are already growing near to their climatic tolerance thresholds. In many Mediterranean pine forests, drought stress induced by warmer temperatures and increased aridification compromise tree survival, causing growth decline and, eventually, triggering tree mortality. We evaluated the effect of climate on radial growth and mortality comparing dead and living trees of two pine species,Pinus sylvestrisandPinus nigrasubsp.salzmannii, in a continental Mediterranean area over a 50-year long period. We used linear mixed models and correlations to evaluate the effect of climate on basal area increment (BAI) and on ring-width indices, respectively. InP. nigra, growth was enhanced by wet and cold conditions, whilst growth increased with temperatures inP. sylvestris. A gradual BAI reduction was detected inP. nigratrees since the late 1970s, becoming more pronounced in recently dead trees. Contrarily,P. sylvestris growth did not show such decline, whilst death events in this species were linked to severe and punctual droughts. Our findings show that warming and drought stress trigger contrasting responses in functionally and phylogenetically similar tree species, and suggest climate-mediated important changes on competitive dominance in Mediterranean forests.
In this study, Anatolian black pine (ABP, Pinus nigra Arnold.) was evaluated as biosorbent for removal of crystal violet (CV) from aqueous solution. The influence of operational parameters including ...solution pH, initial CV concentration, biosorbent dosage, contact time, and temperature were studied in batch systems. The adsorption data followed well Langmuir isotherm with a maximum biosorption capacity of 12.36 mg/g. The equilibrium data were better fitted with pseudo-second-order kinetic model (R
2
˃ 0.99). Moreover, the thermodynamic parameters indicated that the CV biosorption was feasible, spontaneous, and endothermic process. This study showed that ABP (Pinus nigra Arnold.) can be used to remove CV from aqueous solutions.
Silver nanoparticles synthesized using plant extracts as reducing and capping agents showed various biological activities. In the present study, colloidal silver nanoparticle solutions were produced ...from the aqueous extracts of
and
bark. The phenolic profile of bark extracts was analyzed by liquid chromatography coupled to mass spectrometry. The synthesis of silver nanoparticles was monitored using UV-Vis spectroscopy by measuring the Surface Plasmon Resonance band. Silver nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopy, Raman spectroscopy, dynamic light scattering, scanning electron microscopy, energy dispersive X-ray and transmission electron microscopy analyses. The antimicrobial and cytogenotoxic effects of silver nanoparticles were evaluated by disk diffusion and
assays, respectively.
and
bark extract derived silver nanoparticles were spherical (mean hydrodynamic diameters of 78.48 and 77.66 nm, respectively) and well dispersed, having a narrow particle size distribution (polydispersity index values of 0.334 and 0.224, respectively) and good stability (zeta potential values of -10.8 and -14.6 mV, respectively). Silver nanoparticles showed stronger antibacterial, antifungal, and antimitotic effects than the bark extracts used for their synthesis. Silver nanoparticles obtained in the present study are promising candidates for the development of novel formulations with various therapeutic applications.
Tree barks are relevant interfaces between plants and the external environment, and can effectively retain airborne particles and elements at their surface. In this paper we have studied the ...distribution of mercury (Hg) in soils and in black pine (Pinus nigra) barks from the Mt. Amiata Hg district in southern Tuscany (Italy), where past Hg mining and present-day geothermal power plants affect local atmospheric Hg concentration, posing serious environmental concerns. Barks collected in heavily Hg-polluted areas of the district display the highest Hg concentration ever reported in literature (8.6mg/kg). In comparison, barks of the same species collected in local reference areas and near geothermal power plants show much lower (range 19–803μg/kg) concentrations; even lower concentrations are observed at a “blank” site near the city of Florence (5–98μg/kg). Results show a general decrease of Hg concentration from bark surface inwards, in accordance with a deposition of airborne Hg, with minor contribution from systemic uptake from soils. Preliminary results indicate that bark Hg concentrations are comparable with values reported for lichens in the same areas, suggesting that tree barks may represent an additional useful tool for biomonitoring of airborne Hg.
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•At the Mt. Amiata Hg district, Pinus nigra barks show high Hg concentrations.•Pinus nigra barks showed the highest Hg concentration ever reported in literature.•Tree bark is a reliable, diffuse, practical and low-cost candidate as biomonitor.
•This paper examines the effects of cropland abandonment on soil properties.•Soil recovery after cropland abandonment was slow even if afforestation was carried out.•No differences were observed ...between natural succession and afforestation.•Land cover and depth had a significant effect on the physico-chemical properties.•The impact of disturbance by afforestation techniques is difficult to discern.
Cropland abandonment and subsequent revegetation processes (due to secondary succession and afforestation practices) are global issues with important implications in Mediterranean mountain areas. Several publications have reviewed the impact of cropland abandonment and revegetation on the soil properties dynamics but, so far, limited attention has been paid to Mediterranean humid mountain areas. This paper examines six neighbouring land covers, in the Central Spanish Pyrenees to determine the effects of land covers, cropland abandonment and consequently secondary succession and afforestation practices on soil properties. For this purpose, a total of 85 samples from 6 land covers and from two soil depths were analysed. We observed that changes in soil properties after cropland abandonment were limited, even if afforestation practices were carried out, and no differences were observed between natural succession and afforestation. Land cover and depth had a significant effect on the physical and chemical variables, being larger in the uppermost 0–10cm depth. The organic and inorganic carbon and N concentration, SOC and TN stocks, CN ratio, organic matter, and bulk density showed significant differences. Afforestation improved soil properties, aggregate stability and carbon concentration and stocks when compared to neighbouring bare soils. A soil quality index −based on statistical analysis- suggested that natural forests and Pinus nigra areas developed a higher soil quality rating. Our general results also demonstrated that the impact of disturbance by afforestation techniques (microsites) is difficult to discern. The differences found with respect to the native forest appear to indicate that the afforested soils have not yet reached their maximum soil quality and maximum potential as soil organic carbon sink. As there was no difference found between the soil improvement by natural succession in comparison to afforestation, these results put the question forward which type of forest and landscape management is most appropriate to decide for the best practices after cropland abandonment for soil recovery and erosion control.
•P. sylvestris is less resistant to bark beetle attack than P. nigra.•In P. sylvestris bark beetle attack increases with tree size.•In P. nigra bark beetle attack is limited to smaller ...trees.•Interspecific variations in bark thickness and duct area explain size preferences.•Intraspecific variation in duct metrics and grow regulate tree resistance to attack.
After fire, bark beetles pose a significant threat to trees. Resin duct characteristics in trees can increase resistance to bark beetles. However, little is known about how intra- and interspecific variations in resin ducts due to tree characteristics, fire-caused tree injury and life history traits contribute to resistance. In fall 2013, a mixed-stand of Pinus sylvestris and P. nigra was underburned, with some trees subsequently attacked and killed by bark beetles (Ips sexdentatus) during the following two years. We investigated whether inter- or intraspecific differences in constitutive defenses (i.e. bark thickness, tree size and growth, resin ducts) or fire-caused tree injury could explain tree resistance to bark beetles. Beetles preferentially attacked P. sylvestris over the more fire-resistant P. nigra subsp. salzmannii. In P. nigra, attacks were limited to smaller trees, whereas the probability of mortality from I. sexdentatus increased with diameter in P. sylvestris. The decrease in bark thickness along the stem significantly affected the probability of mortality in P. sylvestris but not in P. nigra. As tree size increased, bark thickness and resin duct area investment were lower in P. sylvestris than P. nigra, suggesting reduced defences in P. sylvestris. For both species, pines that survived had faster growth, higher resin duct area, and fewer but larger ducts than pines that died after the attack. However, resin duct area and density rather than growth or fire-caused injury were better predictors of tree resistance. Moreover, in unattacked trees resin duct area increased with diameter in P. nigra. Our study showed that bark beetles attacks were tree species and size specific, but ultimately resin duct characteristics determined host colonization. Our findings suggest managers can expect higher delayed mortality from bark beetles in P. sylvestris after burning; however, actions that encourage faster growth may increase resin duct-related defences in both pine species.
Climatic warming is assumed to expand the geographic range of insect pests whose distribution is mainly constrained by low temperatures. This is the case of the pine processionary moth (Thaumetopoea ...pityocampa), which is one of the main conifer defoliators in the Mediterranean Basin. Warmer winters may lead to a northward/upward expansion of this insect, as short-term studies have shown. However, no long-term data, i.e. spanning at least one century, has been used to examine these projections. We test the hypotheses that climatic warming (i) has caused an upward shift of the pine processionary moth, and (ii) has increased the frequency of severe defoliations. We used dendrochronological methods to reconstruct defoliations over the period 1900–2006 in 14 sites spanning a wide altitudinal range (1070–1675 m) in Teruel, eastern Spain. We built local ring-width chronologies for four co-occurring pine species with different degree of susceptibility against the moth defoliations, from highly suitable or palatable species (Pinus nigra) to moderately (Pinus sylvestris, Pinus halepensis) or rarely defoliated species (Pinus pinaster). We validated the tree-ring reconstructions of outbreaks using a field record of stand defoliations spanning the period 1971–2006. Outbreaks in the most affected P. nigra stands corresponded to abrupt one- to two-year growth reductions (70–90% growth loss). Reconstructed outbreaks occurred on average every 9–14 years. The growth memory of outbreaks was weaker but lasted longer (1–6 years) than that due to droughts (1–3 years). Neither an upward expansion nor an increase in outbreak frequency was observed. Severe PPM defoliations did not increase as climate warmed, rather they were positively related to the winter North Atlantic Oscillation.
Is climate warming leading to an upwards shift of severe pine processionary moth (PPM) defoliations in Mediterranean pine forests? Field records of stand defoliation and tree-ring reconstructions of outbreaks did not support an upward shift, but allowed detecting a positive link between PPM defoliations and the winter North Atlantic Oscillation. Display omitted
•We tested if warmer winters increased pine processionary moth (PPM) defoliations.•PPM defoliation negatively impacted longer but weaker growth than drought.•Neither an upward expansion nor an increase in outbreak frequency was observed.•PPM defoliations were positively related to the winter North Atlantic Oscillation.
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