New Silvicultural Treatments for Conifer Peri-Urban Forests Having Broadleaves in the Understory - The First Application in the Peri-Urban of Xanthi in Northeastern Greece

Background and Purpose: In Greece, forest practice did not develop special silvicultural treatments for planted conifer peri-urban forests where broadleaf trees appear as natural regeneration in the understory. The aims of this study are: a) to analyze the new proposed selective silvicultural treatments for the planted peri-urban forest of Xanthi and for analogous planted conifer forests, where broadleaf trees are naturally established in the understory b) to check the research hypothesis that the new selective silvicultural treatments exhibited higher intensity in terms of the basal area of cut trees, compared to that of traditional treatments in the studied peri-urban forest. Materials and Methods: In the traditional treatments, in the pine overstory cuttings, apart from the dead trees, mainly the malformed, damaged, suppressed and intermediate trees were cut. In the lower stories, the goal of the thinning was the more or less uniform distribution of broadleaf trees. In the proposed selective treatments, the main aim of pine cuttings is to release the broadleaf formations growing in the lower stories, while the treatments of the broadleaf trees will be a form of “positive selection” thinning. Plots were established in areas where the two types of treatments were going to be applied. In each plot, tree measurements and a classification of living trees into crown classes took place. After the application of the treatments the characteristics of cut trees were recorded. Results: In the established plots, before the cuttings (and thinning), total basal area was not statistically significantly different between the two types of treatments. In selective treatments, the basal area of all cut trees was statistically significantly higher than that of the results of traditional treatments. In the broadleaf cut trees there were statistical differences in the ratios of dominant, intermediate and suppressed trees between the two silvicultural approaches. Conclusions: The research hypothesis was verified. The intensity of treatments in terms of the basal area of cut trees was higher in the selective approach, compared to the traditional treatments in the Xanthi peri-urban forest. However, the overstory cutting intensity of the selective treatments depends on the spatial distributions and densities of broadleaved and conifer trees. In the broadleaf trees, the different objectives of the two types of treatments resulted in thinning with different qualitative characteristics. The proposed silvicultural treatments will accelerate the conversion of peri-urban conifer forests having an understory of broadleaf trees into broadleaved forests, or into mixed forests of conifers and broadleaf trees

Single-entry volume table for Pinus brutia in a planted peri-urban forest

Brutia pine is a Mediterranean tree species of high ecological value, widely planted for soil protection, windbreaks and timber, both in its native area and elsewhere in the Mediterranean region. However, there is not yet enough information relating its growth dynamics and yield. The aim of this study was to evaluate the volume of Pinus brutia in a planted peri-urban forest (reforested area) in Greece. A single-entry, individual tree volume model has been developed using data from 18 permanent experimental plots, in the context of a research project regarding recovery of degraded coniferous forests

Ecophysiology of seedlings of three Mediterranean pine species in contrasting light regimes

Seasonal dynamics of net photosynthesis (Anet) in 2-year-old seedlings of Pinus brutia Ten., Pinus pinea L. and Pinus pinaster Ait. were investigated. Seedlings were grown in the field in two light regimes: sun (ambient light) and shade (25% of photosynthetically active radiation (PAR)). Repeated measures analyses over a 12-month period showed that Anet varied significantly among species and from season to season. Maximum Anet in sun-acclimated seedlings was low in winter (yet remained positive) and peaked during summer. Maximum Anet was observed in June in P. pinea (12 μmol m–2 s–1), July in P. pinaster (23 μmol m–2 s–1) and August in P. brutia (20 μmol m–2 s–1). Photosynthetic light response curves saturated at a PAR of 200–300 μmol m–2 s–1 in winter and in shade-acclimated seedlings in summer. Net photosynthesis in sun-acclimated seedlings did not saturate at PAR up to 1900 μmol m–2 s–1 in P. brutia and P. pinaster. Minimum air temperature of the preceding night was apparently one of the main factors controlling Anet during the day. In shade-acclimated seedlings, photosynthetic rates were reduced by 50% in P. brutia and P. pinaster and by 20% in P. pinea compared with those in sun-acclimated seedlings. Stomatal conductance was generally lower in shaded seedlings than in seedlings grown in the sun, except on days with a high vapor pressure deficit. Total chlorophyll concentration per unit leaf area, specific leaf area (SLA) and height significantly increased in P. pinea in response to shade, but not in P. pinaster or P. brutia. In response to shade, P. brutia showed a significant increase in total chlorophyll concentration but not SLA. Photosynthetic and growth data indicate that P. pinaster and P. brutia are more light-demanding than P. pinea

Ecophysiology of seedlings of three Mediterranean pine species in contrasting light regimes

Seasonal dynamics of net photosynthesis (Anet) in 2-year-old seedlings of Pinus brutia Ten., Pinus pinea L. and Pinus pinaster Ait. were investigated. Seedlings were grown in the field in two light regimes: sun (ambient light) and shade (25% of photosynthetically active radiation (PAR)). Repeated measures analyses over a 12-month period showed that Anet varied significantly among species and from season to season. Maximum Anet in sun-acclimated seedlings was low in winter (yet remained positive) and peaked during summer. Maximum Anet was observed in June in P. pinea (12 μmol m–2 s–1), July in P. pinaster (23 μmol m–2 s–1) and August in P. brutia (20 μmol m–2 s–1). Photosynthetic light response curves saturated at a PAR of 200–300 μmol m–2 s–1 in winter and in shade-acclimated seedlings in summer. Net photosynthesis in sun-acclimated seedlings did not saturate at PAR up to 1900 μmol m–2 s–1 in P. brutia and P. pinaster. Minimum air temperature of the preceding night was apparently one of the main factors controlling Anet during the day. In shade-acclimated seedlings, photosynthetic rates were reduced by 50% in P. brutia and P. pinaster and by 20% in P. pinea compared with those in sun-acclimated seedlings. Stomatal conductance was generally lower in shaded seedlings than in seedlings grown in the sun, except on days with a high vapor pressure deficit. Total chlorophyll concentration per unit leaf area, specific leaf area (SLA) and height significantly increased in P. pinea in response to shade, but not in P. pinaster or P. brutia. In response to shade, P. brutia showed a significant increase in total chlorophyll concentration but not SLA. Photosynthetic and growth data indicate that P. pinaster and P. brutia are more light-demanding than P. pinea

EFFECTS OF COLD STRATIFICATION AND GA3 ON GERMINATION OF ARBUTUS UNEDO SEEDS OF THREE PROVENANCES

Background: Arbutus unedo is a valuable Mediterranean shrub as an ornamental plant as well as fruit tree. Fresh fruits of A. unedo are a good source of antioxidants, of vitamins C, E and carotenoids and also are characterized by the high content of mineral elements. Materials and Methods: The effects of gibberellic acid (GA3) and cold stratification (CS) on seed germination performance were investigated in A. unedo seeds collected from three provenances in the Northern part of Greece. Seeds of each provenance were soaked in solutions of GA3 (500, 1000 or 2000 ppm) for 24 h and subsequently were subjected to CS at 3 – 5ºC for 0, 1, 2, and 3 months. Results: Non-stratified seeds of the three A. unedo provenances which were not treated with GA3 solutions exhibited very low germination. However, seed germination was significantly improved after a one-month period of CS. Similarly, the non-stratified seeds of all three provenances became non-dormant after the treatment with 2000 ppm GA3 and they germinated at high percentages. However, in untreated seeds with GA3, after a one-month CS period the seeds of the Pieria provenance exhibited higher germination percentage than that of Rodopi provenance seeds. Furthermore, in non-stratified seeds, the Pieria provenance seeds treated with GA3 germinated at higher percentages and more rapidly than those of the other two provenances. Conclusion: The results indicated that untreated seeds exhibited very low germination at 20/25ºC. However, in all three provenances seed germinability was significantly improved by a one-month period of CS or treatment of seeds with 2000 pp

Carbon sequestration and soil nitrogen enrichment in Robinia pseudoacacia L. post-mining restoration plantations

Robinia pseudoacacia L. (black locust) has been extensively used for restoring degraded lands, following anthropogenic interventions like coal mining. Here we have addressed the contribution of black locust restoration plantations, established on overburden post-mining material, to carbon storage and to soil nitrogen enrichment at the largest lignite center in Greece. Carbon stocks and fluxes in all pools of the ecosystem, as well as the foliar nitrogen resorption efficiency and soil N stocks were quantified and the effect of plantations’ age was tested. The young age of the plantations (4–24 years) resulted in a relatively low total ecosystem C stock (56.7 t ha−1), which was partitioned among the different pools in the following order: above-ground biomass (50%) > black locust-derived SOC (24%) > coarse roots (14%) > deadwood (6%) > forest floor (5%) > fine roots (less than 1%). Litterfall started early in the growing season and together with fine roots that had a turnover rate of 0.62 yr−1, fueled soil organic carbon. SOC accrual, referring to the accumulation of SOC derived by black locust, declined with age. However, further SOC accumulation is expected, based on the potential SOC storage capacity of soil at the area. C stocks in above- and below-ground biomass increased linearly with age. The same response was observed for soil N stock and NRE, indicating that despite the N2-fixing capacity of black locust, there was still a poor pedospheric N supply and a need for efficient N cycling. Overall, the studied restoration plantations have a considerable contribution to C and N accumulation at the degraded post-mining sites. These positive effects are expected to further increase at least until the plantations reach maturity

Effects of desiccation and freezing on vitality and field performance of broadleaved tree species

Seedlings of Acer pseudoplatanus L., Fraxinus ornus L. and Castanea sativa Miller., were exposed to desiccating conditions (15 oC, 50% RH, air movement 0.3 m s$^{-1}$, photosynthetic active radiation 350 $\mu$mol m$^{-2}$ s$^{-1}$) and freezing (-5 oC, darkness). The effect of stress factors on seedling quality was assessed using root electrolyte leakage, water potential and moisture content of fine roots. After treatments, seedlings were outplanted in a field site. The effects of desiccation and freezing on planting stock quality and field performance varied and depended upon the length of exposure and species. Root electrolyte leakage values were significantly related to field performance rates of seedlings exposed to both stress factors. Root moisture content and root water potential were related to survival only in the case of desiccation treatment.Effets du dessèchement et de la congélation sur la vitalité et la performance des plants d'espèces arborées platyphylles. Des plants d'Acer pseudoplatanus L., Fraxinus ornus L. et Castanea sativa Miller, ont été soumis à des traitements conditionnés contrôlés de dessèchement (15 oC, 50 % HR, mouvement d'air 0.3 m s$^{-1}$, PAR 350 $\mu$mol m$^{-2}$ s$^{-1}$) et de congélation (à -5 oC, dans l'obscurité). Les effets de ces facteurs de stress sur la qualité des plants ont été établis par la mesure de la perte relative en électrolyte, du potentiel hydrique et de la teneur en eau des racines fines. Après ces traitements, les plants ont été installés en plantation. Les effets du dessèchement et de la congélation sur la qualité et la performance des plants varient et dépendent du temps d'exposition et des espèces. Les valeurs de perte relative en électrolyte racinaire sont fortement corrélées aux niveaux des performances des plants exposés aux facteurs de stress. La teneur en eau des racines et le potentiel hydrique sont reliés à la survie seulement dans le cas du traitement de dessèchement

SITE INFLUENCE ON THE SUCCESS OF REFORESTATION AND ON THE ECOPHYSIOLOGICAL CONDITION OF TREES OF THE KEDRINOS HILL THESSALONIKI

THE PRESENT WORK INCLUDES THE STATHMOLOGICAL, THE ECOPHYSIOLOGICAL RESEARCH ANDTHE RESEARCH ON GROWTH AND BIOCHEMICAL PARAMETERS OF THE ARTIFICIAL FOREST OF KEDRINOS HILL OF THESSALONIKI. FOUR QUALITY SITES HAVE BEEN DISTINGUISHED FOR PINUS BRUTIA WITH THE PHYSIOGRAPHIC DATA. FOR THIS PURPOSE PLANT TAKINGS HAVE BEEN TAKEN PLACE. THE PROCESS OF PLANT TAKINGS HAVE BEEN DONE BY COMPUTER. ON THEDISTINGUISHED SITE QUALITIES HAVE BEEN TAKEN PROFILE SOIL AND SOIL ANALYSES. THE AVAILABLE SOIL MOISTURE HAS BEEN ALSO DEFINED. THE HEIGHT CURVES AND THE INCREMENTAL CURVES FOR ALL QUALITY SITES WERE FORMED. BY THE TAKING OF SAMPLING AREAS HAS BEEN ESTIMATED THE MEAN HEIGHT, THE MEAN DIAMETER AND THE CIRCULAR AREA. (SHORTENED)Η ΠΑΡΟΥΣΑ ΕΡΓΑΣΙΑ ΠΕΡΙΛΑΜΒΑΝΕΙ ΤΗ ΣΤΑΘΜΟΛΟΓΙΚΗ, ΤΗΝ ΟΙΚΟΦΥΣΙΟΛΟΓΙΚΗ ΕΡΕΥΝΑ ΚΑΙ ΤΗΝ ΕΡΕΥΝΑ ΤΩΝ ΑΥΞΗΤΙΚΩΝ ΚΑΙ ΒΙΟΧΗΜΙΚΩΝ ΠΑΡΑΜΕΤΡΩΝ ΤΟΥ ΤΕΧΝΗΤΟΥ ΔΑΣΟΥΣ ΤΟΥ ΚΕΔΡΗΝΟΥ ΛΟΦΟΥ ΘΕΣΣΑΛΟΝΙΚΗΣ. ΔΙΑΚΡΙΘΗΚΑΝ ΜΕ ΤΗΝ ΒΟΗΘΕΙΑ ΟΜΑΔΩΝ ΦΥΤΟΔΕΙΚΤΩΝ, ΕΔΑΦΙΚΩΝ ΑΝΑΛΥΣΕΩΝ ΚΑΙ ΤΩΝ ΦΥΣΙΟΓΡΑΦΙΚΩΝ ΔΕΔΟΜΕΝΩΝ ΤΕΣΣΕΡΙΣ ΠΟΙΟΤΗΤΕΣ ΤΟΠΟΥ ΓΙΑ ΤΗΝ ΤΡΑΧΕΙΑ ΠΕΥΚΗ (PINUS BRUTIA). ΓΙΑ ΤΟΝ ΣΚΟΠΟ ΑΥΤΟ ΕΓΙΝΑΝ ΦΥΤΟΛΗΨΙΕΣ. Η ΕΠΕΞΕΡΓΑΣΙΑΤΩΝ ΦΥΤΟΛΗΨΙΩΝ ΕΓΙΝΕ ΜΕ ΗΛΕΚΤΡΟΝΙΚΟ ΥΠΟΛΟΓΙΣΤΗ. ΣΤΙΣ ΔΙΑΚΡΙΘΕΝΤΕΣ ΠΟΙΟΤΗΤΕΣ ΤΟΠΟΥ ΕΓΙΝΑΝ ΕΔΑΦΟΤΟΜΕΣ ΚΑΙ ΕΔΑΦΙΚΕΣ ΑΝΑΛΥΣΕΙΣ ΚΑΙ ΠΡΟΣΔΙΟΡΙΣΤΗΚΕ Η ΔΙΑΘΕΣΙΜΗ ΕΔΑΦΙΚΗ ΥΓΡΑΣΙΑ. ΣΧΗΜΑΤΙΣΤΗΚΑΝ ΟΙ ΚΑΜΠΥΛΕΣ ΥΨΟΥΣ ΚΑΙ ΟΙ ΠΡΟΣΑΥΞΗΤΙΚΕΣ ΓΙΑ ΟΛΕΣ ΤΙΣ ΠΟΙΟΤΗΤΕΣ ΤΟΠΟΥ. ΜΕ ΤΗΝ ΛΗΨΗ ΔΕΙΓΜΑΤΟΛΗΠΤΙΚΩΝ ΕΠΙΦΑΝΕΙΩΝ ΕΚΤΙΜΗΘΗΚΕ ΤΟ ΜΕΣΟ ΥΨΟΣ, Η ΜΕΣΗ ΔΙΑΜΕΤΡΟΣ ΚΑΙ Η ΚΥΚΛΙΚΗ ΕΠΙΦΑΝΕΙΑ . (ΠΕΡΙΚΟΠΗ

Effects of continuous spectrum LEDs used in indoor cultivation of two coniferous species Pinus sylvestris L. and Abies borisii-regis Mattf

The effects of four different continuous spectrum LED light qualities on the growth characteristics of Pinus sylvestris L. (PS) and Abies borisii-regis Mattf. (AB) seedlings were studied. The seedlings were exposed for 35 days inside growth chambers to G2 (high in red and far-red), AP67 (high in blue and far-red), AP67-ARCH (high in green), and NS2 (high in blue including a small percentage in the UV area) LEDs, as well as fluorescent light (FL) as Control. Each species showed a unique light-adapted response. G2 treatment stimulated needle formation of PS seedlings, while AB seedlings were unaffected. Hypocotyl elongation was promoted by FL; however, LEDs resulted in compact plants with greater root development, especially under the AP67-ARCH and AP67 spectra for PS and AB, respectively. In PS, AP67-ARCH and G2 significantly increased dry weight, while AB was affected significantly by AP67 and NS2. Furthermore, root growth potential of both species was better after LED pre-cultivation than the FL. Therefore, the use of continuous spectrum LEDs can enhance desirable quality characteristics of seedlings, which may be advantageous in large scale seedling production for reforestation

Artificial LED lighting enhances growth characteristics and total phenolic content of Ocimum basilicum, but variably affects transplant success

The morphological and phytochemical characteristics of two Ocimum basilicum cultivars (Lettuce Leaf, and Red Rubin-mountain Athos hybrid) under artificial lighting were investigated. Four LED light treatments [AP673L (high red and high red:far-red), G2 (high red and low red:far-red), AP67 (moderate blue and red and low red:far-red), and NS1 (high blue and green, high red:far-red and 1% ultraviolet)] with different colors mixing UV, blue, green, red and far-red, and fluorescent tubes (FL, high blue, green and red:far-red) as Control were used in the growth chambers for 28 days under PPFD of 200±20μmolm-2s-1 for all treatments at plant height. G2, Control and AP67 treatments for Lettuce Leaf, and G2 for Red Rubin hybrid had higher growth rate. Roots of Lettuce Leaf were significantly longer under AP673L compared to NS1, while Red Rubin hybrid showed no significant differences. Total biomass was significantly greater under NS1, AP67 and G2 compared to the Control, for both cultivars. For both Lettuce Leaf and Red Rubin hybrid, root:shoot ratio (R/S) was favored under NS1, whereas the Control had the lowest impact. Leaf area of both cultivars was greater under the Control. Root growth capacity evaluation was also assessed. Seedlings of Lettuce Leaf cultivated under the effect of the Control and AP673L, and seedlings of Red Rubin hybrid grown under AP673L (mainly) quickly developed new root system. This could offer the advantage of fast exploitation of larger soil volume after transplanting. Total phenolic content of Lettuce Leaf was significantly higher under NS1 compared to the rest of the treatments, while in Red Rubin hybrid, NS1 had significantly higher total phenolic content compared to the Control and G2. Our study demonstrates that LEDs variably affected growth characteristics and increased total phenolic content compared to conventional fluorescent light for these two O. basilicum cultivars.</p