The Effects of Ash and Black Carbon (Biochar) on Germination of Different Tree Species

Forest fires generate large amounts of ash and biochar, or black carbon (BC), that cover the soil surface, interacting with the soil’s constituents and its seedbank. This study concerns reproductive ecology assessments supported by molecular characterisation to improve our understanding of the effects of fire and fire residues on the germination behaviour of 12 arboreal species with a wide geographic distribution. For this purpose, we analysed the effects of three ash and one BC concentration on the germination of Acacia dealbata Link, A. longifolia (Andrews) Willd., A. mearnsii De Wild., A. melanoxylon R. Br., Pinus nigra Arnold, P. pinaster Aiton, P. radiata D. Don, P. sylvestris L., Quercus ilex L., Q. pyrenaica Willd., Q. robur L., and Q. rubra L. Each tree species was exposed to ash and BC created from its foliage or twigs (except for Q. rubra, which was exposed to ash and BC of Ulex europaeus L.). We monitored germination percentage, the T50 parameter, and tracked the development of germination over time (up to 1 yr). The BC of A. dealbata, P. pinaster, and Q. robur was analysed by pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS) to assess the molecular composition. In six species, ash inhibited the germination, while in another five species, germination was not affected by ash or by BC. In Q. rubra, ash and BC stimulated its germination. This stimulating effect of the BC on Q. rubra is likely to be related to the chemical composition of the ash and BC obtained from Ulex feedstock. The BC of U. europaeus has a very different molecular composition than the other BC samples analysed, which, together with other factors, probably allowed for its germination stimulating effects.This study was carried out within the Project 10MDS200007PR, financed by the Xunta de Galicia; the Project AGL2013-48189-C2-2-R, financed by the Ministerio de Economía y Competitividad, Spain; and FEDERS

Ecology and conservation status of Taxus baccata population in NE Chalkidiki, northern Greece

Taxus baccata L. is a rare species threatenedwith extinction in Greece, as in other parts of Europe. This paper deals with the ecological status of the species in the area of NE Chalkidiki northern Greece, where the species appears in one of the greatest populations of the country. Site, standand yew population characteristics were studied in the area that species occupies. Eleven sample plots were marked, and on each plot, the height and diameter at breast height (DBH) were measured for all yew trees, as well as for all the individuals of the rest tree species, with diameter at breast height greater than 4 cm. Tree vitality of all trees was also estimated according to IUFRO classification. Yew radial growth was studied using tree-ring analysis. Tree natural regeneration was investigated within subplots of different dimensions and according to two height classes. Results showed that yew population occurs in stands dominated by beech, presenting a mean density of 301 trees per hectare, with a total population of 430 trees with DBH above 4 cm. It forms the secondary stand, and dominates in the stand understorey, accompanied with Fagus sylvatica and Ilex aquifolium, while it appears rarely in the overstorey. Yew tree vitality was foundto be quite high, and significantly higher than that of beech. Radial growth of the sampled trees follows a slow and constant annual increment gradually decreasing by tree age. Yew natural regeneration was foundto be relatively low, 1341.8 individuals (seedlings and saplings up to 1 m) per hectare. Management and in situ conservation of the species in the area should focus on species protection measures, andon specific silvicultural treatments for creating favourable conditions for species growth

First results on early post-fire succession in an Abies cephalonica forest (Parnitha National Park, Greece)

Due to climate changes, the interest in the post-fire recovery of forest communities not adapted to wildfires, such as Greek fir (Abies cephalonica) forests, has increased. In this study, the post-fire recovery of the burned A. cephalonica forest of Parnitha National Park (central Greece) was investigated after a stand-replacing fire occurred in summer 2007, as well as the performance of A. cephalonica plantings in the post-fire conditions. The research focused on the estimation of the A. cephalonica stand reproductive capacity without fire, the evaluation of the post-fire regeneration of the burned stands, and the monitoring of the plantations performance after the fire in the area. Then, based on the field and laboratory data, the post-fire recovery process of A. cephalonica was evaluated by application of a simplified form of the comprehensive causal framework for ecological succession estimation in open site, developed by Pickett et al. (1987), adapted to the study conditions. According to the findings of the study, stand seed crop without fire was high, while seed quality was found extremely low. In the burned area, no A. cephalonica seedling recruitment was observed during the three years after the fire. A. cephalonica plantings exhibited a medium overall survival rate (65.3%), while seedlings growth was very slow. Thus, we can suppose that an ecological succession process may occur in the burned area, if no human interventions applied, and species adapted to wildfires (mainly shrubs and herbaceous) will dominate in the area. However, planting of A. cephalonica seedlings could contribute to the species participation in the post-fire communities

Seed and cone diversity and seed germination of Pinus pinea in Strofylia Site of the Natura 2000 Network

Variation in cone size, seed number per cone, seed potential, seed efficiency, seed morphology and seed germination behavior of Pinus pinea and its relation to stand conditions was analyzed. Data were collected from P. pinea forest in Strofylia, southern Greece, a forest that belongs to the Natura 2000 European network and the RAMSAR convention and is characterized by the absence of regeneration for many decades. The pine stands found in the area were distinguished into five categories according to a previous study and our observations, regarding stand age, canopy cover and the degree of stress by human pressure. The categories are: (I) young artificial, (II) closed-mature, (III) open-mature, (IV) over-mature stands and (V) highly degraded stands. Cones were collected from all stand types and their morphological characteristics as well as their seed production were measured. Seeds were extracted from the collected cones, measured and their germination behavior was tested. The findings showed that the over-mature and the high degraded stands and to a lesser extent, the closed-mature stands, produced significantly smaller cones with a lower seed potential, a lower number of filled seeds per cone, a greater number of not fully developed seeds and reduced seed morphological characteristics than the young and open-mature stands. However, the seed germination behavior of fully developed seeds was only slightly affected by the stand type. © 2008 Springer Science+Business Media B.V

Variation in acorn traits among natural populations of Quercus alnifolia, an endangered species in Cyprus

Quercus alnifolia is an endemic species in Cyprus, and it is rated as Vulnerable (VU) in the Red List of Oaks. Although Q. alnifolia has a great ecological importance, there are only few studies about this species. In this work we have studied the natural variability of this species by analyzing acorn dimensions, acorn mass, length of embryo, moisture content of acorns and seed germinability among the seven acorn provenances, collected in Cyprus. We also determined the seeds responses to drying. Germination trials were also carried out, and differences in seed germination among populations were examined. Rate of water loss and its effect on seed germination was also estimated by application of specific desiccation treatments. The results showed that acorn characteristics significantly differed between the populations, following a general trend to reduce their dimensions and mass with the altitude increase. Seed germination was high for all studied populations, and germination behaviour was similar for all populations. Desiccation of acorns below 35% resulted in a great reduction of seed germination capacity

Masting and regeneration dynamics of Abies cephalonica, the Greek endemic silver fir

Masting and regeneration dynamics were investigated in a long-term perspective using Abies cephalonica as a study tree species. Extensive fieldwork was implemented in Parnitha National Park, Greece, following a large-scale wildfire. Annual cone production was monitored for a 5-year period in 130 tagged trees, in 13 plots with 10 individuals each, established both within the unburned part of the forest and in surviving fragments of the burned area. In the most recent masting year, a high percentage (88%) of cone-bearing trees was recorded, along with a sizeable, average cone production (40.8 cones per tree). In the intermediate, non-masting years, the corresponding values ranged from 2% to 55% and 0.08 to 5.9 cones per tree, respectively. The reproduction process is affected by both tree density and regional climatic conditions, in particular temperature during spring of the maturation year and precipitation during spring and summer of the previous year. For the first time according to our knowledge, natural regeneration was recorded for a 4-year period, in 13 permanent transects within the monitoring plots, in relation with a masting event and the additional implications of a preceding wildfire. Highest mean density of seedlings and saplings (11.4 per m2) was observed during the first spring after masting. In the non-masting years, the corresponding value ranged from 2.1 to 2.9 per m2. Seedling survival during their first summer was considerable (30-76%) but stabilized afterwards (1-3 years) at a lower level (10-20%). The particular post-masting seedling flush was followed by an extremely high mortality rate (88.6%) and cannot represent a major recruitment event. © 2019 Cambridge University Press

Interannual variability of germination and cone/seed morphometric characteristics in the endemic Grecian fir (Abies cephalonica) over an 8-year-long study

Abies cephalonica cone and seed morphometric characteristics as well as seed germination behaviour were investigated during an 8-year-long diachronic study (2007-2015). The research was carried out in Parnitha National Park, in the part of this Greek endemic, silver fir population that was spared from an unprecedented wildfire (2007). A statistically significant interannual and among-tree variation of cone traits has been identified, except for cone diameter. Cone length is correlated to the number of seeds per cone, while the percentage of empty seeds has been consistently high, with extreme values of 29.3 and 81.8% in a masting (2015) and lean crop (2009) year, respectively. There is also a considerable proportion of dead (including infected) and non-germinated seeds, and the eventual germinable fraction is well below 25% with spikes in masting years (39.4 and 60.9% in 2010 and 2015, respectively). Untreated seeds have been tested at a wide range of constant and alternating temperatures and germination is completed within 4-5 weeks at T ≥ 15°C and ca 15 weeks at 5-10°C. A chilling pretreatment of 4-8 weeks (at 2-4°C) concludes germination at 15-20°C within 2 weeks. A significant white light requirement has been observed for untreated seeds at 15-20°C, while germination was light indifferent at lower or higher temperatures. Data obtained in this study confirm the present, field seed germination during springtime; we may also predict an earlier germination (late autumn to mid-winter) in forest gaps, under the predicted, warmer conditions in the future. © Copyright Cambridge University Press 2017

A Sustainable Strategy for Reforestation and Restoration of Burnt Natural Areas in Mediterranean Regions: A Case Study from Greece

Greece, along with most of the countries in the Mediterranean basin, is historically linked with forest fires. Wildfires have always occurred, are happening, and will continue to occur, causing serious problems regarding the sustainability of natural resources. Their frequency, however, has shown a noticeable increase during the last decades; according to the most recent projections, the broader Mediterranean region will face significant challenges in the future within the context of climate change. Despite the historical experience of forest fires in Greece, a standardized and up-to-date system for identifying and prioritizing burnt areas, in relation to their restoration needs, has not yet been developed and adopted. In this paper, a systematic methodological approach for decision-making regarding the identification and prioritization of active restoration/reforestation of burnt areas is proposed. This approach is based on critical parameters, such as the regeneration potential of the affected forest species, the “fire history”, and the slope of the affected areas. The proposed methodological approach can be applied in all burnt natural areas in the country in the future, as well as in other areas of the Mediterranean region. The fire impact on Natura 2000 sites is also assessed to highlight the importance of restoration and conservation needs in protected areas. The results from case studies are presented, and future steps and policy recommendations for the post-fire management of natural ecosystems are discussed to enable the sustainable management of forest resources in the burnt areas