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  • Open access
  • 72 Reads
Effect of forest restoration on vegetation composition and soil characteristics in North Wollo and Waghemira Zones, Northeastern Ethiopia

As a counter measure of deforestation and forest degradation, there are many forest restoration practices with area exclosures. However, these restoration interventions are not yet scientifically evaluated weather successes or not. Thus, this study is to evaluate the impacts of forest restoration with area exclosures on vegetation and soil property changing aspects. The method followed concept of forest restoration based on selected indicators and comparing against best practices. For this purpose, three districts in three agro-ecologies were selected. In each district one exclosures, adjacent church forest and adjacent grazing land were selected. Then vegetation data were collected and analyzed by using different diversity indices. Biomass was computed by using allometric equations developed for forests of dryland tropical Africa. The soil sample were collected from the main quadrates at 5 points in three different depth and then composite. Data was analyzed by using one-way ANOVA via vegetation qualities and selected soil parameters in different land uses and agro-ecologies. The soil result was compared with critical values. There was significant difference in vegetation composition, biomass and soil attributes across land uses and agro-ecologies (p < 0.03). Exclosures showed intermediate values between Church forest and grazing land in vegetation composition, biomass and some soil attributes. Therefore, forest restoration with area exclosures is the better tool for degraded forest restoration. Further research is required to understand ecosystem services of area exclosures and trajectory of successional changes in vegetation composition and soil parameters of the area exclosures.

  • Open access
  • 178 Reads

In the territory of Bosnia and Herzegovina, uneven-aged stands of fir and beech are very important from the economic and ecological point of view. A major practical lack of information on the simple structure of stands is that they cannot be used to draw valid conclusions about the spatial distribution of woody species, the position and dimensions of trees and this is one of the bases for sustainable management of mixed and uneven-aged forests. In four mixed uneven-aged fir and beech stands and one pure fir stand on the Borja mountain, the basic elements of tree growth were measured and the data needed to determine the indicators of the spatial stand structure were determined. According to the index of aggregation of Clark and Evans, when all trees are observed, on average there is a tendency towards a uniform spatial distribution of trees in the stand. When only fir trees were selected as reference trees, it is evident that there is a tendency to group fir trees in the stand. The diameter differentiation index shows that the average tree diameter differentiation is on all sample plots. The determined values ​​of the Weber’s height competition index by stands are approximately the same, ie it can be stated that there is no significant difference between stands in terms of competition between trees when it comes to vertical structure of stands.

  • Open access
  • 128 Reads
Supercritical Extraction of Essential Oils from Dry Clove: a Technical and Economic Viability Study of a Simulated Industrial Plant

The supercritical fluid extraction (SFE) is a green methodology that allows the solvent to be easily removed by simply reducing the system’s pressure or temperature. An interesting compound to be separated through SFE is the clove’s essential oil, which contains 75.5% (m/m) of eugenol and shows many food and biomedical applications, like antibacterial and antifungal activities, and use as antioxidant, anti-inflammatory, and for asthma and allergy relief. Herein, we simulated the operation of a SFE plant with two 400 L-extractors using CO2, and performed the economic analysis based on real purchase costs from large scale exportation suppliers. Our results show that this is not only a process that results in minimum harmless emissions, consuming low amounts of utilities; but it is also an investment with excellent economic indicators, which is viable even if there are increases of 56% on clove’s purchase costs. A fixed capital expenditure (CAPEX) of 347,000 USD is required, leading to a high net present value (NPV) of 8,600,000 USD after the project’s lifetime (40 years), with a payback of 18.67 years and internal rate of return (IRR) of 7.29%.

  • Open access
  • 90 Reads
Supply Potential and Annual Availability of Timber and Forest Biomass Resources for Energy in Japan

[Aim and scope] To promote sustainable timber and forest biomass utilization, technically feasible and economically viable availability should be estimated considering forest regeneration. Therefore, this study calculated incomes and expenditures such as silvicultural and harvesting as well as stumpage prices on the Japanese cedar, cypress, pine, and larch forests using the silvicultural prescriptions set based on the regional forest plans and operation systems set based on topographic conditions such as slope angles and height differences with GIS. [Methodology] This study acquired the forest GIS for private and communal forests from prefectures and national forests from the Forestry Agency of Japan. Then, this study estimated the availability of unused materials for woody biomass power generation plants under operation with FIT at the end of June 2020 as the supply potential from the profitable subcompartments. [Novelty] Most of existing studies estimated them as a unit of municipality or a 1 km mesh whereas the present study estimated them as a subcompartment, which was an actual forest management unit. [Results] Supply potentials of used and unused materials were estimated at 65,490,336 m3/year and 13,098,067 m3/year, respectively whereas those availabilities were estimated at 31,080,672 m3/year and 6,216,134 m3/year respectively. Therefore, the rate of the availabilities to the supply potentials was 47.5%. Furthermore, the rate of the availabilities to the demands was 71.6%. Considering the subsidy rate of 100% to secure the reforestations, the availabilities met the demands in Japan as a whole. [Conclusions] The present study imply that subsidies play an essential role in the profitability of forestry operations as well as the supply of timber and forest biomass resources in Japan. The results obtained in the present study can contribute to the effective utilization of forest resources under sustainable forest management.

  • Open access
  • 55 Reads
Control of pitch canker using essential oils from medicinal and aromatic plants

Pitch canker is a tree disease caused by the fungus Fusarium circinatum (teleomorph = Gibberella circinata), known to affect mainly conifers, namely susceptible Pinus species and Douglas fir (Pseudotsuga menziesii). This fungal phytopathogen is usually transported from infected trees to susceptible healthy pines by water (e.g., rain), wind or vectored by bark beetles, and induces damping-off, resin-streaming cankers on main stems and lateral branches, shoot dieback, needle chlorosis or discoloration, cone death, and increased tree mortality. Severity of the disease is heavily dependent on the pine host and biotic and abiotic conditions, such as temperature, humidity, soil properties, insect pathogens, etc. A much higher incidence is detected at pine nurseries and plantations than on wild pine stands. In nurseries, pest management focuses on proper hygiene and phytosanitary measures that can include the use of insecticides and fungicides for direct control. Nevertheless, many active biocides have been recently withdrawn in Europe, which prompted research on natural compounds, such as essential oils (EOs). These complex mixtures of secondary metabolites are mainly comprised of terpenes and phenolic compounds, and can show very high biologic activities. The present work reviewed the available literature on EOs analyzed against Fusarium circinatum. The use of EOs in fungicidal formulations against pitch canker is still preliminary. The EOs from 62 plant species were reported against this pathogen, with over 50% of plants belonging to the Myrtaceae, Compositae and Apiaceae families. The highest activities (lowest minimum inhibitory concentrations) were obtained for the EOs of Cinnamomum verum, Cymbopogon citratus, Foeniculum vulgare, Syzygium aromaticum and Thymus vulgaris. Nevertheless, few reports detail EO chemical composition, which hinders the assessment of structure-activity correlations. A higher investment on the screening of natural compounds as eco-friendly fungicides against pitch canker is necessary to promote more sustainable disease control measures.

  • Open access
  • 92 Reads
Anatomical variability of Pinus brutia Ten. essential oils

Pinus brutia Ten., commonly known as Brutian pine, Calabrian pine or Turkish pine, is a member of the Pinaceae family, and is largely distributed throughout the eastern part of the Mediterranean, mainly in Turkey and bordering countries. Over the last years, P. brutia has increased its economic importance, due to a rapid spread over the Mediterranean Basin and for providing raw materials with high economic value, namely wood, bark, cones, extracted oleoresin and essential oils (EO). Pine EOs are obtained by hydro‐, steam‐ or dry distillation, and are mostly comprised of one to three major volatile compounds, commonly mono‐, sesqui‐ or diterpenes and phenylpropanoids. Terpenoids have high‐value commercial uses in industrial and household cleaning products, disinfectants, solvents, fragrances, medicine, and aromatherapy. Additionally, pine EOs possess significant biological activities as repellents, insecticides, antivirals, antimicrobials and antioxidants. The present work reviewed the chemical variability of EOs reported for different parts of P. brutia trees and tree products, namely needles, twigs, resins, cones, flowers, bark, sawdust and seeds. The major components reported for P. brutia EOs (≥ 20 %) were the bicyclic monoterpenes α-pinene, β-pinene and δ-3-carene, that generally comprised 50 – 90 % of EO composition. The hydrocarbon δ-3-carene showed the highest variability between samples of the same pine organ, suggesting the occurrence of chemotypes in P. brutia. The presence of α-pinene in relative amounts ≥ 20 % was reported for resin, cone, flower, sawdust and seed EOs, while β-pinene in relative amounts ≥ 20 % was reported for EOs of P. brutia needles, twigs, cones, flowers and seeds. Assessing the variability of EOs extracted from different tree parts or tree products can provide useful information for guided P. brutia EO extraction, according to its intended purpose.

  • Open access
  • 135 Reads
Forest exposure and respiratory function: a literature review

Introduction. Environmental health research has recently started to study the effects on health of well-being promoting practices based on forest exposure. This review aims to understand whether forest exposure can directly improve respiratory function.

Methods. This study was designed as a narrative literature review. PubMed, Cochrane Library and Google Scholar were searched up to April 2021 for clinical studies about changes of respiratory function induced by forest exposure and preferably measured with spirometry. Relevant evidence was summarized and critically discussed.

Results. Five studies were included in this review (three trials, an observational study and a case report). Globally, forest exposure seems to be associated with improved Forced Expiratory Volume (FEV), Peak Expiratory Flow (PEF) and Forced Vital Capacity (FVC). In most included studies, exposure time was at least 1 hour and sessions were repeated over time. Study participants were either healthy subjects or patients with respiratory diseases. Benefits were reported even in terms of inflammatory markers and were detected in children, adults and elderly individuals of both genders. The number of participants per study ranged from 1 to 65.

Discussion. Forest exposure coupled with light physical activity may result in short-term improvements of some respiratory function parameters (FEV1, FEV6, PEF, FVC). Autonomic responses to environmental stimuli and inhalation of some volatile compounds detectable in the forest air seem to directly contribute to the overall effect, which may be enhanced around waterfalls and creeks due to water nebulization. However, current scientific evidence is limited and high atmospheric levels of some plant-derived compounds, especially when reacting with air pollutants, may even worsen some respiratory conditions. Further studies on the topic are recommended to better quantify the effects size of forest-based interventions, assess long-term benefits, ascertain potential health risks and identify any moderators of the effect or confounding factors.

  • Open access
  • 104 Reads
Ayous Wood (Triplochiton scleroxylon K. Schum) physical characterisation after three different cycles of heat treatment

Thermally modified wood has an increasing interest in exteriors due to its longer service life and attractive appearance. This work evaluates the influence of the thermal modification cycle on the physical properties of ayous wood (Triplochiton scleroxylon K. Schum). Ayous planks were dried and then thermally treated for 6 hours in a conventional oven at 180°C, 190°C, and 215°C. The samples obtained were characterised for density, basic density, shrinkage and shrinkage anisotropy coefficient, and colour. Data were collected in accordance with the UNI ISO reference standards. The results of this study showed that wood density decreased by 10%, 14%, and 20%; the basic density decreased by 10%, 18%, and 22%; the tangential shrinkage decreased by 17%,29%, and 53%; the radial shrinkage decreased by 6%, 14%, and 50%; and the volumetric shrinkage decreased by 13%, 51%, and 80%; these values are referred, respectively, to 180°C, 190°C, and 215°C modification cycles. Thermo treatment is confirmed an interesting process to enhance wood stability in outdoor use.

  • Open access
  • 55 Reads
Impact of Harvested Wood Products Consumption Strategies on British Columbia’s Greenhouse Gas Emissions
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Keeping global temperature increases to below 2 ℃ will require reducing emissions and enhancing sinks and the use of forest products can contribute to both. This research quantitatively compared the greenhouse gas (GHG) emission consequences of various harvested wood products (HWPs) utilization and export strategies for British Columbia’s (BC) bioeconomy.

A carbon dynamics model, MitigAna, was developed to enable scenario-based mitigation analysis for HWPs with modules calculating substitution benefits and cascading product uses. Timber construction and wood-derived biofuels were identified as important contributors to GHG mitigation. Construction was the most climatically efficient utilization of HWPs because of its longer carbon storage and its ability to displace emissions from other emission-intensive building materials. At current harvest rates, the theoretical maximum mitigation benefit that BC forest products can contribute is 66 MtCO₂e yr⁻¹. However, BC does not currently have sufficient international market access to fully realize the mitigation potential of a construction-focused bioeconomy. Biofuel displacement markets are sufficient to provide promising substitution benefits, if the technology becomes available at a commercial scale. The best practical strategy that combines timber construction and biofuels can achieve 17.4 MtCO₂e yr⁻¹, equivalent to 30% of British Columbia's 2050 reduction target. This would involve building the same floor area as at present, but the domestic market share of timber construction would need to double at the expense of concrete and steel. Redirecting biomass feedstock from exported pulp and wood pellets, 4.4 billion L yr⁻¹ biofuels would be produced, equivalent to 50% of the energy demand in BC's transportation sector. A transformation of BC’s forest bioeconomy may help achieve both climate and socio-economic benefits. However, potential conflict exists between BC-specific benefits and maximizing the global GHG mitigation outcome. International policies and accounting rules can influence the desired global mitigation outcomes.

  • Open access
  • 72 Reads
Seasonal acclimation of PSII thermostability via pigments ratio adjustment of Norway spurce (Picea abies) in Carpathian Mountains

Norway spruce (Picea abies (L.) Karst) populations are facing increased biotic and abiotic pressure especially at lower range of their natural distribution. Elevated summer temperatures induced by global climate change might impair the physiological vitality of Norway spruce forests causing overall decrease of their tolerance to drought periods as well as increased risk from other disturbances. In this study, we analysed the ability of Norway spruce to acclimate to higher temperatures during the summer by improving the thermostability of its photosynthetic apparatus. We utilized short-term heat stress simulation with water baths followed by fast and slow kinetics of chlorophyll a fluorescence. Measurements were conducted once a month from May until September. Simultaneously, needles were sampled for pigments concentration analysis and gas exchange measurements were conducted on the same individuals. We found that Norway spruce is able to improve its PSII thermostability during summer with maximal performance after short-term heat stress occurring in July and August. This acclimation response was positively correlated with chlorophylls and carotenoids ratio which significantly differed between the observed months. Moreover, there was no significant difference in assimilation rate between during the experiment. Our results suggest that healthy trees of Norway spruce at a lower range of distribution can acclimate to higher temperatures during summer and maintain a high assimilation rate throughout vegetation season, by improving PSII thermostability via pigments ratio adjustment.