Network Meta-Analysis of Metabolic Effects of Olive-Oil in Humans Shows the Importance of Olive Oil Consumption With Moderate Polyphenol Levels as Part of the Mediterranean Diet

The beneficial role of olive oil consumption is nowadays widely recognized. However, it is not clear whether its health effects are due to the presence of monounsaturated lipids and/or to the antioxidant fraction of microconstituents present in olive oil. The aim of the present study was to analyze the exact role of olive oil in the modification of metabolic factors (glucose and circulating lipids) and explore the role of its antioxidant polyphenols. In the present work, we have performed a network meta-analysis of 30 human intervention studies, considering direct and indirect interactions and impact of each constituent. Interestingly, we show that the impact of olive oil on glucose, triglycerides, and LDL-cholesterol is mediated through an adherence to the Mediterranean diet, with the only notable effect of olive oil polyphenols being the increase of HDL-cholesterol, and the amelioration of the antioxidant and inflammatory status of the subjects. Additionally, we report for the first time that lower antioxidant polyphenol levels may be sufficient for the beneficial effects of olive oil, while we show that the lipid fraction of olive oil may be responsible for some of its beneficial actions. In all parameters examined the beneficial effect of olive oil was more pronounced in subjects with an established metabolic syndrome or other chronic conditions/diseases. In conclusion, all these findings provide new knowledge that could lead to re-establishment of the role of olive oil in human nutrition

Micrometeorology and water availability of a deciduous forest

This study is a contribution το understanding the ways and mechanisms with which tree-stands interact with the environment, forming the micrometeorological regime of the soil-plant-atmosphere system, along with expanding knowledge on the mass and energy exchanges between vegetation and the atmosphere, under the Mediterranean climate conditions. The thesis is focused on the investigation of the micrometeorology of a natural deciduous ecosystem, compared to the weather conditions above, the specification of the interactions between the micrometeorological parameters on a diurnal, seasonal and annual basis (combined with the phenological phases of the vegetation), the differentiation of the micrometeorological regime following a forest fire or logging, the study of the weather effects on the vegetation water requirements and the relationship between water consumption and production, the evaluation of defense and adaptation mechanisms of Mediterranean ecosystems against extreme weather and climate conditions, the evaluation of the forest contribution on CO₂ absorption, the study of radiation quantity, quality and distribution in and use by the canopy and finally the study of the ecosystem-environment energy exchanges. Research was accomplished in a selected natural deciduous oak forest within the region of Corinth, S. Greece, where a well equipped micrometeorological station was placed. The data covers the period 1999-2006 with some missing gaps. Simple meteorological data were taken in 6 heights over the soil surface and in 4 depths below. The Eddy covariance technique was also used. Although the deciduous ecosystem develops under rather adverse (xerothermic) climatic conditions seems to be quite productive. It has relatively short water needs and developed adaptation (survival) mechanisms, such as the use of morning dew as an additional water source in summer, the root system development for deeper soil water use, the biomass development over a water holding clay soil layer, the evapotranspiration and photosynthesis reduction under extremely dry conditions via stomatal closure, the development of a relatively small leaf area, the relatively inefficient use of the absorbed by leaves radiation and finally the existence of a thick layer of dead leaves covering the forest floor and protecting the root system against thermal and water stress.Σκοπός της ερευνητικής αυτής προσπάθειας είναι η διερεύνηση των μηχανισμών με τους οποίους η δενδρώδης βλάστηση αλληλεπιδρά με το περιβάλλον, διαμορφώνοντας το μικρομετεωρολογικό καθεστώς στο σύστημα έδαφος-φυτό-ατμόσφαιρα και η μελέτη των ανταλλαγών μάζας και ενέργειας μεταξύ φυλλοβόλων οικοσυστημάτων και ατμόσφαιρας, κάτω από τις ιδιαίτερες μεσογειακές συνθήκες. Αναλυτικότερα, επιχειρείται η διερεύνηση των μικρομετεωρολογικών συνθηκών και των διαφοροποιήσεων τους με τις καιρικές μεταβολές, μέσα σε ένα φυσικό, δενδρώδες, φυλλοβόλο οικοσύστημα και στο έδαφος, ο εντοπισμός των αλληλεπιδράσεων μεταξύ των μικρομετεωρολογικών παραμέτρων και η μελέτη των χρονικών μεταβολών τους σε κλίμακα ημέρας, εποχής και έτους, αλλά και ο εντοπισμός των αλλαγών μετά από ανθρωπογενείς παρεμβάσεις (υλοτομία και έρπουσα πυρκαγιά). Μελετάται επίσης, η επίδραση των καιρικών συνθηκών στην υδατοκατανάλωση και στην παραγωγή, αξιολογείται η παραγωγικότητα σε σχέση με τη διαθεσιμότητα νερού, εντοπίζονται οι μηχανισμοί άμυνας και προσαρμογής των μεσογειακών οικοσυστημάτων στις δυσμενείς μετεωρολογικές συνθήκες, ποσοτικοποιείται η συμβολή του δάσους στην απορρόφηση CO₂ και διερευνάται ποσοτικά και ποιοτικά η αξιοποίηση, κατανομή και διαθεσιμότητα της ηλιακής ακτινοβολίας για φωτοσύνθεση. Τέλος μελετώνται οι ροές ενέργειας μεταξύ οικοσυστήματος και περιβάλλοντος. Η έρευνα πραγματοποιήθηκε σε αισθητικό δρυοδάσος της Κορινθίας (Μογγοστός), με εφαρμογή της μεθοδολογίας Eddy covariance, μετρήσεις ατμοσφαιρικών και εδαφικών παραμέτρων σε 6 ύψη και 4 βάθη και λήψη βιομετρικών στοιχείων, κατά την περίοδο 1999- 2006. Από τα αποτελέσματα προκύπτει ότι το οικοσύστημα αναπτύσσεται σε οριακές κλιματικές συνθήκες όμως ανταποκρίνεται ικανοποιητικά όσον αφορά την παραγωγικότητα του. Έχει σχετικά μικρές υδατικές ανάγκες και σε περιόδους έντονης θερμικής καταπόνησης, που συνοδεύονται από περιορισμένη διαθεσιμότητα νερού, έχει αναπτύξει προσαρμοστικούς μηχανισμούς επιβίωσης, όπως η αξιοποίηση της δρόσου τα πρωινά του καλοκαιριού, η ανάπτυξη βαθιού ριζικού συστήματος, η ανάπτυξη πάνω από αργιλικό εδαφικό στρώμα υψηλής υδατοσυγκράτησης, ο περιορισμός της εξατμισοδιαπνοής και η αναστολή της ανάπτυξης σε έντονες ξηροθερμικές συνθήκες, η μικρή φυλλική επιφάνεια, η σχετικά μικρή αξιοποίηση της έντονα απορροφούμενης από το φύλλωμα ηλιακής ακτινοβολίας και η ύπαρξη στρώσης μεγάλου πάχους βραδέως αποδομούμενης νεκρής φυλλάδας, που προστατεύει το ριζόστρωμα από θερμική και υδατική καταπόνηση

Growth Response of Endemic Black Pine Trees to Meteorological Variations and Drought Episodes in a Mediterranean Region

Weather variations affect natural ecosystems, while in regions where climate change is anticipated to intensify extreme events such as droughts, the vitality of vulnerable species may be reduced. The sensitivity of key-species to the climatic conditions may illustrate their adjustability in specific areas and assist decision making towards proper mitigation and adaptation measures. Pinus nigra, commonly known as black pine, is an endemic species, forming many protected habitats in the Mediterranean. In this study, black pine tree-ring data from Greece are used to assess the response of tree growth to specific temperature-related (mean, max. and min. temperature and diurnal temperature range) and water-related (precipitation, evapotranspiration, relative humidity and vapor pressure deficit) meteorological parameters. Additionally, the effect of drought episodes is estimated using indices, including the well-established standardised precipitation index (SPI) and reconnaissance drought index (RDI), as well as two recently proposed modifications, namely, the agricultural SPI (aSPI) and the effective RDI (eRDI). The outcomes reveal several seasonal patterns, emphasising the sensitivity of black pine principally to water-related meteorological parameters, with winter and early spring conditions having a primary role on annual tree growth. Black pine seems to be tolerant to drought in the study region, in terms of its resilience; however, there are indications that multiyear droughts may have prolonged effects on tree growth, which may last approximately three years after drought ends. Additionally, it is derived that both aSPI and eRDI illustrate more efficiently tree growth response to drought, indicating that these modifications provide increased accuracy regarding drought characterisation in the forest environment

Drought Severity and Trends in a Mediterranean Oak Forest

Drought is a significant natural hazard with widespread socioeconomic and environmental impacts. This study investigated the long-term drought characteristics in a Mediterranean oak forest ecosystem using the Standardized Precipitation Evapotranspiration Index (SPEI) at various time scales and seasons. The analysis was based on a long-term time series dataset obtained from a meteorological station located at the University Forest of Taxiarchis in Greece. The dataset encompassed a substantial time span of 47 years of continuous monitoring, from 1974 to 2020. To accomplish the goals of the current research, the SPEI was calculated for 3, 6, 12, and 24-month periods, and drought events were identified. The Mann-Kendall (M-K) test was used to analyze the trends in drought severity and evaluate the trends significance. The results showed that shorter time scales (SPEI3 and SPEI6) were more efficient for identifying short-term droughts, while longer time scales (SPEI12 and SPEI24) were better for identifying less frequent but longer-lasting drought episodes. The analysis consistently revealed positive trends across all seasons and time scales, indicating an overall transition towards wetter conditions. Nearly all the data series for SPEI12 and SPEI24 exhibited statistically significant upward trends (wetter conditions) at a 95% confidence level. However, more intense events were detected during the recent decade using the seasonal analysis. Additionally, as the time scale expanded, the magnitude of these trends increased. The findings contributed to a better understanding of drought dynamics in Mediterranean oak forests and provided valuable information for forest management and climate change adaptation planning

Encounters between forest hydrology, meteorology and philosophy of environmental education in the era of the Anthropocene

The paper investigates water in the forest ecosystem through an interdisciplinary prism combining hydrology with meteorology, environmental education and environmental ethics. The research aimed at producing a pedagogical methodology of familiarising with the hydrological cycle in the forest, not with its stereotypical and knowledge-centred approach, but with a framework that would support an experiential, ecocentric and holistic way of environmental learning in the Anthropocene. The research process was implemented through a hybrid approach of action research and took place through research teams’ encounters with water in the forest ecosystem of Dirfys, Evia. Our hydro-pedagogies in the forest manifest through a spiral pedagogical process of experiencing, feeling and thinking with water, which flows in four cycles: a) exploring with water, b) empathising with water, c) interconnecting with water, and d) reflecting with water. Our proposed hydro-pedagogies flow in the Hydranthropocene as an alternative view to pedagogical research and praxis with water visualising an ecocentric, watery common future

Incorporating aSPI and eRDI in Drought Indices Calculator (DrinC) Software for Agricultural Drought Characterisation and Monitoring

The agricultural sector is vulnerable to extreme phenomena such as droughts, particularly in arid and semi-arid environments and in regions where water infrastructure is limited. Devising preparedness plans, including means for efficient monitoring and timely identification of drought events, is essential for informed decision making on drought mitigation and water management, especially for the water-dependant agricultural sector. This paper presents the incorporation of two new drought indices, designed for agricultural drought identification, in Drought Indices Calculator (DrinC) software. These indices, namely the Agricultural Standardized Precipitation Index (aSPI) and the Effective Reconnaissance Drought Index (eRDI), require commonly available meteorological data, while they employ the concept of effective precipitation, taking into account the amount of water that contributes productively to plant development. The design principles of DrinC software leading to the proper use of the indices for agricultural drought assessment, including the selection of appropriate reference periods, calculation time steps and other related issues, are presented and discussed. The incorporation of aSPI and eRDI in DrinC enhances the applicability of the software towards timely agricultural drought characterisation and analysis, through a straightforward and comprehensible approach, particularly useful for operational purposes

Micrometeorological and Hydraulic Properties of an Urban Green Space on a Warm Summer Day in a Mediterranean City (Attica–Greece)

Urban Green Spaces (UGSs) are considered the most effective tool to mitigate Urban Heat Islands (UHIs). The optical properties of the materials and the vegetation types of the UGSs affect their surface temperatures, directly influencing their cooling ability. The hydraulic properties of urban soils are also affected by the vegetation coverage. The aim of this study is to investigate the temperature and reflected radiation (albedo) differences between UGS’s elements, around noon on a warm summer day, in Greece. The results indicate that green elements have smaller surface temperatures and higher reflectance compared to the artificial or the dry bare soil, presenting differences with the direct air temperature (measured above the surfaces with unshielded thermometers) −5.5 °C (shrubs), −3.8 °C (grass), +7.8 °C or +8.7 °C (paved surfaces inside or outside the UGS), +10.8 °C (dry bare soil), +12.2 °C (concrete) and +12.5 °C (asphalt), and albedo values 0.14 (grass and shrubs), 0.15 (dry bare soil), 0.27 (concrete), 0.21 (asphalt) and 0.20 (paved surfaces). The tree shades also produce great surface differences. The unsaturated hydraulic conductivity of the urban soil is greater than the surfaces covered with grass compared to the shrub-covered or bare soil, presenting values of 27.6, 10.8 and 11.4 mm h−1, respectively

Temporal Variations in Temperature and Moisture Soil Profiles in a Mediterranean Maquis Forest in Greece

Soil moisture (SM) and temperature (ST) are critical factors in forest eco-hydrological research. In this study, we investigated the inter- and intra-annual changes in SM and ST profiles in a mixed Mediterranean maquis forest stand together with soil and meteorological parameters. Hourly data from three field measurements points at four depths (−5, −20, −40 and −70 cm) for 6 years were interpolated using the kriging method to produce annual SM and ST profiles. The results indicate that air temperature highly affects the upper 5 cm of the mineral soil. In general, it increases with depth in winter at an average rate of 0.036 °C/cm and decreases in summer (0.035 °C/cm), presenting higher values compared to air temperature from April to August and lower ones during the rest of the period. Precipitation is the main factor driving SM variations up to a superficial soil depth of 40 cm. The upper soil layer (0–40 cm) infiltrates water faster and presents high SM variability, especially in monthly and seasonal (year to year) time steps. The maquis forest stands are likely to be strongly affected by climate change, therefore the results of this study could be useful in hydrological and climate change studies focused on maquis vegetation water management

Generation Z Worries, Suffers and Acts against Climate Crisis—The Potential of Sensing Children’s and Young People’s Eco-Anxiety: A Critical Analysis Based on an Integrative Review

The adverse and severe impacts of climate-induced natural hazards, which are expected to be aggravated by climate change, are forming a wider outline of the environmental crisis, being a source of negative emotions for human societies. Children and young people, in particular, are one of the most vulnerable social groups to this distress. In this research, we intend to analyze the eco-anxiety and climate anxiety aspects of Generation Z, based on a critical review of studies on children’s and young people’s ecological feelings worldwide, alongside a study of actual data on natural disasters per country since the year 2000. The results of the research revealed that (a) Generation Z worries in the Global North and suffers in the Global South, (b) Generation Z acts against climate change, and (c) there is an existential dimension of children’s and young people’s eco-anxiety. The study also highlights dimensions of eco-anxiety that are under-researched and are important to explore in the future. Empathizing with Generation Z’s emotional state in relation to ecological crisis and climate change may affect and highlight new directions in environmental thought and awareness

A note on some uncertainties associated with Thornthwaite's aridity index introduced by using different potential evapotranspiration methods

Potential evapotranspiration (PET) is a key parameter for climate classification and aridity assessment. The widely used UNEP (1992) classification system is based on the estimation of the aridity index AI, which requires annual average values of precipitation P and PET. For the calculation of PET the Thornthwaite's (1948) formula is, in principle, suggested. Recent studies use more advanced and accurate methods for PET estimation but apply to AI the same thresholds proposed by UNEP for aridity classification. This work deals with the uncertainties introduced by the use of different PET methods in the estimation of the aridity index AI. Specifically, the Hargreaves-Samani (HS) method and four of its modifications, three modifications of Thornthwaite's formula and the equation of Hamon, are evaluated against the widely used Thornthwaite's original method, by assessing their impact on the AI. Climatic data as monthly average values of at least 30 years of measurements from 122 stations in the Greek peninsula are used. Results show that AI is highly affected by the PET method adopted, resulting thus to changes in climatic classification of a region. Further, results imply the need for an adjustment of the threshold values that determine aridity classes according to the method each time adopted. Therefore, new threshold values for the aridity classes are developed and presented in this work. The proposed threshold values cover a range of sites that belong to semi-arid SA, sub-humid SH and humid H aridity classes of the Greek peninsula