Mediterranean Environment Research Articles

Precipitation timing and soil substrate drive phenology and fitness of Arabidopsis thaliana in a Mediterranean environment

Abstract In Mediterranean climates, the timing of seasonal rains determines germination, flowering phenology and fitness. As climate change alters seasonal precipitation patterns, it is important to ask how these changes will affect the phenology and fitness of plant populations. We addressed this question experimentally with the annual plant species Arabidopsis thaliana. In a first experiment, we manipulated the date of rainfall onset and recorded germination phenology on sand and soil substrates. In a second experiment, we manipulated germination date, growing season length and mid‐season drought to measure their effects on flowering time and fitness. Within each experiment, we manipulated seed dormancy and flowering time using multilocus near‐isogenic lines segregating strong and weak alleles of the seed dormancy gene DOG1 and the flowering time gene FRI. We synthesized germination phenology data from the first experiment with fitness functions from the second experiment to project population fitness under different seasonal rainfall scenarios. Germination phenology tracked rainfall onset but was slower and more variable on sand than on soil. Many seeds dispersed on sand in spring and summer delayed germination until the cooler temperatures of autumn. The high‐dormancy DOG1 allele also prevented immediate germination in spring and summer. Germination timing strongly affected plant fitness. Fecundity was highest in the October germination cohort and declined in spring germinants. The late flowering FRI allele had lower fecundity, especially in early fall and spring cohorts. Projections of population fitness revealed that: (1) Later onset of autumn rains will negatively affect population fitness. (2) Slow, variable germination on sand buffers populations against fitness impacts of variable spring and summer rainfall. (3) Seasonal selection favours high dormancy and early flowering genotypes in a Mediterranean climate with hot dry summers. The high‐dormancy DOG1 allele delayed germination of spring‐dispersed fresh seeds until more favourable early fall conditions, resulting in higher projected population fitness. These findings suggest that Mediterranean annual plant populations are vulnerable to changes in seasonal precipitation, especially in California where rainfall onset is already occurring later. The fitness advantage of highly dormant, early flowering genotypes helps explain the prevalence of this strategy in Mediterranean populations. Read the free Plain Language Summary for this article on the Journal blog.

Clipping Effect on the Grain Nitrogen and Protein Fractions of Ancient and Old Wheats Grown in a Mediterranean Environment

This study is the first to assess the effects of clipping, cultivar, season, and their interactions on the protein composition of six old and ancient wheat cultivars (n = 6). For this, nitrogen content, the proportion of wheat protein fractions, and the molecular weight distribution of the extractable and unextractable glutenin polymers were investigated as a function of cultivar and clipping in two consecutive seasons. The relationships between genotypic variation in grain nitrogen and protein fraction content under clipping and non-clipping conditions were also assessed. Clipping delayed and shortened the grain filling period of all of the cultivars. The protein composition of some cultivars behaved differently to clipping due to differences in the environmental conditions of S1 (exceptional dry season) and S2 (rainy season). In S1, clipping decreased the ratio of gliadins over glutenins (GLI/GLU) (<1) of Cappelli and Giovanni Paolo, while in S2, clipping improved the GLI/GLU of Giovanni Paolo, Monlis, and Norberto. The unextractable polymeric proteins were not affected by clipping. Khorasan was shown to be indifferent to clipping in S1 and S2. These results suggest that it is possible to have ancient/old wheats suitable for a dual-purpose system, in different climatic conditions, while maintaining good grain quality traits. The increased market demand for ancient and old wheats presents an economic opportunity for farmers who adopt the dual-purpose technique to cultivate these resilient crops again and increase their profit margins and revenues.

Protection net and the canopy layer decouple gas exchanges, affecting carbon and water fluxes: the case of a kiwifruit orchard in a Mediterranean environment

Protection net and the canopy layer decouple gas exchanges, affecting carbon and water fluxes: the case of a kiwifruit orchard in a Mediterranean environment

Does Caulerpa prolifera with Its Bacterial Coating Represent a Promising Association for Seawater Phytoremediation of Diesel Hydrocarbons?

Anthropic diesel-derived contamination of Mediterranean coastal waters is of great concern. Nature-based solutions such as phytoremediation are considered promising technologies to remove contaminants from marine environments. The aim of this work was to investigate the tolerance of the Mediterranean autochthonous seaweed Caulerpa prolifera (Forsskal) Lamouroux to diesel fuel and its hydrocarbon degradation potential. Changes in C. prolifera traits, including its associated bacterial community abundance and structure, were determined by fluorescence microscopy and next-generation sequencing techniques. Thalli of C. prolifera artificially exposed to increasing concentration of diesel fuel for 30 days and thalli collected from three natural sites with different levels of seawater diesel-derived hydrocarbons were analysed. Gas chromatography was applied to determine the seaweed hydrocarbon degradation potential. Overall, in controlled conditions the lower concentration of diesel (0.01%) did not affect C. prolifera survival and growth, whereas the higher concentration (1%) resulted in high mortality and blade damages. Similarly, only natural thalli, collected at the most polluted marine site (750 mg L-1), were damaged. A higher abundance of epiphytic bacteria, with a higher relative abundance of Vibrio bacteria, was positively correlated to the health status of the seaweed as well as to its diesel-degradation ability. In conclusion, C. prolifera tolerated and degraded moderate concentrations of seawater diesel-derived compounds, especially changing the abundance and community structure of its bacterial coating. The protection and exploitation of this autochthonous natural seaweed-bacteria symbiosis represents a useful strategy to mitigate the hydrocarbon contamination in moderate polluted Mediterranean costal environments.

Effect of Solid Digestate Amendment on The Dynamics of N Soluble Forms in Two Contrasting Soil Profiles under Mediterranean Environment

Use of solid agricultural digestate as a substitute for chemical fertilizers in Mediterranean cropping systems can be a valuable approach to improving soil fertility. However, it is important to accurately assess its mineralisation dynamics in order to avoid uncontrolled nutrient releases in agroecosystems. With this aim, a field experiment was conducted to evaluate the effects of solid digestate application on total soil nitrogen (TSN), extractable organic N (EON) and mineral N forms (NH4+-N and NO3−-N) in two Mediterranean soil profiles (clay and sandy-loam) over one year. The solid digestate increased TSN and EON concentrations in the upper soil layer (0–20 cm) of both soils, more in the clay soil, with a decreasing effect in the lower soil layers (20–40 and 40–60 cm). The amendment increased NH4+-N concentrations, with a greater and longer-lasting effect in the clay soil, especially in the first two soil layers (0–20 and 20–40 cm), while in the lowest, it was limited at the first sampling epoch. The NO3−-N copied the NH4+-N trends in both soils, with a greater effect on the 0–20 cm soil layer at all sampling epochs. The present study suggests that solid digestate, applied at a dose of 30 Mg ha−1, can be a useful alternative to mineral N fertilisers for clay and sandy-loam soils in Mediterranean orchards.

Use of Logs Downed by Wildfires as Erosion Barriers to Encourage Forest Auto-Regeneration: A Case Study in Calabria, Italy

The easy implementation of ecologically-sound remediation measures for the prompt stabilisation of burned areas may be crucial in Mediterranean forest environments. Manual in situ contour redirection of burned felled logs could aid in soil erosion control and facilitate forest self-regeneration. In this study, a plot-scale runoff/sediment yield survey was conducted in Calabria, Italy, within a Mediterranean pine forest that was affected by an extreme wildfire spanning over 15,000 hectares in the summer of 2021. The hydrological response to 24 rainfall events was analysed after one year of monitoring using nine Wischmeier and Smith 20% sloping plots, which were distributed into three plot-blocks representing different conditions (forested, burned with randomly directed fallen logs, and burned with fallen logs manually redirected along contour lines). The post-fire condition (with felled logs in random positions) exhibited a consistent overall increase (approximately four times) in runoff and sediment yield compared to the pre-fire situation. This degradation effect was mitigated by approximately 30% through the manual redirection of burned logs, which promoted early (three to five weeks) vegetation regeneration (including tree emergence) and enhanced coverage as vegetation spread from the log positions. The results obtained so far provide encouraging insights and warrant further research on steeper slopes and complementary aspects (regulatory, biological, mechanical, economic, etc.).

Late Holocene filling of the Canale di Imbocco (Portus, central Italy): a multidisciplinary palaeoenvironmental perspective

Portus was the main port of imperial Rome from the 2nd century AD to the 5th century AD, with an inner, hexagonal port (Trajan basin) and an outer port (Claudius basin) linked by a channel bounded by quays. Six sedimentary facies have been differentiated in the geological analysis of a core extracted in this channel, basically composed of poorly classified bioclastic muds typical of restricted environments, accumulations of Posidonia oceanica (Linnaeus) Delile, 1813 and a final anthropic fill. The subfossil record of bivalves, foraminifera and ostracods is characteristic of Mediterranean brackish environments (lagoons, estuaries, deltas) with significant environmental stress, due to changes in the physical-chemical parameters and probably the periodic dredging of this seaway during a period of about 300 years. The presence of “Neptune balls” points to the development of probable stormy periods that deposit these unique structures in the internal areas of this historic port.

Oribatid mites in different Mediterranean crop rotations fertilized with animal droppings.

Unsustainable soil management is one of the drivers of soil degradation, but impact assessment requires the development of indicators. Oribatids might be considered as early indicators of disturbances due to the stability of their community. The aim of this study was to investigate the feasibility of oribatids as bioindicators of sustainable agricultural practices. Under a dry Mediterranean climate, three fertilization experiments - two under a two-crop rotation system and one under maize monoculture and established 12 years earlier - were sampled 3× for oribatid identification during the last annual cropping cycle. The hypothesis was that different nutrient and crop managements affect the number of oribatid species and individuals present, and these parameters could be used as indicators of soil degradation. In total, 18 oribatid species were identified, and 1974 adult individuals were recovered. Maximum abundance was found prior to sowing. Pig slurry (PS) vs. control, and dairy cattle manure (CM) vs. mineral fertilization increased oribatid abundance. This increase was evident when the average applied rates with PS were ca. 2 Mg of organic matter (OM) ha- 1 yr- 1, or higher than ca. 4 Mg OM ha- 1 yr- 1 for CM. When the preceding crop was wheat and PS or CM were used, Oribatula (Zygoribatula) excavata (which reproduces sexually) predominated. In maize monoculture fertilized with CM, Tectocepheus sarekensis and Acrotritia ardua americana (which can reproduce through parthenogenesis) prevailed vs. Oribatula, which indicated a heavily disturbed soil. Under this specific Mediterranean environment, the predominance of certain parthenogenic oribatid species and the number of individuals provide advanced warning on soil degradation.

Landscape heterogeneity increases the stability of wild ungulate populations facing climatic variability in Mediterranean ecosystems

Mediterranean environments are characterized by strong intra- and inter-annual fluctuations in plant primary production, which are likely to regulate the carrying capacity and density-dependent responses of ungulate populations. These effects may, however, vary across spatial and temporal scales. Habitat heterogeneity, particularly when associated to differentiated phenological responses, may allow wild ungulates to mitigate temporal fluctuations in plant production by using different resources along the year. In this work, we use a 15-years dataset (including remote-sensing data on vegetation distribution, phenology and production, as well as ungulate population counts) to assess how temporal variability in plant primary production and livestock abundance influence the population dynamics of two wild ungulates: native red deer, Cervus elaphus, and introduced fallow deer, Dama dama. Results show that temporal alternation in the phenological cycles of the four different vegetation types increased plant production, thus food availability for ungulates, within each year. Furthermore, complementarity in the responses of different vegetation types to variations in the amount and timing of rainfall increased the predictability of food availability across different years. This complementarity effect was further increased by the contrasting responses of ungulate populations to variation in the production of different vegetation types. Furthermore, domestic ungulates had positive effects on wild ungulate density at low to intermediate abundances, but high livestock densities decreased ungulate density and constrained the stability of the plant-ungulate system in response to the impact of climatic variation, particularly under climate change. Our findings deepen the knowledge on vegetation-ungulate interactions in Mediterranean areas, potentially contributing to develop better management strategies of ungulate populations and adapt them to ongoing climate change.

Phenotypic variation in leaf photosynthetic traits, leaf area index, and carbon discrimination of field-grown wheat genotypes and their relationship with yield performance in Mediterranean environments.

Leaf water potential, gas exchange, and chlorophyll fluorescence exhibited significant differences among genotypes, high environmental effects, but low heritability. The highest-yielding and drought-tolerant genotypes presented superior harvest index and grain weight, compared to drought-susceptible ones. Physiological phenotyping can help identify useful traits related to crop performance under water-limited conditions. A set of fourteen bread wheat genotypes with contrasting grain yield (GY) was studied in eight Mediterranean environments in Chile, resulting from the combination of two sites (Cauquenes and Santa Rosa), two water conditions (rainfed-WL and irrigated-WW), and four growing seasons (2015-2018). The objectives were to (i) evaluate the phenotypic variation of leaf photosynthetic traits after heading (anthesis and grain filling) in different environments; (ii) analyze the relationship between GY and leaf photosynthetic traits and carbon isotope discrimination (Δ13C); and (iii) identify those traits that could have a greater impact in the determination of tolerant genotypes under field conditions. Agronomic traits exhibited significant genotypic differences and genotype × environment (GxE) interaction. The average GY under the WW condition at Santa Rosa was 9.2Mgha-1 (range 8.2-9.9Mgha-1) and under the WL condition at Cauquenes was 6.2Mgha-1 (range 3.7-8.3Mgha-1). The GY was closely related to the harvest index (HI) in 14 out of 16 environments, a trait exhibiting a relatively high heritability. In general terms, the leaf photosynthetic traits presented low GxE interaction, but high environmental effects and low heritability, except for the chlorophyll content. The relationships between GY and leaf photosynthetic traits were weaker when performed across genotypes in each environment, indicating low genotypic effects, and stronger when performed across environments for each genotype. The leaf area index and Δ13C also presented high environmental effects and low heritability, and their correlations with GY were influenced by environmental effects. The highest-yielding and drought-tolerant genotypes presented superior HI and grain weight, but no clear differences in leaf photosynthetic traits or Δ13C, compared to drought-susceptible ones. It seems that the phenotypic plasticity of agronomic and leaf photosynthetic traits is very important for crop adaptation to Mediterranean environments.

Combining multiple geostatistical analyses to assess the past, present, and future of fragile Mediterranean deltaic environments

Littoral plains in general and those of the Mediterranean rivers and ramblas, are highly vulnerable territories. Understanding the past and present conditions of these areas is the best strategy to design efficient land management plans to prevent degradation such as pollutants, soil sealing, erosion, etc. in the near and medium future. In this research, different mapping techniques (land-use changes in twelve different years using manually digitalisation and field observations, from 1956 to 2019, and pattern analysis using ecological landscape indexes), multivariate statistical analyses (Spearman rank coefficient and Principal Component Analysis), and predictive models (Markov chain) are combined to assess the past, current, and future status of the Vélez River delta (Málaga province, Southern Spain), a representative vulnerable territory situated in the popular touristic area of Costa del Sol. We also included a demographic analysis using annual population census data (current inhabitants and projections) and a climate trend analysis (Mann-Kendall test) considering temperatures, precipitations and wind data. Our results demonstrate that the drastic urbanization, including new settlements, roads, and ways, has negatively impacted the delta area, even the alluvial plain, beaches, and natural sand deposits. From 1956 to 2019, >70 ha of deltaic area have been lost. The largest category of land-use, cultivated fields, accounted for up to 72.4 % of the total delta area in 1984. However, this was reduced to 41.1 % by 2019. The alluvial plain and beaches/sand deposits started from 9.3 and 11.8 %, and decreased to 5.2 and 5.9 %, respectively. Also, climate change (especially in temperature) could affect some spatial patterns. Predictive models reveal that it is likely that abandoned spaces, sand deposits, and beaches, will be transformed into new urban areas and, to a lesser extent, into cultivated fields. We concluded that the conservation of the cultivated lands, although decreasing in the area over the studied period, obtained the highest correlation with the delta conservation. Therefore, we affirm that efficient plans, which promote specific changes in land use, would contribute to stopping the degradation of the delta such as pollution of natural areas or soil sealing. Specifically, a plan should be developed to preserve sustainable agriculture and control urban sprawl.

An innovative cooling technique for floating photovoltaic module: Adoption of partially submerged angle fins

Once the temperature of a photovoltaic panel elevates, two major impacts occur: a significant loss in output power and thermal deterioration, which severely shortens the panel's lifespan. Non-uniform distribution of working temperatures and hence heat spots promote power loss and long-term thermal deterioration. As an electronic power generator, a solar photovoltaic panel requires prompt heat removal from its surfaces to tackle such issues. This is accomplished in the current study by utilizing a novel design heat sink composed of partially submerged angle perforating fins (PSAPF) targeted at increasing heat dissipation from a floating photovoltaic system (FPV). The proposed PSAPF was experimentally investigated for excess heat removal from FPV via both air and water mediums under Mediterranean outdoor environments at Port Said, Egypt. It was demonstrated that in the presence of a surface water current of 0.3 m/s, wind of 5 m/s with direction of 60°, employing PSAPF was considerably more efficient, with 22.77% more productivity and a 33.31% operating temperature reduction when compared to a conventional FPV system. A regression equation has been formed to predict the performance of the designed system through several factors affecting its performance over a wide range of variances.

Drought Impact on the Morpho-Physiological Parameters of Perennial Rhizomatous Grasses in the Mediterranean Environment

The selection of non-food crops for bioenergy production in limiting environments is a priority for energy security and climate change mitigation. Therefore, more studies are needed on the interactions between species and environmental factors in specific sites which allows their selection for biomass production. The objective of this work is to study the impact of drought on the morpho-physiological parameters of perennial rhizomatous grasses Panicum virgatum L., Miscanthus × giganteus, and Arundo donax L. in the Mediterranean environment. Plants were grown on field and trials were carried out under support-irrigation and rainfed conditions during two consecutive years. Morpho-physiological parameters were measured in May, June and August, and dry biomass at the end of the experiment. Under rainfed conditions, A. donax presented the highest photosynthesis rate (25, 15 and 10 CO2 m−2 s−1), relative water content (85–90%), and dry biomass (~4500 g plant−1) compared with P. virgatum (20, 5 and 5 CO2 m−2 s−1, 65–85% RWC and ~1400 g plant−1) and Miscanthus (18, 4 and 0 CO2 m−2 s−1, 80–10% RWC and ~260 g plant−1). It is concluded that A. donax would be the best perennial rhizomatous grass to be used as bioenergy crop under Mediterranean conditions.

Agronomic Response to Irrigation and Biofertilizer of Peanut (Arachis hypogea L.) Grown under Mediterranean Environment

Peanut is a staple crop suitable for mechanized harvest and a source of plant proteins and fatty acids. It is widespread in Asia and North America, while there is limited cultivation in Europe despite potentially favorable climatic conditions. To test the adaptability of peanut in the Mediterranean area, a two-year field trial was carried out with one Spanish-type and one Virginia-type genotype cultivated under two water regimes (full irrigation and half irrigation supply). In order to test the response to fertilization management, three treatments were carried out, including an unfertilized control, a N-fertilized treatment, and a N-fertilized treatment inoculated with a commercial mixture of plant-growth promoting microorganisms, including two Bacillus species, Trichoderma and arbuscular mycorrhizal fungi (AMF). Microbiological soil analysis assessed the robustness of bacilli and their viability in soil. The Virginia-type genotype showed a better adaptability, with a positive response to irrigation and biofertilization. In particular, the inoculated treatment led to the highest agricultural crop water productivity, with important implications for sustainability. The impact of agronomic strategies was evaluated also in relation to storage proteins. The expression of 7s vicilin fraction showed a variability associated with water supply.

Evaluation of the yield of strawberry genotypes by morpho-physiological parameters under deficit irrigation in the Mediterranean environment

The most pressing concern of the century is food security, mostly supported by irrigated agriculture. In this respect, studies on water stress have drawn increased attention with a highlighting expectation foreseen via our breeding efforts documented in this study concerning the significant commercial strawberry cultivars ‘Rubygem’, ‘Sabrina’ and ‘Festival’ along with some selected superior bred lines (‘33’, ‘36’, ‘59’, ‘61’ and ‘112’). Plants cultivated in the Spanish-type high tunnel were exposed to both full (IR100) and deficit irrigation (IR50) in the Mediterranean part of Türkiye. Fruit yield as well as certain critical morphological and physiological parameters were examined throughout the active harvest period. This study found that the parameters relating to the vegetative components, as well as the fruit weight and yield, drastically dropped when plants were subjected to deficit irrigation. Therefore, depending on the limited irrigation, as a result of the closure of stomata, it was concluded that the amount of water and stomatal conductance of the plant is associated with a decrease. IR50 was found to have less impact on low-yield genotypes than on high-yield genotypes. Photosynthetic activity and stomatal conductivity were high in the ‘33’ bred line with a high yield. On the other hand, photosynthesis activity and leaf water potential (LWP) values were relatively low in the ‘36’ bred line with low yield. The study proved that variables like photosynthetic activity, stomatal conductance, and LWP could be used as markers for high yield genotype selection.

Combined use of biochar and sprinkler irrigation may enhance rice productivity in water-stressed regions

A 2-year field experiment was conducted to analyse the effects of fresh and aged biochar on soil properties, as well as herbicide effectiveness and rice-yield components in a Mediterranean environment. Six managements were used: no-tillage and sprinkler irrigation either without (NoT) or with first-year biochar application (NoTB), conventional tillage and sprinkler irrigation either without (ConvT) or with first-year biochar application (ConvTB), conventional tillage and flooding irrigation either without (ConvTF) or with first-year biochar application (ConvTFB). The measurements done in the first (2018) and second (2019) years after biochar addition were taken to determine its fresh and aged effects, respectively. The application of biochar led to an improvement of the soil properties such as increase in the soil's organic carbon content, pH, and dehydrogenase activity. It also reduced weed pressure, regardless of the management used, and sprinkler systems were found to have the greatest herbicide effectiveness, especially in ConvT and ConvTB. In terms of production, there were significant increases in yield with the application of fresh biochar, in the amended managements under tillage compared with their unamended counterparts. The greatest yields were found under ConvT and ConvTB, with mean values for both treatments of 10,770 and 11,299 kg ha−1 in the fresh and aged years, respectively. Furthermore, water productivity reached its greatest values when sprinkler was used, especially with tillage for which the application of fresh biochar increased water productivity by a factor of 1.09 relative to ConvT. Therefore, sprinkler irrigation in combination with tillage and biochar applications can be regarded as an efficient alternative to flooding irrigation in order to ensure productive viability of rice in water-stressed regions.

Human-Impact Gradients through Anthropogenic Pollen Indicators in a Mediterranean Mosaic Landscape (Balearic Islands)

This paper proposes new anthropogenic pollen indicators for the Balearic Islands and attempts to assess gradients of human impact on vegetation in Mediterranean islands. A combination of modern pollen analogue studies, complemented by phytosociological descriptions and ordination techniques using quantitative and presence/absence data was used. Redundancy analysis allowed us to evaluate the relationships between pollen types and significant environmental variables and propose regional (e.g., Centaurea, Rubus, Plantago lanceolata-t) and local/microregional anthropogenic pollen indicators (e.g., Cerealia, Poygonum aviculare, Matricaria-t). Additionally, an anthropogenic index score (AIS) for each sampled location was calculated to correlate each pollen type to a specific degree of human impact: (a) low (e.g., Cerastium-t, Erica arborea-t, Cistus albidus), (b) moderate (e.g, Sinapis-t, Sanguisorba minor-t, Plantago bellardii-t), (c) high (e.g., Papaveraceae undiff., Dipsacaceae, Secale-t). This paper contributes to a further understanding of land-use dynamics and to defining the degree of impact, which is especially necessary to assess colonization and anthropization rhythms in Mediterranean island environments.

Generation of climate change scenarios for rainfall and temperature using SDSM in a Mediterranean environment: a case study of Boufakrane river watershed, Morocco

Climate change is the global phenomenon of climate transformation characterized by changes in the planet’s habitual climate. The main objective of this work is to assess and predict climate change for the 2015–2100 period, in the Boufakrane river watershed, Morocco. In this study, the Statistical DownScaling Model (SDSM) method has been used to generate the climate scenarios for rainfall and temperature related to Representative Concentration Pathway (RCP) scenarios such as RCP 2.6, RCP 4.5, and RCP 8.5. For this purpose, the region’s annual, monthly, and daily rainfall records were analyzed. A rainfall index was calculated to differentiate and distinguish between dry and humid years of the climate series, and a non-parametric Pettitt’s test has been applied to determine the trend of precipitation series for the projection period. The application of Pettitt’s test with a confidence interval of 99% and a significance level of 0.05 shows a break in the 1979/80 rainfall series, with an average of 675.78 mm and 511.94 mm respectively before and after the break. The combined application of the two approaches of SDSM, and the non-parametric Pettitt test for the period 2015–2100, showed a downward trend of annual rainfall with 17.29% for RCP 2.6. While no trend was recorded for the two scenarios RCP 4.5, and RCP 8.5. Therefore, this study highlighted the importance and urgent need for developing strategies and decision-making plans for climate change adaptation for sustainable water resources management.Graphical

UAV-derived photogrammetric point clouds and multispectral indices for fuel estimation in Mediterranean forests

Sensors attached to unmanned aerial vehicles (UAVs) allow estimating a large number of forest attributes related to forest fuels. This study assesses photogrammetric point clouds and multispectral indices obtained from a fixed-wing UAV for the classification of Prometheus fuel types in 82 forest plots in Aragón (NE Spain). Images captured by an RGB camera and a multispectral sensor allowed generating high density photogrammetric point clouds (RGB: 3000 points/m2; multispectral: 85 points/m2), which were normalized using alternatively a Digital Elevation Model (DEM) of 0.5, 1, and 2 m resolution. A set of structural and textural variables were derived from the normalized point cloud heights, and for the latter, the gray-level co-occurrence matrix (GLCM) approach was used. Multispectral images were also used to create seven spectral vegetation indices. The most relevant structural, textural, and spectral variables to introduce into the fuel types classification models were selected using Dunn's test, which included: the vegetation height at the 50th percentile, the coefficient of variation of the heights, the percentage of returns above 4 m, the mean textural dissimilarity, and the mean of the Green Chlorophyll Index. Three different data samples were introduced in the models: i) the relevant structural and textural variables from the RGB camera (RGB data sample); ii) the relevant structural, textural, and spectral variables from the multispectral sensor (MS data sample); and iii) the relevant structural and textural variables from the RGB camera plus the relevant spectral variable from the multispectral sensor (integrated data sample). After comparing three machine learning classification techniques (Random Forest, and Linear and Radial Support Vector Machine), the best results were obtained with Random Forest with k-fold cross-validation (k-10) and the integrated data sample with normalized point clouds at 0.5 m DEM resolution (overall accuracy = 71%). The variables successfully identified the Prometheus main fire carriers (i.e., shrubs or trees) and confusions were mainly located within the fuel types of the same dominant stratum, especially in fuel types 3 and 6. These results demonstrate the ability of UAV imagery to classify forest fuels in Mediterranean environments when RGB and multispectral data are combined.

Individuation of the best agronomic practices for organic durum wheat cultivation in the Mediterranean environment: a multivariate approach

BackgroundThe main challenge of organic cereal systems is ensuring high yields and grain quality while maintaining pedo-environmental sustainability. Despite the potential benefits of organic farming systems, a debated limitation is their actual contribution to food security. Durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.], one of the most important staple food crops, is mainly grown in the Mediterranean environments, where farmers have to face profound inter-annual fluctuations in productions, expecially under organic system, due to prolonged drought and heat spells. With the overarching objective of deriving practical indications to support organic wheat production in the Mediterranean region, we tested the effect of nitrogen and sulphur-based organic foliar fertilizers on two ancient and two modern durum wheat varieties grown in two seasons (2018–2019) characterized by different weather conditions. Moreover, we evaluated the effect of a foliar application of Selenium at booting on grain yield and quality.ResultsResults from the Principal Component analysis revealed that seasonal weather and the varietal choice determined most of the variability of yield and quality traits, while Selenium application markedly affected the performance of organic durum wheat, especially in the milder season. The Cluster Analysis computed on the Principal Components revealed three groups, representative of (i) the modern variety, Marco Aurelio, grown in the dryest season (average yield, low protein content), (ii) all varieties grown in 2018, with the addition of sodium selenate (high yield, high protein content), and (iii) the ancient variety, Cappelli, grown in both seasons (low yield, average protein content).ConclusionsThis study evidenced that tailored agronomic practices are needed to sustain the organic durum wheat systems in the Mediterranean area. The promising beneficial effect of Selenium would deserve a dedicated research program, where additional experiments should further investigate its impact on organic durum wheat yield and quality. The multivariate approach permitted us to identify the most effective agronomic practices in relation to different environmental conditions; the outputs from this study are ready to be transferred to organic farmers aiming at improving the performance of durum wheat systems and at providing an effective contribution to food security.