Mediterranean Plant Species Research Articles

Effect of stand-replacing fires on Mediterranean plant species in their marginal alpine range

In the southern side of the Alps, many relic species with Mediterranean and sub-Mediterranean distribution were described in mild-winter, fire-prone areas. Very few studies have modeled the importance of environmental factors on their distribution. In this paper, we assessed the effect of fire on the occurrence of euri- and steno-Mediterranean (ESM) species in Pinus sylvestris forests of Aosta Valley (Italy), by analyzing vegetation in a chronosequence of six stand-replacing fires (1962–2006). We analyzed species richness along the chronosequence, and modeled it as a function of time since fire, environment, and stand structure. We observed a strong positive association between ESM and total species richness. Temporal vegetation dynamics did not follow the direct succession pattern that is commonly observed in Mediterranean ecosystems. Two distinct maxima of ESM species richness were observed: (1) short lived, ruderal species (32 % of all ESM species) in the early post-fire stages, and (2) dry grassland species (54 %) in intermediate stages. The first were facilitated by the consumption of canopy and litter during fire, while the second by delayed tree canopy closure. In multivariate models of ESM species richness, light and elevation were the only significant predictors. Contrary to expectations, time since fire was not significant. Our study suggests that stand-replacing fires play an important role in preserving Mediterranean species in the study area by maintaining an open canopy, and promote local species diversity.

Evaluation of Atriplex Halimus, Medicago Lupulina and Portulaca Oleracea For Phytoremediation of Ni, Pb, and Zn

Suitable plant species are able to accumulate heavy metals and to produce biomass useful for non-food purposes. In this study, three endemic Mediterranean plant species, Atriplex halimus, Portulaca oleracea and Medicago lupulina were grown hydroponically to assess their potential use in phytoremediation and biomass production. The experiment was carried out in a growth chamber using half strength Hoagland's solutions separately spiked with 5 concentrations of Pb and Zn (5, 10, 25, 50, and 100 mg L−1), and 3 concentrations of Ni (1, 2 and 5 mg L−1). Shoot and root biomass were determined and analyzed for their metals contents. A. halimus and M. lupulina gave high shoot biomass with relatively low metal translocation to the above ground parts. Metals uptake was a function of both metals and plant species. It is worth noting that M. lupulina was the only tested plant able to grow in treatment Pb50 and to accumulate significant amount of metal in roots. Plant metal uptake efficiency ranked as follows: A. halimus > M. lupulina > P. oleracea . Due to its high biomass production and the relatively high roots metal contents, A. halimus and M. lupulina could be successfully used in phytoremediation, and in phytostabilization, in particular.

Fire variability, as well as frequency, can explain coexistence between seeder and resprouter life histories

Summary Studies in fire‐prone Mediterranean ecosystems have repeatedly shown that the mean values of fire regimes (particularly frequency, but also size and intensity) are important for managing sensitive species and maintaining diversity. However, recent studies suggest that invariant fire regimes – that is, those with no variation about the mean value – may not be sufficient to maintain the coexistence mechanisms which could help explain the high levels of species diversity. However, there has been a little examination of the potential mechanisms by which variability in fire regimes might foster coexistence. In these species‐diverse ecosystems, fluctuations in fire regimes promote the coexistence of competitively unequal species, thus providing a potential mechanism of coexistence. We examine the role of variability in the length of the interfire interval and ask whether this variability can allow a fluctuation‐dependent mechanism, namely the storage effect, to promote the coexistence of species. We focus on dominant trade‐offs in fire regeneration strategies (i.e. obligate resprouting vs. obligate seeding) common among Mediterranean plant species and use simulations to explore the inter‐relationship between variability in the time between fires and the coexistence of species. Several empirical studies have found that variability in the length of the interfire interval improved diversity – our simulations suggested one mechanism that could explain this result. Variability can greatly increase the regions over which coexistence between two species – a fire obligate seeder and a resprouter – occurs. Synthesis and applications. Mediterranean ecosystems tend to have high plant diversity, and yet the mechanisms maintaining this diversity are often incompletely understood, and thus management actions that aim to promote coexistence may be relying on imprecise information. In general, fire events drive the evolution and maintenance of diversity and are an important management tool. It is high likely that fluctuations or variability in fire are also important, and this suggests that invariant regimes of prescribed burning or fire suppression could be detrimental to the mechanisms that play a role in the maintenance of diversity in these Mediterranean ecosystems. As a result, attention should be paid to historical fire regimes and the variation in fire return times they displayed when developing prescribed burning regimes.

Phytotoxic activity of foliar volatiles and essential oils of Calamintha nepeta (L.) Savi

Foliar volatiles and essential oils of Calamintha nepeta (L.) Savi, a Mediterranean plant species belonging to the Labiatae family, were investigated for their phytotoxic activities on seed germination and root growth of crops (Lactuca sativa L. and Raphanus sativus L.) and weed species (Lolium perenne L. and Amaranthus retroflexus L.). Foliar volatiles of C. nepeta (L.) Savi strongly inhibited both germination and root growth of lettuce, and its essential oils, especially at 125, 250 and 500 μL/L, inhibited both processes in lettuce, radish and A. retroflexus L. species, while displaying a little effect on L. perenne L. By GC–MS, 28 chemicals were identified: 17 monoterpenes, 8 sesquiterpenes, 1 diterpene and 2 miscellaneous. Pulegone was the main constituent of the C. nepeta (L.) Savi essential oils. The terpenic components of essentials oils were probably responsible for the phytotoxic activities.

Cell-based and chemical assays of the ability to modulate the production of intracellular Reactive Oxygen Species of eleven Mediterranean plant species related to ethnobotanic traditions

The aim of this study was to compare three tests for the evaluation of the antioxidant potential of eleven plant species traditionally used to cure or to enhance animal and/or human wellbeing. In addition to the ability to modulate the production of intracellular reactive oxygen species the effect of the treatment on cell viability was also considered. In the cell-based experiment DCF (2′,7′dichlorofluorescein diacetate) and in the chemical assays DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2′-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt), Pistacia lentiscus exhibited high antioxidant capacity, while Cistus creticus and Euphorbia characias were ineffective in cell-culture and displayed high activity in the chemical assays, and others (Malva sylvestris, Matricaria chamomilla, Urtica dioica) showed an opposite trend. Olea europaea (sylvestris and europaea) and Umbilicus rupestris displayed highest antioxidant efficacy in both HUVEC and HL-60 cells, and provided also appreciable activity in the chemical assays. The study gives evidence that herbal extracts may have similar antioxidant properties but different effects on cells. Therefore, it is important to combine analytical and biological testing methods in order to measure the antioxidant capacity of natural extracts. Results encourage to explore further the potential nutraceutical and functional properties of Mediterranean plant species related to ethno-botanic traditions for animal health care.

Relationships between leaf morphological traits, nutrient concentrations and isotopic signatures for Mediterranean woody plant species and communities

Soil factors are driving forces that influence spatial distribution and functional traits of plant species. We test whether two anchor morphological traits—leaf mass per area (LMA) and leaf dry matter content (LDMC)—are significantly related to a broad range of leaf nutrient concentrations in Mediterranean woody plant species. We also explore the main environmental filters (light availability, soil moisture and soil nutrients) that determine the patterns of these functional traits in a forest stand. Four morphological and 19 chemical leaf traits (macronutrients and trace elements and δ13C and δ15N signatures) were analysed in 17 woody plant species. Community-weighted leaf traits were calculated for 57 plots within the forest. Links between LMA, LDMC and other leaf traits were analysed at the species and the community level using standardised major axis (SMA) regressions LMA and LDMC were significantly related to many leaf nutrient concentrations, but only when using abundance-weighted values at community level. Among-traits links were much weaker for the cross-species analysis. Nitrogen isotopic signatures were useful to understand different resource-use strategies. Community-weighted LMA and LDMC were negatively related to light availability, contrary to what was expected. Community leaf traits have parallel shifts along the environmental factors that determine the community assembly, even though they are weakly related across individual taxa. Light availability is the main environmental factor determining this convergence of the community leaf traits.

An international workshop: mycorrhiza, a biological tool for sustainable development in Africa

Althoughmycorrhizal symbiosis are well known on European, North American, South American, Southeast Asian, and Australian plant species from natural or anthropogenic ecosystems, data from Africa are still scarce and neglected. The international workshop on “Mycorrhiza: a biological tool for sustainable development in Africa” held in Dakar, Senegal, February 21–23, 2011, was therefore particularly timely. Eighty-seven participants from 23 countries attended theworkshop, which included oral presentations, poster sessions, excursion and many free-ranging discussions. Abstracts of all the talks and posters, and details of the participants can be found on the website http://www.ird.sn/web-mycorhizes2011/. The aim of the workshop was to present state of the knowledge and perspectives in mycorrhizal research on tropical and Mediterranean plant species in Africa. The contents addressed diversity and function of mycorrhiza associated with forest and agricultural plants, in Mediterranean and tropical, wet and seasonally dry ecosystems. Impacts of mycorrhiza on plant diversity and composition, regeneration and dynamics of ecosystems, and biomass production in forestry and agriculture, were topics for oral presentations and poster sessions. The workshop was also a pretext to put in concrete form the idea of creating of a scientific network that connects researchers working with mycorrhiza in Africa. In the opening lecture, A. Fortin (Canada) introduced mycorrhiza and their role in the evolution and functioning of plants and terrestrial ecosystems. Although symbiotic systems have provided a major impetus to plant speciation and to the development of soils and therefore to terrestrial ecosystems, all concepts at the base of modern agriculture have been developed and applied as if mycorrhiza did not exist. A. Fortin invited scientists working in the field ofmycorrhiza in tropical and Mediterranean ecosystems, political deciders, and partners for development to exchange experience and to set up new strategies on mycorrhizal research in Africa. There was a large discussion about the use of mycorrhiza in agriculture and forestry in Africa. A. Bâ (Senegal) opened a session on diversity and function of ectomycorrhizal (ECM) symbioses, illustrating that Russulales and Thelephorales dominate aboveand belowground ECM fungal communities in open and rain forests in tropical Africa. Following presentations covered the role of ECM in the regeneration and functioning of tropical African forests, their potential use for ecological restoration of sites contaminated by heavy metals and the rich occurrence of edible ECM fungi in these regions (N. Onguene Awana, Cameroon; G. Kudzo Atsu, Togo; K. Sanon, Burkina Faso; M. Ducousso, France). There followed much debate about the importance of ECM fungi in forest diversity, productivity, resilience, and restoration. V. Gianinazzi-Pearson (France) introduced a session on diversity and function of arbuscular mycorrhiza (AM) by emphasizing the ecosystem services they provide to plant productivity and survival, and the necessity, for their efficient exploitation in plant production systems, to reduce chemical inputs, evaluate in situ fungal potential and plant responsiveness A. Bâ (*) IRD/LCM/LSTM, BP. 1386, Dakar, Senegal e-mail: amadou.ba@ird.fr

Do endemic species always have a low competitive ability? A test for two Mediterranean plant species under controlled conditions

Aims Many observations concerning biological and ecological differentiation between narrow endemic and widespread congeneric plant species suggest that narrow endemic species are constrained to colonize marginal habitats because of a low tolerance to competition. Despite this topic being an important issue both for understanding evolutionary processes leading to endemism and for conservation purposes, few studies have been performed to compare competitive abilities between endemic and widespread species. Here, we present two independent experiments performed under controlled conditions using two different pairs of endemic and widespread congeneric species: Centaurea corymbosa/Centaurea maculosa and Arenaria provincialis/Arenaria serpyllifolia, both endemic species occurring in rocky calcareous habitats. Methods Mature seeds of C. corymbosa and C. maculosa were sown in pots containing ramets of the common grass, Brachypodium retusum. Pots were sorted in three treatments according to grass cover (low, intermediate and high). A control treatment (without competition) was also used. Germination, seedling survival and rosette growth were followed. For the comparisons between A. provincialis and A. serpyllifolia, seeds from natural populations were first sown without a competitor. One week after germination, healthy seedlings were transplanted in pots without Brachypodium seedling (control) or containing two Brachypodium seedlings (low competition) or four seedlings (high competition). We checked the number of capsules per individual, and we harvested the biomass after capsule maturation. Important Findings Despite differences in the protocol design, results are congruent, and in both cases, endemic species are highly affected by the presence of a competitor, as are the widespread species, although we did not detect any differences between species for response to competition. The results are discussed in relation to processes leading to endemism, suggesting that the specialist model is more likely for both the study species. The present study also contributes to guidelines for the conservation of rare species in relation to landscape modification in the Mediterranean area.

Plant-specific volatile organic compound emission rates from young and mature leaves of Mediterranean vegetation

[1] The seasonality of vegetation, i.e., developmental stages and phenological processes, affects the emission of volatile organic compounds (VOCs). Despite the potential significance, the contributions of seasonality to VOC emission quality and quantity are not well understood and are therefore often ignored in emission simulations. We investigated the VOC emission patterns of young and mature leaves of several Mediterranean plant species in relation to their physiological and developmental changes during the growing period and estimated Es. Foliar emissions of isoprenoids and oxygenated VOCs like methanol and acetone were measured online by means of a proton transfer reaction mass spectrometer (PTR-MS) and offline with gas chromatography coupled with a mass spectrometer and flame ionization detector. The results suggest that VOC emission is a developmentally regulated process and that quantitative and qualitative variability is plant species specific. Leaf ontogeny clearly influenced both the VOC Es and the relative importance of different VOCs. Methanol was the major compound contributing to the sum of target VOC emissions in young leaves (11.8 ± 10.4 μg g−1 h−1), while its contribution was minor in mature leaves (4.1 ± 4.1 μg g−1 h−1). Several plant species showed a decrease or complete subsidence of monoterpene, sesquiterpene, and acetone emissions upon maturity, perhaps indicating a potential response to the higher defense demands of young emerging leaves.

Discrimination of common Mediterranean plant species using field spectroradiometry

Field spectroradiometry of land surface objects supports remote sensing analysis, facilitates the discrimination of vegetation species, and enhances the mapping efficiency. Especially in the Mediterranean, spectral discrimination of common vegetation types, such as phrygana and maquis species, remains a challenge. Both phrygana and maquis may be used as a direct indicator for grazing management, fire history and severity, and the state of the wider ecosystem equilibrium. This study aims to investigate the capability of field spectroradiometry supporting remote sensing analysis of the land cover of a characteristic Mediterranean area. Five common Mediterranean maquis and phrygana species were examined. Spectra acquisition was performed during an intensive field campaign deployed in spring 2010, supported by a novel platform MUFSPEM@MED (Mobile Unit for Field SPEctral Measurements at the MEDiterranean) for high canopy measurements. Parametric and non-parametric statistical tests have been applied to the continuum-removed reflectance of the species in the visible to shortwave infrared spectral range. Interpretation of the results indicated distinct discrimination between the studied species at specific spectral regions. Statistically significant wavelengths were principally found in both the visible and the near infrared regions of the electromagnetic spectrum. Spectral bands in the shortwave infrared demonstrated significant discrimination features for the examined species adapted to Mediterranean drought. All in all, results confirmed the prospect for a more accurate mapping of the species spatial distribution using remote sensing imagery coupled with in situ spectral information.

Antioxidant activities, total phenolics and HPLC analyses of the phenolic compounds of extracts from common Mediterranean plants

In this study, the total phenolic amounts and antioxidant activities of plant extracts obtained from some common Mediterranean plant species collected from different places in Jordan were determined. The phenolic constituents of these extracts were also determined using HPLC. The total phenolic amounts ranged from 52.8 to 876.9 mg GAE per 100 g dry material. The antioxidant activities were evaluated according to the 2,2-diphenyl-1-picrylhydrazyl radical scavenger method. Sage (Salvia officinalis) showed the highest antioxidant activity (91%), while the lowest (11.3%) was seen in parsley (Petroselinum crispum). A strong correlation (r = 0.85) between antioxidant activity and total phenolic content was found. The phenolic compounds identified by HPLC were gallic acid, protocatechuic acid, catechin, gentisic acid, chlorogenic acid, vanillic acid, syringic acid, caffeic acid, epicatechin and benzoic acid. All the investigated plants contain gallic acid, whose phenolic content ranged from 0.4 to 37.8 mg per 100 g, catechin (0.3–339.9 mg per 100 g), protocatechuic acid (0.3–41.9 mg per 100 g) and gentisic acid (0.3–35.8 mg per 100 g), while caffeic acid (0.3–2.6 mg per 100 g) was detected in six species only. These natural plant phenolics could thus be a good source of antioxidants for applications in food.

Correlations between phenolic content and antioxidant properties in twenty-four plant species of traditional ethnoveterinary use in the Mediterranean area

Context: Scientific information on antioxidant properties and phenolic content of less widely used plants can be useful. Therefore, the assessment of such properties remains an interesting and useful task, particularly for finding new sources for natural antioxidants, functional foods, and nutraceuticals.Objective: As knowledge about antioxidant properties and phenolic content of many plant species used as traditional plant remedies is limited, we determined in vitro the total antioxidant activity and the phenolic content of several plant species traditionally used for ethnoveterinary practices.Materials and methods: For 24 extracts (70% acetone) from wild and cultivated plant species traditionally used for health care of animals we determined the Trolox equivalent antioxidant capacity (TEAC) by the two assays 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the 2,2′-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS). The phenolic content was determined by the Folin Ciocalteu method.Results: Total phenolics, calculated as gallic acid equivalent (GAE), showed variation ranging from 3.18 (Allium sativum L. (Liliaceae)) to 147.68 (Pistacia lentiscus L. (Anacardiaceae)) mgGAE/g dry weight (DW). High TEAC values corresponded to high phenolic content, while plants with low antioxidant activity exhibited low total phenolic content. The TEAC determined through each assay and total phenolic content were positively correlated, R2 = 0.9152 and R2 = 0.8896, respectively, for DPPH and ABTS assay.Discussion and conclusion: These findings suggest that phenolic content could be used as an indicator of antioxidant properties. The results of this study encourage investigations on Mediterranean plant species as sources of antioxidants.

Colour, design and reward: phenotypic integration of fleshy fruit displays

The functional or structural linkage among traits [phenotypic integration (PI)] within complex structures can constrain the evolutionary response of individual traits. To analyse whether frugivores with distinct sensory ecology have shaped the patterns of fruit diversification differently, we compared PI values of fleshy fruits that are consumed by birds and mammals. We used phylogenetic comparative analyses of PI among 13 morphological, nutritional and visual fruit traits from 111 Mediterranean plant species. Results showed that morphological traits had higher PI values than nutritional and colour traits. Visual and nutritional traits show positive phylogenetic covariance, while negative covariation occurs between fruits size and nutrients. Importantly, fruits consumed by birds were relatively more integrated than fruits consumed partly or solely by mammals. Hence, we show that major groups of mutualistic frugivores can shape the covariance among some fruit traits differently and thereby influence fruit diversification.

Biological Activity and Essential Oil Analysis of Endemic Centaurea gloriosa var. multiflora Radic

Centaurea gloriosa var. multiflora Radic (Asteraceae) is a Mediterranean plant species,endemic to the Biokovo Mountain (Croatia). This work presents the very first report on phytochemical studiesof essential oil and different plant extracts of this endemic species. The volatile profile of odorous parts of theplant was analyzed by GC-MS, and n-hexane, ethanol and aqueous extracts have been examined for thecontent of total phenolic and antioxidant activity. The amount of total phenolic content was higher in aqueousextract than in n-hexane extract, and ethanol extract, respectively. As expected, extracts with a higher totalphenolic content have more prominent antioxidant and antimicrobial activity. In adddition, essential oil andwaste water after hydrodistillation were subjected to an antimicrobial assay and showed certain antimicrobialactivity.

The wettability of ash from burned vegetation and its relationship to Mediterranean plant species type, burn severity and total organic carbon content

Immediately following a wildfire, a layer of ash and charred material typically covers the ground. This layer will gradually be reduced, being redistributed by rainfall, wind or animals, by partial dissolution and by incorporation into the soil. Ash can increase or decrease the post-fire runoff and erosion response, depending upon the soil and ash properties and the ash thickness. One aspect of ash that has remained unknown and which may affect the variability in the hydrological response of the burned soil is its wettability. This study examines the wettability of ash using the Water Drop Penetration Time (WDPT) test, its relationship with total organic carbon (TOC) content and colour, and its effects when incorporated into the soil. Ash samples ( n = 48) were taken from five wildfires in the Mediterranean basin encompassing a range of burn severities. Additional ash material was generated from exposing plant leaves ( Rosmarinus officinalis, Pinus halepensis and Quercus coccifera) to specific temperatures in a muffle furnace (200–700 °C). Selected laboratory ash types were also mixed with wettable and water repellent soil material to assess their effect on soil wettability. Over 30% of ash samples from the wildfire sites exhibited water repellency (WR), with WDPT levels ranging from low to extreme. This variability appears to be related to differences in fire severity, combustion completeness of the biomass, vegetation type and subsequent rainfall events. The laboratory-generated ash exhibited a greater frequency and persistence of water repellency at lower furnace temperatures (200–300 °C), with ash from R. officinalis being generally less water repellent than that derived from the other two species. The water repellency levels of ash correlated well with TOC (r = 0.80), whereas neither of these parameters correlated very well with ash colour (r = 0.57 for TOC and r = 0.59 for WR). This suggests that ash colour, which is widely used as a parameter in classifying burn severity in the field, may not necessarily be a very accurate indicator. Adding water repellent ash to wettable soil induced WR, whereas the addition of wettable ash to water repellent soil had the opposite effect. A wetting–drying cycle can reduce the water repellency of a soil–ash mixture. There were substantial differences between wildfire- and laboratory-generated ash in terms of organic carbon content and colour, suggesting that the combustion conditions in a furnace may not adequately represent those in wildfires. In contrast to what is generally assumed, our findings demonstrate that ash from vegetation fires can be water repellent. This is likely to have implications for runoff responses and nutrient fluxes not only when ash is present on the ground surface, but also following its redistribution and incorporation into the soil.

Genome size unaffected by moderate changes in climate and phosphorus availability in mediterranean plants

Nuclear DNA amount has been assessed in a set of 6 Mediterranean plant species including subshrubs, shrubs and trees ( Dorycnium pentaphyllum Scop., Erica multiflora L., Fumana ericoides (L.) Webb, Globularia alypum L., Pinus halepensis Mill and Rosmarinus officinalis L. ). Genome size values have been assessed by flow cytometry from plants growing in their natural habitats, in plots with a particular experimental design to measure the effects of drought and warming and also with different phosphorus (P) concentration in soil. 2C values have been fairly constant in all the species studied under all conditions. These results, which provide first records of DNA content in all the studied species except for P. halepensis , suggest that moderate changes in climate such as a 0.73°C warming or a drought consisting of 19% decrease in soil moisture on an average of 7 years and the consequent changes in the soil availability of such an essential element as P (ranging from 80 to 160 g/g) do not affect genome size stability, at least not by producing rapid and significant variations. Key words : C-value, drought, Mediterranean plants, nuclear DNA amount, phosphorus, warming.

Encroachment of upland Mediterranean plant species in riparian ecosystems of southern Portugal

Riparian ecosystems have unique biodiversity, are highly sensitive to disturbance and anthropogenic influence. As world water resources become scarcer, scientists predict greater competition among species for water resources. Indeed, increased encroachment of upland plants into the riparian zone is already occurring, irreversibly changing riparian plant communities. Since semi-arid regions such as Mediterranean-type ecosystems are likely to follow this same trajectory, assessing the contributions of riparian versus upland (sclerophyllous) plants to community composition is important. A survey of seventy 2 km-long riparian transects on the Sado and Guadiana watersheds in southern Portugal assessed (1) the woody riparian plant community composition, (2) how much richness is due to strictly riparian plants versus sclerophyllous upland plants, and (3) which combinations of biotic and abiotic factors allow higher species richness in the strictly riparian, sclerophyllous, and overall plant communities. The survey detected 53 different woody plant species (28 endemic) across all communities. Riparian community richness was on average 16 species, seven of which were strictly riparian and the remainder being sclerophyllous, exotic species or fruit trees. Sclerophyllous plant species occurred consistently across sampling units (90% of transects). On average, 46% of the total woody plant community richness was due to strictly riparian plants and 28% was due to sclerophyllous plants. Community richness was positively affected by the area of shrubs in the riparian zone and by the absence of human activities and goats. Surrounding landscape pattern only affected the strictly riparian plant richness. These results suggest that natural and human-mediated disturbances in riparian ecosystems create gaps and clearings for which riparian and sclerophyllous plants compete. Establishment success seems to be related to the propagule pressure of the neighbouring landscape, its diversity and density, as well as the presence of herbivores. Preserving strictly riparian plants, removing exotic species, preventing grazing, and promoting riparian values (recreation, aesthetics and the provision of ecosystem services) will aid the future conservation of the unique biodiversity of riparian ecosystems.

Analysis and origins of volatile organic compounds smoke from ligno-cellulosic fuels

This paper investigates relationships between the emission of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) from five representative Mediterranean plant species and bio-polymers extracted from the leaves. The experimental results showed that there are differences in bio-polymer composition according to the species. Erica arborea is the fuel that contains most of holocellulose (cellulose and hemicellulose) and Pinus laricio is the fuels containing most of lignin. The plant samples were burned using an epiradiator. Automated Thermal Desorption–Gas Chromatography–Flame Ionization Detector (ATD–GC–FID) and Automated Thermal Desorption-Gas Chromatography/Mass Spectrometry (ATD–GC/MS) analysis identified 71 compounds, the compounds emitted from ligno-cellulosic fuel are VOCs and SVOCs. These emissions represented from 1164.5 ± 163.4 to 1437.9 ± 244.0 μg g −1 dw of combustible fuel. There are not significant differences in the total emissions according to the species, but differences in the proportions of lignin, cellulose, hemicellulose and extractives led to quantitative variations in the class compounds present in the smoke. Partial Redundancy Analysis (RDA) highlighted presence of strong relationships between the emissions of some subfamilies of compounds and the proportions of the various bio-polymers.

The Potential of Biodiesel Production from Fatty Acid Methyl Esters of Some European/Mediterranean and Cosmopolitan Halophyte Seed Oils

Abstract Biodiesel fuel, mainly produced from edible vegetable oils, has been proposed as a renewable substitute for petroleum diesel. However, there is growing concern about its role in rising food prices, accelerating deforestation, and displacing existing agricultural production. Moreover, given the progressive shortages of freshwater resources and arable land, a major target of investigations is to evaluate the potential utilization of promising salt-tolerant halophytic non-food crops for the sustainable production of oil-rich biomass, which will be converted to fuel. In this paper, an attempt has been made to look into the potential of the exploitation of native halophytic plants in European and Mediterranean arid or semi-arid lands that can prosper in seawater or brackish waters for diesel production in Europe. Fatty acid (FA) profiles of seed oils of 37 European and Mediterranean halophytic plant species including some of cosmopolitan distribution were examined. The saponification number, iodine value (IV), cetane index (CI), and gross heat of combustion of FA methyl esters (FAMEs) of oils were calculated from reported FAMEs compositions, and they varied from 165.3 to 193.3, from 71.8 to 173.7, from 35.9 to 60.0, and from 39.86 to 40.41 MJ/kg, respectively. FA seed oil content and composition, IV, CI, linolenic acid ME, and polyunsaturated ME (with ≥4 double bonds) contents were used to predict the quality of FAME of oil for use as biodiesel, according to EN 14214 European standard. Crithmum maritimum and Crambe maritima, having more than 30 % fixed oil in their seeds, were found most suitable as alternative vegetable oil sources for the production of biodiesel.

Interaction of climate, demography and genetics: a ten-year study of Brassica insularis, a narrow endemic Mediterranean species

Long-term demographic surveys, needed to obtain accurate information on population dynamics and efficiently manage rare species, are still very scarce. Matrix population models are useful tools to identify key demographic transitions and thus help setting up conservation actions. Furthermore, the combination of ecological, demographic and genetic data is likely to improve the identification of the threats acting upon populations and help conservation decisions. In this paper we illustrate the power of this approach on Brassica insularis, a Mediterranean endemic plant species, rare and endangered in Corsica (France). In four populations of this species, a long-term demographic survey (2000-2009), genetic analyses (in 2000 and 2009) and survey of ecological variables (climatic variables, competition and herbivory) were performed. By using both deterministic and stochastic matrix model analyses, we assessed the viability of each population and tested for both spatial and temporal variations in demographic vital rates. Populations exhibited differing demographic behaviours and environmental stochasticity occurred in populations. Significant correlations between climatic variables and vital rates were detected. Stochastic simulations suggested that three out of the four populations studied might present a high risk of extinction on the short-term and should actively be managed, or at least surveyed. It could be, however, that two of these populations are experiencing density-dependent regulation, rather than being declining. Microsatellite diversity was slightly reduced in a single population and similar in the three others, consistently with expectations based on population census size and geographic area, as well as with diversity at the S-locus observed in 2000. The combination of all data led to specific recommendations for managing each population. We discuss the implications for conservation of such a general approach.