Cistus Salviifolius Research Articles

Leaf Trait Variability and CSR Strategy Shifts in Mediterranean Woody Species along an Edaphic Gradient

Plant species in Mediterranean ecosystems are expected to exhibit diverse responses to environmental stresses such as climate aridity and challenging soil conditions by adopting various functional strategies. However, intraspecific variability at the local scale has received insufficient attention in the study of CSR strategies. This study aims to evaluate intraspecific variability in leaf traits and CSR strategies of seven woody species growing on ultramafic and non-ultramafic soils in the Beni Bousera region of Northern Morocco. We first conducted a physicochemical analysis to assess differences in soil composition between the two sites. Subsequently, we measured leaf fresh weight, leaf dry weight, and leaf area and calculated CSR strategies for 10 individuals per species. The results revealed significant differences between the two soil types, primarily driven by a moderate serpentine effect characterized by a Ca:Mg ratio <1 in the ultramafic site, along with distinct soil texture. In response to these challenging conditions, we observed substantial intraspecific variability in leaf traits, accompanied by shifts in CSR strategies for certain species. At the ultramafic site, Quercus coccifera adopted an S strategy, while Cistus salviifolius exhibited an S/SC strategy. Lavandula stoechas and Teucrium fruticans displayed notable interindividual variability, whereas Cistus atriplicifolius, Phillyrea latifolia, and Erica arborea maintained consistent strategies across both sites. Our research contributes to the enrichment of CSR databases and highlights the applicability of the CSR strategy framework at the local, intraspecific level, offering a valuable foundation for future ecological studies and plant conservation efforts. Moreover, investigating intraspecific variability in leaf traits and CSR strategies enhances our understanding of plant adaptation mechanisms in extreme environments such as Mediterranean serpentine soils.

Philaenus tesselatus (Hemiptera: Aphrophoridae), the main potential vector of Xylella fastidiosa in Morocco: seasonal abundance, phenology and host-plant colonization by nymphs

Summary The bacterium Xylella fastidiosa presents a potential risk to the Moroccan flora, particularly for the citrus, olive, almond and grapevine industries. Philaenus tesselatus, the meadow spittlebug, is the most important Moroccan spittlebug, though recorded with uneven occurrence and considered to be the main potential insect vector of X. fastidiosa. A three-year field survey (2019 to 2021) was conducted at three sites in the provinces of Larache and Kenitra in northwestern Morocco, to study seasonal abundance, phenology and host-plant colonization by nymphs. Philaenus tesselatus is a univoltine species. Nymphs occurred in groundcover from end of mid-March to mid-May, with abundance peaking between end of March and mid-May. Emergence of teneral adults occurred between April and May, depending on the year. Adults were present on ground vegetation from March until early August, with the highest abundances surveyed by sweep net in April, and occurred in canopy in low abundance between the end of May and mid-September, depending on site. Both nymphal and adult abundances were significantly higher in Larache than at the other two sites. Philaenus tesselatus, the meadow spittlebug, is a polyphagous species, recorded on nine botanical families of host plant species including Asteraceae, Poaceae, Fabaceae, Polygonaceae, Apiaceae, Primulaceae, Urticaceae, Papaveraceae and Malvaceae, and 37 host plant species, of which 29 were identified. The Asteraceae were best represented. Carduus pycnocephalus, Vulpia geniculata, Anthoxanthum odoratum and Cistus salviifolius were the most suitable for this spittlebug. Avena barbata, L. foemina, Scolymus hispanicus and S. oleraceus were dominant in the herbaceous layer. Philaenus tesselatus preferred to feed on the mid-section of the host plants. A single foam can host zero to five individuals, but foams with one or two nymphs were most frequent. Implications of our findings for the setting up of a survey program to control X. fastidiosa and its vectors in case the bacterium is introduced to Morocco are discussed.

Short range shifts in plant physiological responses to induced water stress: Experimental evidence of intraspecific trait variability differentiating neighbouring Mediterranean plant populations

Mediterranean plants are facing increased periods of drought, potentially jeopardizing their survival. Despite the known influence of intraspecific variability on plants’ responses to the environment, most studies focus on differences between species and overlook short distances. Following the observation of three nearby populations of Quercus ilex and Cistus salviifolius inheriting different sets of drought-related functional traits in common garden, we tested if these populations could perform differently under water stress. We observed drought responses on plantlets from both species, measuring key physiological traits such as gas exchanges and spectrometric indexes. Our results show similar responses from populations of C. salviifolius while Q. ilex had high intraspecific variability, with increased drought-resistance in plants hailing from dry provenances, reflected by improved water use efficiency, photosynthetic capacity, and reduced metabolic response to stress. These observations support the idea that, despite the short distances, neighbouring plant populations can adapt differently to drought, changing the way they withstand climate and its changes.

Correlation Between the Amount of Total Phenolic Contents and Antioxidant Activity of Mediterranean Shrubs: Are Phenols a Good Indicator of the Antioxidant Activity of These Species?

Background:: Cells generate reactive oxygen species (ROS), which cause oxidative stress. Such stress is counteracted by a complex antioxidant system, which includes molecules of the secondary metabolism of plants, mainly phenols. Several studies attribute the antioxidant activity of a species to these compounds, although, in other studies, this relationship is not clear. Objective:: The aim of this study was to determine whether the amount of total phenols is a good indicator of the antioxidant activity of a species. Methods:: The present study quantified the total phenols and antioxidant activity measured by DPPH and ABTS methods of 18 species of Mediterranean scrubs and established the correlation between these two parameters. Results:: The obtained results showed that there was a wide variability in the content of phenols among the analyzed species, with Cistus salviifolius and Nerium oleander presenting the largest and smallest amount of total phenols, respectively (0.043 and 0.004 gallic acid equivalent (mg/mg dw)). A cluster analysis differentiated these species into two groups with significantly different amounts of phenols. The species that constitute Group I presented an average amount of 0.029 gallic acid equivalent (mg/mg dw), and that of the species of Group II was 0.011±0.003 gallic acid equivalent (mg/mg dw). The relationship between the antioxidant activity quantified in each species and its content of total phenols showed a positive and significant correlation; however, when considering the two groups of species, the significant correlation between these parameters depends on the species group, the extract concentration used, and the method employed to quantify the antioxidant activity. Conclusion:: These results indicate that it would not be correct to generalize that there is a significant correlation between the amount of total phenols and the antioxidant activity. Therefore, total phenol content cannot be used as a single indicator of the antioxidant activity of a species.

Biosynthesis and Characterization of Silver Nanoparticles Mediated by Cistus salviifolius L. and Ferula communis L. Extracts and Evaluation of Their Antioxidant, Antibacterial, and Cytotoxic Potentials

Biosynthesis and Characterization of Silver Nanoparticles Mediated by Cistus salviifolius L. and Ferula communis L. Extracts and Evaluation of Their Antioxidant, Antibacterial, and Cytotoxic Potentials

Study of Antibacterial Activity of Cistus salviifolius L. extracts (Cistaceae) against Agrobacterium tumefaciens, Erwiniacarotovora, Escherichia coli and Staphylococcus aureus

The objective of this study was to assess antibacterial activity in vitro of crude extracts from leaves of Cistus salviifolius on pathogenic bacteria. Screening of antibacterial activity of ethanol, methanol, distilled water and acetone extracts with three concentrations of each one (5, 10 and 15)g/100ml of Cistus salviifoliusleaves were estimated against four types of pathogenic bacteria (Agrobacterium tumefaciens, Erwinia carotovora, Escherichia coli and Staphylococcus aureus) were investigatedafter incubation at 37°C for 24hrs by using Well Diffuion Method employing 100µL of each sample. The antibacterial activity is determined from the evaluation of the zone of inhibition. Antibaterial activity of all extracts was compared with that for a six of antibiotics by using antibiograme test. All extracts of Cistus salviifolius showed clear antibacterial activity against pathogenic bacteria, which this activity wasenhanced with the increasing of concentrations belongs to them. The latest concentration 15g/100ml of all extracts gave highest activity againsttested strains. In this research three replications were done. In this study, it was found that ethanol extract of Cistus salviifolius showed the highest inhibition zone against Agrobacterium tumefaciens with 27.35 mm diameter at concentration 15g/100ml. The effect of Ciprofloxacin CIP 5µg against Agrobacterium tumefacienswas better than the effect of Nitrofurantion F 300µg and Gentamicin CN 10µg. A resist of pathogenic bacteria to Oxacillin OX 1µg and Cefoxitin FOX 30µg was noticed. Fusidic Acid FD 10µg only effected on Erwinia carotovora with inhibition zone (15.16 mm).

Screening of Antimicrobial, Antibiofilm, and Cytotoxic Activities of Some Medicinal Plants from Balıkesir Province, Türkiye: Potential Effects of Allium paniculatum Flower.

Plant extracts are important natural resources that may have antimicrobial and antibiofilm effects against pathogens. This study was conducted to investigate the in vitro antimicrobial activities of methanol extracts of some medicinal plants (Achillea nobilis subspecies neilreichii (A. Kern.) Velen., Aetheorhiza bulbosa (L.) Cass, Allium paniculatum L, Asphodelus aestivus Brot., Ballota nigra L., Cistus laurifolius L., Cistus salviifolius L., Dioscorea communis (L.) Caddick and Wilkin, Galium verum L., Hypericum triquetrifolium Turra, Paliurus spina-christi Mill., Primula vulgaris Huds. subspecies rubra (Sm.) Arcang., Ranunculus arvensis L. and Teucrium polium L.) from Balıkesir province in Türkiye. Preliminary antimicrobial activity screening was conducted for all extracts. Antibiofilm activity studies were conducted on mature Candida albicans biofilms. Moreover, the cytotoxicities of A. paniculatum flower extract on A549 and Vero cell lines were determined using a colorimetric tetrazolium-based assay. A. paniculatum flower, P. vulgaris root, C. laurifolius, C. salviifolius, and A. nobilis displayed good activity [minimum inhibitory concentrations (MIC): 9.75, 156, 312, 312 and 312 μg/mL, respectively] against C. albicans American Type Culture Collection 10231. Biofilm studies were conducted on these plant extracts. The methanol extract of A. paniculatum flower decreased the number of C. albicans [colony-forming unit (CFU)/mL] in mature biofilm statistically at 32 x MIC and higher concentrations (p < 0.01). A. paniculatum flower extract had a cytotoxic effect (killing more than 50% of cells) at high concentrations, and its effect on Vero cells was similar to that on A549 cells. This study demonstrated the importance of the methanol extract of A. paniculatum flower as a natural alternative against C. albicans infections, including biofilms.

Tackling local ecological homogeneity: Finding intraspecific trait variability in local populations of Mediterranean plants.

Local homogeneity, in ecology, is the often undisclosed assumption that variability within populations is negligible or mostly distributed evenly. In large areas, this can lead to the aggregation of different populations without regard for their unique needs and characteristics, such as drought sensitivity and functional trait distributions. Here, we discuss whether this assumption can be justified, and we hypothesize that discerning the source of variation between plasticity and adaptation could be a feasible approach to formulate an informed decision. We test this hypothesis on plants, resorting to a common garden experiment to determine the source of variation of several plant functional traits at a local scale (~60 km) of three wild species: Quercus ilex, Pistacia lentiscus, and Cistus salviifolius. Individuals of each species were sourced from three key sites chosen along a local aridity gradient. Our approach led to the rejection of the local homogeneity assumption for Q. ilex and C. salviifolius at this scale due to the adaptive divergence observed among neighboring populations. This case study provides evidence that addressing local homogeneity can highlight diverging populations in a relatively simple way. We conclude that gathering empirical evidence on intraspecific variability is a feasible approach that can provide researchers with solid bases to decide whether to adopt the local homogeneity assumption or not.

Climatic variations along an aridity gradient drive significant trait intraspecific variability in Mediterranean plant species

Drought represents one of the main sources of stress for plants in the Mediterranean region, and climate change is further escalating this stress. Plants can employ several response strategies to cope with stress, reflected in the adoption of specific Plant Functional Traits (PFTs). Trait-based approaches commonly meet three issues: they may overlook Intraspecific Variability (ITV), they could focus on large spatial scales, or they could focus on few traits. Here we present evidence that it’s possible to observe ITV in morphological and anatomical trait syndromes between three local populations of Phillyrea latifolia, Pistacia lentiscus, and Quercus ilex, distributed along an aridity gradient. Thicker, physiologically expensive leaves and lower heights found in the drier sites mainly conform to drought-resistance strategies, while trait spectra from Cistus salviifolius were found not to vary significantly across sites. Thus, the amount of ITV observable at a local scale varies between species. We conclude that climate can easily drive a significant amount of ITV for several species, reflected in their trait spectra, among plant populations that are geographically close to each other. This highlights the importance of local environmental variability and implies that different populations hailing from nearby sites might respond differently to climate change.

Development of a Fuel Model for Cistus spp. and Testing Its Fire Behavior Prediction Performance

This paper presents the development of a fuel model that can describe fuel situations in areas dominated by Cistus spp. (rockrose) in Greece. In order to obtain the necessary fuel data, thirty (30) 1 m2 plots were destructively sampled in phryganic areas dominated by Cistus creticus, Cistus parviflorus, and Cistus salvifolius in western Greece. To develop the fuel model for Cistus spp., field measurements were supplemented with published parameter values for Cistus salvifolius. The resulting fuel model (with a height of 9.44 cm) is suitable for describing Cistus spp.-dominated phryganic areas of relatively low vegetation height in southeastern Europe. Once developed, the fuel model was inputted into the BehavePlus system to produce surface fire rate of spread predictions (ROSpred, m·min−1), which were then compared to 21 surface fire ROS field observations (ROSobs) obtained from wildfires or prescribed burns in areas covered by Cistus spp. It was found that the ROS for the Cistus spp. fuel model significantly underpredicted the actual ROS. A statistically significant linear regression equation was developed to mathematically describe the relationship between the predicted and observed ROS. This equation can be used to adjust BehavePlus predictions to more accurately reflect the real-world fire behavior for this fuel type.

Functional Groups Response to Water Deficit in Mediterranean Ecosystems.

Enhanced drought, more frequent rainfall events and increased inter-annual variability of precipitation are the main trends of climate expected for the Mediterranean. Drought is one of the most important stressors for plants and significantly impacts plant communities causing changes in plant composition and species dominance. Through an experiment under controlled conditions, we assessed the response of Mediterranean species from different functional groups (annual grass, annual forb, annual legume, and perennial shrub) to moderate and severe water deficit. Changes in plant traits (leaf dry matter), biomass and physiology (water status, photosynthesis, pigments, and carbohydrate) were evaluated. The studied species differed in their response to water deficit. Ornithopus compressus, the legume, showed the strongest response, particularly under severe conditions, decreasing leaf relative water content (RWC), pigments and carbohydrates. The grass, Agrostis pourreti and the forb, Tolpis barbata, maintained RWC, indicating a higher ability to cope with water deficit. Finally, the shrub, Cistus salviifolius, had the lowest response to stress, showing a higher ability to cope with water deficit. Despite different responses, plant biomass was negatively affected by severe water deficit in all species. These data provide background for predicting plant diversity and species composition of Mediterranean grasslands and Montado under climate change conditions.

Efficacy of Two Moroccan Cistus Species Extracts against Acne Vulgaris: Phytochemical Profile, Antioxidant, Anti-Inflammatory and Antimicrobial Activities.

The genus Cistus L. (Cistaceae) includes several medicinal plants growing wild in the Moroccan area. Acne vulgaris (AV) is a chronic skin disorder treated with topical and systemic therapies that often lead to several side effects in addition to the development of antimicrobial resistance. Our study aimed to investigate the bioactivity of extracts of two Moroccan Cistus species, Cistus laurifolius L. and Cistus salviifolius L., in view of their use as potential coadjuvants in the treatment of mild acne vulgaris. Targeted phytochemical profiles obtained by HPLC-DAD and HPLC-ESI/MS analyses and biological activities ascertained by several antioxidants in vitro chemical and cell-based assays of the leaf extracts. Moreover, antimicrobial activity against Gram-positive and Gram-negative bacteria, and Candida albicans was evaluated. Analyses revealed the presence of several polyphenols in the studied extracts, mainly flavonoids and tannins. Cistus laurifolius L. and Cistus salviifolius L. possessed good biological properties and all extracts showed antibacterial activity, particularly against Staphylococcus aureus, S. epidermidis, and Propionibacterium acnes, identified as the main acne-causing bacteria. The results suggest that examined extracts are promising agents worthy of further studies to develop coadjuvants/natural remedies for mild acne treatment.

Antimicrobial Properties of Essential Oils Obtained from Autochthonous Aromatic Plants.

The aim of this work was to determine the antimicrobial activity of the essential oils of six plants widely distributed in the Dehesa of Extremadura, such as Calendula officinalis, Cistus ladanifer, Cistus salviifolius, Cistus multiflorus, Lavandula stoechas, and Rosmarinus officinalis. The content of total phenolic compounds (TPC) and the antimicrobial activity of the essential oils against pathogenic and spoilage bacteria and yeasts as well as aflatoxin-producing molds were determined. A great variability was observed in the composition of the essential oils obtained from the six aromatic plants. The Cistus ladanifer essential oil had the highest content of total phenols (287.32 ppm), followed by the Cistus salviifolius essential oil; and the Rosmarinus officinalis essential oil showed the lowest amount of these compounds. The essential oils showed inhibitory effects on the tested bacteria and also yeasts, showing a maximum inhibition diameter of 11.50 mm for Salmonella choleraesuis and Kregervanrija fluxuum in the case of Cistus ladanifer and a maximum diameter of 9 mm for Bacillus cereus and 9.50 mm for Priceomyces carsonii in the case of Cistus salviifolius. The results stated that antibacterial and antiyeast activity is influenced by the concentration and the plant material used for essential oil preparation. In molds, aflatoxin production was inhibited by all the essential oils, especially the essential oils of Cistus ladanifer and Cistus salviifolius. Therefore, it can be concluded that the essential oils of native plants have significant antimicrobial properties against pathogenic and spoilage microorganisms, so they could be studied for their use in the industry as they are cheap, available, and non-toxic plants that favor the sustainability of the environment of the Dehesa of Extremeña.

Phytochemistry and Antihyperglycemic Potential of Cistus salviifolius L., Cistaceae.

Cistus salviifolius has been previously reported as a traditional remedy for hyperglycemia. However, the plant has been scarcely investigated from scientific point of view. Thus, the aim was to examine the chemical composition and to evaluate its antioxidant and antihyperglycemic potential in vitro. Aqueous and ethanolic extracts were evaluated for total phenolic, tannin, and flavonoid content using spectrophotometric methods. Detailed chemical characterization was performed by high-performance liquid chromatography (HPLC-DAD). The volatile organic compounds (VOCs) profile was assessed by gas chromatography technique. The potential in diabetes treatment was evaluated through tests of free radicals neutralization, inhibition of lipid peroxidation process, and test of ferric ion reduction; activity in tests of inhibition of α-amylase, α-glucosidase and dipeptidyl peptidase-4 was also evaluated. High content of phenolics (majority being tannins) was detected; detailed HPLC analysis revealed high content of gallic acid, followed by rutin, chlorogenic and caffeic acids. The VOCs analysis determined sesquiterpene hydrocarbons and oxygenated sesquiterpenes as the main groups of compounds. The assays classified extracts as potent neutralizers of 2,2-diphenyl-1-picrylhydrazil and nitroso radicals formation and potent inhibitors of α-amylase and α-glucosidase. In conclusion, Cistus salviifolius represents a rich source of phenolics and essential oil with sesquiterpenes. The established results suggested its promising antioxidant and antihyperglycemic activities.

The Allelopathic Effects of Two Species of Cistus Genus on Germination and Root Length of Ceratonia Siliqua L.

This study examines the allelopathic effects of Cistus incanus (synonym C. villosus) L. and Cistus salviifolius L. on the germination and the root length of Ceratonia siliqua. Six aqueous extracts were prepared for both species by soaking fresh leaves in cold water, boiling leaves and leaving for 24 hours, and grinding dried leaves. The result suggests that the germination percentage was slightly affected by extract concentration regardless of the type of extraction since F-value and P-value at 0.05 confidence level were 2.93 and 0.043 respectively. However, root length showed a significant response to the type of extraction, extract concentration, and interaction between both factors as F-values reached 6.3, 12.4, and 2.4 respectively. LSD test showed the response of seeds germination was inverse with the increase of concentration. In addition, it showed that the extracts of dried leaves were higher in root inhibition than the extracts of fresh leaves. The interaction effect reached its highest values when comparing the dried leaves’ extract to the freshly soaked ones, even for the same concentrations. In conclusion, seeds of c. siliqua were able to easily start germination because the nutrition compounds needed were available in the endosperm, and the media supported them just by moisture for establishment. While for root length, the root tissue absorbed extra quantities of the inhibiting agents from media leading to failure or weakness in root development.

Molecular Characterization of Gene-Mediated Resistance and Susceptibility of ESKAPE Clinical Isolates to Cistus monspeliensis L. and Cistus salviifolius L. Extracts.

Background Multidrug resistance (MDR) and extensively drug-resistant (XDR) are now the biggest threats to human beings. Alternative antimicrobial regimens to conventional antibiotic paradigms are extensively searched. Although Cistus extracts have long been used for infections in traditional folk medicines around the world, their efficacy against resistant bacteria still needs to be elucidated. We aim to investigate the antibiotic susceptibility profiles of clinical strains Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae (acronym “ESKAPE”), and their resistance mechanisms by PCR, as well as their sensitivity to C. monspeliensis (CM) and C. salviifolius (CS) methanol extracts and their fractions. Methods Antibiotic susceptibility profile and resistance mechanism were done by antibiogram and PCR. Fractions of CM and CS were obtained using maceration and Soxhlet; their antibacterial activities were evaluated by determining inhibition zone diameter (IZD), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). Results Results revealed that all strains were XDR except S. aureus, which was MDR. The PCR indicates the presence of gene-mediated resistance (blaCTX-M, blaSHV, blaOXA-48, blaNDM, blaOXA-51, blaOXA-58, blaIMP, blaVIM, and blamecA). Also, maceration was slightly better for bioactivity preservation. Overall, the extracts of CM (IZD = 20 mm, MIC = 0.01 mg/mL) were more active than those of CS. All extracts inhibited MRSA (methicillin-resistant Staphylococcus aureus) and ERV (Enterococcus faecium Vancomycin-Resistant) with interesting MICs. The ethyl acetate fraction manifested great efficacy against all strains. Monoterpene hydrocarbons and sesquiterpenes oxygenated were the chemical classes of compounds dominating the analyzed fractions. Viridiflorol was the major compound in ethyl acetate fractions of 59.84% and 70.77% for CM and CS, respectively. Conclusions The superior activity of extracts to conventional antibiotics was seen for the first time in the pathogens group, and their bactericidal effect could be a promising alternative for developing clinical antibacterial agents against MDR and XDR ESKAPE bacteria.

Insight into Cistus salviifolius extract forpotential biostimulant effects in modulating cadmium-induced stress in sorghum plant.

The main aim of the current study was to investigate the role of Cistus salviifolius leaves extract (CSE) in alleviating the toxic effect of cadmium (Cd) in sorghum (Sorghum bicolor) plants. The plants exposed to Cd (200µM) exhibited limited growth, reduced biomass, and chlorophyll content compared to unstressed ones. Nevertheless, supplementation of CSE restored the negative effect of Cd and increased biomass and pigment content. CSE also increased the activities of antioxidant enzymes such as superoxide dismutase (SOD), isocitrate dehydrogenase (ICDH), glutathione peroxidase (GPx), glutathione reductase (GR), and Glutathione-S-Transferase (GST). Furthermore, supplementation of CSE decreased lipid peroxidation and further increased the content of soluble sugar and amino acid. We also found that CSE has a promising effect in modulating the perturbations of carbon and nitrogen metabolism in sorghum plants under Cd stress by examining several carbon-nitrogen enzyme activities: phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (NAD-MDH), glutamine synthase (GS), glutamate dehydrogenase (GDH), and aspartate aminotransferase (AAT). Overall, our results confirm that the application of CSE can be a promising mechanism to overcome the negative effects of Cd stress in sorghum plants.

Fire and summer temperatures interact to shape seed dormancy thresholds.

Background and AimsIn Mediterranean ecosystems, the heat shock of wildfire disrupts physical seed dormancy in many plant species. This triggers germination in the post-fire environment where seedling establishment is optimal due to decreased competition and increased resource availability. However, to maintain the soil seed bank until a fire occurs, the minimum heat capable of breaking seed dormancy (i.e. the lower heat threshold) must be above the maximum temperatures typically observed in the soil during the summer. We therefore hypothesized that summer temperatures have shaped heat requirements for physical dormancy release. Specifically, we predicted that seeds from populations growing under warmer summers will have higher values of the lower heat threshold.MethodsTo evaluate this prediction, we collected seeds from two Cistus species in 31 populations (20 Cistus albidus and 11 Cistus salviifolius) along a climate gradient of summer temperatures on the eastern coast of Spain. For each population, seeds were treated to 10 min heat shocks, from 30 to 120 °C in 5 °C increments (19 treatments), to simulate increasing heat doses from summer to fire-related temperatures. Seeds were then germinated in the lab.Key ResultsFor all populations, maximum germination was observed when applying temperatures associated with fire. Lower heat thresholds varied among populations, with a positive relationship between summer temperatures at seed population origin and the heat dose required to break dormancy.ConclusionsOur results suggest that fire drives maximum dormancy release for successful post-fire germination, while summer temperatures determine lower heat thresholds for ensuring inter-fire seed bank persistence. Significant among-population variation of thresholds also suggests that post-fire seeder species have some potential to modify their dormancy release requirements in response to changing climate.

The Potential of Cistus salviifolius L. to Phytostabilize Gossan Mine Wastes Amended with Ash and Organic Residues.

The São Domingos mine is within the Iberian Pyrite Belt, a mining district with large concentrations of polymetallic massive sulfide deposits. Mine waste heaps are considered extreme environments, since they contain high total concentrations of potentially hazardous elements (PHE), which contribute to inhibiting the development of most plants. Autochthonous plant species, such as Cistus salviifolius L., are able to grow naturally in this degraded environment, and may contribute to minimizing the negative chemical impacts and improving the landscape quality. However, the environmental rehabilitation processes associated with the development of these plants (phytostabilization) are very slow, so the use of materials/wastes to improve some physicochemical properties of the matrix is necessary in order to speed up the process. This work studied the effectiveness of the phytostabilization with C. salviifolius of gossan mine wastes from the mine of São Domingos amended with organic and inorganic wastes in order to construct Technosols. The mine wastes have an acid pH (≈3.5), high total concentrations of PHE and low concentrations of organic C and available nutrients. The best vegetative development occurred without visible signs of toxicity in the Technosols containing a mixture of agriculture residues. These treatments allowed the improvement of the soil-plant system providing a better plant cover and improved several chemical properties of mine wastes, helping to speed up the environmental rehabilitation.

Spectral-Based Monitoring of Climate Effects on the Inter-Annual Variability of Different Plant Functional Types in Mediterranean Cork Oak Woodlands

Using remotely sensed data to estimate the biophysical properties of vegetation in woodlands is a challenging task due to their heterogeneous nature. The objective of this study was to assess the biophysical parameters of different vegetation types (cork oak trees, shrubs and herbaceous vegetation) in cork oak woodland through the analysis of temporal trends in spectral vegetation indices (VIs). A seven-year database (from 2011 until 2017) of in situ observations collected with a field spectroradiometer with a monthly basis was used and four VIs were derived, considered as proxies for several biophysical properties of vegetation such as biomass (Normalized Difference Vegetation Index—NDVI); chlorophyll content (MERIS Terrestrial Chlorophyll Index-MTCI), tissue water content (Normalized Difference Water Index—NDWI) and the carotenoid/chlorophyll ratio (Photochemical Reflectance Index—PRI). During the analyzed period, some key meteorological data (precipitation, temperature, relative air humidity and global radiation) were collected for the study site, aggregated at three different time-lags (short period (30 d), medium period (90 d) and hydrological period (HIDR)), and their relationship with VIs was analyzed. The results showed different trends for each vegetation index and vegetation type. In NDVI and NDWI, herbaceous vegetation showed a highly marked seasonal trend, whereas for MTCI, it was the cork oak and Cistus salvifolius, and for PRI, it was Ulex airensis that showed the marked seasonal trend. Shrubs have large differences depending on the species: the shallow-rooted Cistus salvifolius showed a higher seasonal variability than the deep-rooted Ulex airensis. Our results revealed the importance of temperature and precipitation as the main climatic variables influencing VI variability in the four studied vegetation types. This study sets up the relationships between climate and vegetation indices for each vegetation type. Spectral vegetation indices are useful tools for assessing the impact of climate on vegetation, because using these makes it easier to monitor the amount of “greenness”, biomass and water stress of vegetation than assessing the photosynthetic efficiency. Proximal remote sensing measurements are fundamental for the correct use of remote sensing in monitoring complex agroforest ecosystems, largely used to inform policies to improve resilience to drought, particularly in the Mediterranean region.