Environmental control of terpene emissions from Cistus monspeliensis L. in natural Mediterranean shrublands

The large amount of volatile organic compound (VOC) emitted by vegetation modifies air quality contributing to both tropospheric ozone and secondary organic aerosol production. A better understanding of the factors controlling VOC emissions by vegetation is mandatory in order to improve emission estimates derived from tropospheric chemistry models. Although the Mediterranean shrublands are particularly abundant and rich in emitting species, their emission potential is poorly known. Focusing on a VOC-emitting shrub species widespread in the Mediterranean area (Cistus monspeliensis L.), we measured and analysed its emissions of terpenes taking into account the age of individuals, the season of sampling and the soil type. Sampling was done under natural environmental conditions. Species of the genus Cistus are frequently reported to be storing species, although we found only one stored monoterpene and three sesquiterpenes in very low amount. Major emitted compounds were a-pinene and b-myrcene. Total terpene emissions were not influenced by plant age but emission of some individual terpenes was positively correlated with age. A strong seasonal effect was evidenced. A larger amount of terpenes was emitted during spring and summer than during fall and winter. Summer emission rates were nearly 70 times higher than winter emission rates. Total and individual terpene emissions were influenced by soil type; emissions on siliceous substrate were ca. seven times higher than those on calcareous substrate. In conclusion, it appears clearly that environmental factors such as soil nature and season should be taken into account in order to achieve improved modelling of terpene emissions by shrub species

Potential impact of climate change on length of ignition danger season in Mediterranean shrubland of North Sardinia

The main aim of this work is to identify useful tools to forecast impacts of expected climate change on live fuel moisture content (Live FMC) in Mediterranean shrublands

Effects of a large irrigation reservoir on aquatic and riparian plants: a history of survival and loss

Dammed rivers have unnatural stream flows, disrupted sediment dynamics, and rearranged geomorphologic settings. Consequently, fluvial biota experiences disturbed functioning in the novel ecosystems. The case study is the large irrigation reservoir Alqueva in Guadiana River, Southern Iberia. The study area was divided into three zones: upstream and downstream of the dam and reservoir. For each zone, species composition and land use and land cover (LULC) were compared before and after the Alqueva Dam implementation. Data consist of aquatic and riparian flora composition obtained from 46 surveys and the area (%) of 12 classes of LULC obtained in 90 riverine sampling units through the analysis of historical and contemporary imagery. There was an overall decrease of several endemic species and on the riparian shrublands and aquatic stands, although di erences in the proportion of functional groups were not significant. Nevertheless, compositional diversity shows a significant decline in the upstream zone while landscape diversity shows an accentuated reduction in the reservoir area and downstream of the dam, which is likely related to the loss of the rocky habitats of the ‘old’ Guadiana River and the homogenization of the riverscape due to the irrigation intensification. The mitigation of these critical changes should be site-specific and should rely on the knowledge of the interactions between surrounding lands, ecological, biogeomorphologic, and hydrological components of the fluvial ecosystemsinfo:eu-repo/semantics/publishedVersio

Functional diversity as indicator of ecosystem functioning in Mediterranean riparian forests

Doutoramento em Engenharia Florestal e dos Recursos Naturais / Instituto Superior de Agronomia. Universidade de LisboaRiparian forests are ecosystems of high biodiversity and complexity driven by diverse environmental factors and increasingly threaten by anthropogenic pressures. Understanding and predicting vegetation responses to these factors have become one of the most challenging tasks in riparian ecology. This thesis aims to analyze the functional diversity responses of the Mediterranean riparian forests affected by multiple stressors to give insights into ecosystem functioning. The specific objectives were: (i) to assess the worldwide application of functional trait-based approaches in riparian forests; (ii) to determine the key habitat and regional environmental factors that influence the functional diversity of different forests; (iii) to assess the functional diversity patterns of aquatic plants and riparian woody vegetation to streamflow regulation. The results showed that the functional diversity concept has a long history of evolution. Its application to riparian forests has been increasing in the last two decades, with guild approaches becoming more popular than functional diversity indices. Functional richness is the most applied index in riparian plant studies. Amongst the environmental key-factors, precipitation plays a determinant role on the functional diversity of Mediterranean riparian forests, though especially pronounced for Mediterranean shrublands due to their low functional redundancy. Streamflow regulation can foster diverse stress-related functional strategies in contrasting biomes (boreal and Mediterranean), resulting in diverse functional diversity patterns. This result is likely related to a long legacy of adaptations to natural hydrological stress and to the magnitude of streamflow regulation. Further, diverse types of streamflow regulation (run-of-river dams and storage reservoirs) impair differently the cover and functional diversity of bryophytes, vascular macrophytes and riparian woody vegetation. The observed patterns of functional diversity can inform on the conservation status of the Mediterranean riparian forests and allow anticipating the vulnerability of the riparian ecosystems to future changes, which can guide mitigation, conservation or restoration plansN/

Multiscale assessment of woody species recruitment in Mediterranean shrublands: facilitation and beyond

Forest recovery in Mediterranean environments is influenced by factors such as aridity, herbivory and facilitation by shrubs, as well as by seed limitation in the case of highly fragmented forests. How these various factors interact can determine the direction of secondary succession, yet these interactions are poorly understood. We assessed the relative importance of several factors in forest species recruitment in Retama sphaerocarpa (L.) Boiss (Retama) shrublands at different spatial scales.Ministerio de Economía y CompetitividadComunidad de Madri

Effects of warmer and drier climate conditions on plant composition and biomass production in a Mediterranean shrubland community

The last IPCC report predicts warmer and drier conditions for the future European climate and the Mediterranean basin could be highly sensible to future climatic change. In order to investigate how the forecast more stressing factors could affect Mediterranean shrubland ecosystems, an appropriate manipulation of the microclimate was carried out in an area covered by Mediterranean maquis aimed at extending the drought period and increasing the night-time temperature. Soil cover, plant growth, litterfall, leaf water status, and leaf nutritional status were monitored over three growing seasons. The manipulation altered the microclimate according to common scenarios, increasing mean annual night-time air temperature by about 1 °C and mean annual temperature by about 0.5 °C, and decreasing precipitation between 6-46% of the total rainfall during the growing seasons. A general increase of vegetation cover was observed in the whole community during the three years of experimentation. This positive temporal pattern was mainly observed in control and warming treatment, whereas in the drought treatment it was less evident. At species-specific level, a clear negative effect of drought treatment was observed for C. monspeliensis percentage cover. Shoot elongation was not significantly affected by the warming treatment. A significant negative effect of drought treatment was noticed in the 2001-2002 and 2002-2003 growing seasons. An increase of N and P concentrations in the drought treatment in Cistus was observed and it can be explained by the reduced shoot growth induced by the water shortage that we had observed in the same treatment. The absence of a concentration effect on the other two species could be the signal of the different behaviour with regard to a drier climate, and therefore could be a symptom of future change in species composition. We underline the need of longterm observation, because of the different responses of plants in the short and long- term conditions

An Ecological Model for Predicting Behaviour of Mediterranean Shrublands

In order to build dynamic models for prediction and management of degraded Mediterranean forest areas was necessary to build MARIOLA model, which is a calculation computer program. This model includes the following subprograms. 1) bioshrub program, which calculates total, green and woody shrubs biomass and it establishes the time differences to calculate the growth. 2) selego program, which builds the flow equations from the experimental data. It is based on advanced procedures of statistical multiple regression. 3) VEGETATION program, which solves the state equations with Euler or Runge-Kutta integration methods. Each one of these subprograms can act as independent or as linked programs

Harmonized dataset of surface fuels under Alpine, temperate and Mediterranean conditions in Italy. A synthesis supporting fire management

Surface biomass characterization plays a key role in wildfire management. It allows classifying vegetation fuels flammability for fire risk analysis, to define silvicultural prescriptions for fire hazard reduction, to plan prescribed burning, or to model fire behavior and its effects, such as greenhouse gas and pollutant emissions. To facilitate fuel classification and analysis of potential fire behavior and effects in Italy, we harmonized 634 measurements of surface wildland fuels from Alpine, temperate and Mediterranean environments. The dataset provides quantitative data for duff, fine dead fuels and downed woody material, live grasses and shrubs fuel components. Surface fuel data were harmonized by subdividing loads (Mg ha(-1)) to standard size classes for dead (0-6, 6-25 and 25-75 mm) and live (0-6, 6-25 mm) fuels, collecting percent cover and depth/height (cm) of the various fuel components, and classifying observations into 19 fuelbed categories. To ensure comparability with existing vegetation classification systems, we classified each observation according to the European Fuel Map, the Corine Land Cover classes (level IV), the European Forest Types, and the forest categories of the Italian National Forest Inventory. The dataset and a photo description of each fuelbed category are available as Supplementary material. This dataset is the first step to develop several products at the national scale such as: (i) fuel type classification and mapping; (ii) carbon stock and wildfire emission estimates; (iii) calibration of fuel models for the simulation of fire behavior and effects

Effect of thermal shock and ruminal incubation on seed germination in Helianthemum apenninum L. Mill (Cistaceae)

Effect of thermal shock and ruminal incubation on seed germination in Helianthemum apenninum (L.) Mill. (Cistaceae). Here, we analyse the effect of different treatments on seed germination in Helianthemum apenninum (L.) Mill. (Cistaceae), considering scarification with sandpaper, thermal shock simulating the heat from fire, and incubation in the rumen of sheep and goat simulating passage through the gut of ruminants. Mechanical scarification boosted the germination (95% vs. 6% of control treatment), indicating that the seeds have a potentially high germination rate if the coat is eroded. Thermal shock did not improve germination. Incubation in rumen increased seed germination, up to a 32% after 48h in ruminal liquid versus 12% for control seeds in the case of sheep. The results suggest that germination in H. apenninum, while not enhanced by heat from fires, may be enhanced by herbivore ingestion

Una Nuova area sperimentale di lungo termine, per lo studio degli effetti dell'incremento della temperatura e del periodo di aridità in formazioni di sclerofille mediterranee

A new long-term experimental area for studying the effects of climate warming and seasonal drought on a Mediterranean shrubland community. Global changes, such as land use changes, altered atmosphere composition, and climate changes, have been altering the functioning of ecosystems with possible impacts on the degree of biodiversity. Temperature and water availability are the two main determinants of the functional processes of terrestrial ecosystems. Climatic changes could have strong effects on vulnerable ecosystems as Mediterranean shrublands/garrigue/maquis, where the growth and survival of the plants are strictly dependent on the drought and to the high summer temperature. Furthermore, other pressures, such as grazing and wildfires, occur frequently in the Mediterranean area. In order to assess the impacts of the temperature increase and precipitation reduction on Mediterranean shrublands, a new experimental area was established in Sardinia at the Porto Conte forest, Alghero (SS). A system of automatic roofs covers 6 experimental plots (20 m2), in order to simulate an increase of temperature during the night (3 plots) or to intercept the precipitations during a 2-3 months period (3 plots). Three additional plots are used as control. All the observations were conducted in other five European shrubland ecosystems, according to common protocols developed in the context of the European project VULCAN (www.vulcanproject.com). The studies of the different ecological and physiological processes are organised in working packages (Plant, Soil, Fauna, Water) and integrated in a risk assessments evaluation. The aim of this paper is to analyse the first two years of data, to demonstrate the microclimatic modifications induced by the experimental system