Phytotoxic effects of sewage sludge extracts on the germination of three plant species.

In order to evaluate the ability of three types of extracts to explain the ecotoxicological risk of treated municipal sewage sludges, the OECD 208A germination test was applied using three plants (Lolium perenne L., Brassica rapa L., and Trifolium pratense L.

High invasive pollen transfer, yet low deposition on native stigmas in a Carpobrotus-invaded community.

Background And Aims: Invasive plants are potential agents of disruption in plant-pollinator interactions. They may affect pollinator visitation rates to native plants and modify the plant-pollinator interaction network. However, there is little information about the extent to which invasive pollen is incorporated into the pollination network and about the rates of invasive pollen deposition on the stigmas of native plants.

Genetic structure and diversity in Ramonda myconi (Gesneriaceae): effects of historical climate change on a preglacial relict species.

The importance of the Mediterranean Basin as a long-term reservoir of biological diversity has been widely recognized, although much less effort has been devoted to understanding processes that allow species to persist in this area. Ramonda myconi (Gesneriaceae) is a Tertiary relict plant species restricted to the NE Iberian Peninsula. We used RAPD and chloroplast markers to assess the patterns of genetic structure in eight mountain regions covering almost the full species range, to identify the main historical processes that have shaped its current distribution and to infer the number and location of putative glacial refugia.

Toxic effects of digested, composted and thermally-dried sewage sludge on three plants.

In order to evaluate potential toxic effects of stabilized sewage sludge that are currently applied to agricultural soils, three types of municipal sewage sludge and one pig slurry were subjected to phytotoxicity assays using three plants (Brassica rapa, Lolium perenne and Trifolium pratense). Equivalent batches of aerobically and anaerobically-digested sludge (F) from two municipal wastewater treatment plants, were composted (C) or thermally dried (T). In addition, one anaerobically-digested and thermally-dried pig slurry (P) was tested.

Contrasting effects of invasive plants in plant-pollinator networks.

The structural organization of mutualism networks, typified by interspecific positive interactions, is important to maintain community diversity. However, there is little information available about the effect of introduced species on the structure of such networks. We compared uninvaded and invaded ecological communities, to examine how two species of invasive plants with large and showy flowers (Carpobrotus affine acinaciformis and Opuntia stricta) affect the structure of Mediterranean plant-pollinator networks.

Woody plant richness and NDVI response to drought events in Catalonian (northeastern Spain) forests.

The role of species diversity on ecosystem resistance in the face of strong environmental fluctuations has been addressed from both theoretical and experimental viewpoints to reveal a variety of positive and negative relationships. Here we explore empirically the relationship between the richness of forest woody species and canopy resistance to extreme drought episodes. We compare richness data from an extensive forest inventory to a temporal series of satellite imagery that estimated drought impact on forest canopy as NDVI (normalized difference vegetation index) anomalies of the dry summer in 2003 in relation to records of previous years.

Feeding inhibition in the soil collembolan Folsomia candida as an endpoint for the estimation of organic waste ecotoxicity.

Despite the increasing quantities of organic wastes that are being reused in soils, there are few studies that focus on the selection of bioassays for the ecotoxicological risk assessment of organic wastes to soils. In the present study, differences in feeding inhibition in the soil collembolan Folsomia candida were evaluated as an ecotoxicological endpoint for the assessment of risk to soils amended with polluted organic wastes. Seven organic wastes (dewatered sewage sludges, thermally dried sewage sludges, composted sewage sludges, and a thermally dried pig slurry) were tested.

Comparison of solid-phase and eluate assays to gauge the ecotoxicological risk of organic wastes on soil organisms.

Development of methodologies to assess the safety of reusing polluted organic wastes in soil is a priority in Europe. In this study, and coupled with chemical analysis, seven organic wastes were subjected to different aquatic and soil bioassays. Tests were carried out with solid-phase waste and three different waste eluates (water, methanol, and dichloromethane).

The relevance of xylem network structure for plant hydraulic efficiency and safety.

The xylem is one of the two long distance transport tissues in plants, providing a low resistance pathway for water movement from roots to leaves. Its properties determine how much water can be transported and transpired and, at the same time, the plant's vulnerability to transport dysfunctions (the formation and propagation of emboli) associated to important stress factors, such as droughts and frost. Both maximum transport efficiency and safety against embolism have classically been attributed to the properties of individual conduits or of the pit membrane connecting them.

Leaf and shoot water content and leaf dry matter content of Mediterranean woody species with different post-fire regenerative strategies.

Background And Aims: Post-fire regeneration is a key process in Mediterranean shrubland dynamics, strongly determining the functional properties of the community. In this study, a test is carried out to determine whether there is co-variation between species regenerative types and functional attributes related to water use.

Methods: An analysis was made of the seasonal variations in leaf relative water content (RWC), leaf dry matter content (LDMC), leaf moisture (LM) and live fine fuel moisture (LFFM) in 30 woody species of a coastal shrubland, with different post-fire regenerative strategies (seeding, resprouting or both).

Plant VOC emissions: making use of the unavoidable.

All plants emit substantial amounts of phytogenic volatile organic compounds (PVOCs), which include alkanes, alkenes, alcohols, aldehydes, eters, esters and carboxylic acids. Defence, communication and/or protection against extreme conditions have been proposed as reasons for these emissions. However, Rosenstiel and colleagues have recently proposed that emission of PVOCs represents a metabolic 'safety valve' by preventing the unnecessary sequestration of phosphates.

Introduction of the factor of partitioning in the lithogenic enrichment factors of trace element bioaccumulation in plant tissues.

Bioindicators are widely used in the study of trace elements inputs into the environment and great efforts have been conducted to separate atmospheric from soil borne inputs on biomass accumulation. Many monitoring studies of trace element pollution take into account the dust particles located in the plant surface plus the contents of the plant tissues. However, it is usually only the trace element content in the plant tissues that is relevant on plant health.

Demography of the invasive geophyte Oxalis pes-caprae across a Mediterranean island.

Background And Aims: Success during the early stages of the life-history of alien plants is essential for invasion to occur. The reproductive components of plant invaders have mostly been studied in species reproducing sexually but little is known about invaders that depend exclusively on vegetative reproduction. In this paper, the importance of the different recruitment stages on population growth is quantified and, thus, the invasion potential of the South African annual geophyte Oxalis pes-caprae invading Mediterranean ecosystems is assessed.

A multi-criteria evaluation of organic amendments used to transform an unproductive shrubland into a Mediterranean dehesa.

Environmental and health problems associated with the use of digested sewage sludge hinder its application and encourage the introduction of additional treatments such as composting and thermal drying. The aim of this paper is to assess the possibility of using three different types of sewage sludge (digested, composted and thermally dried) to improve soil fertility and enhance the transformation of an unproductive shrub land into a Mediterranean dehesa for grazing purposes and also to reduce wildfire risk. In total, 10t ha(-1) of dry matter of three types of sewage sludge were spread on the soil surface of 4x5m field plots, and then seeded with a mixture of grasses.

Dynamics of the enhanced emissions of monoterpenes and methyl salicylate, and decreased uptake of formaldehyde, by Quercus ilex leaves after application of jasmonic acid.

Jasmonic acid (JA) is a signalling compound with a key role in both stress and development in plants, and is reported to elicit the emission of volatile organic compounds (VOCs). Here we studied the dynamics of such emissions and the linkage with photosynthetic rates and stomatal conductance. We sprayed JA on leaves of the Mediterranean tree species Quercus ilex and measured the photosynthetic rates, stomatal conductances, and emissions and uptake of VOCs using proton transfer reaction mass spectrometry and gas chromatography after a dark-light transition.

Ecotoxicological and fertilizing effects of dewatered, composted and dry sewage sludge on soil mesofauna: a TME experiment.

The effects of dewatered, composted and dry urban sewage sludge on the soil mesofauna were tested in mesocosms. PVC containers were filled with soil/sludge mixtures in a proportion to amount to 6% organic matter content and were colonized with soil fauna coming from undisturbed forest soils. Mesocosms were incubated under laboratory conditions for 7, 30, 60, 120 and 180 days, after which fauna was extracted in Berlese funnels.

Trace element accumulation in the moss Hypnum cupressiforme Hedw. and the trees Quercus ilex L. and Pinus halepensis Mill. in Catalonia.

We studied trace element accumulation in the moss Hypnum cupressiforme and the widely distributed Mediterranean trees Quercus ilex and Pinus halepensis located at increasing distances from the Barcelona Metropolitan Area. Hypnum cupressiforme, Quercus ilex and, to a somewhat lesser extent, Pinus halepensis, have proved to be adequate as possible accumulative monitoring species in relation to trace elements pollution. No significant effects of crown orientation were found.

Isoprenoids: an evolutionary pool for photoprotection.

Plants have evolved several mechanisms for getting rid of excess energy in photosynthetic membranes, some of which involve isoprenoid compounds. In all photosynthetic organisms, the carotenoids beta-carotene and zeaxanthin, and tocopherols serve an important photoprotective role, either by dissipating excess excitation energy as heat or by scavenging reactive oxygen species (ROS) and suppressing lipid peroxidation. Isoprene and some monoterpenes, diterpenes and other carotenoids also occur in some plant lineages.

Ozone exposure induces the activation of leaf senescence-related processes and morphological and growth changes in seedlings of Mediterranean tree species.

Four Mediterranean tree taxa, Quercus ilex subsp. ilex, Quercus ilex subsp. ballota, Olea europaea cv.

Using plant biomonitors and flux modelling to develop O3 dose-response relationships in Catalonia.

We used tobacco Bel-W3 biomonitoring data and ozone flux modelling (WINDEP model) with the aim of developing the absorbed dose-response relationship, and comparing this approach with the most commonly used AOT40 (the sum of hourly ozone concentrations above a cut-off of 40 ppb during daylight hours, when global radiation exceeds 50 W m(-2)) in the estimation of exposure-damage curves. Leaf damage values were more related to OAD(15 days, potential) (potential ozone absorbed dose calculated over 15 consecutive days) than to AOT40 in all the studied stations. An OAD(15 days, potential) of 180 mg m(-2) was found to be the threshold for damage to the most sensitive species in this region under well watered conditions.

Contrasting growth changes in two dominant species of a Mediterranean shrubland submitted to experimental drought and warming.

Background And Aims: Climate projections predict drier and warmer conditions in the Mediterranean basin in the next decades. The possibility of such climatic changes modifying the growth of two Mediterranean species, Erica multiflora and Globularia alypum, which are common components of Mediterranean shrublands, was assessed.

Methods: A field experiment was performed from March 1999 to March 2002 to prolong the drought period and to increase the night-time temperature in a Mediterranean shrubland, where E.

Complex spatiotemporal phenological shifts as a response to rainfall changes.

•  Climatic warming produces significant gradual alterations in the timing of life-cycle events, and here we study the phenological effects of rainfall-pattern changes. •  We conducted ecosystem field experiments that partially excluded rain and runoff during the growing season in a Mediterranean forest and in a mediterranean shrubland. Studies of time-series of leaf-unfolding, flowering and fruiting over the last 50 yr in central Catalonia were carried out, and greenup onset in the Iberian Peninsula was monitored by satellite images.

Partitioning of water and nitrogen in co-occurring Mediterranean woody shrub species of different evolutionary history.

We studied the interspecific and intraspecific variation in the development of water stress and in the use of different water and nitrogen sources during the spring (wet season) and summer (dry season) in a shrub community in NE Spain. We measured shoot water potentials, stable deuterium isotopic composition (delta D) of xylem sap, leaf mass per area, leaf N and C concentrations, gas exchange, leaf delta(13)C, and leaf delta(15)N of the dominant species (Quercus coccifera, Arbutus unedo, Pistacia lentiscus, Erica multiflora, Globularia alypum). The delta D, the delta(13)C and the shoot water potential values showed diurnal, seasonal, intraspecific and interspecific variation in the source and use of water.

BVOCs: plant defense against climate warming?

Plants emit a substantial amount of biogenic volatile organic compounds (BVOCs) into the atmosphere. These BVOCs represent a large carbon loss and can be up to approximately 10% of that fixed by photosynthesis under stressful conditions and up to 100gCm(-2) per year in some tropical ecosystems. Among a variety of proven and unproven BVOC functions in plants and roles in atmospheric processes, recent data intriguingly link emission of these compounds to climate.

Nitrogen deposition in Mediterranean forests.

Atmospheric deposition of inorganic nitrogen was studied at two forested sites in the Montseny mountains (northeast Spain), peripheral to the Barcelona conurbation, and at a nearby lowland town, using bulk deposition, wet-only deposition, throughfall, and dry deposition inferred from branch-washes and surrogate surfaces (metacrylate plates). Bulk deposition inputs of ammonium and nitrate did not show significant temporal trends over a 16-year period. Bulk inputs of inorganic N were moderate, ranging from 6 to 10 kg N ha(-1) year(-1) depending on the time period considered and the degree of site exposure to polluted air masses from the Barcelona conurbation.