Soil pollution is one of the main threats to soil ecosystem health, and the combination of microbial remediation with phytoremediation can promote contaminant degradation and contribute to the revitalization of ecosystem functions. Plant interactions with the surrounding physical and biological environments determine the formation of new ecosystems, which, similarly to natural ones, can provide several ecosystem services. Despite the increasing diffusion of phytoremediation and the large areas potentially suitable for the application of these technologies, the delivery of ecosystem services during phytoremediation interventions has rarely been investigated. In the framework of a bio-phytoremediation project, the present work explored the capacity of a new plant cover created at a site under bio-phytoremediation (area: 0.52 ha) to provide supporting, regulating, and cultural Ecosystem Services. The daily cumulative cooling effect due to plant transpiration during summer was 12.7 °C m−2 day−1, with species characterized by the highest Leaf Area Index and leaf transpiration rates (such as Chrysopogon zizanioides, evergreen shrub species, and Populus nigra) contributing the most to air cooling. Thanks to plant photosynthesis, 177 kg of C was sequestered each year, while the air pollution intercepted by the plant leaves amounted to 1.82 kg per year. After 30 months of phytoremediation, an increase in soil microbial activity indicated a progressive improvement in soil quality. Similarly, the cytometric analysis of hepatopancreatic cells from isopods indicated that the bioindicator organism actively and positively responded to the recovering environment, thus supporting the effectiveness of the ongoing remediation of soil quality. Finally, the implementation of the bio-phytoremediation intervention led to the creation of new habitats, increased ecological connectivity in the surrounding urban area, and generated an aesthetic value comparable to that of urban greenery. These analyses provided evidence that these techniques not only supported soil remediation and site securing but also contributed to improving citizen well-being in the proximity of the site and the environmental quality of the area. These significant positive externalities of phytoremediation should be considered when selecting technologies for environmental clean-up.

Bioaugmentation, defined as the strategic incorporation of specifically selected microbial biomass into contaminated environments, can significantly enhance the biodegradation of pollutants and is extensively employed in soil bioremediation efforts. A multistep screening process was applied to develop an autochthonous microbial consortium, including (i) hydrocarbonoclastic strain isolation from soil chronically contaminated with petroleum hydrocarbons, (ii) bacterial selection according to genomic and functional traits, and (iii) consortium validation in the native contaminated soil through microcosm experiments. The selection of strains with the ability to degrade alkanes and aromatic hydrocarbons on synthetic media was further supported by genomic analysis, delivering a consortium with complementary degradative properties. The outcomes of the microcosm experiments corroborated the efficacy of the selected indigenous consortium, demonstrating that the combination of Acinetobacter guillouiae, A. radioresistens, and Pseudomonas zarinae as an inoculum in the bioaugmentation strategy was successful in achieving the removal of up to 26% and 76% of linear and polycyclic aromatic hydrocarbons, respectively, thereby effectively addressing areas where natural attenuation was insufficient.

Since its first detection in 2013, Xylella fastidiosa subsp. pauca (Xfp) has caused a devastating Olive Quick Decline Syndrome (OQDS) outbreak in Southern Italy. Effective disease surveillance and treatment strategies are urgently needed to mitigate its impact. This study investigates the short-term (1.5 years) effects of thymol-based treatments on infected olive trees of the susceptible cultivar Cellina di Nardò in two orchards in Salento, Apulia region. Twenty trees per trial received a 3% thymol solution either alone or encapsulated in a cellulose nanoparticle carrier. Over two years, sap flux density and canopy-transmitted solar radiation were monitored using TreeTalker sensors, and spectral greenness indices were calculated. Xfp cell concentrations in plant tissues were quantified via qPCR. Neither thymol treatment halted disease progression nor significantly reduced bacterial load, though the Xfp cell concentration reduction increased over time in the preventive trial. Symptomatic trees exhibited increased sap flux density, though the treatment mitigated this effect in the curative trial. Greenness indices remained lower in infected trees, but the response to symptom severity was delayed. These findings underscore the need for longer-term studies, investigation of synergistic effects with other phytocompounds, and integration of real-time sensor data into adaptive disease management protocols.

This review aims to address the specific challenges of forest decline in Mediterranean Fagaceae ecosystems driven by the alien invasive Phytophthora cinnamomi and global changes. In a scenario of climate change and anthropic pressure, this review seeks to offer a comprehensive overview of the current state of P.cinnamomi invasion, focusing on its biology, ecology and epidemiology in different Mediterranean forest ecosystems, and providing an update on diagnosis, impact and current management measures. Recent studies have significantly advanced our understanding of the decline of Mediterranean Fagaceae forests driven by Phytophthora spp. The introduction of the plant holobiont concept and microbial invasion biology and ecology has reshaped the study of plant–microbe interactions. This perspective, which considers the tree as an ecosystem composed of the tree itself together with its associated microbiome has been pivotal in developing holistic management strategies to mitigate pathogen impacts. The network of interactions between components of the microbial community of healthy and diseased trees, has been the object of several recent studies that highlighted the complex dynamics of host–pathogen interaction and offered the option for biotechnological applications including the use of helper microorganisms and antagonists. The collaboration among research institutions from Italy, Spain and Portugal has resulted in a detailed review that emphasizes the importance of tailored management protocols for different ecosystems. Engaging stakeholders and citizens in integrated pest management (IPM) strategies has proven crucial for effective forest management. The findings underscore the need for continuous monitoring, innovative treatment methods, and public awareness to mitigate the impacts of Alien Invasive Forest Phytophthoras (AIFPs) and ensure the sustainability of Mediterranean Fagaceae forests.

Dredging activities produce large amounts of polluted sediments that require adequate management strategies. Sediment reuse and relocation can involve several environmental issues, such as the release of CO2 and nitrogen compounds in the environment, the transfer of metals to plant tissues and the persistence of phytotoxic compounds. In this framework, the aim of the present work is to evaluate the use of biochar at different doses, in combination with plant growth, to reduce the environmental impacts polluted dredged sediments. Irrespective to the plant treatment, the amendment of the sediment with the lowest dose of biochar (3%) reduced by 25% the CO2 emissions of the substrate, by 89% the substrate carbon loss and by 35% the amount of nitrogen released into the environment (average values of the three plant treatments). The negative priming effect of biochar on organic matter mineralization can be responsible for the beneficial reduction of carbon and nitrogen release in the environment. The lack of similar effects observed at the higher biochar doses can depend on the low albedo of the biochar particles, causing the substrate warming (+1 °C for highest biochar dose) and accelerating the organic matter mineralization. Finally, shrub growth in combination with 3% biochar was able to offset the CO2 emission of the sediment and to reduce the amount of nitrogen lost. This work provides new insight on the potential benefit related to the biochar amendment of organic matter-rich dredged sediments, suggesting that the use of moderate dose of wood biochar in combination with shrub plantation can reduce the release of CO2 and nitrogen compounds in the environment.

The capacity to forecast the effects of climate change on biodiversity largely relies on identifying traits capturing mechanistic relationships with the environment through standardized field experiments distributed across relevant spatial scales. The effects of short-term experimental manipulations on local communities may overlap with regional climate gradients that have been operating during longer time periods. However, to the best of our knowledge, there are no studies simultaneously assessing such long-term macroecological drivers with local climate manipulations. We analysed this issue with springtails (Class Collembola), one of the dominant soil fauna groups, in a standardized climate manipulation experiment conducted across six European countries encompassing broad climate gradients. We combined community data (near 20K specimens classified into 102 species) with 22 eco-morphological traits and reconstructed their phylogenetic relationships to track the evolution of adaptations to live at different soil depths, which is key to cope with desiccation. We then applied joint species distribution models to investigate the combined effect of the regional aridity gradient with the local experimental treatment (drought and warming) over the assembly of springtail communities and tested for significant trait-environment relationships mediating their community-level responses. Our results show (1) a convergent evolution in all three major collembolan lineages of species adapted to inhabit at different soil strata; (2) a clear signature of aridity selecting traits of more epigeic species at a biogeographical scale and (3) the association of short-term experimental drought with traits related to more euedaphic life-forms. The hemiedaphic condition would be the plesiomorphic state for Collembola while the adaptations for an epigeic life would have been secondarily gained. Epigeic springtails are not only more resistant to drought, but also have a higher dispersal capacity that allows them to seek more favourable micro-habitats after experiencing drier conditions. The observed relative edaphization of the springtail communities after short-term experimental drought may thus be a transient community response. The disparity between macroecological trends and fast community-level responses after climate manipulations highlights the need of simultaneously assessing long-term and short-term drivers at broad spatial scales to adequately interpret trait-environment relationships and better forecast biodiversity responses to climate change. Read the free Plain Language Summary for this article on the Journal blog.

data used in the paper "Enhancement of ecosystem carbon uptake in a dry shrubland under moderate warming: The role of 1 nitrogen-driven changes in plant morphology"

Soil salinization is typical for urban environment where de-icing agents are released in considerable amounts. Urban lawns with turf grasses are the primary components of the urban green infrastructure and are exposed to different rates of soil salinity, depending on the distance to the paved surfaces where de-icing agents are released. Plant metabolic adjustments supported by nutrients availability in soil are the key parameters necessary to cope with soil salinity. In this study we evaluated the mechanisms activated at a plant level in response to low and moderate soil salinity in a popular turf-grass mixture used for urban lawn greening. Carbohydrates and starch content as well as content of chloride were measured in plant biomass after 2.5 months of continuous irrigation with salt solution. Nutrients availability and plant-soil interactions were assessed by analyzing extracellular soil enzymatic activity in the rhizosphere and N content of plant tissues. Plants increased the amount of compounds involved in the osmotic regulation in expense of storage compounds and isolated the toxic ions to old tissues. Increased plant demand for N at soil salinity was accompanied by an increase in the activity of chitinase in the rhizospheric soil, suggesting no potential restrictions for future accumulation of osmotic N-containing compounds in vegetation.

Release of heavy metals, salts and other toxic agents in the environment is of increasing concern in urban areas. Contaminants not solely decline the quality of the local environment and affect the health of human population and urban ecosystems but are also spread through runoff and leaching into non-contaminated areas. Urban lawns are the most distributed green infrastructure in the cities. Management of lawn system may either exacerbate the negative effects of contaminants on lawn functioning either help to withstand the toxic effects and maintain the lawn ecosystem health and the efficient release of ecosystem services. The aim of this study was to evaluate the interactions between the lawn management, the lawn functioning, and the release into the soil of typical urban contaminants. For this purpose, Festuca arundinacea grass was planted in a turf-sand mixture with and without amendment addition (zeolite + vermicompost). To reproduce the impact of traffic-related contaminants in proximity of the road, pots were treated with a solution containing de-icing salt (NaCl) and 6 heavy metals (Zn, Cd, Pb, Cr, Cu, Ni), imitating road runoff solution. After contamination, half of pots was maintained at optimum soil water content (Smart irrigation), another half was left to periodical drying in order to simulate conditions with discontinuous watering (Periodical irrigation). The same experimental scheme was reproduced for unplanted soil. CO2 net ecosystem exchange (NEE), soil and ecosystem respiration as well as flux from unplanted soil (heterotrophic respiration) were measured shortly after the treatment (short-term) and up 3 months since the treatment start (long-term). Soil amendment stimulated plant productivity and increased the efficiency of the system in C uptake (+56% NEE). A relevant reduction of NEE was observed from 14 to 40 days after the application of traffic-related contaminants in both amended and non amended pots. During this period the contaminants had the greatest impact on lawn NEE subjected to Periodic irrigation (-49% and -66% in amended and non amended pots, respectively), while lawn under Smart irrigation was less affected (-35% and -26% in amended and non amended pots, respectively). Different respiration sources (ecosystem respiration, soil respiration, heterotrophic respiration) were characterized by different sensitivity to management and contamination. Heterotrophic flux was not sensitive to soil amending but declined with contamination with enhanced negative effect under Smart irrigation. Response of ecosystem respiration to contamination was less pronounced in confront to soil respiration suggesting leaf-level buffering. Three months later, the effect of contaminants on lawn gas exchange ceased for all treated pots. Instead, the irrigation effect persisted depending on whether pots were amended or not. In non amended pots NEE was reduced by 18% under Periodic irrigation, while this effect was not present in amended pots. We conclude, that performance of such green infrastructure as lawns in terms of C sequestration under multiple anthropogenic stressors could be efficiently improved through soil amending and irrigation control. Current research was financially supported by RFBR No. 19-29-05187 and RSF No. 19-77-30012.

Net ecosystem CO2 exchange is the result of net carbon uptake by plant photosynthesis and carbon loss by soil and plant respiration. Temperature increases due to climate change can modify the equilibrium between these fluxes and trigger ecosystem-climate feedbacks that can accelerate climate warming. As these dynamics have not been well studied in dry shrublands, we subjected a Mediterranean shrubland to a 10-year night-time temperature manipulation experiment that analyzed ecosystem carbon fluxes associated with dominant shrub species, together with several plant parameters related to leaf photosynthesis, leaf morphology, and canopy structure. Under moderate night-time warming (+0.9 degrees C minimum daily temperature, no significant reduction in soil moisture), Cistus monspeliensis formed shoots with more leaves that were relatively larger and denser canopies that supported higher plant-level photosynthesis rates. Given that ecosystem respiration was not affected, this change in canopy morphology led to a significant enhancement in net ecosystem exchange (+47% at midday). The observed changes in shoot and canopy morphology were attributed to the improved nutritional state of the warmed plants, primarily due to changes in nitrogen cycling and higher nitrogen resorption efficiency in senescent leaves. Our results show that modifications in plant morphology triggered by moderate warming affected ecosystem CO2 fluxes, providing the first evidence for enhanced daytime carbon uptake in a dry shrubland ecosystem under experimental warming.

Release of de-icing agents is the main cause of increasing soil salinization in urban and rural areas. Grasses are the dominant vegetation in urban lawns and are exposed to different rates of soil salinization depending on the distance to the paved salt-affected surfaces. The capacity of these ecosystems to maintain C sequestration and nutrient cycling functioning depends on the sensitivity to salinization of the main players: primary producers and their interaction with microbial community. In this mesocosm study we aimed to evaluating the impact of soil secondary salinization rates on the functioning of Lolium perenne. Salinization treatments were applied for two months in spring, irrigating the mesocosms with the commonly used de-icing agent NaCl at two concentration, 30 mM (low salinity treatment) and 90 mM (moderate salinity treatment). The leaf physiological responses of Lolium were assessed monitoring photosynthetic rates (A), stomatal conductance (gs) mesophyll conductance (gm), carboxylation capacity (Vcmax). Quantitative limitation analysis (QLA) was applied to calculate the relative contribution of diffusive and biochemical limitation to photosynthesis under salinization. Productivity was estimated by regular mowing of plants to 4cm height. Finally, plants were harvested and analyzed on leaf mass per area (LMA), leaf N content and 15N isotope composition. Rhizosphere soil was sampled and analyzed on the activity of enzymes involved in the cycling of C, N, S and P. Salinity increased LMA and leaf N, reducing Lolium aboveground productivity. Photosynthetic rates were almost halved under both salinity treatments. QLA shows that photosynthesis was mainly limited by gm, limitation accounting for 68% and 54% of the total limitation in 30mM and 90mM, respectively. gs reduction significantly limited photosynthesis only in 90 mM (32% of total limitation), while biochemical limitations (due to a reduction in Vcmax) remained below 20% of the total limitation in both treatments. Mesophyll conductance to CO2 depends on leaf anatomical and biochemical traits and is usually negatively related to LMA. The increased LMA observed under salinity treatments suggests that changes in the leaf structure (like increased cell wall thickness) could be responsible for most of the A (and consequently productivity) reduction. On the other hand, the increased leaf N content is in agreement with the lack of significant reduction in Vcmax. Accumulation of N compounds in leaves in response to salinization was accompanied by a decline in soil extracellular enzymes involved in N and other cycles. Over-competing of the microbial pool in access to nutrients by vegetation could be suggested in conditions of salinization. Because the belowground biomass was not affected, decline in C losses with salinization could be hypothesize which should balance the shortage in C inputs. In conclusion, salinization mainly limited A through gm limitation, probably associated to the increased LMA. At the same time, altering the capacity of the microbial pool to compete for N, it increased leaf N, possibly reducing the impact of biochemical limitation on A and avoiding a further A and productivity decline. Experiment was financially supported by the Russian Science Foundation, project No.17-77-20046.

Forests play a key role in the climate system thanks to their large carbon uptake and storage. On the other hand, forests are vulnerable to climate extremes and pest attacks, causing early tree mortality which in turn could reduce their carbon uptake capacity. Early tree mortality is often associated to a complex interaction of predisposing stress factors (poor site quality, unfavourable stand conditions), inciting factors (frost, drought, mechanical damage) and contributing factors (fungi, insect borers). In this context, the aim of the present work was to investigate the processes underlying the tree mortality observed in an evergreen mixed forest stand dominated by Quercus ilex, located in the Circeo National Park (central Italy). The forest has the typical structure of an old-coppice not more managed (actual rotation time about 2 times that the normal), and was recently (2016) affected by an outbreak of Asian ambrosia beetle (Xylosandrus compactus) and Granulate ambrosia beetle (Xylosandrus crassiusculus) that caused an extensive trees crown browning. In 2019, plots were set in the area to monitor the beetle population dynamic and their impact on tree mortality. In each plot, species, dimension (DBH), stage of dieback, stem origin (resprouts after coppicing or from seed), presence of epicormic shoots and subcortical fungi stroma, were recorded for each woody plant. The plot survey revealed a high frequency of stems classified in a declining stage or dead, on average 42% of the standing stems, with significant differences among the species: 97%, 85%, 74% and 47% for Arbutus unedo, Quercus ilex, Phyllirea latifolia and Fraxinus ornus respectively. The higher stem mortality of Q. ilex was recorded in the smaller diameter classes, suggesting that the self-thinning process played an important role on the observed mortality as typical in the old not more managed coppices. To disentangle the role of the interruption of the management from the climatic and biological drivers, time trends on NDVI index were constrained with the duration of the summer dry seasons and comparing our forest with similar Q. ilex forest coppices in the region and regularly managed. Furthermore, the contribution of recent ambrosia beetles attack was assessed identifying the presence of twigs with signs of previous beetle attack on healthy, declining and dead plants. Our findings point towards complex tree mortality dynamics, in which the competition generated by the stand abandonment predisposed the forest to the insect attack, leading to the general decline of the forest stand.

Deicing agents cause soil salinization and degradation in urban areas. We assessed the capacity of urban lawns to maintain carbon sequestration and nutrient cycling with increasing soil salinity. The sensitivity to soil salinity of the main ecosystem players: plants and microorganisms were assessed considering their complex interactions between each other and environment. The effects of low and moderate soil salinization by common deicing agent (NaCl) were evaluated in mesocosms planted with two urban lawns: Lolium perenne and mixture of grasses. Mesocosm-, plant-, and soil-level gas exchange were assessed on a short-term (days) and long-term (months) scales. Microbial response was characterized by analyzing the microbial properties and activities of nine enzymes. Carbon balance remained independent on the salinity due to cancelling effect of lowered gross primary production (GPP, -20%), decreased C input by plants into the soil (-40% for mixture) balanced by slower microbial decomposition of organic matter (-20%) and so, lower soil respiration (-35%). GPP declined as a long-term response by a combination of stomatal constraint on photosynthesis with leaf respiration increase. Toxic effects of salinization on soil respiration were observed only for temperatures above 15 degrees C. Microbial community with high C:N ratio (common for fungi) was the most sensitive to salinization. The death of microbial biomass (-31% for Lolium) and cell lysis increased soil enzyme activities (+38% for Lolium). We conclude that C balance of urban lawns remain homeostatic at secondary salinization. Temperature effects and plant-microbial interactions will determine C and nutrients cycling under salinity stress in urban lawns.

The lead was one of the main elements in the glazes used to colour ceramic tiles. Due to its presence, ceramic sludge has been a source of environmental pollution since this dangerous waste has been often spread into the soil without any measures of pollution control. These contaminated sites are often located close to industrial sites in the peri-urban areas, thus representing a considerable hazard to the human and ecosystem health. In this study, we investigated the lead transfer into the vegetation layer (Phragmites australis, Salix alba and Sambucus nigra) growing naturally along a Pb-contaminated ditch bank. The analysis showed a different lead accumulation among the species and their plant tissues. Salix trees were not affected by the Pb contamination, possibly because their roots mainly develop below the contaminated deposit. Differently, Sambucus accumulated high concentrations of lead in all plant tissues and fruits, representing a potential source of biomagnification. Phragmites accumulated large amounts of lead in the rhizomes and, considering its homogeneous distribution on the site, was used to map the contamination. Analysing the Pb concentration within plant tissues, we got at the same time information about the spread, the history of the contamination and the relative risks. Finally, we discussed the role of natural recolonizing plants for the soil pollution mitigation and their capacity on decreasing soil erosion and water run-off.

More than 1100 million ha of the lands are affected by the soil salinity globally. In Europe, soil salinization affects 1 to 4 million ha and is concentrated mainly in Mediterranean. Among the major causes of salinization in rural areas are salt-water introgression into the ground waters used for irrigation and dust suppression practices, in urban areas - deicing of roads with chloride salts (NaCl, CaCl2). To simulate urban soil salinization after the release of the deicing agents, Lolium perenne, typically used in urban public and private lawns, was planted in pots and grown in the green house for 5 months before being treated with NaCl 0 mM, 30 mM and 90 mM solution as regular irrigation practice. The grass was moved to 4 cm height. Gas exchange measurements: soil respiration, ecosystem respiration and net ecosystem exchange were measured from planted and non-planted collars, installed in the pots. Soil salinization affected negatively soil respiration rates but increased plant respiration proportionally to the level of salinization. Together with the decline in gross primary production, it resulted in no changes in the net ecosystem exchange rates between control and salt treatments. Lolium perenne could be recommended for urban lawns subjected to periodical salinization.

Leaf transpiration drives many of the processes involved in phyto-technologies, and it can represent a useful mechanism to remove water from different kind of storage basins presenting inorganic, organic or microbiological contamination (phyto-dehydration), with the aim to reduce the risk of environmental contamination. In this framework, a mesocosm-scale trial was carried out to test the capacity of different helophyte species to reduce the excess of water in an artificial pond filled with oversaturated sludge.

Hydrological cycle is expected to become the primary cause of ecosystem's degradation in near future under changing climate. Rain manipulation experiments under field conditions provide accurate picture on the responses of biotic processes to changed water availability for plants. A field experiment, mimicking expected changes in rain patterns, was established in a Mediterranean shrub community at Porto Conte, Italy, in 2001. In November 2011 Cistus monspeliensis, one of the dominating shrub species in the Mediterranean basin, was 13C labelled on plots subjected to extended rain shortage period and on control non manipulated plots. Carbon (C) allocation was traced by 13C dynamics in shoots, shoot-respired CO2, roots, microbial biomass, K2SO4-extractable C and CO2 respired from soil. Most of the recovered 13C (60%) was respired by shoots within 2weeks in control plots. In rain shortage treatment, 13C remained incorporated in aboveground plant parts. Residence time of 13C in leaves was longer under the rain shortage because less 13C was lost by shoot respiration and because 13C was re-allocated to leaves from woody tissues. The belowground C sink was weak (3-4% of recovered 13C) and independent on rain manipulation. Extended rain shortage promoted C exudation into rhizosphere soil in expense of roots. Together with lowered photosynthesis, this "save" economy of new C metabolites reduces the growing season under rain shortage resulting in decrease of shrub cover and C losses from the system on the long-term.

Understanding how different combinations of plant functional traits contribute to species fitness is a question of considerable ecological interest, that can give insights into the mechanisms controlling community assembly, and into the processes by which climate change can modify plant community structure and composition. We investigated the changes in cover degree of three shrubs (Cistus monspeliensis, Dorycnium pentaphyllum and Helichrysum microphyllum) growing in a Mediterranean garrigue subjected for 11 years to a reduced rainfall regime, following a conceptual framework based on the two‐phase resource dynamic model: considering the seasonal drought typical of the Mediterranean climate, the two‐phases were identified based on high (pulse phase) and low (interpulse phase) soil water availability. We developed a parameter proportional to the whole plant photosynthesis (plant photosynthetic index, PPI), scaling up the leaf photosynthesis to canopy level, taking into account the different canopy densities and the fluctuations in leaf biomass due to summer leaf shedding. PPI was used to derive plant performance estimators for both pulse (maximum value reached by PPI, PPImax) and interpulse phase (duration of the exhaustion phase, Durep, when drought constrains PPI below the plant carbon compensation point determining carbon starvation). For each species the ratio between PPImax and Durep (named PPIred) was used as an index of plant performance. The reduced rainfall regime mainly decreased the performances of the dominant species C. monspeliensis, both limiting PPImax and extending Durep. Under both natural and the manipulated rainfall regime, PPIred was proportional to plant success, measured as the cover degree variation rate of the species. This result suggests that a mechanistic approach using functional traits to quantify the different performance of co‐occurring species can be used to investigate 1) the drivers of the medium‐term changes in species abundance and 2) the processes responsible for change in plant community composition under climate change.

Soils are being degraded at an alarming rate and thereby also crucial ecosystem goods and services. Nitrogen (N) enrichment is a major driver of this degradation. While the negative impacts of N enrichment on vegetation are well known globally, those on various ecological interactions, and on ecosystem functioning, remain largely unknown. Because Mediterranean ecosystems are N limited, they are good model systems for evaluating how N enrichment impacts not only vegetation but also ecological partnerships and ecosystem functioning. Using a 7-year N-manipulation (dose and form) field experiment running in a Mediterranean Basin maquis located in a region with naturally low ambient N deposition (<4kgNha(-1)y(-1)), we assessed the impacts of the N additions on (i) the dominant plant species (photosynthetic N-use efficiency); (ii) plant-soil ecological partnerships with ectomycorrhiza and N-fixing bacteria; and (iii) ecosystem degradation (plant-soil cover, biological mineral weathering and soil N fixation). N additions significantly disrupted plant-soil cover, plant-soil biotic interactions, and ecosystem functioning compared with ambient N deposition conditions. However, the higher the ammonium dose (alone or with nitrate), the more drastic these disruptions were. We report a critical threshold at 20-40kg ammonium ha(-1)y(-1) whereby severe ecosystem degradation can be expected. These observations are critical to help explain the mechanisms behind ecosystem degradation, to describe the collective loss of organisms and multifunction in the landscape, and to predict potential fragmentation of Mediterranean maquis under conditions of unrelieved N enrichment. Copyright (c) 2017 John Wiley & Sons, Ltd.

A transient state canopy-chamber was developed to monitor CO2 exchange of shrubland ecosystems. The chamber covered 0.64 m2 and it was modular with a variable height. Several tests were carried out to check the potential errors in the flux estimates due to leakages and the environment modifications during the measurements inside the chamber. The laboratory leakages test showed an error below 1% of the flux; the temperature increases inside the chamber were below 1.3 °C at different light intensity and small pressure changes. The radial blowers inside the chamber created different wind speed at different chamber height, with faster speed at the top of the chamber and the minimum wind speed that was recorded at soil level, preventing detectable effects on soil CO2 emission rates. Moreover, the chamber was tested for two years in a semi-arid Mediterranean garrigue, identifying a strong seasonality of CO2 fluxes with the highest rates during spring and lowest rates recorded during the hot dry non-vegetative summer.