Papers by Elisa Pellegrini
Plant and Soil, 2023
Background and aims The root barrier to radial O 2 loss is a trait induced during soil flooding r... more Background and aims The root barrier to radial O 2 loss is a trait induced during soil flooding restricting oxygen loss from the roots to the anoxic soil. It can also restrict radial water loss, potentially providing tolerance towards drought during conditions of water deficit. Several root traits (aerenchyma and xylem vessels area) respond in a similar way to soil flooding and low soil water potentials. Therefore, we hypothesised that root acclimations to soil flooding prime plants to withstand conditions of water deficit. Methods We raised plants in hydroponics mimicking contrasting soil water conditions (aerated controls for well-watered soils; stagnant, deoxygenated
Physiologia Plantarum, 2023
Plant roots are exposed to hypoxia in waterlogged soils, and they are further challenged by speci... more Plant roots are exposed to hypoxia in waterlogged soils, and they are further challenged by specific phytotoxins produced by microorganisms in such conditions. One such toxin is hexanoic acid (HxA), which, at toxic levels, causes a strong decline in root O 2 consumption. However, the mechanism underlying this process is still unknown. We treated pea (Pisum sativum L.) roots with 20 mM HxA at pH 5.0 and
Functional Plant Biology, 2023
Adequate tissue O 2 supply is crucial for plant function. We aimed to identify the environmental ... more Adequate tissue O 2 supply is crucial for plant function. We aimed to identify the environmental conditions and plant characteristics that affect plant tissue O 2 status. We extracted data and performed meta-analysis on >1500 published tissue O 2 measurements from 112 species. Tissue O 2 status ranged from anoxic conditions in roots to >53 kPa in submerged, photosynthesising shoots. Using information-theoretic model selection, we identified 'submergence', 'light', 'tissue type' as well as 'light × submergence' interaction as significant drivers of tissue O 2 status. Median O 2 status were especially low (<50% of atmospheric equilibrium) in belowground rhizomes, potato (Solanum tuberosum) tubers and root nodules. Mean shoot and root O 2 were~25% higher in light than in dark when shoots had atmospheric contact. However, light showed a significant interaction with submergence on plant O 2 , with a submergence-induced 44% increase in light, compared with a 42% decline in dark, relative to plants with atmospheric contact. During submergence, ambient water column O 2 and shoot tissue O 2 correlated stronger in darkness than in light conditions. Although use of miniaturised Clark-type O 2 electrodes has enhanced understanding of plant O 2 dynamics, application of non-invasive methods in plants is still lacking behind its widespread use in mammalian tissues.
Applied science, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Journal of Experimental Botany, 2023
Excess water can induce flooding stress resulting in yield loss of crops, even in wetland plants ... more Excess water can induce flooding stress resulting in yield loss of crops, even in wetland plants such as rice. However, traits from species of wild Oryza have already been used to improve tolerance to abiotic stress in cultivated rice. This study aimed to establish root responses to sudden soil flooding among 8 wild relatives of rice with different habitat preferences benchmarked against 3 genotypes of O. sativa. Plants were raised in hydroponics, mimicking drained or flooded soils, to assess the plasticity of adventitious roots. Traits included were apparent permeance (PA) to O2 of the outer part of the roots, radial water loss (RWL), tissue porosity, apoplastic barriers in the exodermis and root anatomical traits. These were analysed using a plasticity index and hierarchical clustering based on principal components analysis. For example, O. brachyantha, a wetland species, possessed very low tissue porosity compared to other wetland species, whereas dryland species O. latifolia and O. granulata exhibited significantly lower plasticity compared to wetland species and clustered in their own group. Most species clustered according to growing conditions based on PA, RWL, root porosity and key anatomical traits, indicating strong anatomical and physiological responses to sudden soil flooding.
Plant and Soil, 2022
Aims
Root tissue water can be lost to the dry topsoil via radial water loss (RWL) resulting in ro... more Aims
Root tissue water can be lost to the dry topsoil via radial water loss (RWL) resulting in root shrinking and loss of contact with the rhizosphere. The root barrier to radial oxygen loss (ROL) has been shown to restrict RWL, therefore we hypothesized that the inducible barrier can be formed as a response to low soil water potential and play a role, together with other root traits, in restricting RWL.
Methods
Rice and wheat were grown in hydroponics with contrasting water potential to diagnose ROL barrier formation and to explore how key root traits (ROL barrier, root diameter, root porosity) affect RWL. Moreover, we developed a numerical model predicting RWL as a function of root diameter, root porosity and presence of a barrier to ROL.
Results
Methylene blue staining showed that low water potential induced a ROL barrier formation in roots of rice, and also resulted in an apoplastic barrier, as identified by the apoplastic tracer periodic acid. The barrier significantly restricted RWL, but root diameter and tissue porosity also influenced RWL. Our numerical model was able to reflect the empirical data and clearly demonstrated that thick roots and a barrier to ROL restricts RWL while cortical porosity accelerates RWL.
Conclusions
Our modelling approach highlighted that increase in root tissue porosity, a common response to drought, conserves water when new roots are formed, but the higher desiccation risk related to high-porosity roots can be effectively counteracted by forming thick roots or even better, by a barrier to ROL.
Frontiers in Environmental Science, 2022
Soil salinization caused by sea level rise threatens coastal agricultural soils and geochemically... more Soil salinization caused by sea level rise threatens coastal agricultural soils and geochemically important wetlands worldwide. The aim of this review is to outline expected changes in soil biological activity by discussing the combined effects of salt stress and flooding on plants productivity and soil microbial communities, which determine consequences on fluxes of C, N and P. Finally, it outlines the expected repercussions on greenhouse gases emissions. The prediction of outcomes is made difficult by the concomitant and sometimes contrasting actions of flooding and seawater intrusion on partly acclimated and non-acclimated environments. Non-salt acclimated plants suffer from osmotic stress, but also from reduced O 2 solubility. Microbial biomass declines with increasing salinity and microbial communities shift in composition. Large concentrations of Cl − inhibit nitrification, but salinity stimulates N 2 O fluxes. Impacts on C mineralisation rates is variable but enhanced by the larger availability of terminal electron acceptors. The reduction of Fe combined with that of SO 4 2− could enhance P mobility. Salinization affects methanogenesis which is constrained in favour of SO 4 2− reduction. Consequences are largely site specific and difficult to predict because of the complex network of processes occurring simultaneously in different compartments (i.e., soil, microbiome, vegetation). The distinction between short and long term effects is also important. A reliable prediction of outcomes at a planetary scale will only result from more precise inventories and monitoring of areas displaying specific similarities and from the implementation from these well-defined data sets of specifically devised models whose results can be finally combined on a weighted basis.
Plants, 2022
The stress gradient hypothesis (SGH) states that plant-plant interactions shift from competition ... more The stress gradient hypothesis (SGH) states that plant-plant interactions shift from competition to facilitation in increasing stress conditions. In salt marshes, edaphic properties can weaken the application of the SGH by amplifying the intensity of flooding and controlling plant zonation. We identified facilitative and competitive interactions along flooding gradients and tested the role of edaphic properties in exacerbating stress and shaping plant-plant interactions. Morphological traits of two target halophytes (Limonium narbonense and Sarcocornia fruticosa), flooding intensity, soil texture and soil organic C were recorded. The relative plant fitness index was assessed for the two species based on the relative growth in plurispecific rather than monospecific plant communities. Plant fitness increased with increasing stress supporting the SGH. L. narbonense showed larger fitness in plurispecific stands whereas S. fruticosa performed better in conspecific stands. Significant intra- or interspecific interactions were observed along the stress gradient defined by the combination of flooding and clay content in soil. When considering the limited soil organic C as stressor, soil properties were more important than flooding in defining plant-plant interactions. We highlight the need for future improvements of the SGH approach by including edaphic stressors in the model and their possible interactions with the main abiotic drivers of zonation.
Geoderma, 2022
In saltmarsh soils, humic acids (HA) are involved in geochemically important redox processes. The... more In saltmarsh soils, humic acids (HA) are involved in geochemically important redox processes. The electron donating capacity (EDC) of HA depends on their molecular structure, but also reflects the intensity of biological reduction in tidal environments. We examined twelve soils in three saltmarshes located along a geographical gradient and applied a specific sequential extraction procedure for the isolation of HA fractions bound (BHA) or not (FHA) to the mineral matrix by Ca2+ bridges, and investigated the relationships of their properties, in particular their EDC, with the biogeochemical characteristics of the soils. Spectroscopic assessment was carried out by UV–vis, FTIR and 13C NMR, quantification and characterization of radicals was performed by electron paramagnetic resonance (EPR) spectroscopy. The EDC was determined by using the 2,2′-azinobis-(3-ethylbenzothiazolinesulfonic acid) (ABTS) decolorization assay and experimental data were fitted to a biphasic model to calculate the contributions of the fast and slow reactions to electron transfer. The results confirmed that the two HA fractions possess different structural characteristics and that BHA present higher EDC values compared to FHA. The EDC of both fractions is strongly related to the geochemical characteristics of soils, and represents an easily measured and highly informative parameter to understand mechanisms affecting redox processes in transitional environments.
Biological Invasions, 2022
Exotic plant invasions are considered one of the major threats to biodiversity causing important ... more Exotic plant invasions are considered one of the major threats to biodiversity causing important impacts at the population, community, and ecosystem levels. Understanding the drivers of plant invasions across multiple spatial and temporal scales often requires a landscape approach. The effect of landscape composition on biological invasion has been extensively studied, whereas landscape configuration effects were seldom considered or the analyses were limited to single species. Here, we aimed to analyze how the expansion of urban and agricultural areas can affect exotic species richness (both neophytes and archaeophytes) at three spatial scales, namely regional (scale: 37.5 km2), landscape (scale: 7.1 km2) and local (scale: 100 m2). We considered the possible contribution of urban and agricultural areas both in terms of composition (i.e. habitat cover) and configuration (i.e. shape complexity of patches). First, we found that increasing urbanization coupled with high shape complexity of urban elements were major drivers of both neophyte and archaeophyte invasions across heterogeneous landscapes. In particular, shape complexity seemed to be a key driver of plant invasions at large spatial scale, whereas the type of recipient habitat and urban cover determined the exotic success at the patch level. Second, archaeophytes were also affected by agriculture land use, i.e. agricultural patches shape complexity increased their spread at both regional and landscape scales. High shape complexity of highly disturbed habitats is expected to increase the exchange surface that exotic plant use to spread their propagules across the landscape mosaics. Our findings suggest that urban planning aimed at curbing urban fragmentation by both reducing shape complexity and diffuse urban sprawl might greatly improve the resistance of landscapes to biological invasions.
Ecological Indicators, 2021
Sand shore ecosystems are extremely vulnerable to alien plant invasions. While most of the abioti... more Sand shore ecosystems are extremely vulnerable to alien plant invasions. While most of the abiotic drivers of alien success have been identified, less is known on the role of biological processes driving the invasion. Studying the interactions between alien and native plant communities across different habitats and along the ecological succession (i.e. community maturity) can elucidate the dynamics of alien invasions in dune systems.
In this study, we sampled alien and native plant communities in 100 patches across 10 natural coastal landscapes in NE Italy. The patches represented three main habitat types (foredune, backdune and salt marsh, which differ in terms of sea storm-related disturbance and soil salinity) distributed along a gradient of community maturity (i.e. number of years since the plant community was completely eroded by a sea storm). We analysed the effects of alien/native status, habitat type and maturity on species richness and colonization potential of plant species pools. Colonization potential was estimated by applying for the first time on plant data a species-habitat network approach, which allowed us to assess in detail the effect of each plant community on the others.
In backdune habitats, alien plant species richness was negatively related with community maturity, which in turn had a positive effect on native species richness. Colonization potential was positively influenced by age for native communities and negatively for alien communities in salt marshes. Among habitat types, backdune patches were also particularly prone to alien invasions and very efficient donors of alien plants to other patches. Salt marshes were in general very resistant to invasion but potentially acting as secondary reservoirs for some backdune alien species.
This study identified backdune habitats as key nodes for alien plant introduction and spread in coastal ecosystems, underlining the importance of maintaining mature undisturbed patches as a barrier to alien invasions. This information could prove pivotal in optimizing monitoring and management efforts of alien plant species in these ecosystems, as well as in conservation prioritization.
Plants
In flooded soils, an efficient internal aeration system is essential for root growth and plant su... more In flooded soils, an efficient internal aeration system is essential for root growth and plant survival. Roots of many wetland species form barriers to restrict radial O2 loss (ROL) to the rhizosphere. The formation of such barriers greatly enhances longitudinal O2 diffusion from basal parts towards the root tip, and the barrier also impedes the entry of phytotoxic compounds produced in flooded soils into the root. Nevertheless, ROL from roots is an important source of O2 for rhizosphere oxygenation and the oxidation of toxic compounds. In this paper, we review the methodological aspects for the most widely used techniques for the qualitative visualization and quantitative determination of ROL from roots. Detailed methodological approaches, practical set-ups and examples of ROL from roots with or without barriers to ROL are included. This paper provides practical knowledge relevant to several disciplines, including plant–soil interactions, biogeochemistry and eco-physiological aspec...
Scientific Reports, 2021
Unveiling the processes driving exotic plant invasion represent a central issue in taking decisio... more Unveiling the processes driving exotic plant invasion represent a central issue in taking decisions aimed at constraining the loss of biodiversity and related ecosystem services. The invasion success is often linked to anthropogenic land uses and warming due to climate change. We studied the responses of native versus casual and naturalised exotic species richness to land uses and climate at the landscape level, relying on a large floristic survey undertaken in NorthEastern Italy. Both climate and land use drove exotic species richness. Our results suggest that the success of plant invasion at this scale is mainly due to warm climatic conditions and the extent of urban and agricultural land, but with different effects on casual and naturalized exotic species. The occurrence of non-linear trends showed that a small percentage of extensive agricultural land in the landscape may concurrently reduce the number of exotic plant while sustaining native plant diversity. Plant invasion could be potentially limited by land management, mainly focusing on areas with extensive agricultural land use. A more consciousness land management is more and more commonly required by local administrations. According to our results, a shift of intensive to extensive agricultural land, by implementing green infrastructures, seems to be a win-win solution favouring native species while controlling the oversimplification of the flora due to plant invasion.
Journal of Plant Ecology
Aims Among terrestrial ecosystems, coastal sandy dunes are particularly prone to alien plant inva... more Aims Among terrestrial ecosystems, coastal sandy dunes are particularly prone to alien plant invasion. Many studies related the invasion of dune habitats to anthropic causes, but less is known about the role of soil properties and plant traits in plant invasion. In this study we tested the relationships between soil features and alien plant invasion in dune systems, focusing on the interplay between soil nutrients, soil salinity and plant functional traits. Methods Study sites were sandy barrier islands of the Marano and Grado lagoon (northern Adriatic Sea). One hundred plots (4x4 m) were selected within 10 areas according to the main habitats occurring along the ecological gradient of dune system (foredune, backdune and saltmarsh). In each plot we recorded all plant species occurrence and abundance and we collected a soil core. For each soil sample, soil texture, conductivity (as proxy of soil salinity), organic carbon and nitrogen content were analyzed and related to the species n...
Evidence of non-structural carbohydrates-mediated response to flooding and salinity in Limonium narbonense and Salicornia fruticosa, 2020
In plant species, the effects of flooding and salinity are commonly studied under controlled cond... more In plant species, the effects of flooding and salinity are commonly studied under controlled conditions in order to understand their acclimation to environmental stresses. Nevertheless, each stress is usually considered separately and laboratory conditions cannot encompass the complexity of the natural ecosystem, often concealing the true plant response. Our work aimed therefore at studying plant responses to flooding and salinity in the field, focusing on two target halophytes and on their reserve organs, i.e. rhizomes of Limonium narbonense and woody stems of Salicornia fruticosa. The physiological response was investigated measuring non-structural carbohydrates (NSCs) and amino acids (AA), and considering the two growing stages of the species, i.e. the growing and the seed ripening seasons. L. narbonense rhizomes showed a larger amount of starch and all measured osmolytes, i.e. NSCs, AA and proline, compared to S. fruticosa woody stem, where plant response to environmental stress seemed linked chiefly to soluble NSCs. The effects on soluble NSCs were mainly driven by flooding and were influenced by salinity only at low flooding stress. The two species showed a contrasting strategy against flooding and salinity based on soluble NSCs, and with a more intense response during the seed ripening season. Large amount of AA, proline in particular, suggested the involvement of these osmolytes in the salinity tolerance in L. narbonense, regardless to the intensity of the stress.
Journal of Vegetation Science, 2020
Questions
Understanding the mechanisms underlying the impacts of exotic plant invasions is a ce... more Questions
Understanding the mechanisms underlying the impacts of exotic plant invasions is a central issue in plant ecology. Considering the invasion process, any alteration of the nutrient cycle is of fundamental importance. We hypothesized that the woody N‐fixing invasive Amorpha fruticosa is indirectly depleting plant diversity by altering ecosystem functions of riverine grasslands, thus producing a conspicuous shift in species’ composition.
Location
Temperate lowland riparian areas of North‐East Italy
Methods
In 12 sites, we selected uninvaded, partially invaded, and invaded grasslands (36 plots). In each plot, we performed a vegetation relevé, measured main A. fruticosa growth traits, light transmittance and soil features. We studied the effects of the invasion of A. fruticosa on grassland properties and plant diversity, examining the interactions between soil nutrient cycles, light availability and plant diversity.
Results
Increased abundance of A. fruticosa affected main soil properties (i.e. increase in soil mineralization and nitrification) and light availability (i.e. decrease in light). The δ15N of soil organic matter was strongly related to A. fruticosa basal area, thus supporting the hypothesis of an increase in soil nitrogen (N) availability due to invasion by the N‐fixer. Plant taxonomical and functional diversity decreased significantly as A. fruticosa cover increased. Plant diversity was more related with N than light availability or soil organic carbon. Similarly, the shift in species composition (i.e. beta‐diversity) of invaded grasslands was related to increased soil nitrification rates.
Conclusions
Our findings show how a nitrogen‐fixing invasive plant such as A. fruticosa may influence the main ecosystem properties, causing cascading effects on soil functions, decreasing plant diversity. Alteration of the N cycle represents the key process involved in this plant invasion, suggesting that further studies should focus on potential solutions to mitigate the soil N supply, curb the invasion and restore plant diversity of these riverine grasslands.
Environmental Toxicology and Chemistry, 2019
The aptness of the ∑SEM/AVS (Simultaneously Extracted Metals/Acid Volatile Sulfides) index to asc... more The aptness of the ∑SEM/AVS (Simultaneously Extracted Metals/Acid Volatile Sulfides) index to ascertain environmental risk from potentially toxic elements in calcareous saltmarsh soils was tested using Structural Equation Modelling. This technique allows to detect both direct and indirect relationships among AVS, SEM and other soil variables, representing results in a graphical view. The dataset included 90 soil samples from 21 different sites belonging to six different saltmarshes and featured a wide range of soil chemico-physical properties. Variables included in the a priori model were hydroperiod, pH, soil redox potential, labile organic carbon, carbonates, total Fe and total amount of potentially toxic elements (PTE). The best optimised model pointed out the main soil properties which affect AVS accumulation and SEM speciation in these soils. Effect plots of AVS and SEM calculated with the partial linear mixed-effects models included in the piecewise Structural Equation Modelling showed a significant and positive influence of pH and of carbonates on AVS and a highly significant effect of carbonates and labile organic carbon on SEM. Single SEM components were also considered separately in order to define potential contributions of labile organic carbon or carbonates as alternative binding phases. Simultaneously extracted Cu, Ni and Zn resulted preferentially bound to carbonates followed by labile organic carbon, whereas Pb and Cd were easily bound to labile organic carbon.
Gortania, 2018
Viene presentata la checklist aggiornata delle specie esotiche per il territorio del Friuli Venez... more Viene presentata la checklist aggiornata delle specie esotiche per il territorio del Friuli Venezia Giulia, comprensiva
di indicazioni sullo status delle specie, diffusione nel territorio, dominanza, invasività potenziale e di altri caratteri funzionali.
Complessivamente la lista annovera 341 specie e 23 sottospecie delle quali 185 possiedono lo status di casuale, 119 di
naturalizzata, 30 di invasiva e 7 di trasformatrice. Sono state effettuate alcune elaborazioni relativamente al comportamento
delle aliene in base ai caratteri funzionali e alla loro distribuzione in regione. Vengono poi riportate le schede monografiche
delle specie aliene trasformatrici e invasive comprensive di mappe distributive.
The updated checklist of the exotic species of the Friuli Venezia Giulia territory is presented, including indications on
the status of the species, diffusion in the territory, dominance, potential invasiveness and other functional traits. The list includes
341 species and 23 subspecies of which 185 have the status of casuals, 119 of naturalized, 30 invasive and 7 of transformers. Some
elaborations have been made regarding the behavior of the aliens on the basis of functional traits and their distribution in the
region. The monographic sheets of the alien and transformers invasive species including distribution maps are then reported.
Journal of Soils and Sediments, 2019
Purpose The use of eco-friendly and cost-effective adsorbent materials in the remediation of soil... more Purpose The use of eco-friendly and cost-effective adsorbent materials in the remediation of soils contaminated by potentially toxic elements (PTE) is a sustainable way of reducing the transfer of these elements into the food chain. However, an evaluation of the potential of natural zeolites to immobilize toxic elements in contaminated soils was required to enable their efficient use. Materials and methods The effect of natural zeolite (Stilbite-Stellerite) from the Munella area (Northern Albania), added at rates ranging from 1.25 to 10 % w/w on a contaminated soil was investigated in a greenhouse pot experiment with ryegrass (Lolium multiflorum L.) and by selective extractions. PTE availability for plants was assessed either as their accumulation in plant tissue or by DTPA-extraction. Oral bio-accessibility was estimated by the in vitro PBET method and the mobility and consequent potential risk of leaching by the USEPA TLCP method. The effect of zeolites on soil properties (pH, electrical conductivity-EC, organic C, and total N) was also investigated. A five steps sequential extraction procedure (SEP) was applied to investigate the immobilization mechanism. Results and discussion The addition of 2.5% w/w of natural zeolites caused a significant decrease of PTE mobility, but to observe a significant reduction of DTPA-extractable metals, it was necessary to reach 10% addition rate. In contrast, plant growth showed a gradual increase with addition rate and a corresponding decrease of concentration of PTE in plant tissue. Correlation between DTPA-extractable PTE and their concentration in both root and shoot plant tissue was rather poor. Human hazard due to soil ingestion (PBET method) changed only for Cu and Zn in the gastric phase with 1.25 and 5% addition rate respectively, whereas decreased for Cu and Zn at 5% rate in the Intestinal phase. The results of SEP support the hypothesis that the main mechanism involved in metals fixation are as follows: (1) insolubilization by pH rise, (2) adsorption on Fe/Mn oxides (3) increase of cation exchange retention, (4) organic complexation. Conclusions The results of this work suggest that the addition of natural zeolites from the Munella area (AL) is a sustainable practice to reduce the environmental impact of PTE contaminated soils, but an assessment on the longevity of their immobili-zation need to be evaluated in the long-term perspectives.
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Papers by Elisa Pellegrini
Root tissue water can be lost to the dry topsoil via radial water loss (RWL) resulting in root shrinking and loss of contact with the rhizosphere. The root barrier to radial oxygen loss (ROL) has been shown to restrict RWL, therefore we hypothesized that the inducible barrier can be formed as a response to low soil water potential and play a role, together with other root traits, in restricting RWL.
Methods
Rice and wheat were grown in hydroponics with contrasting water potential to diagnose ROL barrier formation and to explore how key root traits (ROL barrier, root diameter, root porosity) affect RWL. Moreover, we developed a numerical model predicting RWL as a function of root diameter, root porosity and presence of a barrier to ROL.
Results
Methylene blue staining showed that low water potential induced a ROL barrier formation in roots of rice, and also resulted in an apoplastic barrier, as identified by the apoplastic tracer periodic acid. The barrier significantly restricted RWL, but root diameter and tissue porosity also influenced RWL. Our numerical model was able to reflect the empirical data and clearly demonstrated that thick roots and a barrier to ROL restricts RWL while cortical porosity accelerates RWL.
Conclusions
Our modelling approach highlighted that increase in root tissue porosity, a common response to drought, conserves water when new roots are formed, but the higher desiccation risk related to high-porosity roots can be effectively counteracted by forming thick roots or even better, by a barrier to ROL.
In this study, we sampled alien and native plant communities in 100 patches across 10 natural coastal landscapes in NE Italy. The patches represented three main habitat types (foredune, backdune and salt marsh, which differ in terms of sea storm-related disturbance and soil salinity) distributed along a gradient of community maturity (i.e. number of years since the plant community was completely eroded by a sea storm). We analysed the effects of alien/native status, habitat type and maturity on species richness and colonization potential of plant species pools. Colonization potential was estimated by applying for the first time on plant data a species-habitat network approach, which allowed us to assess in detail the effect of each plant community on the others.
In backdune habitats, alien plant species richness was negatively related with community maturity, which in turn had a positive effect on native species richness. Colonization potential was positively influenced by age for native communities and negatively for alien communities in salt marshes. Among habitat types, backdune patches were also particularly prone to alien invasions and very efficient donors of alien plants to other patches. Salt marshes were in general very resistant to invasion but potentially acting as secondary reservoirs for some backdune alien species.
This study identified backdune habitats as key nodes for alien plant introduction and spread in coastal ecosystems, underlining the importance of maintaining mature undisturbed patches as a barrier to alien invasions. This information could prove pivotal in optimizing monitoring and management efforts of alien plant species in these ecosystems, as well as in conservation prioritization.
Understanding the mechanisms underlying the impacts of exotic plant invasions is a central issue in plant ecology. Considering the invasion process, any alteration of the nutrient cycle is of fundamental importance. We hypothesized that the woody N‐fixing invasive Amorpha fruticosa is indirectly depleting plant diversity by altering ecosystem functions of riverine grasslands, thus producing a conspicuous shift in species’ composition.
Location
Temperate lowland riparian areas of North‐East Italy
Methods
In 12 sites, we selected uninvaded, partially invaded, and invaded grasslands (36 plots). In each plot, we performed a vegetation relevé, measured main A. fruticosa growth traits, light transmittance and soil features. We studied the effects of the invasion of A. fruticosa on grassland properties and plant diversity, examining the interactions between soil nutrient cycles, light availability and plant diversity.
Results
Increased abundance of A. fruticosa affected main soil properties (i.e. increase in soil mineralization and nitrification) and light availability (i.e. decrease in light). The δ15N of soil organic matter was strongly related to A. fruticosa basal area, thus supporting the hypothesis of an increase in soil nitrogen (N) availability due to invasion by the N‐fixer. Plant taxonomical and functional diversity decreased significantly as A. fruticosa cover increased. Plant diversity was more related with N than light availability or soil organic carbon. Similarly, the shift in species composition (i.e. beta‐diversity) of invaded grasslands was related to increased soil nitrification rates.
Conclusions
Our findings show how a nitrogen‐fixing invasive plant such as A. fruticosa may influence the main ecosystem properties, causing cascading effects on soil functions, decreasing plant diversity. Alteration of the N cycle represents the key process involved in this plant invasion, suggesting that further studies should focus on potential solutions to mitigate the soil N supply, curb the invasion and restore plant diversity of these riverine grasslands.
di indicazioni sullo status delle specie, diffusione nel territorio, dominanza, invasività potenziale e di altri caratteri funzionali.
Complessivamente la lista annovera 341 specie e 23 sottospecie delle quali 185 possiedono lo status di casuale, 119 di
naturalizzata, 30 di invasiva e 7 di trasformatrice. Sono state effettuate alcune elaborazioni relativamente al comportamento
delle aliene in base ai caratteri funzionali e alla loro distribuzione in regione. Vengono poi riportate le schede monografiche
delle specie aliene trasformatrici e invasive comprensive di mappe distributive.
The updated checklist of the exotic species of the Friuli Venezia Giulia territory is presented, including indications on
the status of the species, diffusion in the territory, dominance, potential invasiveness and other functional traits. The list includes
341 species and 23 subspecies of which 185 have the status of casuals, 119 of naturalized, 30 invasive and 7 of transformers. Some
elaborations have been made regarding the behavior of the aliens on the basis of functional traits and their distribution in the
region. The monographic sheets of the alien and transformers invasive species including distribution maps are then reported.
Root tissue water can be lost to the dry topsoil via radial water loss (RWL) resulting in root shrinking and loss of contact with the rhizosphere. The root barrier to radial oxygen loss (ROL) has been shown to restrict RWL, therefore we hypothesized that the inducible barrier can be formed as a response to low soil water potential and play a role, together with other root traits, in restricting RWL.
Methods
Rice and wheat were grown in hydroponics with contrasting water potential to diagnose ROL barrier formation and to explore how key root traits (ROL barrier, root diameter, root porosity) affect RWL. Moreover, we developed a numerical model predicting RWL as a function of root diameter, root porosity and presence of a barrier to ROL.
Results
Methylene blue staining showed that low water potential induced a ROL barrier formation in roots of rice, and also resulted in an apoplastic barrier, as identified by the apoplastic tracer periodic acid. The barrier significantly restricted RWL, but root diameter and tissue porosity also influenced RWL. Our numerical model was able to reflect the empirical data and clearly demonstrated that thick roots and a barrier to ROL restricts RWL while cortical porosity accelerates RWL.
Conclusions
Our modelling approach highlighted that increase in root tissue porosity, a common response to drought, conserves water when new roots are formed, but the higher desiccation risk related to high-porosity roots can be effectively counteracted by forming thick roots or even better, by a barrier to ROL.
In this study, we sampled alien and native plant communities in 100 patches across 10 natural coastal landscapes in NE Italy. The patches represented three main habitat types (foredune, backdune and salt marsh, which differ in terms of sea storm-related disturbance and soil salinity) distributed along a gradient of community maturity (i.e. number of years since the plant community was completely eroded by a sea storm). We analysed the effects of alien/native status, habitat type and maturity on species richness and colonization potential of plant species pools. Colonization potential was estimated by applying for the first time on plant data a species-habitat network approach, which allowed us to assess in detail the effect of each plant community on the others.
In backdune habitats, alien plant species richness was negatively related with community maturity, which in turn had a positive effect on native species richness. Colonization potential was positively influenced by age for native communities and negatively for alien communities in salt marshes. Among habitat types, backdune patches were also particularly prone to alien invasions and very efficient donors of alien plants to other patches. Salt marshes were in general very resistant to invasion but potentially acting as secondary reservoirs for some backdune alien species.
This study identified backdune habitats as key nodes for alien plant introduction and spread in coastal ecosystems, underlining the importance of maintaining mature undisturbed patches as a barrier to alien invasions. This information could prove pivotal in optimizing monitoring and management efforts of alien plant species in these ecosystems, as well as in conservation prioritization.
Understanding the mechanisms underlying the impacts of exotic plant invasions is a central issue in plant ecology. Considering the invasion process, any alteration of the nutrient cycle is of fundamental importance. We hypothesized that the woody N‐fixing invasive Amorpha fruticosa is indirectly depleting plant diversity by altering ecosystem functions of riverine grasslands, thus producing a conspicuous shift in species’ composition.
Location
Temperate lowland riparian areas of North‐East Italy
Methods
In 12 sites, we selected uninvaded, partially invaded, and invaded grasslands (36 plots). In each plot, we performed a vegetation relevé, measured main A. fruticosa growth traits, light transmittance and soil features. We studied the effects of the invasion of A. fruticosa on grassland properties and plant diversity, examining the interactions between soil nutrient cycles, light availability and plant diversity.
Results
Increased abundance of A. fruticosa affected main soil properties (i.e. increase in soil mineralization and nitrification) and light availability (i.e. decrease in light). The δ15N of soil organic matter was strongly related to A. fruticosa basal area, thus supporting the hypothesis of an increase in soil nitrogen (N) availability due to invasion by the N‐fixer. Plant taxonomical and functional diversity decreased significantly as A. fruticosa cover increased. Plant diversity was more related with N than light availability or soil organic carbon. Similarly, the shift in species composition (i.e. beta‐diversity) of invaded grasslands was related to increased soil nitrification rates.
Conclusions
Our findings show how a nitrogen‐fixing invasive plant such as A. fruticosa may influence the main ecosystem properties, causing cascading effects on soil functions, decreasing plant diversity. Alteration of the N cycle represents the key process involved in this plant invasion, suggesting that further studies should focus on potential solutions to mitigate the soil N supply, curb the invasion and restore plant diversity of these riverine grasslands.
di indicazioni sullo status delle specie, diffusione nel territorio, dominanza, invasività potenziale e di altri caratteri funzionali.
Complessivamente la lista annovera 341 specie e 23 sottospecie delle quali 185 possiedono lo status di casuale, 119 di
naturalizzata, 30 di invasiva e 7 di trasformatrice. Sono state effettuate alcune elaborazioni relativamente al comportamento
delle aliene in base ai caratteri funzionali e alla loro distribuzione in regione. Vengono poi riportate le schede monografiche
delle specie aliene trasformatrici e invasive comprensive di mappe distributive.
The updated checklist of the exotic species of the Friuli Venezia Giulia territory is presented, including indications on
the status of the species, diffusion in the territory, dominance, potential invasiveness and other functional traits. The list includes
341 species and 23 subspecies of which 185 have the status of casuals, 119 of naturalized, 30 invasive and 7 of transformers. Some
elaborations have been made regarding the behavior of the aliens on the basis of functional traits and their distribution in the
region. The monographic sheets of the alien and transformers invasive species including distribution maps are then reported.