Leersia Oryzoides Research Articles

Notes floristiques. Observations faites au Luxembourg (2022-2023)

The most important records of vascular plant species made in Luxembourg in 2022 and 2023 are presented. In total, 122 taxa are mentioned. Adiantum aleuticum, Amaranthus blitoides, Bidens radiata, Centranthus calcitrapae, Chiastophyllum oppositifolium, Dipsacus laciniatus, Hibiscus trionum, Lagurus ovatus, Lepidium didymum, Rumex patientia and Sedum hispanicum, as well as the potentially invasive species Erigeron bonariensis, Erigeron karvinskianus, Erigeron sumatrensis and Lysichiton americanus are newly listed species found in Luxembourg. The discoveries of new or confirmed locations for Atriplex nitens, Callitriche obtusangula, Carex brizoides, Dysphania botrys, Filago arvensis, Fumaria parviflora, Hylotelephium telephium subsp. fabaria, Leersia oryzoides, Orchis simia, Panicum barbipulvinatum, Serratula tinctoria and Stachys annua are remarkable. The invasive species Ailanthus altissima, Cochlearia danica, Crassula helmsii, Prunus laurocerasus and Senecio inaequidens are spreading further. The implementation of national action plans for threatened species and habitats, as well as systematic fieldwork carried out over the last years, have resulted in the discoveries of new locations of endangered and/or protected species; other, previously known sites, were confirmed.

The far from miserable flora of the muddy banks downstream the “Misère” forebay of the Upper-Sûre lake in Luxembourg.

A recent survey of the muddy banks of the Upper-Sûre reservoir in Luxembourg led to the discovery of a considerable number of rare vascular plants and bryophytes as well as several insufficiently documented habitats for Luxembourg. Bidens radiata is newly listed for Luxembourg – locally occurring on gravel banks –, Leersia oryzoides has rarely been recorded in Luxembourg, while Panicum barbipulvinatum has only been observed once in 2005. Riccia cavernosa, Riccia huebeneriana and Physcomitrium sphaericum are among the bryological peculiarities. After the water receded, we observed an explosive spread of the uncommon alga Botrydium granulatum, covering large areas with its green globules. The muddy banks are a habitat for specific plant communities with many rare and protected species. Unfortunately, national legislation omits to protect this FFH Annex I habitat “3270 Rivers with muddy banks with Chenopodion rubri p.p. and Bidention p.p. vegetation”.

Współczesna szata roślinna Zalewu Rzeszowskiego (południowo-wschodnia Polska)

This paper presents the results of current research on the vegetation and flora of the Rzeszów Reservoir (SE Poland). The research was carried out in 2016–2019. In the study, the relevés were performed using the Braun-Blaquet method. Based on 147 phytosociological relevés, 21 plant communities belonging to 5 classes (Lemnetea, Potametea, Phragmitetea, Molinio-Arrhenatheretea, and Salicetea purpureae) were identified. Trapetum natantis, Typhetum latifoliae, Typhetum angustifoliae, Glycerietum maximae, Leersietum oryzoidis, Salicetum triandro- viminalis were the most common, whereas Spirodeletum polyrhizae, Utricularia vulgaris, Potametum natantis, Eleocharitetum palustris, and Caricetum gracilis were rare communities. Noteworthy is the association Trapetum natantis, a rare and endangered plant community whose population is developing dynamically in the reservoir. The vascular flora of the Rzeszów Reservoir is represented by 334 taxa belonging to 66 families, including two strictly protected species (Dianthus armeria, Trapa natans), one partially protected species (Epipactis helleborine), and four species from the Polish red list (Trapa natans – VU, Potamogeton obtusifolius, Utricularia vulgaris, Leersia oryzoides – NT).

Diversidade de plantas daninhas em função do preparo do solo e da aplicação do herbicida glufosinato de amônio

ABSTRACT Farmers in Indonesia generally spray herbicides to control weeds and use tillage during the early stages of crop cultivation; consequently, these activities affect the weed composition and diversity. This study aimed to evaluate the dominance and diversity index of weeds and obtain abundance correlations according to the soil chemical characteristics, as well as the effect of the ammonium glufosinate herbicide, in different tillage systems. A non-factorial randomized block design was used, consisting of no-tillage (NT), 1-time tillage (T1) and 2-times tillage (T2), with three replications. The Cyperus rotundus and Ageratum conyzoides weed species were dominant in the tillages. The diversity indices were 2.261, 2.196 and 2.234 (moderate/stable condition), respectively for the NT, T1 and T2. For T2, there were increases of 2.82-folds, 41 populations and 2.43-folds, respectively for A. conyzoides, Cynodon dactylon and Euphorbia heterophylla, when compared to NT, while a decrease was observed in grasses for T1 and T2 (50.71 and 26.05 %, respectively). Moreover, there was a positive and significant correlation for E. heterophylla according to the soil cation exchange capacity (0.727). In contrast, four new weed species (Glyceria maxima, Leersia oryzoides, Scoparia dulcis and Anthoxanthum oculatum) were found due to the ammonium glufosinate application, in the different tillage systems.

Searching for Indicator Species of High Floristic Quality Depressional Wetlands in the US Southern Plains

Floristic Quality Assessment requires compiling a full list of vascular plant species for the wetland. Practitioners may lack the time and taxonomic skills for full-community vegetation surveys, especially when wetlands are large and complex. In this paper we broadly ask whether floristic quality indicator species may exist for wetlands, specifically evaluating indicator species potential for high floristic quality depressional wetlands in the US southern plains. Candidate indicators were identified for a broader context (depressions across Oklahoma prairie ecoregions) and narrower context (depressions in the northern Central Great Plains of Oklahoma) and evaluated based on performance, validity, and robustness criteria. Nine individual species and two species pairs showed exclusivity and ubiquity for high floristic quality, with their value generally improving in the narrower context. However, the overall best indicator (Eleocharis compressa) frequently occurred (> 20 % rate) in lower quality validation sites, and all indicators were lacking in one or more criteria. Combining E. compressa with select other candidates (Ammannia coccinea, Juncus torreyi, Leersia oryzoides) may compensate for weaknesses of individual species but the combinations may rarely be found across the region, suggesting they may not be useful in practice or that high-quality conditions are in fact scarce. Overall, these results offer mixed support for relying on indicator species to rapidly identify or verify high floristic quality depressional wetlands in the US southern plains. We recommend similar studies with larger datasets in other regions and testing other quality levels (low, moderate) before broadly concluding whether floristic quality indicator species may exist for wetlands.

The reproductive strategy of the clonal helophyte Leersia oryzoides (L.) Swartz. in response to variable submergence conditions and different harvest times

Clonal plants can reproduce both sexually and asexually. Selection of reproductive strategies is crucial for the evolution of clonal plants. Nevertheless, little is known about the reproductive strategy of clonal aquatic plants in diverse environments and at different harvest times. In this study, the reproduction of the clonal aquatic plant species Leersia oryzoides (L.) Swartz. was investigated under two different submergence conditions: mesic and flooding in two different years. We collected data concerning specific leaf area (SLA), a growth-related trait, during the growing season in both years. Seed output (total seed mass, seed number and seed mass) and rhizome mass, which reflect sexual reproduction and asexual reproduction, respectively, were measured in the reproductive period. The correlation between sexual reproduction (total seed mass) and asexual propagation (rhizome mass) was subsequently analyzed. The correlations between SLA and each reproductive output—total seed mass and rhizome mass—were explored. Seed output (the seed number and total seed mass) decreased in the second-year harvest (H2) compared to the first-year harvest (H1). Greater seed mass was observed at H2 than at H1 in the flooding treatment. The ratio of sexual to asexual reproductive output increased under flooding and decreased at H2. Generally, the SLA and rhizome mass were not significantly correlated, while a significant negative correlation was detected between SLA and total seed mass across all observations. A nonsignificant correlation between rhizome mass and total seed mass was also detected. A decrease in sexual reproduction can occur over time, although disturbances such as flooding can promote the allocation of reproduction resources to the sexual approach. Leaf functional traits such as SLA may negatively predict the output of sexual reproduction, and the trade-off between SLA and asexual propagation is likely nonexistent. A trade-off between asexual reproduction and sexual reproduction does not exist for L. oryzoides.

Vegetated Ditch Habitats Provide Net Nitrogen Sink and Phosphorus Storage Capacity in Agricultural Drainage Networks Despite Senescent Plant Leaching

The utility of vegetated ditch environments as nutrient sinks in agricultural watersheds is dependent in part on biogeochemical transformations that control plant uptake and release during decomposition. We investigated nitrogen (N) and phosphorus (P) uptake and release across four P enrichment treatments in ditch mesocosms planted with rice cutgrass (Leersia oryzoides) during the summer growing and winter decomposition seasons. Measured N retention and modeled denitrification rates did not vary, but P retention significantly increased with P enrichment. At the end of the growing season, root biomass stored significantly more N and P than aboveground stem and leaf biomass. Decomposition rates were low (<10% organic matter loss) and not affected by P enrichment. Nitrogen and P export during winter did not vary across the P enrichment gradient. Export accounted for <10% of observed summer N uptake (1363 mg m−2), with denitrification potentially accounting for at least 40% of retained N. In contrast, net P retention was dependent on enrichment; in unenriched mesocosms, P uptake and release were balanced (only 25% net retention), whereas net retention increased from 77% to 88% with increasing P enrichment. Our results indicate that vegetated ditch environments have significant potential to serve as denitrification sinks, while also storing excess P in agricultural watersheds.

Florpyrauxifen-benzyl activity on perennial grass weeds found in Louisiana rice production

AbstractA glasshouse study was conducted on the Louisiana State University campus in Baton Rouge, LA, to evaluate the control of brook crowngrass, rice cutgrass, southern watergrass, and water paspalum. Florpyrauxifen-benzyl was applied at 30 g ai ha−1 to each grass species at the 3- to 4-leaf or 1- to 2-stolon stage of growth. Brook crowngrass treated with florpyrauxifen was controlled 71% at 21 d after treatment. Southern watergrass and water paspalum control did not exceed 56% and 36%, respectively, across all evaluations. Rice cutgrass treated with florpyrauxifen did not reach 15% control. Plants treated with florpyrauxifen, except rice cutgrass, displayed reduction in leaf number, stolon number, plant height, and plant fresh weight. These results indicate florpyrauxifen-benzyl can help manage a brook crowngrass infestation and suppress southern watergrass. However, florpyrauxifen-benzyl has little to no activity on water paspalum and rice cutgrass, and other management options should be employed if these weeds are present.

Shallow and deep water aquatic vegetation potential for a midlatitude pool of the Upper Mississippi River System with drawdown

AbstractPrior to navigation dam and levee placement, the Upper Mississippi River (UMR) flowed through a wide floodplain supporting a diverse ecosystem. Diversity was created by variable flood frequencies and water flow, but presently high and static water levels supporting river navigation have caused low diversity of aquatic vegetation in locations within the UMR. A pool‐scale water level drawdown was proposed as a wetland management tool to mimic historic low water flow for UMR Navigation Pool 18, between Oquawka and Keithsburg, IL. The objectives of this research are to determine plant species, density, and diversity expected for a drawdown in Pool 18.A seedbank and propagule assay was used to evaluate drawdown plant species response. Emergence was tested using river bottom substrate samples collected in 2009 from the proposed drawdown area. Samples were treated at two hydrologic levels: shallow (3‐cm depth) and deep (16‐cm depth). Dominant species in the shallow flooded treatment were Gratiola neglecta, Leersia oryzoides, Eleocharis palustris, Sagittaria latifolia, and Ammania coccinea. Deep flooded dominant taxa included G. neglecta, S. latifolia, Vallisneria americana, and A. coccinea. Each treatment indicated a seedbank of moderate diversity with a shallow treatment diversity of D = 0.56 and deep treatment diversity of D = 0.44. Plant density for the shallow flooded treatment was 213 stems/m2 (±112; 95% CI), and deep flooded hydrologic treatment, 206 stems/m2 (±82; 95% CI). It is expected that this drawdown will provide an intermediate ecological disturbance resulting in greater species diversity and density currently lacking in this portion of the Upper Mississippi River System.

Urban wetland seed bank profiles in south-central New York State1,2

Wetlands are important habitats in urban landscapes that reduce flooding and improve water quality, yet urban wetland seed banks are rarely studied. Our main objective was to profile urban wetland seed banks in south-central New York. We exposed sediment cores from four wetlands in Broome County, New York, to flooded and drawdown treatments for 16 mo, and recorded community composition and seedling density. We found high spatial variation in species richness and seedling density among the four sites. Species richness ranged from 28 to 56 species, with sample-based extrapolation (Sest), Jackknife1, and Chao1 analyses estimating similar expected species richness values (Sest projected 37.9–77.0 species, Jackknife1 analysis estimated 40.5–77.8 species, and Chao1 projected 32.2–79.1 species). Mean seedling density ranged from 3,367 seedlings/m2 to 19,132 seedlings/m2. These seed banks were dominated by obligate wetland species (75.8–93.3%). Invasive species comprised a high percentage of seedlings for three wetlands (40.8–80.9%), but not for the fourth site (4.2%). Lythrum salicaria, Typha sp., and Ludwigia palustris were common species based on relative seedling density for three seed banks, while Leersia oryzoides, Schoenoplectus tabernaemontani, and Alisma triviale were common species in the fourth site. Similarity indices between the standing vegetation and their respective seed banks, based on presence/absence data, were low (13–34%). Species richness and seedling densities were within the ranges of natural wetland seed bank studies.

Seasonal Differences in Relationships between Nitrate Concentration and Denitrification Rates in Ditch Sediments Vegetated with Rice Cutgrass.

Increased application of nitrogen (N) fertilizers in agricultural systems contributes to significant environmental impacts, including eutrophication of fresh and coastal waters. Rice cutgrass [ (L.) Sw.] can significantly enhance denitrification potential in agricultural ditch sediments and potentially reduce N export from agricultural watersheds, but relationships with known drivers are not well understood. To address this, we examined effects of nitrate (NO) availability on dinitrogen gas (N) and NO fluxes seasonally. Net denitrification rates were measured as positive N fluxes from vegetated intact sediment cores using membrane inlet mass spectrometry (MIMS). We developed Michaelis-Menten models for N fluxes across NO gradients in the spring, summer, and fall seasons. Summer N models exhibited the highest (maximum amount of net N flux) and (concentration of NO in the overlying water at which the net N flux is half of ), with a maximum production of N of ∼20 mg N m h. Maximum percentage NO retention occurred at 1 mg NO L in the overlying water in all seasons, except summer where maximum retention persisted from 1 to 5 mg NO L. Denitrification rates were strongly correlated with NO uptake by vegetated sediments in spring ( = 0.94, < 0.0001) and summer ( = 0.97, < 0.0001), but low NO uptake in fall and winter resulted in virtually no net denitrification during these seasons. Our results indicate that vegetated ditch sediments may act as effective NO sinks during the growing season. Ditch sediments vegetated with cutgrass not only immobilized a significant fraction of NO entering them but also permanently removed as much as 30 to 40% of the immobilized NO through microbial denitrification.

Bacterial endophytes from rice cut grass (Leersia oryzoides L.) increase growth, promote root gravitropic response, stimulate root hair formation, and protect rice seedlings from disease

Leersia oryzoides, a wild relative of rice (Oryza sativa), may carry potential seed-borne bacterial endophytes which could be used to enhance growth of rice. We hypothesized that seed-associated bacteria from L. oryzoides would be compatible with rice and promote seedling growth, development, and survival. We isolated bacteria from seed of L. oryzoides and checked compatibility with rice as well as Bermuda grass seeds for seedling growth promotion. Internal colonisation of bacteria into root cells was observed by ROS staining and microscopic observation. Growth promoting bacteria were evaluated for IAA production, phosphate solubilization and antifungal activities. Overall, ten bacteria were found to be growth promoting in rice seedlings with effects including restoration of root gravitropic response, increased root and shoot growth, and stimulation of root hair formation. All bacteria were identified by 16S rDNA sequencing. Six bacteria were found to become intracellular in root parenchyma and root hairs in rice and in Bermuda grass seedlings. Six bacteria were able to produce IAA in LB broth with highest (47.06 ± 1.99 μg ml−1) by LTE3 (Pantoea hericii). Nine isolates solubilized phosphate and inhibited at least one soil borne fungal pathogen. Seed bacteria of L. oryzoides are compatible with rice. Many of these bacteria become intracellular, induce root gravitropic response, increase root and shoot growth, and stimulate root hair formation in both rice and Bermuda grass seedlings. Presence of bacteria protects seedlings from soil pathogens during seedling establishment. This research suggests that bioprospecting microbes on near relatives of rice and other crop plants may be a viable strategy to obtain microbes to improve cultivation of crops.

Susceptibility of peruvian watergrass and rice cutgrass to glyphosate under soil moisture variations

Peruvian watergrass and rice cutgrass are important grass weeds in paddy rice in southern Brazil, mainly due to the low efficacy of non-selective herbicides against these species. The objectives of this study were (1) to evaluate the susceptibility of peruvian watergrass to glyphosate under soil moisture variations, (2) to investigate the effect of soil moisture variations in the control efficiency of glyphosate on peruvian watergrass and rice cutgrass, and (3) to determine the leaf blade and stem anatomical features of both species under flood conditions. Three experiments were conducted, two in a greenhouse and one in laboratory conditions. The first experiment was conducted using three soil water contents (field capacity, saturated and flood conditions) and nine doses of glyphosate to evaluate peruvian watergrass control and dry biomass reduction. The same factors and evaluations were used in the second experiment, however with the addition of the rice cutgrass species. Plants of both species, grown under flood conditions, were collected for histological analysis in the third trial. The susceptibility of these grass weeds was greatly reduced under flood conditions, particularly peruvian watergrass. There were anatomical differences between the two species, but these may not influence the efficacy of the chemical control. Their morphological differences are therefore expected to be involved in their tolerance to glyphosate.

Mitigation of atrazine, S-metolachlor, and diazinon using common emergent aquatic vegetation

By the year 2050, the population of the United States is expected to reach over 418 million, while the global population will reach 9.6 billion. To provide safe food and fiber, agriculture must balance pesticide usage against impacts on natural resources. Challenges arise when storms cause runoff to be transported to aquatic receiving systems. Vegetated systems such as drainage ditches and constructed wetlands have been proposed as management practices to alleviate pesticide runoff. Twelve experimental mesocosms (1.3×0.71×0.61m) were filled with sediment and planted with a monoculture of one of three wetland plant species (Typha latifolia, Leersia oryzoides, and Sparganium americanum). Three mesocosms remained unvegetated to serve as controls. All mesocosms were amended with 9.2±0.8μg/L, 12±0.4μg/L, and 3.1±0.2μg/L of atrazine, metolachlor, and diazinon, respectively, over a 4hr hydraulic retention time to simulate storm runoff. Following the 4hr amendment, non-amended water was flushed through mesocosms for an additional 4hr. Outflow water samples were taken hourly from pre-amendment through 8hr, and again at 12, 24, 48, 72, and 168hr post-amendment. L. oryzoides and T. latifolia had mean atrazine, metolachlor, and diazinon retentions from 51%–55% for the first 4hr of the experiment. Aside from S. americanum and atrazine (25% retention), unvegetated controls had the lowest pesticide retention (17%–28%) of all compared mesocosms. While native aquatic vegetation shows promise for mitigation of pesticide runoff, further studies increasing the hydraulic retention time for improved efficiency should be examined.

Urban Wetland Characterization in South-Central New York State

Urban wetlands can serve to reduce flooding and improve water quality, yet we know little about their plant communities. Our study aims to characterize the vegetation and soil parameters of these important ecosystems, and to compare these features to those of previously sampled natural wetlands in south-central New York. Vegetation and soil characteristics were sampled in eight urban wetlands and compared to six forested wetlands, five scrub-shrub wetlands, and seven emergent wetlands. Urban sites had significantly lower species richness and a higher percent cover of invasives, including Typha x glauca, Phalaris arundinacea, and Lythrum salicaria. However, non-invasive species were also common in urban flora, including Leersia oryzoides, Ludwigia palustris, and Sagittaria latifolia. Urban wetlands had a high percentage of obligate wetland species, and most closely resembled emergent wetlands in their vegetation composition. Soil pH and soil electrical conductivity were significantly higher in urban sites, but potential net N-mineralization rates were significantly lower. Urban wetland vegetation and soil characteristics are different than those in nearby natural wetlands, and our increased knowledge of these urban ecosystems will lead to more successful restoration and creation projects.

Seawater intrusion mediates species transition in low salinity, tidal marsh vegetation

In a transitioning tidal freshwater marsh (TFM) experiencing relative sea-level rise, the native vegetation community has been introduced to both an abiotic stressor (salt) and a new plant competitor (Spartina alterniflora). Within a narrow salinity range (0–3), we examined the interplay between salt stress and plant interactions by comparing growth and nutrient status of S. alterniflora grown alone and in the presence of one of three TFM species (Leersia oryzoides, Peltandra virginica, and Phragmites australis). We conducted a mesocosm study pairing S. alterniflora with a TFM plant or a conspecific and subjecting the pairs to sub-lethal levels of salinity (0, 1.5, and 3). Measured plant traits included net photosynthesis (Anet), aboveground and belowground biomass and tissue carbon (C), nitrogen (N), phosphorus (P), and their corresponding ratios. Relative to S. alterniflora grown alone, the presence of either TFM grass (L. oryzoides and P. australis): (1) altered S. alterniflora Anet, (2) suppressed S. alterniflora biomass accumulation aboveground and belowground in all salinity treatment levels, and (3) altered aboveground and belowground tissue nutrient content. Regardless of neighbor, S. alterniflora’s growth and nutrient status was greatest at the lowest salinity and remained largely unchanged in the presence of P. virginica. These results suggest that S. alterniflora can successfully expand into TFM communities. Once established, salt stress eventually may hasten the transition to a S. alterniflora-dominated marsh community. The success of S. alterniflora may allow these marshes to maintain vegetation and increase their likelihood of maintaining elevation with rising sea level.

Accumulation of Phosphorus and Arsenic in Two Perennial Grasses for Soil Remediation

Rice cutgrass (Leersia oryzoides Sw.) and tall fescue (Festuca arundinacea Schreb.) were assessed for potential for phytoremediation of arsenic (As) in a soil-based medium amended with phosphorus (P) in a greenhouse experiment. Arsenic was added at 30 mg kg−1, and P concentrations ranged from 0 to 120 mg kg−1. Plants were grown for 8 weeks. Rice cutgrass accumulated greater concentration and total amount of As in shoots or roots than fescue. Only the first increment of P fertilization increased As in shoots above that which accumulated without P fertilization. Phosphorus fertilization did not stimulate growth of either species. Most of the As remained in the roots of either species. Plant–soil accumulation ratios suggest that rice cutgrass has more potential in phytoremediation than fescue. Above a minimal amount, P fertilization did not enhance As accumulation in shoots and may not be useful in increasing the potential of either species to remediate soils.

NUTRIENT AND GROWTH RESPONSES OF LEERSIA ORYZOIDES, RICE CUTGRASS, TO VARYING DEGREES OF SOIL SATURATION AND WATER NITROGEN CONCENTRATION

Leersia oryzoides (rice cutgrass) is an obligate wetland plant common to agricultural drainage ditches. The objective of this greenhouse study was to expose plants to various flooding and aqueous nitrogen (N) concentrations and then to quantify the allocation of nutrients and biomass to plant components. Plants in the continuously flooded treatment (CF) had the highest tissue concentrations of copper (Cu), sulfur (S), zinc (Zn), potassium (K), sodium (Na), and manganese (Mn) in one or more plant components. Plants in the partially flooded treatment (PF) had the highest concentrations of magnesium (Mg) in leaves. The N input affected phosphorus (P) and S concentrations in roots. Leaf, stem, and root biomass were highest in PF plants. Rhizome biomass was the lowest in CF plants. These results indicate that L. oryzoides may significantly affect elemental concentrations in surface waters by its ability to uptake various elements and subsequent sequestration in various biomass components.

Tidal Freshwater Marsh Plant Responses to Low Level Salinity Increases

In a tidal freshwater marsh (TFM) in lower Chesapeake Bay, salt marsh cordgrass (Spartina alterniflora) recently has become established where TFM vegetation previously grew. To determine the potential contribution of saltwater intrusion to the observed species transition, we conducted a mesocosm study subjecting Spartina and two TFM perennials (Peltandra virginica and Leersia oryzoides) to sub-lethal levels of salinity (0, 2, 4 and 6). We measured plant performance as carbon dioxide flux over the leaf stomata as a proxy for net photosynthesis (Anet), aboveground and belowground biomass and tissue carbon (C), nitrogen (N) and phosphorus. For Spartina, all metrics were unchanged across the range of tested salinity. The TFM species, however, had lower Anet than Spartina and decreased with added salinity. TFM biomass was reduced up to 86 % in both the aboveground and belowground compartments, and aboveground nutrient allocation was altered: N increased in Leersia and P increased in Peltandra with increasing salinity. Under this simulation of increased salt intrusion associated with climate change and sea level rise, TFM species responded with decreased biomass and decreased tissue C:N. Although other factors must contribute, the abiotic salt stressor leads to plant responses consistent with the observed replacement of TFM species by Spartina.

Eradication and control of invasive alien plants in the Mediterranean Basin: towards better coordination to enhance existing initiatives

The European and Mediterranean Plant Protection Organization (EPPO), in the framework of its activities in the Mediterranean Basin, launched a questionnaire to gather information on eradication actions and control actions for invasive alien plants. Thirty‐four (34) eradication actions were reported, 16 occurring in Spain, 7 in Italy, 7 in France, 1 in Portugal, 1 in Malta, and 2 on the southern rim of the Mediterranean, with 1 in Israel and 1 in Tunisia. Twenty‐two (22) species were targeted, and the habitats where such actions were undertaken most frequently were coastal dunes, sandy shores and aquatic ecosystems. Most of the species that have been the object of an eradication action were known invasive species recorded in the EPPO lists, such as Ailanthus altissima, Buddleia davidii, Carpobrotus spp., Eichhornia crassipes, Ludwigia peploides, Pennisetum setaceum, Pistia stratiotes, Solanum elaeagnifolium and Sicyos angulatus. Other eradicated species have a limited distribution in the EPPO region and may represent emerging invasive plants, such as Ambrosia confertifolia, Cylindropuntia rosea, Leersia oryzoides, Leptochloa fusca subsp. uninervia and Marsilea drummondii. Control actions concerning 90 species were also reported. A large number of eradication actions, as well as management actions, are therefore happening in Mediterranean countries. At present countries appear to operate with complete autonomy, without consulting neighbouring countries or other stakeholders within the country. There is therefore a need for coordination of new eradication actions.