Scirpus Maritimus Research Articles

Diversity and Distribution of Hydrophytes and Halophytes in Khijadiya Wetland, Jamnagar, Gujarat (India)

Khijadiya is a wetland having two different types of vegetation, i.e. hydrophytes growing in/around fresh water ponds and halophytes growing in/near intertidal mud flats. A study was conducted on the diversity and community composition of hydrophytes and halophytes in Khijadiya wetland. A total of 12 hydrophytes and 10 halophytes were recorded. The freshwater area was dominated by the emergent hydrophytes like Bolboschoenus maritimus , Fimbrystylis ferruginea and Cyperus difformis whereas the saline habitat was dominated mainly by halophyte (mangrove) species like Avicennia marina . The entire wetland area was endowed with various community groups e.g. Bolboschoenus maritimus - Fimbrystylis ferruginea cyperus difformis community (a freshwater community) and Avicennia marina community (a saline water community).

Macrophytes and groundwater drive extremely high organic carbon concentration of soda pans

Abstract Endorheic soda pans are among the highest dissolved organic carbon (DOC) content aquatic systems on the planet with concentrations up to 1 g/L. Considering the importance of inland waters in the global carbon cycle, understanding the drivers of such outstanding organic carbon pools is eminent. The soda pans of the Carpathian Basin present a wide variability of biotic and abiotic characteristics that provide an adequate system to assess the determinants of extreme high DOC concentrations. Here, we demonstrate through a multi‐site comparison, a multi‐year seasonal monitoring, and a laboratory experiment that the dissolved organic matter content of the highest DOC concentration soda pans is primarily of groundwater and emergent macrophyte origin. More precisely, the multi‐site comparison of 14 soda pans revealed that variation of coloured dissolved organic matter (CDOM) content of the surface water of soda pans is partially explained by the CDOM content (22% of variation) of local groundwater, indicating the significant role of allochthonous terrestrial DOC sources. Further 23% of CDOM variation could be accounted for by Bolboschoenus maritimus species‐specific emergent macrophyte cover, while the contribution of Phragmites australis cover was only minor. In line with the results of the multi‐site comparison, our decomposition experiment demonstrated that both B. maritimus and P. australis have the potential to release substantial amount of organic matter into soda pans. However, the organic matter release of B. maritimus leads to twice as high DOC and 3.5‐times higher CDOM concentrations than P. australis. Considering previous organic matter release studies, we concluded that P. australis is a relatively low organic matter releaser emergent macrophyte, and therefore the species composition of emergent macrophytes has to be carefully considered in autochthonous plant‐derived DOM estimations. Finally, the multi‐year seasonal monitoring of two distinctive soda pans showed that the high organic matter concentrations depend not only on their intrinsic characteristics but also on interannual variability. More precisely, we demonstrated that the highest CDOM and DOC concentrations that occurred in a coloured (i.e. brown, low total suspended solids) soda pan with extensive (95%) macrophyte cover dominated by B. maritimus were measured in a period characterised by high pH and low water levels, which were presumably the consequence of increased evaporation due to decreased precipitation and above average temperature. Our results indicate that considering climate change trends common for most endorheic regions (i.e. increased temperature and modified precipitation regimes), extremely high organic matter concentrations might become more frequent in the near future in local water bodies, particularly in those highly influenced by groundwater inflow. Furthermore, soda pans with vast specific macrophyte cover and substantial groundwater inflow might become organic carbon processing hotspots.

Assessment of the habitat conditions of a rare and endangered inland saline wetland community with Bolboschoenus maritimus (L.) Palla dominance in Southeastern Europe: the effects of physical–chemical water and soil properties

Continental inland saline wetlands are among the most endangered habitats in Europe. In the Danube-Tisza-Danube canal network (Serbia, Southeastern Europe), which is one of the largest canal networks on the continent, the rare and endangered inland saline wetland Bolboschoenus maritimus community (BMC) has been found at only two locations. Two vegetation types of the community have been identified: (i) with Bolboschoenus maritimus and Marsilea quadrifolia (BMC-M) dominance and (ii) with Bolboschoenus maritimus and Butomus umbellatus (BMC-B) dominance. The aim of the study was to compare the habitats of the ascertained vegetation types in terms of 55 water and soil properties that influence their development, floristic composition and differentiation. The main properties influencing the community development and differentiation were water alkalinity, chemical oxygen demand, CO32−, water pH, soil conductivity, K+ and Ca2+ content in the soil. Both vegetation types grow in non-saline, slightly alkaline, nutrient-rich habitats with eutrophic water. When compared to BMC-B, BMC-M was found on heavy clay soils with higher conductivity, CaCO3, humus, nutrients, macroelements, and Na+ content, in shallower water with higher suspended solids and oxygen content, lower contents of nutrients, dissolved salts, HCO3−, macroelements, conductivity, and alkalinity. The study provides new data on the BMC distribution in this part of Europe and the first detailed information on its habitat conditions. Thirty-one species from the European Red List of Threatened Species were found in the stands. These results may be useful when deciding on the appropriate preservation measures aimed to rehabilitate other wetland habitats and biodiversity.

Nature-based shoreline protection by tidal marsh plants depends on trade-offs between avoidance and attenuation of hydrodynamic forces

In face of growing land-flooding and shoreline-erosion risks along coastal and estuarine shorelines, tidal marshes are increasingly proposed as part of nature-based protection strategies. While the effect of plant species traits on their capacity to attenuate waves and currents has been extensively studied, the effect of species traits on their capacity to cope with and grow under wave and current forces has received comparatively less attention. We studied the relationships between species zonation and the associated two-way interactions between species traits and hydrodynamics, by quantifying the effectiveness of avoidance and attenuation of hydrodynamic forces under field conditions. Measurements were done for two pioneer tidal marsh species in the brackish part of the Elbe estuary (Germany). Schoenoplectus tabernaemontani (S. tabernaemontani), which grows as a single stem without leaves and Bolboschoenus maritimus (B. maritimus) which grows as a triangular stem with multiple leaves. Our results reveal that S. tabernaemontani grows more seaward being exposed to stronger hydrodynamic forces than B. maritimus. The stems of S. tabernaemontani have, in comparison to B. maritimus, a lower flexural stiffness and less biomass, which decrease the experienced drag forces, thereby favoring its capacity to avoid hydrodynamic stress. At the same time, these plant traits which favor such avoidance capacity, were shown to also result in a lower capacity to attenuate waves and currents. Hence this implies that there are trade-offs between avoiding and attenuating hydrodynamic forces. Most efficient attenuation of waves and currents is thus only reached when species have the ability to grow under the prevailing hydrodynamic forces. Therefore, we argue that the two-way interaction between plants and hydrodynamics contributes to species zonation. The presence of this species zonation in turn enhances the overall efficiency of nature-based shoreline protection in pioneer tidal marshes.

СТРУКТУРА ВОДНОЇ ФЛОРИ ВОДОТОКІВ КІЛІЙСЬКОЇ ДЕЛЬТИ ДУНАЮ

Здійснено структурно-порівняльний аналіз таксономічної, екологічної та географічної структури флори водотоків Кілійської дельти Дунаю. Конспект досліджуваної флори нараховує 41 вид з 27 родів, 21 родин, 16 порядків, 4 класів та 3 відділів. Проаналізовано таксономічний склад основних таксономічних одиниць, та співвідношення між ними: відділ Magnoliophyta переважає (90.2 %), в межах якого домінує клас Liliopsida (83.8%). До перших трьох провідних родин належать Potamogetonaceae, Lemnaceae та Hydrocharitaceae, які складають 36.6% від загальної кількості флори У складі флори представлені шість видів адвентивної фракції – один археофіт (Acorus calamus L.) і п’ять кенофітів (Azolla caroliniana Willd., Azolla filiculoides Lamark., Elodea canadensis Michx., Sagittaria latifolia Willd., Vallisneria spiralis L.). Рідкісні рослини, що охороняються на території всієї України у водотоках КДД представлені трьома видами: Salvinia natans (L.) All., Nymphoides peltata (S.G.Gmel.) Kuntze та Trара natans L. s.l. До регіонально рідкісних видів, які охороняються тільки на території Одеської області належать ще п’ять видів: Lemna gibba L. (вразливий), Bolboschoenus maritimus (L.) Palla (недостатньо вивчений), Najas marina L. (недостатньо вивчений), Potamogeton gramineus L. ( недостатньо вивчений), Typha grossheimii Pobed. ( недостатньо вивчений). Екологічна структура представлена трьома екотипами, серед яких найбільше гідрофітів – 23 (56.1 %). В ньому переважає екогрупа вільно плаваючі на поверхні води (22%). Співвідношення екотипів гідрофіти, гелофіти, гігрогелофіти складає 4:2:1. В хорологічному спектрі зональних географічних груп найбільша кількість видів відноситься до плюризональної групи – 18 видів (44%). Серед регіональних груп переважає циркумполярне поширення, його мають також 18 видів (44%). За характером розміщення ареалів видів в океанічних або внутрішніх водоймах найбільша кількість видів належить індиферентній до континентальності та океанічності групі. Подібний спектр є характерним для водної флори України та для інших флор різних регіонів помірної зони Євразії.

Wave effects on seedling establishment of three pioneer marsh species: survival, morphology and biomechanics.

It is important to have an in-depth mechanistic understanding of tidal marsh establishment and dynamics to ensure the long-term persistence of these valuable ecosystems. As wave forcing may be expected to impact seedling establishment, we studied the effect of water-imposed drag forces on seedling survival, morphology and biomechanical properties of three marsh pioneer species that are dominant along the salinity gradient in many areas around the world: Spartina anglica (salt to brackish), Scirpus maritimus (brackish) and Phragmites australis (brackish to fresh). Using a newly developed plant-shaking mesocosm (PSM) that mimicked water-imposed wave drag forces, the effect of wave stress on seedling survival was examined, together with impacts on morphology and biomechanical properties. After 7 weeks of exposure to wave stress, lowered seedling survival and growth for all species was revealed. Wave treatments increased the root/shoot biomass ratio to enhance anchorage and made seedlings more flexible (i.e. reduced flexural rigidity), which might be regarded as a mixed outcome between a stress avoidance and stress tolerance strategy. The different biomechanical responses between the three dominant marsh pioneer species, overall, make them less resistant to external stress. Therefore, our results indicate that the likelihood of marshes becoming established is reduced if wave energy increases. Despite the different biomechanical response of these three pioneer species to waves, the seedlings of all species were found to have low resistance to external stresses.

Carbonate crusts of Paleolake Zhuyeze, Tengeri Desert, China: Formation mechanism and paleoenvironmental implications

Carbonate crusts with unusual morphologies are scattered on the Holocene sand surface, i.e., dunes, which cover the Paleolake Zhuyeze bed in the Tengeri Desert, China. Two types of the crusts were identified. The first type contained fossilized wrinkles of plant root cortex, while the second type consisted of hollow chambers without the wrinkle features. Optical microscopy, scanning electron microscopy and cathodoluminescence analyses were performed to investigate the mineralogy and geochemistry of the crusts. Fossilized cortex texture imprints on the first type of crusts suggested that the crusts formed around the deceased rhizomes of reeds (Phragmites communis) as the nuclei of encrustation. Weakly oxidizing soil–sediment with rhizome was a prerequisite, which was favorable for rhizome decomposition to produce sufficient CO2 and HCO3− and generate carbonate minerals of encrustation on rhizome surfaces, with lake water as the main Ca2+ supply. A conceptual formation mechanism of the encrustation was conjectured. Similar to the formation mechanism of the first type, another type of crusts with chambers and without fossilized imprints of the cortex textures formed around the spherical rhizomes of Scirpus maritimus. The crust characteristics and other evidence suggested that the lake water was fresh; water plants, such as P. communis and S. maritimus, and snails previously inhabited the water; and encrustation reflected a stable, slow-oxidizing soil–sediment environment. These desert crusts provided insights to study paleoecology, paleohydrology and water-soil/sediment interface environment in the paleolake.

Biota from the coastal wetlands of Praia da Vitória (Terceira, Azores, Portugal): Part 4 – Vascular plants

BackgroundThe data presented here come from field observations, carried out between 2014 and 2017, as part of a LIFE research project aiming to preserve and restore three coastal wetlands of Praia da Vitória (Terceira Island, Azores, Portugal) (LIFE-CWR). A total of 23 vascular plant species surveys were carried out in three sites: one for each semester in Paul da Praia da Vitória (PPV) and Paul da Pedreira do Cabo da Praia (PPCP); one for each semester (except in 2014) in Paul do Belo Jardim (PBJ). The main objectives were to determine the plant richness of the three sites and to monitor yearly variation on species composition.New informationA total of 107 taxa, belonging to 50 families, were observed, many of which are new records for the area, especially in PBJ and PPCP, where 78 and 92% of species records were new. A few very rare species in the Azores were recorded in these coastal wetlands, namely Lotus creticus, Bolboschoenus maritimus, Juncus maritimus and Polygonum maritimum.

Trends in the Recent Evolution of Coastal Lagoons and Lakes in Galicia (NW Iberian Peninsula)

Coastal lagoons are habitats of great environmental value. However, they are currently subject to major threats, particularly due to increasing sea levels. This study aims to identify changes—both natural and induced by anthropic activity—and their impact on the recent evolution of three different types of coastal lagoons in Galicia (Louro, Vixán, and Xuño). The application of information obtained through laser imaging detection and ranging (LiDAR) techniques suggests that the outer limits of the three lagoon systems have not experienced any relevant changes in the last 60 years (i.e., no occupation of the lagoon area has been identified). However, the internal configuration of these wetland areas has experienced some alterations. A generalized increase in the area occupied by macrophytic communities (Phragmites australis, Scirpus maritimus, Juncus maritimus, etc.) has been observed. Image interpretation by geographic information systems (GIS) and field surveys suggest that the area currently occupied by macrophytes experienced a 7% to 63% increase at the expense of the free water body. This loss of flooded area is consistent with the increase in sedimentation rates associated with the convergence of several causes, such as the abandonment of traditional macrophyte biomass harvesting and agricultural activities around the lagoons, the expansion of riparian forests, and sediment contributions by erosion due to recurrent forest fires within the drainage basins of each lagoon. Finally, water and sediment composition suggest that, of the three studied lagoons, two of them (Louro and Vixán) are included within the definition of “coastal lagoons” (habitat code 1150) by the Habitats Directive (Directive 92/43/EEC), while the Xuño lagoon should be considered a “natural eutrophic lake” (habitat code 3150).

Vegetation patterns in a South American coastal wetland using high-resolution imagery

ABSTRACT The aim of this study was to identify and characterize the main plant communities in a temperate coastal wetland using high-resolution imagery. We produced a map of Samborombón Bay at 1:25,000 scale using a WorldView-2 image. An Object-based Image Analysis approach was chosen, and an unsupervised classification algorithm was applied. Overall classification accuracy was 81%, and the Kappa index was 78.1%. Six land cover types were mapped including four main natural monospecific plant communities. The lower intertidal area was dominated by mudflats without vegetation and stands of Bolboschoenus maritimus. The middle intertidal area was dominated by Sarcocornia ambigua, while, in the higher intertidal area, Sporobolus densiflorus and grasslands with Cortaderia selloana prevailed. We found four spatial patterns at a landscape scale, based on the presence and spatial distribution of the natural plant communities. This map represents a valuable tool for future studies on wetland environmental indicators.

Sediment Dynamics of Natural and Restored Bolboschoenus maritimus Saltmarsh

Saltmarshes are biogeomorphic ecosystems comprising halophytic plant communities typically located on low energy temperate coasts. Their distribution and structure are controlled by several key drivers, including sediment supply, type of vegetation, elevation and local hydrodynamics. These dynamic systems are highly vulnerable and estimated to be experiencing annual losses of 1-2% globally. Past restoration efforts have largely implemented managed realignment strategies, however, examples of, and research on, conservation initiatives employing direct transplantation of saltmarsh vegetation into damaged or receding saltmarsh stands is less common. Here an example of transplantation restoration was investigated to understand its influence on sediment dynamics. Sediment settlement, deposition and accretion rates of natural and restored vegetation (Bolboschoenus maritimus) and adjacent bare mudflats in a small estuary system were studied across consecutive seasons from summer 2015 to spring 2016 to examine the success of transplantation. Natural areas of B. maritimus were shown to be most effective at retaining deposited material, although experiencing the least amount of deposition (an average of 48 g/m2 per day), accreting by nearly 7.5 mm over the experimental period. Mudflat areas experienced the most deposition (an average of 322 g/m2 per day) whilst exhibiting the greatest erosion over the study, a decrease in level of 6 mm. Restored areas experience similar rates of deposition as their natural counterparts, however, did not retain this material as efficiently, presenting an erosion of 1.6 mm. The study indicates certain biogeomorphic processes have been altered within the restored area and beginning to reflect those of the natural area. However, the restored vegetation does not yet fully match the functionality of the natural B. maritimus stand, specifically where the natural stand displayed a net accretion of material the restored area did not. Such discrepancies may impact on the continued survival of the restoration site, which may have implications for the potential of transplanting to deliver ecosystem services, such as climate change mitigation through carbon burial.

Loss of spatial structure after temporary herbivore absence in a high‐productivity reed marsh

Abstract Grazing can significantly impact spatial heterogeneity and conservation value of ecosystems. Earlier work revealed that overgrazing may stimulate persistent vegetation collapse in low‐productivity environments where vegetation survives by concentrating scarce resources within its local environment. However, it remains unclear whether grazer fluctuations may cause persistent vegetation changes in high‐productivity systems where dense stands facilitate their own survival by hampering grazer access. Here, we experimentally tested how the release from grazing by greylag geese (Anser anser) affects spatial vegetation structure in a highly productive, brackish marsh in which dense reed (Phragmites australis) stands and bare roosting areas coexist. Next, we assessed the resilience of the change in vegetation patterning by reintroducing the geese after a 2‐year exclosure period. During herbivore exclusion, vegetation rapidly colonized the bare areas, while reintroduction of herbivores generated a clear species‐specific response. Specifically, the pioneer species, Bolboschoenus maritimus, was immediately eradicated, while the dense and high structure of P. australis facilitated its own persistence by limiting grazer access. Surface accretion (~1 cm/year) during herbivore exclusion further amplified this herbivore‐inhibiting feedback, because greylag geese primarily rely on waterlogged conditions for grubbing. Synthesis and applications. Our results indicate that temporary reductions in herbivore numbers may induce persistent unfavourable changes in the spatial structure of a high‐productivity system. It is therefore important to first assess whether vegetation changes are naturally reversible or persistent. If state shifts are indeed persistent, sufficiently high grazer densities must be maintained to warrant the favourable heterogeneous system. If changes in vegetation structure negatively impact grazer densities, active management such as sod cutting or mowing may be required to restore ecosystem structure and functions.

Biomechanical properties of marsh vegetation in space and time: effects of salinity, inundation and seasonality.

Over the last decade, the importance of plant biomechanical properties in shaping wave dissipation efficiency of marsh vegetation has gained growing attention. Here we provide the first analyses of how biomechanical stem properties vary with seasons and along environmental gradients in coastal and estuarine marshes, which is essential to enable accurate assessments of flood defence value of marsh vegetation. We quantified both spatial and seasonal variation in stem flexibility and breakability for a variety of common marsh vegetation (Spartina anglica, Scirpus maritimus, Phragmites australis, Elymus athericus, Suaeda maritima, Aster tripolium, Saliconia procumbens) distributed along both salinity and inundation gradients. Increasing salinity tends to induce a shift from species with tall shoots, high flexural stiffness (stem resistance to bending; N mm2) towards species with shorter and more flexible stems. The same trend was found with increasing inundation stress (i.e. decreasing elevation) from the higher part of the low marsh towards the pioneer zone. Stem breakability (the force required to break or fold a stem, N) followed the same pattern of stem stiffness due to the positive relationship between flexural strength (material resistance to flexure, N mm-2) and Young's bending modulus (material resistance to bending; N mm-2). Shifts in stem stiffness and breakability at the community level were found to relate positively to the variation in canopy height between species, highlighting the concurrence of changes in morphological and biomechanical traits under environmental changes. Compared to the differences between species, within-species variability between sampling locations and between seasons is generally minor. Our findings imply that environmental changes may significantly modify wave attenuation capacity of coastal vegetation by inducing species shifts. This emphasizes the need to understand the response of community composition to climate change and human disturbances, when using nature-based flood protection by coastal vegetation as an adaptive response to global change.

How effective are tidal marshes as nature‐based shoreline protection throughout seasons?

AbstractNature‐based mitigation is increasingly proposed as a strategy to cope with global change and related risks for coastal flooding and erosion. Tidal marshes are known to provide shoreline protection as their aboveground biomass attenuates waves and their belowground biomass contributes to reducing erosion rates. The aim of this study was to quantify how effectively wave attenuation rates and erosion reduction rates are sustained throughout seasons in pioneer tidal marshes in the Elbe estuary (Germany). Changes in hydrodynamics and sediment dynamics were measured during 17 months along three sea‐to‐land transects of 50 m length. Simultaneously, changes in biomass of the monospecific pioneer vegetation (Bolboschoenus maritimus) were measured monthly. This study shows that wave and flow attenuation rates positively correlate with seasonal variations in aboveground biomass, that is: in summer, aboveground biomass and associated wave and flow attenuation rates are highest; while aboveground biomass is washed away during the first storms in autumn or winter, resulting in low wave and flow attenuation rates. Contrastingly, maximum incoming wave heights and flow velocities occur during winter, indicating that wave and flow attenuation is most needed then. However, hibernating root biomass assures low erosion rates in winter, especially at sandy sites. Although wave attenuation by pioneer marshes is highly variable throughout seasons and pioneer marshes alone are not so effective, they might facilitate the survival of higher marshes. Therefore, it is important to conserve or restore a gradual sea‐to‐land gradient from tidal flats, over pioneer marsh to high marsh to provide nature‐based shoreline protection.

Anaerobacillus alkaliphilus sp. nov., a novel alkaliphilic and moderately halophilic bacterium.

Two alkaliphilic and moderately halophilic bacterial strains B16-10T and Z23-18 characterized by optimal growth at pH 9.0-10.0 and 5 % (w/v) NaCl, were isolated from the rhizosphere soil of the bayonet grass (Bolboschoenus maritimus) in the Kiskunság National Park, Hungary. Cells of both strains stained Gram-positive, were motile straight rods, and formed terminal, ellipsoidal endospores with swollen sporangia. The isolates were facultative anaerobic, catalase positive, oxidase negative. Both strains contained meso-diaminopimelic acid as diagnostic diaminoacid of the peptidoglycan. Menaquinone-7 (MK-7) was the predominant isoprenoid quinone. Anteiso-C15 : 0, C16 : 1ω11c and iso-C14 : 0 were the major cellular fatty acids. The DNA G+C content of both strains was 35.8 mol%. The 16S rRNA gene based phylogenetic analysis revealed that the facultative anaerobic strains B16-10T and Z23-18 showed the highest similarities to the type strains of anaerobic Anaerobacillus isosaccharinicus NB2006T (98.7 and 99.1 %), A. macyae JMM-4T (98.2 and 98.4 %), A. alkalidiazotrophicus MS 6T (97.7 and 98.4 %), A. alkalilacustris Z-0521T (97.5 and 98.3 %) and A. arseniciselenatis DSM 15340T (97.5 and 98.2 %). However, the distinctive phenotypic and genetic results of this study confirmed that strains B16-10T and Z23-18 represent a novel species, for which the name Anaerobacillus alkaliphilus sp. nov. is proposed. The type strain is B16-10T (=DSM 29790T=NCAIM B 02608T).

Sensitivity of Annual Weeds Against Metolachlor + Bensulfuron - Methyl Herbicide in Transplanted Rice


 Field trials were conducted at Bangladesh Rice Research Institute (BRRI), Gazipur during aman, 2014 and boro, 2014-15 to evaluate the efficacy of metolachlor + bensulfuron methyl 20% WP on weed suppression of transplanted rice. Metolachlor + bensulfuron methyl 20% WP @ 150, 190 and 230 g ha-1 were applied and pyrazosulfuran ethyl @ 125 g ha-1, weed free and unweeded control were the treatment variables. Visual observations indicated that this herbicide possesses high selectivity and not toxic to rice plants. The results revealed that the major weed flora associated with the transplanted rice was mainly comprised of two grasses, two sedges and three broadleaf in aman and two grasses, two sedges and two broadleaf in boro season. The most dominant weeds were Cyperus difformis, Echinochloa crus-galli, Scirpus maritimus and Monochoria vaginalis in both the growing seasons. Application of metolachlor + bensulfuron methyl 20% WP @ 190 g ha-1 was most effective to suppress weeds in both the seasons resulting in increased grain yield more than 40% as compared to unweeded control. Therefore, metolachlor + bensulfuron methyl 20% WP@ 190 g ha-1applied at one to two leaf stage of weed effectively controls the weed infestation in transplanted rice.
 Bangladesh Agron. J. 2018, 21(1): 61-70
 

Effects of a Surfactant Seed Coating on Alkali Bulrush Germination and Biomass

Great Salt Lake (GSL) wetlands provide vital ecosystem services, including habitat for migratory birds. Alkali bulrush (Bolboschoenus maritimus) plays an important role in providing these services, but invasion by Phragmites australis has reduced the extent of alkali bulrush stands in GSL wetlands. Restoring alkali bulrush is a primary goal for GSL managers following Phragmites removal. However, rising temperatures and changing precipitation patterns with climate change, as well increasing human water demands upstream, may alter the hydropattern of GSL wetlands, thus lowering soil moisture availability and potentially inhibiting alkali bulrush germination and seedling establishment. Surfactant seed coatings have been effective in aiding the germination of seeds in upland restoration sites by reducing soil water repellency, but have not been tested in wetlands. We tested whether the addition of a surfactant seed coating to alkali bulrush seeds improved germination at four water levels in a greenhouse. Water level and seed coating were significantly associated with improved germination. In a second experiment, we tested the effect of the seed coating at a low and high dose and staggered water level drawdowns on seedling height and biomass over six weeks. Seed coating and time of water level drop were not significantly associated with differences in seedling height. The water level decrease may not have been extreme enough to negatively affect seedlings. More research is needed to determine if a surfactant seed coating enhances alkali bulrush germination and growth under less favorable water availability conditions.

Stable isotopes in helophytes reflect anthropogenic nitrogen pollution in entry streams at the Doñana World Heritage Site

Nitrogen (N) loading from anthropogenic activities is contributing to the eutrophication and degradation of wetlands worldwide. Doñana (southwestern Spain), includes a dynamic marshland protected as a UNESCO World Heritage Site, which has a catchment area exposed to increasing N inputs from intensive agriculture and poorly treated urban wastewaters. Identifying the sources of N entering this iconic wetland complex is vital for its conservation. To this end, we combined multiyear (2014–2016), spatially-explicit data on N concentration in water samples with measurements on the relative abundance of N stable isotopes (δ15N) in Bolboschoenus maritimus and Typha domingensis, two dominant helophytes (i.e. emergent macrophytes) in the Doñana marsh and entry streams. Overall, plant tissues from entry streams showed higher δ15N values than those from the marsh, particularly in those streams most affected by urban wastewaters. Isotopic values did not differ between plant species. Water samples affected by isotopically-enriched urban wastewaters and other diffuse organic N inputs (e.g. livestock farming) had relatively high Dissolved Inorganic Nitrogen (DIN) concentrations. In contrast, in streams mainly affected by diffuse N pollution from greenhouse crops, high DIN values were related to isotopically-depleted N sources (e.g., inorganic fertilizers). Thus, helophytes, in combination with other parameters such as N concentration in water or land cover, can be valuable indicators of anthropogenic pressures in Mediterranean wetlands. Helophytes have widespread distributions, and can be readily sampled even when water is no longer present. However, identification of specific N sources through helophyte δ15N values is limited when key potential N sources are isotopically undistinguishable (e.g. fertilizers vs. atmospheric sources).

Fine‐scale genetic diversity and landscape‐scale genetic structuring in three foundational bulrush species: implications for wetland revegetation

The appropriate sourcing of seeds for restoration is critical for establishing foundational plant species that support ecosystem functions and services. Genetic analyses of such species can yield insights into patterns of genetic diversity and structuring to inform seed collections. Here we document, for three foundational bulrush species, distinct genetic patterns to guide restoration of wetlands along the iconic Great Salt Lake, the largest lake in western North America. Specifically, Schoenoplectus acutus and Schoenoplectus americanus had moderate levels of site‐scale genet richness and relatively low genet richness levels within 1‐m2 plots. These patterns contrast with Bolboschoenus maritimus, which had higher levels of site‐ and plot‐level genet richness, and has therefore likely experienced more recent seedling establishment. At the landscape scale, we found some evidence for genetic isolation of individuals at more remote sites (namely Fish Springs National Wildlife Refuge in the West Desert of Utah), but all species are relatively well dispersed over hundreds of kilometers, a pattern most likely to occur via avian dispersal. In our mechanistic dispersal assessment, we found abundant bulrush seeds present in waterfowl gizzards and those seeds germinated readily despite (or because of) partial digestion. Migratory waterfowl likely facilitate the broad dispersal of all species and may aid in bulrush establishment by breaking seed dormancy. These findings suggest that seeds for restoration should be collected within and among seed source sites to ensure a diverse restoration seed lot that does not disrupt gene flow patterns.

Sensitivity of Annual Weeds against Sulfentrazone 48 SC herbicide in Rice Cultivation

Herbicides are used successfully for weed control in rice fields for rapid effect, easier to application and low cost involvement in comparison to the traditional methods of hand weeding. Sulfentrazoneis a new pre-planting herbicide in Bangladesh. Field trials were conducted at Bangladesh Rice Research Institute (BRRI), Gazipur during Aman 2014 and Boro 2014-15 to evaluate the efficacy of sulfentrazone 48 SC on weed suppression and performance of transplanted rice. Treatments were Sulfentrazone 48 SC @ 150, 200 and 250 ml ha-1, pretilachlor 500 EC @ 1000 ml ha-1, weed free and unweeded control. Visual assessment indicated that this herbicide possesses high selectivity and not toxic to rice plants. The results revealed that the major weed flora associated with the transplanted rice was mainly comprised of two grasses, two sedges and four broadleaves in Aman 2014 and two grasses, two sedge and two broadleaves in Boro 2014-15. The most dominant weeds were Cyperus difformis, Echinochloa crus-galli, Scirpus maritimus and Monochoria vaginalis in both the growing seasons. Application of Sulfentrazone 48 SC @ 200 ml ha-1 was most effective to suppress weed density and dry masses in both the seasons resulting increased grain yield more than 50% as compared to unweeded control. Therefore, Sulfentrazone 48 SC @ 200 ml ha-1 should apply two or three days before plantingfor effectively control weeds in riceBangladesh Rice j. 2017, 21(1): 67-76