Australis Biomass Research Articles

Unraveling the synergistic promotion mechanism of Fe0 coupling phragmites australis biomass for nitrogen removal in coastal wetland: From low to moderate salinities

The simulated coastal constructed wetlands supplemented with Fe0 and phragmites australis (P.A) biomass (CW-M) were constructed to improve nitrogen removal under different salinities (0–15‰). Results showed that the denitrification performance of CW-M were improved significantly, with the higher NO3−-N removal of 72–94% and lower N2O emission flux, when compared with mono-P.A biomass(CW-bio), mono-Fe0 system (CW-Fe) and control system. The nitrogen removal showed a trend of first increasing (0‰–7‰) and then decreasing (7‰–15‰) with the highest NO3−-N removal of 94% and enhanced removal efficiency of 41%in CW-M. Fe0 and P.A biomass coupling could reduce the stress of salinity on denitrification. Batch experiments have demonstrated that Fe0 and P.A biomass could mutually stimulate more total organic carbon and total iron (TFe) release as electron donors for denitrification. Meanwhile, appropriate salinity could also promote the release of TFe. The typical heterotrophic denitrifying genera Bacillus and iron autotrophic denitrifying genera Thermomonas have the highest proportion in CW-M, with 21.83% and 0.10%, respectively. Fe0 and P.A biomass adding simultaneously promoted the carbon and iron metabolism, further enhancing the nitrogen metabolism process. The joint enhancement of autotrophic and heterotrophic denitrification contributes to NO3−-N removal in CW-M for treating saline, low C/N wastewater in coastal wetlands.

Biofuel production from macrophytes

The depletion of natural resources and minerals is leading to slower economic growth in many countries. Sustainable economic development requires rational resource management and waste reduction, as disposal or incineration pollutes fertile soils, the atmosphere, and water bodies. This study aimed to develop methods for obtaining the technology of liquid biofuel (bio-oil) production by hydrothermal revitalization of the biomass of macroalgae and aquatic macrophytes. The thermal properties and caloric content of aquatic plant biomass, specifically Phragmites australis, Scirpus lacustris, Typha angustifolia L., and Sparganium erectum L., were investigated, and the optimal parameters for hydrothermal revitalization of their biomass were identified. The biomass of P. australis and S. lacustris was shown to have optimal thermal properties, having an ash content of 7.6% and 6.6%, respectively, and a maximum mass loss temperature of 351 °C and 345 °C, respectively. The production regimes for liquid biofuel (bio-oil) were established. The properties of fuel derived from P. australis biomass were evaluated, including the content of easily boiling fractions and coke residue. The magnitude of fuel yield from biomass P. australis was found to be correlated with the quality of bio-oil. Thus, obtaining biofuels from aquatic plants is one of the promising areas of plant biomass processing.

Water conditions and arbuscular mycorrhizal symbiosis affect the phytoremediation of petroleum-contaminated soil by Phragmites australis

Phytoremediation of petroleum-contaminated soils using the synergistic functions of plants and rhizosphere microorganisms is a promising technology. However, successfully applying this approach presents challenges under certain conditions (submerged environments). This study analyzed the potential role of Phragmites australis in symbiosis with arbuscular mycorrhizal (AM) fungi during petroleum remediation at two water levels. AM inoculation promoted P. australis aboveground growth under non-flooded conditions, whereas flooding significantly increased P. australis biomass. The highest total petroleum hydrocarbon (TPH) degradation efficiency was observed in non-flooded soils, whereas submergence severely inhibited TPHs dissipation. Plants with AM inoculation treatments substantially enhanced the removal of TPHs under flooded conditions. TPH removal was positively correlated with dehydrogenase activity but negatively correlated with easily extracted glomalin-related soil proteins. Moreover, different petroleum-hydrocarbon-decaying candidates contributed to TPH removal in these two cultured soils. These findings provide valuable information for the remediation of future TPH-contaminated soils, especially applied in intermittently submerged environments.

Resource availability and parasitism intensity influence the response of soybean to the parasitic plant Cuscuta australis.

Parasitic plants can damage crop plants and consequently cause yield losses and thus threaten food security. Resource availability (e.g., phosphorus, water) has an important role in the response of crop plants to biotic attacks. However, how the growth of crop plants under parasitism are affected by environmental resource fluctuation is poorly understood. We conducted a pot experiment to test the effects of the intensity of Cuscuta australis parasitism and the availability of water and phosphorus (P) on soybean shoot and root biomass. We found that low-intensity parasitism caused ~6% biomass reduction, while high-intensity parasitism caused ~26% biomass reduction in soybean. Under 5-15% water holding capacity (WHC), the deleterious effect of parasitism on soybean hosts was ~60% and ~115% higher than that under 45-55% WHC and 85-95% WHC, respectively. When the P supply was 0 μM, the deleterious effect of parasitism on soybean was 67% lower than that when the P supply was 20 μM. Besides, the biomass of C. australis was highest when both the water and the P availability were lowest. Cuscuta australis caused the highest damage to soybean hosts under 5 μM P supply, 5-15% WHC, and high-intensity parasitism. Additionally, C. australis biomass was significantly and negatively related to the deleterious effect of parasitism on soybean hosts and to the total biomass of soybean hosts under high-intensity parasitism, but not under low-intensity parasitism. Although high resource availability can promote soybean growth, the two resources have different impacts on the response of hosts to parasitism. Higher P availability decreased host tolerance to parasites, while higher water availability increased host tolerance. These results indicate that crop management, specifically water and phosphorus supply, can efficiently control C. australis in soybean. To our best knowledge, this appears to be the first study to test the interactive effect of different resources on the growth and response of host plants under parasitism.

Potential of Marine Seaweeds for Bioactive Compounds: a Comprehensive Analysis of Padina australis Biomass

Potential of Marine Seaweeds for Bioactive Compounds: a Comprehensive Analysis of Padina australis Biomass

Effect of Two-Step Formosolv Fractionation on the Structural Properties and Antioxidant Activity of Lignin.

The formosolv fractionation process has been demonstrated to be an effective approach toward lignin recovery as an antioxidant from lignocellulosic biomass. In this study, four lignin fractions, FL-88%, FSL-70%, FIL-70% and FL-EtAc, were isolated from Phragmites australis biomass through two-step formosolv fractionation (88% formic acid delignification followed by 70% aqueous formic acid fractionation). To better understand the structural properties of the lignin obtained from this fractionation process, four isolated lignins were successfully characterized by gel permeation chromatography (GPC), Fourier transform infrared (FT-IR), two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC NMR) spectroscopy, thermogravimetric analysis (TGA) and gas chromatograph-mass spectroscopy (GC/MS). It was found that lignin depolymerization via β-O-4 cleavage occurred via a formylation, elimination and hydrolysis mechanism, accompanied by a competitive condensation reaction. Noteworthily, two-step formosolv fractionation can produce specific lignin fractions with different ABTS and DPPH radical scavenging activities. The FL-EtAc fraction with low molecular weight (Mw = 2748 Da) and good homogeneity (PDI = 1.5) showed excellent antioxidant activity, compared with the other three isolated lignin fractions, even equal to that of commercial antioxidant BHT at the same concentration of 2.0 mg·mL−1. These findings are of great help for specific lignin from biomass as a natural antioxidant in the future.

Association of early stage fishes with surf diatom Anaulus australis accumulations in a warm temperate surf zone, South Africa

Surf zones are recognised as important nursery habitats for early stage fishes worldwide, but microhabitat opportunities for feeding and refuge are not well studied. Surf diatoms accumulate in high densities, discolouring the water and offering potential refuge and feeding opportunities. The aim of this study was to investigate the association of early stage fishes with surf diatom Anaulus australis accumulations in the Sundays Beach surf zone on the South African southeast coast. Early stage fishes were sampled within and outside of visible A. australis accumulations using a 4.5 × 1.5 m larval fish seine net with 500 μm mesh. Over 22 sampling trips, 338 replicate samples were collected. Species diversity, the overall catch per unit effort (CPUE) and that of the dominant species Chelon richardsonii, Diplodus capensis, Rhabdosargus globiceps and R. holubi, were significantly higher within accumulations compared to outside. Postflexion larvae and early juveniles occurred in significantly higher numbers within accumulations, indicating that fishes were actively selecting A. australis accumulations. Generalized linear models revealed that temperature, dissolved oxygen (mg l−1), turbidity and A. australis biomass (μg Chl a l−1) were the most significant variables correlated with the overall CPUE and that of dominant species. Since A. australis accumulations have a patchy distribution in the surf zone, it is suggested that early stage fishes are opportunistically using this resource when and where it occurs as both a feeding and refuge area. Understanding the role of microhabitats for early stage fishes is essential for understanding survival and life history strategies within the mosaic of coastal nursery areas.

NUTRITIVE VALUE OF RIPARIAN COMMON REED BIOMASS FOR RUMINANTS

The extensive reedbeds, especially Phragmites australis, that spread around then perimeter of the lake Mikri Prespa, a Ramsar protected lake in the northwest of Greece, serves beneficially for several human activities and wildlife needs. Nevertheless, the apparent overgrowth and removal of this vegetation is often problematic and imposes difficulties in management and increases costs. Recent research is focusing into the use of P. australis as an alternative or complementary feed for ruminants. The aim of the present study was to evaluate the nutritive value of P. australis biomass derived from the riparian vegetation as a potential animal feed. Biomass samples were collected from six different sites of the Mikri Prespa lake in two different time periods (i.e. early August and late October 2020). The samples were analyzed for macro- and trace elements, total protein, NDF, fat and nitrogen-free extracts. Location and sampling date had a significant effect on all macronutrient concentrations with significant reductions in the second sampling period. For the trace elements zinc, copper and boron higher concentrations were observed in August, while the concentration of iron increased significantly in October. Dry matter and NDF content of P. australis was particularly high, 67.08% and 46.3% respectively; while protein content was rather moderate (8.38%, August sampling) to low (5.06%, October sampling). The results show that the nutritive value of P. australis is comparable to feeds widely used in ruminant nutrition such as wheat straw or marc, indicating a potential use as an alternative or complementary coarse feed with appropriate administration or treatment.

Composition and diversity of macroalgae community in the coast of Karang Bolong, Nusakambangan Island

Karang Bolong Beach is a beach located at the eastern tip of the island of Nusakambangan Cilacap. Karang Bolong Beach has a substrate type in the coral and composite substrate (fragment coral, rock, and sand). Therefore, a lot of seaweed grows there. This research aims to determine the macroalgae community on different substrates at Karang Bolong Beach, Cilacap. This is done to explore and use seaweed as a source of bioethanol. The research method used was a survey method - sampling using transects with a random process. The research variables included the macroalgae community in terms of species diversity and abundance on different substrates. The main parameters observed were the number of species and the number of individuals for each species. Supporting parameters consist of current velocity, nitrate content, turbidity, depth, tides, salinity, temperature, and pH. The data obtained were analyzed using Primer-7 to determine the diversity and density of each macroalgae species. The results showed 11 species of macroalgae consisting of Amnasia glomerata, Caulerpa mexiana, Chaetomorpha crasa, Dictyota ciliolata, Eucheuma serna, Gracilaria arcuata. Gracilaria gigas, Laurencia subopposita, Padina australis, Rhodymenia sp., and Ulva rigida. On the coral substrate, there were eight species, and on the composite substrate, six species. Four of these species are found in both substrate types. The diversity of species on the coral substrate varies from low to moderate. The highest abundance on composite substrates dominated by Padina australis biomass with a weight of 431 g.m−2. On coral substrate dominated by Gracilaria gigas with a value of 275.33 g.m−2. The community is in an unstable condition due to ecological pressures.

Closing the loop in a constructed wetland for the improvement of metal removal: the use of Phragmites australis biomass harvested from the system as biosorbent

Among the numerous clean-up techniques for water treatment, sorption methods are widely used for the removal of trace metals. Phragmites australis is a macrophyte commonly used in constructed wetlands for water purification, and in the last decades, its use as biosorbent has attracted increasing attention. In view of a circularly economy approach, this study investigated improvement of trace metal removal by recycling the biomass of P. australis colonizing a constructed wetland, which operates as post-treatment of effluent wastewater from an activated sludge plant serving the textile industrial district of Prato (Italy). After the annual mowing of the reed plants, the biomass was dried and blended to derive a sustainable and eco-friendly biosorbent and its sorption capacity for Fe, Cu, and Zn was investigated comparing the batch system with the easier-to-handle column technique. The possibility of regeneration and reuse of the biosorbent was also evaluated. The biomaterial showed an interesting sorption capacity for Cu, Fe, and Zn, both in batch and in column experiments, especially for Fe ions. The immobilization of the biosorbent in column filters induced some improvement in the removal efficiency, and, in addition, this operation mode has the advantage of being much more suitable for practical applications than the batch process.

Mechanisms of Plant-Correlation Phytoremediation of Al-Daura Iraqi Refinery Wastewater Using Wetland Plant from Tigris River

In developing countries, conventional physico-chemical methods are commonly used for removing contaminants. These methods are not efficient and very costly. However, new in site strategy with high treatment efficiency and low operation cost named constructed wetland (CW) has been set. In this study, Phragmites australis was used with free surface batch system to estimate its ability to remediate total petroleum hydrocarbons (TPH) and chemical oxygen demand (COD) from Al-Daura refinery wastewater. The system operated in semi-batch, thus, new wastewater was weekly added to the plant for 42 days. The results showed high removal percentages (98%) of TPH and (62.3%) for COD. Additionally, Phragmites australis biomass increased significantly during experiment period with 60% increasing in wet weight. These results proved the ability of Phragmites australis to tolerance in contaminant environment and enhanced biodegradation of TPH. Two kinetic models were used, and pseudo-second order was fitted to data with R2 of 0.999.

Differences in biomass and silica content in typical plant communities with ecotones in the Min River estuary of southeast China.

Silica (Si) is a basic nutrient requirement for many aquatic organisms and its biogeochemical cycle plays an important role in estuarine coastal ecosystems. However, little is known about the role Si plays during plant–plant interactive processes in the marsh ecosystems. Here, variations in biomass, biogenic silica (BSi) content, and available Si content of Cyperus malaccensis-dominated marshes, Phragmites australis-dominated marshes, and their ecotonal marshes were studied in the Shanyutan marsh in the Min River estuary, China. Results showed that C. malaccensis and P. australis biomass in ecotones was lower than those in typical communities by 46.4% and 46.3%, respectively. BSi content in aboveground organs of C. malaccensis and culms and roots of P. australis was lower in ecotones than in typical communities, whereas BSi content in other organs showed the opposite trend. Biomass allocation in C. malaccensis and P. australis roots in ecotones was higher by 56.9% and 19.5%, respectively, and BSi stock in C. malaccensis and P. australis roots was higher than that in typical communities by 120.9% and 18.9%, respectively. Available Si content in ecotonal marsh soils was 12.6% greater than that in typical communities. Thus, the two plant species may use different strategies for Si accumulation and allocation in ecotones to adapt to the competitive environment. P. australis may expand primarily via occupation of wider aboveground space, thereby increasing the Si accumulation capacity in aboveground organs. Meanwhile, C. malaccensis may increase the Si allocation capacity of its roots to withstand the pressure from P. australis. This study will provide new insights into marsh plant competition from the perspective of Si, which can also benefit plant management in marsh ecosystems.

The fate of selected heavy metals and arsenic in a constructed wetland

The fate of Cd, Pb, Cu, Zn, Ni, Cr, and As in a horizontal subsurface flow-constructed wetland was studied. The concentrations of the risk elements in treated municipal wastewater, wetland sediments, and Phragmites australis biomass were determined. Most of the studied elements were removed from the wastewater with fair efficiencies. On the other hand, As was released to treated water in the wetland bed. The removal efficiencies obtained for the individual elements were as follows: 64.2, 48.7, 70.0, 93.9, 63.6, 63.8, and –236.2%, respectively. The concentrations measured in sediments were the highest for samples taken 1 m from the inflow zone. They were 4.11, 2.01, 6.01, 4.85, 3.39, 9.30, and 3.17 times higher as compared to the samples taken in the distance of 10 m. The pollutants were preferentially deposited at the front part of the wetland bed where anaerobic conditions predominated and sulfate reduction took place. There were no significant differences in the concentrations of the studied elements in the aboveground biomass (Phragmites australis) samples taken in the distances of 1, 5, and 10 m from the inflow zone. However, the concentrations measured in the belowground biomass samples were significantly higher for samples taken at the front part of the wetland bed. The individual element concentration ratios between the below- and aboveground biomass measured for samples taken 1 m from the inflow zone were 4.97, 5.97, 2.21, 1.58, 2.26, 5.70, and 2.66 for Cd, Pb, Cu, Zn, Ni, Cr, and As, respectively.

Plant manipulations and diel cycle measurements test drivers of carbon dioxide and methane fluxes in a Phragmites australis-invaded coastal marsh

Invasion of coastal marshes by Phragmites australis may alter carbon cycling, including fluxes of the greenhouse gases (GHGs) carbon dioxide (CO2) and methane (CH4). Understanding patterns and drivers of these GHG fluxes in P. australis-invaded coastal marshes is critical to predicting how this widespread biological invasion may impact carbon (C) sequestration in coastal marshes. The objectives of this study were (1) to test effects of P. australis aboveground vegetation removal on GHG fluxes over short timescales (up to 4 months) and (2) to contrast diel patterns of GHG fluxes in P. australis-vegetated and cleared plots. First, effects of mechanical aboveground P. australis biomass removal on GHG fluxes and soil variables were tested over a series of short-term durations (frommin to months). Next, on 3 dates, GHG fluxes were measured every 3h over complete diel cycles. Net daytime CO2 uptake (−60 to −100mmolm−2s−1) was observed where P. australis was left intact. All durations of vegetation removal produced similar CO2 emissions to those measured from intact P. australis plots during evening hours. CH4 fluxes did not differ where P. australis was removed or left intact. Greater daytime CH4 emissions (75–100μmolm−2h−1) were found than at night (20–40μmolm−2h−1) from both cleared and vegetated plots. Results of this study suggest that CO2 fluxes in this system vary primarily due to substantial photosynthetic uptake by P. australis, and that CH4 emissions are likely driven by abiotic factors, such as temperature, that vary on diel cycles. Calculation of net GHG fluxes in this P. australis-invaded coastal marsh indicates that it is a GHG sink during the growing season.

Cattle Grazing Effects on Phragmites australis in Nebraska

Phragmites australis (common reed) is one of the most widely distributed flowering plants in North America. The introduced lineage occurs in wetland and riparian areas covering a range of climatic types. In Nebraska, an abundance of livestock could help to reduce P. australis with proper timing and grazing intensities. In 2011, a 3-yr study was initiated to evaluate targeted cattle grazing and herbicide effects and the nutritive value of this species. Treatments included a single application of imazapyr (Habitat®, BASF Corporation, Research Triangle Park, NC) herbicide applied in the first year, grazing, and a control. Grazing was applied for up to five consecutive days in June and August 2011 and 2012 and in June 2013. Stem density, height, and biomass of P. australis were determined before each grazing period and in 2014. Diet samples were collected from rumenally fistulated steers each grazing period. Imazapyr provided 100% control of P. australis; however, re-establishment began 2 yr posttreatment. Grazing significantly reduced pregrazing P. australis biomass in the second and third growing season (P < 0.05). Stem density and height in the grazed treatment was similar to the control through 2012; however, in 2013 and 2014, control stem density was 1.5 times greater and height was 1.4 times that of the grazed treatment. Crude protein content of diet samples was greater in 2011 (16.8%) compared with 2012 (14.3%, P < 0.05). In vitro dry matter digestibility (IVDMD) of diet samples (45.4%) was not affected by year or month (P > 0.05). The relatively low IVDMD suggests that some form of energy supplementation would be needed to create a better nutritional balance. The cumulative effect of grazing does have the potential to reduce P. australis populations, but other methods would have to be used for greater control and site restoration.

Biomass of <i>Phragmites australis</i> and Effect Factors Analyzing in Zha Long Wetland

Phragmites australis are the typical vegetation in Zha Long National Natural Reserve. From August 10th to August 21st in 2006, we chose 60 quadrats in 15 sample sites, investigated the reed biomass, height, diameter, water nitrogen and phosphorus concentration. The results are as follow: 1) the average biomass of Phragmites australis models is 2858g•m-2 and the biomass between 15 sample sites is from 2029.0 to 4067.4 g•m-2; 2) the moisture content of Phragmites australis is from 42.95% to 64.95%. The average height of Phragmites australis is 272.47cm, and the average diameter of Phragmites australis is 0.51cm; 3) the NP weight ratio in each sample site concentrate from 9.18 to 15.79. Nitrogen is the most important limiting factor in Phragmites australis vegetation growing while phosphorus is not the limiting factor; 4) the Phragmites australis biomass is restricted by many factors especially water depth and water nitrogen concentration. But the phosphorus concentration in water has irrelativeness with Phragmites australis biomass.

Fire severity affects vegetation and seed bank in a wetland

Questions: How does the severity of prescribed fires affect vegetation and seed bank in a wetland? Location: A fire-prone reed swamp in northern Japan (250 ha, 40°49′N, 141°22′E, <10 m a.s.l.). Methods: Vegetation, biomass and seed bank were monitored for the 2 yr after annual prescribed fires were discontinued. Plant communities were placed into three categories based on fire severity: high (H) – fire consumed litter completely; moderate (M) – fire removed standing litter but left wet fallen litter; and low (L) – fire incompletely removed standing litter and did not remove fallen litter. Soil samples were collected in autumn 2007 and early summer 2008, and germinable seed bank was investigated by greenhouse trials. Results: High fire severity increased diversity in the next growing season by the establishment of short herbs in the standing vegetation. The biomass of forbs and grasses was greater in H where Phragmites australis biomass was reduced. The density of seed bank was >30 000 seeds m−2 throughout all the treatments. Perennial plants were dominant in the vegetation, while annuals, biennials and rushes were dominant in the seed bank. Small seeds were more abundant in the soil than in the litter. Qualitative and quantitative similarities between seed bank and the vegetation were low, and tended to be higher in H. Conclusions: Fire contributed to the development of diverse standing vegetation via the positive effects on seed bank dynamics, and can be considered a tool to maintain species-rich marshes.

The Biomass of Phragmites australis and Influencing Factors Analysis in Zha Long Wetland

Phragmites australis are the typical vegetation in Zha Long National Natural Reserve. From August 10 to August 21st in 2006, we chose 60 quadrats in 15 sample sites, investigated the reed biomass, height, diameter, water nitrogen and phosphorus concentration. The results are as follow: 1) the average biomass of Phragmites australis models is 2858g•m-2 and the biomass between 15 sample sites is from 2029.0 to 4067.4 g•m-2; 2) the moisture content of Phragmites australis is from 42.95% to 64.95%. The average height of Phragmites australis is 272.47cm, and the average diameter of Phragmites australis is 0.51cm; 3) the NP weight ratio in each sample site concentrate from 9.18 to 15.79. Nitrogen is the most important limiting factor in Phragmites australis vegetation growing while phosphorus is not the limiting factor; 4) the Phragmites australis biomass is restricted by many factors especially water depth and water nitrogen concentration. But the phosphorus concentration in water has irrelativeness with Phragmites australis biomass.

Effects of common reed (Phragmites australis) expansions on nitrogen dynamics of tidal marshes of the northeastern U.S.

Several recent studies indicate that the replacement of extant species withPhragmites australis can alter the size of nitrogen (N) pools and fluxes within tidal marshes. Some common effects ofP. australis expansion are increased standing stocks of N, greater differentiation of N concentrations between plant tissues (high N leaves and low N stems), and slower whole-plant decay rates than competing species (e.g.,Spartina, Typha spp.). Some of the greater differences between marsh types involveP. australis effects on extractable and porewater pools of dissolved inorganic nitrogen (DIN) and N mineralization rates. Brackish and salt marshes show higher concentrations of DIN in porewater beneathSpartina spp. relative toP. australis, but this is not observed in freshwater tidal marshes whenP. australis is compared withTypha spp. or mixed plant assemblages. With few studies of concurrent N fluxes, the net effect ofP. australis on marsh N budgets is difficult to quantify for single sites and even more so between sites. The magnitude and direction of impacts ofP. australis on N cycles appears to be system-specific, driven more by the system and species being invaded than byP. australis itself. WhereP. australis is found to affect N pools and fluxes, we suggest these alterations result from increased biomass (both aboveground and belowground) and increased allocation of that biomass to recalcitrant stems. Because N pools are commonly greater inP. australis than in most other communities (due to plant and litter uptake), one of the most critical questions remaining is “From where is the extra N inP. australis communities coming?” It is important to determine if the source of the new N is imported (e.g., anthropogenic) or internallyproduced (e.g., fixed, remineralized organic matter). In order to estimate net impacts ofP. australis on marsh N budgets, we suggest that further research be focused on the N source that supports high standing stocks of N inP. australis biomass (external input versus internal cycling) and the relative rates of N loss from different marshes (burial versus subsurface flow versus denitrification).

Rhizedra lutosa, a natural enemy ofPhragmites australis in North America

Rhizedra lutosa (Hubner) (Lepidoptera: Noctuidae), native to Europe, was first found in North America in 1988 in southern New Jersey. The insect is reported to cause serious damage toPhragmites australis in the Netherlands, but it now appears to be relatively unimportant throughout central Europe. We are investigating this insect as part of an effort to characterize existing natural enemies ofP. australis in North America toward a goal of biological control of this invasive plant. We trapped adults ofR. lutosa with blacklights in Rhode Island, Massachusetts, Connecticut, New York, Delaware, and Maryland; we also found it in Ohio and Pennsylvania.R. lutosa larvae feed in stems and rhizomes ofP. australis growing in dry sites. Based uponR. lutosa damage surveys andP. australis biomass measurements, we have determined that this insect does cause a reduction of plant growth in some sites, however, because of low moth densities, this effect is small. Despite spreading rapidly,R. lutosa densities do not appear to be increasing at sites we have investigated, and this insect does not currently appear to have much of an impact uponP. australis in North America.