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Ja Vymazal - One of the best experts on this subject based on the ideXlab platform.
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seasonal growth pattern of Phalaris arundinacea in constructed wetlands with horizontal subsurface flow
Ecological Engineering, 2015Co-Authors: Tereza Dvořakova řezinova, Ja VymazalAbstract:Abstract Plants play import role in constructed wetlands (CWs) with horizontal subsurface flow. It has been well documented that planted constructed wetlands are more efficient that filters with vegetation. Also, it has been found that plant species may differ in their effect on wastewater treatment. However, there has been little attention paid to the management of vegetation with the focus on enhanced nutrient removal. During the period April 2012–March 2013 seasonal development of aboveground biomass of Phalaris arundinacea (Reed canarygrass) has been evaluated at two constructed wetlands in the Czech Republic. Both systems were sampled on a monthly basis and triplicate samples were taken in both inflow and outflow zones. It has been found that the aboveground biomass was substantially higher in the inflow zone in both surveyed CWs and this phenomenon was also found in six other CWs where aboveground biomass was sampled during the peak biomass period. Besides that, it has been found that the peak biomass in the outflow zone occurred about two months later than in the inflow zone. This information could be used for biomass harvest management aimed at enhancing nutrient removal. The results of this study revealed that if inflow and outflow zones are harvested separately at different periods of the growing season, the amount of nitrogen and phosphorus removed via harvesting may increase up to 42% and 43%, respectively as compared to a single harvest of the whole surface of the filtration beds.
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evaluation of heavy metals seasonal accumulation in Phalaris arundinacea in a constructed treatment wetland
Ecological Engineering, 2015Co-Authors: Tereza Dvořakova řezinova, Ja VymazalAbstract:Constructed wetland for treatment of municipal wastewater was studied with focus on seasonal dynamics of heavy metals in the aboveground biomass of Phalaris arundinacea. Aboveground biomass was harvested and evaluated in one or two-month intervals during the period May 2011–March 2012 and concentrations of Cd, Cr, Cu, Ni, Pb, Zn were determined. Using the heavy metal concentration and biomass values, accumulation as standing stock was calculated for each heavy metal. The results indicated that maximum standing stock values occurred at different time for each heavy metals. The results therefore revealed that it is not easy to set the optimum time for aboveground biomass harvest in order to remove maximum of all heavy metals at one time. However, it seems that the harvest during the early growing season may be the most effective.
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competition of phragmites australis and Phalaris arundinacea in constructed wetlands with horizontal subsurface flow does it affect bod5 cod and tss removal
Ecological Engineering, 2014Co-Authors: Tereza Dvořakova řezinova, Ja VymazalAbstract:Abstract Phalaris arundinacea and Phragmites australis are frequently planted together in constructed wetlands for wastewater treatment in the Czech Republic. However, it has been observed that Phragmites usually outcompetes Phalaris over time but the speed of this process varies among systems. In this paper we evaluated the process of Phragmites encroachment into Phalaris stands in two constructed wetlands with horizontal subsurface flow. The results revealed that 50% of the area originally planted with Phalaris was overgrown by Phragmites in 5 and 9 years in the monitored systems while the complete elimination of Phalaris occurred after 9 and 13 years. Replacement of Phalaris did not have any effect on removal of BOD5 and COD while removal efficiency of TSS increased after Phalaris was replaced with Phragmites. However, it is difficult to determine out whether replacement was the only reason for better TSS removal.
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nitrogen and phosphorus standing stock in Phalaris arundinacea and phragmites australis in a constructed treatment wetland 3 year study
Archives of Agronomy and Soil Science, 2008Co-Authors: Ja Vymazal, Lenka KropfelovaAbstract:Constructed wetland with sub-surface horizontal flow at Břehov near Ceske Budějovice, Czech Republic is designed to treat sewage from 100 population equivalent. The system was put into operation in late 2003 and it consists of two rectangular beds (28 (L) × 9 (W) m each) planted with Reed canarygrass (Phalaris arundinacea) and Common reed (Phragmites australis) in bands parallel to the flow. Aboveground biomass of Phalaris and Phragmites was harvested in 2004, 2005 and 2006 during the peak standing crop of both species, i.e. in July for Phalaris and the early September for Phragmites. In 2004 and 2005, also belowground biomass was harvested. The major objective of the study was to evaluate the amount of nutrients sequestered in plant biomass and compare it with inflow loading. The analysis of the biomass indicated that the concentrations of nitrogen and phosphorus in various parts of both species were comparable in all three years. However, due to the higher biomass in 2005 and 2006 the nutrient standing ...
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growth of phragmites australis and Phalaris arundinacea in constructed wetlands for wastewater treatment in the czech republic
Ecological Engineering, 2005Co-Authors: Ja Vymazal, Lenka KrőpfelovaAbstract:Abstract Common reed (Phragmites australis) and reed canarygrass (Phalaris arundinacea) are two most commonly used plant species in constructed wetlands for wastewater treatment in the Czech Republic. Growth characteristics of both plants (biomass, stem count, and length) have been measured in 13 horizontal sub-surface flow constructed wetlands since 1992. The results revealed that while Phalaris usually reaches its maximum biomass as early as during the second growing season, Phragmites usually reaches its maximum only after three to four growing seasons. The maximum biomass of both species varies widely among systems and the highest measured values (5070 g m−2 for Phragmites and 1900 g m−2 for Phalaris) are similar to those found in eutrophic natural stands. The shoot count of Phragmites decreases after the second growing season while length and weight of individual shoots increases over time due to self-thinning process. Number of Phalaris shoots is the highest during the second season and then the shoot count remains about the same. Also the shoot length remains steady over years of constructed wetland operation.
Tereza Dvořakova řezinova - One of the best experts on this subject based on the ideXlab platform.
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seasonal growth pattern of Phalaris arundinacea in constructed wetlands with horizontal subsurface flow
Ecological Engineering, 2015Co-Authors: Tereza Dvořakova řezinova, Ja VymazalAbstract:Abstract Plants play import role in constructed wetlands (CWs) with horizontal subsurface flow. It has been well documented that planted constructed wetlands are more efficient that filters with vegetation. Also, it has been found that plant species may differ in their effect on wastewater treatment. However, there has been little attention paid to the management of vegetation with the focus on enhanced nutrient removal. During the period April 2012–March 2013 seasonal development of aboveground biomass of Phalaris arundinacea (Reed canarygrass) has been evaluated at two constructed wetlands in the Czech Republic. Both systems were sampled on a monthly basis and triplicate samples were taken in both inflow and outflow zones. It has been found that the aboveground biomass was substantially higher in the inflow zone in both surveyed CWs and this phenomenon was also found in six other CWs where aboveground biomass was sampled during the peak biomass period. Besides that, it has been found that the peak biomass in the outflow zone occurred about two months later than in the inflow zone. This information could be used for biomass harvest management aimed at enhancing nutrient removal. The results of this study revealed that if inflow and outflow zones are harvested separately at different periods of the growing season, the amount of nitrogen and phosphorus removed via harvesting may increase up to 42% and 43%, respectively as compared to a single harvest of the whole surface of the filtration beds.
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evaluation of heavy metals seasonal accumulation in Phalaris arundinacea in a constructed treatment wetland
Ecological Engineering, 2015Co-Authors: Tereza Dvořakova řezinova, Ja VymazalAbstract:Constructed wetland for treatment of municipal wastewater was studied with focus on seasonal dynamics of heavy metals in the aboveground biomass of Phalaris arundinacea. Aboveground biomass was harvested and evaluated in one or two-month intervals during the period May 2011–March 2012 and concentrations of Cd, Cr, Cu, Ni, Pb, Zn were determined. Using the heavy metal concentration and biomass values, accumulation as standing stock was calculated for each heavy metal. The results indicated that maximum standing stock values occurred at different time for each heavy metals. The results therefore revealed that it is not easy to set the optimum time for aboveground biomass harvest in order to remove maximum of all heavy metals at one time. However, it seems that the harvest during the early growing season may be the most effective.
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competition of phragmites australis and Phalaris arundinacea in constructed wetlands with horizontal subsurface flow does it affect bod5 cod and tss removal
Ecological Engineering, 2014Co-Authors: Tereza Dvořakova řezinova, Ja VymazalAbstract:Abstract Phalaris arundinacea and Phragmites australis are frequently planted together in constructed wetlands for wastewater treatment in the Czech Republic. However, it has been observed that Phragmites usually outcompetes Phalaris over time but the speed of this process varies among systems. In this paper we evaluated the process of Phragmites encroachment into Phalaris stands in two constructed wetlands with horizontal subsurface flow. The results revealed that 50% of the area originally planted with Phalaris was overgrown by Phragmites in 5 and 9 years in the monitored systems while the complete elimination of Phalaris occurred after 9 and 13 years. Replacement of Phalaris did not have any effect on removal of BOD5 and COD while removal efficiency of TSS increased after Phalaris was replaced with Phragmites. However, it is difficult to determine out whether replacement was the only reason for better TSS removal.
R A Culveno - One of the best experts on this subject based on the ideXlab platform.
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field evaluation of cocksfoot tall fescue and Phalaris for dry marginal environments of south eastern australia 1 establishment and herbage production
Journal of Agronomy and Crop Science, 2016Co-Authors: S G Clark, Richard Hayes, R A Culveno, Z N Nie, Carol Harris, Mark Norto, D L PartingtoAbstract:Newly developed candidate cultivars of cocksfoot (Dactylis glomerata L.), Phalaris (Phalaris aquatica L.) and tall fescue (Festuca arundinacea Schreb. = syn. L. arundinaceum (Schreb) Darbysh.) were evaluated over four years for persistence and productivity against current commercial cultivars in small plots at five locations selected for lower and less reliable rainfall and difficult soils (low pH and high Al) in south-eastern Australia known to be marginally too dry for these grass species. The five locations were - representing summer dominant rainfall, Inverell, in northern New South Wales (NSW); - representing uniform rainfall; Trungley Hall, (medium rainfall), and Beckom (lower rainfall) both in southern NSW; and; representing a winter dominant pattern - Eversley, (higher rainfall), and Bealiba, (lower rainfall), in central Victoria. The objective was to determine if the new candidate cultivars were more likely to persist and to be productive than current commercial cultivars. The study showed that most Phalaris and cocksfoot treatments were highly productive in high rainfall years at one or both sites in southern NSW. However, all treatments had become much less productive by the end of the experimental period due to plant loss under hot, dry conditions in the final summer. At Bealiba in central Victoria, cocksfoot was the most productive species with several cocksfoot treatments of both subsp. hispanica and subsp. glomerata still present at the final harvest despite a hot and dry final summer-autumn. Tall fescue was the most productive species in the two higher rainfall environments (Inverell, Eversley) although most treatments of all species performed well at those sites. Continental tall fescues were more productive on average than Mediterranean tall fescues at the strongly acidic Eversley site. As a result of this work, two of the new cocksfoot candidates (Moroccan Fine and AVH48 Selection) and one of the tall fescue candidates (Summer Active 1) have been licensed for commercial development and release.
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persistence traits in perennial pasture grasses the case of Phalaris Phalaris aquatica l
Crop & Pasture Science, 2014Co-Authors: R A Culveno, R J SimpsoAbstract:Persistence is consistently claimed by Australian farmers as a high priority for perennial grasses in long-term pastures. Phalaris (Phalaris aquatica L.) is a productive perennial grass with proven persistence in south-eastern Australia. Nevertheless, factors that determine the persistence of pasture species in southern Australia related to climate (drought), soil (acidity), grazing pressure, and, importantly, their interaction can reduce persistence of Phalaris and other species in various situations. These factors and their interactions are discussed in this review, and strategies to improve persistence with emphasis on plant breeding approaches are considered, with the most durable outcomes achieved when breeding and management options are employed concurrently. Two examples of breeding to improve persistence traits in Phalaris are described. A program to improve acid-soil tolerance resulted first in the release of cv. Landmaster, and recently Advanced AT, which is the most aluminium (Al)-tolerant cultivar of Phalaris to date. It was bred by recurrent selection on acid soils in a population containing genes from a related, more Al-tolerant species, P. arundinacea. The higher Al tolerance of cv. Advanced AT is of most benefit in more assured establishment on acid soils under variable moisture conditions and confers improved flexibility of sowing date. Cultivar Holdfast GT was bred to address complaints of poor persistence under heavy grazing by cultivars of the highly productive, winter-active type, since high grazing tolerance is needed to achieve profitable returns from developed pastureland. Evidence of good persistence under grazing for cv. Holdfast GT and possible tradeoffs with productivity are discussed. Maintaining high productivity under a predicted higher incidence of drought stress (climate change) and increasing areas of acid soils presents ongoing challenges for persistence in pastures.
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the first century of Phalaris aquatica l cultivation and genetic improvement a review
Crop & Pasture Science, 2009Co-Authors: R N Oram, R A Culveno, V Ferreira, A A Hopkins, A StewaAbstract:2006 marked the centenary of the commercial propagation of Phalaris (Phalaris aquatica L.) as a cultivated pasture plant, firstly in Australia, and soon after in New Zealand, South Africa, and North and South America. Small-scale evaluation of cv. Australian began in the Toowoomba Botanic Gardens, Queensland, in 1884. The first recorded large-scale production of seed was at the Glen Innes Research Farm of the NSW Department of Agriculture in February 1906. By 1908–15, several graziers in Australia and New Zealand sold seed widely within Australia, New Zealand, USA, Argentina, and South Africa. Factors affecting the utilisation of the original cultivar in Australia over the first half-century are reviewed. Thereafter, the need to extend the area of perennial pastures into regions unsuitable for cv. Australian led CSIRO and the US Department of Agriculture to collect germplasm widely in the Mediterranean region. Selection between and within Moroccan populations produced cvv. Sirocco and El Golea in Australia, and cv. Perla koleagrass in the USA. In Argentina, selection within cv. Australian produced the very successful, seed-retaining cv. Pergamino El Gaucho INTA, which was re-selected in Australia to produce cv. Seedmaster. The discovery of a single seed-retaining plant within a certified line of cv. Australian gave cv. Uneta, which had excellent seed retention because the rachillae of most seeds remained intact at maturity. In Australia, selection in populations derived from crosses between cv. Australian and Mediterranean ecotypes gave a succession of winter-active cultivars: Sirosa, Sirolan, Holdfast, Landmaster, Atlas PG, Advanced AT, and Holdfast GT. The latter 5 have Uneta-type seed retention, reduced tryptamine and tyramine alkaloids, and adaptation to different soil and climatic niches. Populations for the hotter, drier inland slopes of NSW are being field-tested. Also, a promising but unstable semi-dwarf line has been found: dwarfism appears to be caused by a transposable element. Breeding and selection programs in Argentina, several states of the USA, New Zealand, Israel, Tunisia, and Greece also produced cultivars with specific adaptations. Active breeding programs are continuing at Ardmore, OK, USA, and Pergamino, Argentina. A major remaining obstacle to the further improvement and utilisation of Phalaris is the unknown chemical nature of the toxin(s) causing ‘sudden death’, which temporarily interfere with nitrogen metabolism in the brains of herbivores, especially ruminants.
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persistence of winter active Phalaris breeding populations cultivars and other temperate grasses in diverse environments of south eastern australia
Animal Production Science, 2007Co-Authors: R A Culveno, S P Oschma, Kfm ReedAbstract:Three winter-active populations of Phalaris (Phalaris aquatica L.), selected over two generations for improved persistence under grazing, were evaluated with commercial cultivars of Phalaris and other temperate perennial grasses from 1999–2003 in three environments of south-eastern Australia as part of a program to develop a cultivar for more sustainable pastures and to assess genotype × environment interaction. Grazed sites were located at Bulart in western Victoria, and Rye Park on the Southern Tablelands and Tamworth on the North West Slopes of New South Wales. At the conclusion of the experiment, the frequency of live plant base was highest at Rye Park despite soil acidity and drought. Significant variance among half-sib families in each population was also observed most frequently at this site. Frequency was intermediate at Bulart but lower than expected considering high soil fertility, probably because of high grazing pressure. Frequency was lowest at Tamworth where severe drought occurred from 2001 onwards. There was significant genotype × environment interaction for frequency among half-sib families. Significant common family variance for frequency across the Bulart and Rye Park sites was demonstrated, but not between Tamworth and either of the other sites in later years. The relationship between winter herbage mass potential and persistence differed with population and site, and was negative for one population at Bulart but positive for another population at Tamworth. Mean persistence of all families was 30% higher than winter-active controls at Rye Park and at least 40% higher at Bulart. Phalaris generally persisted better than cultivars of tall fescue (Festuca arundinacea Schreb.), cocksfoot (Dactylis glomerata L.) and perennial ryegrass (Lolium perenne L.) with some exceptions, particularly at Bulart. Development of a winter-active Phalaris cultivar with improved persistence under grazing was considered possible for the Southern Tablelands and western Victorian environments with these populations but a separate program using additional germplasm will be needed for the North West Slopes environment.
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evaluation of Phalaris Phalaris aquatica l germplasm for persistence under grazing on the north west slopes new south wales
Crop & Pasture Science, 2005Co-Authors: R A Culveno, S P OschmaAbstract:The survival of available cultivars of introduced temperate perennial grasses has been less than adequate under grazing on the North-West Slopes of New South Wales. A wide range of germplasm of the Mediterranean perennial grass, Phalaris (Phalaris aquatica L.), was assessed for persistence, seedling vigour, winter yield potential, time of reproductive development, and summer dormancy in grazed swards at 3 sites (Manilla, Tamworth, Purlewaugh) from 1998 to 2001. The aim was to understand population characteristics that influence persistence in this environment and to identify persistent populations. Good establishment was achieved after above-average winter-spring rainfall in 1998. Persistence was high during the first year of grazing (1999) but declined under lower rainfall during 2000 at the Manilla and Tamworth sites. By 2001, a wide range in persistence had developed at these 2 sites. A group of wild populations, mainly from North Africa, was identified as being more persistent at both sites than any available cultivar. Two early cultivars, Sirocco and CPI 19305, were also relatively persistent. None of the germplasm survived a subsequent severe drought in 2002 at Manilla and Tamworth. Persistence remained high despite higher grazing pressure at the Purlewaugh site until the 2002 drought year, when changes in survival correlated with those at the other sites occurred. Biplot analysis indicated that early reproductive development and high summer dormancy were associated with persistence in both wild and bred populations. High seedling and winter growth potential was less strongly associated with persistence. Wild and bred germplasm from North Africa displayed these characteristics to a marked extent, whereas germplasm from southern Europe and Sardinia did not and was less persistent. A group of wild populations mainly from Morocco was identified as the basis for cultivar development.
D L Partingto - One of the best experts on this subject based on the ideXlab platform.
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field evaluation of cocksfoot tall fescue and Phalaris for dry marginal environments of south eastern australia 1 establishment and herbage production
Journal of Agronomy and Crop Science, 2016Co-Authors: S G Clark, Richard Hayes, R A Culveno, Z N Nie, Carol Harris, Mark Norto, D L PartingtoAbstract:Newly developed candidate cultivars of cocksfoot (Dactylis glomerata L.), Phalaris (Phalaris aquatica L.) and tall fescue (Festuca arundinacea Schreb. = syn. L. arundinaceum (Schreb) Darbysh.) were evaluated over four years for persistence and productivity against current commercial cultivars in small plots at five locations selected for lower and less reliable rainfall and difficult soils (low pH and high Al) in south-eastern Australia known to be marginally too dry for these grass species. The five locations were - representing summer dominant rainfall, Inverell, in northern New South Wales (NSW); - representing uniform rainfall; Trungley Hall, (medium rainfall), and Beckom (lower rainfall) both in southern NSW; and; representing a winter dominant pattern - Eversley, (higher rainfall), and Bealiba, (lower rainfall), in central Victoria. The objective was to determine if the new candidate cultivars were more likely to persist and to be productive than current commercial cultivars. The study showed that most Phalaris and cocksfoot treatments were highly productive in high rainfall years at one or both sites in southern NSW. However, all treatments had become much less productive by the end of the experimental period due to plant loss under hot, dry conditions in the final summer. At Bealiba in central Victoria, cocksfoot was the most productive species with several cocksfoot treatments of both subsp. hispanica and subsp. glomerata still present at the final harvest despite a hot and dry final summer-autumn. Tall fescue was the most productive species in the two higher rainfall environments (Inverell, Eversley) although most treatments of all species performed well at those sites. Continental tall fescues were more productive on average than Mediterranean tall fescues at the strongly acidic Eversley site. As a result of this work, two of the new cocksfoot candidates (Moroccan Fine and AVH48 Selection) and one of the tall fescue candidates (Summer Active 1) have been licensed for commercial development and release.
Joy Zedle - One of the best experts on this subject based on the ideXlab platform.
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set backs in replacing Phalaris arundinacea monotypes with sedge meadow vegetation
Restoration Ecology, 2010Co-Authors: Michael T Healy, Joy ZedleAbstract:Reed canary grass (Phalaris arundinacea) invades wetlands, forms monotypes, and resists control efforts, suggesting that strong feedbacks sustain its dominance, as in the alternative states model. In nine field experiments, we tested the hypothesis that applying a graminicide (sethoxydim) for three years would progressively reduce Phalaris abundance, and that seeding sedge meadow species (except grasses) would reestablish native plant dominance. The graminicide prevented Phalaris from flowering, reduced its height by 50% and reduced its cover, often to less than 40%. However, only two of the nine sites showed progressive declines over the three-year experiment. The first setback was that Phalaris recovered annually in nearly all treatment plots. A second setback was that seeding did not reestablish sedge meadow. In five sites, unseeded plots had similar numbers of native species as those seeded with either forbs, forbs and graminoids, or graminoids. In four formerly agricultural sites, however, non-native weeds increased in species richness and cover (a third setback). In only one site did the graminicide’s effect on Phalaris allow native species to increase in number and cover. But short-term gains were not long-lasting. In year four, three sites that developed high native-species cover were again strongly dominated by Phalaris (a fourth setback). The feedbacks that sustain this invader include resistance to the graminicide aboveground and rapid and robust regrowth from rhizomes and seeds belowground. The weak effect of this graminicide was a surprise; hence, we recommend stronger management actions to control Phalaris.
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understanding invasion as a process the case of Phalaris arundinacea in wet prairies
Biological Invasions, 2007Co-Authors: Suzanne M Kerche, Andrea Herrturoff, Joy ZedleAbstract:Invasive plants that most threaten biodiversity are those that rapidly form a monospecific stand, like the clonal grass, Phalaris arundinacea. Understanding complex and potentially interacting factors that are common in urban and agricultural landscapes and underlie rapid invasions requires an experimental, factorial approach. We tested the effects of flooding and nutrient and sediment additions (3 × 3 × 3 = 27 treatments, plus a control with no additions) on invasion of Phalaris into mesocosms containing wet prairie vegetation. We discovered a three-step invasion and degradation process: (1) initially, resident native species declined with prolonged flooding and sediment additions, and (2) prolonged flooding, sedimentation, and nutrients accelerated Phalaris aboveground growth; biomass rose to 430 times that of the control within just two growing seasons. The dramatic expansion of Phalaris in the second year resulted in the formation of monospecific stands in over one-third of the treatments, as (3) native species continued their decline in year 2. Disturbances acted alone and in combination to make the resident wetland community more invasible and Phalaris more aggressive, leading to monospecific stands. Yet, Phalaris did not always “win”: under the least disturbed conditions, the resident plant canopy remained dense and vigorous and Phalaris remained small. When anthropogenic disturbances coincide with increases in the gross supply of resources, more tolerant, fast-growing, and morphologically plastic plants like Phalaris can invade very rapidly. The fluctuating resource hypothesis should thus be refined to consider the role of interacting disturbances in facilitating invasions.
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does morphological plasticity of the Phalaris arundinacea canopy increase invasiveness
Plant Ecology, 2007Co-Authors: Andrea Herrturoff, Joy ZedleAbstract:Morphological plasticity could facilitate invasions of wetland plants into areas that experience increased durations of flooding and eutrophication. We explored canopy plasticity of Phalaris arundinacea, an aggressive invader of wetlands, as it differentially invaded wet prairie mesocosms under 3 flooding durations and 3 levels of nutrient addition. Phalaris grew as a sward with intermittent and early-season flooding but shifted to tussocks under constant flooding. These two growth forms differed by >20% in several canopy ratios. Clones that formed tussocks produced 45% more shoots per unit biomass (P = 0.007) and a 25% higher ratio of total shoot length to biomass (P = 0.04). Lighter-weight shoots supported 33% fewer leaves and, consequently, had 35% less leaf area per shoot height (P < 0.002). Tussocks developed a continuous mat of adventitious roots, with root mats reaching 20.9 ± 0.6 cm in diameter and 4.7 ± 0.3 cm in height over two growing seasons. While forming tussocks, Phalaris tolerated longer durations of flooding and more than doubled its aboveground biomass. Invasions occurred rapidly, with Phalaris exceeding 75% canopy cover and accounting for 66% of the total aboveground biomass under constant flooding. Early-season flooding increased the lateral spread of individual shoots. High nutrient addition produced shoots that were 27% taller and 50% heavier (P < 0.02), with 81% more leaf area (P < 0.0003) than shoots that received no nutrients. Consequently, under early-season flooding with high nutrient additions, Phalaris was primed to invade, nearly doubling its proportion of the total aboveground biomass and exceeding 50% canopy cover during year two.
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multiple disturbances accelerate invasion of reed canary grass Phalaris arundinacea l in a mesocosm study
Oecologia, 2004Co-Authors: Suzanne M Kerche, Joy ZedleAbstract:Disturbances that intensify with agriculture and/or urban development are thought to promote the spread of invasive plants, such as the clonal perennial reed canary grass ( Phalaris arundinacea L). To test this relationship and interactions among disturbances, we subjected wet prairie assemblages within 1.1 m2 mesocosms to invasion by Phalaris and addition of nutrients, sediments, and flooding. Species richness decreased with the application of sediments and/or flooding of 4 consecutive weeks or longer. Losses of up to six dominant and subdominant species in these treatments increased light transmission through the plant canopy by as much as 400% over the control. Light availability in July and September was a strong predictor of end-of-season aboveground biomass of Phalaris. Phalaris was also 35% and 195% more productive when nutrients were added at low and high levels, respectively. Multiple factors in combination were usually additive in their effects on invasion, but sediments and nutrients interacted with flood regime to synergistically increase invasion in some cases. A separate experiment likewise revealed a synergistic interaction between added nutrients and simulated grazing. We suggest that multiple factors be mitigated simultaneously to reduce invasion of Phalaris.
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relationships between canopy complexity and germination microsites for Phalaris arundinacea l
Oecologia, 2002Co-Authors: Roberto Lindigcisneros, Joy ZedleAbstract:Microsites that prevent seed germination are critical for slowing the invasion of native plant communities by aggressive, clonal species. A suitable model for study is the clonal grass, Phalaris arundinacea, which reproduces prolifically from seed and is spreading into wetlands across temperate North America. Knowing that light conditions control its seed germination in the laboratory and that light varies with canopy complexity in a Wisconsin fen, we tested multiple attributes of microsites under spatially and temporally dynamic canopies (namely, presence/absence of a matrix species, number of species in the canopy, plus indirect effects of three soil water levels) for their control of germination in microcosms. Our 6-species canopies + the matrix of Glyceria striata had the densest cover and reduced P. arundinacea germination to 1.9%, compared to 7.3% for 1-species canopies + the matrix. After selectively removing canopy components, germination increased to 36.1% for 6-species and 33.0% for 1-species canopies. Comparing canopies with each of the six species, germination declined in relation to increasing leaf width. Given moist soil, P. arundinacea germination microsites are determined by canopy complexity, which affects light penetration, which in turn determines germination rate.