Growth Characteristics and Salt Tolerance of Two Reciprocally Invasive Grass Species Found in Coastal Salt Marshes PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages : 230
Book Description
An invasive variety of the common reed Phragmites australis, the M haplotpye, has been implicated in the spread of this species into North American salt marshes normally dominated by the salt marsh grass Spartina alterniflora (smooth cordgrass). Phragmites australis is spreading into North American coastal marshes that are experiencing reduced salinities, while Spartina spp. are spreading into northern European brackish marshes that are experiencing increased salinities. We compared the salt tolerance and other growth characteristics of the invasive, M haplotype with two native haplotypes (F and AC) in greenhouse experiments. The M haplotype retained 50% of its growth potential up to 0.4 M NaCl, whereas the F and AC haplotypes did not grow above 0.1 M NaCl. The M haplotype produced more shoots per gram of rhizome tissue and had higher relative growth rates than the native haplotypes on both freshwater and saline water treatments. The M haplotype also differed from the native haplotypes in shoot water content and the biometrics of shoots and rhizomes. The results offer an explanation for how the M haplotype is able to spread in coastal salt marshes and support the conclusion of DNA analyses that the M haplotype is a distinct ecotype of P. australis. We then compared the growth, competitive ability, salt tolerance and osmotic adjustment of M haplotype P. australis and S. alterniflora along a salinity gradient in greenhouse experiments. Spartina alterniflora produced new biomass up to 0.60 M NaCl, whereas P. australis did not grow well above 0.2 M NaCl. When the two species were grown in mixed cultures, P. australis was less affected by competition than S. alterniflora at lower salinities but the competitive advantage reversed above 0.2 M NaCl. The greater salt tolerance of S. alterniflora compared to P. australis was due to its ability to use Na+ for osmotic adjustment in the shoots. On the other hand, at low salinities P. australis was more competitive because it produced more shoots per gram of rhizome tissue than S. alterniflora. These studies illustrate how ecophysiological differences shift the competitive advantage from one species to another along a salinity gradient.
Author: Publisher: ISBN: Category : Languages : en Pages : 230
Book Description
An invasive variety of the common reed Phragmites australis, the M haplotpye, has been implicated in the spread of this species into North American salt marshes normally dominated by the salt marsh grass Spartina alterniflora (smooth cordgrass). Phragmites australis is spreading into North American coastal marshes that are experiencing reduced salinities, while Spartina spp. are spreading into northern European brackish marshes that are experiencing increased salinities. We compared the salt tolerance and other growth characteristics of the invasive, M haplotype with two native haplotypes (F and AC) in greenhouse experiments. The M haplotype retained 50% of its growth potential up to 0.4 M NaCl, whereas the F and AC haplotypes did not grow above 0.1 M NaCl. The M haplotype produced more shoots per gram of rhizome tissue and had higher relative growth rates than the native haplotypes on both freshwater and saline water treatments. The M haplotype also differed from the native haplotypes in shoot water content and the biometrics of shoots and rhizomes. The results offer an explanation for how the M haplotype is able to spread in coastal salt marshes and support the conclusion of DNA analyses that the M haplotype is a distinct ecotype of P. australis. We then compared the growth, competitive ability, salt tolerance and osmotic adjustment of M haplotype P. australis and S. alterniflora along a salinity gradient in greenhouse experiments. Spartina alterniflora produced new biomass up to 0.60 M NaCl, whereas P. australis did not grow well above 0.2 M NaCl. When the two species were grown in mixed cultures, P. australis was less affected by competition than S. alterniflora at lower salinities but the competitive advantage reversed above 0.2 M NaCl. The greater salt tolerance of S. alterniflora compared to P. australis was due to its ability to use Na+ for osmotic adjustment in the shoots. On the other hand, at low salinities P. australis was more competitive because it produced more shoots per gram of rhizome tissue than S. alterniflora. These studies illustrate how ecophysiological differences shift the competitive advantage from one species to another along a salinity gradient.
Author: Tracy Elsey-Quirk Publisher: ISBN: 9781109671841 Category : Plant nutrients Languages : en Pages :
Book Description
This study examined both inter- and intraspecific variation of four dominant salt marsh macrophytes, a high marsh shrub, Baccharis halimifolia, a high marsh rush, Juncus roemerianus, a mid-marsh grass, Spartina patens, and the low marsh grass that is ubiquitous in wetlands along the Atlantic and Gulf coasts of the United States, short-form S. alterniflora. Chapter One evaluates the seasonal C pool dynamics of the four species including the seasonal allocation of above- and belowground C pools, C pool loss through decomposition, and soil C concentration in a wetland fringing Little Assawoman Bay, one of Delaware's Coastal Bays. To determine whether the rate of vertical accretion and organic matter accumulation differed between the low, S. alterniflora and high, J. roemerianus zones, soil cores from the two zones were used to measure 137 Cs and 210 Pb activity. Total plant C pools of the mid- and low marsh grass species, Spartina patens (4360 g C m -2) and Spartina alterniflora (4197 g C m -2), were similar and almost two and three times larger than total pools of Juncus roemerianus (2508 g C m -2) and Baccharis halimifolia (1490 g C m -2), respectively. Moving from the high to low marsh zones, the C pool shifted from primarily aboveground to belowground. Baccharis had the greatest aboveground C storage (1140 g m -2) and the slowest rate of C loss. Chapter Two examines interspecific variation in N pool dynamics in the four species including seasonal allocation of N pools above- and belowground, N loss through decomposition, N resorption efficiency, and soil N concentration. The seasonal fluctuation in the total N pools of the herbaceous species was due to belowground N pool dynamics, particularly fine root and dead large and small-sized macroorganic matter fluxes. Comparisons among the species revealed that the location, magnitude and timing of N storage and dispersal differed, which is important in the context of how species will shift in response to environmental change. Chapter Three describes the above- and belowground species associations in the fringing wetland and whether or not species shifts have occurred. Accurate productivity measurements in fringing wetlands may be dependent on species-specific organic matter separation, particularly belowground. Vegetation change in salt marshes may also become apparent when comparing above- and belowground species-specific live and dead organic matter. We surveyed species richness, frequency, and percent cover and measured above- and belowground biomass in three vegetation zones. Our study illustrates the importance of species-specific belowground biomass estimates to provide evidence of species shifts in both the low and high marsh zones. Chapter four examines intraspecific variation in morphological characteristics and carbon, nutrient, and mineral concentration and allocation within B. halimifolia, J. roemerianus, S. patens, and S. alterniflora. Ecotypic variation in morphology and composition and allocation of C, nutrients, and minerals in wetland plants may influence ecosystem functions such as the deposition and trapping of sediments, detritus production, secondary productivity, the cycling and storage of organic and inorganic nutrients, belowground organic matter production, and long-term C storage. We examined the expression of morphological traits and C, nutrient, and mineral composition and allocation among southern ecotypes, a tissue-culture regenerant, and a native mid-Atlantic ecotype for each of four salt marsh species after two growing seasons within natural stands in a mid-Atlantic salt marsh. Overall, we found that the expression of phenotypic variation was greatest in the low marsh, Spartina alterniflora than in the higher marsh species likely due to both the greater spatial variation in elevation and soil conditions in the higher marsh and potentially a lower tolerance of higher marsh species to environmental stress. The differences that we found among ecotypes have important implications for enhancing and developing ecosystem processes in restoration and creation projects. Chapter Five characterizes carbon pool dynamics of the salt marsh species, J. roemerianus, S. patens, and S. alterniflora using a STELLA model. The model was developed to examine the relationships between C pools and fluxes within species, to simultaneously compare the timing and magnitude of seasonal fluxes of C of each of the three species within a square meter, and to examine how changes to model parameters influence C pool dynamics and the accumulation of C belowground. (Abstract shortened by UMI.).
Author: Michael Kevin Rasser Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Salt marshes provide critical ecosystem services, such as shoreline stabilization, biogeochemical cycling and habitat for wildlife, to much of the world's population living on the coasts. Emergent vascular plants are a critical component of these ecosystems. This study was a comprehensive effort to gain a better understanding of the ecology of salt marsh plants in the Nueces River delta on the south Texas coast. This knowledge is essential to understand the potential anthropogenic impacts on salt marshes, including sea-level rise, global warming, reduced freshwater inflow and coastal erosion. A combination of remote sensing analysis, field studies and experiments were used to allow analysis across spatial scales ranging from landscape patterns of vegetation to leaf level measurements of the dominant species. A novel method of image classification was developed using high-resolution multi-spectral imagery integrated with ancillary data to map the major plant communities at a landscape scale. This included a high marsh assemblage composed primarily of Spartina spartinae and a low marsh community dominated by Borrichia frutescens and Salicornia virginica. Geospatial analysis determined that the location of these plant communities was related to the distance from the tidal creek network and elevation. The B. frutescens and S. virginica assemblage was more abundant at lower elevations along the waters edge, making it vulnerable to loss from shoreline erosion. At a finer spatial scale, gradient analysis was utilized to examine the relationship between elevation, which creates environmental gradients in salt marshes, and species distribution. I discovered that elevation differences of less than 5 cm can influence both individual species and plant community distribution. One interesting finding was that the two dominant species, B. frutescens and S. virginica, share similar responses along an elevation gradient yet are observed growing in monotypic adjacent zones. I constructed a large reciprocal transplant experiment, using 160 plants at 4 sites throughout the marsh, to determine what causes the zonation between these two species. The results of this study found that S. virginica fared well wherever it was transplanted but was a weak competitor. B. frutescens survival was significantly lower in the S. virginica zone than in its own zone suggesting that abiotic factors are important in determining the zonation of this species. However, high spatial and temporal variability existed in environmental parameters such as salinity. This variability may have been caused by the semi-arid climate and irregular flooding typical in the Nueces Marsh. Therefore, I utilized a greenhouse experiment to directly test the importance of the two dominant physical factors in salt marshes, flooding and salinity. The results found that for B. frutescens the effects of flooding were not significant, however salinity at 30% reduced growth. Salinity did not influence growth of S. virginica. The greater ability of S. virginica to tolerate salinity stress has important implications because reduced freshwater inflow or climate change can increase porewater salinity, thus favoring the expansion of S. virginica, and altering the plant community structure.
Author: Salman Gulzar Publisher: LAP Lambert Academic Publishing ISBN: 9783659260889 Category : Languages : en Pages : 208
Book Description
Halophytic grasses occur naturally along coastal and inland salt marsh and salt desert ecosystems around the world and have numerous benefits as fodder, turf grass or landscaping. Major limiting factors in salty ecosystems include reduced soil water availability and excessive salt levels. Plants vary in tolerance and in the exact suite of mechanisms to survive under these conditions. Early seed germination determines the ability of plants to colonize saline soils. Most commonly found grasses from Pakistani coast also vary in their ability to tolerate salinity at various stages of their life cycle. Seeds of Aeluropus lagopoides and Urochondra setulosa are highly salt tolerant both during storage in the soil and at growth, but are moderately salt tolerant during germination. Both are good candidates for landscape management along the Pakistani coast. Sporobolus ioclados is relatively less tolerant to salinity and could be ideal for dune stabilization and as a forage grass.
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Author: Tracy Elsey-Quirk
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Author: W. W. Woodhouse
Author: Michael Kevin Rasser
Author: James G. Gosselink
Author: John W. Barko
Author: Michael J. Ursin
Author: Salman Gulzar
Author: Eric Forest Zahn