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The Introduction and Spread of Smooth Cordgrass (Spartina alterniflora) in South San Francisco Bay
Abstract
Spartina alterniflora was first introduced into south San Francisco Bay in the 1970’s. Since that time it has spread to new areas within the south
bay and is especially well established at four sites. The spread of this introduced species was evaluated by comparing its
vegetative and reproductive characteristics to the native cordgrass, Spartina foliosa. The characters studied were intertidal distribution, phenology, aboveground and belowground biomass, growth rates, seed
production, and germination rates. Spartina alterniflora has a wider intertidal distribution than S. foliosa and outproduced the native cordgrass in all aspects that were studied. These results indicate that the introduced species
has a much better chance of becoming established in new areas than the native species, and once established, it spreads more
rapidly vegetatively than the native species. Spartina alterniflora is likely to continue to spread to new areas in the bay and displace the native plant. In addition, this introduced species may effect sedimentation
dynamics, available detritus, benthic algal production, wrack deposition and disturbance, habitat structure for native wetland
animals, benthic invertebrate populations, and shorebird and wading bird foraging areas. *** DIRECT SUPPORT *** A01BY058 00013
... One particular salt marsh grass that is distributed widely along the coast in the USA (Callaway and Josselyn 1992) and is vulnerable to sea-level rise is Spartina alterniflora. Spartina acts as an engineer by accreting sediment and increasing marsh surface elevation relative to mean tidal height (Ranwell 1964). ...
... Spartina alterniflora can reproduce by vegetative fragmentation, clonally via rhizomes, or sexually via pollination and seed production (Daehler and Strong 1996). Because sexual reproduction occurs annually (Callaway and Josselyn 1992), we track the population annually using discrete time (t). ...
... Sea-level rise may reverse the conditions that promote the spread of ecosystem engineers, and management of these populations will require in-depth consideration of these changes. For example, invasive marsh grasses that had spread rapidly with low rates of sea-level rise (Callaway and Josselyn 1992) may slow in their spatial advance under higher rates of sea-level rise. Alternatively, some invasive engineering populations that were spreading slowly when sea level was lower may suddenly spread rapidly as sea level rises. ...
Climate change and its consequences such as sea-level rise will modify environmental gradients, altering the spatial spread and persistence of plant populations. However, ecosystem engineers can also modify environmental gradients. To quantify the potential interactive effects of climate change and ecosystem engineering on population spread rates, we develop a spatial model that explicitly focuses on feedbacks between coastal vegetation growth and the environmental gradient of marsh elevation. We use the model to determine how sea-level rise could change how ecosystem engineering affects the spread rate of marsh populations. The model demonstrates that low levels of ecosystem engineering can produce the highest population spread rates in the absence of sea-level rise in initially low-elevation marshes. However, higher rates of ecosystem engineering and initially higher elevation marshes produce the highest population spread rates in the presence of sea-level rise. Sea-level rise can therefore reverse the conditions that drive high rates of spatial spread: engineers with low rates of spatial spread prior to sea-level rise may spread faster as sea levels rise. This result suggests that sea-level rise may promote the spread of invasive ecosystem engineers that previously experienced low rates of spatial spread. Moreover, ecosystem engineering can serve as a mechanism for adaptation to climate-driven changes in environmental gradients. Ecosystem engineering has the potential to rescue both native and exotic plant populations from climate-driven decreases in habitat suitability.
... More importantly, the aforementioned mechanistic models have overlooked a significant dynamic process: spatial competition. In many aquatic ecosystems, species richness is primarily driven by competition processes for resources (Callaway & Josselyn, 1992;Cardinale et al., 2009;Huisman et al., 1999;Sun et al., 1988). A recent competition-colonisation (C-C) model (Li et al., 2020) on the disturbance-diversity relationship has shown that disturbance and C-C tradeoffs can interact to facilitate different subsets of competitors to coexist (Liao et al., 2022). ...
... In addition, there is ample evidence for displacement competition among resource species. Examples include competition for light among periphyton or phytoplankton (Cardinale et al., 2009;Huisman et al., 1999), the inhibitory effect of water hyacinth on algae (Sun et al., 1988) and invasive smooth cordgrass competing with local aquatic plants (Callaway & Josselyn, 1992). These resource species can grow in streams, ponds, reservoirs, rivers and lakes, documenting the ubiquity of displacement competition in various aquatic ecosystems. ...
Ecologists have long sought to understand variation in food chain length (FCL) among natural ecosystems. Various drivers of FCL, including ecosystem size, resource productivity and disturbance, have been hypothesised. However, when results are aggregated across existing empirical studies from aquatic ecosystems, we observe mixed FCL responses to these drivers. To understand this variability, we develop a unified competition‐colonisation framework for complex food webs incorporating all of these drivers. With competition‐colonisation tradeoffs among basal species, our model predicts that increasing ecosystem size generally results in a monotonic increase in FCL, while FCL displays non‐linear, oscillatory responses to resource productivity or disturbance in large ecosystems featuring little disturbance or high productivity. Interestingly, such complex responses mirror patterns in empirical data. Therefore, this study offers a novel mechanistic explanation for observed variations in aquatic FCL driven by multiple environmental factors.
... Furthermore, it displays tall and short phenotypes, with the short phenotype likely reflecting less favorable environmental conditions (Anderson and Treshow, 1980;Zerebecki et al., 2021). Spartina alterniflora's asexual spread rates when colonizing intertidal soft sediments can be vigorous (134 ± 28 m y −1 ; Callaway and Josselyn, 1992), and its seeds can disperse up to hundreds of km via tidal currents (Morgan and Sytsma, 2013). Seedlings typically need more than one growing season to become as tall as mature plants (Redfield, 1972), and in appropriate elevations and edaphic conditions, they are more successful growing in bare spaces than under mature canopies (Metcalfe et al., 1986). ...
... Other studies have reported seedling colonization in the first-year post-restoration (van Proosdij et al., 2010), although seedling establishment of Spartina spp. can be erratic (Callaway and Josselyn, 1992). Clonal species are more often thought to transition from mostly sexual to asexual reproduction when establishing in a new site (Silvertown, 2008), which is opposite to what we observed during the Aulac restoration. ...
Vegetation patterns during salt marsh restoration reflect underlying processes related to colonization, reproduction, and interactions of halotolerant plants. Examining both pattern and process during recovery is valuable for understanding and managing salt marsh restoration projects. We present a decade of vegetation dynamics during salt marsh restoration (2011–2020) at a study site in the Bay of Fundy with megatidal amplitudes, strong currents, cold winter temperatures, and ice. We mainly investigated reproduction (asexual and sexual) and associated spread rates of Spartina grasses, and their health-related states (stem density, canopy height, and percent flowering) which help inform the probability of processes occurring. We also estimated modes of colonization and began quantifying the effects of interspecific interactions and environmental conditions on plant state. Spartina pectinata was the only pastureland plant to survive dike-breaching and saltwater intrusion in 2010; however, it was stunted compared to reference plants. Spartina pectinata patches remained consistent initially, before decreasing in size, and disappearing by the fifth year (2015). This early dynamic may provide initial protection to a developing salt marsh before Spartina alterniflora becomes established. Spartina alterniflora first colonized the sites in year 2 (2012), likely via deposition of rhizomal material, and then spread asexually before seedlings (sexual reproduction) appeared in year 4 (2014). Vegetation cover subsequently increased greatly until near-complete in year 9 (2019). The early successional dynamics of S. pectinata and S. alterniflora occurred spatially independently of each other, and likely contributed to sediment retention, creating an improved environment for S. patens, the dominant high marsh species in our region. Spartina patens have been slowly spreading into restoration sites from high elevation areas since year 6 (2016). We expect that competition between S. alterniflora and S. patens will result in the typical distinct zonation between high and low marsh zones. A next study will use the quantified processes for spatial-explicit modeling to simulate patterns of vegetation recovery, and to evaluate different salt marsh restoration strategies for the Bay of Fundy and elsewhere. Thus, proper identification and quantification of pattern-building processes in salt marsh vegetation recovery, the focus of our present study, was an essential step.
... Studies in Willapa Bay and San Francisco Bay have also shown that S. alterniflora eliminates native vegetation such as Zostera marina, Salicornia virginica, Triglochin maritima, Jaumea carnosa, and Fucus distichus (Scholten and Rozema, 1990;Simenstad and Thom, 1995;Daehler and Strong, 1996). Under certain conditions, S. alterniflora competes for space with native vegetation, occupying the bare tidal flat to form a single dense S. alterniflora community (Callaway and Josselyn, 1992). ...
... The saltmarsh coverage was approximately 3 km at this stage. In the fourth stage (for the future), assuming the exponential growth model for the expansion of S. alterniflora in a mudflat (Callaway and Josselyn, 1992), the distance between the S. alterniflora communities in the upper saltmarsh and pioneer zone will be gradually shortened as the tidal flat will continue to accumulate silts. S. alterniflora is expected to occupy most of the saltmarsh and the S. mariqueter habitat will migrate seaward. ...
A saltmarsh has developed rapidly on the mudflat of Andong Shoal, in southern Hangzhou Bay, over the last decade since embankment. The saltmarsh vegetation changes are driven by both sediment dynamic conditions and the competition between the exotic species Spartina alterniflora (S. alterniflora) and the native species Scirpus mariqueter (S. mariqueter). This study attempted to investigate large-scale spatial variations in the exotic and native species, by analyzing and interpreting a time series (2016 to 2018) of high-resolution (less than 1 m) remote sensing images. The total area of the saltmarsh increased at a rate of 1.07 km²/year, due to the accretion of the whole tidal flat. The spatial patterns revealed a new bimodal pattern for S. alterniflora invasion. S. alterniflora expanded over the upper to middle saltmarsh at a rate of 1.68 km²/year. However, the S. alterniflora patches at the seaward edge expanded at a negative rate of -0.005 km²/year, indicating a different pattern in competition: S. alterniflora had more advantages in the upper saltmarsh, while S. mariqueter had more advantages in the pioneer zone with low elevation. Consequently, S. alterniflora mainly established new habitats by invading S. mariqueter in the middle saltmarsh, but S. mariqueter occupied the bare mudflat for tradeoff. Our results also indicated that the interspecific competition result between S. alterniflora and S. mariqueter depended on elevation, and low elevation might create a favorable environment for S. mariqueter to win the competition with exotic species. This finding could be applied to future invasive species control and saltmarsh management.
... It is reported that the germination rate of Spartina alterniflora under constant temperature (25 °C), light (24 h-light), and aerobic conditions reaches to 80% 36 . In this study, maximum germination rate of the species under the light/dark and aerobic conditions without cold stratification was about 50% and less than 65-70% even after 4 or 8 weeks of cold stratification regardless of the temperature treatment (Fig. 1). ...
... In this study, maximum germination rate of the species under the light/dark and aerobic conditions without cold stratification was about 50% and less than 65-70% even after 4 or 8 weeks of cold stratification regardless of the temperature treatment (Fig. 1). The reason why the germination rate was relatively low in our study may be due to the short length of light treatment time (12-h per day) compared to a previous study (24-h per day) 36 , the seed status such as low proportion of matured seeds, and the timing of seed collection. Biber and Caldwell 1 reported that storm surges, waves, and strong winds associated with hurricanes and the subsequent drought directly and indirectly influenced seed production of S. alterniflora. ...
Spartina alterniflora, intentionally or unintentionally introduced worldwide, has adversely impacted local Japanese ecosystems. Thus, prediction of future distributions of S. alterniflora and its management are required. Local population expansion after establishment depends heavily on asexual (clonal) reproduction, whereas sexual (seed) reproduction is one of the critical factors for estimating invasion success and the likelihood of colonization to new habitats. However, knowledge about the germination characteristics of S. alterniflora is lacking. Here, we report the environmental conditions suitable for germination of S. alterniflora, under variable conditions of cold stratification periods (0, 4, 8 weeks), temperature (constant, alternating temperature), light (light/dark, dark), and oxygen (aerobic, anaerobic). Cumulative germination rate of S. alterniflora increased with an increasing period of cold stratification. Its seeds clearly preferred aerobic conditions to germinate. Also, the germination rate was higher under alternating temperature than under constant temperature regardless of light and oxygen conditions in any cold stratification period. However, long-term cold stratification, alternating temperature, and aerobic conditions were more important for germination of S. alterniflora than light. Removal of soil seed banks within 8 weeks of cold stratification after seed dispersals with matured seeds may be effective approaches for disrupting the germination of S. alterniflora.
... Invasive species accumulated more biomass than native species in mixed competition, as invaders had abilities of higher resource capture (e.g. light, nutrient and water) and faster growth than natives (Callaway and Josselyn, 1992;Daehler, 2003;Py sek and Richardson, 2007;van Kleunen et al., 2010). However, as the number of plant invasions is increasing, it appeared that invasive species can also interact with each other (Kuebbing and Nuñez, 2015;Rauschert and Shea, 2017). ...
... These results indicate that our invasive clonal species possessed higher growth ability and were competitively superior to natives in communities. That is consistent with many case studies where invasive species had higher resource uptake and faster growth ability than natives in pot and field experiments (Callaway and Josselyn, 1992;Daehler, 2003;Pellock et al., 2013;Py sek and Richardson, 2007;van Kleunen et al., 2010). In particular, with clonality invasive species can more efficiently capture and utilize resources (e.g. ...
... Salt marshes along the coast, dominated by salt-tolerant vegetation like herbs and low shrubs, are instrumental in maintaining ecosystem stability by capturing and binding sediments (Silvestri et al., 2005;Barbier et al., 2011). Initially, the introduction of the dominant perennial plant Spartina alterniflora to coastal marshes could stabilize the coast, reclaim tidal land, and alleviate saline soils (Callaway and Josselyn, 1992;Zhang et al., 2004). Competition and promotion between plants are observed during the introduction process. ...
The effect of invasive plants is mediated by their interactions with microbial communities. However, it is still uncertain how Spartina alterniflora impacts the arbuscular mycorrhizal fungi (AMF) community within the native rhizosphere what the resulting AMF differences are associated with. Here, we investigated what kind of AMF communities are formed in the roots of S. alterniflora to distinguish it from native plants such as Suaeda salsa, Phragmites australis, and Tamarix chinensis by analyzing the AMF communities and the associations with selected environmental factors. The dynamics of AM fungal communities are linked to plant-soil systems. The AMF communities of S. alterniflora and native vegetation demonstrated notable differences in composition, diversity, and symbiotic networks. Significantly higher ω, Ec, AN, AP, and AK were observed in S. alterniflora-invaded soils. Although plant rhizosphere AMF responded to soil environmental factors, AN and AP were highly explanatory environmental factors driving AMF community characteristics during S. alterniflora expansion, while increased soil P and N availability may be involved in shaping AMF community characteristics in S. alterniflora. Our findings can provide complementary evidence-based solutions for defending against invasive plants and mitigating their impacts, as well as protecting coastal ecosystems.
... Although the germination rate alone is not considered a definitive trait of invasion success [24,26], evidence suggests that several exotic species have higher germination percentages than their native counterparts [50]. This is the case for grasses such as Pennisetum setaceum compared to Heteropogon contortus in Hawaii [51], or the invasive Spartina alterniflora compared to its native congener Spartina foliosa in San Francisco Bay [52]. In Mexico, exotic species with high germination proportions have been reported, which may positively influence their post-introduction success [53,54]. ...
Germination traits are components of invasion potential, and comparing seed traits in sympatric native and invasive species can offer insights into the invasion process. We characterized seed germination traits and how they influenced the success of Eragrostis mexicana, a native species, and Eragrostis tenuifolia, an exotic species (Poaceae) in Mexico, in the context of their potential for biological invasion. Seeds from both species were collected from four sites in a natural protected area in Mexico City, and the germination of seeds of different ages was conducted in experiments at different temperatures. E. tenuifolia exhibited higher germination percentages than the native E. mexicana across all treatments. Seed age had differential effects, with older seeds of the native E. mexicana germinating better, while E. tenuifolia performed better with younger seeds. Temperature positively impacted germination for both species, although E. mexicana was limited at lower temperatures. Exotic E. tenuifolia can germinate over a wider temperature range with earlier germination rates, and generate a seed bank lasting several years, which may contribute to naturalization. The importance of germination traits in the context of invasive species establishment underscores the potential role of seed banks in facilitating biological invasions.
... These newly expanded S. alterni ora wetlands have largely encroached on the original coastal tidal ats (Mao et al. 2019). S. alterni ora's global distribution has occurred for several reasons, including its deliberate spread for erosion control and accretion for land reclamation, as well as accidental introductions via agriculture and ship ballasts (Callaway and Josselyn 1992; Li et al. 2009). S. alterni ora is strongly adaptable and tolerant, and possesses ecosystem engineering capabilities (van Hulzen et al. 2007) owing to its dense and stiff above-ground shoots. ...
Species invasion in salt marsh wetlands is known to disturb the balance of biotic and abiotic ecosystems (e.g., changing material exchange cycles and community structure). However, its influence on the morphological evolution of salt marshes is not yet understood in depth. This study investigates the long-term temporal and spatial distributions of an invasive plant— Spartina alterniflora ( S. alterniflora )—and its morphological characteristics in Yangtze Estuary by remote sensing imagery interpretation, tidal creek extraction, regional statistical analysis, and proximity analysis. The invaded site shows an area of S. alterniflora with a 35-fold increase from the start to the end of its initiation phase; it is the second biggest species in the study area. It is found that species invasion not only limited the expansion of native pioneer vegetation but also changed bio-geomorphic feedback loops. With the influence of plant invasion, median tidal creek lengths decreased and the median tidal creek sinuosity ratio remained stable, between 1.06 and 1.07 in the subarea. The method used here is adaptable to other salt marshes. The findings from this study can provide practical guidance for the restoration of native salt marshes in the estuary and thus control the spread of invasive species.
... Following a literature review of peak aboveground biomass, which included papers from most regions, with the exception of the Pacific Northwest, we confirmed the modeled peak aboveground biomass values were similar, and overlap with, field observations from the literature. In the California region, modeled values ranged from 321 to 2141 g m −2 , compared to field values ranging from 300 to 4316 g m −2 [77,78]. In the Northeast region, modeled values ranging from 167 to 1345 g m −2 were similar to field values, ranging from 207 to 1190 g m −2 [79]. ...
Accurate assessments of greenhouse gas emissions and carbon sequestration in natural ecosystems are necessary to develop climate mitigation strategies. Regional and national-level assessments of carbon sequestration require high-resolution data to be available for large areas, increasing the need for remote sensing products that quantify carbon stocks and fluxes. The Intergovernmental Panel on Climate Change (IPCC) provides guidelines on how to quantify carbon flux using land cover land change and biomass carbon stock information. Net primary productivity (NPP), carbon uptake, and storage in vegetation, can also be used to model net carbon sequestration and net carbon export from an ecosystem (net ecosystem carbon balance). While biomass and NPP map products for terrestrial ecosystems are available, there are currently no conterminous United States (CONUS) biomass carbon stock or NPP maps for tidal herbaceous marshes. In this study, we used peak soil adjusted vegetation index (SAVI) values, derived from Landsat 8 composites, and five other vegetation indices, plus a categorical variable for the CONUS region (Pacific Northwest, California, Northeast, Mid-Atlantic, South Atlantic-Gulf, or Everglades), to model spatially explicit aboveground peak biomass stocks in tidal marshes (i.e., tidal palustrine and estuarine herbaceous marshes) for the first time. Tidal marsh carbon conversion factors, root-to-shoot ratios, and vegetation turnover rates, were compiled from the literature and used to convert peak aboveground biomass to peak total (above- and belowground) biomass and NPP. An extensive literature search for aboveground turnover rates produced sparse and variable values; therefore, we used an informed assumption of a turnover rate of one crop per year for all CONUS tidal marshes. Due to the lack of turnover rate data, the NPP map is identical to the peak biomass carbon stock map. In reality, it is probable that turnover rate varies by region, given seasonal length differences; however, the NPP map provides the best available information on spatially explicit CONUS tidal marsh NPP. This study identifies gaps in the scientific knowledge, to support future studies in addressing this lack of turnover data. Across CONUS, average total peak biomass carbon stock in tidal marshes was 848 g C m−2 (871 g C m−2 in palustrine and 838 g C m−2 in estuarine marshes), and based on a median biomass turnover rate of 1, it is expected that the mean NPP annual flux for tidal marshes is similar (e.g., 848 g C m−2 y−1). Peak biomass carbon stocks in tidal marshes were lowest in the Florida Everglades region and highest in the California regions. These are the first fine-scale national maps of biomass carbon and NPP for tidal wetlands, spanning all of CONUS. These estimates of CONUS total peak biomass carbon stocks and NPP rates for tidal marshes can support regional- and national-scale assessments of greenhouse gas emissions, as well as natural resource management of coastal wetlands, as part of nature-based climate solution efforts.
... Las densas matas de vegetación que forman las plantas de Spartina, influyen de modo significativo en la acción del oleaje, disipándolo y dando como resultado una mayor deposición y acumulación de sedimentos, lo que altera los perfiles de la playa que se hacen más pronunciados y acantilados. Un impacto secundario del acrecentamiento de los sedimentos genera cambios en los patrones de circulación del agua reduciendo el flujo de las mareas, lo que conduce a incrementar las inundaciones; en especial, durante los periodos de abundante precipitación (Callaway y Josselyn, 1992). ...
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... In contrast, S. alterniflora replaces many native species and becomes the dominant species in the local ecosystem of salt marshes of the intertidal zone because of its stout stems and strong roots, which are resistant to salt and sea flooding and hence, it has a high reproductive capacity (Zhang et al., 2004;Du et al., 2019). To date, S. alterniflora has invaded and expanded its distribution in salt marshes and tidal flats in many regions of the world, including the west coast of the United States (Spicher and Josselyn, 1985;Callaway and Josselyn, 1992), Northern Europe (Baumel et al., 2003), South Africa (Adams et al., 2012), New Zealand (Partridge, 1987), China , and Japan (Kimura et al., 2016). The rapid expansion of this plant is now considered a threat to coastal environments . ...
Spartina alterniflora is a halophytic perennial grass species that has invaded coastal wetlands worldwide, including tidal flats in Japan. Rapid removal or eradication of invasive plants is desirable because of their severe ecological impact on local ecosystems. Seed germination is the main cause of its distribution and invasion. Understanding germination characteristics of S. alterniflora is critical for the prediction and early detection of its populations in new environments. Therefore, we aimed to investigate the effects of salinity (0, 10 20, 30, and 40 g/L artificial seawater), temperature (15, 20, 25 °C for constant, and 15/25 °C for alternating), and seed immersion (5 ml and 40 ml medium) based on laboratory experiments to evaluate the physicochemical environmental factors that facilitate the germination of S. alterniflora seeds. The cumulative germination rate and mean germination time were significantly affected by temperature and salinity but not by immersion. Increased salinity gradually reduced the cumulative germination rate in all temperature and immersion conditions. The mean germination time tended to be prolonged with the salinity level. A constant temperature of 25 °C promoted higher seed germination compared to constant temperatures of 15 and 20 °C. Notably, alternating temperature between 15 and 25 °C induced a higher seed germination compared to other constant temperatures. In addition, alternating temperatures varied the mean germination time to facilitate sensitivity to salinity, indicating that temperature fluctuation is a key factor that stimulates seed germination of S. alterniflora. These results suggest that S. alterniflora seeds prefer gaps in vegetation canopies and a low depth of burial in soil. Further studies are needed to analyze prevention strategies for the eradication of this invasive species in Japan.
... First, S. alterniflora inhabited the low water level and occupied some niches formerly belonging to S. salsa. Furthermore, S. alterniflora community plants are dense and tall, covering S. salsa and weakening its utilization of sunlight resources (Callaway and Josselyn, 1992). According to Table 5, during 2017-2019, in the middle of the study area, approximately 290.93 hm 2 of S. salsa habitat was shifted into S. alterniflora. ...
Spartina alterniflora (S. alterniflora) was introduced into China in the 1980s to control coastal erosion. However, it has significant negative impacts on coastal wetlands by encroaching on the habitat of native plant communities, which has seriously threatened coastal wetland function and biodiversity maintenance. The core area of the Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China was taken as the study area and GF-2 remote sensing images from 2017, 2019 and 2020 were selected in this study. By using U-Net, this study extracted habitat information, identified the variation in habitat pattern, investigated interspecific competition and the characteristics of habitat type shifts. The results indicated that the U-Net model showed excellent classification performance, with the highest F1-score and MIoU. The habitat of S. alterniflora expanded and increased from 3,920 to 4,350 hm 2 between 2017 and 2020. The habitat of Suaeda salsa (S. salsa) continuously fragmented and had been reduced to 1,414 hm 2 by 2020. The degree of habitat fragmentation in the core area was strengthened and heterogeneity was enhanced. Moreover, while the competition between S. alterniflora and Phragmites australis (P. australis) was intensifying, both encroached on the habitat of S. salsa, which aggravated the reduction and fragmentation of the habitat of S. salsa, causing the loss of food and habitat of red-crowned cranes and further threatening biodiversity maintenance and ecosystem stability. These results can offer new insights on the habitat competitive mechanism among native plant communities and alien invasive species in the coastal wetland under global warming and anthropogenic influences.
... Invasion by S. alterniflora is a threat to estuarine biodiversity as the species is very productive and forms dense monospecific stands that often supplant intertidal mudflat and resident salt marsh communities (Daehler and Strong 1996;Neira et al. 2006). The potential impacts of this species can be seen in San Francisco Bay, United States of America, where it was intentionally introduced by the Army Corps of Engineers as an experiment in marsh restoration (Callaway and Josselyn 1992). However, the species continued to spread and re-engineer the ecosystem. ...
Major threats to South African estuaries include freshwater flow alterations, urbanisation, habitat transformation, deteriorating water quality, increased biological invasions and resource over-exploitation. Although South African estuary restoration is in its infancy, important lessons have been learnt through past efforts undertaken in some of the most impacted systems. This review presents case studies focused on hydrological and physical restoration actions, while recognizing the need to implement urgent remedial measures to restore the populations of targeted estuary-associated marine fish species. Common interventions designed to arrest declining estuary health include artificial management of estuary mouths and the use of artificial structures to restore tidal action and remediate erosion damage. Limited natural habitat restoration actions have been conducted on the subcontinent. Fortunately, estuaries are resilient ecosystems and can recover fairly rapidly if appropriate restoration interventions are successfully applied. Restoration needs to be co-ordinated through a national strategy which is currently not in place. It is particularly important to address the root cause of deterioration through active restoration and/or rehabilitation measures rather than only managing symptoms. The implementation of existing and future conservation legislation regarding the exploitation of natural resources within estuaries needs to be prioritised, so that over-exploited angling and subsistence fish species populations can recover.
... Previous investigations on the phenology of invasive S. alterniflora salt marshes have mostly relied on field observations (Somers & Grant, 1981;Callaway & Josselyn, 1992) or medium-spatial-resolution remote sensing imagery at large-scale . To the best of our knowledge, our study presents the first attempt to investigate local scale spatial heterogeneities in S. alterniflora marshes based on high spatial resolution satellite imagery. ...
The rapid expansion of invasive Spartina alterniflora in China’s coastal wetlands has seriously threatened regional ecosystem health. Characterizing phenology of S. alterniflora salt marshes supports the studies on plant invasion mechanism and carbon fluxes in coastal wetlands. To date, little is known about the capacity of high-spatial-resolution imagery in revealing local scale heterogeneities and temporal variations in the phenology; in addition, the driving factors of such heterogeneities are not well understood. This study took Yellow River Estuary (YRE) as the study site where S. alterniflora area has expanded since 2008. We retrieved start of season (SOS), end of season (EOS), length of growing season (LOS), and maximum Normalized Difference Vegetation Index (NDVImax) from time series Sentinel-2 imagery (10-meter resolution) during 2017 ∼ 2019 with assist of a rule-based data noise removal approach. Results showed that phenological metrics differ with invasion years. The differences in the median NDVImax reached 0.13, in the median SOS reached 26 days, and in the median LOS reached 51 days. S. alterniflora with 5-year invasion had the highest NDVImax, and younger S. alterniflora marshes had earlier SOS and longer LOS. Both SOS and EOS showed negative relationships with NDVImax, indicating the marshes with greater green vegetation cover had earlier SOS and EOS. More spatial details can be revealed from higher-resolution PlanetScope imagery (3-meter resolution), showing the influence of tidal creeks on phenology. The spatial heterogeneity in phenology was associated with environmental factors such as tidal inundation, elevation, micro-climate, nutrients, and canopy structure. S. alterniflora showed markedly higher NDVImax and earlier EOS in 2018 compared to 2017 and 2019, associated with larger river water discharge and sediment load brought by Water Sediment Regulation Scheme, greater precipitation in the wettest season and lower preseason temperature in 2018. Large phenological variations at both spatial and temporal scales suggest that S. alterniflora marshes are sensitive to the local environment and climate change. This study has the potential to provide references for the management of invasive plants threatening coastal wetlands in the world.
... It may be because S. alterniflora was first introduced in the Fujian province, and gradually spread from the middle to the north and south. According to the literature, S. alterniflora has a robust sexual reproduction ability in North America, which is related to its geographical distribution and plays an important role in population spread and invasion (Callaway and Josselyn, 1992;Plyler and Carrick, 1993). In addition, S. alterniflora seeds have extremely strong salt tolerance characteristics and maintain high activity after soaking in 2-4 • C seawater for 3 months, and their germination ability reaches the maximum (Mooring et al., 1971). ...
Spartina alterniflora is a perennial herb native to the American Atlantic coast and is the dominant plant in coastal intertidal wetlands. Since its introduction to China in 1979, it has quickly spread along the coast and has caused various hazards. To control the further spread of S. alterniflora in China, we first reconstructed the history of the spread of S. alterniflora in its invasion and origin countries. We found that S. alterniflora spreads from the central coast to both sides of the coast in China, while it spreads from the west coast to the east coast in America. Furthermore, by comparing 19 environmental variables of S. alterniflora in its invasion and origin countries, it was found that S. alterniflora is more and more adaptable to the high temperature and dry environment in the invasion country. Finally, we predicted the suitable areas for this species in China and America using the maximum entropy (MaxEnt) model and ArcGIS. Overall, through analysis on the dynamic and trend of environmental characteristics during the invasion of S. alterniflora and predicting its suitable area in the invasion area, it guides preventing its reintroduction and preventing its further spread of the species has been found. It has reference significance for studying other similar alien plants and essential enlightening relevance to its invasion and spread in similar areas.
... As a biotic invader, S. alterniflora competes with native plants, threatens native ecosystems and coastal aquaculture, and may cause local biodiversity to decline (Callaway and Josselyn, 1992;Daehler and Strong, 1996;Brusati and Grosholz, 2007;Zuo et al., 2012). The introduction of S. alterniflora resulted in a significant decrease of abundance, coverage, and seed and fresh corm output of Scirpus mariqueter which is a native species of sedge in Dongtan of Chongming Island (Chen et al., 2004;Wang et al., 2012). ...
Seagrass meadows are critical ecosystems, and they are among the most threatened habitats on the planet. As an anthropogenic biotic invader, Spartina alterniflora Loisel. competes with native plants, threatens native ecosystems and coastal aquaculture, and may cause local biodiversity to decline. The distribution area of the exotic species S. alterniflora in the Yellow River Delta had been expanding to ca.4,000 ha from 1990 to 2018. In this study, we reported, for the first time, the competitive effects of the exotic plant (S. alterniflora) on seagrass (Zostera japonica Asch. & Graebn.) by field investigation and a transplant experiment in the Yellow River Delta. Within the first 3 months of the field experiment, S. alterniflora had pushed forward 14 m into the Z. japonica distribution region. In the study region, the area of S. alterniflora in 2019 increased by 516 times compared with its initial area in 2015. Inhibition of Z. japonica growth increased with the invasion of S. alterniflora. Z. japonica had been degrading significantly under the pressure of S. alterniflora invasion. S. alterniflora propagates sexually via seeds for long distance invasion and asexually by tillers and rhizomes for short distance invasion. Our results describe the invasion pattern of S. alterniflora and can be used to develop strategies for prevention and control of S. alterniflora invasion.
... marshes are Spartina, Phragmites, Scirpus, and other speices, such as Suaeda, Cyperus and Thatch. However, some evidence has been reported that, as an exotic species, Spartina, may compete with native plants, threaten native ecosystems and coastal aquaculture, and cause declines in local biodiversity (Brusati and Grosholza, 2007;Callaway and Josselyn, 1992;Daehler et al., 1996;Chen et al., 2005;Rosso et al., 2006;Wang et al., 2006;He et al., 2007;Huang and Zhang, 2007;Li and Zhang, 2008). The invasion and control of Spartina has been become a hot topic and drawn attention from biologists and ecologists in China and abroad worldwide (Thomas and Reid, 2007). ...
Based on the cloud platform of Google Earth Engine (GEE), this study selected Landsat 5/8 and Sentinel-2 remote sensing images and used Support Vector Machine (SVM) classification method to classify the 35 years of intertidal salt marshes in China, and verified the classification results in combination with field survey. Finally, combining with various driving factors, the reasons and laws affecting the changes of salt marshes species and area were discussed and analyzed. The main results of the study are as follows:The main types of salt marshes plants in China include Phragmites australis, Spartina alterniflora, Suaeda salsa, Scirpus mariquete, Tamarix chinensis, Cyperus malaccensis and Sesuvium portulacastrum. The results salt marshes classification indicated that 166999.32 ha in 1985, 172893.87 ha in 1990, 174952.29 ha in 1995, 125567.51 ha in 2000, 93257.97 ha in 2005, 102539.04 ha in 2010, 96302.92 ha in 2015, and 115722.75 ha in 2019. The main driving factors of salt marsh change from 1985 to 2015 are reclamation, mudflat aquaculture, climate change, coastal zone erosion, invasion of alien species, and natural competition and succession among salt marshes species. The results can be used to quantitatively analyze the salt marshes carbon storage in space and time, and provide data support for the protection of salt marsh wetlands, the restoration of ecological functions and the implementation of "carbon neutral".
... Spartina is a genus of perennial rhizomatous polyploid C 4 grasses containing around fifteen species, including a number of hybrids (Ainouche et al. 2009;Strong and Ayres 2013;Bortolus et al. 2019). Most Spartina species are primary colonists of intertidal mud flats and have been intentionally introduced to many parts of the world due to their ability to trap sediment and thereby stabilise eroding shorelines, reclaim land and provide defence against extreme coastal weather events (Callaway and Josselyn 1992). ...
Non-native plants may benefit, briefly or permanently, from natural enemy release in their invaded range, or may form novel interactions with native enemy species. Likewise, newly arrived herbivores may develop novel associations with native plants or, where their hosts have arrived ahead of them, re-establish interactions that existed previously in their ancestral ranges. Predicting outcomes from this diversity of novel and re-established interactions between plants and their herbivores presents a major challenge for invasion biology. We report on interactions between the recently arrived invasive planthopper Prokelisia marginata, and the multi-ploidy Spartina complex of four native and introduced species in Britain, each representing a different level of shared evolutionary history with the herbivore. As predicted, S. alterniflora, the ancestral host, was least impacted by planthopper herbivory, with the previously unexposed native S. maritima, a nationally threatened species, suffering the greatest impacts on leaf length gain, new leaf growth and relative water content. Contrary to expectations , glasshouse trials showed P. marginata to preferentially oviposit on the invasive allododecaploid S. anglica, on which it achieved earlier egg hatch, faster nymphal development, larger female body size and greatest final population size. We suggest P. marginata is in the process of rapid adaptation to maximise its performance on what is now the most abundant and widespread host in Britain. The diversity of novel and re-established interactions of the herbivore with this multi-ploidy complex makes this a highly valuable system for the study of the evolutionary ecology of plant-insect interactions and their influence on invasion dynamics.
... The authors presented a sequence of aerial photographs of an intertidal landscape, in which distinct patches of vegetation grew and merged over a timespan of seven years (see Fig. 1 in the authors' work). Similarly, through aerial photographs recorded over several years, Callaway and Josselyn (1992) and Schwarz et al. (2016) both observed the merger of initially distinct patches of marsh vegetation. In two river reaches in the UK, Cotton et al. (2006) studied the seasonal growth of Ranunculus and its impact on flow and sediment deposition. ...
Laboratory experiments examined how the hydrodynamic interaction between neighboring patches of model vegetation impacted deposition and the potential for patch expansion. The evolution of the vegetated region was modeled experimentally by introducing new artificial vegetation into regions of enhanced deposition. The study began with a pair of side-by-side, circular patches, each of diameter D =10.5 cm, constructed from circular cylinders (d = 3.2 mm) that extended through the flow depth. The interaction between the patches generated a zone of enhanced deposition on the centerline between the patches, and this zone had a much greater longitudinal extent than the region of enhanced deposition formed behind an individual patch. This suggested that the interaction between patches could enhance streamwise growth. In addition, deposition on the centerline eventually led to the merger of the two adjacent patches, a mechanism for lateral patch growth. Finally, regions of diminished velocity on the outside edge of the patch pair were observed to enhance deposition over a lateral distance of 0.5D. These observations of lateral growth stand in contrast to previous descriptions of vegetation-flow interaction that emphasize negative feedbacks for lateral growth and positive feedbacks only for streamwise growth. Although lateral growth was observed, the tendency for enhanced deposition (growth) extended much farther in the streamwise direction (40D) than in the lateral direction (0.5D), such that vegetation expansion was dominated by streamwise growth.
... Its roles as an ecological engineer are very significant. Some current evidence has shown geomorphological changes in coastal ecosystems after being invaded by cordgrass (Callaway and Josselyn, 1992;Crooks, 2002). Simultaneously, the success of cordgrass invasion in China threatens the capacity of C sequestration in mangrove wetlands (Wang et al., 2019). ...
Mangroves and tidal saltmarshes are known for their considerable capacity to store carbon (C). Mangrove-saltmarsh ecotones have high dynamics in C cycling based on some evidence of mangroves encroaching into saltmarshes. The mangrove encroachment may also increase the surface elevation, enhance C storage and further change the ecosystem services. In China, an exotic Spartina alterniflora (cordgrass) introduced from the East Coast of the United States has been extensively invading mangrove wetlands. During this situation, the carbon dynamics and associated sedimentary processes within the mangrove wetlands under cordgrass invasion are largely unknown. In this chapter, we discuss the biochemical and eco-geomorphological feedbacks related to surface sediment carbon and discuss the biological factors affecting sediment carbon flux, vegetation-sediment interaction and the consequent sedimentary processes. We assess the change in carbon stocks after cordgrass invaded mangroves in the Yunxiao Estuary and present a conceptual model of carbon dynamics and the evaluation of regional carbon storage in typical mangrove-Spartina ecotones. The invasion of cordgrass can increase the sediment deposition and enhance the surface elevation on the edges of mangrove-Spartina ecotones, which has a positive feedback on their further expansion to the mudflat. Thus, cordgrass invasion in the mangroves in China would enhance sediment C stocks in the mangrove wetlands. However, the long-term studies of the C dynamics in mangrove-Spartina ecotones still require truly interdisciplinary approaches of biology, biochemistry and eco-geomorphology.
... S. alterniflora has a certain wave-slowing effect, which can promote bank consolidation, but it also affects the development of tidal creek and is not conducive to hydrological connectivity. In addition, the invasion of S. alterniflora has reduced the distribution of native species, endangered biodiversity, occupied the light beach, and caused the loss of bird habitats and food sources, such as rare birds-redcrowned cranes and black-billed gulls that depend on the habitat of Suaeda salsa (Callaway & Josselyn, 1992;Gallardo, Clavero, Sanchez, & Vilà, 2016;Guy-Haim et al., 2018). Prevention and management measures should be taken in time to suppress the invasion of S. alterniflora. ...
As the main invasive plant species in the Yellow River Delta, Spartina alterniflora (S. alterniflora) has been a great threat to local ecosystems, but there are few studies on the growth scale, habitat structural changes, and expansion pattern of S. alterniflora. In this study, the native and invasive species in the Yellow River Delta were examined for their spatiotemporal characteristics and succession patterns. First, multi‐temporal SENTINEL‐2 and LANDSAT‐8 images from 2018 were selected. A random forest algorithm was used to verify the image spectral band's significance and separability to determine the native and invasive species. Then, the spatiotemporal variation of habitat structure of the species was discussed in depth from the perspective of landscape ecology. Finally, the expansion direction and expansion mode of S. alterniflora were further analyzed. The main results obtained were as follows: (a) SENTINEL‐2 images with red‐edge bands had obvious advantages in vegetation community extraction as compared to LANDSAT‐8 images (SENTINEL‐2, OA = 82.86%, kappa coefficient = 0.79; LANDSAT‐8, OA = 78.77%, kappa coefficient = 0.74). (b) The expansion pattern of the S. alterniflora community became spatially continuous, more regularized, and aggregated over time. (c) The expansion in the north shore mainly faced toward the sea, and the south bank mainly faced toward the land, and this phenomenon was closely related to the sedimentation of the Yellow River Delta. Marginal and external expansion both occurred, but marginal expansion predominated. The results have important theoretical and scientific value for the environmental protection and sustainable development of the entire Yellow River Delta.
... However, 3-oxo-modified AHLs were not detected in the non-rhizosphere soils, which might be due to the anaerobic environment. AHLs concentrations were lower in S. mariqueter rhizosphere than in S. alterniflora and P. australis rhizosphere, which could be explained by the higher levels of root system development for the latter two than for the former (Callaway and Josselyn 1992;Emery and Fulweiler 2014). AHLs accumulation may be affected by environmental factors (Fuqua et al. 2001). ...
AimsN-acyl-L-homoserine lactones (AHLs) based quorum sensing (QS) phenomenon is recognized as an effective agent for regulating bacterial growth and metabolism. However, diversity and biological role of AHLs in natural environments remain largely unknown. This study focuses on compositions of AHLs and their potential role in nitrogen transformation in intertidal marshes.Methods
We investigated the levels of AHLs in rhizosphere (Phragmites australis, Spartina alterniflora and Scirpus mariqueter) and non-rhizosphere soils from Chongming eastern intertidal wetland of the Yangtze Estuary using gas chromatography-mass spectrometry (GC/MS). Molecular techniques were employed to investigate the compositions and structure of bacterial community. Soil-slurry experiments in combination with nitrogen isotope tracing technique were conducted to examine the effects of AHLs on nitrogen transformation processes.ResultsAHLs were higher in rhizosphere than non-rhizosphere soils, and correlated significantly with soil organic carbon and pH. C6-, C8-, C10- and C12-HSLs were identified as the probably universal QS signal molecules in intertidal marsh soils. The bacterial biodiversity might be regulated by AHLs, and 12 of the 50 most abundant microorganisms in intertidal marsh soils were related significantly with AHL concentrations. Furthermore, C6-, C8- and C12-HSLs might play an important role in mediating nitrogen transformation processes including nitrification, denitrification and anaerobic ammonium oxidation (anammox).ConclusionsAHLs are favored to accumulate in rhizospheric environments and thus further mediate the bacterial diversity and soil nitrogen cycling. This study highlights the associations of QS signal molecules with the dynamics and activity of nitrogen cycling bacteria in intertidal marshes.
... With a great capacity for decreasing tidal velocity, mitigating erosion, and trapping sediments, S. alterniflora has been introduced to many coastal regions in the world to protect dikes and promote silting for natural reclamation [65], which turned out to be successful to some extent. The plant did reduce the influence of typhoons and protect the coastal environment of Zhejiang against typhoons in 1990 and 1994 [66]. ...
Tidal flats, which are non-vegetated land–sea transition areas, have an important ecological function in the global ecosystem. However, they have been shrinking in recent years due to natural and anthropogenic activities. Although many studies focus on tidal flats in the Yangtze River estuary (YRE) in China, how reclamation and plant invasion affect the expansion and erosion of tidal flats are still unclear. In this study, we analyzed all of the available Landsat TM/ETM+ /OLI imagery from the period 1996 to 2018 using the Google Earth Engine (GEE) cloud computing platform to obtain annual maps of coastal tidal flats of YRE at 30 m spatial resolution. We chose three sample tidal flats where severe Spartina alterniflora (S. alterniflora) invasion, reclamation, and control areas existed to explore the joint impact of plant invasion and reclamation on tidal flats. We also point out the main driving factor of tidal flat expansion of each island in YRE by multiple linear regression. Our results suggest that the tidal flats of YRE had obvious expansion from 1996 to 2018, and the speed of expansion is getting slower because of the decreasing deposits in the Yangtze River. Invasive S. alterniflora is effective at promoting silting, and tidal flats with S. alterniflora invasion expanded 2.54 times faster than the control group. Chongming and Hengsha Islands were mainly affected by sediment concentration, while Changxing and Jiuduansha Islands were affected by reclamation and S. alterniflora invasion, respectively. The results could be used to support coastal zone management and biodiversity conservation of the YRE.
... The more perfect the development of the tidal creeks, the more prominent it was. Some researchers (Callaway and Josselyn 1992;Rosso et al. 2006) also confirmed that S. alterniflora could invade the interior of the wetland along the tidal creek network in San Francisco Bay. The growth of other surrounding vegetation was limited by the strong germination ability, adaptability of S. alterniflora seeds and the strong underground roots of S. alterniflora. ...
For providing a better understanding of the quantitative relationship between typical wetland vegetation and their tidal creek habitats in the Yellow River Estuary, the tidal creeks and three wetland vegetation types of Spartina alterniflora, Phragmites australis and Suaeda salsa were selected to analyze their distribution characteristics and explore the correlation between their spatial distributions within the different areas in the study. Authors applied the methods of regional statistical analysis, proximity analysis and spatial autocorrelation analysis to quantifying the spatial distribution characteristics of vegetation and tidal creeks and their spatial interaction as well. The results showed that 86.87% of S. alterniflora was distributed in the salt-fresh water interaction zones along the Yellow River. S. alterniflora occupied more space around the tidal creeks. P. australis and S. salsa were only closely related to low-order tidal creeks, but the curvature of their surrounding tidal creeks was higher than that of S. alterniflora. The three types of vegetation in the Tidal Creek Buffer Zone (TCBZ) had spatial agglomeration in their habitats. Among of three vegetation types, S. alterniflora had the closest relationships with tidal creeks. This study has an important theoretical and practical significance for the management and restoration of related wetland ecosystems.
... Of the biotic communities, the plant community has become more similar to the community in reference sites over the 8-y period than any other community in the restoration sites. Spartina alterniflora is driving this pattern, which is not surprising given that this species is regarded as the main ecosystem engineer of salt marshes along the east coast of North America (Byers et al., 2006;Altieri et al., 2007;Lambrinos and Bando, 2008) and is a prominent invasive species in salt marshes on the Pacific coast of North America (Callaway and Josselyn, 1992) and in China (Bo et al., 2009). Spartina alterniflora readily colonizes bare area on mudflats via rhizomes and seedlings if the area is high enough in the tidal frame (Redfield, 1972;Feist and Simenstad, 2000), and helps to bind sediments and maintain sediment accumulation at high rates. ...
... Therefore, the habitats of native plants, birds and benthic animals are affected by S. alterniflora, and biodiversity is reduced [17,18]. In addition, the invasion of S. alterniflora impedes the development of local aquaculture and tourism and hinders water-based transportation [19,20]. The significant negative impacts of this species have far exceeded its ecological functions and economic benefits [12,21,22]. ...
Background:
Spartina alterniflora is an invasive plant on the coast of China that replaces native vegetation and has a serious negative impact on local ecosystems. Monitoring the spatial distribution of S. alterniflora and its changes over time can reveal its expansion mechanism, which is crucial for the management of coastal ecosystems. The purpose of this study was to map the distribution of S. alterniflora in Zhejiang Province from 1985 to 2015 using a time series of Landsat TM/OLI images and analyze the temporal and spatial patterns of expansion of this species.
Results:
After analyzing the distribution of coastal vegetation, the vegetation index was calculated based on Landsat images for 4 years (1985, 1995, 2005 and 2015). According to a threshold determined based on expert knowledge, the distribution of S. alterniflora in Zhejiang Province was extracted, and the temporal and spatial changes in the distribution of S. alterniflora were analyzed. The classification accuracy was 90.3%. S. alterniflora has expanded rapidly in recent decades after being introduced into southern Zhejiang. Between 1985 and 2015, S. alterniflora increased its area of distribution by 10,000 hm2, and it replaced native vegetation to become the most abundant halophyte in tidal flats. Overall, S. alterniflora expanded from south to north over the decades of the study, and the fastest expansion rate was 463.64 hm2/year, which occurred between 1995 and 2005. S. alterniflora was widely distributed in the tidal flats of bays and estuaries and expanded outward as sediment accumulated.
Conclusions:
This study reveals the changes over time in S. alterniflora cover in Zhejiang and can contribute to the control and management of this invasive plant.
... It has been introduced deliberately or accidentally to the coasts of England, France, and other countries or regions [10][11][12][13]. It has become a problematic species as it can out-compete native plants, cause estuary channel siltation, and change ecosystem structure [10,[14][15][16]. ...
Genetic variation and population structure may reflect important information for invasion success of exotic plant species and thus help improve management of invasive plants. Spartina alterniflora is an invasive plant that is a major threat to the economy and environment of the coastal regions in China. We analyzed the genetic structure and diversity of six populations of S. alterniflora differing in invasion histories in Guangxi, China. A total of 176 individuals from the six populations produced 348 AFLP fragments. The average heterozygosity was significantly lower than in the native population. And genetic bottlenecks were also detected in most populations. Standardized FST statistics (Φpt = 0.015) and AMOVA results indicated weak genetic differentiation. Genetic admixture and obviously isolation by distance indicated populations in Guangxi come from a pre-admixed population by a single introduction. High phenotypic variations of S. alterniflora in Guangxi influenced by soil salinity and temperature might be an important reason for the successful invasion.
Species invasion in salt marsh wetlands is known to disturb the balance of biotic and abiotic ecosystems (e.g., changing material exchange cycles and community structure). However, its influence on the morphological evolution of salt marshes is not yet understood in depth. This study investigates the long-term temporal and spatial distributions of an invasive plant (Spartina alterniflora) and its morphological characteristics in the Yangtze Estuary by remote sensing imagery interpretation, tidal creek extraction, regional statistical analysis, and proximity analysis. The invaded site shows an area of Spartina alterniflora with a 35-fold increase from the start to the end of its initiation phase; it is the second biggest species in the study area. It is found that species invasion not only limited the expansion of native pioneer vegetation but also changed bio-geomorphic feedback loops. With the influence of plant invasion, median tidal creek lengths decreased and the median tidal creek sinuosity ratio remained stable, between 1.06 and 1.07 in the subarea. The method used here is adaptable to other salt marshes. The findings from this study can provide practical guidance for the restoration of native salt marshes in the estuary and thus control the spread of invasive species.
Spartina alterniflora Loisel., which is native to the Atlantic coast of North America and the Gulf Coast of Mexico, is a perennial grass that occurs on intertidal mudflats and in estuarine salt marshes. The distribution of this species is currently increasing worldwide owing to intentional introductions for conservation and management purposes (e.g., reclaiming tidal flats and protecting coastal areas) and/or via unintentional introduction pathways, including escape from managed sites. Spartina alterniflora affects native intertidal ecosystems and coastal industries by forming dense communities in areas where it has encroached. The species was first detected in Japan in 2008, in the vicinity of the Umeda River estuary in Toyohashi City, Aichi Prefecture. The species was also detected in Kumamoto Prefecture in 2010. Due to the threat that S. alterniflora may pose to intertidal ecosystems and coastal industries, all Spartina species, including S. alterniflora, were listed as invasive alien species by the Japanese government in 2014. Here, we summarise the morphological and ecological characteristics of S. alterniflora and report on a new population detected in an estuarine salt marsh in Shimonoseki City, Yamaguchi Prefecture, in 2020.
Smooth cordgrass ( Spartina alterniflora Loisel.), an aggressive non-native species worldwide, colonized tidal flats on the west coast of Korea in two regions differing in tidal amplitude between 1990–2004. By the time of our study in 2015, expansion had occurred both clonally and through formation of new patches, providing an opportunity to determine intertidal range, which is a key component of understanding the threat posed by S. alterniflora through competition with native halophytes or transformation of unstructured mudflat. At Ganghwa (5.69 m tidal range), S. alterniflora ranged from 3.52 to 1.34 m above Mean Sea Level (MSL). At Jindo (2.02 m tidal range), S. alterniflora ranged from 1.57 to -0.18 m relative to MSL. Thus, a wider absolute intertidal range was occupied by S. alterniflora at the megatidal vs mesotidal region, but the lower limit of S. alterniflora did not extend below MSL under megatidal conditions, a pattern that now appears to emerge consistently in both the native and introduced range. In both study regions, S. alterniflora occurred at the same elevations as other salt marsh plants, occupying an upper zone with Phragmites australis (non-native) and middle zone with several native species including Suaeda japonica . S. alterniflora occurred below native marsh vegetation at all sites, which would result in transformation of the extensive mudflats along the Korean coast.
This datasheet on Spartina alterniflora covers Identity, Overview, Distribution, Dispersal, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Prevention/Control, Further Information.
One of the biggest threats to the survival of many plant and animal species is the destruction or fragmentation of their natural habitats. The conservation of landscape connections, where animals, plants, and ecological processes can move freely from one habitat to another, is therefore an essential part of any new conservation or environmental protection plan. In practice, however, maintaining, creating, and protecting connectivity in our increasingly dissected world is a daunting challenge. This fascinating volume provides a synthesis on the current status and literature of connectivity conservation research and implementation. It shows the challenges involved in applying existing knowledge to real-world examples and highlights areas in need of further study. Containing contributions from leading scientists and practitioners, this topical and thought-provoking volume will be essential reading for graduate students, researchers, and practitioners working in conservation biology and natural resource management.
Biogeoscience is a rapidly growing interdisciplinary field that aims to bring together biological and geophysical processes. This book builds an enhanced understanding of ecosystems by focusing on the integrative connections between ecological processes and the geosphere, hydrosphere and atmosphere. Each chapter provides studies by researchers who have contributed to the biogeoscience synthesis, presenting the latest research on the relationships between ecological processes, such as conservation laws and heat and transport processes, and geophysical processes, such as hillslope, fluvial and aeolian geomorphology, and hydrology. Highlighting the value of biogeoscience as an approach to understand ecosystems, this is an ideal resource for researchers and students in both ecology and the physical sciences.
Spartina alterniflora as an alien invasive plant, poses a serious threat to the ecological functions of the coastal wetland of the Jiaozhou Bay. As of 2019, the distribution area of S. alterniflora in the Jiaozhou Bay has reached more than 500 hm2. For this reason, combined with field surveys, remote sensing monitoring of the invasion S. alterniflora in the Jiaozhou Bay has been carried out. To accurately identify S. alterniflora within the Jiaozhou Bay coastal wetland, we used a new method which is an implement of deep convolutional neural network, and by which we got a higher accuracy than the traditional method. Based on distribution of S. alterniflora extracted by the proposed method, the temporal and spatial distribution characteristics of S. alterniflora were analyzed. And then combined with environmental factors, the invasion mechanism of S. alterniflora in the Jiaozhou Bay was analyzed in detail. From the monitoring results, it can be seen that S. alterniflora in Jiaozhou Bay is mainly distributed in the beaches near the Yanghe River Estuary and its southern side, the Dagu River Estuary and the Nügukou. Spartina alterniflora first broke out near the Yanghe River Estuary and gradually spread to the tidal flats near the Nügukou. The Dagu River Estuary is dominated by S. anglica, whose area has not changed much over the years, and a small amount of S. alterniflora has invaded later.
Ecological theory provides powerful tools to improve our ability to restore wetlands. Disturbance, its size, intensity, and duration, is important to predict how quickly the system is restored once the (anthropogenic) stressors are removed. Life history traits such as generation time, propagule production, and modes of dispersal are needed to understand which species will colonize a site and which will need assistance. Succession, how plant and animal communities change over time, offers concepts such as facilitation, mutualistic interactions, beneficial mycorrhizae, and bioaugmentation with microbes that can accelerate restoration. Concepts describing the individualistic nature of succession include assembly rules and the environmental sieve whereby physical constraints, flooding, salinity, and other factors can predict which species will colonize and then persist. Life history traits and succession theory are also formidable tools to identify potential invaders as well as a community's susceptibility to invasion. An understanding of ecosystem development, energy flow and nutrient cycling, especially N, is needed to set realistic expectations for rates at which wetland-dependent functions are restored.
Salt marshes are highly dynamic and important ecosystems that dampen impacts of coastal storms and are an integral part of tidal wetland systems, which sequester half of all global marine carbon. They are now being threatened due to sea-level rise, decreased sediment influx, and human encroachment. This book provides a comprehensive review of the latest salt marsh science, investigating their functions and how they are responding to stresses through formation of salt pannes and pools, headward erosion of tidal creeks, marsh-edge erosion, ice-fracturing, and ice-rafted sedimentation. Written by experts in marsh ecology, coastal geomorphology, wetland biology, estuarine hydrodynamics, and coastal sedimentation, it provides a multidisciplinary summary of recent advancements in our knowledge of salt marshes. The future of wetlands and potential deterioration of salt marshes is also considered, providing a go-to reference for graduate students and researchers studying these coastal systems, as well as marsh managers and restoration scientists.
Background
The Yancheng coastal natural wetlands (YCNR) are well-preserved silty tidal flat wetlands in China. Due to the severe invasion of Spartina alterniflora , the native ecosystem has undergone great changes. The successful invasion of S. alterniflora reduced the biodiversity of the YCNR, changed the structure and function of the local ecosystem, and eventually led to the degradation of the ecosystem and the loss of ecosystem function and service. Fully understanding the impact of an alien species invasion on YCNR succession is an important prerequisite for protecting and restoring the wetlands.
Methods
In this study, remote sensing, GIS technology, and a cellular-automaton Markov model were used to simulate the natural succession process of native ecosystems without being affected by alien species. By comparing the landscape of the YCNR with the model simulation results, we gained a better understanding of how alien species affect native landscape-scale ecosystems.
Results
During the natural succession of the coastal native wetland ecosystem in the YCNR, the pioneer species S. alterniflora occupied the mudflats and expanded seaward. The whole area expanded and moved seaward with an average annual movement of 58.23 m. Phragmites australis seemed to dominate the competition with S. salsa communities, and the area gradually expanded with an average annual movement of 39.89 m. The invasion of S. alterniflora changed the native ecosystem’s spatial succession process, causing the S. salsa ecosystem to be stressed by ecosystems on the side of the sea ( S. alterniflora ) and that of land ( P. australis ). The area of the seaward-expanding P. australis ecosystem has been declining. Under a reasonable protected area policy, human activities have enhanced the succession rate of the P. australis ecosystem and have had a small impact on the ecological spatial succession of S. salsa and S. alterniflora .
Invasive Spartina alterniflora (S. alterniflora), a native riparian species in the U.S. Gulf of Mexico, has led to serious degradation to the ecosystem and biodiversity as well as economic losses since it was introduced to China in 1979. Although multi-temporal remote sensing offers unique capability to monitor S. alterniflora over large areas and long time periods, three major hurdle exist: (1) in the coastal zone where S. alterniflora occupies, frequent cloud coverage reduces the number of available images that can be used; (2) prominent spectral variations exist within the S. alterniflora due to phonological variations; (3) poor spectral separability between S. alterniflora and its co-dominant native species is often presented in the territories where S. alterniflora intruded in. To articulate these questions, we proposed a new pixel-based phenological feature composite method (Ppf-CM) based on Google Earth Engine. The Ppf-CM method was brainstormed to battle the aforementioned three hurdles as the basic unit for extracting phonological feature is individual pixel in lieu of an entire image scene. With the Ppf-CM-derived phenological feature as inputs, we took a step further to investigate the performance of the latest deep learning method as opposed to that of the conventional support vector machine (SVM); Lastly, we strive to understand how S. alterniflora has changed its spatial distribution in the Beibu Gulf of China from 1995 to 2017. As a result, we found (1) the developed Ppf-CM method can mitigate the phonological variation and augment the spectral separability between S. alterniflora and the background species regardless of the significant cloud coverage in the study area; (2) deep learning, compared to SVM, presented better potentials for incorporating the new phenological features generated from the Ppf-CM method; and (3) for the first time, we discovered a S. alterniflora invasion outbreak occurred during 1996–2001.
Biological invasion poses a huge threat to ecological security. Spartina alterniflora was introduced into China in 1979, and its arrival corresponded with negative effects on native ecosystems. To explore geographical variation of its expansion rate in coastal China, we selected 43 S. alterniflora sites from Tianjin Coastal New Area to Beihai. The area expansion rate, expansion rate paralleling and vertical to the shoreline were analysed based on Landsat images and field survey in 2015. Simple Ocean Data Assimilation (SODA) and climate data were collected to statistically analyse the influential factors of expansion rate. Results showed that significant difference of S. alterniflora area expansion rate among different latitude zones (P < 0.01), increasing from 6.08% at southern (21°N–23°N) to 19.87% in Bohai Bay (37°N–39°N) along latitude gradient. There was a significant difference in expansion rate vertical to shoreline in different latitude zones (P < 0.01) with the largest occurring in Bohai Bay (256 m/yr, 37°N–39°N), and showed an decreasing tendency gradually from north to south. No significant difference and latitudinal clines in expansion rate paralleling to shoreline were observed. Expansion rate had significant negative correlation with mean seawater temperature, the lowest seawater temperature, current zonal velocity and meridional velocity and presented a reducing trend as these biotic factors increased; however, they were not significantly correlated with the highest seawater temperature and mean seawater salinity. We identified significant correlations between expansion rate and annual mean temperature, the lowest temperature in January and annual precipitation, but there was little correlation with annual diurnal difference in temperature and the highest temperature in July. The rapid expansion rate in high-latitude China demonstrated a higher risk of potential invasion in the north; dynamic monitoring and control management should be established as soon as possible.
Giant reed, Arundo donax L., is one of the greatest threats to riparian ecosystems of Mediterranean-type climate regions, including California. Forming extensive monotypic stands, A. donax increases the risks of flooding and fire, uses prodigious amounts of water, and reduces habitat value for wildlife. Urban and agricultural development adjacent to riparian ecosystems may contribute to its invasion success. The main hypothesis of my dissertation is that the current abundance of nutrients, water, light, and fire in riparian ecosystems of Mediterranean-type climate promotes A. donax invasion. A two-year field experiment in a riparian ecosystem on the Santa Clara River in California showed that A. donax produced greater biomass than native species under
high soil moisture, light, and nutrient levels, and its biomas-s in monoculture was much
greater than most species and treatment levels. However, results suggest that high
resource levels and this new plant functional group in these riparian ecosystems, rather
than superior resource competition, promote A. donax’s competitive exclusion of native
riparian species. Analysis of the influence of nutrient enrichment from residential and
agricultural land use types on A. donax infestation throughout several coastal watersheds
in Southern California revealed that floodplains with enriched soil NO3-N supported A.
donax infestations whereas sites with lower N levels did not. Unlike the native red
willow (Salix laevigata Bebb.), A. donax may take advantage of anthropogenically
enriched N (and K) levels in riparian ecosystems. Regarding fire, A. donax began
regrowth from rhizomes immediately after being burned in October 2003 along the Santa
Clara River whereas native riparian plants remained dormant for several months, and A.
donax grew 3–4 times faster than native riparian plants. A year after the fire, A. donax
dominated these burned areas (99% relative cover and a 24% increase in relative cover
compared to pre-fire conditions). Arundo donax infestations appear to create an invasive
plant-fire regime. These results help elucidate the optimal conditions for A. donax
invasion of riparian ecosystems, which in turn can help prioritize control strategies and
revegetation of riparian ecosystems.
In New England salt marshes, Spartina alterniflora dominates the low-marsh habitat, which is covered daily by tides. The high-marsh habitat (not flooded daily) is dominated on its seaward border by S. patens, and on its terrestrial border by Juncus gerardi. While high-marsh perennials appear to be restricted to the high-marsh habitat by harsh physical conditions in the low-marsh habitat, S. alterniflora appears to be excluded from the high-marsh habitat by the high-marsh perennials. Throughout the high marsh, Distichlis spicata and Salicornia europaea are associated with phycial disturbance, in the form of mats of dead plant material (wrack) rafted by tides onto the marsh, which is most severe in the spring and early summer, and which decreases with increasing marsh elevation. D. spicata and S. alterniflora are most tolerant of wrack burial. Short-term disturbance increases the relative abundance of these species in the community. Longer lasting disturbance events kill the underlying vegetation, leaving bare patches throughout the high marsh. D. spicata rapidly colonizes these patches with runners; S. alterniflora and Sa. europaea recruit by seed. Over time these early colonizers are overgrown and displaced in high-marsh patches by S. patens and J. gerardi, which grow slowly, as dense turfs of roots, rhizomes, and tillers.-from Authors
Rates of recolonization in natural open patches in a Massachusetts salt marsh were monitored for 3yr. Vegetative expansion of Spartina alterniflora at c12cm yr-1, accounted for most of the recolonization of open patches, although some colonization of annual Salicornia spp. occurred from seeds. Salinity and sulfide and ammonium concentrations were measured in pore water samples from depths of 2-7cm and 10-15cm of soil. Comparison of the concentrations from disturbed and undisturbed plots in the marsh did not show significant differences, indicating that none of the edaphic conditions measured would be more inhibitory to plant growth in disturbed plots. Rate at which small open patches become recolonized is thus primarily controlled by proximity of Spartina alterniflora and its capacity for vegetative expansion. -from Author
Seed predation can be an important determinant of plant success, but has received little attention in wetland plant communities. Here, we examine the role of flower and seed predators in limiting the seed production of the dominant perennial plants in a salt marsh plant community. Of the four perennial investigated, direct ovule loss to consumers ranged from 51 to 80%, resulting in seed set reductions ranging from 50% to over 20-fold. Most losses were due to generalist grazing by the grasshopper, Conocephalus spartinae. More species-specific losses were inflicted by planthoppers, and microlepidopteran and dipteran larval seed parasites.
Insect abundance and consumer pressure on flowers and seeds increased over the early summer, peaked in the middle of July, and declined through August, and this temporal pattern was reflected in the natural consumer damage incurred by each of the marsh perennials. Juncus gerardi flowers earlier than other marsh perennials and largely escapes heavy consumer losses. Spartina patens and Distichlis spicata flower in the middle of the summer during the peak consumer activity and incur extremely heavy seed losses. Spartina alterniflora flowers late in the summer as consumer pressure is subsiding, which appears to minimize its seed loss. In addition to destroying seeds directly, consumers also markedly reduce the frequency and affect the timing of sexual expression in these plants. In particular, predation drastically reduces the frequency of male flowers, which could lead to pollen limitation of seed set.
Intense flower and seed predation on these marsh perennials may be an important determinant of the success of marsh plant populations as well as a potent selective force on their flowering phenologies and reproductive effort.
Patterns of survival and spatial arrangement of tillers of Spartina alterniflora were examined in natural and in artificially produced bare areas, and in pure stands of adult S. alterniflora in a New England salt marsh. Seedling growth and survival were high in naturally occurring bare patches and in artificial patches, whether created by continual clipping of adult plants to ground level throughout the growing season or by providing bare substrate after removal of adult plants. Seedling growth and survivorship increased with increasing size of bare area. S. alterniflora seedlings were also common in areas dominated by adult plants, but no seedlings survived a whole first growing season under the mature canopy, probably because of competition from adult plants.
In large bare areas, S. alterniflora seedlings grew non-directionally, reaching heights of 0.5 m, and producing as many as 36 tillers in one growing season. Examination of leaf area ratios suggested that the production of tillers increased photosynthetic capacity in seedlings with several tillers in contrast to seedlings without tillers. Thus, seedlings can apparently tiller and colonize free space radially without a loss of photosynthetic capacity.
These results suggest that while seedling success is generally limited by adult plants in monocultures of S. alterniflora, in disturbed spaces seedling success is high and results in a rapid non-directional proliferation of sexually generated clones that ultimately preclude the successful invasion of future seedlings.
The San Francisco Bay estuary has been rapidly modified by human activity. Diking and filling of most of its wetlands have eliminated habitats for fish and waterfowl; the introduction of exotic species has transformed the composition of its aquatic communities; reduction of freshwater inflow by more than half has changed the dynamics of its plant and animal communities; and wastes have contaminated its sediments and organisms. Continued disposal of toxic wastes, the probable further reduction in freshwater inflow, and the possible synergy between the two provide the potential for further alteration of the estuary's water quality and biotic communities.
Twenty years ago, an international conference on The Genetics of Colonizing Species was held in Asilomar. The proceedings of the conference were published in the next year (Baker and Stebbins 1965). The plant materials that were discussed then were mainly weeds.* This would seem to be a restriction but it is a fact that most colonizing plants are weeds. In North America, except for the sea shores, the moraines in front of receding glaciers, and the recolonization of devastated areas around Mount St. Helens, there are few opportunities for introduced plants to take part in plant succession. Otherwise, the disturbance in the natural system that almost always seems to be necessary for plant invaders to be successful is caused by human activities.
California is a land of unusual biotic diversity. It comprises a wide range of indigenous ecosystems including a diversity of forest, woodland, scrub, and grassland types as well as numerous kinds of aquatic systems. Making up these systems are 5720 species of vascular plants (Raven and Axelrod 1978), over 200 mammal species (Ingles 1965; Williams 1979), about 28,000 insect species (Powell and Hogue 1979), 525 bird species (Small 1974), 129 amphibian and reptile species (Jennings 1983), and 132 inland fish species (Moyle 1976; Shapovalov et al. 1981).
Measurements of soil oxygen diffusion rates along transects crossing the ecotone between Spartina and Salicornia were made during the summer. They indicated slight decreases with increasing depth, but there were no significant differences between readings taken in the Spartina zone and those in the Salicornia zone. These results, together with the observation of iron oxides surrounding Salicornia roots in the marsh soil, indicate that soil aeration is not an important factor affecting the distribution of Spartina and Salicornia about the MHW ecotone. Experiments in which Salicornia and Spartina plants were exposed to artificial tides of different heights indicated that the growth of Salicornia seedlings and older plants is reduced by 30-40% by `tides' only 8 cm higher than in the control and lasting only 1/12 of the daylight period. The higher `tides' also inhibited re-rooting and the production of new branches. Growth of Spartina plants was not significantly affected. In the light of measured differences in ground level between the Spartina and Salicornia zones, this indicates that inhibition of growth resulting from tidal immersion may be an important factor checking the seaward advance of Salicornia and tending to exclude it from the Spartina zone.
Shorebirds, particularly Redshank (Tringa totanus), fed more on areas recently cleared from intertidal cord-grass flats (Spartina) than on areas cleared 3-4 years before, and much more than within untreated swards of this cord-grass. Recently cleared areas did not always hold highest absolute densities of invertebrates important as bird foods, but these areas remained wetter during low tide and were more open in character than other zones. The long-term efficacy of control of Spartina with a single dose of 'Dalapon' has yet to be established.
(1) Five harvest methods (peak standing crop, and the methods of Milner and Hughes (1968), Smalley (1959), Valiela, Teal & Sass (1975), and Wiegert & Evans (1964) were used to estimate the net aerial primary production (NAPP) of angiosperm species in coastal salt marshes of eastern U.S.A. (2) Differences as great as ten-fold were found between the five methods. All methods except that of Wiegert & Evans underestimated NAPP. Wiegert & Evans' method may have overestimated NAPP. (3) The ranking of species by NAPP, which may be used as a measure of their importance to the estuarine system, varied between methods. (4) It was concluded that the morphology of the species, the location, and the general environmental conditions affect the results of any single method and that these factors must be considered before selecting a particular harvest method. In addition, future work should assess the precision of the methodologies.
Results of a 2-yr evaluation of aboveground production of 7 plant species commonly found in Louisiana's coastal marshes show a generally higher level of production compared to other studies. In 5 of the 7 species significant growth occurred throughout the year. Calculated annual production in grams per square metre for each species was; Distichlis spicata--3237; Juncus roemerianus--3416; Phragmites communis--2318; Sagittaria falcata--1501; Spartina alterniflora--2658; Spartina cynosuroids-1355; and Spartina patens--6043. Sampling variability, expressed as the ratio of the standard error to the mean x 100, averaged between 8 and 18 different species. Instantaneous loss rates (mg x g^(-1) x day^(-1)) of dead vegetation from the marsh, averaged over the year, ranged from 4.7 for P. communis to 25.2 for S. falcata.
On the shores of San Pablo Bay distinct zones are occupied by nearly monospecific communities of Spartina foliosa (in the mid-littoral zone) and Salicornia virginica (in the upper littoral zone). Measurements of above-ground and below-ground standing crop, and seasonal production were made in 1972 along two transects crossing the ecotone between the two species at Mean High Water Level: one on Mare Island and one on the Petaluma River. The above-ground standing crop and production of Spartina declined in all respects as the ecotone was approached on both transects. The above-ground standing crop and production of Salicornia also decreased toward the ecotone, but at Mare Island Salicornia was more productive per unit biomass or per stem in the Spartina zone than in the Salicornia zone. Living rhizomes and roots of Salicornia were found primarily in the upper 15 cm of soil. Living rhizomes and roots of Spartina were distributed throughout the soil profile but tended to be absent from the upper 15 cm in the Salicornia zone. Total standing crop and production, including both species, decreased to a minimum at the middle of the ecotone. It appears that the zonation is dependent on physical factors and physiological responses rather than on interspecific competitive effects.
(1) The number of dunlin, Calidris alpina alpina (L.), wintering in the British Isles has decreased by almost half since 1973-74, much of the decrease occurring before 1977-78. A similar decrease seems to have occurred in the other main wintering areas in Holland and France between 1973-74 and 1977-78. But since then, numbers in these two countries have not decreased whereas in Britain numbers declined by a further 77 000 by 1985-86. (2) The rate of decline since 1977-78 has varied between British estuaries, many showing no change in numbers. Dunlin numbers declined at the greatest rates in estuaries where cord grass, Spartina anglica C. E. Hubbard, has spread most over the intertidal flats where the birds feed. In estuaries where the extent of Spartina has not changed, numbers of dunlin have not declined significantly, except in some small estuaries in south Devon and in north Scotland. (3) The results suggest that most birds displaced from estuaries where Spartina has spread have not yet been able to re-establish themselves elsewhere in Britain or in some other countries within the wintering range of Calidris alpina. Nor have dunlin numbers increased in estuaries where Spartina has declined through natural die-back. The reasons for this, and the implications of the results as a whole for the conservation of dunlin, are discussed.
Rates of spread of Spartina anglica and associated accretion of sediment on sand and mud flats were measured by re-examining transects and a permanent quadrat that were set up 9 years earlier (1973) in the New River Estuary, Invercargill. Spread is slowest where the species nears its lower tidal limit, and where there is erosion of sediment. In recently colonised areas the maximum spread of vegetation is 5.3 m/a. Sediment accretion rates varied from 12 mm/a in dense swards on muddy substrate, to 3 mm/a on sand in areas of turbulent water. One area of erosion is reported.
Spartina was first planted in the Waihopai River Estuary in 1913 and has spread to cover 15% of the mudflats. Tidal inundation was observed to determine possible further spread. Landward spread appears to be limited by the presence of Leptocarpus similis. The seaward edge corresponds to the low neap-tide level which appears to be close to the level of most of the mudflat area. Future colonisation seems to depend on the relationship between the neap-tide minimum level and the level of the mudflats. Spartina emerges during daylight hours for 887 hr per annum (1973 data) at its lower limit. This value is much lower than periods for marshes in England and is probably the result of the Waihopai having clear estuarine waters.
Spartina plants have continuous gas spaces from the leaves to the tips of the roots. Oxygen values in the roots are as low as 3 per
cent and increase toward the stem. Carbon dioxide values are highest in the rhizome and decrease up the stem and toward the
root tips. Oxygen and carbon dioxide moved through the plants at equal rates for equal gradients, and these rates agree with
measurements made on plants in the marsh. Calculated oxygen and carbon dioxide fluxes for the observed gradients in the observed
gas spaces agreed with measured fluxes. We conclude that gases move in and out of Spartina roots by diffusion through uninterrupted gas spaces within the plant.
Much as Rachel Carson's "Silent Spring" was a call to action against the pesticides that were devastating bird populations, Charles S. Elton's classic "The Ecology of Invasions by Animals and Plants" sounded an early warning about an environmental catastrophe that has become all too familiar today-the invasion of nonnative species. From kudzu to zebra mussels to Asian long-horned beetles, nonnative species are colonizing new habitats around the world at an alarming rate thanks to accidental and intentional human intervention. One of the leading causes of extinctions of native animals and plants, invasive species also wreak severe economic havoc, causing $79 billion worth of damage in the United States alone. Elton explains the devastating effects that invasive species can have on local ecosystems in clear, concise language and with numerous examples. The first book on invasion biology, and still the most cited, Elton's masterpiece provides an accessible, engaging introduction to one of the most important environmental crises of our time. Charles S. Elton was one of the founders of ecology, who also established and led Oxford University's Bureau of Animal Population. His work has influenced generations of ecologists and zoologists, and his publications remain central to the literature in modern biology. "History has caught up with Charles Elton's foresight, and "The Ecology of Invasions" can now be seen as one of the central scientific books of our century."-David Quammen, from the Foreword to "Killer Algae: The True Tale of a Biological Invasion"
Descriptions of, and keys to the three species of Spartina in New Zealand: S. alterniflora, S. anglica, S. × townsendii, are presented with distribution maps for each. The introduction, history, planting, and spread of each species is discussed as is its ecology, especially in relation to past and future potential for spread. In some places the problems caused by its spread are virtually insurmountable. With renewed appreciation of estuarine wetlands in their natural states, planting of any species of Spartina around the coast of New Zealand should not be allowed to take place. Suitable control and eradication measures need to be developed where Spartina is already present.
This is the first report of Spartina anglica in China ever presented in an international symposium. China introduced this neophyte mainly in 1963 from England for the purpose of land reclamation. A contrast of geographical environments of England, with special reference to southeast England, and China is made. There are more than 100 locations of S. anglica in about 90 cities and counties of every coastal province, from 40°53′N to 21°30′N. The total area distribution approximates 33,000 ha. Jiangsu ranks highest with 18,700-22,000 ha, Zhejiang second with 6,900-8,400, Shandong 3,000, Fujian 1,000, Hebei 970, Guangxi 153 and Liaoning 70. East China contains about four-fifths of the total hectarage, north China much less and south China the least. Problems of geographical distribution are discussed and preliminary explanations are suggested.
We employed sequential aerial photographs from 1939 to 1981 to document establishment and exponential spread ofSpartina patens on Cox Island the only recorded Oregon locality for this east coast species.Spartina patens, growing in distinctive circular patches, now occupies more than 3000 m2 with no diminished expansion rate. Eight marsh communities are aggregated into four generalized marsh types: Low Marsh, Middle
Marsh, High Marsh, and Transition Marsh.Spartina patens invades theDeschampsia caespitosa-Scirpus maritimus community, the most open (7.7 percent “bare ground”) of the Middle Marsh communities.Spartina patch elevation ranges from 1.83 to 2.05 m above MLLW comparable to its indigenous east coast tidal position. Proximate expansion
of individual circular patches is by clonal growth. The role of seed and vegetative propagule dispersal in establishment of
new colonies has not been determined. Once established,S. patens in Oregon performs comparably to its performance in Delaware and New England as shown by its general growth form, average
above-ground live biomass of 329 gdw m2, above-ground dead biomass of 411 gdw m2, and a below-ground to above-ground biomass ratio of 4.80.
One hundred years ago the striped bassMorone saxatilis was introduced in the San Francisco Bay estuarine system from the east coast of the United States. It was part of our national
policy at the time to transplant all potentially useful species everywhere else. The policy was facilitated by completion
of the transcontinental railroad in 1869. As a result, the present ichthyofauna of the San Francisco Bay area is largely alien.
Introduction of eastern oystersCrassostrea virginica resulted in the inadvertent introduction of many species of invertebrates. Identification of these introduced species was
not realized as a problem until recently, and no one knows how many exotic species there are. In other parts of the world
there are examples of similar introductions, e.g.Crepidula fornicata andRhithropanopeus harrisi in Europe. Although it is now the policy to frown upon and prohibit introductions, they cannot be prevented and the process
still continues, as witnessed by the examples ofElminus modestus in Europe andPalaemon macrodactylus in California. In the USA the recently developed idea of “mitigation,” the artificial replacement of disturbed or destroyed
areas by development of quasi-natural areas in compensation, has been accompanied, at the hands of inexperienced practitioners,
by potentially dangerous introductions of exotic species. The assumption, for example, that cordgrass(Spartina) should be equally beneficial everywhere in the world has led to the disrupting introduction of potentially hybridizing species
in New Zealand and aggressive immigrants in Oregon marshes. This situation calls for more sophisticated understanding of the
role of introduced species in natural aquatic ecosystems, and a higher degree of competence in systematic biology.
Spartina alterniflora Loisel, produces large quantities of viable seed, particularly when stands are vigorous and relatively young. Excellent germination
occurred when seeds were harvested as near the shattering stage as possible, stored in burlap sheets at 2–3 C for 1 month,
and submerged in estuarine or sea water at 2–3 C until seeding the following spring. Direct seeding from April until early
June is an effective method of establishing new stands ofS. alterniflora on dredge spoil in protected areas. The elevational range over which seedlings can be expected to survive is limited to the
upper 20–50% of that occupied by natural stands in a given area. Complete cover is achieved the first growing season and the
above-ground standing crop produced from seed in one growing season can exceed that produced from transplants and may approach
that of long-established marshes.
Increases in nutrient supply convert swards of the short form of Spartina alterniflora into plants tending to resemble the tall form, in biomass/m2 and in general morphology. Competition for light is probably responsible for the vertically elongate, widely dispersed growth habit of tall form. Provision of added nutrients led to larger δ13C values, probably by the incorporation of heavier carbon from the internal air spaces of S. alterniflora during high tide, when exchange of gases with the atmosphere is prevented. The amount of interstitial water replenished at each tide is greater in areas supporting tall-form vegetation than where short form grows. There are also greater densities of mussels near creek banks, and their feeding and defecation lead to larger accumulations of particulate matter and nutrients where tall form is found. The amount of nitrogen delivered by algal nitrogen fixation does not differ greatly under the two forms. Seedling establishment usually produces tall-form plants, and a highe...
How important are individual species in controlling ecosystem properties? Many studies of ecosystem-level dynamics are conducted with little reference to the influences of the individual species within ecosystems. In some cases this dis-regard is explicit, and it is argued that whole-system functional properties are better indicators of ecosystem status than is any aspect of species biology (O’Neill et al. 1977). This point of view has been deplored but not unambiguously disproved (cf. Foin and Jain 1977; Mcintosh 1980).
Asks 1) what attributes of communities make them more likely to be invaded? and 2) what attributes of individual species make them more likely to be successful invaders? Data are drawn from 1) the large-scale, but unintentional introduction of alien plant species into British plant communities, and 2) the recorded attempts to establish introduced insects for the biological control of weeds. -from Author
The term “colonizer” has come to mean different things to different biologists. In a general sense all species are colonizers, as they all must become established in sites in which to grow and reproduce. Agriculturalists have equated colonizers with undesirable and, in many cases, nonnative species that affect agroeco-systems detrimentally by reducing the growth and yield of the desired species. In this agronomic sense the terms colonizers, “weeds,” and often “aliens,” are synonymous. Theoretical ecologists usually think of colonizers as those species whose disseminules travel relatively long distances, and arrive in unoccupied or presumably incompletely occupied habitats where they subsequently interact with other species present or become locally extinct [e.g., the island biogeographic model of Mac Arthur and Wilson (1967)].
Typescript. Thesis (M.A.)--San Francisco State University, 1990. Includes bibliographical references.
Typescript (photocopy). Thesis (Ph. D.)--Iowa State College, 1953. Includes bibliographical references.
Thesis (Ph. D.)--Dept. of Biological Sciences, Stanford University. Bibliography: l. 91-92.
Thesis (M.A.)--San Francisco State University. Includes bibliographical references (leaves 72-74).
The aerenchyma (air-space) tissue in the wetland macrophyte Spartina alterniflora conveys sufficient oxygen to roots for predominately aerobic respiration in moderately, but not highly, reduced substrates. Continuously flooded plants survive by respiring anaerobically, although growth is decreased. Two metabolic adaptations to flooding are displayed in this species, depending on the degree of soil reduction.
A review of structure in several North Carolina salt marsh plants Ecology of Halophytes History, land-forms, and vegetation of the estuary
- C E Anderson
- B F Atwater
- S G Conrad
- N Dowden
- C W Hedel
- R L Macdonald
- And W Savage
ANDERSON, C. E. 1974. A review of structure in several North Carolina salt marsh plants, p. 307-344. In R.J. Reimold and W. H. Queen (eds.), Ecology of Halophytes. Academic Press, New York. ATWATER, B. F., S. G. CONRAD,]. N. DOWDEN, C. W. HEDEL, R. L. MACDONALD, AND W. SAVAGE. 1979. History, land-forms, and vegetation of the estuary's tidal marshes, p.
The introduction ofSpartina alternifiora in south San Francisco Bay Geographical distribution of Spartina an-glica C. E. Hubbard in China
- J C Callaway
- C H Chung
CALLAWAY, J. C. 1990. The introduction ofSpartina alternifiora in south San Francisco Bay. M.A. Thesis, San Francisco State University, San Francisco. 50 p. CHUNG, C. H. 1983. Geographical distribution of Spartina an-glica C. E. Hubbard in China. Bulletin of Marine Science 33: 753-758.
Distribution and environmental control of productivity and growth form of Spartina alterniflora (Loi-sel.), p. 127-142 The Hague Spartina (Gramineae) in Northern California: Distribution and taxonomic notes
- M R Smart
- D Spicher
- M And
- Josselyn
SMART, M. R. 1982. Distribution and environmental control of productivity and growth form of Spartina alterniflora (Loi-sel.), p. 127-142. In D. N. Sen and K. S. Rajpuroit (eds.), Contributions to the Ecology of Halophytes. Dr. W. Junk, The Hague. SPICHER, D. AND M. JOSSELYN. 1985. Spartina (Gramineae) in Northern California: Distribution and taxonomic notes. Ma-droiio 32:158-167.
The Ecology of San Francisco Bay Tidal Marshes: A Community Profile. U.S. Fish and Wildlife Ser-vice, Division of Biological Services Rates of spread of Spartina anglica and sediment accretion in the New River Estuary
- M N Josselyn
JOSSELYN, M. N. ! 983. The Ecology of San Francisco Bay Tidal Marshes: A Community Profile. U.S. Fish and Wildlife Ser-vice, Division of Biological Services, Washington, D.C. 102 p. FWS/OBS-83/23. LEE, W. G. AND T. R. PARTRIDGE. 1983. Rates of spread of Spartina anglica and sediment accretion in the New River Estuary, Invercargill, New Zealand. New Zealand Journal of Botany 21:231-236.
Introduced cordgrass, Spartina alterniflora Loi-sel. in salt marshes and tidelands ofWiIlapa Bay, Washington. U.S. Fish and Wildlife Service, Willapa National Wildlife Ref-uge
- K Sayce
SAYCE, K. 1988. Introduced cordgrass, Spartina alterniflora Loi-sel. in salt marshes and tidelands ofWiIlapa Bay, Washington. U.S. Fish and Wildlife Service, Willapa National Wildlife Ref-uge, Ilwaco, Washington. 70 p. FWSI-87058(TS).
Com-puter program. SIgma Soft, Placentla, Cahfornla. RANWELL, D. S. 1967. World resources of Spartina townsendii (sensu lato) and economic use of Spartina marshland
- R A Pimental
- D A~d ]
- Smith
- ~
- B~os~at
PIMENTAL, R. A. A~D]. D. SMITH. 1~85. B~OS~AT I. Com-puter program. SIgma Soft, Placentla, Cahfornla. RANWELL, D. S. 1967. World resources of Spartina townsendii (sensu lato) and economic use of Spartina marshland. Journal of Applied Ecology 4:239-256.
Introduction and spread of cordgrass (Spartina) into the Pacific Northwest
- R E Frenkel
FRENKEL, R. E. 1987. Introduction and spread of cordgrass (Spartina) into the Pacific Northwest. Northwest Environmental Journal 3:152-154.