No evidence for interspecific interactions between plants in the first stage of succession on coastal dunes in subarctic Quebec, Canada

1997 ◽  
Vol 75 (6) ◽  
pp. 902-915 ◽  
Author(s):  
Gilles Houle
Keyword(s):  
Plant Biomass ◽  
Interspecific Interactions ◽  
Regional Climate ◽  
Salt Spray ◽  
Coastal Dunes ◽  
Growing Season ◽  
Coastal Dune ◽  
Dune System ◽  
Abiotic Conditions ◽  
Herbaceous Perennials

Coastal dunes are very dynamic systems, particularly where the coast is rising as a result of isostatic rebound. In those environments, succession proceeds from plants highly tolerant to sand accumulation, salt spray, and low nutrient availability to less disturbance-tolerant and stress-tolerant, more nutrient-demanding, and supposedly more competitive species. In the subarctic, the regional climate exacerbates the stresses imposed by local abiotic conditions on the dunes. I hypothesized that facilitation would be particularly significant on the foredune of subarctic coastal dune systems because of intense stresses (local and regional) and frequent disturbance in the form of sand deposition. Belowground and aboveground plant biomass was sampled at three different periods during the 1990 growing season along transects perpendicular to the shoreline on a coastal dune system in subarctic Quebec (Canada). The three herbaceous perennials found on the foredune (Honckenya peploides, Elymus mollis, and Lathyrus japonicus) were segregated in time during the growing season and in space along the topographical gradient. The biomass of Honckenya, the first species encountered as one progresses from the upper part of the beach towards the foredune ridge, was not correlated to substrate physicochemistry. However, the biomass of Elymus and that of Lathyrus, the next two species to appear along the flank of the foredune, were related to pH, Mg, Na, and Cl (negatively), and to P and Ca (positively). These results suggest variable linkages between substrate physicochemistry and plant species along the foredune, possibly in relation to species-specific tolerance for abiotic conditions and requirements for substrate resources or to microscale influence of the plants themselves on substrate physicochemistry. Removal experiments carried out over 2 years revealed only one significant unidirectional interaction between these three species along the topographical gradient, and little plant control over abiotic variables (e.g., soil temperature, wind velocity, and photosynthetically active radiation). Early primary succession on subarctic coastal dunes (and elsewhere) appears to be under the control of strong limiting abiotic conditions. As plants slowly gain more control over the physical environment, interspecific interactions (positive and negative) may become more significant. Key words: Elymus mollis, facilitation, Honckenya peploides, inhibition, Lathyrus japonicus, removal experiment, succession, tolerance.

Environmental filters and seedling recruitment on a coastal dune in subarctic Quebec (Canada)

1996 ◽  
Vol 74 (9) ◽  
pp. 1507-1513 ◽  
Author(s):  
Gilles Houle
Keyword(s):  
Seed Germination ◽  
Spatial Pattern ◽  
Seedling Establishment ◽  
Seedling Recruitment ◽  
Salt Spray ◽  
Spatial Segregation ◽  
Coastal Dune ◽  
Seedling Mortality ◽  
Environmental Filters ◽  
Dune System

One important factor that often determines the presence of a plant species on a site is propagule availability. Afterwards, abiotic and biotic factors act as a series of filters operating sequentially from the seed to the adult stage, determining the pattern of recruitment. By comparing the spatial pattern of emerging seedlings to those of seed availability and of surviving seedlings, one can determine the relative importance of the environmental filters acting on the seed germination and the seedling establishment phases. On a coastal dune system in subarctic Quebec (Canada), sand accumulation, salt spray, and substrate physicochemistry, all affecting microsite quality for seeds and seedlings, vary along a short topographical gradient. My goal was to determine whether or not conditions changing along this gradient differentially affect the initial stages of population recruitment of two perennial herbaceous species for which adults are segregated along the gradient: Honckenya peploides and Elymus mollis. The spatial pattern of seeds in the seed bank and that of emerging seedlings were not related to one another for either Honckenya or Elymus. However, patterns of surviving seedlings were spatially correlated with those of emerging seedlings. Seed and seedling mortality were not density dependent; they were both spatially variable, although not clinal. These results suggest that the environmental filters acting on the germination stage are those that determine the spatial patterns of recruitment. Spatial segregation along the flank of the foredune between adults of the two species studied thus seems to be maintained in part (and maybe reinforced) by low seed mobility, or low seed retention, and the availability of suitable microsites for seed germination. Population progression towards the upper beach seems to depend mostly on seedling establishment for Honckenya but on clonal growth for Elymus. Keywords: Elymus mollis, Honckenya peploides, Hudson Bay, partial Mantel test, spatial segregation, Whapmagoostui-Kuujjuaraapik.

Records of climate changes and anthropogenic actions over dune fields in historical times

2020 ◽  
Author(s):  
Mihaela Tudor ◽  
Ana Ramos-Pereira ◽  
Joana Gaspar de Freitas
Keyword(s):  
Climatic Variability ◽  
Coastal Dunes ◽  
Coastal Dune ◽  
Environmental Data ◽  
Dune System ◽  
Climatic Fluctuations ◽  
Dune Systems ◽  
Sand Drift ◽  
Aeolian Activity ◽  
Historical Times

<p>Coastal dunes are very complex systems and very sensitive to climatic variability and human actions. In Portugal, coastal dune fields have undergone major changes over historical times. The aim of the paper is focused on the coastal dune systems evolution over the last five centuries, natural and man induced (namely by deforestation and afforestation) and their transformation under the present global changes (sea level rise and coastal storms). The analysis of historical records and environmental data using a set of proxies recorded over the last 1,000 yrs, show intense aeolian activity and sand drift episodes during Little Age Period, causing serious problems for human settlements and agriculture. Coastal society have responded to the wind-blown sands fixing the dunes through afforestation. The process is well documented in the historical sources and many management measures, including abundant legislation, projects and reports were carried out by Portuguese authorities to avoid sand incursion inland.  According to the main report of the General Forest Administration, in the final of 18th century, was estimated an area of about 72 000 ha of free aeolian sands in need of afforestation. Thus, along Portuguese coastline, the dunes experienced a period of stability during the 20th century, due to planting of grasses and pine forest. This paper examines the pathways of the transgressive dune fields of the Central Western Portuguese coast, over various stages of coastal evolution. Mapping the morphological features between Mondego river mouth and Nazaré, using a combination of satellite images, aerial photographs and Lidar data we identified distinct phases of aeolian activity and landforms modification that were associated to climatic fluctuations. This coastal dune system is composed by a succession of different aeolian phases, including a littoral foredune, which lies inland with a complexity of morphologies with transverse and crescentic ridges, and also parabolic dunes. The results show that the dunes building and sand migration inland appears to be linked to the conditions of predominantly negative winter North Atlantic Oscillation index (NAOi), driven by climatic variability during Holocene/Antrhopocene. The consistency of intense sand drift episodes with abrupt cold events during Little Age Period, drastically reduced the area occupied by vegetation, causing changes in aeolian sedimentary processes. Thus, it seems that coastal dunes evolution over the past centuries have been controlled by the two-way interactions between natural conditions and human activities, shaping the Portuguese coastline. Placing historical evidence in a geographical perspective, we hope to fill the gaps in coastal zone dynamics, providing new insights of the human-landscape relationships to predict the future response of the coastal dune systems to human pressure and climate change.<br>Key-words: coastal dunes evolution, geomorphological features, sand drift, anthropogenic impacts, climatic fluctuation, Western Portugal.</p>

Coastal dunes - A nature based coastal protection element exposed to exacerbated anthropogenic stress

2021 ◽  
Author(s):  
Björn Mehrtens ◽  
Viktoria Kosmalla ◽  
Oliver Lojek ◽  
David Schürenkamp ◽  
Nils Goseberg
Keyword(s):  
Vertical Wall ◽  
Coastal Dunes ◽  
High Energy ◽  
Coastal Dune ◽  
Water Levels ◽  
Flood Protection ◽  
Coastal Protection ◽  
Dune System ◽  
Sand Surface ◽  
Joint Research Project

<p>Natural coastal dunes covered by vegetation are an essential component on many sandy coastlines worldwide and often provide the only physical protection against flooding by dissipating wave energy and enhancing erosion resilience. However, sea level rise, changing and widely intensifying coastal wave climates and storm surges constitute severe exacerbated stresses, calling into question the perseverance of such unique coastal ecosystems as dunes and their protective functions taken for granted.</p><p>Here we investigate the extensive coastal dune system of St. Peter-Ording, a major tourist draw of the German North Sea within a marine high energy zone. Lining the coast along 15 km, extending up to 1.5 km in cross-shore direction it covers an area of 18 sqkm characterized by overgrown dunes separating the tidal foreshore from the topographically flat hinterland. Featuring a dedicated, Germany wide unique, coastal protection function sets it apart from other national coastal dune systems - potentially creating a role model for mitigating coastal squeeze related driving factors, further adding to its awe-inspiring landscape character.</p><p>Consequently, the joint-research project ''Sandküste St. Peter Ording'' examines whether the local flood protection dune “Maleens Knoll”, a 16.6 m high natural coastal dune stretching a roughly 1.2 km long gap in the sea-dike defense, will continue to offer adequate protection in the future. Current hypothesis is, that due to the overgrowth with non-endemic and invasive vegetation species, the natural dynamic and self-adaptation of the system is impaired and will not withstand projected changes in coastal drivers. Therefore, the long-term goal is to develop a variety of nature-friendly flood protection measures to reinforce the dune and reduce its probability of failure during an extreme storm surge.</p><p>Possible options comprise the installation of hybrid systems, combining the existing dune core with one of the following structures: 1) a vertical wall to gain more stability during erosion of the sand cover, 2) rock filling to increase wave dissipation and reduce wave reflection and erosion and 3) geotextiles to provide a temporary and more environmentally protection against runup. The built-in materials will be covered with sand, to mimic the original landform and yield its previous degree of freedom regarding topographic adaptation. Another approach is to strengthen the resistance of the sand surface against aeolian and fluvial erosion. Through a microbiological process based on calcium carbonate precipitation (MICP), the strength can be increased in a particularly environmentally friendly way that saves raw materials. Furthermore, adapted or additional planting with a site-typical vegetation can promote sand accumulation at the surface and thereby stabilize the dune.</p><p>Large-scale physical model experiments will be performed in a wave flume to investigate the protection potential of the dune. First, the natural dune condition will be recreated and tested under a combination of water levels and wave conditions to investigate current and future load cases. Based on the findings, a second series of experiments will be conducted to determine which engineering methods are most appropriate to reinforce the dune and ensure its coastal protection character and retain its naturalness at the same time.</p>

scholarly journals Nature-Based Solution along High-Energy Eroding Sandy Coasts: Preliminary Tests on the Reinstatement of Natural Dynamics in Reprofiled Coastal Dunes

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2518 ◽  
Author(s):  
Bruno Castelle ◽  
Quentin Laporte-Fauret ◽  
Vincent Marieu ◽  
Richard Michalet ◽  
David Rosebery ◽  
...  
Keyword(s):  
Large Scale ◽  
Coastal Dunes ◽  
High Energy ◽  
Coastal Dune ◽  
Coastal Hazards ◽  
Dune System ◽  
Bare Sand ◽  
Stage Of Development ◽  
Scale Experiment ◽  
Natural Dynamics

This paper describes a large-scale experiment designed to examine if reinstating natural processes in the coastal dune systems of Southwest France can be a relevant nature-based adaptation in chronically eroding sectors and a nature-based solution against coastal hazards, by maintaining the coastal dune ecological corridor. An experiment started in late 2017 on a 4-km-long stretch of coast at Truc Vert, where experimental notches were excavated and intensively monitored in the incipient and established foredunes. Preliminary results indicate that most of the excavated notches did not develop into blowout. Only the larger elongated notches subsequently excavated in the established foredune in 2018 showed evidence of development, acting as an effective conduit for aeolian landward transport into the dunes. All notches were found to have a statistically significant impact on vegetation dynamics downwind, even those that did not develop. The area of bare sand landward and within the elongated notches notably increased implying a loss of vegetation cover during this first stage of development. Observations of a nearby coastal dune system that has been in free evolution over the last 40 years also indicate that, although the dune migrated inland by more than 100 m, it is now mostly made of bare sand. Further work is required to explore if and how dunes maintained as dynamic systems can become an efficient nature-based solution along this eroding coastline.

Morphological Differences in Lignotubers of Eucalyptus intermedia R.T. Bak. And E. signata F. Muell. Associated With Different Stages of Podzol Development on Coastal Dunes, Cooloola, Queensland

1987 ◽  
Vol 35 (3) ◽  
pp. 301 ◽  
Author(s):  
J Walker ◽  
CH Thompson ◽  
CJ Lacey
Keyword(s):  
Water Status ◽  
Salt Spray ◽  
Soil Nutrient ◽  
Coastal Dunes ◽  
Nutrient Status ◽  
Fire Regimes ◽  
Nutrient Supply ◽  
Dune System ◽  
Factors Affecting ◽  
Coastal Margin

The sandmass at Cooloola comprises a series of overlapping aeolian dune systems that extend in age from the present back more than 100 000 years. Podzols are the dominant soils, forming a sequence from rudimentary through to giant forms, according to age. The lignotuber morphology of Eucalyptus signata and E. intermedia was examined within each dune system across the chronosequence, at sites in which most factors affecting plant growth (available soil water status, drainage, light, temperature, fire regimes, exposure to wind and/or salt spray) other than a declining soil nutrient supply were similar. Three lignotuber morphologies were identified: (1) a single-stemmed (SS) form; (2) a multi-stemmed (MS) form with stems originating from a lignotuber only slightly larger than a main stem; and (3) a multi-stemmed plate-like form (MSP) with individual stems separated and growing from a plate-like lignotuber. Multi-stemmed forms of the two eucalypts occur along the coastal margin and on the most nutrient- poor dunes; at all other sites single-stemmed forms are dominant. The most nutrient-poor site had only MS and MSP forms, whilst in sheltered areas the coastal margin had SS individuals. We conclude that in the Cooloola sandmass the development of multi-stemmed forms in both E. signata and E. intermedia may be induced by a variety of factors, including very low nutrient status, but the multi-stemmed plate-like form of E. intermedia is most likely a response to an exceptionally low nutrient supply.

scholarly journals Interannual Variation in Root Production in Grasslands Affected by Artificially Modified Amount of Rainfall

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Karel Fiala ◽  
Ivan Tůma ◽  
Petr Holub
Keyword(s):  
Interannual Variation ◽  
Plant Biomass ◽  
Growing Season ◽  
Lower Amount ◽  
Root Production ◽  
Climate Scenarios ◽  
Natural Rainfall ◽  
Plant Matter ◽  
Grassland Ecosystems ◽  
Below Ground

The effect of different amounts of rainfall on the below-ground plant biomass was studied in three grassland ecosystems. Responses of the lowland (dryFestucagrassland), highland (wetCirsiumgrassland), and mountain (Nardusgrassland) grasslands were studied during five years (2006–2010). A field experiment based on rainout shelters and gravity irrigation simulated three climate scenarios: rainfall reduced by 50% (dry), rainfall increased by 50% (wet), and the natural rainfall of the current growing season (ambient). The interannual variation in root increment and total below-ground biomass reflected the experimentally manipulated amount of precipitation and also the amount of current rainfall of individual years. The effect of year on these below-ground parameters was found significant in all studied grasslands. In comparison with dryFestucagrassland, better adapted to drought, submontane wetCirsiumgrassland was more sensitive to the different water inputs forming rather lower amount of below-ground plant matter at reduced precipitation.

The “ReDune” index (Restoration of coastal Dunes Index) to assess the need and viability of coastal dune restoration

2015 ◽  
Vol 49 ◽  
pp. 178-187 ◽  
Author(s):  
Debora Lithgow ◽  
M. Luisa Martínez ◽  
Juan B. Gallego-Fernández
Keyword(s):  
Coastal Dunes ◽  
Coastal Dune ◽  
Dune Restoration

scholarly journals LATE BLOOMING OF PLANTS FROM NORTHERN NOVA SCOTIA: RESPONSES TO A MILD FALL AND WINTER

2011 ◽  
Vol 46 (2) ◽  
Author(s):  
David J. Garbary ◽  
Jonathan Ferrier ◽  
Barry R. Taylor
Keyword(s):  
Climate Change ◽  
Nova Scotia ◽  
Woody Plants ◽  
Regional Climate ◽  
Growing Season ◽  
Flowering Phenology ◽  
Flowering Date ◽  
Cornus Sericea ◽  
Allium Schoenoprasum ◽  
Herbaceous Dicots

Over 1400 flowering records of 135 species were recorded from over 125visits to more than 20 sites in Antigonish County, Nova Scotia from November2005 to January 2006, when the growing season is normally over. The speciesidentified were primarily herbaceous dicots; however, there were four speciesof woody plants (Cornus sericea, Spiraea latifolia, Symphoricarpos albusand Salix sp.) and one monocot (Allium schoenoprasum). The number ofspecies flowering declined linearly as fall progressed, as did the amountof flowering for each species. Nevertheless, over 40 species were still inflower in early December, and over 20 species flowered in January. Thefinal flowering date was 21 January, when ten species were found. Thiswork builds on a previous study in 2001, when 93 species were recordedin flower during November-December. In addition to the 30% increase inrecorded species in 2005, almost 50% of the species found in 2005 werenot recorded in 2001. This study provides an expanded baseline againstwhich changes in flowering phenology can be evaluated with respect tosubsequent regional climate change.Key Words: Antigonish, flowering, Nova Scotia, phenology, climate change

Geomophological and vulnerability analysis of a coastal delta under increased hydrological alteration over the past two centuries: Tana River delta, Kenya, East Africa.

2021 ◽  
Author(s):  
Peter Gitau ◽  
Stéphanie Duvail ◽  
Dirk Verschuren ◽  
Dominique Guillaud
Keyword(s):  
Sea Level Rise ◽  
East Africa ◽  
Sea Level ◽  
Coastal Dune ◽  
River Delta ◽  
River Channels ◽  
Dune System ◽  
The Past ◽  
Tana River ◽  
Coastal Dune System

<p>Coastal deltas worldwide are under risk of degradation due to the increasing impacts of sea-level rise, and continuous human alterations of river basin hydrology. This research highlights the geomorphological changes that have occurred within the Tana River delta in Kenya, an important deltaic ecosystem of high biodiversity value in East Africa.</p><p>The geomorphological features (river channels, floodplain, coastal dune system) and their evolution over the past two centuries were described. Aerial and satellite imagery was used to assess the magnitude and distribution of coastal changes from the 1960s to present.  Additionally, sediment cores recovered within the mangrove environment were analysed to establish the succession of sedimentation periods and patterns. Finally, we explored the response of the coastal processes of deposition and erosion under anthropogenic alterations of the hydrological system.</p><p>It was established that over the past two centuries Tana River has changed its main channel and outlet to the Indian Ocean on three occasions. A first river avulsion occurred in the 1860s, followed by a second avulsion in the late 1890s that was promoted by human interference through channel expansion and dyke construction. The third change in river course has occurred gradually over the past 20 years, amid human efforts to engineer the river channels.</p><p>From the sediment analysis and radiocarbon dating, it is ascertained that the lower deltaic region developed rapidly over the past ~180 years, facilitated by increased sedimentation from the main Tana River. On the other hand, analysis of the coastline changes indicate that there has been increased erosion of the coastal dune system and mangrove vegetation along the former river outlet, leading to rapid marine intrusion into local subsistence farming areas. By analysing the combined impacts of both natural river dynamics and human alteration we highlight how the integrity of the Tana River delta has increasingly become vulnerable under present sea level rise and continued upstream river alteration.</p>

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