Beyond the Marram Grass: 1966

The principal aim of this paper is to show that marram grass is not an invasive alien in South Africa although it affects the dune dynamics as a useful pioneer species in the dune successional process. The historical perspective of marram introduction as a dune stabiliser and the studies and conclusions reached from our European Union funded project, INVASS, in the 1990s and early 2000s is presented. Although these studies showed that marram was non-invasive, this was not clearly carried through to the authorities, and the use of the grass as a dune stabiliser was limited without a special permit. This prompted a survey of the current situation of marram on dune sites in the Eastern Cape. Along with earlier (1980s) data on the dunes, 69 relevés with 66 species abundance from sites along the Eastern Cape shoreline were assembled. These data were analysed with Detrended Correspondence Analysis to show the relationships of the samples (relevés) and species in a 2-dimensional scatter diagram. The survey showed that there are four dune sites where marram grass is no longer present, due to either marram being out of its climatic range, erosion of sand under storm conditions which made the habitat unsuitable, or in one case where marram simply disappeared. Marram often remains in other sites where three to five dune pioneer species were recorded. On some dunes, although marram is the most abundant dune pioneer, it is never dominant in the dune environment but has a presence of as much as 75% at any site. The eight pioneer species are widely dispersed on the DCA scatter diagram, while the shrub species characterising the Coastal Scrub are tightly clustered, showing that all the pioneer dune communities behave similarly in the dune successional series. The conclusion from these studies is that marram grass does not always persist in the dune systems. If marram does persist, it does not compete and behaves identically to the indigenous species as a dune pioneer. These studies show that marram grass is a non-invasive species that can be successfully used in dune stabilisation on Cape dunes.

Habitat-modifying plants engineer biogeomorphic landscapes through self-reinforcing interactions with their physical environment, or so-called ‘biogeomorphic feedbacks’. Nevertheless, benefits can vary across a biogeomorphic landscape gradient and between plant-life stages. For instance, European marram grass forms dunes by trapping sediments which triggers plant growth, in turn promoting sediment trapping. Yet, by increasing dune height and vegetation cover, marram grass mitigates sediment dynamics, inhibiting sediment-growth feedbacks, which ultimately leads to its demise. However, little is known about how dune formation affects the growth and survival of marram grass at different life stages. Therefore, we performed a two-level field experiment testing the effect of position on marram grass across the biogeomorphological dune gradient (beach, foredune, backdune) on (i) the establishment success of juvenile transplants and (ii) the resilience of mature plants to disturbance by above-ground biomass removal, over one growing season. Although juvenile transplants grew similarly well across the dune gradient, significantly fewer beach transplants (67%) survived compared to the foredune- and backdune transplants. Conversely, survival of mature disturbed marram grass (100%) was unaffected, yet recovery was highest at the beach and significantly decreased across the dune gradient. We could link these opposing responses to habitat modification. In heavily modified dune habitats sediment stabilization aided juvenile establishment, whereas the high sediment dynamics of unmodified beaches facilitated adult resilience indicating dune formation invokes a trade-off between establishment and resilience. Our findings highlight the importance of assessing life stage-dependent differences in environmental requirements of habitat-modifying plants to understand population dynamics and landscape-forming processes.

Journal of the Society of Dyers and ColouristsVolume 36, Issue 5 p. 145-145 Correspondence Marram Grass, Marram Grass 5, Ludgage Cirus E.C.4.Search for more papers by this author Marram Grass, Marram Grass 5, Ludgage Cirus E.C.4.Search for more papers by this author First published: May 1920 https://doi.org/10.1111/j.1478-4408.1920.tb01084.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume36, Issue5May 1920Pages 145-145 RelatedInformation

The functional composition of dune nematode communities is structured by both biogeographic region and the local marram grass environment

The present study (1) describes the rates and patterns of Ammophila arenaria (marram grass) invasion in a large transgressive dune system (Mason Bay) and on a prograding foredune-ridge barrier (Doughboy Bay), Stewart Island, New Zealand; (2) examines the impact of Ammophila on dune morphology and indigenous dune biota; and (3) assesses the significance of geomorphic processes in accounting for the patterns observed. Processes of Ammophila invasion are interpreted from evidence of landform development and vegetation change; field observations and survey of dune landforms and dune vegetation; the aerial photographic record and historic accounts of the local botany. The area dominated by Ammophila in the Mason Bay study area has increased from 1.4 ha in 1958, to 17.8 ha in 1978, to 74.9 ha in 1998; a 5,204 percent increase. Ammophila invasion of active dune systems in the study areas is clearly associated with dune forming processes—shadow dune development; migration of long-walled parabolic dunes; stoss face blowout development; and barrier progradation. The primary mechanism of native species displacement appears to be burial rather than competition for nutrients. Ammophila traps sand and builds dunes at rates that may exceed the threshold of tolerance of local native species. Desmoschoenus spiralis, the dominant indigenous foredune species, cannot co-exist with Ammophila in the active dune systems investigated.

New Zealand coastal dune systems have been invaded by Marram grass (Ammophila arenaria) over the last 50 years. This is thought to have had a significant effect on the ecosystem biodiversity and coastal geomorphology. Care needs to be taken if eradication is to be undertaken that the dune systems are not unstabilised and more problems are caused. Marram grass was originally planted as a sandbinder and has created massive foredunes on exposed coasts Cooper [1], Wiedemann and Pickart [2] and Elser [3] that has major implications for the geomorphic development of transgressive dune systems. Little work has been done to study the impact of these foredunes on the development of downwind dunes. Initial work is being undertaken to model the flow over a particular coastal dune system at Mason Bay, Stewart Island, New Zealand with a typical marram covered foredune with a transgressive parabolic dune downwind. Previous work, Hart et al [4], has compared a two-dimensional slice of the topography as of 2003 (marram) and 1958 (pre-marram) numerically to understand the pattern of wind on the foredune and more importantly in the deflation zone. This paper compares Computational Fluid Dynamic (CFD) modelling of the existing topography with experimental wind measurements. Emphasis will be on the validation of the numerical model data. The protocol needed in taking account of the roughness of the different surface coverings over the surface will be discussed. Validation of two-dimensional transects through the dune complex will inform the resulting three-dimensional model. A protocol for modelling in the future will be ascertained in terms of roughness values to use dependent on vegetation present, mesh size, turbulence model to use and domain size.

Trophic interactions are often deduced from body size differences, assuming that predators prefer prey smaller than themselves because larger prey are more difficult to subdue. This has mainly been confirmed in aquatic ecosystems, but rarely in terrestrial ecosystems, especially in arthropods. Our goal was to validate whether body size ratios can predict trophic interactions in a terrestrial, plant-associated arthropod community and whether predator hunting strategy and prey taxonomy could explain additional variation. We conducted feeding trials with arthropods from marram grass in coastal dunes to test whether two individuals, of the same or different species, would predate each other. From the trial results, we constructed one of the most complete, empirically derived food webs for terrestrial arthropods associated with a single plant species. We contrasted this empirical food web with a theoretical web based on body size ratios, activity period, microhabitat, and expert knowledge. In our feeding trials, predator-prey interactions were indeed largely size-based. Moreover, the theoretical and empirically based food webs converged well for both predator and prey species. However, predator hunting strategy, and especially prey taxonomy improved predictions of predation. Well-defended taxa, such as hard-bodied beetles, were less frequently consumed than expected based on their body size. For instance, a beetle of average size (measuring 4 mm) is 38% less vulnerable than another average arthropod with the same length. Body size ratios predict trophic interactions among plant-associated arthropods fairly well. However, traits such as hunting strategy and anti-predator defences can explain why certain trophic interactions do not adhere to size-based rules. Feeding trials can generate insights into multiple traits underlying real-life trophic interactions among arthropods.

Leymus racemosus (Lam.) Tzvelev subsp. sabulosus (M. Bieb.) Tzvelev (mammoth wildrye) and Ammophila arenaria (L.) Link (marram grass) are perennial, psammophilous species which dominate sand dunes due to their biological characteristics. Their communities have an important role in the formation of the natural vegetation cover of coastal sand strips along the Bulgarian Black Sea Coast. This study provides the first systematic analysis of tolerance of L. racemosus subsp. sabulosus and A. arenaria to sea water immersion along the Bulgarian Black Sea Coast. It aims to determine effects of flooding stress on whole plants and how long rhizomes can remain viable in sea water. Two experiments establish that decomposition of leaves of immersed plants starts from the 7th day. A growth of stems and root sprouts is observed on the same day. There are no visible decompositions of stems, roots and rhizomes till the end of the experiment (20th day). Rhizomes from the investigated species are able to regenerate after 30 days of submergence and bud viability appears to be enhanced slightly by sea water. L. racemosus subsp. sabulosus shows higher bud viability than A. arenaria. The possible negative consequences of flooding to L. racemosus and A. arenaria communities based on experimental results, hydrodynamical modelling, detailed topography, bathymetry surveys and detailed GIS mapping on Panorama Beach are discussed.

UAV-imaging to model growth response of marram grass to sand burial: Implications for coastal dune development

In about half of the Dutch coastal dunes, the former wet slacks have dried during the last 100 years. The purpose of this study was to find the causes of drying. A fall in watertable was the major cause. it was sometimes due to coastal erosion, sometimes to increase of evapotranspiration because of an increase in vegetation, especially the planting of coniferous trees, extraction of groundwater for mains of drinking water supply or drainage by ditches. Although slacks are drying out with a fall in watertable, the blowing out of sand to the watertable can produce new wet slacks. It is the combination of fall in watertable and the almost complete prevention of blow-outs, by planting of marram grass and other plants of trees, which make drying out a continuous process. In some dried areas, surface water from elsewhere is infiltrated for later recovery in behalf of drinking water supply. In such areas, dried slacks are flooded or channels have been dug by which open water has been produced on a considerable scale. Other dried slacks in such areas sometimes get wet again. Because of the unnatural fluctuations in watertable and the large supply of nutrients, the vegetation of such slacks is of a ruderal character and atypical of dunes.

In biogeomorphic landscapes, plant traits can steer landscape development through plant‐mediated feedback interactions. Interspecific differences in clonal expansion strategy can therefore lead to the emergence of different landscape organisations. Yet, whether landscape‐forming plants adopt different clonal expansion strategies depending on their physical environment remains to be tested. Here, we use a field survey and a complementary mesocosm approach to investigate whether sediment deposition affects the clonal expansion strategy employed by dune‐building marram grass individuals. Our results reveal a consistent shift in expansion pattern from more clumped, Brownian‐like, movement in sediment‐poor conditions, to patchier, Lévy‐like, movement under high sediment supply rates. Additional model simulations illustrate that the sediment‐dependent shift in movement strategies induces a shift in optimisation of the cost–benefit relation between landscape engineering (i.e. dune formation) and expansion. Plasticity in expansion strategy may therefore allow landscape‐forming plants to optimise their engineering ability depending on their physical landscape.

Extending the observational record to provide new insights into invasive alien species in a coastal dune environment of New Zealand

Marram grass (Ammophila arenaria) and sea-wheat grass (Thinopyrum junceiforme) have been introduced to Australia and New Zealand. This study examines the morphology of incipient foredunes and established foredunes associated with these species at two sites, Mason Bay in southern New Zealand, and the Younghusband Peninsula in South Australia. Both species invaded the existing foredunes very rapidly. In both cases the antecedent topography comprised relatively sparsely vegetated, irregular foredunes. Invasion resulted in continuous, regular, evenly vegetated foredunes. At Mason Bay a massive foredune has formed since 1958, in conjunction with Ammophila. Thinopyrum has formed an incipient foredune, with a ramp or terrace morphology, along the Younghusband Peninsula, South Australia. In both cases gaps in the former foredune have been closed and the indigenous foredune vegetation has been displaced. Both species may decrease the frequency and severity of blowout development. They are likely to be resilient to aeolian processes of sedimentation compared with dunes formed by indigenous species. Ammophila survives burial, is tolerant of drought and is resistant to erosion associated with storm surge and high waves. Thinopyrum is very tolerant of salinity. These species may adversely affect the long-term development of coastal barriers by inhibiting transgressive dune development.

Coastal dunes, shaped by natural processes, particularly aeolian sediment transport driven by onshore winds, are dynamic environments where vegetation plays a pivotal role in trapping sediments, enabling dunes to reach substantial heights. However, the biomechanical traits of aboveground dune vegetation have received limited attention, impeding precise modeling in coastal engineering. Understanding dune erosion and accretion is essential for enhancing coastal resilience and the integration as ecosystem-based coastal protection measures. Notably, prior research has primarily focused on salt marshes and seagrass (e.g. Keimer et al. 2023), neglecting more detailed modeling of dune vegetation, often employing simplified methods like live vegetation (Figlus et al. 2014; Silva et al. 2016) or wooden dowels (Kobayashi et al. 2013; Bryant et al. 2019). The hypothesis tested for the first time here is that geographic expositions and seasonal growth stages can be quantified for marram grass (Ammophila arenaria), and that in turn, these vegetation characteristics will inform laboratory studies involving the interaction of waves, flexible vegetation and eroding dunes.

Evolution of foredune texture following dynamic restoration, Doughboy Bay, Stewart Island, New Zealand