Ammophila Arenaria (Marram Grass) Management Information

Ammophila arenaria (marram grass) Management Information

Prepared by the IUCN SSC Invasive Species Specialist Group

1.0 Introduction...... Page 1 2.0 Monitoring...... Page 1 3.0 Physical Control...... Page 1 4.0 Chemical Control...... Page 2 5.0 Integrated Management...... Page 3 6.0 References...... Page 4

1.0 Introduction Native to Europe, Ammophila arenaria, or marram grass, has been widely distributed to many countries to stabilise and establish sand dunes for forestry plantings, property protection and erosion control (Russo et al., 1988; Dixon et al., 2004; Hilton, 2006). In some areas it has become invasive, out-competing and displacing native species and altering the coastal topography (Russo et al., 1988; Hilton et al., 2005). Due to its extensive underground rhizome network A. arenaria is a difficult species to control, with eradication continuing to prove challenging to land managers (Pickart, 1997). Two key efforts are essential to effective control of A. arenaria: thatch removal and resprout control (Hyland & Hollorand\, undated).

2.0 Monitoring Biological monitoring of A. arenaria documents long-term spread and loss of native habitat through estimates of stand density and size supported by photo documentation (Russo et al., 1988). As part of an ongoing control program, pre and continual post treatment monitoring is a vital element. Pre treatment monitoring involves measuring the increase in stand size at four points located at the windward, leeward, and lateral boundaries while post treatment monitoring involves monthly surveys of the foredune and upper beach area for new invasions (Russo et al., 1988).

3.0 Physical Control Manual removal by pulling or digging with a shovel followed by burning has been shown to be effective but also hugely cost and labour intensive (Pickart, 1997). Successful control of A. arenaria at a remote site (Lanphere-Christensen Dunes Preserve in Humboldt Bay, California) required 1,858 person-hours / acre to dig, pile and burn the plants in addition to the 1,093 person- hours / acre required for transportation to the site at a total cost of about US$ 34,674 / acre (Pickart, 1997). Other reported costs of manual removal range widely between US$ 36,600 / ha 1

(Peterson, 2004; in Hyland & Holloran, undated) to US$ 86,703 / ha (Pickart & Sawyer, 1998; in Hyland & Holloran, undated).

In addition to the initial labour intensive dig due to the high density and biomass of existing A. arenaria, continual resprouting over two seasons required 8 return visits during the first season and 7 the second season (Pickart, 1997). While eradication was largely achieved by the end of the second season, follow up work was still required for more remote stands.

An advantage of manual removal is that it allows the selective retention of relic native plants which can flourish following the removal of A. arenaria, saving on the costs of revegetation (Pickart, 1997). However, manual removal of A. arenara may also lead to the subsequent invasion of other exotic species such as Carpobrotus sp., and as such continued monitoring is necessary (Russo et al., 1988).

Mechanical removal using heavy equipment has also been used to control A. arenaria in Oregon, USA, often in conjunction with chemical or manual removal techniques (Pickart, 1997). Excavation and burial to a theoretical depth of 3 feet by a bulldozer (D-8 Caterpillar) was used by the U.S Forest Service to treat 45 acres of A. arenaria over 3 years. Burial depths however were inconsistent and often less than 3 feet, limiting the effectiveness of this treatment (Pickart, 1997). Moderate resprouting of A. arenaria occurred and required manual follow-up, as not enough of the plants were exposed for herbicide use to be effective (Pickart, 1997).

At the nearby Coos Bay Shorelands, 50 acres of A. arenaria were treated by using a bulldozer (again a D-8 Caterpillar) with a wing ripper, to “subsoil” or “rip” rhizomes 3 feet below the surface; rhizomes were then able to be easily pulled manually at a later date (Pickart, 1997). This appeared to be a successful method, however a number of different treatments were trialled on the same area prior to mechanical control; the effects of these being impossible to separate (Pickart, 1997).

With sufficient quality control heavy machinery use is more cost and labour effective than manual removal over a large area, however it is only suitable for easily accessible and flat land, and is more detrimental to invertebrate native plant communities (Pickart, 1997). The costs of heavy machinery can vary depending on the machinery and operators available (Pickart, 1997) and can range from US$13,246 / ha (Peterson, 2004; in Hyland & Holloran, undated) to US$ 38,769 / ha (Jane Rodgers, pers. comm.; in Hyland & Holloran, undated).

4.0 Chemical Control Glyphosate based herbicides have shown some success when used to control A. arenaria with effectiveness dependant on consistency and thoroughness of application (Pickart, 1997). Roundup was found to be effective when tested extensively in California (Aptekar, pers comm.; in Pickart, 1997) as well as on the Chatham Islands (Moore & Davis, 2004). However, the surfactant used in Roundup at the time of Pickart’s report included polyethoxylated tallowarnine and raised concerns of groundwater contamination, leading to a preference for Rodeo; a glyphosate based herbicide without an included surfactant (Pickart, 1997). While the surfactant in Roundup has since been reformulated (McColly, pers comm.; in Pickart, 1997), Morris &

Davis mainly used the haloxyfop based herbicide Gallant after initial Roundup application as it is grass-specific and does not affect non-target broadleaf species (Morris & Davis, 2004). Spraying of salt-water was attempted as a chemical control for A. arenaria in Oregon (Pickart, 1997). Three 24 hr applications of 12 inches of salt-water were made on a 25 acre stand in order to raise the soil salinity to at least 2 % to a depth of 3 feet (the soil salinity tolerance of A. arenaria being 1 – 1.5 %) (Pickart, 1997). However, while some browning occurred, the salt- water did not penetrate below the top 5 inches of soil and was deemed unsuccessful (Pickart, 1997). Furthermore, salt-water is likely to have negative effects on desirable plant species and beneficial soil microbes (Pickart, 1997). Chemical treatment of A. arenaria is likely to be among the most cost-effective method of those used to date, however they have biological impacts and may be politically unacceptable in a given area or for particular agencies (Pickart, 1997). Chemical control is also unfeasible for treating small amounts of resprouting, as not enough of the plant is exposed; this requires additional manual control at an additional cost if total eradication is desired (Pickart, 1997). Dead biomass also needs to be manually cleared for the regeneration of native habitat (Pickart, 1997; Moore & Davis, 2004). Additionally, when native plants are present, selective spraying may be difficult or impossible (Pickart, 1997).

5.0 Integrated Management Prescribed burning was trialled as a less costly alternative to manual removal (Hyland & Holloran, undated). By itself, fire is not an effective treatment since it stimulates regrowth (Pickart & Sawyer, 1998; in Hyland & Holloran, undated). However, under some conditions, it can reduce the time required to conduct subsequent treatments (Miller, 1998; in Hyland & Holloran, undated). In particular, reducing thatch and stimulating regrowth creates ideal conditions for effective and efficient herbicide treatment: a greater proportion of the chemical is delivered to receptive plant tissues that will then translocate it to the rhizomes (Hylland & Holloran, undated).

Given certain conditions such as easy site access, in-house expertise with prescribed burns and herbicide use, and remnant native plant communities or seedbanks to facilitate regeneration, the combination of burning and herbicide use can provide a cheap alternative to manual removal with Hyland and Holloran estimating costs as low as US$4000 / ha.

6.0 References Dixon, P., Hilton, M., & Bannister, P. (2004). Desmoschoenus spiralis displacement by Ammophila arenaria: the role of drought. New Zealand Journal of Ecology, 28(2), 207-213. Hilton, M.J. (2006). The loss of New Zealand’s active dunes and the spread of marram grass (Ammophila arenaria). New Zealand Geographer, 62, 105–120. Hilton, M.J., Duncan, M., & Jul, A. (2005). Processes of Ammophila arenaria (marram grass) invasion and indigenous species displacement, Stewart Island, New Zealand. Journal of Coastal Research, 21(1), 175-185. Hyland, T., & Holloran, P. (undated). Controlling European beachgrass (Ammophila arenaria) using prescribed burns and herbicide. Retrieved 1 November, 2009 from UC Santa Cruz website: http://ic.ucsc.edu/~kholl/envs160/holloran&hyland.pdf Moore, P., & Davis, A. (2004). Marram grass Ammophila arenaria removal and dune restoration to enhance nesting habitat of Chatham Island oystercatcher Haematopus chathamensis, Chatham Islands, New Zealand. Conservation Evidence, 1, 8-9. Pickart, A.J. (1997). Control of European Beachgrass (Ammophila arenaria) on the West Coast of the United States. California Exotic Pest Plant Council, The Nature Conservancy Lanphere-Christensen Dunes Preserve Arcata, CA 95521. Russo, M., Pickart, A., Morse, L., & Young, R. (1988). Element Stewardship Abstract for Ammophila arenaria European Beachgrass. Retrieved 1 November, 2009 from iMapInvasives website: http://www.imapinvasives.org/GIST/ESA/esapages/documnts/ammoare.pdf