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© Smooth cordgrass Classification (Spartina alterniflora ) Order Poales Family Poaceae Genus Spartina Species S. alterniflora Originated in the United States and Canada. (Loiseleur, 1807) Introduced into France in the 1800s, probably via maritime transport and ballast water. 1
Description
n A perennial grass, smooth surfaces n Upright leaves, grey-green in colour, flat or canaliculate, from 20 to 55 cm o s
long and 5 cm wide a m
n o T
The stalk is 60 cm to 1.2 metres tall and up to 2 cm wide at the base i D
n .
The panicle is 10 to 40 cm long, with numerous branches closely spaced J
n The seeds are elongated, between 0.5 and 1 cm long © n The rhizomes spread horizontally and produce stolons 2
Ecology and reproduction
n The plants can develop in different types of littoral wetlands (intertidal zones), e.g. salt meadows, mud flats (slikkes), lagoons n They can accept high salt concentrations and daily submersions n They can take root on different substrates, e.g. sand, silt, gravel e r è i
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They disperse via seeds produced by sexual reproduction i z r
n a
Clumps of plants propagate via the stolons L
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© Documentation 3 n Hudin S., Vahrameev P. et al. , 2010. Guide d’identification des plantes exotiques envahissant les milieux aquatiques et les berges du bassin Loire-Bretagne. Fédération des conservatoires d’espaces naturels, 45 pp. n Télabotanica . 2016. E-flora fact sheet for Spartina alterniflora .
http://www.tela-botanica.org/bdtfx-nn-65440-synthese
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a a r t © PNR Armorique. n h s r 2 i e e
c y t a h l a l y t Discussions with other stakeholders and partners 2 n A work group was established in 2010 to discuss site selection and work methods with researchers (European university institute for marine science), local managers of natural areas (Brest Métropole), the managing entities of the “Rade de Brest” SBMP, the National botanical conservatory in Brest, local groups (hunters in the maritime public domain) and environmental-protection groups (Bretagne Vivante), local governments, State services (Departmental territorial and maritime agency and the Maritime and littoral agency) and social reintegration associations.
Description of the interventions n A precise map of the sectors colonised by smooth cordgrass was drafted using . e photo-interpretation and contour GPS techniques. r è i l
n l The priority sectors for work were then defined on the basis of various criteria: i z r a
- type of substrate; L
. A
- emblematic sites, e.g. biologically diverse salt meadows, the presence of lax- flowered sea-lavender ( Limonium humile ); © - the importance for birds (reproduction and nesting sites, etc.); - the degree of colonisation and the residual surface of the salt meadows; 3 - site accessibility. A number of management methods were tested in parallel on the sites: - mowing; - uprooting; - scraping the surface; - digging containment trenches; - tarping. n e Equipment used: r è i l l i
- sickle; z r a L
- brush cutter; . A - spade; - garden fork; © - excavator; - agricultural tarp; 4 - hand shovel. n Scraping the surface is used in areas where the ground is harder or contains gravel, but only for surface areas of less than five square metres. n Containment trenches are a technique used for larger areas where the ground is harder or contains gravel, i.e. for colonised surface areas of less than 100 square metres. n F
Tarping is reserved for colonised surface areas of less than ten square metres. M P D C
n Examples of interventions on three sites A
© n Work site at Bendy, in the town of Logonna-Daoulas. The work consisted of digging trenches, removing plants using garden forks and laying tarps. 2. Lax-flowered sea lavender ( Limonium humile ). n Work site in Troaon. The work consisted of digging trenches and laying tarps. 3. Area colonised by smooth cordgrass. n Work site in Daoulas with the creation of a multi-test zone. The tests consisted 4. Cordgrass removal by scraping the surface, of tarping for two, three and four years and tests on germination. The purpose of done by the Finistère group of hunters in the maritime public domain, in a partnership with the experiments is to check whether a fragment of rhizome is sufficient or an Brest Métropole, the European university institute entire rhizome is required to produce a new plant in a favourable environment for marine science, the Armorique regional (bare mud flat). The results may confirm the importance of avoiding any dissemination nature park and Bretagne Vivante. of rhizomes. Seeds were voluntarily planted in situ to check whether the plants reproduce sexually (the hybrid is thought to be sterile according the the National botanical conservatory in Brest).
3 n Scientific monitoring 5 n Several monitoring sites for smooth cordgrass were established in 2011 by the LEMAR lab (European university institute for marine science). Phytosociological surveys are also carried out at specific spots or along transects. n The resulting chronological data are used to precisely analyse the expansion process and speed of smooth cordgrass within the vegetation in salt meadows. This monitoring provides valuable information that usefully complements mapping.
n e Unfortunately, due to a lack of funding, the monitoring had to be suspended r è i l l i
except on the “Ria du Faou” site. z r a L
. A n Waste management © n The smooth cordgrass removed by scraping the surface of small plots less than five square metres in size was transported to a farm or to an area in the immediate 6 proximity of the work site, taking care to ensure that it was placed well above the high-water mark (embankments) to avoid any risk of later dissemination. n The clumps of soil produced by digging the containment trenches outside of colonised areas were left on site because they did not contain any smooth cordgrass.
R
esults and costs e r è i l l n i The experiments conducted since 2011 by the Armorique regional nature park z r a L
and its partners were an occasion to test various techniques. A certain number . A were dropped (inefficient, physically difficult or overly expensive) given the poor © results obtained: - uprooting, mowing; 7 - removal stalk by stalk, except when mixed with stands of lax-flowered sea lavender (Limonium humile ), for example; - scraping the surface of soft mud; - trampling. n Other techniques proved more effective and may be used on other sites: - scraping and removal stalk by stalk on substrates containing gravel; e r
- mechanical means (if access by land is easy, however it would be useful to test è i l l i z access by sea); r a L
- tarping for a long period (five years); . A
- isolating small stands of smooth cordgrass by digging shallow trenches around © them; - repeated mowing prior to flowering. 8 n Résultats n No regrowth was observed in the scraped zones, on the condition that the rhizomes were completely removed. n According to an experiment conducted by the National botanical conservatory e between 2005 and 2010, tarps must remain in place for five years before the r è i l l rhizomes are completely destroyed. Tests are now under way on shorter durations. i z r a
n In situ L
tests of rhizome germination are also being conducted. . A
©
5. 6. 7. 8. Digging a ditch.
4 n Results on three sites 9
Bendy Troan Daoulas
Technique Trenches, removing Trenches and laying tarps Multi-test zone for e r
plants using garden forks tarping and germination è i l l i z
and laying tarps tests (in progress) r a L
Work days 2 days in 2012 2 days in 2014 1 day in 2015 . A
2 days in 2013 © 1 day in 2014
1 day in 2015 10 Treated surface area 1.5 hectare 112 sq. metres 16 sq. metres Number of people 2011: 4 people 10 people 10 people 2013: 10 people 2014: 8 people e r è i
2015: 10 people l l i z Results No regrowth in sectors The tarped plants Tarp well set in spite of an r a L
treated with garden forks were rapidly destroyed. outlet with a high outflow. . A
on substrates containing In the spot where the tarp No germination has been © gravel. was accidentally removed, observed for the time 9. 10. Laying tarps. Regrowth and progression the plants regrew. being. in sectors of soft mud. The clips on the tarp held The smooth cordgrass well, but the ends did not cross trenches of the tarp exposed to (except where trenches strong currents were torn. became filled in, hence The smooth cordgrass the need to rework the did not cross trenches. trenches every two years).
n Human and financial aspects n Scraping a colonised surface less than five square metres in size can be done by one person in a half-day. n Digging a metre of ditch takes one person five to ten minutes. n To date, the work on sites has been done by volunteers. n In 2015, an intervention was organised by a non-profit that specialises in “eco-volunteer” projects. * The cost was 1 000 euros for the two-day project. n The cost of the tools purchased in 2011 (shovels, pick-axes, forks, tarps, hand shovels, duckboards, pails, funded by Brest Métropole) was approximately 1 000 euros (the excavator is not included in this total). n The participation of a park employee was not calculated, but may be estimated at 5 000 euros since 2011. n The tarps cost 0.25 to 0.50 euros per square metre. n The excavator was lent free of cost by the hunting group.
5 n Intervention costs in euros (2011-2015)
2011 2012 2013 2014 2015 TOTAL
Number of work projects 2 3 1 2 2 10 Cost of work 0 (volunteers) 0 (volunteers) 0 (volunteers) 0 (volunteers) 1 000 (eco- 1 000 volunteer project) Cost of tools/equipment (tarp) 1 000 (in 2011) 0 0 0 30 (tarp) 1 030 Management costs 1 400 1 400 600 1 200 800 5 400 People involved (total per year) 40 30 12 18 18 118 Work days 5 5 1 4 2 17
Information on the project n Since 2010, each work project has been the topic of at least one press article. Public opinion is, on the whole, highly positive concerning the work. The articles have raised awareness concerning the problem. For more information n A public meeting on smooth cordgrass was held in the town of Faou in 2015. The results were positive with 20 people attending and new volunteers signing up for work projects in their town. New projects are planned in the framework of the n Internet site of the Armorique regional nature “Citizen days” organised by the town. park: n A report on the work was broadcast by France 3 Iroise television in 2011. http://www.pnrarmorique.fr/Agir/Preserver-labio - diversite/Lutte-contre-les-especesinvasives/La- Outlook spartine-americaine Spartina-alterniflora n Querne J. 2011, Invasion de Spartina alterniflora n A “2016 action plan” is being set up in a partnership with the Agency for dans les marais de la rade de Brest. Comportement protected marine zones. Extensive work is planned in several towns, namely invasif et impact sur le cycle biogéochimique du Loperhet, Hanvec, Le Faou, Argol and Pont-de-Buis les Quimerc’h. Firms silicium. 217 pp. n specialised in this type of work and volunteers will take part. Toupet J. 2010, Quelles solutions de gestion n The search for funding will be pursued to continue the work on the sites and pour l’espèce invasive, Spartina alterniflora , avoid regrowth, and to open new sites in the priority zones. en rade de Brest ? État des connaissances, synthèse bibliographique et perspectives de n A study is planned on the impact of smooth cordgrass on benthic fauna, travail, rapport de stage de Master 1, Institut migratory fish and birds hibernating in the area, in a partnership with local universitaire européen de la mer. 84 pp. research organisations (European university institute for marine science). n Le Noac’h J. 2011, Mise en place d’une ges - n A second partnership is now under way with the institute to test the resistance tion expérimentale d’une plante invasive en rade of smooth cordgrass to flooding under laboratory conditions. Further tests will be de Brest, Spartina alterniflora , rapport de stage conducted in situ . de master 1, Parc naturel régional d’Armorique et Institut universitaire européen de la mer. 63 pp. Author: Agathe Larzillière, Armorique regional nature park n Hourdé M. 2014, Mise en place d’un plan opérationnel de lutte contre l’invasion de l’espèce invasive Spartina alterniflora dans les sites Natura 2000 « Rade de Brest », Parc naturel régional d’Armorique. 47 pp. n Larzillière A. 2014. Document d’objectifs Natura 2000 – Rade de Brest-Estuaire de l’Aulne et Rade de Brest-Baie de Daoulas-Anse du Poulmic, tome 3 : Actions et opérations. Parc naturel régional d’Armorique, Brest métropole océane, Dreal Bretagne, 385 pp.
This management report was drafted in January 2016 by the work group for biological invasions in aquatic environments, set up by Onema and IUCN France, in addition to those already presented in the second volume of the book titled “Invasive alien species in aquatic environments, Practical knowledge and management insights”, in the Knowledge for action series published by Onema. GROUPE DE TRAVAIL NATIONAL http://www.onema.fr/sites/default/files/EN/EV/cat7a-thematic-issues.html Invasions biologiques en milieux aquatiques 6