Species introduced from foreign countries that escape freely in the wild, disturbing or hindering the growth of native species, are referred to as invasive alien species (IAS). For plants, the level of disturbance is usually categorised by the rate of their spread in a natural habitat, thus taking the space and nutrients from native species competitively. Therefore, the faster the spread, the more invasive and dangerous the alien species is.
The most successful and notorious plant invader in the Maltese islands is the gracious cape wood sorrel (ħaxixa Ingliża). It was introduced in the beginning of the 19th century as a dozen or so plants that were found at the Argotti Gardens. The sorrel escaped and became the most common wild plant in Malta only after about 100 years. It can be found growing in many habitats in all islands, including Comino and Filfla, even if it does not form seeds. Propagation is by underground bulblets.
Despite its charismatic and fragile appearance, the cape sorrel hideously dominates and covers vast areas of land, leaving almost no space for other local plants to germinate and grow. Its distribution is so vast and invasive that nothing can be done to control or eradicate it.
However, if an action had been taken in its early stages of spreading, the Maltese countryside would probably have a more diverse plant community, including wild plants that are now rare, such as the pheasant’s eye (għallet is-serduq) and crown anemone (kaħwiela).
Modernisation has brought about a drastic increase in travelling, importation of plants and ease of buying plants online, resulting in a rapid escalation of foreign plants entering and growing in our country, usually for ornamental or agriculture use. Inevitably, the risk of getting IAS entering the natural ecosystems has also increased.
Indeed, the number of plants declared as invasive species in the Maltese islands has risen from somewhere around 10 plants to some 40 species in the last 50 years. Of these plants, the species known as the African or crimson fountain grass (Pennisetum setaceum) is one of the IAS that are of EU concern. The European Commission obliges countries, including Malta, to control and eradicate such species via the commission implementing regulation 2017/1263.
The commission has recently added two other IAS present in Malta: the lead tree (Leucana leucocephala) and the blue-leaved acacia (Acacia saligna) in a subsequent update, the CIR 2019/1262. These topmost invasive plants are illegal to import, sell, introduce or have in a non-contained possession, that is, where their seeds can be dispersed in the wild.
Removing African fountain grass in Gozo
In 2018, the EcoGozo Directorate within the Ministry for Gozo initiated a project to control and, possibly, eradicate the African fountain grass from Gozo. This plant forms elegant tussocks about a metre in diameter made up of many narrow arched leaves and numerous crimson-beige feathery inflorescences. Each plant produces thousands of seeds that can be dispersed by wind, water or ants.
During surveys carried out by the directorate and reports submitted by the public through the free e-government mobile application called myGozo, the fountain grass has been recorded in over 60 sites in Gozo. The localities where it has been recorded the most are Għajnsielem, Xagħra and Qala.
Interestingly, it is barely found towards the eastern half of the island and it appears that the spread started at the eastern part and moved westwards. Plants have mostly been found in urban areas, especially along streets, paths, walls and abandoned construction sites, but have also been spotted in some public gardens or private terraces.
The public has satisfactorily cooperated when approached to remove them from their gardens. The local councils of Munxar and Xagħra also helped to remove the fountain grass from public parks they administer.
In line with ERA’s guidelines for the management of alien species, EcoGozo appeals to the public to replace this exotic grass from their gardens with non-invasive plants to reduce threats to the local flora. More worrying is the presence of the fountain grass in two natural sites: Wied tar-Ramla (Xagħra) and Wied tal-Kapuċċini (Victoria). These sites are monitored more frequently to ensure that dispersed plants are removed promptly without further propagation in the respective valley systems.
“It is too early to claim complete success for the seeds remain dormant in the soil for several years”
Besides the mapping, the directorate has carried out numerous site visits, where plants have been uprooted and disposed of at tal-KUS waste facility in Xewkija. The flowers are first removed carefully from the plants to avoid further seed dispersal. Approximately 1,000 plants have been removed from Gozo by hand. These sites are then monitored one to three times yearly.
On some occasions, plants reappeared after three years, suggesting that seeds can remain dormant in the soil for a long period of time and persistent monitoring is key to successfully controlling this invasive species. The results are very promising: an estimate of 90 per cent of the total population has been eradicated. Continuous ecological monitoring ensures that new offsets are removed before flowering and seeding.
Indeed, the fountain grass is not normally noted when one visits Gozo, whereas the situation in mainland Malta is sadly a different one. This makes Gozo one of the few, if not only, populated islands in the central Mediterranean region where this alien species of EU concern is successfully controlled. Determination, perseverance, monitoring, professional removal and prevention of reintroduction are the key factors to this success.
However, it is too early to claim complete success for the seeds remain dormant in the soil for several years. Some populations in private properties also need to be addressed. Monitoring and cooperation may, hopefully, lead to complete eradication in the coming few years. Gozitan residents who have fountain grass in their gardens can contact EcoGozo to have it removed free of charge.
Stephen Mifsud is a senior medical laboratory technologist and botanist at EcoGozo, who is managing the eradication of the African mountain grass. The MyGozo app is available for download on the Google Play store.