Humans may need to manually intervene in areas where large machinery cannot reach. However, some areas may also be difficult, or unsafe, to access on foot.
Size of the site: The size of the area that requires Spartina removal will influence the methods to be implemented. For example, very small areas could be managed manually by removing plants by hand. However, this is a slow process and would therefore be impractical at a larger scale (Hedge et al. , 2003). Time of treatment : The time of the year the control measure is taken can influence its effectiveness. Evidence from China suggests that the optimal time for mowing is early June to early July, i.e. from the end of the vegetative growth period to the flowering stage (Xie et al. , 2019). Use of heavy machinery : It can be challenging to use heavy machinery in wet, soft, intertidal sediments. Furthermore, vehicles can displace or compress any vegetation present and could have potential adverse impacts on benthic invertebrates in the sediment (Evans et al. , 1999; David Melville, pers. obs.).
4. Implementation
Spartina has a strong capacity to withstand physical stresses and can therefore rebound quickly following physical controls (Wang et al. , 2023). This highlights the importance of planning a consistent removal effort and follow-up monitoring to quantify risks of reinvasion.
Cutting or mowing: Cutting/mowing creates open areas more quickly than herbicides (David Melville, pers. obs.). Cutting/mowing can be done with hand-held equipment or with machines (boats) capable of accessing both land and water. However, Hedge et al. (2003) reported that mowing machines were too fragile to use in estuarine environments. The timing of mowing needs to be considered (see above). Repeated mowing may be necessary, although Sheng et al. (2014) found that repeated mowing reduced Spartina stem height but did not eradicate it. It is noted that cutting may reduce abundance by 100% at the time of cutting, but may not reduce abundance thereafter (David Melville, pers. obs.).
Different machines can be used to cut Spartina. Pictured here is a mini harvester/cutting machine. [Credit: David Melville].
Uprooting: Hand removal of Spartina by uprooting the plant requires few resources but is labour intensive. The entire underground rhizomes need to be removed to prevent regrowth, but these can be over 1 m deep in the sediment (Hedge et al. , 2003). Uprooting can also be done by ploughing. Ploughing loosens and mixes the sediment and can damage Spartina rhizomes. A study in China found that ploughing at the end of the growing season prevented Spartina from reproducing (Xie et al. , 2019). Despite its effectiveness according to the evidence (Reynolds et al. , 2023), some practitioners urge caution when using ploughing due
101
Made with FlippingBook - professional solution for displaying marketing and sales documents online