Posted by Cain Blythe - CEnv MIEMA MCIEEM MSc BSc (Hons) on 12/05/2015
Over the last 25 years Ecosulis has developed a tried and tested method for establishing reedbeds in a variety of situations. Our experts know that each site has its unique set of challenges and these need to be considered systematically in order to ensure that you can establish a successful reedbed. Where we have been commissioned by clients to repair or restore failed reedbeds, we have identified factors that are often not considered by those installing them. This article outlines some of those key issues and provides solutions to them.
One of the key factors to consider relates to the size and age of plants. Plants grown and planted in the same year are rarely suitable for planting before mid to the end of June, although with certain minor species such as Myosotis and Mentha it is achievable. For the bulk of the major species such as Phragmites, Juncus, Lythrum and Iris it is difficult to obtain stock of any maturity within the same year and if such stock is supplied, projects can be compromised from the outset.
Wildfowl find the fresh growth of soft nursery stock to their liking and therefore such planting can be destroyed if there are unprotected plants. The recommendation on this basis is that stock planted in late spring should be from the previous season. Planting in April is possible but has higher risks since species such as Iris, Juncus and Caltha can be growing reasonably fast and their fibrous root system is active; however, plants such as Phragmites tend not to produce a fibrous root system until about May, so even though the tops may be growing, the plant rhizomes are more vulnerable to a variety of factors.
The following provide a list of the key factors you should consider with respect to your reedbed planting project:
- Nutrient status of substrate e.g. highly enriched substrates will result in rapid green growth but weak rhizomes, while imported reeds struggle in calcium enriched waters.
- Turbidity – high levels of turbidity can seriously affect plant development if the young plants are submerged for long periods of time.
- Water levels – high fluctuations in water levels or periods of prolonged submergence can kill off early stage reedbeds.
- Potential for algae blooms – nutrient enriched waters often form algae blankets which can smother leaves and result in poor photosynthesis.
- Weed establishment and competition – out-competition with nettles, docks or invasive species such as Japanese knotweed or Himalayan balsam.
- Bird predation – a small group of geese and high levels of coot and similar wildfowl can graze and permanently damage large areas of reedbed.
- Wind shear – sites that are exposed to high winds can damage young plants prior to establishment.
- Plant suitability and health – imported stock or plants poorly cared for can struggle to establish in new sites, particularly if they are not of local provenance.
Any one of these factors can have catastrophic impacts upon the success of reedbed establishment and therefore any reedbed establishment should be based on very specific local considerations and expert knowledge.
If planting is delayed for plants until May and Phragmites to the end of May or early June many of the above issues can be avoided, since nursery vegetation is growing fast and strong resulting in predation having little overall negative effect and fewer defects.