Natural recolonization is considered to be the most ecologically sound approach to establishment of woodland, scrub and hedgerow vegetation. However, because Planting requires a much shorter timeframe, it is often the method of choice. Native Irish plant material can be purchased from nurseries, however, a lot of planting stock is not of Irish provenance and it is recomended that Native Irish plant material of Irish provenance is used. Hardwood cuttings can be used to propagate some species, for example Willow. Seed can be collected from other species, taking care to store, process and sow it correctly.
Planting can be assisted through the process of natural recolonisation. For example, when establishing an Oak-ash-hazel woodland (WN2), oak and ash whips of local or Irish provenance can be planted on a site to establish the canopy and the understorey. The ground flora species can be allowed to colonise the site over time from an adjacent WN2 woodland, if present. If the site is immediately adjacent to WN2 woodland natural regeneration can be accelerated during ‘mast’ years by ‘scarifying’ (shallow ploughing with a harrow) the topsoil prior to seed fall to provide a good seed bed for the resultant seed. This applies to the development of any native woodland type.
In addition, soil can be brought in from a donor habitat which contains the seed bank of the habitat which you want to recreate. This often occurs where a proposed development may disturb a habitat, and as part of the landscape mitigation plan the soil from the habitat must be stripped prior to commencement of construction and utilised elsewhere to establish a compensatory habitat. The seed bank contained within the soil will provide a source of seed for species which are not available from nurseries as certified Irish provenance material. It can also speed up the establishment process by providing ground cover species that would otherwise take longer to arrive on site through wind or animal/bird dispersal.
Sods or ‘plugs’ from a donor site can also be utilised to complement planting. This approach requires the lifting of small sections of sod from a donor habitat, ensuring that the sod contains both the plant and root stock and transporting it to the intended site where it is planted into the ground. This process provides a source of seed and a source of live plant material, which can grow and spread across the site. When considering this approach it is important to remember that the sods will need attention during storage and transportation to ensure that they do not dry out and may also need watering when they are placed in the ground. Cuttings from species such as willow also provides an alternative to tree and shrub planting.