Establishing trees in dense bracken

Bracken can be controlled by cultivation (and or ploughing). This method is rarely used on farms because of the difficulties of working on steep ground and the costs involved. However, there is specialised machinery that could be used for this purpose. Because trees are planted 2m to 3m apart it should be possible to prepare in strips rather than ploughing the whole slope. 

This project will trial techniques to cultivate strips of varying widths using different types of machinery suitable for working on steep ground. The treated strips will then be planted with trees and their subsequent growth monitored.

The project will run on two sites over two and a half years and will include ground preparation using a mini digger cutting shallow benches, a mini digger with cultivator attachment, a crawler tractor with cultivator, and a forestry scarifier and a robocut machine with a cultivator. Alternative techniques of post planting weeding will also be carried out for comparison such as a strimming, and manual bashing.

Four tree species saplings will be planted:

1. Sessile oak
2. Downy birch
3. Rowan
4. Sitka spruce

The majority of these saplings will be 45-60 cm in length which is the industry standard. One plot will be planted with larger saplings of 1 metre directly into untreated bracken to establish whether the extra costs of larger plants and stakes would be a more cost effective alternative than the experiments involving mechanical control.
The success of each technique will be monitored through survival and growth rate of the trees. A cost benefit of each technique will also be made and an estimate of the likely costs of each technique when employed on a larger scale. Once the trees become sturdier and grow higher than the bracken, the impact of the bracken will be sharply reduced. It is the first one or two years after planting where bracken competition is critical.

The results will be relevant to both to conventional and organic farms and provided the proposed techniques are effective they are likely to see widespread adoption particularly at a farm scale. For large-scale woodland plantings the comparative costs of mechanical techniques versus helicopter spraying is likely become a more critical factor. However, mechanical ground preparation confers other advantages than bracken control alone and it is by no means a foregone conclusion that mechanical control would not be a more cost-effective option.