Mechanical

managing-bracken-on-gower-commons

Mechanical management of bracken

Bracken control on the Gower Commons

Bracken was first identified as a management problem in the 1985 minutes of a Gower Commoners Association meeting:

Mr Robinson believed that bracken had increased threefold since the war and is now a major problem. In the past there were more heavy horses on the common which kept down the bracken.

Bracken overwhelms other vegetation and requires mechanical management, the modern day equivalent of being trampled by heavy horses. Bracken control has a key part to play in encouraging the growth and variety of other heathland plant species. This improves biodiversity and helps conserve habitats and wildlife.

Better grazing opportunities for commoners’ livestock are to be found as the quantity of bracken decreases and the growth of edible vegetation increases. Recreational access is also improved.


Scrub management on Gower Commons

Scrub is an integral part of any heathland habitat. Ideally 10% of a heathland should consist of scrub. Scrub and scrub woodland are both important habitats in their own right, particularly when managed for maximum wildlife benefit.

When managed well, scrub is a great resource for wildlife such as the stonechat and Dartford warbler. Scrub also provides shelter and shade for grazing animals.

Changes in vegetation gradually change the type of plants in an area over time. Without management, heathland would become dominated by scrub, eventually succeeding to scrub woodland.

Other plants managed on Gower Commons to ensure the balance of scrub to open heathland is correct include gorse, silver birch, willow, hawthorn and blackthorn.

Invasive species on Gower

On some of the Gower Commons rhododendron was planted by the large manorial estates as game cover for shoots. When these commons were sold the management of such vegetation ceased and the rhododendron spread. An example is from Ryers Down. In 1963 there is no evidence of rhododendron on the Down, but by 2001 seven hectares showed evidence of it.

Other exotic invasive plants on Gower Commons include cotoneaster, Japanese knotweed, Himalayan balsam and golden rod.

Gorse management on Gower Commons

Gorse is a native plant and despite being invasive, does have a role to play on our heathlands.

The are two types of gorse found on Gower are European gorse (Ulex europaeus) and Western gorse (Ulex gallii). European gorse is normally taller, growing up to 2.5 metres whilst Western gorse is normally under 1m. European gorse flowers throughout the year and has a distinctive coconut smell, whereas Western gorse only flowers from mid August through to October.

Gorse is of importance as a habitat for invertebrates, with fifty species of insects, including spiders, making their homes on the plant. Gorse also provides protection for reptiles such as adders who use it to shelter from the wind after coming out of hibernation in spring.

Traditionally gorse was used for fuel or milled to create fodder for livestock. It is also a food source for ground nesting birds such as the skylark.


Japanese knotweed

One species of invasive plant which cannot and should not be mechanically managed is Japanese knotweed (Fallopia japonica)

 

Japanese knotweed uses

In its native habitats in Japan, Taiwan and Northern China Japanese knotweed (Fallopia japonica) is a coloniser of volcanic lava flows. It has properties similar to bracken and binds and stabilises soils because of the complex rhizome (root) system. The canopy mimics a tree canopy, which can provide a habitat for bluebells.

Japanese knotweed is an attractive looking plant. Since its discovery in the early 19th century, it has been exported all over the world as an ornamental plant.

Japanese knotweed is sometimes cooked as a stir-fried vegetable, particularly in far eastern cultures. It has medicinal properties. The flowers provide nectar for insects. It can also be used as a vegetable dye and as a fodder crop.

Legal status of Japanese knotweed growth

Japanese knotweed is now recognised as the most invasive plant in Britain.

Japanese knotweed is included in Part II of Schedule 9 of the Wildlife and Countryside Act (1981). Section 14 of the Act states that, “if any person or otherwise causes to grow in the wild any plant which is included in Part II of Schedule 9, he shall be guilty of an offence”.

Invasive growth of Japanese knotweed

Japanese knotweed spreads by underground stems in a similar way to bracken. It can reproduce vegetatively and stems of under 1 gram in weight have the ability to generate new plants.

This invasive species grows at a rate of 5-10cm a day, reaching over 3m in height, with a radial spread from its root system of 7m.

As Japanese knotweed’s seeds are sterile, the major cause of its spread is human activity. The Gower Commons are affected in particular by the dumping of garden waste or contaminated soil.

Damage caused by Japanese knotweed

Japanese knotweed is recognised as a threat to biodiversity in the UK. It dominates and often out competes existing plant communities. Like bracken, it produces dense leaf litter which suppresses the growth of those species beneath by acting like a mulch.

It causes structural damage to buildings, pavements, walls and car parks as the rhizome extends to establish new shoots.

Japanese knotweed management

Control of Japanese knotweed is extremely difficult as it can regrow from small fragments of stem. However, extensive works have been undertaken to manage this invasive species in the UK.

Mechanical control of Japanese knotweed

The ability of Japanese knotweed to regenerate from tiny fragments of stem especially affects mechanical control of the species. Cutting, pulling and mowing is not always effective because if the plant debris is not properly disposed of then it will regrow very quickly.

Herbicide treatment of Japanese knotweed

Herbicide treatment of Japanese knotweed is not effective without an integrated and repeated approach. All precautions to limit regrowth must be taken.

Biological control of Japanese knotweed

There are methods of biological control of Japanese knotweed, unlike bracken. As it is edible, especially when the plant is young, it is susceptible to grazing from sheep, cattle, horses, donkeys and goats.

Japanese knotweed disposal

Disposal requires drying the plant out before either burning or burying off site. Japanese knotweed must be buried at depth to preclude any future regeneration.