The importance of Weeding
By Dan Lazarou-West
The importance of weeding around newly planted trees cannot be understated. Weeds compete for light, nutrients and, most importantly, available water in the soil. In addition, weeds provide cover for bark-gnawing rodents and taller or climbing weeds. Bramble, for example, can smother and topple small transplants. Without an adequate weeding regime trees can suffer poor growth rates and in some cases die. Replacing recently planted bare root trees can be costly and is potentially avoidable. As you can imagine, replacing a more established tree can become very costly and, of course, you have missed out on any potential growth for every year the tree has been in the ground.
There are some weeds deemed so invasive that landowners have a legal duty to control them. Weeds like Himalayan balsam (Impatiens glandulifera) and Japanese knotweed (Fallopia japonica).
There are occasions where native weeds can add to the mix of diversity within woodland and no one can dispute the role flowering plants play as sources of nectar and food for larvae/ caterpillars and grubs. Open glades and woodland edge habitat benefit from many of these species with lots of woodland specialist butterflies associated with honeysuckle, nettles, bramble and thorns.
Spiny or thorny weeds can also provide a safe space for young oaks to grow free from grazing pressure. However, this is in the minority of cases and for successful tree establishment a growing condition free from weed competition for 3-5 years is best.
Some of the competition, of course, can easily get the upper hand. Weeds like ‘Fat Hen’ (Chenopodium album), which is the fastest growing of all the annual weeds, is able to produce from just a single plant 20,000 seeds in its lifetime. Equally, the seeds of plants such as rosebay willowherb (Chamerion angustifolium) and willows (Salix spp.) use downy hairs as aflight mechanism. Even more sophisticated are the tiny parachutes used by members of the daisy family, such as thistles (Cirsium spp.) This can ensure the seeds travel much further, drifting on the breeze. A dandelion seed can travel more than 5 miles through the air.
So you can see that weeds have developed to be successful and foresters must be on guard to ensure that target species are able to thrive.