Bamboo, whilst causing problems due to its invasiveness, can also cause problems with health and safety in some scenarios.
Southwest Knotweed, were asked to conduct a full removal of two stands of Bamboo (Arrow Bamboo) at a school in Cornwall, due to the sharp culms which could cause potential injury to children utilising the recreational space.
The images below, images 1-3, depict the large stand of Bamboo requiring excavation and removal.
This bamboo forms dense clumps and sends out runners to create new clumps.
IMAGE 1 – Bamboo Stand pre-excavation
IMAGE 2 – Bamboo Stand pre-excavation
IMAGE 3 – Bamboo Stand pre-excavation
Despite not being a particularly mature stand, it was planted in virgin soil without protective membranes, this allowed for rapid escape of the plant from the initial planting area.
In just a few short growing seasons the plant had well and truly taken over the area, also exploiting voids under a greenhouse. This demonstrates nicely why appropriate containment measures should always be implemented when planting invasive species, in addition to an assessment of the appropriate risks – be that physical or toxicological.
Images 4 & 5: Illustrate how quickly invasive bamboos can dominate an area when not appropriately contained. Image 4 taken in 2017 vs. Image 5 taken in 2022.
The areas of Bamboo totalled a rough square meterage of 80-100m2. These were located growing in and around a fence, running through areas of turf and both under and through a raised planter.
The initial Survey carried out by Southwest Knotweed, did not fully estimate the extent of plant runners under the grass playing area within the school, due to the weekly ground maintenance (grass cutting), masking the extent of the area occupied by this invasive bamboo.
PHASE 1: Initial Scrape of Bamboo areas and removal of dense mature clumps.
Image 6: The initial excavation involved the disruption and removal of the dense areas of Bamboo. Southwest Knotweed, using an excavator, carefully removed as much of the plant rhizome from the top 200-300mm of soil (>90% of Bamboo plant rhizome is in the top 300mm of soil). Due to the makeup of the ground the excavation areas remained shallow.
Image 7: The excavated material was taken by dumber truck to a membrane and deposited for collection by the waste carrier.
PHASE 2: Chasing of runners and clearance of excavation sites.
Image 8: The bamboo “runners” were then chased through the soil and excavated to their terminus.
Image 9: The excavated area is tidied of plant debris and checked for remaining fragments and runners. Careful consideration in inspecting all areas, especially the edges where excavation took place. Specifically looking for rhizome runners.
PHASE 3: Making good of excavated area and revegetation.
Making good of an excavation site is particularly important. This is true for several reasons, (1) when excavation pits are deep, these can represent a health and safety risk to site workers and in some cases the public. Therefore, either filling post excavation with clean soil or appropriate fencing and signage is of paramount importance. (2) Revegetation is also particularly important, not only does this bind new surfaces together, but also minimises against the re-infestation of other invasive species, either native or otherwise.
The replacement of one invasive species by another can often be observed, following remediation works that remove vegetation from an area, either herbicidally or mechanically. This phenomenon is most obvious adjacent to water courses, which provide an excellent pathway of spread for plant fragments or seeds downstream.
Image 10: Following the completed excavation inspection, the area is backfilled with clean soil and revegetated with new turf seeds ready for the start of the new school term.
Image 11: The completed Bamboo excavation area following back-fill, levelling, and re-seeding.
Image 12: Collection of plant matter/soil by grab lorry taken to landfill.
Under current guidelines, no Bamboo in the UK is listed on the Wildlife and Countryside Act 1981 Schedule 9 list. Therefore, no waste regulations apply when it comes to disposal.
KEY POINT: Running Plants and Structures
Image 13: This neatly demonstrates the running nature of Bamboo roots. During the excavation, as above, the removal of the solid base for the outbuilding showed how the plant exploited, firstly, the void between two paving slabs which made up the solid base for the mounting of a greenhouse/outbuilding. Then, upon encountering resistance from the wooded edge, changed direction and exploited the void between where the slabs were buttressed against the wooden edging. This shows two things of note (1) weaknesses or voids are readily exploited by running plants generally and, particularly, by the likes of Bamboo and (2) When these plants come up against resistance, normally they simply change direction and take a path of less resistance where available. This demonstrates that, whilst these plants will exploit voids and weaknesses with ease.