What is ground protection?
Ground protection is a means to prevent compaction within Tree Protection Zones (TPZ). It usually consists of a physical barrier made from solid boards or equivalent that are installed over geotextile fabric and a thick layer of mulch (ideally 100mm or greater deep).
When in the development stage should ground protection be installed?
An arboricultural impact assessment should include a Tree Protection Plan (TPP) for the trees that are to be retained on a development site. The TPP will incorporate mitigation measures for impacts specific for the site. See our post on Tree Protection Plans here.
The TPP will include ground protection measures for any sections of the TPZ that are unfenced and accessible to machinery.
Some examples of ground protection include DIY rumble boards that are constructed of thick boards strapped together (fig 1), and Commercial grade mats such as Versadeck™ mats (fig. 2) or EuroMat™ (fig. 3).
Fig. 1: DIY rumble boards (Morton 2018).
Fig. 2: Commercial grade protection Versadeck™ mats (Envirex 2022).
Fig. 3: Commercial grade protection EuroMat™ (Ground Protection 2019).
Why is ground protection so important?
Compaction over the sensitive protection areas of a tree can inhibit the amount of water, oxygen, and nutrients that the fine, non-woody roots can absorb. This can adversely affect the health and vigour of a tree of any age, although trees verging on over-mature may be impacted more greatly.
The symptoms of this may include wilting or dying leaves, small branch dieback, and can even lead to the death of the tree in some circumstances. The symptoms from compaction may not be evident straight away, and the decline of the tree is not always associated with it.
Installing adequate ground protection means that the tree has a far greater chance of tolerating some of the impacts from development.
How does it align with the Australian Standards?
AS 4970-2009 Protection of trees on development sites (Australian Standards 2009) requires additional protection measures for trees, such as ground protection, when fencing cannot be installed within a TPZ.
I think my site requires ground protection – what now?
If you’re early on in the site design process, we recommend that a preliminary arboricultural assessment be undertaken to reduce the amount of back and forth between the architects, developers, and council.
If you’re at the stage of development of assessing the impact the development will have on trees, then you will need an arboricultural impact assessment. Part of the arboricultural impact assessment will include a Tree Protection Plan that will include ground protection measure for the trees that cannot be fenced off or isolated from the works.
Contact us for a chat about what’s involved with your development and how we can help.
Blog written by Mark Fahy
Mark has a diploma in arboriculture (AQF level 5) and is a registered Quantitative Tree Risk (QTRA) assessor. He has been an arborist for over 10 years and is passionate about trees. He is committed to providing evidence-based solutions and thorough reports to clients. Mark is specifically enthusiastic about living with trees in the ever-changing urban environment.
References
Envirex 2022, Accessed 8 December 2022, http://www.envirex.com.au/versadeck-medium-duty-applications.
Ground Protection 2019, Accessed 8 December 2022, https://www.groundprotection.com.au/specs/.
Morton, A 2018, North Stratfield Railway Station Queen Street, North Stratfield, arboriculture impact assessment, Earthscape Horticultural Services prepared for Transport for NSW.