Tasmanian trees and the benefits of mulching

Improving tree health

Mulching is a practice that involves covering the ground around trees with a protective material, such as woodchips, compost, cardboard, or plastic sheeting.

In this article we will be answering:

  • What are the benefits to mulching?
  • What sort of material should I use?
  • What are the potential disadvantages of mulching?
  • How to mulch?
  • How can we help?

Tasmanian Tree Care suppling mulch

Tasmanian Tree Care can supply and apply mulch to your trees

What are the benefits to mulching?

Mulching has numerous benefits to your trees, some of which are:

Reduction in water evaporation:

There are many abiotic factors that affect the loss of water in soil (evapotranspiration), such as sunlight, wind, and temperature. Mulch can reduce the temperature fluctuations of the soil, which in turn helps to reduce water loss through evaporation. Mulch also helps improve soil structure and fertility by slowly breaking down and providing organic matter to the soil which can lead to better root development and improved water-holding capacity in the soil.

Soil temperature control:

Extreme temperatures can damage the roots of trees, especially juvenile or newly planted ones. The extreme temperatures can stress the trees as the uptake of water and nutrients they need is restricted. Applying mulch can keep the soil cool during very hot conditions, or normal to warm conditions in freezing weather.

Reduction in weed growth:

Mulching can reduce weed growth by limiting the amount of light and space that some weeds need to germinate and grow. Covering the soil surface with a layer of mulch can prevent existing weeds from receiving the necessary light and water to survive and can supress new weeds from sprouting.

Improvement of microbial activity:

Some mulches can increase microbial activity in the soil by providing organic matter for microorganisms to feed on, promoting a healthy and diverse soil microbiome. Mulch can also improve soil structure and fertility by preventing soil compaction and reducing erosion, which creates a more hospitable environment for microbes to thrive.

Removal of residual effects of pesticides, fertilizers, and heavy metals:

Mulch can help reduce the residual effects of pesticides and heavy metals in the soil by reducing the rate of runoff and leaching into groundwater. Mulch can slow the movement of water through the soil which can reduce the potential for pesticides and heavy metals to be carried deeper into the soil. The increase in microbial activity from organic mulches can also help to break down and degrade some pesticides and heavy metals.

Decreased economical costs for watering, weeding, and maintenance:

Mulch helps retain soil moisture and reduces water evaporation, which leads to less frequent watering and potentially lower water bills. It also suppresses weed growth which reduces the need for hand weeding and the use of herbicides. An organic mulch at the right depth can also reduce the need for frequent tilling and soil amendment.

Tasmanian Tree Care suppling mulch

Tasmanian Tree Care suppling a fresh drop of mulch

What sort of material should I use?

There are many different materials that can be used for mulch. It can be broken down into two main categories: organic or synthetic.

Organic mulch is made from natural materials such as leaves, bark, wood chips, compost, or straw. These materials will biodegrade and improve the soil by adding organic matter and nutrients as they decompose.

Synthetic mulches, typically a black or clear plastic sheeting, can be laid over the soil. Plastic mulch has several benefits, such as conserving soil moisture and preventing weed growth, however, it is not biodegradable and does not add organic matter or nutrients back into the soil. Using plastic mulch can also have negative environmental impacts, as it can contribute to plastic pollution and may not be easily recyclable.

What are the potential disadvantages of mulching?

Although there are numerous benefits to mulching there are some things to consider:

  • Mulching directly against the trunk of a tree should be avoided as it can lead to rot, promote detrimental fungal growth, and cause improper root formation, such as girdling roots. 
  • Mulch that’s too thick can inhibit water from reaching the soil or can create an environment where moisture cannot escape. If moisture builds up in the mulch it can create perfect conditions for wood decaying fungi.
  • Some types of mulch, especially compost, can attract pests such as unwanted insects and rodents, which may damage the trees.

How to mulch?

There are many different materials that can be used for mulch that will benefit your tree. We are an advocate for using wood chips as mulch because it is organic material that decomposes, provides nutrients to the soil, and increases microbial activity. Another advantage of using wood chips is that the mulch from trees that have been removed can be recycled back into the soil, benefiting other trees.

  • Clear the area to be mulched of any existing vegetation or debris (this can be done by layering newspaper or carboard over grass or non-woody weeds).
  • Apply the mulch between 100-150mm deep over the intended area, making sure not to mulch directly against the trunk of the tree.
  • Water the mulched area thoroughly to help settle the mulch and activate microbial activity.
  • Maintain the mulch by adding a fresh layer as needed (usually once a year) and removing any sections that become compacted or contaminated.

How can we help?

Tasmanian Tree Care and it’s highly trained arborists can supply and apply mulch to your trees in your garden or property. If you’re unsure about the health of your natural assets, please contact us to organise an assessment.

Content collected 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.

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