Ways to improve natural assets on a farm Establish shelterbelts

What are shelterbelts?

Shelterbelts are strips of woody vegetation usually established between paddocks to reduce windspeeds and provide shade and shelter (Cleugh 2003). Some older shelterbelts were strips of a single species of tree, sometimes non-native trees, often called tree lanes. These tree lanes provide minimal shelter due to the lack of bushy understory, and don’t provide the biodiversity benefits of native shelterbelts.

For maximum benefit for shelter, shade and biodiversity benefits, shelterbelts should be planted with a mix of native species, usually both trees and shrubs, and are ideally at least 30 m in width. However, a strip of native plants of any size is beneficial. Some landholders have chosen to establish shrub-only shelterbelts which can still reduce windspeeds and provide significant benefits for biodiversity, including for pollinating insects.

Shelterbelts are not a new idea – work by groups such as Landcare and Greening Australia have facilitated the planting of shelterbelts since the 1980s. However, years of monitoring these shelterbelts and observing what does and doesn’t work means there is now an extensive body of scientific literature to guide how best to design and plant shelterbelts.

Planning and planting shelterbelts

Establishing shelterbelts and other plantings is a long-term investment in a farm’s future. So it makes sense to take advantage of the insights gained from previous planting experience – and from the twenty years of research undertaken by Sustainable Farms ecologists.

When designing and planting a shelterbelt, here are some factors to consider.

Where in the landscape can your shelterbelt have the greatest positive impact?

• Is there an exposed paddock that requires more shelter for stock? Shelterbelts can significantly reduce wind speeds, with benefits for pasture production, lamb survival and stock weight gain.
• Could planting along a drainage line help minimise erosion? Easily eroded areas may be stabilised through the establishment of a fenced planting.
• Are there other planted areas or patches of remnant bush that a new shelterbelt could help “connect”? Connected areas have greater combined value for wildlife.
• Could your new shelterbelt be established around an existing paddock tree? Large old trees give new plantings a head start, and in turn planting around a large old tree will help prolong its lifespan.
• Don’t plant shelterbelts in native grassland, as these areas are extremely rare and valuable.

Plant wide, dense shelterbelts 

• Wide plantings and plantings with an understory provide greater wind control. This is good for stock, crop and pasture production, and can also reduce the speed at which grassfires travel.
• A useful target width is 30m. If this is not possible, narrower plantings can still be valuable especially if linked to other areas of vegetation.

Plant native trees, shrubs and ground cover

In Australian conditions, there are many reasons to plant native shelterbelts:

• They are adapted to local conditions and more likely to survive and thrive – as well as to bounce back after a fire.
• Native vegetation provides essential habitat for native wildlife. Many of our native species are threatened by extinction, and a shelterbelt of native vegetation can provide badly-needed food and habitat for these animals.
• Native vegetation is less likely to support exotic bird species, some of which are agricultural pests. Instead, it will support native bird species – as well as native invertebrates, including pollinators.

Fence shelterbelts

• Maintain fences around shelterbelts. Research shows that heavily grazed shelterbelts are less valuable for birds and reptiles.
• Gates are important to allow access for feral animal and weed control. Extra gaps between mature trees are also important to facilitate access between paddocks during emergencies such as fire.

Managing existing shelterbelts

Once you have a shelterbelt, it’s important to continue managing it so that it can continue to deliver benefits for the farm and wildlife. Old shelterbelts can also be improved – and the benefits will flow much quicker than if you’re starting from scratch.

Management actions for existing shelterbelts

Maintain fences to control grazing pressure. Lower levels of grazing lead to increased vegetation cover, more leaf litter, less bare ground, and more species of birds and reptiles.

Add new plants to replace those that die in the early years of establishment. New plants might be needed to maintain the structural diversity of the shelterbelt – that is, so there’s a mix of trees, shrubs and groundcovers.

Add fallen timber. If a log or fallen branch is in the way elsewhere on the farm, don’t burn it – move it into a shelterbelt where it can provide great habitat for animals like yellow-footed antechinus.

Control pests and weeds. Shelterbelts can be a useful focal point to concentrate pest control efforts.

Repair and rejuvenate older shelterbelts. Sometimes, old shelterbelts become less effective. Perhaps fences have fallen down, enabling stock access and meaning understory and groundcover plants may struggle to persist. Perhaps the original shelterbelt was narrow, or planted with trees only, and isn’t a very effective windbreak. But old shelterbelts have great potential for wildlife and, with some rejuvenation, will quickly offer benefits for the farm as well.

Will shelterbelts and extra plantings turn a farm into a fire trap?

Some farmers are concerned that more trees on a farm could increase the fire risk. However, research by leading fire scientists (Collins et al. 2014; Jenkins et al. 2019) shows that adding plantings to a farm landscape very rarely elevates fire intensity above suppressible levels.

In slowing and interrupting wind, shelterbelts may help slow fire, particularly fast-moving grassfires. Windspeeds can be important drivers of fire behaviour and the ability of shelterbelts to check these speeds can be critical.

It is however important to consider planting design and location in the landscape in the context of fire.

• As well as gates, it’s important to leave occasional gaps between large trees to allow emergency access between paddocks.
• Don’t plant too close to homesteads and other built infrastructure. Studies of house loss show that property damage is reduced where vegetation is more than 30 metres from a house (Gibbons et al. 2012).

Unlike built assets like fences and infrastructure, natural assets have the capacity to regrow. Many Australian native plants will regenerate after a fire, and the seeds of species such as Acacias will readily germinate after fire. Healthy natural assets of all types are also more likely to bounce back than those in poor condition. For example, dams or riparian areas with good fringing vegetation are less vulnerable to pollution by ash and soil run-off following fire.

Designing shelterbelts for wildlife