Plant trees for growing gains

Bad weather is a key cause of animal suffering and providing shelter where none naturally exists is one of the few things farmers can do to help stop it. Planting a shelterbelt of trees is clearly a good longer term option.

It’s common sense that reducing stress on stock, including dairy cattle, can help keep their productivity and farm balance sheets healthy. And recent research confirms that sheltering and feeding ewes before lambing has a major impact on reducing lamb losses. 

Shelterbelts also help to reduce evaporation of soil moisture and transpiration from plants due to wind. Live shelter is particularly helpful in retaining soil moisture in prolonged dry spells, thereby supporting pasture growth for longer periods.

And shelterbelts improve the microclimate of plants and soil by improving plant water relations, conserving heat and reducing wind damage to grass leaves, which can stunt grass growth. 

Erosion prevention is another benefit of shelterbelts as they help control the removal of top soil by the wind, especially when used alongside other sustainable land use practices such as minimum tillage.

Other benefits of shelter trees include their providing a haven for native birds, sheltering homes, buildings and stock yards, improving aesthetics, increasing the tree species in an area, and supporting a range of insect life. Using native plants, particularly those naturally occurring in the locality, helps to preserve local character. 

Shelter can also screen noise and reduce odours from livestock operations.

When establishing a shelterbelt, careful consideration needs to be given to site selection and the tree species to be used. Terrain, local weather conditions and livestock behaviour are factors to take into account. Strategic planting is likely to be more worthwhile than blanket planting.

Shelter is most effective when sited at the correct angles to the eroding wind. If east-west belts are required they should include deciduous species to lessen the winter shading of pastures.

The density of the trees in the shelterbelt helps determine the wind behaviour on the leeward side of the shelterbelt and also, to some extent, on the windward side.  Practical experience shows belts of medium density produce a much more even wind flow over a much wider area. The correct density can be achieved by careful species choice, recommended spacing between the trees and management. If belts are too dense, this can create turbulence either side of the prevailing wind. But also remember  if gaps in a shelterbelt are too big this can cause the wind to funnel through at speed.

Generally speaking, the longer the windbreak, the better the protection for stock and pasture. Finally, tall shelter gives the most economic protection as the area protected is directly related to the height of the windbreak.

As always, it can pay to get professional advice on shelterbelts to help ensure farms get the maximum benefits from any spend on tree planting. 

• Bala Tikkisetty is a sustainable agriculture coordinator at Waikato Regional Council in Hamilton. Telephone 0800 800 401 This email address is being protected from spambots. You need JavaScript enabled to view it.