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Picking the Right Plant for the Job
From erosion protection to providing shade for your animals, there are many good reasons for planting trees, but getting your selection right can be tricky.
Alice Trevelyan of Waikato based native nursery and Farmlands Card Partner The Native Dairy Farmer has helped hundreds of farmers with their planting decisions, including in her former role as a Senior Catchment Officer at the Waikato Regional Council. Her number one piece of advice when considering planting is to look at how it will fit within your whole farm system. “How do you see the area looking in 10 years? Is it going to be an area you would like to graze or is this an area that you're happy to retire and maybe look at other potential forms of income? “That's a good starting point, especially on hill country because there are a lot of options.”
Holding the Hillside
Erosion and slips are a problem for many farmers, but these risks can be mitigated by planting the right trees. Alice says there are options with both native and non-native plants. “Manuka and kanuka are great native options for large-scale steep erosion areas. They give you really fast coverage, growing quickly even in low fertility sites. You can then look to get other sources of income from that area, for example, carbon credits or you might be able to look into Manuka honey.” One of the most popular options for hillsides is poplars, which Alice says are a multi-purpose tree.
“Poplar poles are great for erosion protection. After the first couple of years, once their root systems have established, you can let sheep and cattle in underneath so you can still get the grazing benefits.” Poplars are deciduous, allowing for continued grass growth under their canopy, with vegetative cover providing further erosion protection. Alice points to another benefit of using poplars: their leaves can be used as a supplemental feed option. “The leaves have the same nutritional value as lucerne hay, so they're a really good feed source in the summer or during a drought.” She says it’s important to get your spacing right, and poplars also require regular maintenance.
“You can't just plant them and leave them for 30 years. Trimming branches back to a single leader and ensuring that the tree does not become too top heavy will increase the life expectancy of the tree and provide greater erosion protection benefits.” Another tree commonly used for erosion protection in wetter seeps or the riparian area is the Salix matsudana, commonly known as the Tortured Willow or Corkscrew Willow. “They're sterile like a poplar pole, growing straight, not sprawling like your Crack Willow or your Pussy Willow,” Alice explains. “You might have a slip that's got a really wet area at the bottom and the willows can handle their feet being wet, so they're a great option for those areas, and for stabilising a bank when you’re riparian planting.”
Gimme Shelter
Protecting animals from the elements with shade can improve their health and welfare and potentially even their production. Poplars are also commonly used as shade trees, but Alice says picking the right plant all comes back to the purpose. “Some people may want to see a little bit of colour out in the paddock, so they might go something that's got beautiful red leaves, like Pin Oaks, or a red maple. “With regards to native shade trees, lots of people use totaras and akeake; both are really good shade trees. It all comes back to your kind of soil type and the area that you're planting, but there are a lot of different options out there. “We've just planted a whole lot of banksias as shade trees on our own farm. They're super-fast growing, and they've also got a beautiful flower for the tuis.”
Another common use for trees on farm is firewood, and Alice says there are certain species that work well for this purpose. Hard wood species such as eucalyptus (or gum) are very popular as they are fast growing, burn well and also coppice (grow back when cut). Alice encourages farmers to think about the practical implications of what and where they are planting, including how it could be affected by future changes in land use. “Is the land going to be cropped? Having a large tree planted in the middle of your paddock, or too close to gateways might be a pain for large equipment. You also want to think about the placement of your water troughs relative to where stock will graze, camp and seek shade. “It’s important to provide adequate fencing for your planting projects. If you want it to last, you need to protect it.”
Site-Specific Needs
Riparian planting to protect streams and waterways can be even more complicated, and Alice says there are many factors to consider, including everything from fence placement to local regulations. “You might have a shallow flowing stream, or you might have somewhere that's eroding or subject to flash flooding. It’s all quite site-specific.” Flax is a popular choice for riparian planting, but Alice says you need to be careful planting it too close to the water's edge, especially if you've got a channel where the water level rises frequently. “Flax has a really shallow root structure compared to its mass, so it can become very top heavy, and if you're getting that constant change in water level it can actually cause erosion rather than protecting against it.”
For wetter areas, Alice says carex grasses such as carex geminata (also known as cutty grass), are a great option. “Carex geminata spreads through a rhizome in its root system to form a carpet, so it's a great erosion protection option and can tolerate being completely flattened and stand back up.” “Cabbage trees are another great species as they've got a real nice deep tap root. They can tolerate a change in water levels and they're a great stabiliser in the riparian margin. Manuka is also great as it can handle its feet being a little bit wet, whereas kanuka prefers the dry.” Whatever you are planning to plant, Alice says it’s important to get the right advice before you pick up the spade. “I would recommend talking to your regional council or people like ourselves with experience working in the industry. They'll be able to help you with species selection, and they might have options for funding, which is always a great opportunity to tap into.”
For more information about your planting options, go to www.thenativedairyfarmer.co.nz
