Coastal sand country under the microscope
Joined the NZ Farm Forestry Association’s national conference for two days of field trips around Manawatu.
Words like mycorrhiza and phrases like production thinning and stems per hectare rolled off the tongues of three busloads of farm foresters on a tour of Manawatu.
Most of them had attended the New Zealand Farm Forestry Association’s national conference in Feilding, which was followed by several days of field trips around the region.
Coastal sand country, a distinctive feature of the Manawatu-Whanganui region, was under the microscope, including fore dune management at the Santoft coastal protection/ production forest. Sixty years ago, where the forest is now was raw, drifting sand. This is mostly state forest with Ernslaw One having cutting rights, although some areas have been returned to local iwi.
The forest was established in the early 1950s to protect farm land from the encroaching sand.
Planting of the dunes started in 1955 with a regime of marram, tree lupin and radiata pine. Later native spinifex was added between the rows of marram. The forest has 30km of coastline and about $2 million has been spent since 1990 keeping the fore dunes in place.
Dune fields cover about 100,000ha of coastal land from Paekakariki in the south to Patea in the north and reach their widest extent, about 20km, just south of Palmerston North.
Botanist Vivienne McGlynn spoke about the effort to manage conservation issues with the moving sands. Reading a 1911 report from the House of Representatives brought a laugh and then nods of approval from the farm foresters on the field trip. One quote described the evil sand as a whole pile of mischief but guessed the final treatment of the dunes should ‘‘assuredly be afforestation’’.
She talked about how the sand came to be in the area, coming down from the volcanic plateau and the Ruahine Range, and how plants had adapted to the extreme conditions - desiccation, dehydration, burial by sand, burial by water – and evolved over centuries for their seeds to survive until habitat opened up.
‘‘The problem these days is that there is less and less of that habitat so the challenge to you as stewards of your land, in what is really a short blip in geological and biological history, is to ensure you still have places for these rare, threatened or just native species to continue into the future.’’
At that point an interesting impromptu debate ensued about whether all the work being done to protect and enhance biodiversity was making a difference – in the interests of the organisers’ timetable the debate was left for another day.
Two sand country farm forestry properties were visited.
The Dalrymple family farms about 4000ha including Waitatapia, a 1450ha cropping and finishing property stretching from the Santoft forest to the Rangitikei River, which is notable for extensive irrigation (31 centrepivot irrigators) and high tech land management including precision contouring. They also farm the former Flock House block with other owners.
In recent decades, a large portion of the sand country has been contoured and levelled, with the knowledge and involvement of the Horizons Regional Council, to allow more intensive use of the land for finishing sheep and cattle and cropping. Arable crops include barley and wheat and maize for silage. Horticulture crops include pumpkin and squash, onions, potatoes, squash, celery and lettuces (irrigated).
‘‘That’s a really good example of the development over time of the sand country… now you can see a lettuce crop that is probably 50 per cent of the North Island lettuces over this winter,’’ says Hew Dalrymple. He and his brother Roger manage the business, which has a business development manager, five operations managers – dry stock, dairy, cropping, development and logging – and 31 staff.
The business has more than 400ha of plantations in a logging cycle. One 40ha block of 28-year-old trees netted $564 tonne a hectare last year.
Dalrymple’s take-home message was ‘‘if you start selecting something, start from a broad base, whether they’re trees or animals or people. If you want to have a one-hit wonder you’d better get it right. This industry has too many pets but it’s not prepared to let them go. The key to scale and success is to start with enough to breed from. It’s a numbers game.’’
Alternative species enthusiasts were at home on Denis Hocking’s nearby Rangitoto farm. This 247ha property with about 110ha in dune plantations, is on the bigger, higher, more inland ‘‘Foxton phase’’ dunes. It has a wide diversity of alternative species including mature stands of cypresses and various eucalypts.
The major dune, Rangitoto, possibly the highest dune along the coast, had been planted for soil conservation reasons in the 1890s and was on its third rotation.
When Hocking took over the family farm in 1975, there were 30ha of ‘‘generally well-managed’’ plantations plus 130ha of pasture running a bit under 2000 stock units.
‘‘I continued an annual planting programme with radiata pine but wanted to diversify and eucalypts looked an attractive option. Official advice proved to be little use and it was only when I linked with Murray Faulkner at Centrepoint Nurseries that I was able to try a wide range of species and find some sand country winners.’’
E. muelleriana had been the stand-out performer but other stringybarks had also performed well.
Hocking said forestry and livestock continued to co-exist well on the property, although forestry had generally out performed the livestock in the past 27 years.
The following day Horizons Regional Council staff hosted a field visit to Goulter’s Gully in the Pohangina Valley.
The impressive historic erosion feature suffered from severe erosion after settlers had removed the stabilising forest cover. Thanks to the former Catchment Board, planting started in 1967 with about 115,000 willow and poplar stakes planted by 1976. From 1972 to 1978 more than 70,000 radiata pine seedlings were planted. These were harvested from 2002 to 2004 and replanted – just before the 2004 floods, which the system weathered reasonably well.
The three busloads of farm foresters (plus a few extras in their own vehicles) followed the watershed of the Pohangina and Orua Rivers, on the east and west respectively, along Ridge Rd to view afforestation under the regional council’s sustainable land use initiative. There was talk about one block that was replanted after severe wind damage and the following dealings with insurance. The geology of the area also came under attention.
Former Tararua District Council mayor Roly Ellis told the farm foresters about the council’s own foray into forestry. It had previously had 55 per cent of its forest holdings felled for ‘‘not a great return’’ because the planting, spraying, pruning and thinning had not been done well.
The council changed to a logging company that knew the property and the forestry company had to report back to the council twice a year.
‘‘We want to make sure the forest will be producing good returns in 25 years’ time. With the right advice and contractors and top communication the council now has a good asset that is being well managed.’’