Farm Forestry New Zealand

A three phase harvest on the sand

Richard Weldon, New Zealand Tree Grower May 2018.

I recently completed harvesting my forest at Waikawa Beach near Otaki north of Wellington, with some pleasing results. The terrain is rolling to steep sand dunes, interspersed with swampy gullies.

The total forest area was 21 hectares, planted in two stages −11 hectares in 1992 and 10 hectares in 1993. The forest was high pruned in two lifts and waste thinned to a stocking of around 400 stems a hectare. Tree form was generally very good with straight trunks and relatively small branches.

During 2012 when the oldest trees were 20 years old, it was suggested to me that the stand should be production thinned. The stocking was judged to be a little tight and the trees were possibly not going to reach their potential. The trees at that time were standing at an estimated 400 stems a hectare, with an average tree size of just under one tonne. I was approached by Sharo Sievers of Horowhenua Harvesting, a locally based logging contractor contracted to FOMS, who said they could ft this small job into their programme during the winter.

Production thinning

Chris Maher from FOMS came out to appraise the block with myself and Sharo, and preliminary costing estimates showed that the thinning was a viable operation, giving a nett return in the order of $15 a tonne, with an estimated 75 tonnes a hectare to be produced. The harvest rate of $35 a tonne was agreed with Sharo to thin down from approximately 400 stems to 300 stems per hectare.

Export prices at the time were relatively low, with shipping rates around US$36 and the New Zealand dollar at 80 cents. However, the nett return for virtually all grades was positive, and it was identified that the forest contained a percentage of poles and post wood for local mills at relatively good returns.

The idea was that the production thinning operation would improve the stand and the revenue from the thinning would pay for the construction of access roads and skids required to service the final clear felling. These amounted to 800 metres of road to be constructed and metalled and two skid sites to be built.

A decision was made to go ahead and Chris Arcus from CCA Earthmoving was engaged to construct the roads and skids. Once the first section of road and first skid were constructed, a road was made along the  existing track to the second skid site and the 1992 stand. The thinning carried out on the 1992 stand was excellent, with good tree selection and very little damage to the final crop. Good log making ensured that poles and post wood were produced. The final results were better than forecast with 912 tonnes, or 83 tonnes a hectare, produced at an average nett return of $21.30 a tonne

Thinning then began on the 1993 stand which proved to be much trickier. The sand type was less like the grey dune sand in the 1992 stand and more a black peaty top sand which proved to be very slippery. This, along with the steeper dunes, caused the skidder to slide around with an unacceptable amount of damage to the final crop. A decision was made very quickly to abandon this part of the operation. Road construction had cost $24,600 and this had not quite been covered by the production thinning due to the 1993 stand not being production thinned. Much head scratching followed over the decision whether to do a light waste thin on the 1993 stand. In the end it was decided to leave it as it was.

Over the ensuing few years it was easy to see the marked difference in tree size between the 1992 stand which had been production thinned and the 1993 stand which had not been thinned. The difference in size of the pruned butt logs was most noticeable.

First harvest

In April 2015, I asked FOMS to give me an estimate of the return I might expect if the un-thinned 1993 stand was to be clear felled. Part of my reasoning for clear felling this area was that Transpower wanted to take out two rows of trees along the entire boundary adjacent to their transmission lines, which would have resulted in a significant number of trees being wasted.

Export prices at that time were again relatively low. Shipping and exchange rates had reduced, but the US dollar sale prices had fallen dramatically after a sustained two-year period of upward movement. Despite this, with FOMS access to local sawmills and a good range of grades, this 22-year-old stand was estimated to give a nett return of around $35.40 a tonne. A logging rate of $32 a tonne was agreed with Horowhenua Harvesting and clear felling began in May 2015. Piece size was estimated around one tonne a tree and the block had quite significant pulling distances.

With this harvest, 57 per cent of the logs went to local sawmills. Over 10 per cent were P30 pruned saw logs which could only go for export as there were no domestic pruned options for this grade. The final result was 3,994 tonnes at a nett return of $39.70 a tonne.

	Thinning at age 20		Clear fell unthinned at age 22		Clear fell thinned at age 25
Grade	Percentage recovery	JAS Conversion	Percentage recovery	JAS Conversion	Percentage recovery	JAS Conversion
P35			8%		23%
PB40	11%	0.93	4%	0.96	8%	0.97
PB30			11%	0.91
S35			5%		11%
S27			17%
M30			3%
M20			18%
Long pole	3%
Short pole	4%
Postwood	5%		6%
A	21%	0.91	9%	0.95	23%	0.98
K	32%	0.89	11%	0.91	20%	0.94
KI	11%	0.83	3%	0.91	4%	0.90
KIS	13%	0.77	5%	0.81	11%	0.82
Total tonnes	912		3994		4765
Area hectares	11		10		11
Tonnes per hectare	83		399		433
Total nett	$19,415		$158,606		$366,089
Nett dollars per tonne	$21.30		$39.71		$76.83

Felling at 25 years

During 2017 I watched with interest as the log prices increased significantly, and given the 1992 stand was now 25 years old, decided to see what sort of return I could expect if I felled now, rather than held on to age 27 or 28. The numbers from FOMS showed an estimated nett return of $76.50 a tonne and so I decided to go ahead and fell the 1992 stand.

A harvesting rate of $27 a tonne was agreed with Horowhenua Harvesting and felling began in May 2017 supervised by Blake Jones from FOMS, and was completed in early June. This harvest produced 31 per cent pruned, made up of 23 per cent P35 to Crighton’s sawmill in Levin and eight per cent P30 export pruned. The final nett result was 4,765 tonnes at an average of $76.80 a tonne.

The purists among you might see that the yield of the 1992 stand at age 25 was only 433 tonnes a hectare, but I was very happy with a return of $33,267 a hectare. It is interesting to note from the table above how the grade mix improves as the stand grows and if it is thinned. You can also see how tonnes to JAS conversions improve with the age of the forest.

Lessons learned

A multiphase ground-based harvesting operation is possible if you have good access, favourable terrain and ground conditions along with a good local contractor. Keeping in regular contact with a harvesting manager you can trust can allow you to make good decisions quickly, based on market conditions and crew availability.

There was a real focus from the FOMS staff throughout all the three harvesting phases on value maximisation. This was achieved with close supervision and liaison with the log maker.

A wide range of grade options gave skilled log makers a better chance to achieve good returns from different crop types and ages. Access to close domestic sawmills can be a real winner for returns to the owner. Do not concentrate just on the logging rate or the marketing fee when considering who to use. Look very closely at how the wood is to be cut up, where it is going and what the nett result will be.

Overall, this was a very enjoyable experience for me as a forest owner, dealing with a very professional harvesting manager in FOMS, and a very professional harvester in Horowhenua Harvesting. It was nice to be able to support a local harvesting crew and local sawmills, at the same time getting a good return for my trees.