East Coast wood availability forecasts for the period 2007–2040
Wood availability forecasts for the East Coast
Assumptions
The wood availability forecasts for the East Coast are based on the following assumptions:
- Replanting – All the area that is harvested is replanted (with a regeneration lag of 1 year).
- The area awaiting replanting as at 31 March 2005 is included as area at age 0 (the area to be replanted in the 2005 planting season).
- No new land planting is included.
- Species/Regime – Area is replanted back into the same species and regime, except that all Douglas-fir in the large-scale owners’ estate is replanted to radiata pine following harvest.
The total volumes of radiata pine harvested by large and small-scale owners in 2005–2007 are shown in Table 1. The large-scale owners’ returns are based on the harvest intentions data supplied to MAF. The small-scale owners’ estimates are based on feedback from consultants in the East Coast Wood Supply Region.
Table 1: Volumes of radiata pine harvested in 2005–2007
| Harvest year | Large-scale owners (m3) |
Small-scale owners (m3) |
|---|---|---|
| 2005 | 481 000 | 148 000 |
| 2006 | 563 000 | 129 000 |
| 2007 | 949 000 | 152 000 |
For overmature stands it was assumed that any area of radiata pine in the small-scale owners’ estate that was aged over 40 years would not be harvested, so forests aged 41 years or older (38 hectares total) were removed from the model.
Scenario 1
In this scenario all areas harvested at age 30 indicating the “pure” (unconstrained) availability of wood from the East Coast. This means wood availability reflects the age-class distribution. Figure 2 shows the age-class distribution of radiata pine in the East Coast, and Figure 3 shows the wood availability. The low point of 30-year-old trees in 2018 in Figure 3 occurs because of the small area (1450 hectares) at age 17 (planted in 1988) in Figure 2. Conversely, the high point at 2023 (Figure 3) occurs because of the large area (13 044 hectares) at age 12 (planted in 1994) in Figure 2.
Figure 2: Age-class distribution of East Coast radiata pine – combined estate as at 1 April 2005
Figure 3: East Coast radiata pine availability under scenario 1
Scenario 2
In this scenario, large-scale owners harvest in line with their stated intentions, and small-scale owners harvest trees at age 30.
Large-scale owners
The age-class distribution of the large scale owners’ estate (Figure 4) is reasonably uniform at least between ages 4 and 24. The area at age 0 is the area awaiting replanting as at 31 March 2005 (to be replanted in the 2005 planting season).
Figure 4: Age-class distribution of the East Coast radiata pine estate – large-scale owners as at 1 April 2005
For this scenario, the availability of wood from large-scale owners is based on stated harvest intentions for 2005 to 2015. Thereafter the availability is constrained to be non-declining with a target rotation age of 30 years. The wood availability of large-scale owners (Figure 5) is forecast to increase rapidly and exceed 1.6 million cubic metres per year from 2010.
Figure 5: East Coast radiata pine availability under scenario 2 – large-scale owners
Small-scale owners’ estate
The age-class distribution of the small-scale owners’ estate (Figure 6) is very irregular with over 4000 hectares in each of ages 8 to 13 years (planted in 1992 to 1997) and much less in all other age-classes. Forecasting the availability from this estate depends on how the large area in ages 8 to 13 will be harvested:
- at a fixed rotation age (scenario 2);
- spread over many years (scenario 3);
- spread over an intermediate number of years (scenario 4).
Figure 6: Age-class distribution of the East Coast radiata pine estate – small-scale owners as at 1 April 2005
Combined estate
The wood availability from all owners is presented in Figure 7. For the large-scale owners’ estate, it is the same as in Figure 5 (scenario 2 where the entire small-scale owners’ estate is assumed to be harvested at age 30). The fluctuations in the total volume harvested reflect the variation in the age-class distribution of the small-scale owners’ estate.
The large increase in volume from 2022 (Figure 7) occurs when the large areas from the small-scale owners’ estate in young age-classes (8–13) is harvested. For example, the increase in 2022 is a consequence of the 4356 hectares planted by small-scale owners in 1992 (age 13 in Figure 6) being harvested at age 30 years.
Figure 7: East Coast radiata pine availability under scenario 2 – combined estate
Fluctuations in harvest volumes of the magnitude shown in Figure 7 would be impractical because of marketing and logistics realities.
Scenario 3
The third scenario assumes a non-declining yield, with a target rotation age of 30 years. An extra constraint was modelled so the total volume could not increase by more than 10 percent annually from 2014 on.
Figure 8 indicates that when the small-scale owners’ estate is harvested to complement the large-scale owners’ estate, the total volume (of radiata pine) has the potential to increase substantially. The potential volume available increases to 3 million cubic metres per year from 2018.
This scenario is similar to the base case scenario adopted in the 2000 National Exotic Forest Description wood supply forecasts. However, it results in the small-scale owners’ estate being harvested at rotation ages that differ markedly from 30 years (Figure 9).
Figure 8: East Coast radiata pine availability under scenario 3
Figure 9: Average radiata pine clearfell age by ownership category under scenario 3
Scenario 4
The fourth scenario is based on a split non-declining yield, with a rotational age of 30 years. This scenario gives a forecast wood availability that is similar to scenario 3 through to 2018 (Figure 10). Wood availability increases to 3.4 million cubic metres per year from 2020 before reducing to 2.5 million cubic metres per year from 2037.
The main difference from scenario 3 is that the large area of young stands in the small-scale owners’ estate is assumed to be harvested over a shorter period of time. As a consequence the total volume was modelled to be non-declining from 2007 to 2034 for the current rotation. Thereafter an annual reduction of up to 10 percent was assumed, with the yield to be non-declining for the next rotation (from 2037). As a consequence the average clearfell age for small-scale owners stays closer to the target of 30 years than in scenario 3 (Figure 11).
Figure 10: East Coast radiata pine availability under scenario 4
Figure 11: Average radiata pine clearfell age by ownership category in the East Coast under scenario 4
The total volume forecast for scenario 4 is broken down by log grade in Figure 12.
Figure 12: East Coast radiata pine availability by log grade under scenario 4
In calibrating the intensively managed radiata pine yield tables to match harvest intentions, the chiplog volume was approximately halved. This reflects the limited markets for chiplogs/pulplogs that are currently within an economic cartage distance on the East Coast; so the current intention is not to extract substantial volumes of chiplogs (Figure 13 shows the scale of this). These volumes are potentially available for utilisation in the future.
Figure 13: Potential East Coast radiata pine chiplog availability under scenario 4
(The “current” volume is the same as in Figure 11 and the “additional” volume is what is potentially available in addition to the volume that owners currently intend recovering).
Scenario 5
Different wood availability profiles are generated if target rotation age is changed from 30 years to either 28 or 32 years (Figure 14). Because of the limitations imposed by the current age-class distribution and large-scale owners’ stated harvest intentions, it takes some time to achieve separation of average clearfell age (Figure 15). No increase was assumed from 2012 to 2015 (and the harvest intentions of large-scale owners were reduced) for the 32-year variation in order to get separation in harvest volumes.
Figure 12 shows that there is the potential for a significant increase in the East Coast harvest volumes. However, there is a range of possibilities for the timing of the increase and the level of the potential harvest volume.
Figure 14: East Coast radiata pine availability under scenario 5
Figure 15: Average radiata pine clearfell age in the East Coast by target rotation age under scenario 5
Scenarios for other species: Douglas-fir
The area of Douglas-fir on the East Coast is about 1800 hectares. The age-class distribution of Douglas-fir is far from uniform (Figure 16).
Figure 16: Age-class distribution of East Coast Douglas-fir – combined estate as at 1 April 2005
The Douglas-fir harvest for the large-scale owners’ estate is based on intentions for 2005 to 2015. From 2015 to 2049 clearfell volume for large-scale owners is limited to an upper limit of 50 000 cubic metres per year (Figure 17).
Figure 17: East Coast Douglas-fir availability – combined estate as at 1 April 2005
Contact for Enquiries
John Vaney
Regional Team Leader
Sector Performance Policy
Ministry of Agriculture and Forestry
PO Box 1340
Rotorua
Phone 07 921 3407
Cell 029 921 3407
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