Hawkes Bay wood availability forecasts for the period 2007–2040
Wood availability forecasts for the Hawkes Bay
Assumptions
The wood availability forecasts for the Hawkes Bay Region are based on the following assumptions:
All the area that is harvested is replanted (with a regeneration lag of one year) except:
• 5500 hectares in the large-scale owners’ estate;
• 20 percent of the area in the small-scale owners’ estate.
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.
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 after harvest;
• in 2005–2019, 25 percent of the pruned area is replanted into the unpruned croptype after harvest. Subsequently (2020–2034) 10 percent of pruned area is replanted into the unpruned croptype.
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 and are estimates for the 2006 and 2007 years. The small-scale owners estimates in 2005–2007 are based on feedback from the major forest owners and consultants in the Hawkes Bay Wood Supply Region.
Table 1: Volumes of radiata pine harvested in 2005–2007
| Harvest year | Large-scale owners (m3) | Small-scale owners (m3) |
|---|---|---|
| 2005 | 1 234 000 | 80 000 |
| 2006 | 1 561 000 | 200 000 |
| 2007 | 1 514 000 | 160 000 |
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 (54 hectares total) were removed from the model.
Scenario 1
In this scenario, all trees are harvested at age 30, indicating the “pure” (unconstrained) availability of wood from Hawkes Bay. This means wood availability reflects the age-class distribution. Figure 2 shows the age-class distribution of radiata pine in Hawkes Bay, 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 (687 hectares) at age 17 (planted in 1988) in Figure 2. Conversely, the high point at 2024 (Figure 3) occurs because of the large area (12 161 hectares) at age 11 (planted in 1994) in Figure 2.
Figure 3 indicates that wood availability does not have the potential to increase markedly over the next 15 years.
Figure 2: Age-class distribution of Hawkes Bay radiata pine – combined estate as at 1 April 2005
Figure 3: Hawkes Bay 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’ estate
The age-class distribution of the large scale owners’ estate (Figure 4) indicates that there is a large variation in the area in age-classes. There is relatively little area in age-classes 14 to 18 years because of limited planting in 1987 to 1991. 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 Hawkes Bay 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 decline after 2008 but increase from 2015 reaching 1.5 million cubic metres per year from 2022.
Figure 5: Hawkes Bay 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 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 and 5).
Figure 6: Age-class distribution of the Hawkes Bay 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 4737 hectares planted by small-scale owners in 1992 (age 13 in Figure 6) being harvested at age 30 years.
Figure 7: Hawkes Bay radiata pine availability under scenario 2 – combined estate
Fluctuations in harvest volumes of the magnitude shown in Figure 7 would be impractical for the local industry to cope with because of marketing and logistics realities. There would not be enough harvesting capacity (harvesting crews and equipment) to cut all the volume available during the peak period, and it would be difficult to get short-term sales contracts to cover this volume.
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.
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 after 2016. The potentially available volume increases to 2.5 million cubic metres per year from 2020. 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: Hawkes Bay radiata pine availability under scenario 3
Figure 9: Average radiata pine clearfell age in Hawkes Bay under scenario 3
Scenario 4
The fourth scenario is based on a split non-declining yield, with a rotation age of 30 years. This scenario gives a forecast wood availability that is similar to scenario 3 through to 2019 (Figure 10). Wood availability has the potential to increase to 3.0 million cubic metres per year from 2021 before reducing to 2.2 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: Hawkes Bay radiata pine availability under scenario 4
Figure 11: Average radiata pine clearfell age by ownership category in Hawkes Bay under scenario 4
The total volume forecast for scenario 4 is broken down by log grade in Figure 12.
Figure 12: Hawkes Bay radiata pine availability by log grade under scenario 4
Scenario 5
Different wood availability profiles are generated if target rotation age is changed from 30 years to either 28 or 32 years (Figure 13). 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 14). No increase was assumed from 2008 to 2019 for the 32-year variation in order to get separation in harvest volumes.
Figure 13 shows that there is the potential for a significant increase in the Hawkes Bay harvest volumes by increasing the target clearfell age. However, there is a range of possibilities for both the timing of the increase and the level of the potential harvest volume.
Figure 13: Hawkes Bay radiata pine availability by target rotation age under scenario 5
Figure 14: Average radiata pine clearfell age in Hawkes Bay by target rotation age under scenario 5
Scenarios for other species: Douglas-fir
The area of Douglas-fir in Hawkes Bay is less than 1000 hectares. The age-class distribution of Douglas-fir is not uniform (Figure 15).
Figure 15: Age-class distribution of Hawkes Bay 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 is limited to an upper limit of 30 000 cubic metres per year (Figure 16).
Figure 16: Hawkes Bay Douglas-fir availability – combined estate as at 1 April 2005
Contact for Enquiries
MAF Information Services
Pastoral House
25 The Terrace
PO Box 2526
Wellington, NEW ZEALAND
Fax: +64 4 894 0721
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