Estimated volumes of radiata pine in the USE

ForestrySA, through funding from AFFA and the Natural Heritage Trust, began a survey of the timber resource on private land in the Upper South East in 1998.

The mensuration strategy adopted was to:

  • not assess any plantation less than 2.0 ha;
  • visually assess plantations between 2.0 and 5.0 ha;
  • measure inventory plots on any area over 5.0 ha, plots to be 0.1 ha in size and ocularly sited on a representative site, the sampling intensity to be one plot per 6 ha;and
  • not assess any plantation less than 8 years of age at January 1998 (though these have been included in later assessments).

The general assumptions were:

  • to base predictions on a 35 year rotation;
  • to carry out first thinning at age 12+ (depending on site quality), assuming a preservation oriented first thinning; and
  • assume standard silvicultural management.

ForestrySA's yield regulation system (RADGAYM) was used to estimate volumes. This complex system predicts volumes by applying growth models to information such as tree height, diameter and age (as collected via inventory plots in 1998). The growth model used in this particular case is based on growth around the Cave Range area (10 km south of Naracoorte) and assumes rainfall of around 600-650mm. The following table shows the extractable volumes, or the volume available after waste factors have been subtracted, over the next 35 years in cubic metres.



 
YEARS

V7(m3)

V10 (m3)

V15 (m3)

V20 (m3)

V30 (m3)

V40 (m3)

2001-2005

9,495

9,042

7,352

4,843

1,181

90

2006-2010

33,679

29,430

12,080

2,598

781

108

2011-2015

22,077

19,347

8,127

1,505

306

33

2016-2020

24,114

23,791

22,656

10,892

1,016

0

2021-2025

36,182

35,942

35,175

18,103

1,966

0

2026-2030

33,307

33,272

33,155

29,494

12,512

2,118

2031-2035

159,587

159,449

159,023

145,906

61,479

10,358

Limitations of growth predictions It should be emphasized that these growth predictions have been made with some limitations. These include the use of estimated rather than assessed site quality for plantations; inventory (tree measurement data) of varied quality; uncertain records of plantation history (including plantation age, establishment practices, and timing of thinning operations); use of the yield regulation system outside it's application range (biometry, waste factors); and the unpredictability of what farmers actually decide to do with their plantations (in terms of future harvesting operations).