sustainable forest management - Forestry Tasmania

Seed and sowing
Forestry Tasmania classifies the source of seed sown onto
harvested native areas into three categories.
On-site seed is collected from the harvested area or
immediately adjacent to it from an area that has a similar
topography, elevation, aspect, parent material and forest
type. On-site seed is highly desirable as it maintains gene
pools and ensures that regeneration is well adapted to the
site.
In-zone seed is from the same seed zone as the nominated
harvesting area. The seed zones are detailed in Native
Forest Silviculture Technical Bulletin No. 1 Eucalypt Seed
and Sowing. For the purposes of the performance indicator,
in-zone seed does not include the on-site seed component.
Out-of-zone seed is collected from outside the seed zone
of the nominated coupe. This is the least preferred seed
source. When there is insufficient on-site or in-zone seed,
the most appropriate available out-of-zone seed is selected
following the guidelines set out in Technical Bulletin 1.
The seed provenance quality standard is that each
harvested area should be regenerated with at least 10 per
cent on-site seed with the remainder being in-zone seed
matched to forest type. These seed provenance targets
need to be met for each species in the sowing mix.
In 2007/08, 3387 hectares was sown with eucalypt seed. A
total of 1435 hectares (42 per cent) of this area achieved
the seed provenance quality standard. This is a six per
cent decrease when compared with the five-year average
of 48 per cent of area achieving the standard (Figure 17).
The main cause of not achieving the desired standard was
insufficient on-site seed being available.
In 2007/08, 2,912 kilograms of eucalypt seed was sown. Of
that 31 per cent of the seed used was on-site, 62 per cent
in-zone and seven per cent out-of-zone. This compares well
with the five-year average of 40per cent on-site, 52 per cent
in-zone and eight per cent out-of-zone seed.
The quality standard for sowing operations is that the delay
between site preparation completion and artificial sowing
should be less than 21 days and shorter if possible. This is
because the best regeneration generally occurs when seed
is sown on the freshest and most receptive seedbed. In
2007/08, 91per cent of the artificially sown area achieved
this standard. This represented a five per cent decrease
on the five-year average (96 per cent). The lack of available
helicopters was the main reason for nine per cent of the
100
area not meeting the standard.
90
% of sown area meeting standard
% of sown area meeting standard
Figure 80 17. Five-year seed provenance performance by production area
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60
50
40
30
20
10
0
03/04 04/05 05/06 06/07 07/08
2003/04 2004/05 2005/06 2006/07 2007/08
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