Forests regenerate 19 Aug (Shrinked) - forestrytas.com.au

Forests Regenerate!

Mark Neyland
Native forest research officer

Forestry Tasmania

19 August 2005

Forests Regenerate!

• Wet forest silviculture -
clearfell, burn and sow

• Alternatives to clearfell, burn and sow -
the Warra Silvicultural Systems Trial

• Eucalypt regeneration following
alternative treatments

Wet eucalypt forest silviculture

• Wet eucalypt forests
have a closed
understorey of tall
shrubs.

• Slash loads arising from
harvesting are high and
an impediment to
regeneration.

Wet eucalypt forest silviculture

• Traditional silviculture
in wet eucalypt forest
was clearfell, high
intensity burn and sow.

• Safe, economic, and not
good to look at!

Wet eucalypt forest silviculture

• But effective!
• Five year old

regeneration on a cable
harvested coupe.



% Area which achieved Regeneration success
standard
100
90
80
70
60
50
40
30
20
10
0
1998/99 1999/00 2000/01 2001/02 2002/03 2003/04

Reporting Year

Problems with clearfelling

• Initial visual impact
• Smoke nuisance
• Structural simplification
• Reduction in rainforest species, rotting

logs, hollow-dependent birds and
mammals
• Reduction of special species timbers
and leatherwood nectar

Alternatives to ‘clearfell, burn
and sow’silviculture are being
trialled at the Warra SST



Treatments

• Clearfell burn and sow with understorey
islands

• Dispersed retention (10%)
• Aggregated retention (30%)
• Strip-felling
• Single tree/small group selection

Clearfell, burn and sow with
understorey islands

• Control coupe - plus understorey
islands - comparison with alternatives

• High intensity burn
• Aerially sown with on-site seed

Clearfell, burn and sow with
understorey islands

What are understorey islands?

• 40 m by 20 m patches
retained undisturbed
during the harvesting.

• Overstorey eucalypts may
be retained (as pictured)
or felled, if this can be
done without disturbing
the understorey in the
island.



Dispersed retention

• 10% of the original forest retained as
evenly dispersed trees

• Improved aesthetics
• Retained habitat and biodiversity
• Potential supply of larger logs
• Natural seedfall
• Safety issues

Dispersed retention



Aggregated retention

• 30% of the original forest retained
• Improved aesthetics
• Retained habitat and biodiversity
• Potential supply of larger logs
• Improved mixed forest regeneration
• Natural seedfall

Aggregated retention



Strip-felling

• 50% of the original forest retained for
half the rotation

• Improved aesthetics
• Improved mixed forest regeneration
• Retained habitat
• Natural seedfall

Strip-felling







Single tree/small group selection

• Harvest 40 m3/ha every 20 years
• Improved special species timber supply
• Retained habitat
• Natural seedfall
• No burning

Single tree/small group selection





Regeneration success - percentage of plots stocked

% of plots stocked 100

Stocking age 1

90

Stocking age 3

80

Stocking standard - 65%

70

60

50

40

30

20 Clearfell, burn and sow Stripfells Dispersed Aggregated SGS
retention retention
with understorey islands

10

0
8H 8B 1AN 1AL 1B 8C 1E 8I 5D

Coupe/Treatment

Height growth at age 1 and 3

250

200

Height (cm) 150

100 SGS

Clearfell, burn and sow Stripfells Dispersed Aggregated
with understorey islands retention retention

50

0
8H 8B 1AN 1AL 1B 8C 1E 8I 5D

Coupe/Treatment

Conclusions

• Clearfell, burn and sow produces excellent
regeneration but at a cost

• Aggregated retention holds promise of
delivering good regeneration but it is too
early to be sure

• Aggregated retention coupes are being
developed with the districts and are being
monitored for regeneration - practice
makes perfect!

Thanks to

Leigh Edwards, John Hickey, Joanne
Dingle, Shannon Clark, Bernard
Plumpton, and our many helpers with
regeneration surveys.