Management of Tasmania`s Giant Trees

Management of Tasmania’s
Giant Trees
Jayne Balmer1, John Hickey2 and Timothy Leaman2
1
Department of Primary Industries and Water, Hobart, Tasmania, [email protected]
2
Forestry Tasmania, Hobart, Tasmania
Background
• Tasmania is home to the largest hardwoods in the world.
• Some 88 Giant Trees are known in Tasmania and provide the
best examples of evolutionary gigantism in flowering species.
The phenomenal height, growth rate and flammability
of these Giant Trees are evolutionary traits that enable
sclerophyll species to dominate over the climatic climax
rainforest vegetation.
• The tallest and largest individual hardwood trees are currently
a Eucalyptus regnans tree in the Styx Valley (97 m) and a
Eucalyptus globulus (368 m3) in the Esperance Valley in Tasmania.
Forestry Tasmania has responded to public
concern by:
• Preparing a policy for the protection of Tasmania’s Giant Trees
in 2002.
• Establishing a Giant Trees Consultative Committee in 2003.
• Protecting all Giant Trees on State forest either in formal
reserves or within informal reserves of 100 m radius
minimum where possible.
• Developing a Standard Operating Procedure for the
identification of Giant Trees prior to logging.
The Giant Tree Consultative
Committee provides independent
advice on the management of Giant
Trees.
Inaugural members of the Giant
Tree Committee included:
M.Brown (ecological consultant),
J.Balmer (ecologist DPIW),
M.Fountain (horticulturalist
RTBG), D.Frankcombe (retired
forester), B.Potts (geneticist, UTAS),
J.Romanski (arborist), G.Sargison
(FT) and J.Hickey (FT).
Forestry Tasmania’s Giant Tree Policy
• The tallest reliably measured hardwood was a Eucalyptus
regnans of 114 m height in Victoria in 1881 but clearance,
logging and wildfires have resulted in the temporary loss of
the tallest examples of E. regnans trees from Victoria.
• The tallest and largest eucalypts were not the subject of
Tasmania’s Regional Forest Agreement (1997) and so were
not specifically required to be reserved.
• There continues to be public interest and concern about the
conservation and management of Giant Trees in Tasmania.
Distribution of Giants by Rainfall
• GTs require rainfalls over 50 mm in the driest month and over 1000
mm per annum (ie. rainfalls that support rainforest).
Average Annual Rainfall
• Median 1260 mm
• 80% between 1130-1460 mm
• Range 960-1820 mm
Average Rainfall in Driest Month
• Median 64 mm
• 80% between 60-75 mm
• Range 53-88 mm
‘Icarus dream’, the tallest hard wood in the world (97 m) Eucalyptus regnans. Photo by Brett Mifsud
Threats
Distribution of Giants by Temperature
• GTS occur in areas subject to mild winter frosts, with mildly warm
summer temperatures
Average max temp in Feb
• Median max 20.1 °C
• Range 18.2- 21.8 °C
Average min temp in July
• Median min 0.3 °C
• Range -0.2- 2.2 °
• Forestry Tasmania will seek to identify, manage and protect
Giant Trees on State forest in Tasmania. Giant Trees are defined
as:
–trees that are at least 85 metres tall
–or at least 280 cubic metres estimated stem volume. Based
on current known examples, trees of this volume are
generally at least 5m in diameter at chest height.
To achieve this policy Forestry Tasmania’s objective is to:
•Protect currently known Giant Trees;
•Periodically remeasure known Giant Trees;
•Undertake surveys to identify any Giant Trees within coupes
in the Three Year Plan that have the potential to contain these
trees;
• Maintain registers of the 10 tallest and 10 largest volume
extant trees known on all lands in Tasmania and of the 10
tallest trees ever recorded in Tasmania;
•Promote with other forest managers a statewide tourism
strategy for Giant Tree appreciation on all tenures and
participate in its implementation.
(Forestry Tasmania 2002, www.forestrytas.com.au)
Distribution by Geology
• Most Giant Trees are on geology with soils of mod to high fertility.
(26% are mapped on geology associated with low fertility soils.)
Finding Giant Trees
Terms of Reference of the Giant Trees
Consultative Committee
1. Review of nominations and recommending on suggested names.
2. Promote protection of Giant Trees.
3. Review the criteria for Giant Trees status over time.
4. Identify cohorts of exceptional regrowth for future replacement of existing senescent
stands.
3. Encourage the development of a Giant Trees register across all land tenures.
4. Make recommendations for periodic assessments of size and health of Giant Trees.
5. Promote opportunities for access to Giant Trees for recreation and tourism.
6. Advise on Giant Trees education and promotion.
7. Promote the Giant Trees website, (www.gianttrees.com.au)
Giant Trees by Height & Species
Soil fertility Legend for Geological Codes
Low
P
Permo-Triassic sedimentary
Pf
Freshwater sandstone
Pl
Lower glaciomarine sandstone,
mudstone &/or minor limestone
Q
Quaternary sediments
Qh Alluvial sand, gravel etc
R
Sandstone, siltstone, mudstone
Moderate
Dg Granite & other granitic rocks
Ol
Limestone (Gordon Group)
Pu
Upper glacio marine sandstone,
mudstone &/or limestone
Qpt Talus & colluvial slope deposits
SD Sandstone, siltstone and shale
High
Jd
Jurassic dolerite
Distribution of Giants by Terrain
• Median 380 m altitude
• 80% between 250 - 490 m
• Range 130 m to 620 m
Giant Trees by Volume & Species
• Fire: 70 of the known GTs are
within 250 m of a forest coupe
edge. Careful fire planning and
extra protection measures
ensure that the risk to these
important and fire sensitive trees
is minimised.
• Aging: Most GTs have reached
their maximum heights and
are getting shorter as they age,
many are senescent and may not
survive another century.
• Disease: Dieback in eucalypts is
very widespread and most GT’s
exhibit some crown dieback,
perhaps due to pathogens and
insects as well as abiotic factors.
• Wind-throw: Eucalyptus
regnans and other wet eucalypts
have shallow roots and are prone
to wind fall. Half the known GTs
are within 100 m of unreserved
State forest, which if logged may
increase their exposure to wind
throw. Offsetting this is their
natural tendency to occur in
situations sheltered from extreme
winds.
• Climate change: Generations of
genetic selection have adapted
these trees to their environment,
shifts in climate may reduce their
competitive advantage.
Giant Trees prefer:
• low to mid elevations [high rainfall & mild
temps]
• NE to E aspects [more sunshine & less
wind]
• well drained, moderate slopes.
• Median 19 degrees slope
• 80% between 9 and 41 degrees slope
Damocles (E. regnans with intact crown in the centre
of the frame). Photo by Walter Herrmann
• Finding GTs within a forest of trees of
lesser stature is surprisingly difficult.
• Nearly all GTs have been found within 100 m of a road or coupe edge.
• Volunteer GT enthusiasts with their passion for discovery have had the
greatest success to date in locating GTs.
• FT uses systematic ground-based surveys to search planned coupes with
a potential to contain GTs, all forest coupes with a PI type of E1 are
checked.
• LIDAR shows potential for finding tall GTs and has already been used to
find a GT at the Warra LTER site (David Mannes pers.comm).
People who have nominated the most
Giant Trees include:
Brett Mifsud (41 trees)
Walter Herrmann (17 trees)
Bernard Plumpton (4 trees)
David Mannes
(4 trees)
Mark Bradley
(4 trees)
Lachie Clarke
(4 trees)
• Others include: J.Balmer, S.Burgess,
Blackwell, C. Bond, J.Burn, S.Clark,
M.Cohen, L.Davey, T.Greenwood,
R.Hamilton, J.Hickey, P.Kostoglou, G.Law,
J. Lawson, A.Mount, L.Nicklason, Page,
A.Robertson, M.Ryan, S.Sillett, S.Wright.
Recruitment of future Giants
Eucalyptus regnans and other wet eucalypt species
- reach their maximum heights at around 200 years of age
- have a life expectancy of between 350 and 450 years.
- need fire or other disturbance to regenerate.
Brett Mifsud with the
largest volume Eucalyptus
obliqua (363 m3), located
at Mt Cripps. Photo
courtesy of Brett Mifsud
The Giant Tree Consultative Committee intends to work with land
managers to:
• Maintain fire regimes of between 200-400 years on lands suited to the
production of GTs within formal reserves.
• Encourage managers to maintain long-term records of GT occurrences
and assess the potential for the regrowth cohorts at these sites to
produce a new generation of GTs.
• Develop a register of tallest regrowth trees in Tasmania and investigate
the opportunities to protect stands that may produce new GTs in the
future.
• Encourage research to determine the genetic, stand and site
characteristics that produce GTs.
Reserve Design & Management
• Giant Trees on State forest are informally reserved under
the Management Decision Classification (MDC) zoning
system used by Forestry Tasmania.
• The minimum reserve applied to Giant Trees in uncut
forest is a 3.1 ha reserve protecting a100 m radius area
around the tree.
– 14 trees are protected within reserve areas of the
minimum size
– 23 trees are protected within larger areas.
– 2 trees are reserved in smaller areas because they were
discovered after logging started.
– The largest MDC zone is a 67 ha reserve protecting 6
GTs along Bennetts Road.
• Many of the MDC zones protecting Giant Trees adjoin
larger reserves.
• Fire management planning aims to avoid burning Giant
Trees
– Many of the GTs have fire scars at their base, providing
evidence that they have survived past wild fires, however
they are known to be sensitive to fire.
– Most regeneration burns have successfully avoided
burning reserved Giant Trees.
– In 2003 an accidental fire escape
caused the death of one of the
largest Giants, known as ‘El Grande’.
This regrettable event contributed
to the formation of the Giant
Tree Consultative Committee
and a review of fire management
procedures.
Left: This butt scar shows that this Giant Tree
in the Picton Valley has survived fire. Photo by
Mick Brown
Right: The largest volume eucalypt in
Tasmania ( 368 m3), Eucalyptus globulus.
Photo by Walter Herrmann
Depar tment of Pr imar y Industr ies and Water
Tenure
Reserves
• Mount Field National Park , 1 GT (15,880 ha)
• Franklin-Gordon Wild Rivers NP, 8 GTs (440,390 ha)
• Reynolds Falls Nature Recreation Area, 1 GT (11,760
ha)
• Evercreech Forest Reserve, 1 GT (52 ha)
• Big Tree FR, 6 GTs (112 ha)
• North Styx FR, 6 GTs (4,224 ha)
• Styx Tall Trees FR, 21 GT’s (336 ha)
• Informal reserves protect 39 GTs (sizes range from 2
to 67 ha, the median reserve size is 4 ha).
Bronnie Kimber, Wally
Herrmann and Andy
Wakefield at the foot of
Mnemosyne (E. regnans,
16.7 m girth, 288 m3).
Photo courtesy of Walter
Herrmann
Other State Forest
• Five recently discovered GTs and 1 dead GT are in
unreserved State forest coupes. The live trees will be
protected by reservation when their Giant Tree status is
verified.
Acknowledgments
The authors would like to acknowledge the
following contributions towards this poster:
• Mick Brown for ideas developed in this poster
• Brett Littleton for the design and layout of the
poster
• Jody Bruce for running the climatic modelling
program ESOCLIM to obtain climatic data for
the Giant Tree sites
• Tim Osborn for providing data from the Giant
Tree register
• Ruiping Gao for undertaking GIS queries
• Brett Mifsud, Walter Herrmann, Mick Brown
and staff at Forestry Tasmania for providing
photographs
• Staff in the Biodiversity Conservation Branch
for assistance and advice