December 2000 vol 3 no 2 ISSN 1441-1288 Forest Practices news published by the Forest Practices Board, 30 Patrick Street, Hobart – Tasmania – 7000 phone (03) 6233 7966; fax (03) 6233 7954; email [email protected] – www.fpb.tas.gov.au Articles from this newsletter may be reproduced. Acknowledgement of the author and Forest Practices Board is requested. The views expressed in this newsletter are not necessarily those of the Forest Practices Board Release of the new Forest Practices Code Board and Council .............. 2 Resources .......................... 3 The Black Box .................... 3 Noticeboard ....................... 5 Features ............................ 7 Flora ............................... 11 Soils ............................... 13 Geomorphology ................ 17 contents The new Forest Practices Code was officially launched by the Deputy Premier and Minister for Infrastructure, Energy and Resources Paul Lennon on Friday 24 th November 2000. In releasing the Code, Mr Lennon said that the Forest Practices Code is an integral part of the delivery of sustainable forest management at the operational level. Mr Lennon said that the new Code contains a large number of refinements and new guidelines. The key amendments update the provisions of the Code in accordance with new information, legislation and policies, including the Regional Forest Agreement. The new code provides more guidance with respect to fire management, the establishment of plantations within previously cleared streamside reserves, and the conservation and management of natural values. It introduces a new requirement for notification and consultation with neighbours and local government prior to the commencement of operations, and it requires that consideration be given to minimising any adverse effects of plantations on neighbours. The Minister said that these measures, along with other initiatives such as the Good Neighbour Charter, will help to effectively deal with many of the issues that arise between neighbours when forestry operations are being planned and conducted. The Chair of the Forest Practices Board, Ken Felton, said that the new Code results from extensive independent reviews and public submissions. Mr Felton said that over 70 submissions from the public, scientists, landowners, forest industry and conservation interests were received and considered by the Forest Practices Board in drawing up the new Code. Mr Felton paid particular thanks to the efforts of the many Forest Practices Officers and forest practices specialists who made contributions on changes to the Code, and to the efforts of the Forest Practices Advisory Council, Forest Practices Board, Chief Forest Practices Officer and Forest Adviser Chris Mitchell who coordinated the review process. Tasmania’s Chief Forest Practices Officer Graham Wilkinson said that the amendments to the Code maintain Tasmania as a world leader in best forestry practice. Mr Wilkinson said that our innovative and progressive forest practices system continued to attract great interest at a national and international level. However, he said that we do not intend to rest on our laurels. The forest practices system is based upon a principle of continuing improvement. Supporting the new Code will be ongoing training, education, research and review, particularly in the areas of maintaining water quality and biodiversity. Mr Wilkinson said that it was particularly pleasing to note that the forest companies and Forestry Deputy Premier, Paul Lennon, and Chair of the Forest Practices Board, Ken Felton, at the launch of the new Forest Practices Code.
Transcript
1 Forest Practices News vol 3 no 2
December 2000 vol 3 no 2 ISSN 1441-1288
Forest Practices
newspublished by the Forest Practices Board, 30 Patrick Street, Hobart – Tasmania – 7000
phone (03) 6233 7966; fax (03) 6233 7954; email [email protected] – www.fpb.tas.gov.auArticles from this newsletter may be reproduced.
Acknowledgement of the author and Forest Practices Board is requested.The views expressed in this newsletter are not necessarily those of the Forest Practices Board
Release of the new ForestPractices Code
Board and Council .............. 2
Resources .......................... 3
The Black Box .................... 3
Noticeboard ....................... 5
Features ............................ 7
Flora ............................... 11
Soils ............................... 13
Geomorphology ................ 17
contents
The new Forest Practices Code was officially launched by the Deputy Premier and Minister forInfrastructure, Energy and Resources Paul Lennon on Friday 24th November 2000. In releasing the Code,Mr Lennon said that the Forest Practices Code is an integral part of the delivery of sustainable forestmanagement at the operational level.
Mr Lennon said that the new Codecontains a large number ofrefinements and new guidelines.The key amendments update theprovisions of the Code inaccordance with new information,legislation and policies, includingthe Regional Forest Agreement.The new code provides moreguidance with respect to firemanagement, the establishment ofplantations within previouslycleared streamside reserves, andthe conservation and managementof natural values. It introduces anew requirement for notificationand consultation with neighboursand local government prior to thecommencement of operations, andit requires that consideration be
given to minimising any adverseeffects of plantations onneighbours. The Minister said thatthese measures, along with otherinitiatives such as the GoodNeighbour Charter, will help toeffectively deal with many of theissues that arise betweenneighbours when forestryoperations are being planned andconducted.
The Chair of the Forest PracticesBoard, Ken Felton, said that thenew Code results from extensiveindependent reviews and publicsubmissions. Mr Felton said thatover 70 submissions from thepublic, scientists, landowners,forest industry and conservationinterests were received andconsidered by the Forest PracticesBoard in drawing up the newCode. Mr Felton paid particularthanks to the efforts of the manyForest Practices Officers and forestpractices specialists who madecontributions on changes to theCode, and to the efforts of theForest Practices Advisory Council,Forest Practices Board, ChiefForest Practices Officer and ForestAdviser Chris Mitchell whocoordinated the review process.
Tasmania’s Chief Forest PracticesOfficer Graham Wilkinson saidthat the amendments to the Code
maintain Tasmania as a worldleader in best forestry practice. MrWilkinson said that our innovativeand progressive forest practicessystem continued to attract greatinterest at a national andinternational level. However, hesaid that we do not intend to reston our laurels. The forest practicessystem is based upon a principleof continuing improvement.Supporting the new Code will beongoing training, education,research and review, particularlyin the areas of maintaining waterquality and biodiversity. MrWilkinson said that it wasparticularly pleasing to note thatthe forest companies and Forestry
Deputy Premier, Paul Lennon, andChair of the Forest Practices Board,Ken Felton, at the launch of the new
Forest Practices Code.
c-grove
Typewritten Text
Trim 2010/129578
2Forest Practices News vol 3 no 2
Board and Advisory Council reportsGraham Wilkinson, Chief Forest Practices Officer
Annual ReportThe Board’s Annual report hasbeen submitted to Parliament andafter tabling will be circulated toForest Practices Officers andothers. The Report provides agood snapshot of the operationsof the Board, including interestingstatistics on forest practices plansand the maintenance of thepermanent forest estate, andsummaries of the research andadvisory work done by thespecialists. The results of the auditare also provided. With respect tothe audit, the Board noted thatvery high standards had beenachieved across most areas, butthere were some problem areaswhere the nominated standardwas not achieved. In particular,the Board noted problems withsome site preparation standardson State forest. The Board expectsthat the new Code will provideclearer guidelines for plantationestablishment. FPOs are asked tocontact a soils specialist if in doubtabout any of the site preparation/cultivation requirements of theCode.
Awards for excellenceMost readers would be aware thatthe Board assesses the standard ofplanning and implementation offorest practices primarily throughthe audit process. It is a credit tothe forest practices system thatForest Practices Officers andcontractors maintain very highstandards. The Board hasendorsed a proposal to recogniseexcellence in the planning and
conduct of forest practices.Industry representatives haveindicated strong support, and theCFPO will work closely withindustry representatives toprogress the concept.
The Board noted the retirement ofthe following Forest PracticesOfficers during the year. The Boardthanks these officers for their greatcontribution to the forest practices
Name Appointment OrganisationStephen F Walker FPO (Planning) Forest Enterprises TasmaniaAndrew Bennet FPO (Inspecting) Forestry TasmaniaEdward Willis FPO (Inspecting) Forestry TasmaniaHenry C. H. Chan FPO (Inspecting) Forestry TasmaniaRobert L Onfray FPO (Planning) North Forests BurnieRussell D Madeley FPO (Planning) North Forest ProductsDavid M. Bower FPO (Planning) Private Forests TasmaniaMelissa J. Syme FPO (Planning) North Forests BurnieJustin T. Cashion FPO (Inspecting) Forestry TasmaniaBrent D. Donaldson FPO (Planning) Forestry TasmaniaArthur M. Lyons FPO (Planning) Private Forests TasmaniaIan J. Brumby FPO (Planning) Forestry TasmaniaClint M. Webb FPO (Planning) North Forest ProductsDean A. Sheehan FPO (Inspecting) Forestry TasmaniaAlistair J. Hayward FPO (Planning) RayonierFrank Bishop FPO (Inspecting) Forestry TasmaniaRobert M. Young FPO (Inspecting) Forestry TasmaniaBernard S. Plumpton FPO (Planning) Forestry TasmaniaMichael G Briggs FPO (Inspecting) Forestry TasmaniaMarcel K Griffiths FPO (Inspecting) Forestry TasmaniaVanessa N Thompson FPO (Planning) Forestry TasmaniaJohn B. Hewitt FPO (Inspecting) North Forest ProductsJodie M. Frank FPO (Planning) North Forest ProductsPaula C. Sheehan FPO (Inspecting) Norske SkogAnthony J Allwright FPO (Inspecting) Forestry Tasmania
Tasmania were providing fundingfor continuing research into theprotection of streams and themaintenance of biodiversity.
Mr Wilkinson said that the Boardwould be conducting briefings onthe new Code for all ForestPractices Officers and other forestry
staff throughout November andDecember. He said as a matter ofhigh priority the Board would beusing these briefings to work closelywith Forest Practices Officers andtraining personnel to get started onan active training and educationprogram for forest contractors,landowners and interested bodies.
The new code legally takes effect on
1st January 2001.
Copies of the code are availablefrom forest companies, ForestryTasmania, the Forest PracticesBoard and Service Tasmania outletsthroughout the State.
Appointment of Forest Practices OfficersThe Board was pleased to appoint the following persons as FPOs during1999/2000. The Board thanks these officers for accepting theresponsibilities of a Forest Practices Officer and wishes them well intheir important role as part of Tasmania’s forest practices system.
system and wishes them all thebest for the future.
Training in conducting fieldsurveys for Aboriginalarchaeological sites
Forest botanyand plantidentification(F.Duncan)
5 Dec. 2000
6 Dec. 20007 Dec. 2000
1 day Seven MileBeachHollybankBurnie
Flora of Tasmania, Tasmanianeucalypts, identification of treesand shrubs, forest types, effectof forest practices, conservation
Forest PracticesCode (C.Mitchell)
Early Dec.2000
½ day Variouslocations
Briefings to all FPOs on changesto FP Code following issue of FPCode 2000
Fauna values andforest manage-ment (S. Munks)
Feb./March2001
3 days 1 in south, and1 in NW
Train FPOs in procedures forthreatened species
Forest PracticesManager training(C.Mitchell)
March. 2001 2 days To be confirmed Update forest managers onrequirements of the forestpractices system
Risk assessment(C.Mitchell)
March. 2001 1 day To be confirmed Train selected FPOs to completea safety risk assessment for treesretained under the FP Code
Karst (K.Kiernan) To beconfirmed
1 day To be confirmed Train FPOs who work in karstareas on fauna, cultural heritageand geomorphologicalrequirements
Forest practicestraining 1
Approx. May2001
4 day Orford? General training in forestpractices for FT supervisors
Forest PracticesOfficer course 2
Winter/Spring 2001
12 day Variouslocations
Pre-requisite course forappointment as FPO
1 Dependent on demand2 Two courses will be run if there is sufficient demand
CorrectionSmall streams – a progressreport on new research
In the caption to figure 1 forthe above article, publishedin Forest Practices News,August 2000, it was stated“Sarah Bunce’s honoursproject, entitled ChoosingIndicators of Class 4 StreamImpacts, is funded by theFIAT/Forestry Tasmaniaforest practices researchfund.” This is incorrect. Theproject is jointly funded byNorth Forest Products andthe RFA Trust Fund. The erroris regretted.
Interesting and varied reading in this issue with the release of the
New Forest Practices Code taking top billing. Forest Practices
Officers also get a couple of additional Christmas presents this year
with the release of the revised Threatened Fauna Manual and the
updated Forest Botany Manual, as well as Michael Laffan’s guide
for assessing soil erodibility.
We’d like to thank you for your support for FPN throughout the
past year, and for your contributions. Please keep them rolling in
– this is YOUR newsletter. Many thanks also to David Hinley for
his sterling efforts with production of FPN.
4Forest Practices News vol 3 no 2
ResourcesRevised Threatened Fauna Manual
Mark Wapstra and Sarah Munks, Forest Practices Board
The Forest Practices Board has released the latest version of the Threatened fauna Manual for Production Forestsin Tasmania (Revised November 2000 version).
This version has been madeavailable on-line to give FPOsaccess to the most currentthreatened fauna site data. AllFPOs have been issued a passwordto access the on-line servicesprovided through the FPB website (www.fpb.tas.gov.au),including the Threatened FaunaManual. Mapsheet and speciesprofiles accessed in this mannercan be considered current as of theday it is viewed. Hard copyversions of the manual have beensupplied to most District Officesand companies. Hard copies willbecome rapidly out-of-date but
can be kept current by accessingthe updating facility on the webpage. All older versions of themanual must be removed fromyour current Threatened faunamanual folder and replaced withthis latest version.
Zoology Program web siteThe Zoology Program of the ForestPractices Board has developed itsweb site (as part of the FPB website). The on-line version of theThreatened Fauna Manual can beaccessed through this page. It alsoincludes the Fauna Technical Noteseries, information on courses/
training, information on currentresearch projects and more. Weurge everyone to have a look at thesite. Please tell us how we canimprove the site and any particularinformation you would like added.All Fauna Liaison Officers shouldmake a habit of regularly usingthe site as we will be posting newinformation and field dayinformation on it rather thansending out letters by snail mail.
Brooke Craven and Fred Duncan, Forest Practices Board
As an early Christmas present to FPOs this year we will be releasing the updated Forest Botany Manual inDecember.
The new manual is in a differentformat to the regional manualsyou are used to. The seven regionshave not changed, but additionalinformation has been included tocomply with RFA requirementsand further aid field workers inrecognising botanical values.
A separate module (Module 1General Issues) gives a generalbackground and provides broadprescriptions for Statewide floraissues relating to forest operations.They include: minimising theeffects of forestry on nativevegetation, includingmanagement for weeds anddiseases (e.g. Phytophthora);recognising and managingsensitive sites (e.g. relictrainforest); reserve design andregeneration strategies.Additional information is given
on legislation relating to forest flora;RFA priority communities (andhow these relate to floristiccommunities); and recognition ofold growth forest (which generallyhas a higher conservation valuethan regrowth forest). Referencesdealing with Tasmanianvegetation and plant identificationare also included.
The seven regional modules havemaintained the layout of keyingout floristic communities on thebasis of the presence or absence ofcommon species, and theequivalent RFA community isadded as a new column in thelook-up table of conservationpriorities and communitydistribution. Therefore the RFAcommunity does not need to bekeyed out separately. Priorityspecies (mainly listed on the
Threatened Species Protection Act) arelisted by forest type. Sites which arepotentially significant for floravalues are included as before,although some of these havechanged due to changes in thereservation status of some speciesand communities.
A new module has been added tohelp FPOs to recognise common(and uncommon) forest speciesmore easily. Thanks to technologyand the scanner we have at FPB,we have been able to scan in freshmaterial, pressed plants, linedrawings and photographs ofmany Tasmanian plants. Thesewill become available on CD and/or on the WEB in the near future.This should make keying outcommunities easier and allow youto learn more plants if you are
to page 7
5 Forest Practices News vol 3 no 2
UNITED STATES CIVIL SERVICE COMMISSION.
DEPARTMENTAL SERVICE —— FOREST RANGER EXAMINATION.
DEPARTMENT OF AGRICULTURE.
Competitor must fill these blanks. Time commenced ________.
Date ______________________________
Examination No. Time finished __
Place of Examination
FIRST SUBJECT - PRACTICAL QUESTIONS
Question 1. On what Forest, or Forests, do you desire appointment as a Forest Ranger? Give general description of one of these Forestsdescribing (a) topography, or lay of the country; (b) the kind of Forest, giving the common names of principal merchantable trees; (c) thelogging operations, their extent and importance; (d) the stock industry, showing the extent and nature of the range; (e) the principalsettlements in or near the Forest, (f) In your opinion what was the main reason for creating this Forest?Question 2. (a) Describe in detail logging in a locality with which you are familiar, covering all operation, from felling the tree to deliveryof logs at the sawmill, using all ordinary names applied to the men, operations, and implements, (b) Describe a sawmill with which you arefamiliar and describe how the logs are made into lumber.
Question 3. What are the ordinary specifications of railroad ties, mining stull, lagging, fence posts? What is a cord of wood? A board foot?How are telephone poles generally measured? How are logs scaled? Name a log scale in common use in your locality and give the contentsof logs of the following sizes by this scale:• 16 feet long and 26 inches in diameter small end
• 18 feet long and 30 inches in diameter small end
• 24 feet long and 18 inches in diameter small end
• 12 feet long and 15 inches in diameter small end
Question 4. What are the dimensions of a township? Section? Quarter section? A forty? A square acre? How many links in a surveyor’schain? How many feet? How many chains in a mile? How many acres in a tract of land 600 feet wide by 3960 feet long?
Question 5. State how you would construct a 14 by 18-foot log cabin? Give the amount of material necessary and approximate cost ofconstruction.
Question 6. (a) Enumerate the articles of food and give the amount of each which you would take with you on a two-weeks’ trip in August,considering that you were entirely dependent on the supplies you took with you. (b) How many pounds can the average horse pack for sixconsecutive days, making 15 miles per day? How many pounds can the average man pack under the same conditions?
Question 7. (a) Describe a method of handling range cattle in a district with which you are familiar. Range sheep. (b) Describe by diagramfour brands and four earmarks and give the name by which each is known.
Question 8. What constitutes valid residence on a homestead claim? What are the improvement and cultivation requirements and underwhat conditions can patent be obtained under the timber and stone act, the desert land act, and the placer mining laws?
Question 9. How and for what purposes are National Forests created? How do they affect the water flow, agriculture, lumbering, grazing,and mining?Question 10. What are the chief duties of a Forest Ranger? Give a plan for protecting a specified tract of land against fire. How would youfight a fire on this tract if it had a good start?
SECOND SUBJECT - FIELD TEST
Question 1.Saddle and bridle a horse. Ride a quarter of a mile and return (a) at a trot, (b) at a gallop. Time and manner of saddling and unsaddlingto be taken into consideration by the examiner.
Question 2. Pack a horse with a tent, two blankets, one-man cook outfit, axe, and shovel, and sufficient grain or provisions to make anentire pack weigh 150 pounds. No paniers to be used. Any satisfactory hitch to be accepted. (Rate on familiarity, neatness, and dispatch,and also experience as determined by oral questions. Competitors should not be allowed to watch the examination of other competitors.)
Question 3. Estimate by pacing, the distance around a triangular tract of not less than one-half mile, giving the distance in rods, yards, andfeet.Question 4. Set up a compass, and allowing for the variation given by the examining officer, indicate east, north 25 degrees west, south 50degrees east. Take the bearing of a designated object and give the compass reading.
Question 5 . Run a compass line around a designated area and read and record the courses, allowing for the variation as given by the examiningofficer.
I hereby certify that the above-named competitor neither gave nor received assistance during his examination, and that ratings given byme are equitable and just, to the best of my knowledge and belief,
(Signature of examiner) Date _________, 190
NoticeboardCan You Pass the 1908 Forest Ranger Exam?
This is the text of the examination given to prospective Forest Service rangers in 1908, as shown in the ForestHistory Society’s online archives, www.lib.duke.edu/forest/ . Would the fledgling agency have hired you?
6Forest Practices News vol 3 no 2
Season's greetings from the Forest Practices Board
... and a new arrival – James Wapstra
7 Forest Practices News vol 3 no 2
Features
interested. This module will becontinually updated as we collectmore specimens, so if we don’thave a plant you are after, ask usagain in a few months (or checkthe web site - hopefully we willhave the capacity to continuallyupdate this).
Please feel free to scan plants youwant identified and send themdown to us for confirmation atany stage. And if you don’t mind,we may even use them to add toour own collection of scans! We
will also have access to pictures ofmany threatened species. So if youare going to assess a coupe and theCONSERVE report comes up witha threatened plant, contact us andwe’ll send you a picture if we haveone.
One day training courses on theuse of the Manual will be held inJanuary. FPOs will be notified ofdates well in advance.
So thanks to everyone who hascommented on the Manual duringits draft stages. Please pass on any
further comments you havewhile using the Manual (e.g.mistakes, suggestions forimprovement). We may be ableto provide supplementaryinformation where requested,and improvements or changescan be incorporated intoupdates.
One of the commitments of the Regional Forest Agreement (RFA) was to establish a Comprehensive,Adequate and Representative (CAR) Reserve System for Tasmania’s forests. It was recognised that a CARReserve System could not be reached relying only on public land. Consequently, to complement the RFA,the Private Forest Reserves Program (PFRP) was initiated in 1998. The Program is run through the Dept. ofPrimary Industries, Water and Environment (DPIWE). The objective of this unique program is to protect CARvalues on private land by the voluntary participation of private landowners in the CAR Reserve System.
Robbie Gaffney and Esme Atkinson, Private Forests Reserves Program
The PFRP may purchase privateland, enter into a managementagreement with the landowner, orideally, place a covenant inperpetuity on the land. In returnfor landowners participating in theProgram, incentives may beoffered, such as up front paymentand/or funding to construct andmaintain fences and weed control.
To date 362 properties coveringapproximately 70,000 hectareshave been assessed by theProgram. A total of 55 properties,covering over 10,000 ha of priorityforest, have been approved by theProgram’s Advisory Committeefor covenanting, managementagreement or purchase. Currently5,594 ha of private forest has beenprotected, through sevencovenants (2,400 ha), and elevenproperties have been purchased(3,194 ha). The Program iscurrently in the process ofcovenanting nineteen other
properties (5,285 ha).
The ProcessReferralProperties are referred to the PFRPfrom many sources including:expressions of interest fromlandowners; investigations byPFRP staff or other DPIWE staff;BushCare, Local Government andPrivate Timber Reserveapplications. The Forest PracticesSystem also has a significant rolein referring properties to theProgram, either directly throughForest Practices Officers orthrough the Forest Practices Boardspecialists. Most referrals havebeen from expression of interestby landowners and from knownareas of high conservation priorityforest. The following tableindicates the percentage of privateland referrals to the Program fromvarious sources.
BushCare 10%DPIWE/PFRP 33%Expression of Interest 32%Forest Practices Plans 22%Local Government 2%
AssessmentAfter referral, ConservationOfficers from the PFRP undertakebiological assessments on aproperty containing potentiallysuitable forest areas. Reports onthe assessment are presented to aScientific Advisory Group thatdetermines whether the areas meetthe Program’s objectives.
NegotiationsOnce the Scientific AdvisoryGroup approves a property, anindependent negotiator isappointed to liaise with the ownerto try to achieve a successfuloutcome for the PFRP. Negotiatorscome from a range of backgroundsincluding forestry, agriculturalscience, the rural sector andconservation biology.
continued next page
8Forest Practices News vol 3 no 2
ApprovalsHaving negotiated a mutuallyagreeable covenant and operationsplan with the owner, the Programthen submits the proposal to theAdvisory Committee for approval.It should be noted that the ForestPractices Board is represented onboth the Scientific Advisory Groupand the Advisory Committee. The
Committee then makesrecommendations, to both theState and CommonwealthMinisters for the Environment, onthe suitability of the proposal forfunding approval. Onceministerial approval is given,funds can be made available to thelandowner on finalisation of thelegal documents.
Priority Forest CommunitiesThe program is targeting a rangeof forest communities and priorityspecies across the state. Thecommunities have varying levelsof priority depending on theircurrent distribution or the extentof clearance since Europeansettlement. Two criticallyendangered forest communitiesthat are being targeted by the PFRPare wet Eucalyptus viminalis forestsand E. ovata forests. These foresttypes have been extensivelycleared and consequently onlyoccur in very localised remnants.
Other high priority forest typestargeted by the PFRP includeinland E. amygdalina forest, inlandE. tenuiramis forest and E.brookeriana forest. Over the past200 years, inland E. amygdalinaforest has undergone extensiveclearing and modification foragriculture, leaving scatteredremnants through the Northern
Midlands. This vulnerable forestcommunity is often host to manyrare and threatened species,reflecting the change in land usesince European settlement. Manyremnants suffer from gradualdeterioration through over-grazing, firewood cutting,inappropriate fire frequency, weedinvasions (particularly gorse) andcontinued land clearing.However, there are some remnantsin good condition as a result ofsensitive management bylandowners. These remnants areespecially important and providehabitat for many plant and animalspecies of conservationsignificance.
The PFRP has contacted manylandowners in the NorthernMidlands region that have areasof inland E. amygdalina forest ontheir properties. Currently,discussions are continuing with
several landowners that haveshown interest in the Program. Theprocess of negotiating thecontinued use of the land whilemeeting the conservationrequirement of the Program isoften time-consuming.Nevertheless, some owners in thearea have entered into covenantswith the Program while others arein various stages of consideringtheir interest in the Program.
In addition to negotiating variousmanagement agreements andcovenants with landowners, thePFRP has purchased several keyareas in the northern Midlandscovering about 800 ha ofparticularly high conservationsignificance. The three areas,Diprose Lagoon, Powranna Roadand an extension to the existingTom Gibson Nature Reserve,provide important habitat for theTasmanian bettong as well asmany rare and threatened plantspecies. Some of the significantplant species occupying thesenewly created reserves includeBrunonia australis (bluepincushion), Pultenaea humilis(dwarf bushpea), Glycine latrobeana(clover glycine) and Caladenialindleyana (Lindleys’ spiderorchid).
Other important purchases includeseveral adjoining properties innorthern Tasmania that are habitatto one of Tasmania’s rarest endemicplants, Tetratheca gunnii. Thisspecies is only found on serpentinederived soils in the Beaconsfieldarea.
The Program has also recentlymade a joint purchase of an area innorth-western Tasmania primarilyfor the protection of Eucalyptusbrookeriana forest. The area, knownas Seventeen Mile Plain, wasjointly purchased through theNational Reserve System and thePFRP. The forest included thelargest known areas of old-growthE. brookeriana forest as well as
Figure 1: Eucalyptus rodwayi forest in the Elizabeth River Catchment
Features
9 Forest Practices News vol 3 no 2
Featuressignificant areas of blackwoodswamp forest. To ensure a viablereserve area it was paramount thatassociated moorlands andheathlands were also protected, tominimise the potential for anyalteration to the plain (e.g.draining) which would affect thehydrology of the surroundingforest. The moorland and heathland
Figure 2: Buttongrass moorland with E.brookeriana forest at Seventeen Mile Plain
This addition to the State Reservesystem protects habitat for severalrare and threatened fauna speciesincluding the keeled snail,Northwest velvet worm, greygoshawk, wedge-tailed eagle,eastern quoll and spotted-tailedquoll. The reserve alsoincorporates the Montagu Caves.Apart from significant karst
features, the cavescontain bone deposits ofextinct megafaunaincluding the giantkangaroo, giantwallaby, giant echidnaand marsupial lion.These species existedduring the last ice ageand the bone depositsare at least 10,000 yearsold.
While the PFRP has made severalkey purchases, the principleobjective of the Program is to enterinto partnerships with landownersthrough establishing covenantsand management agreements ontheir land. The Program hasgenerated significant interest inrecent months and is in the processof finalising covenants andagreements with otherlandowners. Interest in theprogram is continuing to grow andthe unit has recently advertisedfor additional staff to meet thedemand.
Advantages of heapingBob Knox; Forestry Tasmania and Peter McIntosh; Forest Practices Board
High heaping using an excavator is a cost effective option to windrowing in pine forests, if clearing isrequired. Heaping has several advantages.
(1) It results in minimal mixing ofsoil with logs and woodydebris, so that the heaps canbe burnt cheaply with 100%removal;
(2) There is very little soildisturbance or compaction;
(3) There is no barrier to machinetraffic in subsequent thinningor clearfelling operations;
(4) It is easier on machinesworking amongst the densestumps.
The same technique has been usedin eucalypt forest with smallerstumps and light to moderate slashloads. Stumps are put high in theheaps. The costs are slightly higherthan windrowing, but there is noloss of plantable area – 100% siteproductivity can be achieved.Burning is very intense, but can bedone in safe conditions at low cost.
Heaping of slash on a State Forest plantation near Nietta during preparation forthe second rotation. Photograph by Peter McIntosh.
The fauna is of global importance,and was recently the focus ofattention for experts visitingTasmania from the United States,Switzerland, Sweden and Italy.These researchers were interestednot only in the crayfish themselves,but also in the management actionsthat have been and are beingdeveloped to protect these speciesfor the future.
Recovery Plan for Tasmania’s Threatened Burrowing CrayfishNiall Doran, Biodiversity Unit, DPIWE
Tasmania has a varied and interesting range of freshwater crayfish, belonging to the four native genera listedbelow. These contain the largest freshwater crustacean in the world (Astacopsis gouldi), and the most land-adapted crayfish in the world (Engaeus spp).
Astacopsis gouldi is listed asVulnerable under both theTasmanian Threatened SpeciesProtection Act 1995 (TSPA) and thenew federal Environment Protectionand Biodiversity Conservation Act1999 (EPBCA). The genusParastacoides is currently underrevision, and some of the lesscommon species may qualify forlisting under these Acts in future.At the moment, however, all fourof the burrowing crayfish specieslisted or recommended for listingin Tasmania belong to the genusEngaeus, as follows:
Genus No. of Species inTasmania
Status of those found in Tasmania
Astacopsis 3 Native, all endemic (1 listed species)Engaeus 15 Native, 13 endemic (4 listed species#)Parastacoides* 14-15 Native, all endemic (no listed species)Geocharax 1 Native, endemic (no listed species)Cherax ?? Illegally introduced (pest species)# = the listing of one of these is currently being finalised* = under revision
Species Common name Status (TSPA) Status (EPBCA)E. spinicaudatus
Scottsdale burrowingcrayfish
Recommended forupgrading toEndangered
Nominated asEndangered**
E. yabbimunna Burnie burrowingcrayfish
VulnerableNominated asVulnerable**
E. orramakunna Mount Arthurburrowing crayfish
VulnerableNominated asVulnerable**
E. martigener Furneaux burrowingcrayfish
Recommended forlisting as Vulnerable
Nominated asVulnerable**
** These nominations were originally made under the Endangered Species Protection Act 1992, but arenow being updated to match the new EPBCA criteria.
All four species are endemic toTasmania and have highlyrestricted distributions. Thecommon names reflect thegeographic areas in which theyare found. Engaeus martigener isonly found in limited areas at highaltitudes on Flinders and CapeBarren Islands, while detaileddistributional information for theother three species can be found in
the Forest Practices Board’sThreatened Fauna Manual forProduction Forests in Tasmania.These three species have allpreviously been identified asPriority Species requiring recoveryaction under the TasmanianRegional Forest Agreement 1997.
Engaeus crayfish can be found instream sides, seeps, marshy pansand boggy areas, including somewhich are surprisingly dry or freeof running water. Habitat caninclude undisturbed rainforest,
wet and dry eucalypt forest, pineplantation (particularly if anyriparian vegetation is present),cleared plantation, pasture land,road culverts and cuttings, and soon. Habitat requirements aregoverned by water quantity andquality, and the presence andquality of soil and native riparianvegetation (for shelter and food).The crayfish are good diggers, and
their burrows canoften be detected bychimneys of pelletedsoil at the entrances ora large number ofholes in the ground.Burrowing crayfishplay an important rolein soil turnover andthe recycling of deadwood and other
materials within the ecosystem.
Threatening processes includeurban and industrial pollution,inappropriately managedagricultural and forestry activities,long term fire effects, clearanceand removal of native vegetation,sedimentation, waterwaydisturbance and the alteration ofdrainages. However, these speciesappear to respond well toreasonable land managementpractices.
to page 11
11 Forest Practices News vol 3 no 2
Flora
of reservation, improvedland use techniques andm a n a g e m e n tagreements withlandholders andforestry, agriculturaland urban or publicstakeholders;• Increase publicawareness of thesespecies andinvolvement in orwillingness to beinvolved in
conservation related programs;and
• Monitor each species ats e l e c t e dmonitoring sitesto determine theeffects ofr e c o v e r yactions over thelong-term.
The protection andmanagement of thefour Engaeus specieswill have directconservation andbiodiversity benefitsfor other stream-dwelling andstream-associated
Figure 1: Engaeus sp. showing the typical size ofburrowing crayfish.
Figure 2: Engaeus yabbimunna - the Burnie burrowingcrayfish
A five-year Recovery Plan(Burrowing Crayfish Group RecoveryPlan 2001-2005) has been producedto address these threats. A draftversion of the plan was recentlyavailable for public comment andwill now be adopted by DPIWE.Copies of the final plan will beavailable soon, and funding isbeing sought for itsimplementation. The objective ofthe Plan is to stabilise and improvethe conservation status of thesespecies for potential down listingin future.
To meet this objective, the Plan aimsto:• Improve the security for each
species through a combination
species (including other listedspecies) within these areas. It willalso directly benefit water qualityand waterway health in the Burnieand Dorset communities.Management actions andprescriptions for forestry operationshave already been developed in co-operation with the Forest PracticesBoard and individual forestrycompanies, and can be readilytailored to specific sites.
For more information contact theSenior Zoologist, FPB.
Tasmanian orchids – not just a pretty faceMark Wapstra, Scientific Officer, Forest Practices Board
Fred Duncan, Senior Botanist, Forest Practices Board
Our daily work in managing production forests involves a strong focus on “special” values such as threatenedflora and fauna. Sometimes it is useful to take a step back to consider some of the more common features ofthe forest and the role they play in its functioning. In this article, we examine the orchids - a fascinating anddiverse group of plants that are often overlooked. They provide many good examples of the interactions thatoccur within our native forests and other ecosystems.
Orchids are monocotyledons (i.e.they are grouped with the grasses,sedges and lilies). While Tasmanialacks the familiar cultivatedorchids and the spectaculartropical species, its orchid flora isquite diverse. Orchids occupyalmost every habitat from the coastto the highest peaks. Only two ofTasmanian species grow on treesor rocks – the rest are terrestrial.
Recent work by Jones et al. (1999)has shown that Tasmania is hometo over 190 species. This comprisesabout 12% of Tasmania’s vascularflora.
Most Tasmanian orchid species areeasy to overlook in their vegetativestate. In fact, because many areephemeral, they are often notobvious at all – occurring as bulbs
or tubers below the ground, withnot even a leaf giving a clue towhat may emerge when seasonaland site conditions are favourable.However, even the smallestspecies are spectacular orintriguing when they flower.Orchids are characterised by adistinctive flower structure inwhich one of the petals is oftenhighly modified to form the
12Forest Practices News vol 3 no 2
Flora“labellum” (see line drawing). Thisstructure is often enlarged,brightly coloured or ornamentedwith shiny glands, teeth, or calli –all with the principal aim ofattracting insects for the purposeof pollination. Orchids use a widevariety of techniques for ensuringpollination – attracting pollinatorsby colour, fragrance, nectarrewards, mimicry of other flowersand the release of scents. Wedescribe just a few of thesetechniques below, hopefullygiving an insight into the complexworld of these diminutive plants.
The beard orchids (genusCalochilus) and the bird orchids(genus Chiloglottis)Beard orchids get their name fromtheir large hairy labellum (seephoto). Species of beard orchidare pollinated by male scollidwasps. Flowers release a scent thatmimics the pheromones of thefemale wasp. They also possess apair of glossy eye-like glands atthe base of the labellum, which isthought to resemble the shape ofthe female wasp. The combinationof the visual and the olfactory cueslures the unsuspecting male waspswhich, in attempting to mate withthe labellum, pollinate the flower.However, if subterfuge or scentdon’t work, beard orchids can alsoself-pollinate.
Calochilus robertsonii (purple beardorchid) Note the very hairy labellumand the glands at the base of thelabellum. Photo: H & A Wapstra
Bird orchids are common in wetand dry forests and there areseveral species in Tasmania, withcolonies of different species oftengrowing side by side. The flowersof Chiloglottis are pollinated bymale thynnine wasps that attemptto mate with the labellum afterbeing attracted by the release of ascent (and by the appearance ofthe labellum –it possesses shinyraised calli). But the story is morecomplex than it first appears.Recently, several “new” specieswere recognised within theChiloglottis gunnii complex (at leastthree distinct species). Differentspecies of wasp are “faithful” to aparticular Chiloglottis species soclosely related species can growright next to each other withouthybridising.
Chiloglottis triceratops (three-hornedbird orchid) and Chiloglottis
grammata (small bird orchid). Notethe overall similarity in shape of
flower but different arrangement ofcalli on the labellum. Photo: H & A
Wapstra
The greenhoods (genusPterostylis) and the duck orchids(genus Caleana)Greenhoods are a diverse genusand one of the more familiar of theforest orchids (see photo). Theyhave a great diversity inappearance but all possess alabellum that is actively motile.The labellum is held in place by aturgid strap which, when touchedby an insect, flips the labelluminwards towards the reproductiveorgans of the plant. This traps the
insect inside the “cell” made bythe flipped labellum and theadjacent part of the flower. Thescramblings of the trapped insectresult in it picking up (ordepositing) pollen, as it is guidedover the exposed stigma byspecialised floral structures. Thelabellum eventually returns to theset position allowing other insectsto be caught. The spectacular duckorchids (Caleana major and Caleanaminor) also achieve pollination ina similar manner (see photo).
Pterostylis melagramma (black-stripegreenhood). Photo: M. Wapstra
Caleana major (flying duck orchid) Notethe head of the “duck” on the strap –this head flips down into the duck’s“body” when an insect touches theflower, trapping the insect inside the
flower. Photo: H & A Wapstra
13 Forest Practices News vol 3 no 2
Soils
These examples of interactionsbetween orchids and animalspecies suggest that orchids canbe good indicators of the ecological“health” of an area. Many orchidspecies are very susceptible tochanges in site conditions. Forexample, addition of fertilisers canlead to loss of orchid species frombushland because of competitionfrom introduced species andbecause mycorrhizal fungi on theirroots take up phosphorus andconcentrate it to toxic levels.Changes in fire regimes can alsoaffect orchids. Flowering of someorchid species (e.g. Thelymitracyanea) is stimulated by fire. Manyspecies are favoured by infrequenthot fires (which temporarilyremove competing or shadingspecies). Frequent cool burns(especially in spring when mostorchids are actively growing) candeplete orchid populations in anarea. .The conservation status of manyTasmanian orchid species is poorlyknown, partly because of theephemeral nature of most species.The review by Jones et al. (1999)suggests that 30 species areendangered and many more areotherwise threatened. There arerelatively few threatened species
(less than 10) in forest types mostfavoured for production of sawlogor pulpwood, but numbersincrease as timber quality goesdown. Most threatened species arefound in vegetation types such asnative grassland, heath, wetlandand woodlands, which are oftenlocalised and have also beensubstantially modified byagriculture and settlement.Maintenance of threatened orchidspecies, and orchid diversity, mayneed to be considered by forestplanners if forest-related activities(e.g. roading, fuel reductionburning) will affect theseenvironments.
Hopefully, this article willencourage forest workers to lookclosely at this intriguing plantfamily. A handlens will help youappreciate the intricate pattens andshapes of the orchid flowers. Youmay even get the chance to releasea trapped insect from its pollen-filled prison. The Orchids ofTasmania (Jones et al. 1999) is thebest source of information onidentification and distribution, butat $80 a copy it is probably bestused in the office or at home. ThePlant Identikit to Orchids of Tasmaniaproduced by Society for Growing
Australian Plants (price about $9from Forestry Tasmania andbookshops) is a good option forallowing you to identify thedifferent genera and some of themore common species.Specimens can also be sent to theForest Practices Board foridentification. However, nevercollect specimens from StateReserves without a permit, or fromcolonies containing only a fewindividuals. A couple of flowersare usually sufficient, rather thanthe whole plant. It is easiest toidentify fresh material – send itbetween a few sheets of moist (notsoggy) tissue paper, placed in aplastic bag.
This article has borrowed heavilyfrom The Orchids of Tasmania by D.Jones, H. Wapstra, P. Tonelli andS. Harris, published by MelbourneUniversity Press (1999). Withexcellent colour plates, specieskeys and descriptions anddistribution maps, along withinformation on orchid ecology andconservation, it will be useful toanyone interested in Tasmania’sorchids and its flora in general.
A rough field guide for assessing soil erodibilityMike Laffan, Senior Soil Scientist, Forestry Tasmania
IntroductionThe erodibility status ofTasmanian forest soils is animportant component of the ForestPractices Code (ForestryCommission Tasmania 1993).Erodibility largely determineshow soils should be managed,particularly during operations thatdisturb the soil surface such asthinning, harvesting, roadconstruction and site preparationprior to planting. The Forestpractices Code stipulates variouscontrol measures designed toprevent erosion during forestry
operations according to theclassification of soil erodibility.There are 5 classes of erodibilityincluding Low, Moderate,Moderate-High, High, and VeryHigh. Clearly, highly and veryhighly erodible soils require morestringent managementprescriptions than soils with lowerodibility.
Erodibility is defined as theinherent susceptibility of soil tothe detachment and transport ofsoil particles or aggregates byerosive agents such as rainfall,
runoff, through-flow, frost orwind. In the Forest Practices Codeerodibility is concerned mainlywith susceptibility to erosion byrainfall and runoff, but erosion bywind is important on sites such assand dunes. Erodibility isdetermined by various propertiesthat resist detachment andtransport of soil, and the rate atwhich rainfall and runoff can enterand percolate the soil. A semi-quantitative methodology wasdeveloped (Laffan et al. 1996) forassessing the erodibility class ofTasmanian forest soils based on
Soilsboth field and laboratorydeterminations of soil properties.They include the proportion ofwater-stable aggregates using wet-sieving and/or dispersion tests,soil strength, stone content,thickness of soil layers, andpermeability and drainage classes.
Generally, deep sandy soils or soilswith sandy or silty layers occurringbetween loamy and/or clayeylayers are highly erodible, whereaswell drained loamy or clayey soilshave low or moderate erodibility.However, deep loamy and clayeysoils with slow permeability and/or impeded drainage (usuallypoorly-structured clays or soilssubject to high water-tables) aregenerally readily saturatedfollowing rainfall and are likely togenerate more runoff and thuscause greater erosion than soilswith moderate or highpermeability. Consequently, soilswith impeded drainage (normallycharacterised by grey andyellowish-brown mottling ordominantly greyish-colours insubsoils) usually have a moderate-high rating of erodibility.Erodibility is also dependent onthe stone content (coarsefragments > 20mm) of soils and onthe presence of hard pans. Surfacestones and hard pans protect soilaggregates and particles fromraindrop splash and detachment,and also slow runoff andtransportation of detachedmaterials. Very stony soils andsoils with massive hard pans areless erodible than similar soils withnil or only few stones and withouthard pans.
The method of Laffan et al. (1996)has been used to determine theerodibility rating of a wide rangeof forest soils from throughoutTasmania (Grant et al. 1995a) andfor a large number of soils mappedat 1: 50 000 scale in northernTasmania (Grant et al. 1995b,Laffan et al. 1995, and Hill et al.
1995). Recently, this informationhas been summarised on the basisof geology, soil profile features,soil drainage class and nativevegetation type for use in a rapidfield procedure for assessingplantation potential (Laffan, inpress). However, not allTasmanian forest soils have beencharacterised and tested for theirerodibility rating, and often it isdifficult to correlate soils found inthe field with those alreadydescribed in the abovepublications. To overcome theselimitations and to facilitate theassignment of a soil erodibilityclass during the preparation ofForest Practices Plans thefollowing field guide provides anapproximate assessment for ratingerodibility.
Assessing soil erodibility fromsoil texture, colour, stoniness,strength (hard pans) and nativevegetation type
Step 1 – expose soil profile
The first step is to expose the soilprofile to a depth of at least 80cm(unless prevented by stones orhard pans), either by digging witha hand auger or spade, or bycleaning up an existing profileformed by a road or track batter,ditch, etc. If using an existingprofile, ensure that it representsthe natural soil profile and hasn’tbeen disturbed by removal ofupper layers or had materialdumped on top.
The area being assessed should bestratified according to geology,landform and native vegetationtype and at least 2 soil observationsmade in each stratum.
Step 2 determine texture of eachsoil layer and overall stoninessof soil profile
The second step is to determinethe texture of each soil layer and to
classify the profile into one of thefollowing soil textural groups:
1) Profile is loamy and/or clayeythroughout (no bleachedsandy or silty layer >10cmthick is present),
2) Profile has a bleached (white,light grey, pale yellow or palebrown) sandy (includingsandy loam) or silty (includingsilt loam) subsurface layer (>10cm thick) overlying loamyor clayey subsoils,
3) Profile is sandy throughout.
For soils where a bleached sandyor silty layer less than 10cm thickoccurs, then classify the profile asloamy or clayey throughout.
Texture should be determinedusing a moist sample of soil ofsufficient size to fit comfortablyinto the palm of the hand. Broadtextural classes are defined asfollow s: Sandy soils feel very grittyand have nil or only weakcoherence when a moist sample issqueezed in the palm of the hand.Loamy soils are coherent whensqueezed and they include a widerange of different particle sizes;sandy loams feel very sandy, siltloams have a smooth or ‘silky’feel, and clay loams aremoderately plastic and form aribbon of 40-50mm when pressedout between thumb and forefinger.Clayey soils are strongly plasticand will form a ribbon >50mmlong when pressed between thumband forefinger. Silty soils aredominated by silt-sized particlesand feel very smooth and silkyand usually dry out on the hand toform pale-coloured fine-powderydeposits. For the purposes of thisguide, sandy soils include sandsand sandy loams, and silty soilsinclude silts and silt loams.
In sites where stony soils areencountered, stone content (%) ofthe whole soil profile must beassessed from a vertical exposure
15 Forest Practices News vol 3 no 2
Soils(pit, road batter, ditch). Estimate visually whether stoniness is < 50% or > 50%.
Step 3 key out soil erodibility rating using soil texture and colour, (and stone content and presence of hardpans where appropriate) and native vegetation type
In the third step the erodibility of the soil is keyed out based mainly on colour and texture of topsoils andsubsoils, and on type of native vegetation.
Table 1 : Key for assessing the erodibility rating of Tasmanian forest soils based on soil texture andcolour and native vegetation type
Profile texture and colour and native vegetation type Erodibility Rating 1,2
1) Profile is loamy and/or clayey throughout (no sandy or silty layer present)
- Dark-coloured loamy topsoils overlie yellow or brown or red clayey subsoils under wet forest .......L- Dark-coloured loamy topsoils overlie yellow or brown or red clayey subsoils under dry forest ........M3
- Dark-coloured sandy loam topsoils overlie yellow or brown or dark-coloured loamy orclayey subsoils under wet forest ................................................................................................................................M
- Dark-coloured loamy topsoils overlie grey and yellow (or brown) mottled clayey subsoils(or subsoils are dominantly grey/ or blue clays) under scrub or swamp forest or wet forest ..............MH
- Dark-coloured peaty topsoils overlie grey or brown loams or sands underscrub/sedgeland-heathland .........................................................................................................................................MH
2) Profile has bleached sandy or silty subsurface layer overlying loamy or clayey subsoils
- Dark-coloured topsoils overlie bleached sandy or silty subsurface layers which in turnoverlie loamy or clayey subsoils under wet or dry forest ..................................................................................H4
3) Profile is sandy throughout
- Dark or pale-coloured coarse sandy topsoils overlie bleached or pale-coloured coarsesandy alluvial deposits (from granite) under dry forest ....................................................................................VH
- Dark-coloured topsoils overlie bleached or pale-coloured sands under wet or dry forest ....................H
- Dark-coloured sandy topsoils overlie yellow or brown sands(with or without bleached sandy layers) on aeolian dunes under dry scrub ..............................................H5
- Pale-coloured very recent aeolian sands under dry scrub or grassland, or actively- eroding yellow or brown aeolian sands ...................................................................................................................VH5
1Refers to erodibility by rainfall and runoff apart from soils on aeolian sands (footnote 5).Key to codes; L = Low, M = Moderate, MH = Moderate-high, H = High, VH = Very High
2Decrease rating by 1 class (e.g. from H to MH, from MH to M, etc) for very stony soils (>50% stones), andsoils where bleached sandy/silty layers are massive and hard.
3Rating is L for soils on basalt under dry forest
4Rating is VH for soils characterised by pale-coloured coarse sandy topsoils overlying thick (>50cm)bleached coarse sandy layers which in turn overlie yellow or brown clays. They occur only on granitesunder dry forest in north-east Tasmania.
5Erodibility by wind.
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SoilsDry forest includes dry eucalyptforest and open eucalyptwoodland, whereas wet forestincludes damp eucalypt forest, weteucalypt forest, mixed forest andrainforest. Scrub includes densescrubby vegetation about 2-5m inheight, and sedgeland/heathlandcovers low vegetation commonlycontaining buttongrass. Swampforest includes very wet sitesdominated by blackwood oreucalpts such as E ovata. Type ofsubstrate (geology) is required forloamy or clayey soils under dryforest so as to differentiate soils onbasalt which have low erodibilitycompared to moderately erodiblesoils on other substrates.
For some sandy soils the thicknessof bleached layers and type ofsubstrate (granite) is also required.Very highly erodible soils areessentially confined to coarse-sandy soils on granite under dryforest in north-east Tasmania inareas where high intensity rainfallsoccur periodically. These soils aremainly found on deep alluvialdeposits of coarse sand in gulliesand lower slope positions, butsome also occur on hillslopeswhere they are characterised bypale-coloured coarse sandytopsoils overlying thick (> 50cm)bleached coarse sands which inturn overlie yellow or brownclayey subsoils.
In the key, soils with bleachedsandy layers occurring betweendark-coloured topsoils and loamyor clayey subsoils are rated ashaving high erodibility. It shouldbe noted that some of these soilshave previously been rated ashaving moderate-high erodibility(Grant et al. 1995b, Laffan et al.1995, and Hill et al. 1995) based onthe occurrence of well-structuredloamy or clayey subsoils withmoderate permeability rather thanthe normal situation of poorly-structured loams or clays withslow permeability. However,recent field evidence of severesurface erosion following heavyrainfall in a soil with bleachedsandy layers overlying well-structured loamy subsoilsindicates that these soils wouldprobably be more appropriatelyclassified as having higherodibility.
Very stony soils (> 50% stones) aredecreased by 1 erodibility class,e.g. very stony soils with bleachedsandy or silty layers are decreasedfrom high to moderate-high. Soilswith > 90% stones are rated as lowerodibility, regardless of texture.Likewise, soils where the bleachedsandy or silty layers are massiveand hard, are decreased by 1erodibility class. Note that wherea relatively soft, bleached sandy
or silty layer overlies a bleachedhard pan, then the erodibility isstill assessed as high.
Grant, J.C., Laffan, M.D., Hill, R.B.and Neilsen, W.A. 1995a ForestSoils of Tasmania. A Handbook forIdentification and Management.Forestry Tasmania.
Grant, J.C., Laffan, M.D. and Hill,R.B. 1995b Soils of Tasmanian StateForests. 2. Forester Sheet, North-East Tasmania. ForestryTasmania.
Hill, R.B., Laffan, M.D. and Grant,J.C. 1995 Soils of Tasmanian StateForests. 3. Forth Sheet, North-WestTasmania. Forestry Tasmania.
Laffan, M.D., Grant, J.C. and Hill,R.B. 1995 Soils of Tasmanian StateForests. 1. Pipers Sheet, North-EastTasmania. Forestry Tasmania.
Laffan, M., Grant, J. and Hill, R.1996 A method for assessing theerodibility of Tasmanian forestsoils. Australian Journal of Soil andWater Conservation 9: 16-22.
Laffan, M. (In Press) A rapid fieldmethod for assessing sitesuitability for plantations inTasmania. Tasforests.
§ Mike Laffan§ Fred Duncan§ Brooke Craven§ Robbie Gaffney§ Niall Doran§ Esme Atkinson§ Mark Wapstra§ Sarah Munks§ Peter McIntosh§ Chris Mitchell§ Graham Wilkinson§ Kevin Kiernan
17 Forest Practices News vol 3 no 2
GeomorphologyGroundwater conditions in basalt landscapes – some speculation
Kevin Kiernan, Senior Geomorphologist, Forest Practices Board
Ever wondered about the large springs that are a feature of some Tasmanian basalt areas? So have I. Theconventional explanation is that rainfall steeps down joints in the rock until it reaches an obstruction thatforces it to flow laterally to the spring. The obstruction may be either an impermeable rock type at the baseof the basalt, or perhaps an earlier basalt lava flow on which clayey soil or sediment accumulated prior to latereruption of the upper lava flow.
But even well jointed columnarbasalt may perch much more waterthan it allows to infiltrateunderground (Figure 1). It isdifficult to envisage theconsiderable discharge from somesprings in basalt as flowing justthrough relatively minor spaceslike joints, and although weatheringand erosion is likely to permit someenlargement of trunk conduitsover time, basalt is not as prone tothis as limestone in which largecave systems may develop. Inaddition, some springs in basaltrespond very rapidly to rainfallevents. Whereas a subduedresponse might be expected wherejointed rocks act like a sponge thatslowly releases water, some ofthose springs behave more like anurban stormwater drain system ofopen pipes. Why might that be soand what might be theimplications?
Figure 1: Waterfall over columnarbasalt – although the rock is well
jointed surface water flows across itrather than sinking rapidly
underground.
Open Spaces in basaltThe mode of formation ofTasmania’s basalt lava flows hasreceived little study, but it hasimplications for potential water-carrying spaces in basalt. In thepast, large lava flows havegenerally been considered to haveformed simply by a flood surge ofmolten rock. The difficulty withthis is that where the gradient ofthe slope is low lava flows slowlyand its surface quickly cools andcongeals, like porridge spilt acrossa breakfast tray. In recent decadesthere has been increasingrecognition that a process know astube-fed flow can sometimes beimportant. The cooled upper“skin” of the lava “porridge”insulates the hotter lava beneath.If lava continues to flow from thevent, it slips in under the cool skin,inflating the lava flow a bit like atyre being pumped up. Theflowing subsurface lava organisesitself into tubes, and by this meansnew hot lava is conducted towardsthe front of the lava flow, allowingit to advance. As the eruptionsubsides the lava in the tubes alsocools and congeals, blocking them.But in some cases the hot lavadrains out of tubes leaving themempty. Work done some yearsago on some of our youngest lavaflows near Great Lake bySutherland confirmed thepresence of undrained lava tubesthere. But our older lavas are oftendeeply buried beneath youngersediment or soil, and are wellweathered, so their originalstructure and structure at depth isdifficult to discern. But mightwater moving through lava tubes
explain the characteristic of someTasmanian springs in basalt?
Leaky LakiIn September 2000 I joined anexpedition organised by a Britishuniversity to examine a very recentand fresh lava flow. My personalagenda was to assess the extent towhich lava tubes might act asunderground watercourses. The1783 - 84 Laki lava flow in southernIceland is the largest lava flow tohave occurred on Earth in recordedhuman history. According to astudy by Thordarson and Self(1993) the eruption was precededin May – June 1783 by earthquakesso strong that people 40 – 50 kmdistant chose to sleep outside intents. The in June the eruptioncommenced, along a 27 km ventsystem. It produced over 14million km3 of lava in just 10months. At its peak, fire fountainsreached 800 – 1400 m high andconvecting eruption columnsreached 15km altitude. There was nodirect loss of life from the lava. Butthe effects were devastatingnonetheless – grass growth wasstunted, 50% of Iceland’s livestockdied from fluorine poisoning, andcatches from fresh to saltwaterfisheries declined. The subsequent“haze famine” coupled withensuing severe winters andvarious diseases killed 10,521Icelanders (22% of the population),Solar radiation was affected bythe ash thrown into theatmosphere, which has beensuggested to have loweredtemperatures 1 – 2 º in the northernhemisphere in 1783 – 85. Fieldsturned black on the Faeroe Islands,
18Forest Practices News vol 3 no 2
Geormorphologyand crops were spoiled in Scotlandin 1783 “the year of the ashie”.Ashfall affected grasslands inWestern Europe with haze or dryfog over Europe, northern Africa,and western Asia and dry fogs inNorth America.
Lava flow from this eruption wasvery rapid, the Skafta Gorge, 0 – 5km wide and 200 m deep, wasfilled in 4 – 5 days; the westernarm of the Laki flow travelled 35km in only 4 days. The Laki flowhas sometimes been quoted asbeing a great example of a “floodbasalt”. The Classical ColumbiaRiver flood Basalt Group dischargewas 2 – 3 orders of magnitudelarger, but that occurred over 5years – discharge rates at Lakiappear to have been comparable.But the Laki flow is not a floodbasalt – it exhibits abundantevidence of actually having beentube fed. Shallow lava tubes arewidely exposed, collapse pits intotubes are common, and there areextensive canyons formed bycollapse of tube rooves.
Because the Laki flow is veryrecent, the sediments and soil thatobscure the view in Tasmania arenot an issue. We soon found majorsprings including one with adischarge far exceeding that of anykarst spring in Tasmania (Figure2).Further up the lava flow we alsofound major streamsinks intocollapse pits (Figure 3). Periodicheavy rain also allowed us towitness rapid fluctuations inspring discharge like wesometimes see in Tasmania. Mostof the drained lava tubes whichcould be entered were small andshort, at fairly shallow depth in thebasalt (Figure 4); they are easilypenetrated by water from thesurface. We also gained access tomore extensive systems, includingsome through which majorstreams flowed (Figure 5) andothers that were coated with silts
Figure 2: Large spring in the Laki lava flow – note the human figures for scale
Figure 3: Large streamsink into a collapse pit in the Laki lava flow
indicative of their being totally filled by floodwaters at times. In just onelittle corner of the Laki flow our party surveyed about 3 km of braidedtube system, without having time to complete the task. Elsewhere inIceland we examined open lava tubes of massive size (Figures 6 and 7).
Figure 4: Entrance to a lava tube on the Laki flow, showing large sizeand shallow depth below the surface.
19 Forest Practices News vol 3 no 2
Geormorphology
Figure 5: Water pouring through the roof of a lava tube into a major subsurfacestream passage.
Figure 6: Cone of windblown snow in the entrance to another Icelandic lava tube.Some of the tubes are floored by ice rather then flowing liquid.
Figure 7: Large, open lava tubes have the potential to allow subsurface streamscomparable to those that occur in karst caves – and just as easily polluted.
Possible implicationsOur investigations on the Laki flowconfirmed that it involvedtube-fed flow, and that drainedlava tubes act as major pathwaysfor subsurface water flow. In someareas where glaciers extend ontothe lava flow, sediment hascovered the lava and smallsediment cones have formedunderground in some tubes.Moisture is still able to move downthrough small fractures into tubesthat remain unclogged bysediment. Once the fracturesleading from the surface are partlyclogged, sediment movement intothe tubes seems to decline,although water can still seep intothem to nourish undergroundstreams.
The evidence from the Laki flowsuggest water flow through lavatubes is a reasonable hypothesis toaccount for some Tasmaniansprings in basalt. While this remainsa hypothesis and not a proven factit suggests some caution isrequired. Lava tubes are big openpipes that allow speedytransmission of any pollutant withno potential for significant“natural purification” – littledifferent to the karst situation.Moreover, given that lava tubesmaintain a low gradient at shallowdepth beneath a lava surface, theirefficiency in collecting andtransmitting polluted water mightbe quite comparable to karst caves.While the thicker soils andsediment covers in Tasmania offera degree of potential buffering,how effective that may be remainsto be tested. Until further researchallows some more precisesanswers, we can add uncertaintiesregarding groundwater to theoccasional landslide issues thatneed to be borne in mind inmanaging forestry in Tasmanianbasalt landscapes.
