This publication is copyright. Apart from any fair dealing for private study, research, criticism or review as permitted under the Copyright Act 1968, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, photocopying or otherwise, without prior permission of the copyright owner.

National Library of Australia
Cataloguing-In-Publication entry:
Victoria. Dept. of Natural Resources and Environment

Burgman, Mark A.
Rainforest in Victoria: a review of the scientific basis of current and proposed protection measures
Management Area.

Bibliography.
ISSN 1324-7778
ISBN 0 7306 6111 3
1. Rain forests - Victoria - Management.
2. Logging - Environmental aspects - Victoria.
I.Ferguson, I.S. (Ian S.). II. Victoria. Dept. of Conservation and Natural Resources. III. Victoria. Forests Service. IV. Title.
(Series: Forests service technical reports; 95-4).
333.751609945

Preface

The attached report was commissioned by the Department of Conservation and Natural Resources in August 1993.

It was commissioned to help resolve scientific questions relating to the management and protection of rainforest stands in areas where timber harvesting is a permitted land-use. It is based on extensive research and consultation with relevant experts by its authors, Dr Mark Burgman and Professor Ian Ferguson from the University of Melbourne.

Unlike other parts of Australia where rainforests are found, Victorian rainforests tend to occur as discrete stands, making it difficult to ensure their protection by formal reservation alone. The dynamic equilibrium between rainforests and surrounding eucalypt forests is also continuously changing as a result of natural processes, making the development of strategies which permit such processes to continue unhindered while providing for other important community uses such as timber production a considerable challenge.

The consultants have done a thorough job of summarising current scientific and related information, and of evaluating the complex issues associated with various protective strategies for rainforest. The review findings have been forwarded to the CSIRO's Division of Forestry which is currently conducting a review of Victoria's Code of Forest Practices for Timber Production. The findings are also under detailed consideration by CNR staff engaged in the preparation of Forest Management Plans.

Richard Rawson
Director, Forests Service

Summary

The Basis for Judgements

Ecological processes in rainforest, including regeneration from fire and competitive interactions with adjacent sclerophyll communities, operate on time scales of hundreds of years, making the observation of changes and the inference of impact difficult. These considerations are compounded by the fact that many of these processes interact with each other, with the shape and area of rainforest stands, and with other biotic and abiotic components of the ecosystem. In the absence of relevant information from Victorian ecosystems, the best that can be done is to infer the potential for impacts from the above processes, from studies undertaken elsewhere. This approach suffers from the uncertainty that responses in Victorian ecosystems may not be analogous to responses observed in forests in other environments. The unusual composition and ecological dynamics, particularly the disturbance dynamics, of Victorian communities provides grounds for supposing that responses to disturbance may be unique. Thus, while we may expect similar qualitative responses to disturbance to those observed elsewhere, the quantitative response is uncertain.

Potential Impacts on Rainforest

Despite such difficulties, judgements on the potential for impact of forest management on rainforest values must be made. Conservation of Victorian rainforest involves issues of both species and ecosystem conservation. The processes at work in Victorian forests that may affect the conservation status of rainforest communities have been identified from field observations, and from inferences made from analogous ecological systems elsewhere, where such comparisons are appropriate. They include changes in natural fire regimes, the potential for increased disease incidence (including Phytophthora cinnamomi and myrtle wilt), the potential for ecotone disturbance from site preparation burns, edge effects on ecotones and mature rainforest from windthrow, changes in microclimate, weed invasion and other floristic and faunal changes.

There is a prima facie case that current management practices in timber utilisation areas have the potential to elevate the risks of impact on some rainforest values in the medium or long term, especially in those stands protected only by the Code of Forest Practices for timber production. If there is a significant adverse impact, the consequence for stands protected only by the Code of Forest Practices is that the interval between events may not be sufficiently long to ensure recovery of the rainforest-sclerophyll forest ecotone from the incursion of edge effects. Nor may it be long enough to ensure full recovery of mature rainforest after other disturbances such as disease with which adjacent timber harvesting activities may interact. Rainforest protection measures must also consider the possibility that some impacts such as weed invasion and disease represent change from which there may be no recovery.

Planning Procedures

CNR relies on three integrated management planning strategies, namely the LCC landuse review process, the Forest Management Area planning process, and compliance with the Code of Forest Practice. There are additional requirement for management of cool temperaterainforest and for the management of individual rainforest species under the Flora and Fauna Guarantee Act. Current planning processes such as those applied in the draft East Gippsland Forest Management Area plan are an effective mechanism for allocating conservation priorities and should be applied in the development of other Forest Management Area plans. Some additional planning processes are recommended.

The LCC, in its final recommendations for East Gippsland, indicated it would be carrying out an investigation of rainforests in Victoria with a view to making recommendations on the range of uses for rainforest and the way in which rainforest in Victoria could be protected through reservation. This review has not been carried out. However, information from the National Rainforest Conservation Program is available to planners, placing a special responsibility on them to take this fact into account. Furthermore, only one Forest Management Area plan has been completed. Recommendations have been made regarding interim measures for rainforest protection until Forest Management Area plans are complete so that planning options are not pre-empted. It is also recommended that protection measures in Forest Management Area plans should take account of the characteristics and importance of the conservation values of a stand, the likely proximity and intensity of the proposed impact, site topography and disturbance history.

It is suggested that mixed forest be separately classified from other forest types and that management procedures be implemented to ensure the preservation of all forest values within it. More generally, all forest management practices that affect rainforest and associated ecosystems, particularly harvesting and regeneration practices, should aim to maintain or restore pre-disturbance species composition at all sites.

The resolution of differences of scientific opinion and the implementation of management strategies that ensure adequate protection may only be made by the acquisition of empirical data. Until such data are acquired, it is incumbent on planners to treat rainforest threats cautiously, and to implement protection measures that will cope with the potential for long-term and landscape scale impacts. Given that the Government accepts the principle that forest management must provide for the ecological sustainability of all rainforest values, rainforest must be afforded the benefit of the doubt in areas where the values are nationally significant or irreplaceable, and where there is uncertainty about the impacts that may result from management.

The data most urgently required for planning adequate protection for rainforest include estimates of the background probability of disease and fire events, together with the risks of impact due to timber harvesting activities. There will necessarily be a delay before these data are available. Management recommendations are made to mitigate the potential for adverse impacts of management on rainforest. Research recommendations aim to provide the information that is most important for future management decisions as quickly and efficiently as possible. In addition to the results of monitoring studies, useful results are attainable within about three years. Collaboration is strongly recommended with interested research institutions including universities, the CSIRO, and the research divisions of private companies.

Recommendations

The following specific recommendations for protection management and scientific research are made in the body of the text.

Delineation

Continue the delineation, description and rating of proposed Sites of Significance for rainforest by the Flora Section, ensuring full documentation of values and reasoning so that the process is transparent, thereby facilitating its use in forest planning and making it available for public scrutiny. (p. 53)

Continue to improve the determination of the boundaries of rainforest in the field through the implementation of keys based on the presence and absence of differential species. (p. 53)

Enable and encourage Departmental field officers to establish buffers greater than the prescribed minimum, where the need for protection of rainforest in special circumstances such as unusual exposure conditions can be justified. (p. 55)

Complete the process currently underway of delineation of core areas within proposed Sites of Significance. This delineation should be based on close collaboration between Forest Management Area forest planners and staff from Flora Branch. The core areas should be clearly marked on maps and the associated values for each rainforest site should be listed. (p. 63)

Protection

Continue procedures involving four levels of protection for rainforest used by CNR, namely conservation reserves, Special Protection Zones, Special Management Zones, and the Code of Forest Practice, as a means of allocating priorities. (p. 56)

Continue to incorporate the most significant rainforest sites in State Forest within Special Protection Zones, or provide sub-catchment protection. (p. 56)

Continue to conduct allocation of priorities and landscape protection measures for rainforest through forest planners in close collaboration with CNR staff with appropriate expertise in flora and fauna. (p. 56)

Note in Forest Management Area plans a summary of and Departmental file sources for the advice on rainforest protection received by planners. Provide details of compromises in terms of costs to all forest values. (p. 56)

Design protection measures to take into account the conservation importance of rainforest stands, and the severity and proximity of proposed impacts. As part of this process, Departmental policy should recognise the need for delineation of core areas, and the ranking of Sites of Significance. Core areas should be the focus of management planning because they represent judgements for the management of risks faced by rainforest, taking into account site topography, proposed management operations, disturbance history and the susceptibility of rainforest values to operations. Generally, core areas in proposed Sites of Regional and State Significance should have protection levels intermediate between the protection afforded to proposed Sites of National Significance and the least significant rainforest stands. (p. 62)

Develop plans for rainforest protection in each Forest Management Area such that the most important rainforest areas are afforded highest protection. Buffers should be either minimum of 40m complete exclusion of disturbance or 20m complete exclusion plus 40m modified harvesting (see below) for sites of least significance. Where Nothofagus makes up greater than 20% of the canopy, the minimum buffer for the least significant stands should be extended to either 60m or 40m complete exclusion plus 40m of modified harvesting. Subcatchment protection should be afforded to stands that harbour nationally significant rainforest values that are sensitive to management operations, unless it can be demonstrated that such protection is unnecessary. (p. 63)

Publish all maps of core areas and details of their rainforest values, together with rationalisations of protection prescriptions, in Forest Management Area plans where they may be subjected to public scrutiny. (p. 63)

Continue to recognise as rainforest, vegetation currently classified as rainforest, irrespective of losses to fire. (p. 63)

Implement specific procedures for supervision of compliance and independent monitoring of rainforest protection measures in all FMAs. (p. 63)

Consider the implementation of a 40m wide modified harvesting zone which, so far as practicable, reduces machine disturbance and burning to a minimum, and retains at least 40% of the standing basal area with feathering of edges closest to the buffer. (p. 63-64)

Planning

Implement interim protection plans for all proposed Sites of Significance for rainforest, including National, State and Regional Sites, to ensure that operations do not pre-empt planning outcomes. (p. 57)

Consider all interim measures for rainforest protection for adoption in the completed Forest Management Area plan. (p. 57)

Ensure that planning for rainforest protection addresses both landscape and site-specific management perspectives. Identify biogeographic areas with FMAs, and develop protection strategies at a landscape scale before proceeding to evaluate protection measures for individual stands and sub-catchments. Make reference to the National Rainforest Conservation Program in planning procedures. (p. 58)

Use proposed Sites of Significance as a basis for planning landscape level protection prescriptions. (p. 58)

Revise sustainable yield estimates at the next revision of the Forest Management Area plan. The Department should anticipate changes to sustainable yield contingent on areas being removed from harvesting, as soon as this information becomes available. (p.59)

Recognise 'mixed forests' as a separate community and develop specific management prescriptions for this forest type that ensure the preservation and sustainability of all forest values. (p. 59)

Ensure that monitoring procedures are statistically valid and adequate to the task of the evaluation of all potential impacts on rainforest that result from management practices. Implement long term monitoring programs that have sufficient power to detect important ecological changes in rainforest stands. (p. 60)

Harvesting and Roading

Implement disease prevention strategies and strict hygiene measures while roading in or near cool temperate rainforest where Nothofagus cunninghamii contributes more than 20% to the vegetation canopy, to protect against the spread of myrtle wilt. (p. 62)

Minimise the amount of road construction activity, particularly in cool temperate rainforest stands. (p. 62)

Wherever practicable, minimise machine disturbance on fire breaks and boundary tracks. (p. 62)

Research
The research proposals below are listed approximately in order of importance.

Initiate a retrospective study of fire, topography, forest type and harvesting history in relation to rainforest stands. (p. 68)

Implement survey and monitoring programs for biotic and abiotic edge affects on rainforest. (p. 72)

Develop and implement a plan for inclusion of non-vascular cryptogrammic flora in monitoring of rainforest stands. (p. 72)

Undertake a retrospective study of the association between management history and disease status, and implement a monitoring program for Myrtle wilt. (p. 70)

Conduct a survey of cool temperate rainforest and mixed forest in Victoria with the aim of collecting data to establish current rates of myrtle wilt infection and the distribution of the disease among different forest types. (p. 69)

Implement a monitoring program to evaluate the rate of loss of trees of different size, shape, age, and species, as a function of the distance from an edge, topography, edaphic variables, and stand variables. (p. 69)

Evaluate the recovery dynamics and recovery times of rainforest and mixed forest following different types and intensities of disturbance. (p. 68)

Implement a study of the moisture regimes in myrtle wilt affected forests, with the aim of establishing their susceptibility to fire. (p. 70)

Initiate a research program into the spatial and temporal distribution of fire in Victorian forests. (p. 67)

Initiate a study aimed at determining the parameters and statistical properties of fire ignition and fire spread in forest types in which rainforest occurs. (p. 68)

Develop a stochastic model of myrtle wilt epidemiology, with the aims of improving understanding of disease dynamics, identifying those parameters to which the disease is most sensitive, and improving methods for hygiene. (p. 71)

printer friendly version