Defining, Identifying and Protecting Old-Growth Forest
​in Victoria 
by Trevor Poulton (2006)

http://www.forestnetwork.net/PDFs/old-growth-forest.pdf

Acknowledgments: Nicky Moffat, Tim Anderson, Tony Hastings, Lindsay Hesketh, Shelly Nundra​

​​​This book is primarily a literary review of the Victorian state government’s old-growth forest studies which were conducted by the government to map old-growth forest. The book is intended to assist members of the community seeking a basic understanding of the term ‘old-growth forest’ and how it has been identified by the state government in the field. The book is also intended to encourage the state government to develop appropriate and transparent methodologies for identifying and monitoring old-growth forest.  (Trevor Poulton 2006)  (96 pages including diagrams and tables)

1.      Introduction

Forests that have a highly mature tree structure with a complex understorey and possess conservation values such as hollows and fallen logs for wildlife habitat are commonly characterised as old-growth forest. Such forests often possess aesthetic qualities that inspire public empathy.
 
While logging practices are marketed by the Victorian state government as ecologically sustainable, logging of natural forests continues and is resulting in unsustainable loss of animal habitat and plant diversity and is diminishing an extraordinary and uniquely Australian environmental heritage. During the 1970s and 80s political focus of environment groups was on saving ‘wilderness’ and ‘natural forest’ (eg Routley 1974). The Department and its underpinning science community soon responded to the volatile politics of forest land use, and the contemporary debate is now very much focused on implementation of ecologically sustainable forest management principles, with protection of old-growth forest, high conservation value forest and water catchments being rallying points for the environment movement. Whilst the state government maintains that its forest management practices are now scientifically based, the science in fact remains biased towards economic utilisation of forests and many of the assumptions built into the government’s science are questionable. This particularly applies to identification and mapping of old-growth forest.
 
Features of old-growth forest include a predominance of mature and senescing trees, a multi-layered understorey, and habitat for many life forms. Many qualities which characterise old-growth forest are shared with younger forests so it is not possible to define exactly where the boundaries lie. However, for forest management purposes it is necessary to quantify and delineate old-growth forest. It is the narrow arbitrary criteria that was used by the Victorian state government’s environment department (‘the Department’)[1] to meet this goal that is questioned in this report.
 
There are numerous generic definitions of old-growth forest which have emanated from  governments, environment groups, institutions and ecologists. The author has devised his own definition, as follows:
 
               Old-growth forest is a term that signifies the late successional growth stages of a forest ecosystem for which, notwithstanding disturbances, the natural ecological processes continue to occur. (Trevor Poulton 2006)
 
Out of all the generic definitions, the JANIS Definition (Commonwealth of Australia 1997), which is now well entrenched in government agreements, policies and reports, is endorsed in this report as the most obvious and efficacious definition to work under for the purpose of dialogue with the Victorian state government and advancing the old-growth forest debate. The JANIS Definition states:
 
            Old-growth forest is ecologically mature forest where the effects of disturbances are now negligible. (JANIS Definition 1997)
 
The Department refers to the accumulative area containing old-growth forest in Victoria as the ‘old-growth forest domain’. Seeking the optimum protection of this domain requires consensus between the Victorian state government and stakeholders on more accurate and balanced methodologies for identifying old-growth forest. Problems which need to be addressed include:
  What benchmarks ought be applied for identifying old-growth forest for specific forest ecosystems? How can old-growth forest best be identified in the field and mapped? What represents an adequate reserve system for conservation of old-growth forest? What monitoring procedures ought be put in place? 1.1      Old-growth forest and biodiversityForests evolve through various structural growth stages as a result of natural thinning of the younger dominant trees and maturing of others. This aging process is described as stand replacement disturbance. As a portion of the younger trees die off from competition others age and develop hollows that promote biodiversity. The greater the number and diversity of hollows present, the greater is the diversity of faunal species that can occupy them. Biodiversity is increased in older forests which typically have a more heterogeneous structure than younger, more homogeneous-structured forests. If the ecological processes of the forest remain relatively intact and are not undermined by human disturbance or catastrophic natural events, such a forest may be described as ecologically maturing.
 
The article Spatial Aspects of Structural Complexity in Old-growth Forests points out the high levels of structural complexity of old-growth forests:
This complexity includes a large variety of individual structures, such as a broad range of sizes and conditions of live trees, standing dead trees (snags), and boles on the forest floor. Such forests often include other structural features, such as well-developed and often diverse understories and thick forest floors (e.g., Spies et al 1988; Lindenmayer et al 2000).
 
This structural complexity is the key to many distinctive functional and compositional roles played by old-growth forests, such as habitat for biodiversity and regulation of energy and material cycles (e.g. Franklin et al 1981). The diversity of structures and microclimates in an old-growth forest provides niches for a broad array of organisms. These structures constitute significant stores of energy, water, and nutrients and create protected environments that moderate responses to daily, seasonal, and annual fluctuations in environmental conditions.
Franklin and Van Pelt 2004
 
Each growth stage of a forest ecosystem provides unique ecological niches. It is the assemblage of plants and animals occurring in an old-growth forest that is distinctive (Burgman and Lindenmayer 1998). A Wet Forest ecosystem in East Gippsland, for example, that has reached an old-growth stage comprises of highly mature eucalypts such as Errinundra Shining Gum, Messmate, Mountain Ash or Manna Gum. There is usually an understorey of small trees such as Elderberry Panax and Mountain Pepper with a tall shrublayer dominated by plants such as Musk Daisy-bush and Gippsland Waratah and beneath that a dense layer of Soft Tree-ferns and Rough Tree-ferns and a scattering of herbs such as Ivy-leaf Violet. (See DSE Ecological Vegetation Class Bioregion Benchmarks for current DSE descriptions of these vegetation communities).
 
Hollows develop in the more mature trees and, for example, in Wet Forest are used as nests for birds such as Sooty Owls, Yellow-tailed Black Cockatoos and forest bats. Nectar flows and Mistletoe densities increase in the older trees providing nectar and fruit for birds such as the Crescent Honeyeater and possums such as the Yellow-bellied Glider. Stags are used as perching and feeding trees as well as providing basking sites for reptiles such as the Lace Monitor and Diamond Python. Fallen logs provide habitat for amphibians and travel routes for small mammals. The Long-footed Potoroo relies on the growth of fungi out of the decay of logs on the Wet Forest floor as a food source. Spider webs, lichens and mosses are more abundant on mature or dead trees and are critical as nest building materials. (Note - habitat descriptions drawn from Woodgate et al 1994).
 
Old-growth forest is shaped by the physical environment, vegetation and landscape and is not, as often depicted, necessarily composed of towering eucalypts with a moist understorey, but may, for example, comprise of low tree canopy cover and a dry scrubby understorey. 
 
Depending on the forest type, older trees may have hundreds of years beyond their peak before they die, and even then they play an invaluable role as ‘stags’ or standing dead trees, and eventually as coarse woody debris on the forest floor.
 
Industrial disturbance processes such as logging, thinning and high-intensity fuel reduction burns often alter the structure of an older forest resulting in loss of hollows and other animal habitat and loss of biodiversity, impacting on species which rely on the mature ecosystems for feeding, shelter or reproduction. 
 
Hollow bearing trees are a renowned feature of eucalypt forests in their older growth stages. Approximately 31% of all Australian terrestrial mammals, 79% of reptiles, 15% of land birds and 13% of frog species appear to use tree hollows (Lindenmayer & Gibbons 2002).
 
Many Victorian species listed as vulnerable under the Flora and Fauna Guarantee Act (1988) need hollows, for example the Leadbeater’s Possum, Spotted-tail Quoll, Squirrel Glider, Red-tail Black Cockatoo, Powerful Owl and Littlejohn’s Tree Frog. Appendix C of this report provides a list of threatened, hollow-dependent Victorian fauna.

‘Loss of hollow-bearing trees from Victorian native forests’ was listed as a threatening process in the Flora and Fauna Guarantee Act (1988)[2] in 1991[3]. A ‘potentially threatening process’ is defined as ‘a process which may have the capability to threaten the survival, abundance or evolutionary development of any taxon or community of flora or fauna’[4] and is eligible for listing ‘if, in the absence of appropriate management, it poses or has the potential to pose a significant threat to the survival or evolutionary development of a range of flora .... CONT./ .... http://www.forestnetwork.net/PDFs/old-growth-forest.pdf

FNCV Library - Field Naturalists Club of Victoriahttps://www.fncv.org.au/wp-content/uploads/publications/.../fncv-books-18-09-18.pdf - Poulton, Trevor. Defining, identifying and protecting ... Goolengook forest investigation information 2006. FORESTS AND FORESTRY.