Soils and Tree Nutrition Research and Development
in Victorian Plantations
Background to Plantation Establishment in Victoria
As noted by Turner et al. (2004), the lack of a native softwood species in Victoria led to the establishment of small test plantations of softwood species potentially suited for timber production under Victorian soil and climatic conditions. This work commenced as early as 1880. It involved testing of a range of ‘best-bet’ conifer species based on expectations of their performance and productivity in other states like NSW, SA and WA as well as in New Zealand and also in their native habitat in the USA and southern Europe. It was soon discovered that Pinus radiata (Radiata Pine) was most suited to the environmental conditions commonly encountered in southern Australia and this became the dominant species for the rapid expansion of a softwood plantation resource in Victoria and other southern states.
Plantation development in Australia expanded in the early 1960s when the Australian Forestry Council sought Commonwealth funds to support State and Territory funding for a Plantation Extension (PX) program to make Australia self-sufficient in softwood timber in the shortest possible time frame. The PX initiative presented a broad range of research challenges to ensure plantations did not fail but instead were highly productive consistent with the limitations of the range of site types encountered across the country. Soils and nutrition research and development (R&D) played a major role in the ultimate success of this ambitious PX program.
Initial plantations were established almost exclusively on land that had been cleared of native forest for intensive gold mining activity. Many of these denuded sites failed to adequately regenerate naturally on the highly eroded soils in areas around Ballarat, Creswick, Beechworth and Castlemaine. Likewise areas of remnant native forest and scrub were often encountered on land harvested of highly productive Eucalyptus regnans (Mountain Ash) forest to meet the continuing post-war demand for hardwood timber. Many of these denuded areas were then converted to agriculture. In many instances these agricultural pursuits failed and the land was abandoned and reverted back to scrub, particularly in the Otway Ranges and the Strzelecki Ranges. Some of these abandoned farms were reforested with Mountain Ash whilst others were converted to Radiata Pine plantations. The Forests Commission Victoria (FCV) had set ambitious targets for plantation expansion under the PX program, and large areas of native forests on crown land in many parts of the state including north-eastern Victoria, south Gippsland and south-western Victoria were converted to Radiata Pine.
Extensive site appreciation surveys were conducted by skilled and experienced foresters from the Commission to identify areas (mainly in coastal and foothill forests) in targeted regions likely to be suitable for conversion to softwood plantations. The focus of the surveys was on soils (fertility as judged by indicator species, propensity for erosion when cleared), vegetation (forest type), topography and rainfall (total and seasonal distribution). The surveys were constrained by soil classification maps for the native forest estate. Following the surveys, native forests on the foothills around Benalla, Myrtleford, Bright and Shelley in north-eastern Victoria and elsewhere as guided by the surveys were converted to pine plantations. As the PX program progressed, there was increasing public concern however about the loss of native forest ecosystems, especially those with high biodiversity values, to a monoculture of introduced Radiata Pine. Conversion of native forests to pine plantations began to be phased out in the late 1970’s, and the practice was immediately halted following the release of the 1986 Victorian Timber Industry Strategy. Future plantation establishment was confined to cleared land. Cleared farmland judged suitable for Radiata Pine plantations was progressively purchased by Government. The selection of suitable land and the establishment of plantations on such land led to a number of research challenges. In 1988 the Flora and Fauna Guarantee Act was introduced to conserve the biodiversity of native forest ecosystems, reinforcing the directions of the Timber Industry Strategy in relation to plantation development.
Early Stages of Forest R&D
The land available for plantations (mainly coastal and foothill forests) was generally on the poorer soils considered to be unsuitable for agriculture. Growth of Radiata Pine on cleared native forest land was often poor, especially on soils disturbed by gold mining in the past, and plantation failure was not uncommon. The FCV had established a Research and Education Branch in the 1950s as a multidisciplinary group of forestry scientists with an initial focus on investigating problems related to the silvicultural management of native forests, particularly regeneration processes following clear felling. The organisation recognised the importance of R&D in support of forest management and the same approach was taken as part of the plantation expansion (PX) program that commenced in 1961. The initial focus of this research was on tree improvement, nursery practices to produce quality planting stock, site preparation, planting techniques, pests and diseases, and disorders associated with tree nutrition. Research staff were called upon to solve problems related to plant propagation at the various nurseries (e.g. Flinn et al. 1980) and the establishment, growth and management (including pruning regimes) of Radiata Pine plantations.
Survival and early growth of Radiata Pine on the wide range of forest soils encountered was highly variable resulting in a gradient in site productivity and merchantable yields within and between compartments. Failure was often associated with poor soil conditions (compaction, poor drainage, low organic matter) indicating the need for soil cultivation to prepare sites for planting. However early growth was often poor even on the better structured soils indicating that other issues related to soil fertility were most likely limiting tree growth. The rather mixed success of Radiata Pine plantations was not unique to Victoria; similar problems of poor establishment and growth on forest soils were encountered in regions selected for the establishment of softwood plantations in New South Wales, Tasmania, South Australia and Western Australia. It became quite obvious to the Australian Forestry Council that there was a lot to be gained from collaboration between the various State forestry organisations, the CSIRO (Division of Forestry and Forest Products) as well as the forestry schools at the University of Melbourne and the Australian National University.
Research Working Groups covering a range of disciplines, including a Soils & Tree Nutrition Group, were established by the Australian Forestry Council to provide a forum for forestry scientists of the various state organisations, CSIRO and universities to meet, share experiences, and collaborate in finding solutions for problems related to soils and tree nutrition. This Working Group system proved to be highly successful, not only for collaborating scientists but also for timely feedback to the Council on matters of national or regional importance.
Some of the early investigations in NSW and ACT plantations identified low availability of phosphate in native forest soils as one of the likely reasons for poor growth of Radiata Pine. This did not come as a surprise as the paucity of plant available phosphate in the highly weathered soils of Australia was known to be a major limitation for agricultural crops and pastures.
Soils and Tree Nutrition R&D for Plantation Establishment
The first experimental fertiliser trial of the Forests Commission was established in 1950 at Anglesea on a site where the original 1920’s plantation of Radiata Pine had failed. The trial was designed to compare the growth of P. radiata, P. pinaster (Maritime Pine) and P. caribaea (Carribbean Pine) in response to soil cultivation and phosphate fertiliser and was implemented by Max Raupach and colleagues of CSIRO (Division of Soils) and Brian Gibson (FCV, Research Branch). Soil cultivation increased height growth of Radiata Pine by 20% to age 5 years and there was a strong growth response to phosphate fertiliser (superphosphate at 1 t/ha) increasing volume at age 17 from 30 m3/ha to 215 m3/ha (Raupach et al. 1975). This study also showed that volume growth of Radiata Pine was well correlated with levels of phosphorus in foliage indicating the potential of foliage analysis as a diagnostic tool for identifying phosphorus deficiency in pine plantations. Responses of Maritime Pine and Carribbean Pine to cultivation and phosphate fertiliser were more variable and smaller compared with Radiata Pine.
The trial at Anglesea served as an experimental model for further field trials established in the early 1960’s in poorly growing plantations on former mining sites at Scarsdale and Happy Valley to determine growth responses to phosphate fertilisers (Flinn et al. 1979a).
These early trials showed that poor growth of Radiata Pine due to low soil fertility could be diagnosed by foliage analysis and soil testing to identify specific nutrients limiting tree growth. Research in Australia and New Zealand progressively identified levels of key nutrients associated with either satisfactory growth or retarded growth due to one or more nutrient deficiencies. Foliage diagnostic features were also developed to support foliar analysis results. The head of the Research Branch (Ron Grose then followed by John Jack and Fred Craig) recognised the importance of developing such diagnostic tools to determine the nutrient status of pine plantations in need of remedial treatment with fertilisers to improve their productivity. The Research Branch, located in offices at LaTrobe St at the time, commenced work instigated by Fred Craig on the development of analytical procedures for chemical analysis of soils and pine foliage using shared laboratory facilities at the old School of Forestry on Tin Alley at the University of Melbourne. In the meantime new offices and research facilities were built at 1 MacArthur Place (next to the FCV head office at Treasury Place) and the laboratory was equipped with state-of-the-art instruments for physical and chemical analysis of soils, plant tissue and water. This increased the capacity for sample analysis and enabled the development of sampling protocols for the annual monitoring of tree nutrition in research trials and diagnostic testing of pine plantations with suspected nutrient deficiencies based on visual symptoms in the various forest districts in Victoria.
It is noteworthy that in preparation for a possible new plantation estate in Victoria, the FCV established an extensive series of test plots scattered across a wide range of coastal and lowland native forest sites including east Gippsland, south-western Victoria and north-eastern Victoria. These test plots proved exceedingly valuable as foliar samples could be collected and analysed to give advanced notice of possible nutrient deficiencies in each region and soil type.
The research of forest soils and tree nutrition expanded under David Flinn with the installation of a number of trials testing the effects of soil cultivation, weed control and fertiliser on survival and early growth of Radiata Pine on low productivity sites at a number of locations including Scarsdale, Narbethong, Neerim East, Heywood and Rennick.
This work showed strong and often synergistic growth responses to the combination of soil cultivation, chemical weed control and fertiliser and often showed the requirement for follow-up treatment with mostly phosphate fertiliser after 3 to 4 years to maintain the supply of phosphorus to thinning age.
The gains in volume production in response to phosphorus fertiliser applied at planting and age 4 were substantial increasing productivity of Radiata Pine up to five-fold on forest soils low in plant-available phosphate in trials at Narbethong and Neerim East (see graph).
This provided a benchmark for the productive capacity of plantations on similar soil types and was subsequently extended to include other soil types following the change in ownership to Hancock Victorian Plantations Pty Limited (HVP) in 1998. Results for these phosphate fertiliser trials in 1st and 2nd rotation plantations formed the basis for the phosphate response model currently used for the nutrient management of plantations in Victoria.
Second Rotation Decline
In the late 1960s studies in South Australia showed a significant decline in the productivity of second rotation (2R) plantations established mainly on coastal sands. This called into question the long-term sustainability of Radiata Pine plantations on soils of low fertility and the silvicultural regime of burning harvesting residues and intensive soil cultivation to prepare sites for planting the second rotation. Plantations were being established under the FCV’s PX program on similar soils in south-western Victoria and there was concern about the long-term viability of the Radiata Pine resource beyond the first rotation (1R). A research project was established by Fred Craig, David Flinn and Ross Squire (who co-ordinated the study) to determine any 2R decline and investigate an alternative silvicultural regime for coastal sands. Growth of 1R and 2R Radiata Pine was compared on the same sites and on matched sites comparing the original cultural practices (burning and soil cultivation) with an alternative regime of retention of harvesting residues and pit planting aimed at conserving organic matter and nutrients (Squire et al. 1979). This showed better growth of 2R pine with retention of harvesting residues due mainly to higher uptake of nitrogen and lower water stress. It was also shown that burning of harvesting residues resulted in significant losses of organic matter and nutrients, especially nitrogen, from the plantation ecosystem (Flinn et al. 1979b). In due course this work led to the adoption of retention of harvesting residues as standard operational practice for successive rotations of Radiata Pine. The original 2R trials continued to final harvest at age 30 years and showed increased productivity over two rotations (MAI: 21 to 27 m3/ha/yr) largely attributed to the retention of litter and harvesting residues (Hopmans and Elms 2009)
A common assertion by a number of stakeholders has consistently been that pines “ruin” soils and cause soil acidity. This issue has been intensively studied in southern Australia (see Turner et al. 2004). Hopmans et al. 1979 undertook a detailed investigation of chemical properties of sandy soils under pine and native eucalypt forest in south-western Victoria. They found no evidence of pines being associated with soil acidity. Although soils under both ecosystems were very low in organic matter, nitrogen, total phosphorus and exchangeable cations except for calcium (as would be expected on such sandy soils derived from limestone). Soils under pine were found to be higher in some nutrients, although there was some evidence of a decline in phosphorus, calcium and magnesium from the surface horizon. They concluded that there was only a slight overall effect of pine on the nutrient status of the coastal sands after one rotation.
Boron Deficiency of Radiata Pine
Young plantations established on cleared native forest sites in north-eastern Victoria as part of the FCV’s PX program showed a high incidence of ‘die-back’ in the early 1970s, especially during drought years. The symptoms were consistent with boron deficiency observed in other pine species and foliage analysis of Radiata Pine with ‘die-back’ in cleared bays and healthy trees in heaped windrows confirmed that the symptoms were associated with boron deficiency. Subsequent trials in 2-year-old pine showed that trees treated with a broadcast application of borax recovered and remained free of ‘die-back’ to canopy closure when within stand recycling of nutrients commences and the net demand on soil boron decreases (Hopmans and Clerehan 1991). Early treatment with boron fertiliser was adopted as standard practice for the silvicultural management of Radiata Pine in north-eastern Victoria.
Impact of Conversion to Radiata Pine on Water Quality and Yield of Forested Catchments
Plantations at Myrtleford and Bright were often established on steep land cleared of native forest and there was considerable public concern about soil erosion and the potential deterioration of water quality affecting the water supply of down-stream users of the Ovens River. This prompted the FCV in 1973 to establish the Cropper Creek Hydrology project comprising three 1st order catchments of native forest in the Black Range at Dandongadale. The catchment weirs and gauging equipment were installed by Leon Bren and this forest hydrology project became his life-time occupation. After a three year calibration period of the three eucalypt catchments, one of the catchments was converted to Radiata Pine retaining a 30 m wide undisturbed buffer zone of native forest along the stream channel (Bren et al. 1979). Conversion was found to have little impact on stream water quality and exports of nutrients and suspended solids increased mainly due to higher stream flow following clearing of native forest (Hopmans et al. 1987). A study of nutrient inputs in rainfall and outputs in stream water was conducted prior to clearing as part of a benchmark nutrient budget for small forested catchments (Flinn et al. 1979c). Such data are an important input for determining the sustainability of pine plantations. Subsequent studies at Cropper Creek examined the impacts of thinning and fertiliser on water quality; this again showed short-term changes in water quality (6 to 12 months) and demonstrated the importance of the buffer zone in protecting water quality values (Hopmans and Bren 2007). (
The next stage of the project was to determine the effects of harvesting the plantation and the establishment of the next pine rotation on stream flow dynamics, water yield, water quality and nutrient and sediment export. Unfortunately in December 2006 the three catchments were completely burnt by wildfire including the buffer zone of the pine catchment. The plantation was salvage logged and replanted with Radiata Pine in 2007. This major fire disturbance changed the hydrologic behaviour of the catchments for several years and in the logged catchment resulted in significant soil erosion, deterioration in water quality and large sediment losses. The impacts of wildfire and salvage logging declined over three years and water quality returned to pre-fire values over this period both in the plantation and native forest catchments (Smith et al. 2011 and 2012). The Cropper Creek Forest Hydrology project started by FCV in 1973 then continued by the Department of Conservation, Forests and Lands (DCFL) and successor organisations and more recently by Hancock Victorian Plantations in collaboration with the current School of Ecosystem and Forest Sciences at the University of Melbourne. This long-term project has provided a wealth of knowledge on forest hydrology and the effects of plantation management and the impact of wildfire on stream flow, water quality and nutrient and sediment export in comparison with native forest.
Stem Deformity in Plantations on Farmland
From the late 1970s onwards farm properties, mostly grazed pastures in close proximity of existing plantations and processing facilities, were purchased to establish pine plantations using the same practices as developed for cleared forest land. Plantations on improved pastures were fast-growing providing effective weed control and appropriate site preparation practices were followed, but of very poor form with trees showing lack of apical dominance, numerous thick branches and twisted stems. The visual symptoms resembled copper deficiency; however treatment with copper did not alleviate these symptoms. Furthermore there was strong genotypic variation in the expression of stem deformity as shown in a Radiata Pine progeny trial on improved pasture (Pederick et al. 1984). A joint investigation of possible causes of stem deformity of pine on pastures with the University of Melbourne showed significant differences in soil fertility and in particular availability of soil nitrogen compared with native forest sites; however there was little difference in nutritional physiology of straight and deformed trees (Turvey et al. 1993). Subsequent trials showed that stem deformity could be induced in straight trees on a former native forest site by nitrogen fertiliser applied at high rates (Hopmans et al. 1995). New progeny trials on pastures confirmed consistent genotypic variation in the expression of stem deformity (Bail and Pederick 1989). This enabled the selection of a ‘High-Fertility’ breed of Radiata Pine for cutting propagation to raise planting stock for pasture sites and therefore provided a practical solution to the problem; however the actual physiological cause of stem deformity remains unknown.
Institutional Restructures and Forest R&D
The early 1980s saw a major restructure of Government departments responsible for the management of natural resources including the FCV, Lands Department and the Soil Conservation Authority (SCA). The Department of Conservation, Forests and Lands (DCFL) was formed with the intention of pooling expertise from the well-established institutions like the FCV into groups with a common interest in managing natural resources. The forest research branch was transferred to the building formerly occupied by the SCA on Cotham Rd, Kew. In 1993/94, the research branch was transformed into the Centre for Forest Tree Technology (CFTT) with David Flinn as the Director and Peter Hopmans assumed responsibility for the soils and nutrition R&D program on plantations and native forests. David’s vision for CFTT was to maintain in the longer term a team of multidisciplinary scientists and skilled technical services required by Government and industry in the management of natural and plantation forests in Victoria and beyond. This required a strategy to secure a significant portion of funding requirements from the private sector (including Japanese Trading Houses) and Commonwealth agencies along with service agreements with the Department for research and technical services. Accordingly, CFTT was set up as a Business Unit within what had now become the Department of Conservation and Natural Resources - DCNR (the business name was registered with the Corporate Affairs Office on 26 April 1993) with a view of attracting more external funding to support and add value to research funding from DCNR (in its first year of operation, CFTT attracted over $600,000 in revenue from external consulting and research services). The development of CFTT was overseen by an Advisory Board chaired by Richard Rawson, Director of the Forest Service. Richard was exceedingly supportive of CFTT from the time of its inception to the day he retired.
To meet the new requirements of CFTT, laboratory facilities and general working conditions were improved and the R&D continued for several years until maintenance funds dried up and it became apparent that the building at Kew was going to be sold. In a pre-emptive strike David Flinn moved CFTT to the empty second floor of the Arthur Rylah Research Institute at Heidelberg where it stayed until 2004. For the first time in the history of Forest R&D in Victoria, CFTT directed a lot of time in securing Commonwealth Government and private funding for overseas projects. This was a very successful initiative, with significant contracts for research being awarded to the Centre for forestry projects in countries including Pakistan, China and Indonesia. It lifted the profile of the Institute and gave participating scientists and technicians of forest research institutes in the host countries a challenging but rewarding experience. It also enhanced the skills of participating CFTT staff, which benefited a range of Victorian Government studies.
CFTT used its resources to service the scientific and technical needs of the Forest Service and the Government and at the same time efficiently deliver quality research and consulting services to the private sector. There was an expectation that the expertise of CFTT, which was progressively becoming strongly oriented towards plantation forestry, would stimulate increased private sector investment in plantation forestry in Victoria. There is convincing evidence that this objective was accomplished for the new hardwood plantation estate.
The Research and Education Branch of FCV and subsequently CFTT had a long history of a close and beneficial relationship with the School of Forestry at the University of Melbourne. In the late 1990s Ian Ferguson and David Flinn had a number of informal meetings canvassing the possibility of the two entities forming a strategic alliance. Such an alliance would inter alia significantly broaden the expertise base for basic and applied research, provide enhanced academic opportunities, provide industry and Governments with vastly improved research and development services, improve technology transfer and increase opportunities for funding of forest and ecological services from Commonwealth agencies, State Governments, and local and overseas industrial organisations operating in natural and plantation forests.
In early 1998, Ian Ferguson and David Flinn met with Gerard O’Neill, Executive Director of the Forest Service in what by now was the Department of Natural Resources and Environment (DNRE) and recommended the formation of a strategic alliance between the two entities. A Memorandum of Understanding (MOU) for the formation of the alliance was drawn up and ratified by DNRE and the University of Melbourne. The MOU with a five-year life stated inter alia:
- The objective of the alliance would position the new centre as a major force within Australia and the Asia Pacific region in applied and strategic research on forest issues by better meeting training and research needs of policy makers and other clients in an integrated manner.
- Staff transferring to the Centre would continue to be employed by the two parties on their current terms and conditions.
- Associate Prof. David Flinn would be appointed as Interim Director for 6 months from the date of commencement of the Centre.
In 1999, there was a Government wide downsizing of staff. Few sections were exempt from this directive and CFTT lost nine positions as part of this process. In the absence of the alliance, CFTT would have been below critical mass. This further vindicated the formation of the new Centre.
The new Centre was given the name as the Forest Science Centre to be based at Creswick. To this end, DNRE agreed to fund new laboratories and office space at Creswick. This was accomplished in late 1999 and provided the campus with world class facilities.
On 15 March 2004, Prof. Kwong Lee Dow, Vice Chancellor of Melbourne University, wrote to the Secretary of the then Department of Sustainability and Environment (DSE) confirming that the two parties had agreed on the establishment of the Forest and Ecosystem Sciences Institute (FESI) to replace the FSC. The University also accepted responsibility for the site at Creswick and that the responsibility for the Crown land will transfer to the University. Prof. Lyndsay Neilson, Secretary of DSE, signed off on these and other proposals in the March 2004 letter.
Forest research capacity collapsed at State and Federal levels across Australia in the early to mid 2000s. Whilst FESI has also lost positions over the last few years, it remains a viable Institute to provide strategic R&D services to policy makers and industry on a wide range of disciplines.
Record of Forest Research in Victoria
The work carried out by the Research Branch of FCV since the early 1970s was recorded in numerous internal reports, published technical papers and bulletins covering virtually all projects in plantations and native forest. As an example, 350 Research Branch Reports were written between March 1971 and March 1992. A significant number of these internal reports were published in peer-reviewed journals. Indeed, a heavy emphasis was always given to external publication of appropriate reports and presentation of papers at national and international conferences. This systematic reporting of R&D was instigated by Fred Craig who appointed a scientific editor to maintain a uniform high quality of reporting of forest research for distribution within FCV. This system of reporting R&D was maintained by David Flinn who was in charge of forest research during the successive institutional changes over the next two decades. The numerous reports produced over almost 40 years became an exceptional record of forest research in Victoria. The importance of this work was recognised by the Bureau of Resource Sciences who funded the preparation of a ‘Compendium of Forest Research in Victoria’ as a record of the historic R&D that formed the knowledge base of forest management in Victoria (Murphy et al. 1998). A similar document was prepared in 2011 by Turner et al. titled Management of Victoria’s publicly-owned native forests for wood production: A review of the science underpinning their management. This 216-page report is an excellent example of how an extensive and sustained R&D program enabled the native forest estate to be managed according to well established scientific principles. It greatly assisted VicForests in obtaining certification.
Plantations for Environmental Services
In the early 1980s the Ministry of Water Resources and Water Supply together with regional water authorities in northern Victoria wanted to evaluate tree plantations as an alternative to crops and pastures for the recycling of municipal effluent and wastewater and engaged DCFL to investigate. Large-scale irrigation trials were established at four sites of regional sewage authorities along the Murray River by Hugh Stewart and David Flinn to compare survival and early growth of seven species (Stewart and Flinn 1984). This showed that eucalypt species including Flooded Gum (E. grandis), River Red Gum (E. camaldulensis) and Southern Blue Gum (E. globulus) were the most successful but also indicated the importance of soil type and chemical characteristics of irrigation water for the selection of species. A more detailed study was carried out at Wodonga to determine the accumulation of nutrients in tree biomass by seven species including Radiata Pine and the changes in soil chemistry after four years of irrigation with municipal effluent (Stewart et al. 1990). Tree growth was rapid under the irrigation regimes, however the recovery of nitrogen in tree biomass was relatively low indicating that trees are more suited to effluents low in nitrogen. Soil pH, salinity and sodicity increased while changes in other soil properties were relatively small. This showed the need to schedule irrigation and salt loads to maintain soil properties within an acceptable range for trees.
In the early 1990s a CFTT research program was initiated by Jim Morris in collaboration with other agencies to investigate the feasibility of tree plantations on farms to mitigate the degradation of agricultural land due to soil and groundwater salinity. A large trial was established near Gigarre in northern Victoria to determine water use and salt accumulation by River Red Gum and River She-oak (Casuarina cunninghamiana) and the impact on the shallow water table and soil salinity (Morris and Collopy 1999). This work showed the potential of plantations of salt-tolerant tree species for lowering water tables on salt affected farm land.
This research on irrigated tree plantations by CFTT and similar studies by CSIRO led to the establishment of the Trees for Profit Research Program, a joint initiative of DCNR, CSIRO, the University of Melbourne, the Rural Water Commission and the Treecorp Group. A Trees for Profit Board was formed to oversee a new Trees for Profit Research Centre located at the University of Melbourne. Barrie Dexter was appointed Executive Director of the Centre to amongst other things liaise with all participating parties including landholders, the Board and Research Centre staff, and to identify potential funding sources. The program was co-ordinated by the CFTT Director in close consultation with the Executive Director. The charter was to investigate the possible role of tree plantations in reducing soil and groundwater salinity in this region of the Murray-Darling Basin and simultaneously creating a plantation resource for commercial purposes. To this end, a series of pilot sites were established on freehold land owned by enthusiastic farmers at Cobram, Undera, Zeerust, Mangalore, Nathalia, Tatura, Timmering and Shepparton. Each site tested a range of tree species irrigated with wastewater of varying quality (Bren et al. 1993). The focus of this ambitious R&D initiative was to develop the technology to establish and manage commercial tree plantations for environmental benefits and wood production on farm land affected by salinity and rising water tables. CFFT staff including Tom Baker, Des Stackpole and Jim Morris established irrigation trials with commercial eucalypt species at eight of the pilot sites around Shepparton to determine growth in response to irrigation with effluent, agricultural drainage water and fresh water and to define optimum thinning and pruning regimes for high-value timber production (Baker et al. 2005). Water use was measured at several locations and the data combined with results from earlier trials of CFTT and CSIRO to define the critical factors of climate, soil conditions and water management influencing tree water use and the growth of plantations in the dry regions of the Murray-Darling Basin (Morris and Benyon 2005).
Privatisation of Radiata Pine Plantations
In 1993 the Government established the Victorian Plantations Corporation (VPC), a state-owned enterprise responsible for the management of plantations on a commercial basis in preparation for the privatisation of the plantation resource. In 1998 the state-owned Radiata Pine plantations (including the IP) were sold to Hancock Natural Resources of Boston, USA and the new company (Hancock Victorian Plantations, HVP) engaged CFTT (and later FSC) as the R&D provider based on annual Service Agreements. Plantation R&D became more closely aligned with HVP’s management objectives for the softwood resource with emphasis on the impact of R&D on stand productivity, merchantable yields and financial returns. The primary aim was to optimise the productivity of existing plantations through improved genetics and silvicultural management including site preparation, weed control and fertilisers as well as the management of pests and diseases. Soils and nutrition R&D was a major focus for HVP.
Optimising Plantation Productivity
Past soils and tree nutrition R&D was largely focused on the diagnosis and remedial treatment of nutrient deficiencies at an early age to improve growth to first thinning. Thinning changes the stand dynamics, it reduces inter-tree competition for nutrients and water and opens up the canopy for crown expansion of the retained trees. Earlier studies in Victoria, New South Wales and South Australia showed that application of nitrogen immediately after thinning stimulates the production of foliage biomass and promotes stem growth provided the availability of water and other nutrients are not limiting. This provides an opportunity to enhance the growth and productivity of older plantations and further R&D on this topic was given high priority. A number of trials were established across the HVP estate to determine growth response to fertilisers applied after first and second thinnings (T1 and T2). This showed that post-thinning responses to nitrogen fertiliser were well correlated with the pre-treatment nutrient status. Therefore levels of nitrogen in foliage were a good indicator of the responsiveness of stands and could be used for the selection of thinned stands for treatment. This work also showed that responses on some sites were adversely affected by deficiencies of other nutrients such as sulphur and copper. Furthermore growth and responses to fertiliser were also affected by foliage losses caused by infestations of the Monterey pine aphid (Hopmans and Elms 2013). Infestations of this pine aphid are now common in plantations in south-eastern Australia and therefore stand selection for post-thinning promotion of growth with fertiliser should take into account the nutrient status as well as crown health of trees in order to optimise responses.
The research on soils and tree nutrition started by FCV in the 1960s and continued during the 1980s marked a decade of institutional changes before ownership of the plantations was transferred to HVP who built onto the existing knowledge base. This has transformed the nutrient management of plantations using foliage diagnostic testing at an early age and after thinning to determine tree nutrient status and the requirement for fertiliser. Soils and tree nutrition research by FCV and its successors and continued by HVP has made a significant contribution to the recent development of fertiliser response models for Radiata Pine plantations (May et al. 2017) to predict growth responses, merchantable yields and financial returns for the optimisation of wood production.
In more recent times, there has been a trend towards site-specific management in Australia and beyond. Essentially, this involves having good information on soils and local geology so that a regime of site preparation, weed management and fertilisers can be prescribed to optimise productivity on each site type.
There has been widespread and consistent criticism by a broad range of stakeholders that pine plantations were inter alia ‘ruining’ soils, reducing long term stream flow, impairing water quality and having significant impacts on fauna. Whilst Radiata Pine growers used the best available science to debate these issues, there were no standards upon which stakeholders and growers could refer to. In the early 2000s, Standards Australia established a Steering Committee and appointed a Technical Reference Committee to guide the development of an Australian Forestry Standard. The Technical Committee had wide representation of all stakeholders covering social, cultural, economic, environmental, industry and other relevant groups. David Flinn was the Independent Forest Scientist on this broad ranging Committee. The Committee worked tirelessly to draft Australian Standard – Forest Management-Economic, social, environmental and cultural requirements for wood production. This became known as The Australian Forestry Standard. The objective of the Standard was to provide forest managers and owners with economic, social, environmental and cultural criteria and requirements that support the sustainable management of forests for wood production. It was the first time in the history of forestry in Australian where all stakeholders had a common base upon which to objectively judge whether plantations and natural forests were being well managed.
To be certified under the Standard, forest management must meet all requirements grouped under nine Criteria. In the development of the Standard, particularly for Criterion 4 relating to maintaining productive capacity of plantations and Criterion 6 relating to protection of soil and water resources, the soils and nutrition R&D undertaken in Victoria played a key role in formulating requirements to be met under these two Criteria and associated Criteria. In particular, the 1R/2R study, the extensive field experiments investigating the interaction between site preparation, weed management and fertilisation provided guidance on the efficient and responsible use of chemicals (including fertilisers) in the environment.
Requirements that must be met to be certified relating to soils and nutrition include:
- Management actions must not compromise the productive capacity of the plantation area.
- Establishment (regeneration) of plantations must be effective and timely.
- Identify and assess the inherent soil and water values that can be adversely affected by plantation operations.
- Maintain the protective and productive functions of the plantations through good management of factors such as erosion, chemical pollutants and contaminants that effect a range of important soil and water properties including soil biology, soil structure and fertility, and water quality and steam flows.
- Minimize any nutrient loss.
The first plantations to be certified in Australia was the HVP estate in 2003. Smartwood undertook the certification assessment. A broad based audit team including David Flinn undertook the assessment. Smartwood developed its own Standard which drew heavily on the Draft Australian Forestry Standard which in turn drew heavily on Victorian Plantation R&D over a lengthy period. During the audit process, many stakeholders were critical of HVP management practices associated with chemical weed control, fertilisation practices, site preparation procedures and impacts of plantation activities on stream flow and water quality. But for the R&D undertaken by FCV on these and related issues, it is doubtful if HVP would have been certified. However, HVP was able to demonstrate that it met most of the Criteria under its nine Principles (AFS used Criteria and Requirements as opposed to Principles and Criteria of Smartwood, but as would be expected they both had similar requirements to be met for certification).
Certification is now widely used to satisfy stakeholder needs and confirm that wood is being sourced from “sustainably“ managed forests. A more appropriate description however is that the certification process demonstrates that certified forests and plantations are being “well managed” and are going down the path of continuous improvement.
[This report was drafted by Peter Hopmans who offered David Flinn the opportunity to contribute. David added a couple of new sections to complete the story of soil science and tree nutrition R&D conducted by FCV and later by the amalgamated Departments.]
Baker T, Duncan M, Stackpole D (2005) Growth and silvicultural management of irrigated plantations. In 'New forests: Wood production and environmental services'. (Eds S Nambiar and I Ferguson) pp. 113-134. CSIRO Publishing, Collingwood, Australia.
Bren LJ, Flinn DW, Hopmans P, Leitch CJ (1979) 'The hydrology of small forested catchments in north eastern Victoria: 1. Establishment of the Cropper Creek project.' Forests Commission Victoria, Melbourne. Bulletin No 27, pp. 48.
Bren L, Hopmans P, Gill B, Baker T, Stackpole D (1993) Commercial tree-growing for land and water care 1: Soil and groundwater characteristics of the Pilot Sites. Report to the Trees for Profit Research Board, pp. 46.
Soils and Tree Nutrition R&D of Plantations in Victoria May 2019
Flinn DW, Bren LJ, Hopmans P (1979c) Soluble nutrient inputs from rain and outputs in stream water from small forested catchments. Australian Forestry 42, 39-49.
Flinn DW, Hopmans P, Craig FG (1980) Survey of the nutrient status of Pinus radiata seedlings and of soil properties in three Victorian nurseries. Australian Forestry 45, 58-66.
Flinn DW, Hopmans P, Farrell P, James JM (1979b) Nutrient loss from the burning of Pinus radiata logging residue. Australian Forest Research 9, 17-23.
Flinn DW, Moller IM, Hopmans P (1979a) Sustained growth responses to superphosphate applied to established stands of Pinus radiata. New Zealand Journal of Forestry Science 9, 201-211.
Hopmans P, Bren LJ (2007) Long-term changes in water quality and solute exports in headwater streams of intensively managed radiata pine and natural eucalypt forest catchments in south-eastern Australia. Forest Ecology and Management 253, 244-261.
Hopmans P, Clerehan S (1991) Growth and uptake of N, P, K and B by Pinus radiata D. Don in response to applications of borax. Plant and Soil 131, 115-127.
Hopmans P, Elms SR (2009) Changes in total carbon and nutrients in soil profiles and accumulation in biomass after a 30-year rotation of Pinus radiata on podzolized sands: Impacts of intensive harvesting on soil resources. Forest Ecology and Management 258, 2183-2193.
Hopmans P, Elms SR (2013) Impact of defoliation by Essigella californica on the growth of mature Pinus radiata and response to N, P and S fertilizer. Forest Ecology and Management 289, 190-200.
Hopmans P, Flinn DW, Squire RO (1979) Soil chemical properties under eucalypt forest and radiata pine plantations on coastal sands. Forestry Technical Papers 27, Forests Commission, Victoria, pp. 15-20.
Hopmans P, Flinn DW, Farrell PW (1987) Nutrient dynamics of forested catchments in south-eastern Australia and changes in water quality and nutrient exports following clearing. Forest Ecology and Management 20, 209-231.
Hopmans P, Kitching M, Croatto G (1995) Stem deformity in Pinus radiata plantations in south-eastern Australia.2. Effects of availability of soil nitrogen and response to fertiliser and lime. Plant and Soil 175, 31-44.
May B, Elms S, Hopmans P, McKay L, Hetherington S, Bruce J, Edwards K, Hanssen R (2017) 'ProFert - Pine: A fertiliser tool for softwood plantations in southern Australia.' Report PNC342-1415, Forest and Wood Products Australia, Melbourne, Australia, pp. 87.
Morris J, Benyon R (2005) Plantation water use. In 'New forests: wood production and environmental services.' (Eds S Nambiar and I Ferguson) pp. 75-104. CSIRO Publishing, Collingwood, Australia.
Morris JD, Collopy JJ (1999) Water use and salt accumulation by Eucalyptus camaldulensis and Casuarina cunninghamiana on a site with shallow saline groundwater. Agricultural Water Management 39, 205-227.
Soils and Tree Nutrition R&D of Plantations in Victoria May 2019
Murphy S, Polak-Scowcroft C, Coy R (1998) Compendium of Forest Research in Victoria: Published, unpublished and research in progress. Bureau of Resource Sciences, Department of Primary Industries and Energy, Canberra, Australia, pp. 275. (ISBN 0-642-47505-9)
Pederick LA, Hopmans P, Flinn DW, Abbott ID (1984) Variation in genotypic response to suspected copper deficiency in Pinus radiata. Australian Forest Research 14, 75-84.
Raupach M, Clarke ARP, Gibson BF, Cellier KM (1975) 'Cultivation and Fertilizer Effects on the Growth and Foliage Nutrient Concentrations of P. radiata, P. pinaster and P. caribaea on Three Soil Types at Anglesea (Victoria).' CSIRO, Division of Soils, Technical Paper No. 25, pp. 20.
Smith HG, Sheridan GJ, Lane PNJ, Bren LJ (2011) Wildfire and salvage harvesting effects on runoff generation and sediment exports from radiata pine and eucalypt forest catchments, south-eastern Australia. Forest Ecology and Management 261, 570-581.
Smith HG, Hopmans P, Sheridan GJ, Lane PNJ, Noske PJ, Bren LJ (2012) Impacts of wildfire and salvage harvesting on water quality and nutrient exports from radiata pine and eucalypt forest catchments in south-eastern Australia. Forest Ecology and Management 263, 160-169.
Squire RO, Flinn DW, Farrell PW (1979) Productivity of first and second rotation stands of radiata pine on sandy soils. I. Site factors affecting early growth. Australian Forestry 42, 226-235.
Stewart HTL, Flinn DW (1984) Establishment and early growth of trees irrigated with wastewater at four sites in Victoria. Forest Ecology Management 8, 243-256.
Stewart HTL, Hopmans P, Flinn DW, Hillman TJ (1990) Nutrient accumulation in trees and soil following irrigation with municipal effluent in Australia. Environmental Pollution 63, 155-177.
Turner J, Flinn D, Lambert M, Wareing K, Murphy S (2011) Management of Victoria’s publicly-owned native forests for wood production: A review of the science underpinning their management, Forest and Wood Products Australia, Project Number PRC 147-0809, pp. 216.
Turner J, Wareing K, Flinn DW, Lambert M (2004) Forestry in the Agricultural Landscape: A review of the science of plantation forestry in Victoria. Dept. Primary Industries, Victoria, pp. 56.
Turvey ND, Downes GM, Hopmans P, Stark N, Tomkins B, Rogers H (1993) Stem deformation in fast grown Pinus radiata - an investigation of causes. Forest Ecology and Management 62, 189-209.