Sustainable management of native and exotic plantations in Australia JOHN TURNER1, STANLEY P. GESSEL2† and MARCIA J. LAMBERT1 1 FORSCI Pty. Ltd., Beecroft, New South Wales, Australia; 2 College of Forest Resources, University of Washington, Seattle, WA, USA († passed away)
Key words: establishment, Eucalyptus, fertilization, monitoring, Pinus radiata Abstract. The emphasis of plantation management changes as the resource and the market develop. This is especially the case when a plantation program is developing a new timber resource, is not the case with many of the Pinus radiata (D. Don) plantings in the southern hemisphere. Australia establishes and manages plantations of both exotic conifer and native hardwood (Eucalyptus spp.) plantations, and these vary in their stage of development. The tenure and objectives in establishment have varied, but some key aspects of the resources may be analyzed. Optimization of production per unit area was not a prime objective during the developmental stages of many exotic pine plantations. Currently, with increased commercial emphasis, this has changed to a greater focus on increased value through Site Specific Management and tree improvement through which gains of at least 20 percent are expected during the first stages. With a key objective of sustainability, questions regarding impacts of soils, water, and biological changes need consideration and are being addressed. The eucalypt plantation resource in Australia is smaller in extent than is the pine resource, but of increasing importance, especially as the plantations are perceived to be more environmentally and ecologically acceptable than exotic conifers. In the past, questions of productivity, especially in relation to impacts of natural pests and diseases, have been raised. Sustainability of all plantations is a critical aspect, however, for specific issues there are different emphases with different species. For example, the relatively, high removal of calcium in smooth barked Eucalyptus plantations is seen as important in long term forest management.
Introduction Countries in the southern hemisphere have initiated significant establishment programs of fast-growing, forest plantations for timber production. In many cases, the plantations have been established with the primary purpose of producing forest products for the future, whereas for others there also was the objective of alleviating pressure on native forests for timber production to allow them to be managed for other values. There are now in excess of 15 million ha planted, about 9 million ha of which are coniferous with the [ 377 ]
18 Table 1. Areas of coniferous and hardwood plantations in 1993 in the southern hemispherea . Region Country
Area (1,000 ha) Coniferous Hardwood
Total Australasia Australia New Zealand
2,362 960 1,378
163 123 22
2,525 1,083 1,400
Total South America Brazil Chile
5,419 3,383 1,385
4,509 3,617 215
9,928 7,000 1,600
Total Africa South Africa
a Only countries with the larger areas of plantings have been listed individually.
remainder hardwood (Table 1). The coniferous plantings are dominated by Pinus radiata (D. Don) with smaller areas of southern and Caribbean pines. Hardwood plantings have primarily been of the genus Eucalyptus, native to Australia, with the bulk consisting of Eucalyptus grandis Hill ex Maiden, E. globulus Labill., and E. nitens (Deane & Maiden) Maiden. Except for the establishment of plantations of Eucalyptus within Australia, plantations in the southern hemisphere are composed of exotics. The selection of species for planting has generally been made on the basis of rapid growth and the suitability of the timber for an industrial market. A relatively minor component of the overall area of southern hemisphere plantations is in Australia (Table 1), but the area is expanding as a result of the demand for timber, especially softwoods, and pressure to reduce utilization of native forests. The aim of this paper is to present an analysis of some planting programs in Australia, to consider the impacts of research, and to indicate how the objectives of management and community acceptance change over time. The differing perspectives of exotic pine and native eucalypt plantations will be compared, together with the problems involved in maintaining a sustainable resource, by using plantations within New South Wales as a case study indicator. A central issue is whether or not plantations are sustainable, and this raises the question as to what attributes are to be sustained. Although this question may be addressed in terms of the original objective for establishing [ 378 ]
19 the plantation, there are further evolving expectations. This paper considers that the more intensive the intended management (e.g., in terms of inputs or site specificity) for whatever purpose, the greater the requirement for technical information and monitoring. Historical perspective Pine plantings commenced in Australia in 1876 (Carron 1985) to overcome shortages of softwood timber, there being only limited natural softwood resources within Australia (e.g., Araucaria). The first plantings in New South Wales were in 1914 on very poor coastal sands at Tuncurry (Black 1948). There was a perception that many of the Pinus species could be planted on depauperate soils and that rainfall, and subsequently mycorrhizae, were the primary limiting factors to growth. Although the efforts of researchers such as Stoate (1950) and Ludbrook (1942) showed the critical nature of soils and nutrition, especially in relation to the heavily weathered and often low phosphorus soils in Australia, their findings took considerable time to be incorporated into forest management. The results of these perceptions were some significant failures in plantation establishment and, even when it was recognized that nutrition was critical, there was a lengthy period when the concept of the “small quantity, quick fix” fertilizer application abounded. This concept was derived primarily from the impact on growth of small quantities of zinc applied to P. radiata on limited areas within South Australia (Stoate 1950). In the 1960s, intensive research commenced on nutrients, especially phosphate deficiency, in Australian soils. The work indicated the strong influence of soil parent material on phosphorus availability, this allowing initial soil classification on the basis of nutritional status (for example, Humphreys and Gentle 1967; Humphreys et al. 1975), the magnitude of the response obtained on poorer sites, and the length of the response on some sites extending into subsequent rotations (Gentle et al. 1965, 1986). Adsorption of applied phosphate was subsequently determined and the soils on which responses to applied phosphate could be expected were defined (Ellis et al. 1975; Flinn et al. 1979; Turner 1982; Turner and Lambert 1986). The magnitude of these responses could be substantial, but only on very specific sites. However, prediction of response from site factors and foliage analysis was relatively easy (Lambert and Turner 1988). This ameliorative type of fertilizer application, although important initially, became relatively minor compared to site establishment and midrotation applications aimed at optimizing financial gain (Turner and Knott 1991). Subsequently, the critical relationships among soil parent material, location with respect to nutrient inputs [ 379 ]
20 (for example, maritime or industrial), and deficiencies of boron and sulfur became apparent (Humphreys et al. 1975; Lambert 1986; Lambert and Ryan 1990). Until the post-World War II period, plantations tended to be established on poor soils or locations undesirable for agricultural pursuits, and often were established to alleviate unemployment or to support such small-scale industries as case manufacture. That is, the decisions for establishing plantations were not made primarily on an economic basis. Subsequently, an analysis was made of the cost to the nation of importing timber and the policy was proposed and accepted that Australia become self-sufficient in timber requirements. This led to the Commonwealth Softwood Agreement (Anonymous 1967). Loan funds were provided by the Commonwealth to the States for plantation establishment and land was acquired and planted; usually native forest was converted to pine plantations. However, there was minimal appreciation of site conditions, genetic properties, or establishment techniques, and there were few environmental constraints. Establishment of large areas became the main measure of success without real assessment of cost effectiveness or return. Much of the establishment of plantations was on sites being converted from native forest or woodland, and serious environmental opposition began to appear against this in the 1970s, particularly on state-owned land (Routley and Routley 1975). On economic grounds, government agencies responsible for planting resisted the pressure to stop planting on native forest sites, because the land being cleared was essentially free; the alternative was the purchase of cleared freehold land. During this period in South Australia, further cheap suitable land became less available and the State was moving into a second rotation establishment program. Second rotation productivity declines, supporting the arguments of Routley and Routley (1975) that exotic plantations were not sustainable, were reported (Keeves 1966), and this was viewed with great concern within the pine planting industry. The soils in question were coarse-textured infertile sands where loss of organic matter, through increased decomposition or burning, had serious consequences, and they were shown to require specific management procedures to maintain nutrients and organic matter (Flinn et al. 1980; Farrell et al. 1981). However, this was not as critical for much of the planting area in Australia where soils are higher in clays and derived in situ from parent materials. A large proportion of early plantings was on sandy soils, but this was changing over time with a greater emphasis on relatively more fertile soils (Turner and Lambert 1991). The attempt to optimize the major components, namely site, genetics, and management inputs, involved in optimum plantation output to produce a specific product has been termed “Site Specific Management.” During [ 380 ]
21 the 1980s, the combination of environmental pressures, commercialization of Forest Services, reduced land availability, and the development of more sophisticated markets led to greater concentration on Site Specific Management to optimize productivity and financial returns from sites. There have been significant pressures to reduce or stop planting exotic species, particularly P. radiata. Forest managers now need, not only to reinforce that wood is a renewable crop, but also to provide evidence that this is so, e.g., through the use of appropriate indicators. The use of Site Specific Management also needs to be further evaluated in conjunction with potential environmental effects. Eucalyptus plantations are a much smaller component of the Australian plantation resource than are pine plantations, and their development is more sporadic. These plantations have usually been used to fulfill an objective within a market, such as a pulpwood deficit. Pine plantings involve an introduced species for which there are few detrimental biological agents (predominantly they are subject to Sirex and Dothistroma), and the site interactions directly affect growth. Eucalypts are native species with many endemic pests and diseases, thus resulting in both direct and indirect impacts on productivity and value. Extension of a species away from its natural site conditions can induce stress directly affecting growth or indirectly affecting growth through biological agents. Long-term plantations have been perceived to have a much higher risk than pulpwood rotations. Despite this, eucalypt plantations are perceived by some groups, ecologists and others, as being more environmentally appropriate for Australia. The bulk of recent plantings have focused on short rotations for pulp production. Programs are now extending the plantings, but there is a need to match sites to species. Present Australian plantation resource Pine plantation areas were extended primarily after World War II and today there are in excess of 1 million ha planted. Very recent planting rates have exceeded 30,000 ha/yr (ABARE 1994). The areas (Table 2) indicate a concentration on P. radiata and reductions in some other coniferous species. The proportion of eucalypts has changed from about 4 percent of the total planted area to 11 percent, and this is expected to continue to increase. Nationally, plantation site characteristics and species composition are changing over time. Pinus radiata is about 66 percent of the plantation resource, but is decreasing slightly. Of the other pine species, P. caribaea More. is increasing in relative importance (Table 2), whereas other coniferous species are decreasing (that is, on conversion to second rotation, these species are being replaced with others). The greatest relative increase is in [ 381 ]
22 Table 2. Plantation areas (1986–1993) in Australia according to species (Source: ABARE 1994). Species
Area in 1986 (ha) (% of total)
Area in 1993 (ha) (% of total)
Net annual change (ha/yr)
Conifers Pinus radiata Pinus elliottii Pinus pinaster Pinus caribaea Araucaria spp. Other Total conifers
Broadleaved species Eucalyptus spp. Populus spp. Other Total broadleaves Total
36,265 2,262 2,013 40,540 872,712
3.8 0.3 0.2 4.3 100
123,489 1,277 3,053 127,819 1,082,711
the eucalypt plantation resource which from 1986 to 1993 expanded from 3.8 percent of total plantation area to 11.4 percent. In 1970, approximately 33 percent of the plantation resource was established on transported sands (Table 3), such as those on which second rotation decline had been reported (Keeves 1966). However, by 1990 this had declined to 26 percent as increased plantings occurred on soil developed in situ, with higher clay contents and higher buffering capacities.
Site-specific management in pine plantations To date, the Site Specific Management approach has been specifically applied to Pinus plantations, but it can be used with reference to any plantation and any desired mix of products (i.e., timber, water, soil amelioration, and aesthetics). This recognizes that sites differ in responsiveness, and that there are considerable difficulties in extrapolating results from one site to another. The objective is to optimize the output of a specified product in order to maximize [ 382 ]
23 Table 3. Proportion of Pinus radiata plantation areas in Australia in 1970 and 1990 on soils derived from different parent materials. Codea (PRC)
Note: Total area = 423,935 ha and 993,965 ha in 1970 and 1990, respectively. a Soil parent material codings (Parent Rock Codes as described by Turner et al. 1990; Turvey et al. 1990). b Typical example of rock types under the Parent Rock Code (Turner et al. 1990).
return, value, or other measure of output (for example, water quality). The product in most plantations at present is usually clear sawn wood, but it may be any defined product. Site Specific Management requires the classification and ready identification of sites. This has been developed to the greatest level of sophistication for P. radiata. The system, when appropriately applied, recognizes climate as the major overriding factor, followed by soil and previous land use. Climatically, P. radiata is limited to temperate areas with rainfall in excess of 800 mm. (Southern or Caribbean pines are grown in more subtropical and tropical areas.) Soil classification has involved the development of a specific Soil Technical Classification System for P. radiata, and the primary factor is soil parent material, which has been classified into twelve major groupings subdivided into either in situ or transported (Turner et al. 1990; Turvey et al. 1990). The technical classification system has been found to categorize sites into productivity units and, more critically, into potential to respond to management treatments. It also provides a basis for identifying sites with potential nutrient problems (Knott and Ryan 1990; Turvey and Smethurst 1994a,b). Sites have been shown to vary significantly in productivity (Knott and Ryan 1990). For example, at age 20 years, productivity on soils derived from rhyolitic parent material (PRC 8) was on average less than 40 m 2 /ha basal [ 383 ]
24 Table 4. Effect of previous land use on stem volume and log quality of a 20-year-old stand of Pinus radiata (Source: Birk 1991). Stand parameter
Previous land use
Volume (m3 /ha) High Quality Logs (stems/ha) Nonutilizable Index (%) Mineralized Nitrogen (kg/ha/yr)
346 350 12 38
431 42 44 86
area, whereas it was more than 55 m2 /ha on soils derived from basaltic and granodiorite parent materials (PRC 9 and PRC 11). Alternative management treatments include application of fertilizers at the time of establishment and after thinning (Turner et al. 1992, 1996), but other issues such as treatment for disease may be included. Previous land use provides additional refinement to the classification system, because it can have an effect on productivity and timber utilization. For example, where the previous land use has been improved pasture (that is, the addition of phosphatic fertilizers plus the addition of leguminous crops to cleared land), increased levels of mineral nitrogen are found, which lead to extensive stem deformity and branching (Birk 1991; Downes and Turvey 1992). The effect can increase total productivity, but deformity greatly reduces utilization and value (Table 4). The classification of site allows for the identification of risk involved in plantation management, including both risks to productivity and utilization and those which can be related to environmental aspects such as erosion (Lacey et al. 1994). Such management can increase returns per unit area, but, more critically, can increase the whole project value by identifying sites to be rejected from plantation establishment. However, there are interactions between previous land use and soil parent material that result in direct effects on absolute productivity (Table 5). This indicates the necessity to consider multiple factors and to relate information on the potential for sites to respond to change. On the lightly buffered sands (Table 5), there has been little change from the effect of pasture improvement, especially when compared to the major differences in productivity resulting from previous land use on soils derived from basalt and sedimentary parent materials. In addition to identification of site effects, there have been very substantial and ongoing gains as a result of genetic improvements. These improvements have had the greatest impact on plantations in the last decade, and the effect [ 384 ]
25 Table 5. Comparison of productivity of Pinus radiata grown on sites with differing prior land use (Source: Skinner and Attiwill 1981). Soil parent material
Basalt Basalt Sediments Deep sand
Stand age (yr)
15 18 18 24
Volume MAI (m3 /ha/yr)a with previous land use Native forest
15.3 9.8 10.7 20.3
25.8 22.1 17.8 21.1
68.6 125.5 66.3 3.9
a Volume MAI is not directly comparable between sites because of differences in stand age.
Table 6. Increases in growth in Pinus radiata plantations from a combination of breeding and silvicultural developments applied to large-scale plantations (Source: Nambiar 1995). Main soil type
Average MAI (m3 /ha/yr) 1950–1971 1975–1982
Range in realized gain (%)
Gradational clay loam Duplex soil Uniform sand
1,150 750 650
16.2 9.1 8.0
6–58 35–59 33–107
23.8 14.2 15.1
is increasing. The work for P. radiata has been carried out primarily through cooperatives, both within Australia and in cooperation with New Zealand. The value of these development programs has included the ability to focus on a limited number of desirable attributes (growth, straightness, branching), and there have been a variety of demonstrations of this in routine plantations (Table 6). The issue for managing sustainably is that of identifying realized gains from such factors as tree improvement compared to actual changes in site and environmental effects.
Environmental effects of intensive management Conversion of native forests to plantations will lead to soil changes, such as reduction in organic matter and nitrogen (Turner and Kelly 1985). The effects of increased intensity of management of conifer plantations can result in impacts on site and other environmental attributes. Although nutrient removals may be considered to have long-term impacts, major concerns relate to the potential for increased soil erosion and compaction (Lacey 1993). [ 385 ]
26 Such impacts can be identified and managed, but the actual management requirements will be site specific. More significant impacts are related to the use of water and the ability to manage long-term water requirements in terms of water quality and quantity. Conversion of previous grassland to plantation results in a greater water demand by the crop and it has been estimated that, where a high proportion of a catchment area has been converted to forest plantation, water yield may be reduced by up to 40 percent (Cornish 1989). Although this reduction may not be critical in high rainfall areas, it could be significant in more marginal areas (Turner and Lambert 1987). Conversion of native forest to faster growing forest can be expected to result in increased water use, but the extent of this will be less than where there is a change in land use. Based on a water use efficiency factor of 0.002 g organic matter/g water used, each cubic meter of wood per hectare in a radiata plantation will require approximately 40 mm of water. Without estimating all factors (for example, interception), an increase of 10 percent in the growth of a plantation with an existing mean volume annual increment of 20 m3 /ha (at 30 years) will increase annual water demand by 80 mm, and reduce runoff accordingly. Effects on water quality as a result of increased sedimentation will not be associated with higher productivity per se, but greater management activity on the area could have such an effect.
Eucalyptus plantings Whereas there are only a limited number of species of conifers in the Australian planting program, there are a relatively large number of eucalypt species, including E. camaldulensis Dehnh., E. cloeziana F. Muell., E. globulus, E. grandis, E. laevopinea R. Baker, E. maculata Hook., E. nitens, E. pilularis Smith, E. regnans F. Muell., and E. saligna Smith. This diversifies efforts in terms of research and management practices, and reduces gains in comparison to those achieved from P. radiata or P. caribaea. There has been a range of trials demonstrating the site specificity of some species and the general adaptability across sites of others. As an example, on a nutritionally poor site in New South Wales, a eucalypt species trial provided results for a selection of species (Table 7). Eucalyptus dunnii Maiden can grow on relatively better topographical positions, whereas E. fastigata Deane & Maiden grows moderately well in a range of situations. Eucalyptus pilularis is broadly successful and E. maculata and E. saligna are site selective. Apart from raising the issue of the requirements for comprehensive trial designs, this shows the range in performance of different species. [ 386 ]
27 Table 7. Estimated basal area of selected Eucalyptus species at age 18 years on four topographical locations on a nutritionally poor site in New South Wales (Source: Johnson and Stanton 1994). Speciesa
a Ordered according to increasing productivity on the “gully” sites.
Eucalypts have been found to be very responsive to cultural treatments, such as site preparation, weed control, fertilizer application, and even insecticide treatment (Cromer and Williams 1982; Birk and Turner 1992; Stone 1993). Total biomass of a E. grandis plantation at 9 years without treatment was 123 t/ha. With intensive fertilizer treatment this was raised to 175 t/ha, and with intensive fertilizer treatment plus weed control and insecticide this was increased to 274 t/ha (Birk and Turner 1992). The effects of interactions among species, fertilizer use, and insect control were shown for E. grandis and E. dunnii (Stone 1993). With no insecticide treatment, E. dunnii produced statistically greater growth at 26 months of age (7.0 cm diameter) compared to the diameter growth of 6.5 cm in the treatment in which insecticide was applied. The response to fertilizer was the same, whether or not insecticide was applied (9.8 cm and 9.5 cm, respectively). Eucalyptus grandis gave a greater response when insects were controlled in an insecticide treatment (5.4 cm and 6.8 cm without and with insecticide, respectively), and particularly when fertilizer was applied (5.6 cm with no control of insects, and 10.0 when insecticide was applied). A combination of particular eucalypt species which have high nutrient concentrations and rapid growth can lead to high nutrient accumulations in the tree component. There is potential for high nutrient removals with harvesting of rapidly grown eucalypt plantations, especially for the nutrient calcium. This is primarily a result of high calcium concentrations in bark, especially for the smooth barked species (Lambert 1981; Lambert and Turner 1991). More than 60 percent of the ecosystem calcium was found in the above[ 387 ]
28 ground components for 27-year-old E. grandis (Turner and Lambert 1983; Lambert and Turner 1991). It has been suggested that P. radiata substantially drains nutrients from sites (Crane and Raison 1980); however, the related impacts associated with E. grandis plantations indicate a greater potential for calcium loss in eucalypt plantations. The long-term impacts of such changes on sustainability have not been measured to date. Sustainability of plantations The primary objective with current plantations has been to maximize productivity, yield, and value. The basis for the objective has been lack of resource for certain products and for investment. Objectives are now changing to include site amelioration (especially high water tables), mixed products, enhancement of farming land, and water quality/quantity issues. Whatever the objective, including reducing pressure on utilization of native forests, plantations require higher inputs. Recognition of greater potential productivity, range of products, and value in plantations is balanced by a greater potential for site deterioration and loss in value as a result of increasingly more intensive management practices. For example, as discussed earlier for eucalypt plantations, there is a high risk of nutrient depletion, especially for the cations, and so higher levels of technical knowledge and precision are required in management. The questions raised earlier were whether or not plantations are sustainable and which attributes need to be sustained. Where the objective is to maintain production of timber at a predetermined level and quality, it should be achievable, but there are costs in the process of doing this and these costs must be recognized. Increasing productivity, by whatever means (e.g., genetics, higher operational inputs), will necessitate a cost, for example, reduced water production. However, unlike management of natural forests, there is a greater chance of estimating both costs and benefits of plantations. In the forest management triangle, the outputs are determined by the management of the site, genetics, and management inputs. Thus, Product = (Genetics)(Site)(Management). If, over successive rotations, the genetic stock is actually improved (for example, a volume improvement of 30 percent) but site factors are reduced through compaction, there could be a net volume decrease (for example, by 20 percent) with constant management inputs. The net increase in productivity is measured as 4 percent, but this is misleading because the site is in fact deteriorating. In intensively managed plantations this interaction needs to be separated out and understood. It is critical to obtain the potential in production. [ 388 ]
29 Monitoring requirements The more intensively plantations are managed, the greater the potential for increasing yield and value, but there is also increased risk for environmental or productivity-generated problems. Two types of monitoring, sustainability indicators and performance, are required. Monitoring of sustainability indicators Sustainability indicators provide information on the actual characteristics of forests and how they are changing under routine management. The objective is to utilize parameters which are indicators of processes within the system. The factors which need to be addressed within intensively managed plantations differ from those associated with more extensive natural forests. They include the following: • Actual productivity measures (for example, biomass and value). • Assessments of yield (harvested products). • Impacts of pests and diseases. • Environmental changes (for example, in water quality). • Changes in soil properties (including changes over rotations). Performance monitoring Where there is investment, there needs to be an assurance that gains are being achieved. To do this, the individual processes (site impacts, genetics, and management) need to be addressed. These are the following: • Changes resulting from genetic changes. • Effects of compaction and results of amelioration (site preparation). • Effects of fertilizer/herbicide usage. • Effects of pest/disease control measures. • Changes in wood quality. Many other factors will overlap independently with sustainability, but the difference will relate to investment. Whereas research experiments can provide information on potential effects, there is often a substantial fall down in measured effects when implemented operationally, and hence effectiveness may not be understood without appropriately designed systems (that is, performance monitoring allows for estimates of fall down to be made). The research carried out on site, on species selection and improvement, and on management inputs to fast-grown plantations shows that great gains can be obtained in productivity, and that the potential impacts can be measured. However, there have to be systems in place which will ascertain whether or not the gains are being realized, [ 389 ]
30 and which will enable impacts to be offset. It is this area of monitoring and interpretation at the management level that requires further research.
References ABARE (Australian Bureau of Agricultural and Resource Economics). 1994. Quarterly Forest Products Statistics. Commonwealth of Australia, Canberra. Anonymous. 1967. Softwood Forestry Agreements Bill. Commonwealth of Australia, Canberra. Birk, E.M. 1991. Stem and branch form of 20-year-old radiata pine in relation to previous land use. Aust. For. 54: 30–39. Birk, E.M. and Turner, J. 1992. Response of flooded gum (E. grandis) to intensive cultural treatments: Biomass and nutrient content of eucalypt plantations and native forest. For. Ecol. Manage. 47: 1–28. Black, R.M. 1948. The history of the Pinus plantations in New South Wales. Forestry Commission of New South Wales Forest Recorder 1: 30–37. Carron, L.T. 1985. A History of Forestry in Australia. Australian National University Press, Canberra. Cornish, P.M. 1989. The effects of radiata pine plantation establishment and management on water yield and water quality – a review. Forestry Commission of New South Wales Technical Paper No. 49. Forestry Commission of New South Wales, Sydney. Crane, W.J.B. and Raison, R.J. 1980. Removal of phosphorus in logs when harvesting Eucalyptus delegatensis and Pinus radiata forests on short and long-term rotations. Aust. For. 43: 253–260. Cromer, R.N. and Williams, E.R. 1982. Biomass and nutrient accumulation in a planted Eucalyptus globulus (Labill.) fertilizer trial. Aust. J. Bot. 30: 265–278. Downes, G.M. and Turvey, N.D. 1992. Stem deformation in Pinus radiata. University of Melbourne, School of Forestry Research Bulletin 8. University of Melbourne, Melbourne, Australia. Ellis, R.C., Neilsen, W.A., McDavitt, J.G. and Thirkell, D.S. 1975. Early growth of radiata pine in relation to a land classification system on Forestier Peninsula in Tasmania. Aust. For. 37: 245–257. Farrell, P.W., Flinn, D.W., Squire. R.O. and Craig, F.G. 1981. On the maintenance of productivity of radiata pine monocultures on sandy soils in south-east Australia, pp. 117–128. In: Proceedings of the Seventeenth International Union of Forest Research Organisations Congress. International Union of Forest Research Organisations, Kyoto, Japan. Flinn, D.W., Moller, I.M. and Hopmans, P. 1979. Sustained growth responses to superphosphate applied to established stands of Pinus radiata. N. Z. J. For. Sci. 9: 201–211. Flinn, D.W., Squire, R.O. and Farrell, P.W. 1980. The role of organic matter in the maintenance of site productivity on sandy soils. N. Z. J. For. 25: 229–236. Gentle, S.W., Humphreys, F.R. and Lambert, M.J. 1965. An examination of a Pinus radiata phosphate fertilizer trial fifteen years after treatment. For. Sci. 11: 315–324. Gentle, S.W., Humphreys, F.R. and Lambert, M.J. 1986. Continuing response of Pinus radiata to phosphatic fertilizers over two rotations. For. Sci. 32(3): 822–829. Humphreys, F.R. and Gentle, S.W. 1967. Experience with phosphatic fertilizers in man-made forests of Pinus radiata in New South Wales. In: Symposium on Man-made Forests. Canberra, Australia.
[ 390 ]
31 Humphreys, F.R., Lambert, M.J. and Kelly, J. 1975. The occurrence of sulphur deficiency in forests, pp. 154–162. In: McLachlan, K.D. (Ed.) Sulphur in Australasian agriculture. Sydney University Press, Sydney. Johnson, I.G. and Stanton, R.R. 1993. Thirty years of eucalypt species and provenance trials in New South Wales – survival and growth in trials established from 1961 to 1990. Forestry Commission of New South Wales Research Paper No. 20. Forestry Commission of New South Wales, Sydney. Keeves, A. 1966. Some evidence of loss of productivity with successive rotations of Pinus radiata in the south-east of South Australia. Aust. For. 30: 51–63. Knott, J. and Ryan, P. J. 1990. Development and practical application of a soils database for Pinus plantations of the Bathurst Region. Forestry Commission of New South Wales Research Paper No. 11. Forestry Commission of New South Wales, Sydney. Lacey, S.T. 1993. Soil deformation and erosion in forestry, a review. Forestry Commission of New South Wales Technical Report. Forestry Commission of New South Wales, Sydney. Lacey, S.T., Ryan, P.J., Huang, J. and Weiss, D.J. 1994. Soil physical property change from forest harvesting in New South Wales. State Forests of New South Wales Research Paper No. 25. State Forests of New South Wales, Sydney. Lambert, M.J. 1981. Inorganic constituents in wood and bark of New South Wales forest tree species. Forestry Commission of New South Wales Research Note No. 45. Forestry Commission of New South Wales, Sydney. Lambert, M.J. 1986. Sulphur and nitrogen nutrition and their interactive effects on Dothistroma infection in Pinus radiata. Can. J. For. Res. 16: 1055–1062. Lambert, M.J. and Ryan, P.J. 1990. Boron nutrition of Pinus radiata in relation to soil development and management. For. Ecol. Manage. 30: 45–53. Lambert, M.J. and Turner, J. 1988. Interpretation of nutrient concentrations in Pinus radiata fertilizer at Belanglo State Forest. Plant Soil 108: 237–244. Lambert, M.J. and Turner, J. 1991. Nutrient cycling processes in Eucalyptus grandis forests on the New South Wales north coast, pp. 198–199. In: Ryan, P.J. (Ed.) Productivity in Perspective. Forestry Commission of New South Wales, Sydney. Ludbrook, W.V. 1942. Fertilizer trials in southern New South Wales pine plantations. J. CSIRO Aust. 15: 307–314. Nambiar, E.K.S. 1995. Relationships between water, nutrients and productivity in Australian forests: Application to wood production and quality. Plant Soil 168–169: 427–435. Routley, R. and Routley, J. 1975. The Fight for the Forests. Research School of Social Sciences, Aust. Nat. University, Canberra. Skinner, M.F. and Attiwill, P.M. 1981. The productivity of pine plantations in relation to previous land use. I. Growth responses in agricultural and forest soils. Plant Soil 60: 161–176. Stoate, T.N. 1950. Nutrition of the Pine. Forest and Timber Bureau Bulletin 30. Forest and Timber Bureau, Canberra. Stone, C. 1993. Fertilizer and insecticide effects on tree growth and psyllid infestation of young Eucalyptus grandis and Eucalyptus dunnii plantations in northern New South Wales. Aust. For. 56: 257–263. Turner, J. 1982. Long term superphosphate trial in regeneration of Pinus radiata at Belanglo State Forest, N.S.W. Aust. For. Res. 12: 1–19. Turner, J. and Kelly, J. 1985. Effect of radiata pine on soil chemical characteristics. For. Ecol. Manage. 11: 257–270.
[ 391 ]
32 Turner, J. and Knott, J. 1991. Prescribing fertilizers in New South Wales plantation forestry. In: Forest Fertilization: Sustaining and Improving Nutrition and Growth of Western Forests. College of Forest Resources, University of Washington, Seattle. Turner, J. and Lambert, M.J. 1983. Nutrient cycling within a 27-year-old Eucalyptus grandis plantation in New South Wales. For. Ecol. Manage. 6: 156–168. Turner, J. and Lambert, M.J. 1986. Fate of applied nutrients in a long-term superphosphate trial in Pinus radiata. Plant Soil 93: 373–382. Turner, J. and Lambert, M.J. 1987. Nutritional management of Pinus radiata at Gurnang State Forest, New South Wales. Fert. Res. 13: 127–137. Turner, J. and Lambert, M.J. 1987. Forest water usage and interactions with nutrition of Pinus radiata. Oecol. Plant. 8: 27–44. Turner, J. and Lambert, M.J. 1991. Changed perspectives on soil processes associated with the changed land base of plantation forestry in Australia, pp. 15–28. In: Ryan, P.J. (Ed.) Productivity in Perspective. Forestry Commission of New South Wales, Sydney. Turner, J., Thompson, C.H., Turvey, N.D., Hopmans, P. and Ryan, P.J. 1990. A soil technical classification for Pinus radiata (D. Don) plantations. I. Development. Aust. J. Soil Res. 28: 797–811. Turner, J., Lambert, M.J., Bowman, V. and Knott, J. 1992. Two post thinning fertilizer trials in Pinus radiata in New South Wales, Australia. Fert. Res. 32: 259–267. Turner, J., Knott, J. and Lambert, M.J. 1996. Fertilization of Pinus radiata plantations after thinning. I. Productivity gains. Aust. For. 59: 7–21. Turvey, N.D. and Smethurst, P.J. 1994a. Soil types as classes for managing the nutrient status of planted Pinus radiata in Victoria, Australia. Aust. For. 57: 148–156. Turvey, N.D. and Smethurst, P.J. 1994b. Nutrient concentrations in foliage, litter and soil in relation to wood production of 7- to 15-year-old Pinus radiata in Victoria, Australia. Aust. For. 57: 157–164. Turvey, N.D., Booth, T.H. and Ryan, P.J. 1990. A soil technical classification system for Pinus radiata (D. Don) plantations. II. A basis for estimation of crop yield. Aust. J. Soil Res. 28: 813–824.