Adapted by S.A. Dembner
Note: This article is adapted from a study undertaken in 1993/94 by the Australian Bureau of Agricultural and Resource Economics: Survey of trees on Australian farms: 1993-94, by S.M. Wilson J.A.H. Whitham, U.N. Bhati, D. Horvath and Y.D. Tran. ABARE Research Report 95.7. Canberra, ABARE.
With an emphasis on planted trees, this article analyses farmers' perceptions of the influences that trees have on farms in Australia.
Thirty-five percent of farmers surveyed had planted trees in the past three years
The actual and perceived impact of trees on farmland is an important element of the overall discussion on forest influences. Trees can bring various on- and off-farm benefits. They may, for example, promote the sustainability of natural resources, provide shelter and shade for livestock and produce a range of timber and non-timber products to supplement agricultural income.
In Australia, a range of private and government programmes have emerged to encourage tree planting on farms, including the One Billion Trees Programme, the Community Rainforest Reforestation Programme and elements of the National Landcare Programme as well as private and joint ventures. However, there is still only limited information on the extent of tree plantings on Australian farms and on farmers' perceptions of the costs and benefits of these plantings. To help fill the information gap, the Australian Bureau of Agricultural and Resource Economics (ABARE) surveyed approximately 2 000 agricultural crop and dairy farmers across Australia in 1993/94. The aim of the survey was to collect a range of financial and physical data to assist both in developing and refining programmes to promote tree planting on farms and in developing research and extension models of agroforestry systems. A further aim of the survey was to help state governments allocate funds for tree planting to those areas which would potentially benefit most from improved natural resource management or nature conservation.
The study considered farms in three agricultural zones based on the predominant form of land use: the pastoral, wheat/sheep and high rainfall zones (see Box).
The 2 000 farms considered represented only a small proportion of Australian farms. However, they were selected on the basis of a framework provided by the Australian Bureau of Statistics that consists of an annual listing of key characteristics and industry information for all of the country's agricultural establishments with an estimated value of agricultural operations of $A 22 500 or more, and were sufficient to ensure a representative, statistically valid national coverage.
The study focused on farmers' perceptions of tree planting on agricultural land. However, baseline data were also collected on natural forests and woodlands (at least 10 percent crown cover) located on agricultural land. Farmers were asked about the area and main function of natural forests and woodlands on their farms and also whether they intended to clear any of this vegetation during the next five years (through 1999). Seventy-four percent of the farms in the pastoral zone had natural forests and woodlands and 35 percent had forest land that was either cleared or partially cleared. The average area of cleared or partially cleared forest land in the pastoral zone was 1 138 ha per farm, representing 1.5 percent of the average operated area of these very large farms. About 81 and 68 percent of farms in the wheat/sheep and high rainfall zones, respectively, had some areas of native forest or woodland. The average area of this natural woody vegetation was 348 ha per farm in the wheat/sheep zone and 163 ha per farm in the high rainfall zone. These areas represented 18 and 20 percent of the average operational farm areas in these two zones, respectively.
Characteristics of Australia's three agricultural zones
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Characteristics of Australia's three agricultural zones PASTORAL ZONE The pastoral zone includes the arid and semi-arid regions of Australia and is characterized by land used predominantly for grazing livestock on natural pastures. While some cropping is undertaken in this zone, an inadequate and unreliable rainfall makes it Impractical on most farms. The farm size in this zone is very large, often more than 100 000 ha. WHEAT/SHEEP ZONE The wheat/sheep zone is characterized by land which is suitable for regular cropping in addition to the grazing of livestock at a higher intensity than in the pastoral zone. The rainfall and tomography are generally suitable for producing a range of pasture species, often in rotation with crops. The average far m size is much smaller than that in the pastoral zone. HIGH RAINFALL ZONE The high rainfall zone consists of all of Tasmania, the majority of the coastal belt and adjacent tablelands of Victoria, New South Wales and Queensland as well as small parts of southeastern South Australia and southwestern Western Australia. The land in this zone is used predominantly for intensive livestock production because the higher rainfall steeper topography and higher humidity make it less suitable than the wheat/sheep zone for agricultural cropping. |
Of the many potential functions of natural forests and woodlands in Australian farming, the provision of shelter and shade was the most commonly reported function in all states. Other functions listed were the conservation of native vegetation and wildlife and treatment to prevent soil degradation. The surveyed farmers rarely mentioned the production of pulpwood, sawlogs and non-timber products for sale as the main function of their forests and woodlands.
The percentage of farmers who expressed an intention to clear some of their natural forest and/or woodland areas within the five-year period from 1994/95 to 1998/99 varied widely among states and agricultural zones. The highest percentages of farmers planning to clear were in Queensland's pastoral and wheat/sheep zones (an estimated 23 and 27 percent, respectively). However, since the survey, the Queensland State Government has proposed new guidelines on land clearing. Farmers in Victoria, Western Australia, South Australia, Tasmania and the Northern Territory expressed, on average, an intention to clear less than 5 percent of their native forests and woodlands. Unfortunately, the survey does not allow conclusions to be drawn regarding the motivation for forest clearing.
About two-thirds of managed plantings were tree belts or corridors
As noted in the introduction, the main purpose of the study was to collect data on tree planting, rather than on the management (or clearance) of natural forest. First, farmers were asked to provide information about planted trees on their farms, regardless of when they had been established. Then they were also asked for information about recent plantings. The two types of information permit a simple comparison of recent tree planting with the extent of tree planting over a longer period.
Asked whether there were any planted trees on their farms, 35 percent of farmers responded that they had tree belts and corridors, 14 percent had tree blocks, 6 percent had alley belts (at least two strips of trees with grazing or cropping between the strips) and another 6 percent had widely spaced plantings. Average areas of the tree belts and corridors, tree blocks and alley belts were 5, 12 and 10 ha, respectively. The average number of widely spaced planted trees was 406 per farm.
The farmers were asked to list up to three main functions of their planted trees. In the wheat/sheep and high rainfall zones, the most common functions listed were the provision of shelter and shade, the treatment or prevention of soil degradation and the conservation of natural vegetation and wildlife. In the wheat/sheep zone in Western Australia, land rehabilitation and protection was the most common function (81 percent), well above the national average for the wheat/sheep zone (58 percent). This may reflect the farmers' response to the region's susceptibility to land degradation problems, particularly dryland salinity. Results for the pastoral zone are not presented because there were insufficient sample points with planted trees in this zone.
Planting trees to produce timber or non timber products for sale was of relatively minor importance at the national level. However, in the high rainfall zones of Queensland and South Australia there were frequent plantings for the production of sawlogs and, in Western Australia and Tasmania, there were numerous pulpwood production plantings.
Recent tree plantings
Thirty-five percent of farmers surveyed had planted trees in the previous three years (1991/92-1993/94). Western Australia and Victoria had the highest percentages of recent tree planting (57 and 50 percent, respectively) while Queensland and the Northern Territory had the lowest (6 and 4 percent). Of the total recent plantings, about two-thirds were tree belts and corridors, were composed of predominantly local native species and were meant for providing shelter and shade. Tree blocks accounted for a further 20 percent of recent plantings, with an average area of just over 5 ha per planting. Alley belts and widely spaced trees averaged between 3.8 and 5.7 ha per planting and accounted for only 8 and g 9 percent of the plantings, respectively. Nearly three-quarters of the plantings were established on arable land. Seventy-three percent were within 100 km of the nearest timber mill, but only 6 percent of the total plantings were intended for harvesting. The estimated small population of farmers indicating an intention to harvest planted trees for timber suggests that it may be worthwhile conducting further studies into the feasibility of commercial tree plantations on agricultural enterprises. Potential barriers may include low farm cash incomes, high debt levels, a lack of technical and economic information, a lack of suitable markets and uncertainty about being permitted to harvest trees.
Establishment costs
To estimate the cost of establishing trees on farms, farmers were asked to provide costs information regarding their most recent plantings. The information collected included tractor and labour requirements, fencing and other material costs, contract expenses (both cash and in kind) and the total value of financial assistance received. The results show tree blocks to be the most costly to establish, at about $A 1 815 per hectare, followed by tree belts and corridors ($1 048), alley belts ($1 042) and widely spaced trees ($689). These costs compare unfavourably with those identified in a number of previous economic studies (Stephens and Hansard, 1994; Thorne, 1991; Trapnell and Lavery, 1989; Moore, 1991; and Bulman, 1991). However, it is noteworthy that the previous studies generally used cost assumptions not based on on-farm sources; some referred to large-scale tree plantings in areas particularly suited to forestry for commercial purposes and they often did not consider fencing costs (one of the most expensive elements in on-farm tree planting).
Reasons for not planting trees
About 27 percent of the farmers with some planted trees on their farms did not plant additional trees in the three years preceding the survey. Of those farmers, 37 percent felt they already had enough trees and 28 percent did not plant because of the high costs of establishment. A small proportion of farmers also listed the low establishment success rate and the poor relative profitability as reasons for not planting. These results coincide with those of Prinsley (1991).
Farmers who had planted trees on their farms, but not from 1991/92 to 1993/94, gave a number of reasons for not planting during this period. The two most common reasons were that their farms already had enough trees and that establishment costs were too high.
Management of planted trees
About one-third of the farmers with planted trees on their farms indicated that they regularly carried out management operations on these trees (including weeding, fertilizing, thinning, pruning, fencing, watering and controlling pests, diseases and fires). About two-thirds of the managed plantings were tree belts or corridors. Tree blocks, alley belts and widely spaced tree plantings were generally not managed intensively.
The average annual costs of management operations conducted on the most recently managed stands of trees were $A677 per 100 trees for tree belts and corridors, $460 per hectare for alley belts, $318 per hectare for widely spaced trees and $220 per hectare for tree blocks. These estimates should not be confused with average annual management costs over the entire expected life of the trees.
Benefits from farm trees may be obtained in many ways. Trees may provide indirect benefits for farms through the provision of shelter and shade for livestock or the amelioration of land degradation problems such as soil erosion and high water tables. Trees may also provide a wide range of direct benefits through the production of commercial products such as fuelwood, sawntimber and posts and poles where appropriate growing and market conditions exist. These benefits, jointly or separately, are likely to feature significantly in farmers' decisions as to whether or not to plant trees on their farms. A central aim of this study was to investigate the perceived direct and indirect benefits of planted trees.
Direct benefits
All surveyed farmers in the field crop and dairy industries were asked whether they had harvested any products from planted trees on their farms from 1991/92 to 1993/94 (Table 1, p.20). Their responses show that the proportion of the farmers who harvested trees during this period was nil in the pastoral zone, 1 percent in the wheat/sheep zone and 6 percent in the high rainfall zone. Nationally, the figure was only 3 percent, indicating that only a small segment of the agricultural crop and dairy farming population was involved in harvesting commercial products from its trees during the three-year period.
More than 85 percent of the plantings that were harvested from 1991/92 to 1993/94 were tree blocks or tree belts and corridors. Sixty-eight percent of harvested plantings in the high rainfall zone but only 13 percent in the wheat-sheep zone were situated on arable land. Nationally, 68 percent of the harvested plantings served mainly to provide shelter and shade, while 25 percent were mainly for producing sawlogs for sale.
There were insufficient sample points to generate statistically significant information on the harvesting costs, the products harvested and the gross income received from the sale of these products.
Indirect benefits
All surveyed farmers in the agricultural crop and dairy industries were asked to assess the indirect benefits of their mature trees - that is, their largest plantings of each of the four planting regimes that were over ten years of age (Table 2).
The perceived impact of mature plantings on the rate of soil erosion varied with the type of planting regime. The surveyed farmers reported that the presence of mature trees reduced soil erosion on farms. The percentage of plantings that decreased the rate of soil erosion was 41 percent for tree blocks, 18 percent for alley belts, 25 percent for tree belts and corridors and 67 percent for widely spaced trees. These results may appear to support the conclusion of Bird et al. (1991) that wind erosion is likely to be dramatically reduced by the presence of trees on farms.
In many cases, farmers also reported that the rise in the water table on their farms was being slowed, stabilized or reversed by their mature trees. This positive impact was greatest under tree blocks and alley belts, at 42 and 40 percent, respectively, and least under tree belts and corridors, at 24 percent (Table 2). In several other cases, however, respondents reported that their mature e trees were having no impact on water table levels. This lack of impact was most frequent under widely spaced trees (40 percent) and least frequent under tree blocks (29 percent).These results indicate that farmers' perceptions of the impact of mature trees on water table levels vary considerably across Australia, although this probably reflects the geographical dispersion of farms with problems concerning the water table. The results also indicate that higher-density plantations are generally perceived to have a greater impact on water table levels than lower-density plantations.
TABLE 1. Characteristics of the most recently harvested stand of planted trees 1
|
|
Wheat/sheep zone |
High rainfall zone (Percentage) |
Australia |
|
Farmers who harvested products from planted trees, 1991/92-1993/94 |
1 (67) |
6 (31) |
3 (28) |
|
Type of planting harvested ² |
|||
|
Tree block |
87 (70) |
39 (45) |
42 (40) |
|
Alley belt |
0 (nd) |
14 (ns) |
13 (ns) |
|
Tree belt and corridor |
13 (ns) |
47 (44) |
45 (44) |
|
Widely spaced trees |
0 (nd) |
0 (nd) |
0 (nd) |
|
Type of tree species in the harvested planting ² |
|||
|
Predominantly local native species |
100 (nd) |
21 (83) |
26 (62) |
|
Predominantly other native species |
0 (nd) |
52 (34) |
48 (34) |
|
Predominantly exotic species |
0 |
27 (2) |
25 (2) |
|
Main function of harvested planting ² |
|||
|
Land rehabilitation or protection |
0 (nd) |
0 (nd) |
0 (nd) |
|
Shelter and shade |
0 (nd) |
73 (14) |
68 (14) |
|
Native vegetation and wildlife conservation |
87 (70) |
0 (nd) |
6 (70) |
|
Sawlog production |
0 (nd) |
27 (39) |
25 (39) |
|
Pulpwood production |
0 (nd) |
0 (nd) |
0 (nd) |
|
Non-wood production |
0 (nd) |
0 (nd) |
0 (nd) |
|
Other/unknown wood production |
0 (nd) |
0 (nd) |
0 (nd) |
|
Fodder production |
13 (ns) |
0 (nd) |
1 (ns) |
|
Other purposes |
0 (nd) |
0 (nd) |
0 (nd) |
|
Harvested plantings on arable land ² |
13 (ns) |
68 (22) |
64 (22) |
1 Includes all agricultural crop and dairy industries.² Percentages are based on responses for the most recently harvested stand of trees.
Note: The sample size is insufficient to calculate reliable estimates for the pastoral zone. Figures in parenthesis are relative standard errors (RSE) expressed as percentages of the estimates.
ns = The RSE is not supplied because it exceeds 99 percent (the reliability of this estimate is likely to be low) or because the estimate has been rounded down to zero.
nd = Not determined because the response equate zero.
TABLE 2. Impact of planted trees over ten years of age 1
|
|
Tree blocks |
Alley belts |
Tree belts and corridors |
Widely spaced trees |
|
|
(Percentage) |
|||
|
Reduction in livestock carrying capacity of area occupied by the trees |
37(19) |
31 (55) |
nc |
16(24) |
|
Impact of trees on livestock carrying capacity in area adjacent to the trees |
||||
|
Increase |
38 (16) |
30 (46) |
33 (14) |
39 (60) |
|
No change |
48(14) |
66(20) |
51 (10) |
39 (39) |
|
Decrease |
1 (ns) |
3 (86) |
1 (43) |
3 (nc) |
|
Do not know |
9 (34) |
1 (44) |
11 (34) |
11 (nc) |
|
Not applicable |
3 (56) |
0 |
3 (56) |
|
|
Change in livestock carrying capacity in this adjacent area (if known) |
+2.3 (49) |
+0.5 (66) |
+2.9 (36) |
0 |
|
Impact of trees on crop yields in area adjacent to the trees |
||||
|
Increase |
15 (25) |
21 (61) |
6 (33) |
0 |
|
No change |
29 (29) |
45 (41) |
41 (10) |
0 |
|
Decrease |
9 (47) |
6 (69) |
5 (34) |
0 |
|
Do not know |
13 (33) |
9 (67) |
11 (27) |
0 |
|
Not applicable |
34(27) |
19(66) |
37(10) |
0 |
|
Change in crop yield in this adjacent area (if known) |
+0.2(ns) |
+0.1 (ns) |
-0.2 (ns) |
0 |
|
Impact of trees on rate of soil erosion |
||||
|
Increase |
1 (97) |
3 (ns) |
2(55) |
0 |
|
No change |
45(18) |
69(14) |
61 (7) |
22 (42) |
|
Decrease |
41 (15) |
18 (44) |
25 (19) |
67 (15) |
|
Do not know |
13 (42) |
10 (65) |
13 (26) |
11 (75) |
|
Impact of trees on water table level |
||||
|
Slowing rise in the level |
13 (36) |
19 (65) |
8 (32) |
5 (84) |
|
Stabilizing the level |
4 (89) |
15 (76) |
4 (29) |
0 |
|
Lowering the level |
25 (31) |
6(57) |
12 (30) |
25 (16) |
|
No effect |
29 (26) |
34 (20) |
32 (12) |
40 (41) |
|
Do not know |
29 (26) |
26 (66) |
44 (9) |
30 (55) |
|
Impact of trees on diversity and/or number of wildlife or native plants |
||||
|
Increase |
69 (12) |
71 (5) |
60 (8) |
70 (24) |
|
No change |
24 (34) |
24 (10) |
29 (14) |
18 (88) |
|
Decrease |
0 (ns) |
0 |
0 (ns) |
0 |
|
Do not know |
7 (84) |
5 (58) |
11 (25) |
12 (63) |
1 Includes all agricultural crop and dairy industries: refers to the largest planting of at least 20 trees over ten years of age in each planting regime; percentages are based on responses for farms with these plantings.Note: Figures in parentheses are relative standard errors (RSE) expressed as percentages of the estimates.
nc = Not collected.
ns = The RSE is not supplied because it exceeds 99 percent (the reliability of this estimate is likely to be low or because the estimate has been rounded down to zero.
Experimental observations by Schofield (1991) revealed a close relationship between tree cover and groundwater level. However, as Schofield (1991) warned. "there are many and varied factors which govern realization". Hydrogeological conditions can be such that trees planted on a farm may have no impact on that farm's water table but, instead, affect the height of the water table on another farm. Furthermore, without ongoing monitoring, it is difficult for farmers to assess the actual impact of their planted trees on the water table under their farms.
An important reported impact of mature trees was a reduction in livestock carrying capacity of land occupied by the plantings. On average, rammers reported that the carrying capacity was reduced by 37 percent under tree blocks, 31 percent under alley belts and 16 percent under widely spaced trees. These figures are generally consistent with those in other published studies. For example, Loane (1991) showed that the carrying capacity of land occupied by planted trees is reduced as the age and density of tree plantings increase. Loane cited the example of 20-year-old trees reducing the carrying capacity of the occupied land by 55 percent when the tree density is 100 trees per hectare and by 100 percent when the tree density is 300 trees per hectare. Loane calculated these values on the basis of data for pruned pine trees from Western Australia and New Zealand.
This loss in livestock carrying capacity may be offset by an increase in the carrying capacity of adjacent paddocks sheltered by the trees. On average, the surveyed farmers reported that the carrying capacity of adjacent paddocks increased by 2.3 percent for tree blocks, 0.5 percent for alley belts, 2.9 percent for tree belts and corridors and nil for widely spaced tree plantings (Table 2). Loane (1991) also suggested that shelter effects may increase the livestock carrying capacity and crop yield of adjacent lands. He quoted the results of experimental trials in Victoria and New Zealand, which showed an increase of up to 50 percent in pasture production, implying a potential similar increase in the carrying capacity. Similarly, Thorne (1991) described field experiments conducted on four Victorian farms which showed that the shelter effects from windbreaks reduced the amount of hay required by cattle by 25 percent, increased sheep carrying capacity by 15 percent and enabled lambs to reach market weight earlier.
The reported impact of planted trees on crop yields in adjacent paddocks varied widely (Table 2). However, the average impact was negligible, at an increase of less than 1 percent for each of the planting regimes investigated. Discussing recent experimental trials on the impact of tree plantings on crop yields on adjacent lands, Loane (1991) quoted measured increases of up to 50 percent in oat yields but relatively little increase in wheat yields on the adjacent areas. In contrast, Bicknell (1991) observed no change in oat yields but a net increase of around 20 percent in lupin yields in a region of Western Australia. Similarly, Burke (1991) reported an increase of 20 to 25 percent in wheat yields from a trial at Rutherglen, Victoria.
These results suggest that, in some regions, the actual impact of trees on livestock carrying capacities and crop yields in adjacent paddocks may differ from farmers' perceptions of these impacts. This may mean either that some farmers lack information on the indirect impact of shelter and shade from trees or that the results from the experimental studies cited above are not applicable to the range of environments found across Australia. The apparent lack of information is being addressed by the National Windbreaks Programme. Started in 1993 and funded by the Rural Industries Research and Development Corporation and the Land and Water Resources Research and Development Corporation, the programme is aimed at assessing and informing farmers of the impact of windbreaks on the productivity of crops and pastures across a range of climates and soil types.
Finally, the survey respondents were asked to indicate the impact of their mature plantings on the diversity and number of wildlife or native plants on their farms. The results indicated that 60 to 70 percent of all surveyed farmers perceived the presence of each type of planting to increase the diversity and/or number of wildlife or native plants on their farms.
The national ABARE survey described in this article has yielded considerable information on the extent of planted trees on Australian farms, including the nature, costs and perceived benefits of these plantings. However, the situation is likely to change over time as a result of farmers' own initiatives and the various programmes and policies that promote tree planting and the maintenance of native vegetation on farms It will be useful to monitor those changes using the data obtained in this study as a benchmark.
The process of data collection has also exposed several areas where further research may be warranted. Many of these areas have potential relevance in discussions on the use of trees on farms beyond the Australian situation. Some of these areas include:
· identifying the physical and socioeconomic barriers that constrain farmers in establishing trees on farms for both commercial and noncommercial purposes;· making detailed and targeted regional quantitative assessments of the costs and benefits of growing trees on farms for both commercial and noncommercial purposes (including on-farm trials);
· quantifying the indirect benefits of noncommercial trees on farms;
· quantifying the results of current programmes to promote the planting of trees on farms;
· investigating market prospects for tree products and the marketing challenges faced by farm-based producers;
· investigating farmers' attitudes towards natural forest vegetation on farms, including opportunities for the regeneration and management of these stands, farmers' reasons for clearing them and farmers' plans for cleared forest land;
· investigating farmers' sources of information and the processes that go into shaping their perceptions of the benefits of trees on farmland.
Bicknell, D. 1991. The role of trees in providing shelter and controlling erosion in the dry temperate and semi-arid southern agricultural areas of Western Australia. Paper presented at the Role of Trees in Sustainable Agriculture National Conference, National Agroforestry Working Group, Albury, NSW, Australia, 30 September-3 October.
Bird, P.R., Bicknell, D., Bulman, P.A., Burke, S.J.A., Leys, J.F., Parker, J.N. & Voller, P. 1991. The role of shelter in Australia for protecting soils, plants and livestock. Paper presented at the Role of Trees in Sustainable Agriculture National Conference, National Agroforestry Working Group, Albury, NSW, Australia, 30 September-3 October.
Bulman, P. 1991. Shade, shelter and erosion control - a simplistic model to compare the relative benefits of different farm tree designs for South Australia. Paper presented at the Role of Trees in Sustainable Agriculture National Conference, National Agroforestry Working Group, Albury, NSW, Australia, 30 September-3 October.
Burke, S. 1991. Effect of shelterbelts on crop yields at Rutherglen, Victoria. Paper presented at the Role of Trees in Sustainable Agriculture National Conference, National Agroforestry Working Group, Albury, NSW. Australia, 30 September-3 October.
Loane, B. 1991. Economic evaluation of farm trees: methodology and data for FARMTREE model. Melbourne, Vic., Australia, Joint Agroforestry Management Committee of the Department of Agriculture and Department of Conservation and Environment.
Moore, R. 1991. Producing timber from trees options for farmers in Western Australia. Paper presented at the Role of Trees in Sustainable Agriculture National Conference, National Agroforestry Working Group, Albury, NSW, Australia, 30 September-3 October.
Prinsley, R.T. 1991. Australian agroforestry: setting the scene for future research. Canberra, Rural Industries Research and Development Corporation.
Schofield, N.J. 1991. Tree planting for dryland salinity control in Australia. Paper presented at the Role of Trees in Sustainable Agriculture National Conference, National Agroforestry Working Group, Albury, NSW, Australia, 30 September-3 October.
Stephens, M. & Hansard, A. 1994. An economic assessment of private forestry in northern Tasmania. ABARE Conference Paper 94. Presented at the Biennial Conference of the Australian Forest Growers. Launceston, Tasmania, Australia, 2-5 May.
Thorne, P. 1991. Trees on farms: financial and taxation aspects. Paper presented at the Riverine Outlook Conference: Trees - the essential farm ingredient, Centre for Conservation Farming, Charles Stout University, Wagga Wagga, NSW, Australia, 15 August 1991.
Trapnell, L.N. & Lavery, P.B. 1989. The economics of diversifying from grazing to pines. An analysis for farmers in North eastern Victoria. Joint technical report by the Department of Agriculture and Rural Affairs and the Department of Conservation, Forests and Lands, Melbourne. Vic., Australia.
