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From Pest to Profit (Cont.)

2 The Camphor Laurel Resource

2.1 Methodology

This report on the camphor laurel resource is based largely on distribution mapping and preliminary biomass estimation undertaken by State Forests of New South Wales, Hardwood Plantations Division, Grafton. This source has been supplemented by personal observations and discussions with users. In addition, mapping of the distribution of Cinnamomum camphora has been undertaken by the Department of Land and Water Conservation, Grafton, as part of their regional vegetation mapping program, but results of this study could not be obtained for incorporation into this report. It has not been possible, therefore, to attempt to compare these two independent assessments of species distribution.

The interest by State Forests of New South Wales in camphor laurel distribution is based on the potential for camphor laurel lands to be cleared for timber plantation establishment, and the use of trees cleared from such land for the production of ‘biomass’ for electricity generation (s.1.5). A GIS dataset identifying areas where camphor laurel is either dominant or co-dominant was compiled using the results of aerial photograph interpretation. Vegetation categories used by SFNSW in this study are: scattered trees with dominant camphor laurel (2H), where canopy cover is in the range from 10 to 80% and camphor laurel comprises greater than 50% of canopy cover; clumped trees with dominant camphor laurel (3H), where canopy cover is greater than 80% and camphor laurel comprises greater than 50% of canopy cover; scattered trees with co-dominant camphor laurel (2h), where canopy cover is in the range from 10 to 80% and camphor laurel comprises from 10 to < 50% of canopy cover; clumped trees with co-dominant camphor laurel (3h), where canopy cover is greater than 80% and camphor laurel comprises from 10 to <50% of canopy cover. This exercise was restricted to that area included within twelve 1:25,000 scale map sheets (namely Brays Creek, Nimbin, Larnook, Casino, Burringbar, Huonbrook, Dunoon, Lismore, Pottsville, Brunswick Heads, Byron Bay and Ballina) but excluding land to the east of the Pacific Highway and to the south of the Bruxner Highway, a total area of about 1,934 square kilometres. In addition to determining the distribution of camphor laurel and the area of land covered by these vegetation types, it was sought through this project to provide some estimate of total camphor laurel biomass. To achieve this, randomised branch sampling and importance sampling techniques were first used, from which a function was derived to correlate fresh tree weight with tree diameter at breast height (DBH). From this relationship fresh weights were calculated for trees of known DBH within selected camphor laurel stands, and these were summed to give total stand volume. This methodology is detailed in Carter et al. (in prep.).

In the Department of Land and Water Conservation study, camphor laurel distribution was mapped as part of a program to map the tree cover of the region. Mapping was based on 1991 colour aerial photography at a scale of 1:25,000, mapped directly onto a 1:25,000 topographic base map, and using a minimum polygon area of 4 ha. Tree cover categories relevant to camphor laurel are: camphor laurel forests (D) where tree canopy cover is greater than 30% and where camphor laurel dominates and generally occupies greater than 50% of the forest; mature exotic trees in clumps (V) which are mature camphor laurel trees existing as clumps (more than one tree); and scattered exotic trees (S) which are mature camphor laurel trees existing as individuals in the landscape.

2.2 Distribution and magnitude

The distribution of camphor laurel throughout the Tweed, Brunswick and Richmond catchment areas is best illustrated by the results of the Department of Land and Water Conservation’s regional vegetation mapping program. This information is not available, however, for presentation here. Although the State Forests mapping project covers a smaller part of the range of the species, it does include the most heavily infested areas. Within the mapped area of 193,416 hectares (about 1,934 square kilometres), 78,658 ha (40.7%) contains camphor laurel, of which at least 1,709 ha contains clumped vegetation (>80% canopy cover) with camphor laurel the dominant species (>50% of the canopy). The distribution of camphor laurel within the State Forests study area is depicted in Figure 2.1.

Table 2.1 Areas of land containing C. camphora within the State Forests study area. Figures courtesy of SFNSW, Hardwood Plantations Division, Grafton.

Structure	Canopy cover %	Area (ha)	% of mapped area
Clumped (3H+3h)	>80	1709	0.9
Scattered (2H+2h)	10-80	35177	18.2
Cleared (1H)	<10	29670	15.3
Undifferentiated		12102	6.3
Total area		78658	40.7
Mapped area		193416

Click on the map below for a larger image in a new window

Figure 2.1 Map of State Forests of NSW study area showing distribution of camphor laurel. Courtesy of SFNSW, Hardwood Plantations Division, Grafton.

Figures generated by State Forests for total camphor laurel biomass on four initially-surveyed sites are problematical, but it is believed on the basis of field visits by three of the authors (M. O’Neill, R. O’Neill and B. Stubbs) that 400 tonnes/ha may not be an unrealistic estimate for the above-ground component on the ‘clumped’ sites. These field visits took place on 27 May 1999, with officers of State Forests of NSW, to three camphor laurel stands at Teven, Mullumbimby and Uki, identified by State Forests of NSW as potential plantation sites. Using 200 tonnes/ha as a conservative estimate of standing biomass, this translates to a total biomass in clumped sites of 340,000 tonnes within the mapped area.

Two overseas studies may be of relevance to the estimation of camphor laurel biomass in northeastern New South Wales. In one recent study of a stand of C. camphora growing wild in subtropical Dehra Dun, India, total above-ground biomass was calculated to be 104 t/ha (Singh and Negi 1997). This figure was for dry weight, which, taking into account the reported average moisture loss on drying of 52 percent, translates to a fresh weight of around 217 t/ha. In an earlier study of a 46-year-old pure stand of planted C. camphora in the Tokyo University Forest at Chiba, dry weight of above-ground biomass exclusive of undergrowth was 193-196 t/ha, or around 330- 335 t/ha fresh weight (Satoo 1968). These figures are broadly consistent with the estimate for the Richmond-Tweed sites.

Recommendation 2.1 That a study of the rate of spread of camphor laurel be undertaken. Using the DLWC vegetation map (based on 1991 aerial photography) as a basis, and taking a representative subset of that distribution, determine the distribution in the past (years to be selected according to availability of aerial photography) and at present (by obtaining up-to-date aerial photography, purpose-flown if necessary). Such a project would require a skilled aerial photograph interpreter, as different scales of photography and both colour and monochrome images may be involved. [Department of Land and Water Conservation, Far North Coast County Council, State Forests of NSW, Camphor Laurel Taskforce]

Recommendation 2.2 That research be undertaken into the distribution of biomass (leaves, branches, stem wood, stem bark, +/- roots) within natural stands of C. camphora in the Richmond- Tweed district. [State Forests of NSW, Southern Cross University, Camphor Laurel Taskforce]

2.3 Quality and variety

From the perspective of timber production, the camphor laurel resource is highly variable, ranging from scattered, spreading trees, through moderate to dense cover, often with multi-stemmed habit, to dense stands of relatively straight, single stemmed trees with potential to be cut for sawlogs, or to be managed for future sawlog production. The latter, however, are a very small proportion of the total area of camphor laurel.

There would appear to be at least two different ‘varieties’ of camphor laurel within the Northern Rivers region. These are difficult to distinguish on the basis of external morphological characteristics, but persons with long experience cutting and working the species claim to be able to distinguish varieties on the basis of wood colour (white vs dark), and of wood and leaf aroma (pleasant vs unpleasant/‘medicinal’). There would appear to be a sound basis for this observed difference.

C. camphora has been reported to exist in six chemotypic forms (Hirota and Hiroi 1967, Zhu et al. 1994, Lawrence 1995). The leaf and branch oil can be found to be rich in camphor, linalool, 1,8-cineole, nerolidol, safrole, or borneol. Field workers in China are able to distinguish different chemotypes by their odour, and thereby avoid harvesting foliage which contains mixed chemotypes (Lawrence 1995).

Hirota and Hiroi (1967) report that leaf samples supplied in 1962 from 21 camphor trees growing in Queensland were discriminated on the basis of aroma into those of the eucamphor type (15 trees) and the cineole type (6 trees). More leaves from Australian trees were later supplied and identified as cineole trees (11) and eucamphor trees (19). Results of the recent gas chromatographic analysis of leaf samples from four camphor laurel trees growing in the Lismore area (Friend, 1999) show that three trees are of the camphor type and one is of the cineole type. Gas chromatographic analyses undertaken in August 1999 (Stubbs, unpublished data) of the leaf oil of ten trees growing in the Richmond-Tweed and Hunter districts also reveal the presence of the cineole and camphor chemotypes. Nine samples were of the camphor type, containing on average 68.4 per cent. camphor, and one sample was of the cineole type, containing 52.2 per cent. cineole with less than 1 per cent. camphor. The foregoing all demonstrate the existence in Australia of two of the recognised chemotypes.

To highlight the natural variability in the physical characteristics of C. camphorait is mentioned that Geerts (1875) distinguished fifteen varieties of this species on the basis of wood colour and quality. How much of this variability is present within Australian camphor is unknown. Together with the above-mentioned uncertainty about chemical variation, this points to the need for further study of the properties of the Australian populations of C. camphora.

Recommendation 2.3 That a comprehensive study be made of the physical and mechanical properties of timber from local camphor laurel trees, with special attention to the existence of different ‘varieties’, and to variations in timber properties according to site conditions. The work of Shukla et al. (1994) could form a partial basis for such a study. [Northern Rivers Regional Development Board, State Forests of NSW, Southern Cross University, Camphor Laurel Taskforce]

Recommendation 2.4 That a study be undertaken of the micromorphological characteristics of the leaves of the two chemotypes of C. camphora within the Richmond-Tweed region, distinguished on the basis of oil composition, with the aim of developing an objective field technique for the rapid discrimination of these varieties. The work of Singh, Baruah and Nath (1995) could form a basis for such a study. [Northern Rivers Regional Development Board, State Forests of NSW, Southern Cross University, Camphor Laurel Taskforce]

2.4 Implications of resource characteristics for camphor utilisation

The camphor laurel resource of the Northern Rivers region is highly fragmented and widely dispersed. It exists in a wide variety of geographical situations, is in multiple, public and private ownership across a range of land tenures, is subject to varying regulatory regimes (e.g. different local government areas), is structurally variable, and comprises at least two chemical forms. These features of the resource, regardless of its recent declaration as a noxious weed across much of its range (s.1.3), have important implications for its future utilisation.

2.4.1 Location
Whilst it is common throughout most parts of the northern rivers and extends as far south as Bellingen and Kempsey, the bulk of the camphor laurel resource (whether it be for biomass production or sawmilling) is confined to the more fertile soils extending from the Lismore area east towards Ballina and north into the Tweed. It is this region that holds most commercial interest because of the higher concentration of the resource.

2.4.2 Terrain
The terrain on which camphor laurel has become established varies from drainage flats and undulating valleys to moderately steep to very steep slopes. The steeper areas and riparian corridors present particular challenges for clearing or harvesting the resource, not only from an economic viewpoint but also in respect to compliance with land use legislation (see s.3.4.1).

2.4.3 Stand density and tree size
Stand density varies from single paddock trees to closed forests. It is the closed forests that represent the greatest potential for both biomass and sawlog production because of their wide range of tree sizes; the less dense stands and paddock trees, by virtue of their growth habit, yield larger stems suitable for slab production. It is estimated that sawlogs suitable for the production of quality sawn boards make up less than 10% of the resource. The remainder is suitable for biomass for fuel, for oil production, and, probably on a relatively small scale, for the supply of specialised timber sections for a variety of uses.

2.4.4 Growth habit
Multi-stemming is a common feature of camphor laurel and can occur in both forest and opengrown trees. This growth habit reduces the potential of the resource to produce stems suitable for sawn conversion and also raises safety issues with the falling and servicing of trees. Single stem trees are more common to the closed-forest situation and in the best developed stands provide opportunities for sawlog recovery in association with clearing or harvesting that in the main will produce biomass.

2.4.5 Foreign objects
The existence within some camphor laurel trees of debris (glass, crockery, metal objects), nails, fencing wire and other foreign objects potentially damaging to saws introduces an element of risk into their utilisation. This can be a problem particularly with old, multi-stemmed paddock trees (debris) and with trees growing on roadsides (nails and wire).

2.4.6 Chemotypes
The existence of at least two chemical varieties of Cinnamomum camphora within the Richmond- Tweed district clearly has implications for the production of camphor oil. These are discussed in more detail below (s.4.4). It is possible, too, that timber properties may vary between types. Mechanical properties may remain constant, but noted variation in colour and aroma may make one type favoured over another for some uses. Timber properties are also considered in more detail below (s.4.3.3).

2.4.7 Land tenure
The fact that the camphor laurel resource is in multiple ownership across a wide range of land tenures is a challenge for those wishing to exploit it commercially. This fact introduces significant inefficiencies into the process of obtaining access to the resource.

2.5 Potential timber volumes

Very little quantitative data on the camphor laurel resource is available. As described above, State Forests of NSW have undertaken a mapping and field verification project over an area of 193,416 hectares of the Richmond-Tweed district where the heaviest infestations of camphor laurel occur. Of this it was determined that 78,658 hectares carried camphor laurel in varying densities. Some of these areas were inspected by the study team as part of this project. To date there is no reliable area information on the remainder of the camphor resource in the Northern Rivers region. Nevertheless, it is possible from State Forests mapping and inventory data to estimate the biomass volume in the clumped or forested stands, as there is general agreement that it is conservatively in the order of 200 tonnes per hectare, which figure is adopted here for the purposes of calculation. An estimate of the per hectare volumes in scattered and cleared areas and indeed for the unmapped resource is, however, a far less precise exercise. Based on the SFNSW area statements for each of the structure categories mapped, an estimate of the volume of the resource is tabulated below (Table 2.2), including an indicative estimate of the resource outside the SFNSW study area.

Table 2.2 Estimated magnitude of camphor laurel resource.

Stand structure	Area* (ha)	Est. biomass (t/ha)	Est total biomass (t)	Est. qty suitable for sawn conversion (t)	Est. qty suitable for sawn conversion (m3)
clumped	1,709	200	341,800	34,180	29,100
scattered	35,177	20	703,540	14,100	12,000
cleared	29,670	5	148,350	7,400	6,300
undifferent.	12,102	20	242,040	12,100	10,300
unmapped	50,000	20	1,000,000	50,000	42,550
TOTAL	128,658	-	2,435,730	117,780	100,250

Note: Weights are for green timber. Estimates of the quantity suitable for sawn conversion are based on 10 per cent. recovery from clumped stands, 2 per cent. recovery from scattered stands, and 5 per cent. from cleared sites, undifferentiated areas, and unmapped areas. The volume suitable for sawn conversion includes products such as slabs, boards, whorls, turning blocks and turning circles. For the purposes of later costings, the sawn component has been converted to cubic metres (m3) in this table, and throughout the report. Conversion is based on a green wood density of 1.175 t/m3. Area data (*) for clumped, scattered, cleared and undifferentiated categories courtesy of SFNSW, Hardwood Plantations Division, Grafton (see also Table 2.1).

It must be re-emphasised that these estimates are based on insufficient information to make them highly reliable; they should therefore be regarded as tentative only. Additionally, a number of factors will contribute to a significant reduction in this estimated volume of total biomass and trees suitable for sawn conversion, including:

(i) State Forests of NSW are not considering the whole area for plantation establishment;

(ii) access to all areas will not be feasible, particularly where sawlog volumes are marginal;

(iii) some landowners will not be interested in either clearing or logging;

(iv) Council restrictions may apply in some areas; and

(v) legislation relating to threatened species and to clearing may limit access to some areas.

The declaration of camphor laurel as a noxious weed, however, will encourage the removal of the species across part of its range, probably offsetting the above factors to some extent, although it is too early to know precisely how this effect will operate.

Allowing for these factors, it is estimated that the total available biomass is in the order of 1,200,000-1,500,000 tonnes, and that the available sawlog volume is 50,000-60,000m3. State Forests of NSW have commenced a more intensive inventory project and will be conducting clearing trials on a limited basis to determine a more accurate estimate of total biomass. The information from both these projects should be available later this year, and the above estimates should be reviewed in the light thereof.

Recommendation 2.5 That information from later inventories and biomass trials by State Forests of NSW and the Department of Land and Water Conservation be used to review the available volume estimates made here. [State Forests of NSW, Department of Land and Water Conservation, Camphor Laurel Taskforce]

Besides the data for the area of camphor laurel in several stand structure categories and the derived biomass figures presented in table 2.2, the rate of growth of the species is an aspect which must be taken into account in the overall planning for clearing and replanting. For the Northern Rivers region there seem to be no records, however, of the measurement of either individual stems or of stands. To allow for preliminary calculations, however, some estimates of stand growth have been made based on experience with other forest types. It is speculated that the annual growth increment for clumped sites would be at least in the order of 5m3/ha/annum, and of scattered sites, together with undifferentiated stands and unmapped areas, in the order of 0.5m3/ha/annum. Over the total areas for these resource categories given in table 2.2 (cleared sites have been ignored), this gives a conservative annual rate of growth of camphor laurel biomass in excess of 50,000 tonnes, of which some unknown proportion will represent millable timber.

Recommendation 2.6 That growth modelling of camphor laurel stands be undertaken in order to predict annual rates of biomass accumulation, and of timber growth. [State Forests of NSW, Southern Cross University, Camphor Laurel Taskforce]

There would appear to be the possibility of improving on the above estimates of stand growth by carrying out an investigation of whether the species produces annual growth rings. If it is possible to identify sample trees of known age, preferably across a range of sizes, then this question can be answered. If the rings are annual, then stem analysis can provide the periodic volume increment of individual stems. This can then be extrapolated to a stand. If the rings are not annual, then it may still be possible to determine growth in a less precise manner by consideration of ‘false’ and ‘incomplete’ rings.

Recommendation 2.7 That a study be made of individual trees of known age to determine whether growth rings are annual, and whether stem analysis can provide estimates of periodic volume increment. If the rings are annual, then the study should be extended to provide estimates of periodic volume increments in stands.
[Southern Cross University, State Forests of NSW, Camphor Laurel Taskforce]

2.6 References

Carter, P., Whittall, J. and Lamb, K., in prep. ‘Random branch sampling for direct estimation of biomass weight of Cinnamomum camphora on the north coast of NSW.’

Friend, J., 1999. ‘More than one camphor?’, Big Scrub Landcare 3(8), 15-16.

Geerts, Dr, 1875. ‘Preliminary catalogue of the Japanese kinds of wood, with the names of the timber trees from which they are obtained’. Transactions of the Asiatic Society of Japan 4, 1- 26.

Hirota, N. and Hiroi, M., 1967. ‘The later studies on the camphor tree, on the leaf oil of each practical form and its utilisation’, Perfumery and Essential Oil Record 58, 364-367.

Lawrence, B. M., 1995. ‘Progress in essential oils’, Perfumer and Flavorist 20, 29-41.

Satoo, T., 1968. ‘Primary production and distribution of produced dry matter in a plantation of Cinnamomum camphora’, Bulletin of the Tokyo University Forests no. 64, 241-275.

Shukla, N. K., Guru, R. D., Singh, K. R., Khanduri, A. K. and Lal, M., 1994. ‘A note on physical and mechanical properties of some natural grown and plantation timbers’, Journal of the Indian Academy of Wood Science 25(1-2), 67-77.

Singh, J., Barua, K. N. and Nath, S. C., 1995. ‘Comparative micromorphological studies of two chemotypes of Cinnamomum camphora (L.) J. Presl’, Acta Botanica Indica 23, 127-128.

Singh, R. and Negi, J. D. S., 1997. ‘Biomass prediction and distribution of organic matter in a natural Cinnamomum camphora stand’, Indian Forester 123(12), 1161-1170.

Zhu, L., Ding, D. and Lawrence, B. M., 1994. ‘The Cinnamomum species in China: resources for the present and future’, Perfumer and Flavorist 19, 17-22.

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