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The Bunya in 's Forests

lan R. Smith and Don Butler

Much publicity has been given over the past decade to the discovery of the Wollemi (Wollemia nobilis) north of Sydney and its status as a 'living '. J It is not generally realised that the bunya ( bidwillii), a unique part ofQueensland's forests, has a similar status. The tree is the last surviving species of the section Bunya of the genus Araucaria. This section was more diverse and widespread during the , (Table I), with some species having cone morphology similar to A. bidwillii appearing during the with extending into the northern hemisphere. 2 The species now has a relictual and disjunct distribution in two separate areas in Queensland: in North Queensland it is found at Mt Lewis and at Cannabullen Falls and in South-East Queensland it is found in a zone broadly spread between Gympie and the .' McDonald4 extends this natural distribution in the south through the Conondale Ranges west of the Sunshine Coast to Mt Mee, north-west of Brisbane. There were early reports of a stand of approximately 100 trees in the upper reaches of the Pine River to the south' but these appear to have been logged. The northern and southern populations differ morphologically but, to date, no genetic work has been carried out to explore this difference further.' The individual leaves of the northern form are wider and lack the pungent (sharp) leaf tip of the southern form. NikJes' suggests that while the southern population is secure, the northern is less so and attention should be given to its conservation as a genetic resource.

Constraints to the present natural range of the bunya

A. bidwillii in South-East Queensland occurs across an intriguing area for rainforest geography. This is the 'band' connecting two moist uplands, the coastal Blackall Ranges in the east and Bunya Mountains in the west. This band coincides with the core of a floristically distinct element in South-East Queensland's dry rainforest. The northern boundary of this element marks a division between dry rainforests of a more tropical, monsoonal character north of Gympie, and more

31 tAN R. SMITH AND DON BUTLER subtropical vine forests in the Lockyer Valley to the south.' Numerous species in South-East Queensland's dry rainforests have southern distribution limits near the northern boundary of this floristic region and some southern species have northern limits in the same vicinity. This pattern suggests a band of rainforest refugia, (or areas where rainforest persisted during dryer periods) that may have impeded the southern extension of northern taxa since the beginning of the current inter-glacial.' Most very large seeded species in South-East Queensland's rainforests are restricted to the coastal plain or adjacent ranges but A. bidwillii provides a clear exception to this rule. This band can broadly be characterised as having basaltic soils and moderate altitudes. Perhaps rich volcanic soils were important to its value as a refuge during drier, glacial periods. Webb and Tracey IQ argue that better soil can support 'wetter' forest types than precipitation would predict. A. bidwillii is often found on basaltic soils, but is not confined to them. A. bidwillii can also grow naturally on other igneous substrates and metasediments. Bond" proposed that in soils of lower nutrient status the more conservative (more ancient with naked ) compete effectively with angiosperms (modern flowering plants with enclosed seeds). This observation is clouded by examples in Queensland where many of the occurrences of both A. bidwillii and A. cunninghamii (hoop pine) are on more fertile volcanic soils although some are on older metasediments. 12 In North Queensland the Mt Lewis population is on Mareeba Granites, which produce an unusually fine-grained granitic soil, while the population at Cannabullen Falls National Park and the main channel of Cannabullen Creek follow a narrow basalt flow (Atherton Basalts). Tributaries to the west of the main channel drain extensive areas of Glen Gordon Volcanics rhyolite while those to the east drain extensive areas of Tully Granite Complex. 13 Also influencing the distribution of A. bidwillii are temperature and sufficient I moisture, much of which can be as mist. ' Boland et aJl5 indicate that the main natural distribution of A. bidwillii is within the altitude range of 150-I000m within 160 kms of the coast. These areas have a mean maximum temperature of 28-32°C and a mean minimum of 5-IO"C with up to 30 frosts a year in the southern range. The species occupies various topographical positions from valley floors to ridge tops with an annual rainfall of 900-2000mm, 16 although in common with other emergent araucarians, moisture interception from mist may be an important factor in satisfying water requirements. 17 A study by Hutley et aJl' suggests that cloud and fog may be significant in maintaining rainforest at altitude in South-East Queensland. This is highly likely to be important in the Bunya Mountains and may also be significant in other areas. Although observationally the data regarding mist and frost appear accurate for the distribution of A. bidwillii, this is to be tested by further research. In the Bunya Mountains there is a distinct altitudinal separation of A. bidwillii and A. cunninghamii, with A. bidwillii on the tops grading into A. cunninghamii at decreasing altitudes on both the western and eastern slopes. Although there appears to be a relationship of fertile soils, mist and temperature with the maintenance of A. bidwillii in its native forests, there appears to be no barrier to establishment of healthy trees outside this range. Healthy trees have been

32 THE BUNYA IN QUEENSLAND'S FORESTS planted for ornamental purposes from Tasmania to the tropics in a wide variety of soils and situations. l' One of the most likely reasons for the restricted modern natural distribution of A. bidwillii, apart from climate change is poor dispersal. Cones of A. bidwillii are extremely large and fall intact to the ground before dehiscing. As a result, most seedlings are found close to the parent tree. Since the early Oligocene-Miocene there has been a continual pattern of rainforest contraction and re-expansion which again became more common in the Pliocene2o and declined along with all rainforest in the Pleistocene. Rapid climatic changes associated with Quaternary glaciations caused rapid shrinkage of rainforest,'l although there has once again been expansion of rainforest in the Holocene and recent times. The poor dispersability of the seed of A. bidwillii would prevent it becoming part of any such re-expansion, so a long-term pattern would be contraction in any drier period without significant re-expansion, leading to its present relictual status. The poor dispersability of Antarctic Nothofagus maorei seed is considered responsible for its absence from suitable sites within its range." This is even more likely in the case of A. bidwillii with its even less dispersible seed. Very large, poorly dispersed seeds are a poor combination for colonising sites. A. bidwillii has both of these characteristics. A. bidwillii appears to be an archetypal K selected species. Ecologically, K selection refers to a species which is an excellent site occupier and competitor but a poor colonizer. Animals might be thought of as possible seed vectors for A. bidwillii since it has large, non-toxic, nutritious and relatively soft-shelled seeds. There are, in fact, no animals reported as dispersal agents for the seeds of A. bidwillii although macropods and various species of rats are predators on both the seeds and tubers." Owens" reports that no viable seed could be found on Mt Lewis, North Queensland due to rodent predation. However, Forster" reports A. bidwillii of all size classes on Mt Lewis so some seed obviously survives. Kooymann26 has observed the (Rattus juscipes) caching bunya seed limited distances uphill, thereby allowing continuing ridge-top germination. There have been reports in South America of seeds that were originally dispersed by extinct megafauna now being dispersed by rodents. 27 The possibility of past larger animal vectors should be considered (but is obviously unprovable) in the long history of the species. Man as a vector cannot be ignored. The bunya gatherings were a major feature of Aboriginal society in South-East Queensland." Some anomalous distributions of A. bidwillii may possibly be explained by nuts carried from these gatherings." Man is certainly responsible for the recent spread of the tree, which may lead to naturalised stands in other areas. Naturalisation appears to be occurring in the Auckland Botanic Gardens. Mast seeding (massive seeding at intervals normally greater than annually) is a strategy used by many species to overwhelm seed predators. A. bidwillii has a mast seeding habit with some cones produced every year, but a very heavy crop at three to four year intervals. Folk wisdom is definite on occurrence of this three year cycle. The cause is likely to be connected to a meteorological phenomenon such as ENSO (El Nino-Southern Oscillation). Such a relationship has been found

33 tAN R. SMITH AND DON BUTLER

in South America with another member of the , the monkey puzzle (A. araucana). A. araucana has a similar seeding habit to this species and Sanguinetti et al 30 found a strong relationship between ENSO and seeding of A. araucana in Argentina with wet springs having a strong negative correlation with seeding 16 to 18 months later, perhaps due to interference with wind . One of the most discussed aspects of the ecology of A. bidwil/ii is the unusual crytogeal seed germination in which, following germination, the nutrients from the seed are quickly transferred to form an underground tuber from which the aerial shoot later emerges. 3J The actual emergence of this aerial shoot is then known to occur over several years presumably as a strategy to allow the seedlings to emerge under optimum climatic conditions or, it has been suggested, to avoid fire" This erratic germination has been one of the main problems in the of the species. 33 However, it appears that no study has been done to determine the periodicity of seedling emergence so a small-scale experiment was devised by the author to shed light on this factor. To test germination in A. bidwil/ii, seeds were extracted from two mature cones collected from the same tree, a cultivated specimen at Petrie, a northern suburb of Brisbane (originally the homestead of , the first free European to report the species). One hundred apparently full seeds were selected and planted into 30cm by 12cm plastic tubes filled with sterile potting mix in early February 1999. These were then placed in a shaded area and watered weekly. Four tubes were lost due to being knocked over. The tubes were checked monthly for emergence. The results are presented in Table 2.

Month Emergence 1999 Emergence 2000 Emergence 200I J 8 1 F Seeds Sown 4 1 M 3 A 3 1 M 2 5 J 4 3 J 2 2 A 5 3 S 8 3 0 9 N 12 D 10 TOTAL 55 32

Table 2: Emergence ofAraucaria bidwillii seedlings fonowing seed planting in January 1999-. From Smith (in prep).

34 THE BUNYA IN QUEENSLAND'S FORESTS

It can be seen that final germination was spread over a long period. This spread of shoot emergence presumably maximises the possibility ofat least some successful regeneration in a highly variable climate. It was noted that despite the shaded conditions under which the seedlings were growing and the presence of light at the open edges of the shed in which the study was undertaken there was no phototrophic response and all seedlings maintained a strictly vertical growth pattern.

Bunya community associations

A. bidwillii is very variable with respect to floristic associates in South-East Queensland. Despite occurring in only 36 of the 250 sites surveyed by Butler across the region, sites containing A. bidwillii were placed within 6 of the 15 floristic groups identified in vine forests of the region. Sites with A. bidwillii recorded by Forster et al" receive between approximately 2000 and 800 mm rainfall per annum." They vary structurally from very tall Araucarian Notophyll Vine Forest to Araucarian Microphyll Vine Forests. In drier areas A. bidwillii becomes increasingly confined to near-riparian situations. Within the communities in which southern like the bunya are found there are three broad-scale regeneration strategies: shade intolerant species that rely On infrequent broad scale disturbance to regenerate dense even aged stands which gradually decline as successive generations of predominantly angiosperms regenerate in situ; shade tolerant species that show continuous recruitment and which may dominate a stand structure indefinitely; species which are able to utilise small canopy gaps.36 From observation A. bidwillii generally appears to fit the second category. The species, however, appears to retain the capacity to react to large-scale disturbance as long as sufficient propagules are present. Evidence for this comes from the Blackall Ranges, which was one of the two main strongholds of A. bidwillii along with the Bunya Mountains." The Blackall Ranges were extensively cleared for agriculture from the 1870s onwards. Some steeper slopes were left uncleared, and occasional specimen trees retained. From this a large degree of rainforest in general and A. bidwillii in particular has regenerated. This regrowth of A. bidwillii appears to have increased exponentially over the past 40 years." The boundary between rainforest and other communities is often abrupt resulting from such factors as change of aspect or soil. The abrupt boundary between rainforest containing A. bidwillii and the grassy 'balds' of the Bunya Mountains is particularly interesting. These grassy areas may be relict communities from the last ice-age or from more recent Holocene disturbance, but have almost certainly been maintained by Aboriginal burning." Other aspects of the interactions between A. bidwillii and other members of these communities have been little studied. Fungal interactions can be positive or negative. Mycorrhizal interactions (symbiotic associations between fungi and plant roots) can benefit the host tree. Other Araucaurians such as A. cunninghamii are associated with arbuscular mycorrhiza

35 IAN R. SMITH AND DON BUTLER but no studies have been carried out on A. bidwillii. Other interactions with fungi can be pathological. There has been reponed dieback of A. bidwillii in the Bunya Mountains, with some suggestion of associa· of the native root rot fungus Phellinus noxious which has become a significant iJogen of second rotation plantation grown A. cunninghomii.'" Ganoderma sp. r..', also been found on dead trees. The range of specialised insects, especially weevils, associated with A. bidwillii and other Araucarians warrants a separate study.41 The precise factors which separate the distribution of A. bidwillii and A. cunninghamii have yet to be determined. The wider soil tolerance of A. cunninghomii has already been discussed. In ,;ome areas especially in the Mary Valley and at Jimna, the two species appear to be co-dominant in the community while in the Bunya Mountains there is a grading from A. bidwillii on the summit to A. cunninghamii dominated forest and sclerophyll on an altitudinal basis. Later results are likely to illuminate these variables.

Conclusion

Bunya CA. bidwillii) is an interesting species of high ecological and cultural interest. The current status of its southern population is secure, although the northern population may be considered less so because of its current restricted distribution. The main distribution of A. bidwillii appears confined to particular rainforest types on mainly igneous rocks although it occurs on other substrates. The precise factors constraining its present distribution, however, appear unclear. A. bidwillii appears to be a stable component of these forests, but appears to retain the capacity to react to catastrophic events. Again, however, we have only a superficial knowledge of its population dynamics. Further research is needed to understand the details of its ecology.

Acknowledgments

Thank are given to our supervisors Dr David Lamb, Dr David Doley and Dr Bill McDonald as well as to the numerous people who have helped us in discussions. in the field and in our workplaces. This article is derived from a paper presented at the International Araucariaceae Symposium organised by the International Dendrology Society, Auckland New Zealand 14-17 March 2002. That paper with more extensive data will be published at a later date in the proceedings of that conference.

Notes

J. Woodford. The Wollemi Pine: the Incredible Discovery of a living Fossil from the Age DJ the Dinosaurs, (Melbourne: Text Publishing, 2000). 2 R. S. Hill, ' origin, evolution and diversification in the southern hemisphere' in N. J. Enright and R. S. Hill eds., Ecology ofthe Southern Conifers, (Melbourne: Melbourne University Press, 1995), 10-29. 3 D. 1. Boland et al, Forest Trees of Australia (Melbourne: NelsonlCSIRO, 1984), 42-43.

36 THE BUNYA IN QUEENSLAND'S FORESTS

4 Pers. Comm.. W. J. McDonald, Queensland Herbarium, Brisbane, 1999. 5 Pers. Comm. 1. Bowden. Pine Rivers Shire Council, 2002. 6 Pers. Comm W. 1. McDonald. 7 D. G. Nikles, 'Realized and potential gains from using and conserving genetic resources of Araucaria', in Forestry Problems of the Genus Araucaria (Brazil: FUPEF, 1980), 87-95. 8 D. W. Butler (in prep.), Dispersal, growth form and distribution in subtropical rainforest plants, PhD. Thesis, Department of Botany, University of Queensland, Brisbane. 9 Butler, Dispersal, growth form and distribution. 10 L. J. Webb and 1. G. Tracey, 'Australian rainforests: patterns and change' in A. Keast eel., Ecological Biogeography of Australia, (The Hague: Junk., 1981), 163-297. 11 W. J. Bond, 'The Torroise and the hare: ecology of angiosperm dominance and persistence', Biological Jaurnal of the Linnean Society 36 (1989): 227-249. 12 L. Moloney, An assessment ofthe condition ofBunya Pine Araucaria bidwillii in Bunya Mountains National Park, south·east Queensland, G.Dip. project, UNE, Armidale, 1998; A. Ewart and A. Grenfell, Cainoloic volcanic centres in southeastem Queensland. with special reference to the Main Range, Bunya Mountains and the volcanic centres ofthe nonhem Brisbane coastal region, Pap. Dep. Geo!. Univ. Queensland 11 (3) (1985): 1-57; DME, Gympie Special -1: 100 000 Geological Series, Department of Mines and Energy, Brisbane, 1998; DME Nambour Special ­ 1: 100 000 Geological Series, Department of Mines and Energy, Brisbane, 1998; Geological Survey of Queensland, Gympie·l: 250000 Geological Series. Department of Mines and Energy: Brisbane, 1975; Geological Survey of Queensland, Caboolture·l: 100 000 Geological Series, Department of Mines and Energy, Brisbane, 1979. 13 Pers. Comm. S. Goosem, Wet Tropics Management Authority, Cairns, 2000. 14 1. R. Smith (in prep). Ecology and growth of the bunya pine (Araucaria Bidwillii Hook), PhD. Thesis, Department of Botany, University of Queensland, Brisbane. 15 Boland et al, Forest Trees of Australia. 16 Boland et al, Forest Trees of Australia. 17 N. J. Enright, 'Conifers of tropical Australasia' in Ecology ofthe Southern Conifers, N. J. Enright and R. S. Hill eds.. (Melbourne: Melbourne University Press, 1995), 197-222. 18 L. B. Hutley, D. Doley, D. J. Yates, A. Boonsaner, 'Water balance of an Australian subtropical rainforest at altitude: the ecological and physiological significance of intercepted cloud and fog', Australian Journal of Barany 45 (1997): 311-329. 19 Smith, Ecology and growth of the bunya pine. 20 R. S. Hill, G. J. Jordan and M. K. McPhail, 'History and paleoecology of Australian Nothofagus Forests' in T. T. Yeblen, R. S. Hill and J. Read eds., The Ecalogy and Biogeography ofNothofagus Forests (New Haven: Yale University Press, 1996); M. S. Hopkins, J. Head et al, 'Evidence of a Holocene and continuing recent expansion of lowland rain forest in humid tropical North Queensland', Journal of Biogeography 23 (1996): 737-745; M. K. McPhail, N. F. Alley, E. M. Truswell and I. R. K. Sluiter, 'Early Tertiary vegetation: evidence from spores and pollen' in R. S. Hill eel., History of the Australian Vegetation: Cretaceous to Recent, (Melbourne: Cambridge University Press 1994), 189-261; H. A. Manin, 'Australian tertiary phytogeography: evidence from palynology', in R. S. Hill ed., History of the Australian Vegetation: Cretaceous to Recent, (Melbourne: Cambridge University Press 1994), 104-142. 21 Hill 'Conifer origin, evolution and diversification'. 22 J. Read, 'Ecology of Australian Nothofagus forests' in T. T. Yeblen, R. S. Hill and J. Read eds., The Ecology and Biogeography of Nothofagus Forests, (New Haven: Yale University Press, 1996). 23 Pers. Comm. A. Gardener, retired Forest Manager; Bribie Island, 2000. 24 Owens, internal memo. Dept. of Forestry. Queensland, 1948. 25 Pers. Corom. P. I. Forster, Queensland Herbarium, Brisbane, 2000. 26 Pers. Comm. R. Kooyman. Alstonville. NSW, 2000.

37 IAN R. SMITH AND DON BUTLER

27 P. Forget, 'Seed dispersal of Voucapoua america by cavimorph rodents in French Guiana'. J. Tropical Ecology 6 (1990): 459. 28 H. Sullivan, Aboriginal gatherings in , BA Honours Thesis, Dept. of Prehistory and Anthropology, ANU, Canberra, 1977. 29 J. Huth, The bunya pine: the romantic Araucaria of Queensland, International Araucariaceae Symposium, Auckland, 2002. 30 1. Sanguinetti, L. Maresca et al. Estimation of gross production Dj pinons by the araucaria­ () in the forests ofLanin National Park·Argentin, International Araucariaceae Symposium, Auckland, 2002. 31 G. E. Burrows and R. A. Stockey, 'The developmental anatomy of cryptogeal gennination in Bunya Pine (Araucaria bidwil/ii)' , Int. J. Plant Science 155 5 (1994): 519-537; D. Doley, 'Utilisation of intrinsic water in the gennination of Araucaria bidwillii seeds', Seed Sci. Technol. 18 (1990): 33-42; R. 1. Haines, 'Embryo development and anatomy in Araucaria Juss', Australian Journal of Botany 31 (1983): 125-140; R. J. Haines, 'Seed development in Araucaria Juss', Australian Journal of Botany 31 (1983): 255-267. 32 Burrows and Stockey, 'The developmental anatomy of cryptogeal gennination'. 33 Pers. Comm., Gardner. 34 P. 1. Forster, P. D. Bostock, L. H. Bird and A. R. Bean, Vineforest Plant Atlas for South-East Queensland, (Brisbane: Queensland Herbarinm, 1991). 35 Butler, Dispersal, growth form and distribution. 36 R. L. Ebbett and J. Ogden, 'Comparative seedling growth of five endemic New Zealand podocarp species under different light regimes', New Zealand Journal ofBotany 36 (1998): 189-201; R. L. Ebbett and J. Ogden, 'The Southern conifers - a synthesis' in N. J. Enrigh! and R. S. Hill eds., Ecology of the Southern Conifers, (Melbourne: Melbourne University Press, 1995): 271-287; T. T. Veblen, 'Regeneration patterns in Aracauria araucana forests in Chile', Journal of Biogeography 9 (1982): 11-28. 37 C. C. Petrie, Tom Petrie 's Reminiscences ofEarly Queensland, (St Lucia: University ofQueensland Press, 1904, 1992 reprint): 247-259. 38 Pers. oomm., Gardner. 39 R. J. Fensham and R. J. Fairfax, 'The grassy balds of the Bunya Mountains. south-eastern Queensland. Aoristics and conservation', Cunninghamia 4 (1996): 511-523; L. J. Webb, 'An historical interpretation of the grass balds of the Bunya Mountains, south Queensland', Ecology 45 (1964): 159-162. 40 L. Moloney, An assessment of the condition of Bunya Pine; Pers. Comm. G. Pegg, Queensland Department of Primary Industries, Brisbane, 2002. 41 G. Kuschel, 'Weevils (Curculionidea) in male strobili of Araucariaceae', International Araucariaceae Symposium, Auckland, 2002.

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