Monthly archives of “June 2014

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Cladophlebis – New Zealand’s Mesozoic Weed

The fern Cladophlebis is probably the single-most common plant fossil in the New Zealand Jurassic. It’s present in virtually every plant fossil site of that age, so much so that Mildenhall (1974) referred to it as ‘Mesozoic weed’. When New Zealanders talk about ‘fern rock’, it’s a good bet they’re referring to a deposit of fossil Cladophlebis. It’s abundance and ubiquity suggest we should be making the most of it – so just what is this Cladophlebis?

A typical slab of 'fern rock' from the Catlins. The preserved length of the Cladophlebis fossil frond at right is about 100 mm.

A typical slab of ‘fossil fern rock’ from the Catlins, New Zealand. The preserved length of the frond at right is about 100 mm.

Detail of a fossil Cladophlebis patagonica from New Zealand. As usual, vein details are somewhat vague, but enough to show that they only fork once. Pinnule lengths about 15 mm.

Detail of a Cladophlebis patagonica. As usual, vein details are somewhat vague, but enough to show that they only fork once. Pinnule lengths about 15 mm.

Cladophlebis was first defined by Brongniart in 1849. He wrote (my translation from the French):

This genus, which corresponds to the section of Pecopteris neuropteroides, (?In) the history of fossil Vegetables, still seems to me, after a more extended study, a natural and rather easy group to be characterized and able to be raised to the rank of genus; it actually forms the transition of Pecopteris to Neuropteris, it differs from the later by the pinnules which are not isolated from the rachis, but that are close-fitting to it though often free between them, and even partly contracted, and display a short rounded ear at their base; which is seen especially in Pecopteris nestleriana and P. defrancii. The veins are less fine, more separated, and are less obliquely branch from the median vein which, although fades towards end, persists in a distinct way up to the apex. These plants differ from other genera formed at the expense of Pecopteris, and particularly from the true Pecopteris, by their bent/hooked secondary veins and dichotomies. Cladophlebis pteroides has so much affinity with the true Neuropteris, by its absolute characters, that perhaps we should place it in this genus, though it does not have ‘respect’ of it. Several species of this genus belong to the Mesozoic, but most of them come from coal fields.

Cladophlebis therefore, is used for fern fronds with pinnules that are attached to the rachis, and have a median vein that runs to the apex of the pinnule, and veins from that are curved and dichotomise. Other characters, such as the vein thickness, separation, and branching angle, are more subjective and relative to the genera Neuropteris and Pecopteris. It’s not much to go on, but the genus has persevered – and quite a number of species have been described for it.

Cladophlebis was gradually recognised as a ‘form genus’. That is, it was applied to a morphology where the higher relationships – i.e. the family, were not known. However, the family relationships for at least some Cladophlebis did become clear, or at least suspected. For example, some fronds have been found with the fertile sori (which are a good clue to a fern’s family) and sometimes they have been found with petrified stems. In several instances these have indicated the family was the Osmundaceae, although Dicksoniaceae and Schizaeaceae are also known to have had Cladophlebis foliage.

But, and here things get even more complicated, a Cladophlebis frond with attached sori can be identified to a family, so it can be placed into an ‘organ genus’. For most Cladophlebis-with-fronds, this is Todites (Harris 1937). The stems are treated separately and receive such names as ‘Osmundites‘.  More recently, both ‘form genus’ and ‘organ genus’ have been dropped by the International Botanical Code – in favour of ‘morphogenus’ (see Bateman and Hilton 2009 for a detailed discussion of this topic). Whatever word is used to describe it, Cladophlebis remains a term to describe a fairly broad shape. Although one frequently comes across comments that Cladophlebis became extinct at the end of the Mesozoic, this is not true. The morphology covered by Cladophlebis exists today. It’s simply that by convention paleobotanists usually refrain from using ‘form genera’ in the Cenozoic and tend to place fronds in extant genera.

There aren’t too many characters that can be used to split Cladophlebis into species-sized bites. There is the size and shape of the pinnules, whether the margin is toothed or smooth, and the forking behaviour of the veins (i.e. forking once, twice, at the mid vein or distant from it, and so-on). Following the work of the paleobotanists who pioneered study of New Zealand’s fossil plants (Arber 1917 and Edwards 1934) there appeared to be at least five species of Cladophlebis in the New Zealand Jurassic. These were: Cladophlebis australis, C. sp. cf. C. albertsi, C. antarctica, C. denticulata and C. cf. reversa. Arber (1917, 31) regarded C. australis as the “most abundant of all species, without exception” in the New Zealand Jurassic.

However, a few years later, Frenguelli (1947) decided that the New Zealand Jurassic ‘Cladophlebis australis‘ actually belonged in a new species. He named this Cladophlebis patagonica, and it could be recognised by having lateral veins that mostly bifurcated only  once, whereas in the real C. australis double-bifurcation was prominent. Herbst (1971) formalised the description of C. patagonica as part of a review of the Argentinian Cladophlebis. Retallack (1983), a specialist in the Triassic, noted that based on the double-forking definition, C. australis is a species basically restricted to the Triassic. In my work on the Jurassic of the Catlins coast, I’ve only seen rare instances of double-bifurcation (despite being common fossils, details of the venation can be frustratingly vague). These are probably just a morphological extreme in a population of Cladophlebis patagonica. However, in the North Island, Thorn (2001, fig. 6d) illustrates a Cladophlebis pinnule with several instances of double (as well as ? ‘one and a half’) bifurcation, compares with with C. australis.

Cladophlebis antarctica and C. denticulata seem to be good identifications in the New Zealand Jurassic. They both have non entire pinnule margins (variously described as toothed, crenate,serrate, serrulate) and can be distinguished on pinnule form, angle and vein spacing (Gee 1989). The remaining species are probably bad ideas – based on poor specimens that little can be done with. Thus the total Cladophlebis in the New Zealand Jurassic appears to have been just three, though careful analysis of pinnule size and shape may well tease out some more. This total compares with the six that Herbst (1971) concluded with for the Patagonian Early Jurassic, but which decreased also to three in the Middle and Late Jurassic.

Based on our Cladophlebis species New Zealand in the Jurassic had links with Patagonia. Two of the species, C. antarctica and C. denticulata, are also present in the Cretaceous of Hope Bay, Antarctica (Gee 1989). It’s highly likely that New Zealand shared Cladophlebis species with eastern Australia, although at the moment this remains somewhat unclear. Just like New Zealand, earlier workers in Australia tended to lump their Jurassic Cladophlebis into C. australis. More recent workers have been more cagey – McLoughlin et al. (1995) declined to put their Early Cretaceous Cladophlebis into any species. They noted that variation over individual fronds was so much that they could be compared with several species. They did note their material was similar to what has been described as Cladophlebis australis – but also noted that the veins in their material could dichotomise once or twice.  It may yet be that Cladophlebis patagonica is applicable to some Australian fossils.

In the Catlins of New Zealand, petrified stems are commonly found closely associated with Cladophlebis fronds. Most of these were probably the stems of C. patagonica and indicate it was a modest-sized tree-fern. There are more than two species of fossil stem – in agreement with more than one species of Cladophlebis. However, the stems are another part of a complicated story. ‘Mesozoic weed’ would avoid a lot of head-scratching….

References

Bateman, R. M. & Hilton, J. 2009: Palaeobotanical systematics for the phylogenetic age: applying organspecies, form-species and phylogenetic species concepts in a framework of reconstructed fossil and extant whole-plants. Taxon 58: 1254-1280.

Brongniart, A.T. 1849. p. 74, In d’Orbigny, A. C. V. D. ‘Dictionairre Universel d’Histoire Naturelle’ Vol 13. Langlois et Leclerq, Paris.

Edwards, W.N., 1934:  Jurassic plants from New Zealand. Annals and Magazine of Natural History 10, 81-109.

Frenguelli, J., 1947: El género Cladophlebis y sus representantes en la Argentina. Anales del Museo de La Plata (Nueva Serie) 2, 1-74.

Harris, T. M. 1937: The fossil flora of Scoresby Sound, East Greenland, part 5. Meddeleeser om Gronland 112(2): 1-114.

Herbst, R. 1971: Palaeophytologia Kurtziana III. 7. Revision de las especies Argentinas del genero Cladophlebis. Ameghiniana 8: 265-281.

Mildenhall, D. C. 1974: The record of the rocks. New Zealand’s Nature Heritage 1: 43-47.

Thorn, V. 2001: Vegetation communities of a high paleolatitude Middle Jurassic forest in New Zealand. Palaeogeography, Palaeoclimatology, Palaeoecology 168: 273-289.

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Is New Zealand in the Anthropocene?

Has New Zealand recently entered an entirely new period of time?

You may have caught up with the proposal that the world is now in a new era of time – the Anthropocene. Geologists have previously told us that we lived in the period called the Holocene. This is generally agreed to have begun 11,700 years ago – as the world rapidly warmed out of the last glacial period. When I first heard the term ‘Anthropocene’ I assumed it was more a smart marketing ploy to draw attention to a lot of the world’s serious issues. Actually, it is partially that, but that would be to also miss the point.

Geological divisions of time are based on recognising periods of geologically sudden, profound, and regionally recognisable change in the sedimentary record. These become codified as the boundaries between time periods. Several of the major periods in Earth history are recognised primarily through pervasive extinction events. The Cretaceous-Cenozoic boundary, when the dinosaurs became extinct, is one, extreme, example. But less pronounced change can also be the basis of period boundaries and also, looking beyond fossils, boundaries may also be recognised on other criteria – for example chemistry or climate.

Recognising whether we have recently entered a new time period requires that we take a geological perspective. If we were geologists, say, 100 million years from now, and set to defining a geological time scale – would we recognise an important boundary for about now? For the people responsible for ‘managing’ the current international scale, (Stratigraphy Commission of the Geological Society of London) the answer is definitely “Yes”. My question here is, if geologists 100 million years ago were only looking at New Zealand – would they come to the same conclusion?

When they study fossils, future geologists will find a remarkable extinction event correlating with the appearance of humans in New Zealand. Humans arrived in New Zealand about AD 1200-1400 (McGlone and Wilmshurst, 1999). These were Polynesians, and were followed 600 years or less later by Europeans. This 600 years, which is of so much importance to historians and politicians, is utterly trivial on geological time scales. Six hundred years would be well below the level of resolution of all but the slowest and most continuous sedimentary successions. For the geologists 100 million years in the future, it would be essentially instantaneous.

Over that ‘boundary’ future paleontologists would note that New Zealand lost 40-50% of its birds (Holdaway 1989). This is the proportion of birds that have become extinct in New Zealand since humans arrived – it doesn’t include those species that have had their range reduced so much that realistically, they will no longer contribute to a fossil record, and may yet go completely extinct. A similar amount of extinction  has hit the frog fauna (Holdaway 1989), while the figures are still unclear for other groups such as lizards and insects. At the same time, there has been a massive influx of new species from beyond New Zealand, including entirely new groups of land verterbrates, and of course, humans themselves.

One of the surest signs of humans has been the dramatic increase in charcoal content of sediments from almost nil. Palynologists often study the charcoal content of peat swamps along with the enclosed pollen. In New Zealand this kind of study shows the increase of charcoal starting around 800 years ago McWethy et al. 2009, 2010). A hundred million years from now, what peat remains will be coal. The typical one or two meter column of peat that palynologists study today might then be only 30 cm or so thick. Furthermore, what was a nice sampling interval in the peat (to get enough resolution to understand the process) – say two centimetres, will now be compacted to just millimetres, and very difficult to study. Once again, on a geological scale, the appearance of abundant charcoal in New Zealand will appear practically instantaneous. It will correlate with the appearance of diverse range of pollen from introduced plants.

Beyond their actual artifacts, humans are making other changes that will be apparent in the future geological record. Deforestation (some of it the result of the afore-mentioned burning) have significantly increased erosion rates (McSaveny and Whitehouse 1989). The corollary of this is increased sedimentation somewhere else. River, lakes, estuaries are silting up. After a long period of fairly stable Holocene sea level, sea level is on the rise due to global warming. At around 3 mm per year, it seems so slow. But at 3 m in 10,000 years, or 30 m in 100, 000 years, this will ultimately be recognisable as a transgression – with a  ‘sequence boundary’ at its base. A change in the character of New Zealand’s sedimentary record will be apparent.

The tons of artificial fertilisers that are now applied to New Zealand farms, along with various metals from industrial pollution, will be visible in the future geochemical record. More ominously, acidification of the oceans will lead to the dissolving of calcium carbonate at increasingly shallower depths. What would have once formed a deep water carbonate sediment may be visible to future geologists as a much thinner bed of clay-rich sediment.

The list of rapid change could go on and on – it certainly seems to me that New Zealand has joined the Anthropocene.

References

Holdaway, R. N. 1989: New Zealand’s pre-human avifauna and its vulnerability. New Zealand Journal of Ecology 12: 11-25.

McGlone, M. S. & Wilmshurst, J. M. 1999: Dating initial Maori environmental impact in New Zealand. Quaternary International 59: 5-16.

McSaveney, M. J. & Whitehouse, I. E. 1989: Anthropic erosion of mountainland in Canterbury. New Zealand Journal of Ecology 12: 151-163.

McWethy, D. B., Whitlock, C., Wilmshurst, J. M., McGlone, M. S. & Li, X. 2009: Rapid deforestation of South Island, New Zealand, by early Polynesian fires. The Holocene 19: 883-897.

McWethy DB, Whitlock C, Wilmshurst JM, McGlone MS, Fromont M, Li X, Dieffenbacher-Krall A, Hobbs WO, Fritz SC, Cook ER 2010. Rapid landscape transformation in South Island, New Zealand, following initial Polynesian settlement. Proceedings of the National Academy of Sciences of the United States of America 107: 21343-21348

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Is New Zealand in the Anthropocene?

Has New Zealand recently entered an entirely new period of time?

You may have caught up with the proposal that the world is now in a new era of time – the Anthropocene. Geologists have previously told us that we lived in the period called the Holocene. This is generally agreed to have begun 11,700 years ago – as the world rapidly warmed out of the last glacial period. When I first heard the term ‘Anthropocene’ I assumed it was more a smart marketing ploy to draw attention to a lot of the world’s serious issues. Actually, it is partially that, but that would be to also miss the point.

Geological divisions of time are based on recognising periods of geologically sudden, profound, and regionally recognisable change in the sedimentary record. These become codified as the boundaries between time periods. Several of the major periods in Earth history are recognised primarily through pervasive extinction events. The Cretaceous-Cenozoic boundary, when the dinosaurs became extinct, is one, extreme, example. But less pronounced change can also be the basis of period boundaries and also, looking beyond fossils, boundaries may also be recognised on other criteria – for example chemistry or climate.

Recognising whether we have recently entered a new time period requires that we take a geological perspective. If we were geologists, say, 100 million years from now, and set to defining a geological time scale – would we recognise an important boundary for about now? For the people responsible for ‘managing’ the current international scale, (Stratigraphy Commission of the Geological Society of London) the answer is definitely “Yes”. My question here is, if geologists 100 million years ago were only looking at New Zealand – would they come to the same conclusion?

When they study fossils, future geologists will find a remarkable extinction event correlating with the appearance of humans in New Zealand. Humans arrived in New Zealand about AD 1200-1400 (McGlone and Wilmshurst, 1999). These were Polynesians, and were followed 600 years or less later by Europeans. This 600 years, which is of so much importance to historians and politicians, is utterly trivial on geological time scales. Six hundred years would be well below the level of resolution of all but the slowest and most continuous sedimentary successions. For the geologists 100 million years in the future, it would be essentially instantaneous.

Over that ‘boundary’ future paleontologists would note that New Zealand lost 40-50% of its birds (Holdaway 1989). This is the proportion of birds that have become extinct in New Zealand since humans arrived – it doesn’t include those species that have had their range reduced so much that realistically, they will no longer contribute to a fossil record, and may yet go completely extinct. A similar amount of extinction  has hit the frog fauna (Holdaway 1989), while the figures are still unclear for other groups such as lizards and insects. At the same time, there has been a massive influx of new species from beyond New Zealand, including entirely new groups of land verterbrates, and of course, humans themselves.

One of the surest signs of humans has been the dramatic increase in charcoal content of sediments from almost nil. Palynologists often study the charcoal content of peat swamps along with the enclosed pollen. In New Zealand this kind of study shows the increase of charcoal starting around 800 years ago McWethy et al. 2009, 2010). A hundred million years from now, what peat remains will be coal. The typical one or two meter column of peat that palynologists study today might then be only 30 cm or so thick. Furthermore, what was a nice sampling interval in the peat (to get enough resolution to understand the process) – say two centimetres, will now be compacted to just millimetres, and very difficult to study. Once again, on a geological scale, the appearance of abundant charcoal in New Zealand will appear practically instantaneous. It will correlate with the appearance of diverse range of pollen from introduced plants.

Beyond their actual artifacts, humans are making other changes that will be apparent in the future geological record. Deforestation (some of it the result of the afore-mentioned burning) have significantly increased erosion rates (McSaveny and Whitehouse 1989). The corollary of this is increased sedimentation somewhere else. River, lakes, estuaries are silting up. After a long period of fairly stable Holocene sea level, sea level is on the rise due to global warming. At around 3 mm per year, it seems so slow. But at 3 m in 10,000 years, or 30 m in 100, 000 years, this will ultimately be recognisable as a transgression – with a  ‘sequence boundary’ at its base. A change in the character of New Zealand’s sedimentary record will be apparent.

The tons of artificial fertilisers that are now applied to New Zealand farms, along with various metals from industrial pollution, will be visible in the future geochemical record. More ominously, acidification of the oceans will lead to the dissolving of calcium carbonate at increasingly shallower depths. What would have once formed a deep water carbonate sediment may be visible to future geologists as a much thinner bed of clay-rich sediment.

The list of rapid change could go on and on – it certainly seems to me that New Zealand has joined the Anthropocene.

References

Holdaway, R. N. 1989: New Zealand’s pre-human avifauna and its vulnerability. New Zealand Journal of Ecology 12: 11-25.

McGlone, M. S. & Wilmshurst, J. M. 1999: Dating initial Maori environmental impact in New Zealand. Quaternary International 59: 5-16.

McSaveney, M. J. & Whitehouse, I. E. 1989: Anthropic erosion of mountainland in Canterbury. New Zealand Journal of Ecology 12: 151-163.

McWethy, D. B., Whitlock, C., Wilmshurst, J. M., McGlone, M. S. & Li, X. 2009: Rapid deforestation of South Island, New Zealand, by early Polynesian fires. The Holocene 19: 883-897.

McWethy DB, Whitlock C, Wilmshurst JM, McGlone MS, Fromont M, Li X, Dieffenbacher-Krall A, Hobbs WO, Fritz SC, Cook ER 2010. Rapid landscape transformation in South Island, New Zealand, following initial Polynesian settlement. Proceedings of the National Academy of Sciences of the United States of America 107: 21343-21348

Matai (Prumnopitys taxifolia) foliage
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Matai- vanquished giant of New Zealand’s dry forests?

I’ve long found New Zealand’s black pine, the matai (Prumnopitys taxifolia) to be a special tree. From a dishevelled juvenile, It can grow into one of our tallest and oldest plants. Its foliage, unlike the delicate feathers of its smaller relative the miro, has a more scruffy appearance. It is by no means rare, but its distribution is scattered – and this may be instructive.

J.T. Holloway found matai to be very instructive, and he focussed 19 pages of his hypothesis on climate-change and forests in the South Island around it (Holloway 1954). He pointed out that although matai were widely-distributed, forests in the drier, eastern side of the South Island in which matai was prominent tended to be “discontinuous small pockets of forest surrounded by tussock grasslands, manuka scrublands or, more rarely, by beech forests of varying type.” He could find no evidence that current climate or soil was behind this although in none of the “pocket handkerchief” sized fragments did matai appear to be regenerating. Holloway argued – with basically circumstantial evidence – that these forests with matai had once been more continuous. There had then been a climate change coinciding with early Polynesian times. This simultaneously facilitated the burning of these drier forests (that also included kahikatea/Dacrycarpus and totara/Podocarpus) and hampered their regeneration.

Since then, there has been further evidence uncovered for more widespread matai. In 1963 Cox and Mead published their research into the complex of buried river deposits and soils, from near Christchurch. Matai remains were prominent as charcoal and seeds. Burrows (1980) and Burrows et al. (1981, 1984) found matai remains associated with moas at The Deans and Pyramid Valley in Canterbury, and Scaifes Lagoon on the edge of Lake Wanaka. Scaifes Lagoon is just 5 km to the east of the two ‘most central’ living matai that I am aware of. One is up in a rock fall above Diamond Lake, while the other is on the edge of the West Wanaka road, near the lake. I also recall seeing matai seeds in the swamp peat about 2 km to the east of Scaifes when I was about 10. A further occurrence is a small fragment of cuticle figured by Wood et al. (2012) as ‘podocarp’, from the edge off Lake Wakatipu, which is matai.

The matai above Diamond Lake, near Wanaka. The matai tree is right on the shadow line, towards the left.

The matai above Diamond Lake. It’s right on the shadow line, towards the left.

Close up of the trunk of the Diamond Lake matai tree

Close up of the trunk of the Diamond Lake matai.

Cox and Mead’s work may appear to only extend the original range of matai slightly to the west of where it now occurs. However, it puts them on the drier plains rather than the uplands of Banks Peninsula. With this evidence it is easier to imagine matais on the plains further to the south, and perhaps even in Central Otago.

Map of Matai tree records in the South Island, New Zealand.

Matai records in the South Island, New Zealand. Red = current records from the GBIF (I note this doesnt include some sites such as Geraldine), blue = charcoal in Cox and Mead (1963), black = charcoal in Wardle (2001), yellow=swamp remains in Burrows (1980) and Burrows et al. (1981, 1984), brown = pollen localities (Clark et al. 1996; McGlone, 2001; McGlone et al. 1995), pink = moa coprolite in Wood et al (2012).

And it’s there that things become curious. In a study of the pollen record over the last few thousand years in the semi-arid interior of Central Otago, matai pollen was found to be common -up to about 10%  at 800 m asl in the Kawarau Gorge and up to 34% at 1400 m asl on the Old Man Range and to nearly 40% at 1450 m asl on Mt Tennyson  in the Nokomai (McGlone et al. 1995). For Mt Tenneyson they wrote (p.9): Tall podocarp trees have well dispersed pollen, and the high percentages of these types reflect extensive lowland and montane forests in the immediate region. For the Kawarau Gorge they concluded (p. 14):

Prumnopitys taxifolia, Dacrycarpus, Podocarpus, Hoheria/Plagianthus, and Metrosideros increase at the same time, indicating reafforestation of more distant areas, and the presence of local forest, possibly consisting of stands of species such as Plagianthus regius and Podocarpus hallii.

and:

We conclude that Phyllocladus/Podocarpus low forest-scrub dominated the Kawarau Gorge area, most likely as a mosaic of grassland and stands of divaricating and xeromorphic shrubs, and that tall podocarp forest never penetrated the region.

Subsequently, pollen from a lower site on the Old Man Range, the Earnscleugh Cave (540 m asl) was documented (Clark et al. 1996) where matai reached up to 20%. These authors wrote (Clark et al., 1996, p. 370):

The amount of podocarp pollen was substantial and the most likely explanation is that small stands of matai, totara, kahikatea and probably even rimu grew in the more sheltered and damper environments of the valley sides in this region.

and then (Clark et al., 1996, p. 375):

It is not entirely clear where the abundant podocarp tree pollen at these upland sites came from. The results from Eamscleugh Cave suggest that stands of podocarps, growing in the river valleys and gorges on the sides of the ranges, were the primary source of this upland pollen rain.

Two years later, another investigation of the palynology of Central Otago found up to 20% matai in the Ida Valley (McGlone and Moar 1998). These authors wrote (p. 97) that the matai (and some other podocarps):

most likely represent pollen rain from podocarp standsoutside the Idaburn valley region, as there is no other evidence for these podocarps ever having grown in this semi-arid area .

This seems like a step away from earlier comments, as there was no “other” evidence in those places either. This view was clarfied in McGlone (2001):

p. 4  It seems highly unlikely that Prumnopitys taxifolia was present within the semi-arid area, as it is now absent from central districts, and its altitudinal limit of 300- 600 m in the southern South Island (Hinds and Reid, 1957) makes it improbable that it could have had a presence in the higher rainfall forest zone on the upper slopes of the interior ranges.

and:

p. 8 Other than Podocarpus hallii, tall podocarp species were likely to have been almost entirely absent from the drier inland districts of Central Otago and south Canterbury. It is possible that occasional small stands grew in damp gorges, as suggested by Clark et al. (1996), but there is no direct evidence that they did so.

There is no problem with matai pollen blowing the distance from the coast to the interior – but it still has to dominate over the local taxa. At this point P. Wardle (2001) published the results of his investigation into buried logs and charcoals in the upper Clutha Valley. This extended the previous range of matai to Harwich (Mou Waho) Island within Lake Wanaka, and to sites around Lake Hawea. These are wetter areas, to the west of Central Otago proper. Intriguingly, at the same times as palynologists may be getting cold feet about matai in Central Otago, vegetation modellers have thrown a furfie. Walker et al. (2004) considered all the above evidence and wrote (p. 631):

Subfossil evidence and current distributions suggest that Prumnopitys taxifolia may have occurred locally on steep fans, scarps, and talus fringing the basin floors…

This is going much further than the palynologists cagey admission of matai to isolated mountain gullies and gorges – this is the edge of the Clutha Basin upstream of Cromwell and the Manuherikia upstream of Alexandra. In addition Walker et al. (2004, p. 633) wrote:

matai “may have occurred at least locally on the valley floors and lower slopes of the Shag and Taieri catchments

Native tree plantings on road-sides, parks, and other public places have really taken off in the last few decades, including in the drier parts of central South Island. Some of these are now established patches of broad-leaved angiosperms, at the right stage where some conifers – such as the matai, could be slipped in. Some effort should be made to reintroduce matai back to those areas where we know it once existed – using the genestock of the most marginal survivors.

References
Burrows, C. J. 1980: Some empirical information concerning the diet of moas. New Zealand Journal of Ecology 3: 125-130.
Burrows, C. J., McCulloch, B. & Trotter, M.M. 1981: The diet of moas based on gizzard contents samples from Pyramid Valley, North Canterbury, and Scaifes Lagoon, Lake Wanaka, Otago (New Zealand). Records Of The Canterbury Museum 9(6): 309-336.
Burrows, C. J., McSaveney, M. J., Scarlett, R. J. & Turnbull, B. 1984: Late Holocene forest horizons and a Dinornis moa from an earthflow on North Dean, North Canterbury (New Zealand). Records Of The Canterbury Museum 10(1): 1-8.
Clark, G. R., Petchey, P., McGlone, M. S. & Bristow, P. 1996: Faunal and floral remains from Earnscleugh Cave, Central Otago, New Zealand. Journal of the Royal Society of New Zealand 26(3): 363-380.
Cox, J. E. & Mead, C. B. 1963: Soil evidence relating to post~glacial climate on the Canterbury Plains. Proceedings of the New Zealand Ecological Society 10: 28-38.
GBIF: Matai distribution courtesy of New Zealand National Plant Herbarium (CHR), New Zealand Biodiversity Recording Network, New Zealand National Vegetation Survey Databank, (all LCR), (Accessed through GBIF Data Portal, data.gbif.org,  30.04.13).
Holloway, J. T. 1954: Forests and climates in the south island of New Zealand. Transactions of the Royal Society of New Zealand 82: 329-410.
McGlone, M. S. 2001: The origin of the indigenous grasslands of southeastern South Island in relation to pre-human woody ecosystems. New Zealand Journal of Ecology 25: 1-15.
McGlone, M. S., Mark, A. F. & Bell, D. 1995: Late Pleistocene and Holocene vegetation history, Central Otago, South Island, New Zealand. Journal of the Royal Society of New Zealand 25(1): 1-22.
McGlone, M. S. & Moar, N. T. 1998: Dryland Holocene vegetation history, Central Otago and the Mackenzie Basin, South Island, New Zealand. New Zealand Journal of Botany 36: 91-111
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