A plant that seems to defy biogeographical and evolutionary rules: Dodonaea viscosa (Sapindaceae), part 2: wood density

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...continued from https://www.inaturalist.org/journal/milewski/99976-a-plant-that-seems-to-defy-biogeographical-and-evolutionary-rules-dodonaea-viscosa-sapindaceae-part-1#

INTRODUCTION

We have seen that Dodonaea viscosa is a fast-growing tall shrub or short tree (up to 10 m high, https://books.google.com.au/books/about/Trees_of_Southern_Africa.html?id=jtvZAAAAMAAJ&redir_esc=y), that is capable of colonising bare ground.

Based on this biological profile, D. viscosa might be expected to have light wood, economical for a rapid succesional turnover (https://www.researchgate.net/publication/381698504_Wood_Density_Functional_Trait_in_Plants).

In this Post, I point out the following:

Perhaps the most remarkable - and underappreciated - aspect of the biology of Dodonaea viscosa is the extreme density of its wood.

The exceptional nature of D. viscosa is shown, for example, by a comparison with the many other taxa of trees indigenous to New Zealand (see data at the end of this Post, with D. viscosa marked by ***).

RESULTS

Most trees in New Zealand have wood densities (specific gravity when air-dry) of about

  • 0.6 (gymnosperms), or
  • 0.7 (angiosperms).

The latter value is in line with typical 'hardwoods', e.g. English oak, which has a density of 0.72 (https://en.wikipedia.org/wiki/Quercus_robur).

In order to visualise what the range of values means:
In water, any wood with values < 1.0 floats, whereas any wood with values > 1.0 sinks.

Somewhat exceptional in the flora of New Zealand are the following trees.

Species with unusually light wood are

Species with unusually heavy wood are

Other references state the density for D. viscosa to be

The basic wood density (https://bsapubs.onlinelibrary.wiley.com/doi/10.1002/ajb2.1175#:~:text=While%20wood%20density%20has%20been,biomass%20from%20living%20tree%20volume. and https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/wood-density) of D. viscosa is

For comparison, the basic wood density of English oak (Quercus robur) is 0.646.

DISCUSSION

It is noteworthy that the spp. with the heaviest wood in New Zealand

  • belong to various families (Sapindaceae, Asteraceae, Oleaceae, Ericaceae, Myrtaceae), and
  • are small-bodied enough, in several cases, to be described as shrubs rather than trees.

Furthermore, in the Myrtaceae:
Metrosideros contains both

There is a clear finding that the wood of D. viscosa - despite this species being usually shrubby and short-lived, and functioning as a pioneer in the succession of vegetation - is the heaviest of any plant indigenous to New Zealand.

The wood of D. viscosa is also remarkably consistent worldwide, regardless of climate (https://bsapubs.onlinelibrary.wiley.com/doi/10.3732/ajb.90.4.532).

These findings are all the more puzzling considering the following:
Dodonaea viscosa is the only indigenous plant in New Zealand, capable of growing into a tree, that has a cosmopolitan distribution.

What emerges is the following new perspective on the nature of D. viscosa:
This species has

In D. viscosa, the real specialisation is in:

  • unpredictable intraspecific variation - vaguely described by an 'ochlospecies' concept - that is incongruent with subspeciation, ecotypy, or raciality, and
  • extreme density of wood.

This raises two basic questions about the natural history of D. viscosa, viz.

  • What is the natural lifespan in this species? and
  • How has the extreme lignification of its stems contributed to its unique success in colonising the world during the Pleistocene?

MY COMPILATION OF THE DATA

Reference: Kennedy et al. (2023) Wood density and stiffness of New Zealand native trees and shrubs. New Zealand Journal of Forestry Science 53: 13 (https://nzjforestryscience.nz/index.php/nzjfs/citationstylelanguage/get/acm-sig-proceedings?submissionId=315&publicationId=286&issueId=8).

The values are for density (specific gravity) of air-dry wood, for species of trees indigenous to New Zealand.

Conifers:

Araucariaceae:
Agathis australis 0.468-0.630

Cupressaceae:
Libocedrus bidwillii 0.344-0.416
Libocedrus plumosa 0.380

Podocarpaceae:
Dacrycarpus dacrydioides 0.429-0.492
Dacrydium cupressinum 0.455-0.754
Halocarpus biformis 0.554
Halocarpus kirkii 0.627
Lepidothamnus intermedius 0.766
Manoao colensoi 0.515-0.788
Pectinopitys ferruginea 0.625-0.658
Podocarpus laetus 0.619
Podocarpus totara 0.435-0.559
Prumnopitys taxiflora 0.534-0.787

Phyllocladaceae:
Phyllocladus toatoa 0.675
Phyllocladus trichomanoides 0.553-0.645

Monocotyledons:

Arecaceae:
Rhopalostylis sapida 0.401

Asparagaceae:
Cordyline australis 0.522
Cordyline indivisa 0.626

Dicotyledons:

Acanthaceae
Avicennia marina 0.701

Araliaceae
Meryta sinclairii 0.462
Neopanax arboreus 0.677
colensoi 0.722
Pseudopanax crassifolius 0.757
lessonii 0.674
Raukaua edgerleyi 0.581
simplex 0.576
Schefflera digitata 0.559

Asteraceae:
Brachyglottis repanda 0.681
Olearia furfuracea 0.783
ilicifolia 0.663
lacunosa 0.748
paniculata 1.120
rani 0.850
virgata 0.776

Atherospermataceae:
Laurelia novae-zelandiae 0.382-0.465

Chloranthaceae:
Ascarina lucida 0.500

Coriariaceae:
Coriaria arborea 0.618

Corynocarpaceae:
Corynocarpus laevigatus 0.791

Cunoniaceae:
Ackama rosifolia 0.485
Pterophylla racemosa 0.572-0.639
sylvicola 0.627-0.680

Elaeocarpaceae:
Aristotelia serrata 0.575-0.593
Elaeocarpus dentatus 0.562-0.708
hookerianus 0.514-0.568

Ericaceae:
Archeria traversii 0.688
Dracophyllum latifolium 0.779
traversii 0.615
Leucopogon fasciculatus 0.901

Fabaceae:
Sophora microphylla 0.766-0.804
tetraptera 0.884-0.961

Griseliniaceae:
Griselinia littoralis 0.763
lucida 0.655

Lamiaceae:
Vitex lucens 0.959-0.980

Lauraceae:
Beilschmiedia tarairi 0.591-0.888
tawa 0.637-0.761
Litsea calicaris 0.502-0.603

Loganiaceae:
Geniostoma rupestre 0.562

Malvaceae:
Entelia arborescens 0.137-0.281
Hoheria angustifolia 0.738
lyallii 0.747
populnea 0.793
Plagianthus regius 0.506

Meliaceae:
Dysoxylum spectabile 0.491-0.678

Monimiaceae:
Hedcarya arborea 0.584

Myrtaceae:
Kunzea ericoides about 0.760 (0.731-0.943)
Leptospermum scoparium 1.076
Lophomyrtus bullata 0.694
Metrosideros excelsa 0.915
robusta 0.710-0.915
umbellata about 1.040 (0.968-1.140)
Neomyrtus pedunculata 0.741
Syzygium maire 0.637

Nothofagaceae:
Nothofagus cliffortioides 0.596-0.661
fusca about 0.600 (0.490-0.780)
menziesii 0.419-0.700
solandri 0.609-0.790
truncata 0.615-0.782

Nyctaginaceae:
Ceodes brunoniana 0.226

Oleaceae:
Nestegis cunninghamii 0.790-0.995
lanceolata 0.825
montana 1.013

Onagraceae:
Fuchsia excorticata 0.788

Pararyphiaceae:
Quintinia serrata 0.620

Pennantiaceae:
Pennantia corymbosa 0.526

Piperaceae:
Macropiper excelsum 0.519

Pittosporaceae:
Pittosporum eugenioides 0.796
tenuifolium 0.807-0.955
umbellatum 0.827

Plantaginaceae:
Veronica parviflora 0.768
salicifolia 0.822

Primulaceae:
Myrsine australis 0.805-0.991
salicina 0.844

Proteaceae:
Knightia excelsa 0.721-0.785
Toronia toru 0.836

Rhamnaceae:
Discaria toumatou 0.819

Rousseaceae:
Carpodetus serratus 0.742-0.822

Rubiaceae:
Coprosma arborea 0.654
linariifolia 0.835
lucida 0.674
repens 0.599
robusta 0.664

Rutaceae:
Melicope ternata 0.808

Santalaceae:
Mida salicifolia 0.733

Sapindaceae:
Alectryon excelsus 0.854-0.916
***Dodonaea viscosa 1.179

Scrophulariaceae:
Myoporum laetum 0.630

Strasburgeriaceae:
Ixerba brexioides 0.648-0.675

Violaceae:
Melicytus lanceolatus 0.597
ramiflorus 0.654

Winteraceae:
Pseudowintera axillaris 0.643
colorata 0.645

Publicado el octubre 15, 2024 10:25 TARDE por milewski milewski

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