Nothofagus, also known as thesouthern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere, found across southern South America (Chile, Argentina) and eastern and southeast Australia, New Zealand,New Guinea, andNew Caledonia.[3] The species are ecological dominants in many temperate forests in these regions.[4] Some species are reportedly naturalised in Germany and Great Britain.[5] The genus has a rich fossil record of leaves,cupules, and pollen, with fossils extending into the lateCretaceous period and occurring in Australia, New Zealand, Antarctica, and South America.[6]
The leaves are toothed or entire,evergreen ordeciduous. The fruit is a small, flattened or triangularnut, borne incupules containing one to seven nuts.
Many individual trees are extremely old, and at one time, some populations were thought to be unable to reproduce in present-day conditions where they were growing, except bysuckering (clonal reproduction), being remnant forest from a cooler time.Sexual reproduction has since been shown to be possible.[7]
The genusNothofagus was first formally described in 1850 byCarl Ludwig Blume who published the description in his bookMuseum botanicum Lugduno-Batavum, sive, Stirpium exoticarum novarum vel minus cognitarum ex vivis aut siccis brevis expositio et descriptio.[8][9]Nothofagus means "false beech", which Blume chose to indicate thatNothofagus species were different from beeches in theNorthern Hemisphere.[10]
In the past, they were included in the familyFagaceae, but genetic tests revealed them to be genetically distinct,[11] and they are now included in their own family,Nothofagaceae.[11] This taxonomy was introduced in 1962 by Russian botanist and palynologist Ludmila Andreyevna Kuprianova, who used pollen traits to erect Nothofagaceae.[12] A study in 1999 found that the pollen exine ultrastructure ofNothofagus differs from that of Fagaceae genera by its thickness, type of aperture, and ornamentation, reinforcing the placement ofNothofagus in its own family.[13]
Four subgenera are recognized, based on morphology and DNA analysis:[14]
SubgenusFuscospora, six species (N. alessandri, N. cliffortioides, N. fusca, N. gunnii, N. solandri, andN. truncata) in New Zealand, Tasmania, and southern South America.
SubgenusLophozonia, seven species (N. alpina, N. cunninghamii, N. glauca, N. macrocarpa, N. menziesii, N. moorei, andN. obliqua) in New Zealand, Australia, and southern South America.
SubgenusNothofagus, five species (N. antarctica, N. betuloides, N. dombeyi, N. nitida, andN. pumilio) in southern South America.
SubgenusBrassospora (orTrisyngyne), 20 accepted species (N. aequilateralis, N. balansae, N. baumanniae, N. brassii, N. carrii, N. codonandra, N. crenata, N. discoidea, N. flaviramea, N. grandis, N. nuda, N. perryi, N. pseudoresinosa, N. pullei, N. recurva, N. resinosa, N. rubra, N. starkenborghiorum, N. stylosa, andN. womersleyi) in New Guinea and New Caledonia.
Further reinforcing the four-clade model is their reproductive isolation from each other—naturally occurring and cultivatedNothofagus have been recorded only between species of the same subgenus.Fuscopora,Lophozonia, and theNothofagus subgenus often grow side-by-side, with plenty of opportunities to hybridize. Endemic to Papua New Guinea and New Caledonia,Brossospora does not occur in areas with other subgenera.[15]
In 2013,Peter Brian Heenan andRob D. Smissen proposed splitting the genus into four, turning the four recognized subgenera into the new generaFuscospora,Lophozonia andTrisyngyne, with the five South American species of subgenusNothofagus remaining in genusNothofagus.[14] The two authors posited that the four clades have evolutionary equivalence with other Fagales genera, and that the morphological and molecular differences are pronounced enough to raise the subgenera a rank. The proposed new genera are not accepted at theWorld Checklist of Selected Plant Families.[5][16]
Nothofagus first appeared in Antarctica during the earlyCampanian stage (83.6 to 72.1 million years ago) of theLate Cretaceous. During the CampanianNothofagus diversified and became dominant within Antarctic ecosystems, with the appearance of all four modern subgenera by the end of the stage.Nothofagus shows a progressive decline in the Antarctic pollen record through theMaastrichtian, before substantially recovering after theCretaceous-Paleogene boundary.[21]Nothofagus persisted in Antarctica deep into the Cenozoic, despite the increasingly inhospitable conditions, with the final records from the lateNeogene, around 15-5 million years old, which were small tundra-adaptedprostrate shrubs, similar toSalix arctica (Arctic willow).[22]
Nothofagus first appeared in southern South America during the late Campanian. During the Paleocene and Eocene they were mostly restricted to southern Patagonia, before reaching a peak abundance during the Miocene. Their distribution contracted westwards during the late Miocene due to the aridification of Patagonia.[23]
Although the genus now mostly occurs in cool, isolated, high-altitude environments attemperate andtropicallatitudes, the fossil record shows that it survived in climates that appear to be much warmer than those thatNothofagus now occupies.[24]
The pattern of distribution around the southernPacific Rim suggests the dissemination of the genus dates to the time when Antarctica, Australia, and South America were connected in a common land-mass orsupercontinent referred to asGondwana.[25] More recent studies suggest that theAntarctic land bridge likely played a major role in the dispersal of the genus between these continents.[26] However, genetic evidence usingmolecular dating methods has been used to argue that the species in New Zealand and New Caledonia evolved from species that arrived in these landmasses by dispersal across oceans.[27] Uncertainty exists in molecular dates and controversy rages as to whether the distribution ofNothofagus derives from the break-up of Gondwana (i.e.vicariance), or if long-distance dispersal has occurred across oceans. In South America, the northern limit of the genus can be construed asLa Campana National Park and theVizcachas Mountains in the central part of Chile.[28]
Nothofagus species are used as food plants by thelarvae ofhepialidmoths of the genusAenetus, includingA. eximia andA. virescens.Zelopsis nothofagi is a leaf hopper, endemic to New Zealand, which is found onNothofagus.
Cyttaria is genus ofascomycetefungi found on or associated withNothofagus in Australia and South America.Misodendrum are specialist parasitic plants found on various species ofNothofagus in South America.[29] Additionally, the beetle,Brachysternus prasinus, has been known to live inNothofagus in Chile and in parts of Argentina. The geographic range ofB. prasinus is highly dependent on the availability and distribution ofNothofagus on whichB. prasinus is believed to feed.B. prasinus have been observed in theNothofagus forests near the cities of Coquimbo and Llanquihue in Chile as well as the areas ofNeuquén and Chubut in Western Argentina.[30]
The species of subgenusBrassospora are evergreen, and distributed in the tropics of New Guinea, New Britain, and New Caledonia. In New Guinea and New BritainNothofagus is characteristic of lower montane rain forests between 1,000 and 2,500 metres (3,300 and 8,200 ft) elevation, occurring infrequently at elevations as low as 600 m (2,000 ft), and in upper montane forests between 2,500 and 3,150 m (8,200 and 10,330 ft) elevation.Nothofagus is most commonly found above theCastanopsis-Lithocarpus zone in the lower montane forests, and below theconifer-dominated upper montane forests.Nothofagus grows in mixed stands with trees of other species or in pure stands, particularly on ridge crests and upper slopes. TheCentral Range has the greatest diversity of species, with fewer species distributed among the mountains of western and northern New Guinea, New Britain, and Goodenough and Normanby islands.[29]
The New Caledonian species are endemic to the main island (Grand Terre), most commonly on soils derived fromultramafic rocks between 150 and 1,350 m (490 and 4,430 ft) elevation. They occur in isolated stands, forming a low or stunted and irregular and fairly open canopy. The conifersAgathis andAraucaria are sometimes present as emergents, rising 10 to 20 m (33 to 66 ft) above theNothofagus canopy.[29]
Every four to six years or so,Nothofagus produces a heavier crop of seeds and is known as the beechmast. In New Zealand, the beech mast causes an increase in the population of introduced mammals such as mice, rats, andstoats. When the rodent population collapses, the stoats begin to prey on native bird species, many of which are threatened with extinction.[31]
The southernmost tree in the world is reportedly anN. betuloides, living in a stand on the windswept island of Isla Hornos, at the southern edge of the Tierra del Fuego archipelago. It is believed to be 41.[32]
^Veblen, Thomas; Hill, Robert; Read, Jennifer (1996).Ecology and Biogeography of Nothofagus Forests. New Haven, CT: Yale University Press.ISBN978-0-300-06423-0.
^Carpenter, RJ; Bannister, JM; Lee, DE; Jordan, GJ (2014). "Nothofagus subgenusBrassospora (Nothofagaceae) leaf fossils from New Zealand: A link to Australia and New Guinea?".Botanical Journal of the Linnean Society.174 (4):503–515.doi:10.1111/boj.12143.
^Hill, R.S.; Harwood, D.M.; Webb, P.-N. (1996). "Nothofagus beardmorensis (Nothofagaceae), a new species based on leaves from the Pliocene Sirius Group, Transantarctic Mountains, Antarctica".Review of Palaeobotany and Palynology.94 (1–2):11–24.Bibcode:1996RPaPa..94...11H.doi:10.1016/S0034-6667(96)00003-6.
^Pujana, Roberto R; Fernández, Damián A; Panti, Carolina; Caviglia, Nicolás (2020-12-31). "The micro- and megafossil record of Nothofagaceae from South America".Botanical Journal of the Linnean Society.196 (1):1–20.doi:10.1093/botlinnean/boaa097.ISSN0024-4074.
^Carpenter, RJ; Jordan, GJ; Macphail, MK;Hill, RS (2012). "Near-tropical early eocene terrestrial temperatures at the Australo-Antarctic margin, western Tasmania".Geology.40 (3):267–270.Bibcode:2012Geo....40..267C.doi:10.1130/G32584.1.
