BURROWS: FOREST FLORA OF CANTERBURY 23 THE FOREST FLORA OF CANTERBURY: ECOLOGICAL INFERENCES C. J. BURROWS University of Canterhury Species lists have been collected for glabeJ/a. Pyrrosia serpens. tLycopodium varium. *L. forested and related scrubland areas through- voluNk. "'L. scario.wm. Tmesipteri.\' tannensis. out Canterbury. The total number of species HERS-S. involved is about 350. The patterns of dis- *Microlaena avenacea, tDanthonia cunningham;;, tributions reflect the influence of one or *Gahnia pauciflora, tUncinia uncinata, Astelia nervosa, a combination of several of the following Arthropodium candidum. Libertia ixioides, Dianella imer- factors: media, Earina nmcronata, *Pterostylis banks;;, tCorybas triloba, *Gastrodia cunninghamii, tVrtiea incisa, Austra. 1. The Pleistocene glaciation and sub- lina pusilla. Chenopodium triandrum, tRmwneulus hiI'. tus, Aeaena novae-zealandiae, *A. fissistipula, Linum sequent climate amelioration. monop,ynum, Haloragi:,' ereeta, Hydroeotyle moschata, Angelica geniculata, tSte/larii1 parviflora, *Nertera seW- 2. The differential migration potential losa, N. dicholldraefolia, tN. depres.w, *Galium umbro- and length of life of beech trees and .mm, *Wahlenbergia gracilis, tLagenophora petiolata, podocarp/hardwood species. *Erechrire.t prenanrhoides. 3. Climate deterioration within the last VINES. millenillm. Rhipogollum scandens, "'Muehlenbeckia australis, *Clemati.~ indivisa, *c. forsteri, *c. marata, *Rubus 4. Widespread fires from 500 to 800 years cissioides, R. schmide/ioide!-;, tR. squarrosus, Metro- ago. sideros ditJusa, Parsomia heterophylla, tP. capsularis, CaJystegia tuguriorum. 5. The existing climate, especially effec- tive rainfall, with relation to topog- PARASITES. raphy and degree of exposure. Lorant1ms micranthus, *Tupeia antarctica, Korthalsella 6. The advent of Europeans. Felling and lindsayi. burning. The effects of grazing animals. SHRUBS. Drimys c%rata. tPittosporum divaricatllm, Melicope Distribution patterns influenced by the simpll'x, Coriaria arborea, tAristotelia fruticosa, *Lepto- post-Pleistocene mild climate are found in spermum ericoides, Myrtus obcordata, tM. pedunculata, the presence of mosaics of podocarp and Fuchsia colensoi, tGaultheria antipoda, *Cyathodes broadleaved hardwood tree species and their lIcerosa, Leucopogon fasciculatus, tSu((onia divaricata, Tellcidillm parvitolium, Solanum aviculare, tHebe salici~ associated herbs, vines, shrubs and ferns folia. *H. traversii, *Coprosma lucida, C. robusta, C. throughout lowland Canterbury.. These in- rotundifolia. C. areolata, *c. rhamnoides, C. rigida, C. clu&: I'irescens, tc. linariifolia, i Diearia arborescens, to. avicenniaefolia, O. forsteri, O. fragrantissima, *0, lineata, PTERIDOPHYTES. Helichrysum glomeratum, Notospartium torulowm. Mecodiul1I sanguinolentum, '~M. rarum, tM. villosum, TREES. M. fiabellatum. *M. flexlwsum, *Meryngillm multifidum, *Hymenophyllum peltatum, Polyphlebium venosum, Dacrydium cupressinum. Podocurpus totara, P. Cya/hea dealbata, C. smith ii, Dicksonia squarrosa, Adlatl. spicatus, P. dacrydioides, Paratrophis microphyIia, film affine, Hypolepis (enul/olia. tHo mille/allum, Pel. tCarpodetus serratus, tPittosporum tenuifolium, p, toea rOlunc!ifolia. *Paesia scaberula, *Histiopteris incisa, eugenioides, tSophora microphyl1a, Pennantia corym- Blechnum paterson;. B. discolor, tB. lanceo/alum, *E. hosa, *Aristotelia serrata, *Elaeocllrpus hookerianus, E. procerum, tH. fi/lviatile, *8. vu/canicum, *Asplenium dent(l(u:,', Plagiantlws betulinus, Hoheria angustifolia, hookerial1um. A. bulbilerum, *A. colensoi, *A richardi, Melicytw' ramifloms, M. micranthus, *Fuchsia exeoTti- tA. flaccidum, A. lucidum var. fyolli;, CycJosorus penni- eata, Nothoparwx arboreum, N. anomalum, *Schefflera gera, *Sticherus cunninghamii, *Leptopteris hymenophyl- digitatQ, tPseudopanax crassifolium, tGriselinia littoralis, Joides, Ctenopteris grammitidis, *Microsorium diversi. *Metrosideros umbel/ata, Nothotagus so/andri sensu folium, tPolystichum vestitum, P. richardi, Ctenitis strictu. 24 BURROWS: FOREST FLORA OF CANTERBURY Numbers of these are also found usually var. cliffortioides. The broad patterns of dis- between 1000 and 2500 ft. in upland Canter- tribution of it and the other species N. fusca bury, accompanying beech forest in the and N. menziesii are, as shown by Holloway basins of the large rivers. (These are indi- (1954), partly determined by their differen- cated by an asterisk on the previous list.) tial migration rate and longevity com- Their distributions here often link with pared with podocarp and other those in true lowland and foothill areas. species, superimposed on the ancient distribution pattern after the retreat Other species form on upland facies of of ice from the glaciated valleys, podocarp broad leaved forest, with Liboce- together with effects of climate change and drus bidwillii and Podocarpus hal/ii the ancient fires. N. fusca appears to have con- dominants, growing in the heads of Rakaia tracted its area, being present only in the and Rangitata tributaries between 2000 and northern part of Canterbury with scattered 3500 ft. There are indications that the same outliers. N. menziesii and N. cliffortioides type of forest was once well developed at are found in the south and accompany N. high levels on Banks Peninsula, Seaward fusca in the north-west. N. menziesii also Kaikoura Range, Alford Forest and Mt. Hutt, appears to have had its area reduced as is Mt. Peel, Hunter Hills, in upper Waimakariri shown by its spot distributions. This process tributaries and widely in Tasman River, may have occurred in part during the post- Godley River and other McKenzie country glacial optimum. sites. The forest grades into a distinctive scrub community but many of the shrub The recent deterioration in climate (Rae- species grow in the forest proper and attain side 1948, Holloway 1954 and others) the size of trees. Species include numbers of has resulted in reduction of members of those already listed (marked with a dagger in both podocarp-broadleaved forest and beech the previous list) with important exceptions. forest to relict status in many places in Can- Additional species found here (many of terbury. Disjunct distributions show that them also in beech forest or scrub at high these species have once been more widely levels not near valley heads - marked with and continuously distributed. The long lived an asterisk) are: Podocarpus spicatus, P. dacrydioides, P. totara and Dacrydiwn cupressinum are now relict throughout. Weinmannia racemosa, FERNS. and Melicytus lal1ceolatus, extreme dis- Apieropteris maling;i. *Cyathea colellsoi, *Blechnum juncts, must be regarded as relict. It is minus, *Asplenium lrichomanes. probable also that species such as Elaeo- HERBS. carpus dentatus, Plagianthlls betulinus, *A.~teli(/ cockaynei, *Enargea parvi{fora, *MYOSOli.\" Olearia lineata, Hebe cupressoides, Metro- for.Herl, * Viola fi/kauUs. sideros umbel/ala, Rumohra hispida, Micro- SHR U BS. laena polYl1oda, Lindsaea cUl1eata and Gahl1ia *Podocarpus niva!is, *Phormium co/ensoi, *Olearia pauciflora, though able to regenerate in some haasEii, *0. cymbifolia, *0. nwnmularitolia, O. colensai, places, are in general in the same state. O. Jacunosa, O. iUd/olia, *Senecio bidwillii. S. eIeagni- folius. *5. ca.~sinioides, *Cassinia vauvilliasi, *Coprosma Beech forest has been enabled to expand hanksii, *C. pseudocu/lcota, *c. foetidissima, *c. co/en- sol, "'c. rugosa, C. ciliata, ."Dracophyllum longifofiunJ, at the expense of podocarp-broadleaved *Hebe vernicosa, *Nolhopanax colensoi, Archeria (ra- forest partly because of the decline in climate. versii. Patterns of invasion by mountain beech are TREES. present in Waimakariri, Rangitata and Rakaia valleys and on the foothills. Species Dacrydium hi/arme, Liboadms hidwiJIii, *Podocarpus halJii, *PhyllocladliS alpin us, DracophyJllim Jravcr.rii, found normally in intact podocarp-type Nothopanax simplex, Hoheria glabrala. forest (e.g. Carpodetus" seratus, Notho- panax anomalllm, Elaeocarpus hookerianus, It will be noted that this is very similar to Podocarpus hallii, Cyathea colensoi, Blech- the forests of upper levels in Westland. num vu/canicum, Metrosideros umbellata, Myrtus pedunculata) are found widely scat- Almost the sole species in beech forest in tered in otherwise pure mountain beech much of Canterbury . is Nothofagus solandri forest. Sometimes several such species exist BURROWS: FOREST FLORA OF CANTERBURY 25 as an island in a sea of beech. In areas where or others of its kind. Another is the develop- (in rain shadow zones from both north-west ment of a patch containing a few of one and south-west rain) rainfall has become species, remote from any others, e.g. Podo- deficient, even the hardy mountain beech has carpus hallii (often surrounded by a field of failed and forest is now fragmen tary or large boulders), Leptospermum ericoides, missing. This applies to a strip from the O/earia forsteri, Nothopal1ax arboreum, middle Clarence River through Lake Cole- Nothofagus solandri var. clitfortioides. A ridge to the middle Rangitata in a line. third involves the presence of a number of parallel to the main divide. so-called scrub hardwoods, e.g. Criselinia littoralis, Fuchsia excorticata, Melicytus The main feature of the climatic ehange ramifIorus, Nothopanax arboreum, forming in Can terbury within the last thousand years a small patch, with some ferns and shrubs has been a decline in rainfall of at least underneath, in a sheltered gully. On the 20 in.