Northern Myanmar Vegetation

Plant Formations in the Northern Myanmar BioProvince

Peter Martin Rhind

Northern Myanmar Tropical Evergreen Forest These forests, which have much in common with the equatorial rainforests of Malaysia, are characteristic of lowland areas extending to an altitude of no more than about 2000ft. North of Myitkyina, they fill the main valleys and extend over much of the Hkamti Plain. The main canopy trees are between 80 and 120 ft tall and typically have unbranched, straight trunks. The canopy is often multi-coloured with many shades of green mixed with hues of bronze, purple, scarlet and yellow. Canopy trees typically include Dipterocarpus alatus, Mesua ferrea and Terminalia myriocarpus, while below these a lower storey comprises many small trees and shrubs such as Aporosa dioica, Baccaurea ramiflora, Callicarpa floribunda, Clerodendron nutans, Croton joufra, Kydia calycina, Mussaenda roxhburghii, Ordisia floribunda, Sarcosperma katchinense, Sterculia coccinea, Vernonia alpinii and Wendlandia tinctoria. Some of the more bizare looking species include the screw pine Pandanus furcata and the tall palm Caryota urens. The three support many climbers like Aspidopterys obcordata, Beaumontia grandiflora, Thunburgia racemosa, Toxocarpus himalensis and the endemic Bauhinia pottingeri (Fabaceae). Along the the sandy river banks, often forming a belt in front of the jungle, occur a number of interesting plants including many endemic species such as Camellia stenophylla (Theaceae), Elaeagnus rivularis (Elaeagnaceae), Strobilanthes arenicolus (Acantaceae), Syzygium aciculinum and Syzygium cuttingii (Myrtaceae), while in the more stoney ground along the river edge the strange looking Cryptocoryne cruddasiana can be found. Other endemics found in these forests include Albizzia vernayana (Fabaceae), Agapetes wardii (Ericaceae) and Rauwolfia rivularis (Apocynaceae).

Northern Myanmar Subtropical Hill Jungle At about 3000ft the tropical rainforest slowly gives way to subtropical jungle, which is recognized by its smaller trees and increasing presence of oaks, chestnuts, laurels, tree ferns, palms (mainly climbing species), bamboos and pandanas. There is also a corresponding decline in the numbers of strangling figs. The characteristic tree species include Aesculus assamicus, Albizzia vernayana, Bauhinia variegata, Betula alnoides, Carpinus viminea, Castanopsis argentea, Engelhardtia spicata, Illicium cambodianum, Lithocarpus viridus, Litsaea brachypoda, Magnolia pterocarpa, Manlietia caveana, Michelia punduana, Talauma hodgsoni, Tetrameles nudiflora, Ulmus lanceaefolia and the endemic Acer chionophyllum, A. pinnatinervium (Aceraceae) and Eriobotrya platyphylla (Rosaceae). Below the canopy is an under storey of shrubs including Buddleja asiatica, Daphne papyracea, Eurya chinensis, Rubus indotibetanus, Stryrax serrulatus, Viburnum cylindrium and the endemic Brassaiopsis trilobata (Araliaceae) and Symplocos araioura (Symplocaceae). The trees support a wealth of climbers and lianas such as Gelsemium elegans Jasminum pericallianthum, Kudsura heteroclita, and Lonicera hildebrandi, together with endemics like Illigera nervosa (Hernandiaceae) and Stachyurus cordatula (Stachyuraceae). In these forests epiphytes are also more abundant than in the tropical zones including several endemic species such as the epiphytic rhododendrons Rhododendron dendricola and R. taronense (Ericaceae). Among the many notable herbaceous species are the spectacular ground orchids such as Cypripedium villosum and the endemic Paphiopedium wardii (Orchidaceae). Other endemic species associated with these jungles include Agapetes adenobotrys, A. pubiflora (Ericaceae), Brachytoma wardii (family?), Lactuca gracilipetiolata (Asteraceae), Lasianthus wardii (Rubiaceae), Maesa marianae (Myrsinaceae), Ophiorrhiza lignosa (Rubiaceae), Saurauja subspinosa

Northern Myanmar Subtropical Pine Forest Between about 2000 and 7000ft above the Ngawchang Valley between Htawgaw and Gangfang the forests are dominated by pine and oak. The pine is Pinus insularis while the associated oaks include Quercus griffithii, Q. incana and Q. serrata. Among the many substorey shrubs are Dipentodon sinicus (the sole representative of the family Dipentodonaceae), Gaultheria griffithiana, G. yunnanensis, Litsaea euosma, L. forrestii, L. moupinensis, Pieris ovalifolia, Vernonia clivorum, Wendlandia speciosa, and the endemic Vernonia adenophylla (Asteraceae). In some of the less exposed areas and in ravines where Pinus insularis is less dominant, many other tree species may be encountered including Acer laevigatum, Alnus nepalensis, Altingia excelsa, Elaeocarpus dubius, Podocarpus neriifolia, Prunus cerasoides, Schima argentea, together with various endemic species such as Gordonia axillaris (Theaceae), Rhodoleia forrestii (Rhodoleiaceae) and Wightia alpinii (Scrophulariaceae). The shrubs in these sheltered areas include Aucuba humalaica, Berberis bicolor, Clethra delavayi, Conylopsis manipurensis, Lucula intermedia, Mahonia lomariifolia, Microtropis discolor and several endemics including Berberis incrassata (Berberidaceae), Dendropanax burmanicus (Araliaceae) and Sporoxeia sciadophyllum (Melastomataceae). Climbers tend to be small but quite numerous - typical species include Mezoneurum cucullatum, Prenanthes volubilis and Sabia ritchiae. Epiphytes, on the other hand, are few and inconspicuous being chiefly ferns and small orchids. Also very different from the hill jungle is the distinctive herbaceous ground flora, which includes species that hardly occur anywhere else in North Myanmar. These include Aeginetia indica, Anemone begoniifolia, Anisodenia pubescens, Euphorbia cyanophylla, Gentiana cephalantha, Gerbera piloselloides, Inula cappa, Lilium bakerianum, L. ochraceum var. burmanicum, Primula denticulata, Senecio densiflora and the endemic orchid Paphiopedilum wardii. (Orchidaceae).

Northern Myanmar Warm Temperate Rain Forest Above the pine forest at about 6000ft there is a gradual change from tropical to temperate conditions and evergreen forest gives way to deciduous forest. Here there is a well- marked summer and winter with occasional frosts and snow. The characteristic trees are Alnus nepalensis, Betula cylindrostachya, Bucklandia populnea, and for the first time rhododendrons make their appearance. These include Rhododendron stenauulum and the two endemic species R. eriogynum and R. kyawi (Ericaceae). A particular characteristic of this zone is the large number of epiphytic shrubs including several rhododendrons and species of Aeschynanthus, Agapetes, Ficus and Pentapterygium. Other epiphytes include the endemic Begonia hymenophylloides (Begoniaceae) and the large stem-clasping semi- epiphyte Wightia alpinii (Scrophulariaceae) that is also endemic. The woody climbers are mainly northern genera like Clematis and Lonicera but climbing palms (Calamus and Daemonorops) are locally common, while herbaceous species include several members of Asteraceae like Cucubalus bacciferus Mikania scandans, Senecio scandans and the endemic Prenanthes volubilis (Asteraceae). Compared with the densely vegetated forest below herbaceous flowering plants are more frequently, and include many northern genera such as Anemone, Oxalis, Primula, Ranunculus and Viola, but some of the species, such as Primula dictyophylla (Primulaceae) are endemic. Other endemics associated with these forests are Aeschynanthus wardii (Gesneriaceae), Aster helenae (Asteraceae), Camelia wardii (Theaceae), Coelogyne ecarinata (Orchidaceae), Dactylicapnos grandifoliata (Fumariaceae), Diplycosia alboglauca and D. pauciseta (Ericaceae), Gamblea longipes (Araliaceae), Ixora kingdon-wardii (Rubiaceae), Leycesteria insignis (Caprifoliaceae), Litsaea brachypoda and L. cuttingiana (Lauraceae), Peliosanthes longibracteata

Copyright © 2010 Peter Martin Rhind (Liliaceae), Photinia myriantha (Rosaceae), Pygeum cordatum (Rosaceae), Senecio pentanthus (Asteraceae), Sorbus paucinervia (Rosaceae), Syzygium stenurum (Myrtaceae) and Viburnum cuttingianum (Caprifoliaceae).

Northern Myanmar Cool Temperate Rain Forest At heights above 6000ft a cool temperate forests starts to develop characterized by the appearance of many large shrubby rhododendrons. In fact, this flora has more in common with the Himalayas than it does with the mountainous areas of the Indo-Malayan region. The more common rhododendrons include R. bullatum, R. cringerum, R. decorum, R. neriiflorum, R. panikimense together with endemic species such as R. butyricum and R. magnificum (Ericaceae). Accompanying these are many broad-leafed deciduous trees including ash, birch, cherries, laurels, maples and species of Schima, Sorbus, Gordonia and Tetracentrum. There is also a wealth of shrubs especially in the more open areas including several endemic species such as Agaptes pseudo-griffithii, A vernayana (Eriaceae), Berberis incrassata (Berberidaceae), Eurya urophylla, E. wardii (Theaceae), Lindera vernayana, L. wardii (Lauraceae), Sorbus apiciden and S. deter-ibilis (Rosaceae). The herbaceous flora of these open places includes the endemic Primula burmanica (Primulaceae). Other endemics associated with these forests include Acer chloranthum (Aceraceae), Eriobotrya wardii (Rosaceae), Euonymus burmanica (Celastraceae), Ilex cyrtura, I. wardii (Aquifoliaceae), Rhododendron agapetum, R. insculptum, R. taggianum (Ericaceae), Rubus chaetocalyx, R. wardii (Rosaceae) and Sporoxeia sciadophylla (Melastomataceae).

Northern Myanmar Mixed Temperate Forest These forests form a narrow belt between 8000 and 9000ft and represent a transition forest between the broad-leafed forests below and the silver fir forests above. They are characterized by a mixture of broad-leafed trees (both evergreen and deciduous), and conifers. In fact, the zone is a biodiversity hotspot for the former with many cherries, magnolias, maples, oaks, rhododendrons and so on. Typical species include Acer wardii, Lithocarpus pleiocarpus, L. xylocarpus, Magnolia rostrata, Magnolia mollicomata, Prunus cerasoides, Quercus lamellosa, Tetracentron sinense and the endemic Prunus kingdonwardii (Rosaceae). There are also several Ilex species including I. dipyrina, I. yunnanensis and two endemic species I. burmanica and I. melanotricha. (Aquifoliaceae). One of the characteristic rhododendrons is R. genestierianaum, which with its tiny plum- purple flowers and willow-like leaves, snowy white beneath, is unlike any other rhododendron. Others include the endemic epiphytic, yellow flowered shrubs R. butyricum and R. seinghkuense. Conifers include Larix griffithii, Picea brachytyla and surprisingly Taiwania cryptomerioides, which was previously known only from Taiwan and then later from southeast Yunnan. This discontinuous distribution with some 2000 miles of apparently suitable country separating the Taiwan and Yunnan populations indicate that it is probably a geologically ancient species - a living fossil - and that its ancient distribution was much wider than it is today. Other endemic species associated with these forests include Acer taronense (Aceraceae), Berberis hypoherina (Berberidaceae), Photinia rufa (Rosaceae), Rhododendron vesiculiferum (Ericaceae), Sorbus paucijuga and S. verticillata (Rosaceae).

Northern Myanmar Silver Fir Forest Dominated by Abies fargesii these forests form a belt extending between about 9000 - 12000ft where the winters are hard and snow lies for a month or more each year. From a distance they look like mono-specific stands of fir, but closer inspection reveals a rich under storey of colourful rhododendrons including R. arizelum, R. sidereum, R. sino- grande and various endemics such as R. beanianum, R. imperator, R. myrtilloides and R.

Copyright © 2010 Peter Martin Rhind pruniflorum (Ericaceae). Other small trees are Corylus ferox and the endemic Sorbus wardii (Rosaceae). There are few climbing plants or epiphytes except mosses, but the herbaceous ground flora can be very rich especially in the more open areas. Primulas are particularly numerous with several endemic species such as Primula eucyclia and P. siphonanthes (Primulaceae). Other endemic species found here include Berberis burmanica (Berberidaceae), Leptodermis wardii (Rubiaceae) and Gaultheria minuta (Ericaceae).

Northern Myanmar Rhododendron Sub-Alpine Scrub At about 12000ft, where snow lies for at least 5 months of the year, the forests give way to a belt of scrub characterized by a great variety of rhododendrons. Among these Rhododendron praestan has the distinction of being one of the world’s highest tree species occurring, for example, at 12000 ft in the Adung Valley, but most rhododendrons at this height are shrubs or dwarf species. In fact, the latter resemble heather, but with flowers of many colours. Typical species include R. anthopogon, R. arizelum, R. campylogynum, R. cerasinum, R. chryseum, R. crebreflorum, R. eclecteum, R. hypolepidotum, R. luridum, R. niphargum, R. pruniflorum, R. pumilum, R. repens, R. saluense, R. sanguineum, R. selense, R. tephropeplum, R. trichocladum, R. tsarongense together with endemics such as R, calciphila, R. calostrotum, R. chamaetortum and R. keleticum (Ericaceae). Primulas are also plentiful with some species like Primula melanodonta and P. sikkimensis forming colonies. Other colony forming species include Cypripedium tibeticum, Nomocharis souliei, Omphalogramma souliei and somewhat surprisingly Caltha palustris. Many other species, such as Iris kumaonensis and Polygonum griffithii, form compact cushions. Other endemic species found in this zone include Cremanthodium wardii and C. farreri (Asteraceae) and Meconopsis violacea (Papaveraceae).

Northern Myanmar Alpine Turf and Scree Vegetation At heights approaching 14000 ft most of the plants are specialist alpine species growing in alpine turf or among rocks of scree slopes. These include mat-forming plants like Diapensia himalaica and Gentiana wardii, cushion-forming plants like Arenaria polytrichoides, woolly plants like Eriophyton wallichii and rosette plants like the endemic Meconopsis violacea (Papaveraceae). There are also a number of bulbous species of the genera Allium, Fritillaria and Lloydia. Shrubs here are chiefly dwarf forms such as Potentilla fruticosa and the two endemic rhododendrons Rhododendron crebreflorum and R. riparium (Ericaceae). The few other endemics found at these heights include Pedicularis nana (Scrophulariaceae) and the three primulas Primula chamaethauma, P. fea and P. triloba (Primulaceae).

References

Chatterjee, D. 1939. Studies on the endemic flora of India and Burma. Journal of the Royal Asiatic Society of Bengal, 5: 19-67.

Gopal, B. & Krishnamurthy, K. 1993. Wetlands of South Asia. In: Wetlands of the World: Inventory, ecology and management. Vol. 1. Eds. D. Whigham, D. Dykyjova & S. Hejny. Kluwer Academic Press. Not used yet

Nath, P. C., Arunachalam, A., Khan, M. L., Arunachalum, K. & Barbhuiya, A. R. 2005. Vegetation analysis and tree population structure of tropical wet evergreen forest in and

Rao, A. S. 1974. Vegetation and Phytogeography of Assam - Burma. In: Ecology and Biogeography in India. Ed. M. S. Mani. Dr W. Junk Publishers. The Hague.

Stamp, L. D. 1924. The Vegetation of Burma from an Ecological Standpoint. University of Rangoon.

Ward, F. K. 1944/45. A sketch of the botany and geography of north Burma. Journal of the Bombay Natural History Society, vol.44: 550-574, vol.45: 16-30, 133-148.

Ward, F. K. 1946. A sketch of the botany and geography of north Burma. Journal of the Bombay Natural History Society, 46: 381-390.

Ward, F. K. 1946. Additional notes on the botany of North Burma. Journal of the Royal Horticultural Society, 71: 318-325.