Thailandian Seasonal Evergreen Forest
These forests, which also include a few deciduous species, occupy northern sheltered, moist valleys and low hills to an altitude of about 900 m, and are widespread in the central highlands and on the south and southwest slopes of the Korat Plateau. They are well developed along large watercourses in open broad valleys where they often form distinct gallery forests. In these situations magnificent stands of lofty evergreen dipterocarps occur, especially Dipterocarpus turbinatus, while others may include Anisoptera costata, Dipterocarpus alatus, D. costatus, Hopea odorata, Shorea assamica, S. roxburgii, S. thorelii and Vatica cinerea. Although not as tall as the tropical evergreen forests of peninsula Thailand certain stands can reach heights of 35 m, but they have fewer dipterocarp species. In terms of structure they usually have three tree layers, while emergent trees are uncommon. Nevertheless, their canopies include a rich variety of species with at least 23 families represented. Some of the more typical include Ailanthus triphysa, Altringia excelsa, Antiaris toxicaria, Bischofia javanica, Dracontomelon dae, Irvingia malayana, Lagerstroemia balanse, Nyssa javanica, Pterogygota alata, Tetrameles nudiflora and Toona ciliata. The middle and lower tree layers also comprise many species including the two endemic or near endemic species Chisocheton siamensis (Meliaceae) and Mammea siamensis (Hypericaceae). Many of the taller trees have large buttresses including the evergreen Dracontomelon dae and the deciduous Tetrameles nudiflora. Like tropical forests cauliflory and ramiflory are frequent (e.g. Baccarea ramiflora and species of Ficus), and fagelliflory can be found in some species (e.g. Oroxylum indicum and Parkia leiophylla). The well-developed shrub layer includes Alchornia rugosa, Ardisia vestita, Barleria strigosa, Canthium horridum, Clausena excavata, Dendrocnide stimulans, Lepisanthes rubiginosa, Melodorum fruticosum, Sterculia lanceolata, and the cycad Cycas micholititzii. Palms are also common especially in the more moist places and along watercourses. The principal species are Areca triandra, Arenga pinnata, Caryota mitis, Livistonia speciosa, Pinanga gracilis and the endemic Wallichia siamansis (Arecaceae). Lianas are plentiful with at least 20 families represented. Examples of endemic species are Artabotrys siamensis (Annonaceae) and Randia siamensis (Rubiaceae). Finally ground layer herbaceous species are characterized by genera such as Alpinia, Aglaonema, Amorphophallus, Arisaema, Boesembergia, Catimbium, Ctenolophon, Curcuma, Globba, Hedychium and Tacca.
Thailandian Northern Lower Montane Forest
These forests cover the moist valley basins and slopes at altitudes ranging from 1000-1800 m. Here the forest composition is dominated by the families Fagaceae, Magnoliaceae, Lauraceae and Theaceae, while members of the dominant lowland families like Annonaceae, Diperocarpaceae, Meliaceae, Sapindaceae and so on become far less conspicuous. The principal trees are Actinodaphne henryi, Canarium subulatum, Castanopsis acuminatissima, Lithocarpus auriculatus, Quercus brandisiana, Paramichelia baillonii and Schima wallichii. Structurally they can be divided into three tree-layers, but have poorly developed undergrowth and there are few woody lianas. Examples of some of the smaller trees are Adinandra integerrima, Lindera pulcherrima, Symplocos racemosa and the two endemics Chionanthus sutepensis (Oleaceae) and Glochidion acuminatum var. siamensis (Euphorbiaceae). The endemic palm Wallichia siamensis (Arecaceae) may also be encountered. In the shady areas the rare root parasite Sapria himalayana (Rafflesiaceae) may also be found. Like its larger relative Rafflesia, it has striking large orange-red flowers. In parasitizes the two herbaceous climbers Parthenocissus himalayana and Tetrastigma serrulatum. The few other climbers are Gnetum montanum, Myxopyrum smilacifolium and Ventilago calyculata. Epiphytic shrubs, on the other hand, such as Agapetes hosseana and Rhododendron veitchianum are frequently found, and there are many epiphytic herbaceous species including the endemic orchid Vanilla siamensis. In areas affected by shifting cultivation, the secondary growth is often dominated by oaks such as Castanopsis fissa, while the herbaceous elements typically includes the two endemic species Hieracleum siamensis (Apiaceae) and Pedicularis siamensis (Scrophulariaceae). On exposed ridges and steep slopes where there is frequent soil erosion or where there are excessive anthropogenic impacts such as burning, cutting and grazing, the native pine Pinus kesiya becomes an important component.
Thailandian Northern Upper Montane Forest
At altitudes above 1800 m in the Northern Highlands this type of upland forest is now confined to just a few peaks such as Doi Inthanon. They are often no more than about 23 m in height and typically have a continuous, flat crowned canopy with no lower tree layers. At these altitudes most of the magnolias of lower levels have disappeared and a different assemblage of oaks are found including Castanopsis purperea, Lithocarpus aggregatus and Quercus glabricupula. Other characteristic trees are Acer laurinum, Beitschmiedia globularia, Cinnamomum tamala, Eury nitida, Gordonia dalylieshiana, Heliciopsis terminalis, Lindera thomsonii, Neolitsea foliosa, Schima wallichii and Symingtonia populnea. Among the smaller trees are Helicia formosana, Macropanax oreophilus, Myrsine semiserrata, Neocinnamomum caudatum, Osmanthus fragrans and Symplocos dryophila. Under the dense canopy, the undergrowth is generally sparse, but often includes a mossy ground layer, while in wet depressions bog mosses (Sphagnum) predominate. The few herbaceous elements include several endemic species such as Delphinium altissimum var. siamensis (Ranunculaceae) and Scabiosa siamensis (Dipsaceae). Shrubs, on the other hand, are mainly confined to the forest margins where the endemic Cornus oblonga var. siamica (Cornaceae) can be found. Large woody lianas are also absent, but there are a number of herbaceous vines such as Hedera himalaica, Jasminium dispermum, Streptoliron volubile and the endemic Amphicarpaea siamensis (Fabaceae). The typically crooked trees support a luxuriant epiphytic flora of flowering plants, ferns mosses and lichens including many orchids of the genera Bulbophyllum, Dendrobium, Eria, Luisia, Malaxis, Otochilus and Pholidota, comprising several endemic species.
Thailandian Northern Upper Montane Scrub
These uplands scrublands have been described as unique and support many endemic species. They are mainly confined to the crests of exposed barren summit areas of the limestone massif in the Chiang Dae District, and range in altitude from1900 and 2200 m. Despite being called scrublands they are overwhelmingly dominated by herbaceous elements including many temperate genera and species. The low growing shrubs, on the other hand, thrive in the many mossy cracks and crevices giving these communities the appearance of attractive rock gardens. The few trees include a scattering of gnarled oaks such as Quercus franchetii, Q. lanata, Q. semecarpifolia, the palm Trachycarpus martianus and the deciduous, hemi-epiphytic tree Wrightia speciosissima (Scrophulariaceae). Common shrubs are Cotoneaster franchetii, Indigofera dosua, Lespedeza harmsii, Luculia gratissima, Mahonia nepaulensis, Premna interrupta var. smitinandi, Rosa helenae, Sophora dispar, Viburnum atro-cyaneum, Zanthoxylum acanthopodium and the endemic Rhododendron ludwigianum (Ericaceae), which is noteworthy since most rhododendrons are calcifugous species. The parasitic shrub Hymenopogon parasiticus (Rubiaceae) can also be occasionally found on the epiphytic shrub Agapetes hosseana. The principal herbs are spread over at least 25 familes and include many endemic or near endemic taxa such as Corydalis siamensis (Fumariaceae), Delphinium altissimum var. siamensis (Ranunculaceae), Geranium lamberti subsp. siamense (Geraniaceae), Hypericum siamensis (Hypericaceae), Primula siamensis (Primulaceae), Saxifraga gemmipara var. siamensis (Saxifragaceae), Swertia calcicola (Gentianaceae) and Thalictrum siamensis (Ranunculaceae). By comparison with the upper montane forest, the epiphytic flora is not rich, but still comprises many orchids including several endemic species such as Dendrobium continale, D. wilmsianum and Luisia thailandica (Orchidaceae). The principal pteridophytes are Araiostegia pulchra, Asplenium antrophyroides, Cheilanthes farinose, Crypsinus griffithianus, Microsorium membranaceum, Polypodium amoenum and Selaginella repanda.
Thailandian Tropical Deciduous Forest
These can be broadly divided into mixed deciduous forest and deciduous dipterocarp forest. The former usually reach their best development on soils derived from limestone, while the latter is characteristic of soils derived from sandstone and quartzite with extensive stands on the sandstone formations of the Khorat Plateau. However, in some areas, such as on some of the drier slopes, the forest include elements of both these forest types. Notable families in the mixed deciduous forest are Fabaceae, Combretacaea, Lythraceae and Verbenaceae, but these forests are usually evenly mixed and rarely have any single species dominance; the exception being the occasional dominant stands of teak (Tectona grandis) encountered on the fertile alluvium soils of the valley plains. In general, these forests reach heights of 30 m or so and have three tree layers. Among the principal trees of the upper layer are Ailanthus triphysa, Anogeissus acuminata, Bombax ceiba, Butea monosperma, Cananga latifolia, Chukrasia velutina, Dillenia pentagyna, Eugenia cumini, Garuga pinnata, Gmelina arborea, Haldina cordifolia, Haloptelea integrifolia, Lagerstroemia calyculata, Spondias pinnata, Stereospermum colais, and the endemic Chionanthus velutinus (Oleaceae), Horsfieldia amygdalina var. macrocarpa, Knema andamanica subsp. peninsularis, Knema tenuinervia subsp. kanburiensis (Myristicaeae), Pithecellobium tenue (Fabaceae), Pterospermum grandiflorum and P. littorale (Sterculiaceae).
The middle and lower layers have equally rich assemblages of species including, for example, the three endemic or near endemic trees Cassa siamensis (Fabaceae) Grewia winitii (Tiliaceae) and Maerua siamensis (Capparidaceae). Undergrowth species are also numerous with many shrubs like Clausena excavata, Clerodendron serratum, Croton hutchinsonianus together with a variety of endemic or near endemics like Ardisia tristis (Myrsinaceae), Barleria siamensis (Acanthaceae), Capparis echinocarpa, C. siamensis (Capparidaceae) Enkleia siamensis (Thymelaeaceae), and many bamboos such as the endemic Thyrsostachys siamensis (Poaceae). Many of the climbers are also unique to these forests with endemics such as Alyxia thailandica, Ichnocarpus fulvus (Apocynaceae), Bauhinia winitii (Fabaceae), Jasminum annamense subsp and J. siamense (Oleaceae), Stephania crebra (Menispermaceae) and Tinospora siamensis (Meninspermaceae). The ground layer herbaceous species also comprise several endemics such as Fimbristylis prabatensis (Cyperaceae), Gentiana arenicola (Gentanaceae) and the hemi parasite Centranthera siamensis (Scrophulariaceae). The deciduous dipterocarp forests have a more open canopy with some trees reaching heights of 35 m, but in general they seldom exceed more than about 18 m. They can have either a two or three layered canopy, with the most characteristic upper layer species comprising several deciduous dipterocarps such as Dipterocarpus obtusifolius, D. tuberculatus, Shorea obtuse and the endemic or near endemic Shorea siamensis (Dipterocarpaceae). Other common trees include Canarium subulatum, Gluta usitata, Morinda pubescens, Sisyrolepsis muricata and the endemic Sindora siamensis (Fabaceae). The principal shrubs are Crotalaria bracteata, Ellipeiopsis cherrevensis, Holarrhena densiflora and the endemic Barbleria siamensis (Acanthaceae). Also frequently found in the shrub layer is the endemic cycad Cycas siamensis (Cycadaceae). The endemic Bauhinia strychnifolia (Anacardiaceae) is one of the many climbers. At ground layer, these forests are characterized by a conspicuous layer of graminoides including many dwarf bamboos and the endemic Eulalia siamansis (Poaceae).
Thailandian Tropical Evergreen Forests (information required)
Thailandian Coastal Sand Dunes
The coastal sand vegetation of Peninsular Thailand can be divided in to: 1. Sandbar vegetation caused by sedimentation from sea currents and include dune grassland, dune scrub and dune woodland, and 2. Sandbar vegetation caused by strong wind which include dune grassland and dune scrub.
Sandbar vegetation caused by sedimentation from sea current
East Coast
Natural sandbar vegetation on the east coast is thought to have extended from north of Chumphon throughout much of peninsular Malaysia. However, much has now been lost. Only fragmented remnants are left such as at “Chaiya sandbar” in Surat Thani. In Chaiya district, quite a few remnants of natural sandbar vegetation can be seen in fragmented patches along the Chaiya sandy coast from Ban Takrop to Ban Nuea.
Here the dune grassland typically includes Canavalia rosea, Chrysopogon orientalis, Ipomoea imperati, Ipomoea pes-caprae, Ischaemum muticum, Remirea maritima, Sesuvium portulacastrum, Spinifex littoreus, Vigna marina, Vitex rotundifolia and Zoysia matrella.
The dune scrublands charateristically comprise stunted, shrubby trees up to 8 m high. These include Acronychia pedunculata, Chaetocarpus castanocarpus, Eurycoma longifolia, Lannea coromendelica, Olea brachiata, Pouteria obovata, Rapanea porteriana, Syzygium gratum and Vatica harmandiana. Among the shrub species are Atalantia monophylla, Breynia racemosa, Catunaregam tomentosa, Melastoma malabathricum, Micromelum minutum, Rhodomyrtus tomentosa, Salacia chinensis and Suregada multiflorum. The ground layer may comprise Dianella ensifolia, Wikstroemia ridleyi, orchids such as Doritis pulcherrima, and ferns like Davallia denticulata and Drynaria sparsisora. Vines such as Cansjera rheedei, Dischidia major, Hoya parasitica and Psychotria sarmentosa may also be present but these tend to be scattered.
Dune woodland in the innermost zones typically has a three storey vertical structure. The canopy up to 18 m high mainly comprises Shorea roxburghii. The middle layer, which ranges from 10–12 m, mainly comprises Vatica harmandiana and Vitex pinnata. Shrubs and saplings make up much of the undergrowth with species such as Ardisia crenata, Carallia brachiata, Champereia manillana, Eurycoma longiflia, Ixora javanica, Microcos tomentosa, Micromelum minutum, Ochna integerrima, Olea brachiata, Pouteria obovata and Rapanea porteriana. The climbers include Ancistrocladus tectorius, Cansjera rheedei, Dischidia major, Hoya parasitica, Psychotria sarmentosa and Tetracera indica. The ground layer commonly includes ferns such as Davallia denticulata and Drynaria sparsisora, and herbs such as Dianella ensifolia. However, the species composition of these woodlands varies from place to place. At Ban Nuea the upper storey reaches heights of up to 30 m and consists of Dipterocarpus alatus and D. chartaceus. The lower layer (15–20 m) mainly includes Mangifera indica and Shorea roxburghii. The undergrowth, somewhat disturbed by human activities, still supports native species such as Ardisia crenata, Champereia manillana, Eurycoma longifolia, Memecylon ovatum, Morinda elliptica and Ochna integerrima.
West Coast
Much of the west coast vegetation has developed on narrow sandbars in small fragmented stands but almost all of the natural vegetation has been reduced or modified mainly due to the impact of tourism. However, there are a few remnants of natural sandbar vegetation left in some protected areas such as Khao Lampi-Hat Thai Mueang National Park, Thung Thale non-hunting areas and Hat Chao Mai National Park. The remnant patches at Hat Thai Mueang are fairly represenative of west coast vegetation but some was destroyed by the tsunami tidal waves of 2005. Here the outer dune scrub zone comprises Atalantia monophylla, Calophyllum pulcherrimum, Crinum northianum, Diospyros areolata, D. ferrea, Hydrophylax maritima, Ischaemum muticum, Pandanus odoratissimus, Pouteria obovat, Rhodomyrtus tomentosa and Scaevola taccada. The inner scrub zone is mainly formed by species characteristic of west coast sandbars but it tends to be scattered and often divided by small patches of other plant communities. Each stand is mainly composed of a shrubby tree species such as Cotylelobium lanceolatum and Rapania porteriana surrounded by other shrubs or treelets such as Rhodamnia cinerea, Rhodomyrtus tomentosa, Styphelia malayana and Syzygium gratum, while the ground layer typically includes orchids such as Doritis pulcherrima, Dendrobium crumenatum, Dendrobium indivisum and Dendrobium pachyphyllum.
The dune woodland develops as a continual narrow strip and usually charactrized by three storeys. The canopy at 15–18 m is dominated by dipterocarp species such as Shorea roxburghii. The lower layer at 8–10 m comprises smaller trees and shrubs such as Acronychia pedunculata, Pouteria obovata, Syzygium gratum and Vatica harmandiana. Typical undergrowth species are Calophyllum pulcherimum, Rhodamnia cinerea and Rhodomyrtus tomentosa and ferns such as Davallia denticulata, D. heterophylla, D. pectinata, Drynaria sparsisora, Pyrrosia piloselloides, Schizaea dichotoma and S. digitata are common. However, species composition varies from place to place.
Sandbar vegetation caused by wind storms
Only one site at Ban Bangboet, Pathio district, Chumphon, in the northernmost part of the peninsula is recognized and this is regarded as unique on the plain of the eastern coast of peninsular Thailand. Much of the vegetation is affected by strong winds but can recover quickly when a level of stability is achieved. The dune grassland includes Cyperus stoloniferus, Fimbristylis sericea, Ipomoea imperati and Ipomoea pes-caprae. Among the dune scrub species are shrubby trees and shrubs such as Ardisia crenata, Calophyllum pulcherimum, Diospyros ferrea, Eurycoma longifolia, Pandanus odoratissimus, Pouteria obovata, Sindora siamensis, Scaevola taccada and Syzygium gratum. Climbers and herbs typically include Dunbaria bella, Dianella ensifolia and Tetracera indica.
Further information required.
References
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