An Annotated Checklist and Atlas of the Mosses of
Welcome | Abstract | Introduction | Acknowledgments
Systematic Arrangement of Genera | Recognized Species
Checklist | Literature Cited
Geographical and Floristic Divisions
The topography and drainage of Thailand in part define the country
as four widely recognized geographical regions: the North (N),
Northeast (NE), Center (C), and South (S) (Map 1).
The four regions have no administrative significance, but each
differs from the others in population, basic resources, natural
features, and level of social and economic development. Thailand
is administratively divided into seventy-three districts (new
provinces) (Map 2) (LePoer 1989).
Botanically, Thailand is included in the Indochinese subdivision
of the continental southeast Asiatic region according to the recent
floristic divisions of the earth (Good 1974).
Thailand can be divided into seven floristic regions (Smitinand 1958)
(Map 3). They are: the Northern
(N), Northeastern (NE), Eastern (E), Central (C), SoutheasternSE),
Southwestern (SW), and the "Peninsula" (PEN). Bryologically,
Thailand is often divided into 18 natural regions (old provinces)
(Map 4) (Hansen 1961;
Touw 1968; Noguchi 1972,
1973). To illustrate the relationships among the geographical
regions (4), floristic divisions (7), natural regions (18), and
administrative provinces (73) of Thailand, I have incorporated
the data into a classification as shown in table 1.
The followings are descriptions of floristic features of each
division, including natural regions and districts (Note: roman
numerals before natural regions and alphanumeric numbers before
districts are corresponding to those shown in the maps). Geographical
units used for recording the distribution of mosses in Thailand
are shown in Map 3 and Map 4.
Northern division (N): This division is under
the Indo-Myanmaran floristic tendency. The region is rich in high
mountains, having the highest peak (Doi Inthanon, alt. 2576 m)
in Thailand. The geological formation is generally of sandstone
or granite. Types of forests are ranging from dry dipterocarp
forest below 500 m, dry evergreen forest between 500 to 1000 m,
and to dry hill evergreen forests above 1000 m (Smitiand 1958).
Both historically and in recent times, northern Thailand has received
the most attention of botanists who collected bryophytes. The
division includes four natural regions and 18
Northeastern division (NE): This region corresponds
to the Indochinese flora, but the Indo-Myanmaran elements can
also be found here. Floristic affinities are close to southwestern
China as well. The region is the high plateau of Thailand. Types
of forests are from dry deciduous to mixed deciduous forests with
large tracts of dry evergreen forests growing intermittently.
Pine forests are present from above 1000 m. Dipterocarp forests
are the common feature of the region. A significant number of
bryophytes have been collected from this region. This division
includes two natural regions and 10 provinces.
Eastern division (E): This region is under
the influence of the central and southern Indochinese flora. Dry
dipterocarp forests are the main feature of the region. Savannas
are also common. Pine forests can be seen side by side or mixed
with dry dipterocarp forests. No significant bryophyte collections
have been made from this region. This division includes two
natural regions and 7 provinces.
Central division (C): This division corresponds
with the southern half of Bangkok plain or central valley. The
region is mostly under cultivation. Virgin forests have almost
disappeared. The dipterocarps, once formed the evergreen forests
in the region, are scattered here and there nowadays. Little bryological
field work has been carried out in this area. The division includes three natural regions and 12 provinces.
Southeastern division (SE): This region is
under the influence of both southern Vietnamese and Malayan floras.
The dipterocarps together with Solenospermum and Parkia
form the predominating species in the tropical rain forests (Smitinand
1958). Savannas are also widespread in the plains. The common
low shrub species in the area is Dillenia hookeri, which
grows in common, scattered clumps. Rich mangrove swamps and tidal
forests are the dominant feature of the coastal line and along
the estuaries of the main rivers. Field work involving bryophyte
collecting has been relatively well undertaken in this region.
The division includes two natural regions and 7 provinces.
Southwestern division (SW): This region is
predominated by limestone formation and corresponds with the Lower
Myanmaran flora. Evergreen forests are usually present in remote
part of the region near the border between Myanmar and Thailand.
Bamboo forests and savanna scrubs are the common features of the
plains. The bamboo forests often gradually change into mixed deciduous
and dry dipterocarp forests. Only a small number of bryophytes
have been collected here mostly by collectors traveling from northern
to peninsular Thailand. This division includes one
natural region and 5 provinces.
The peninsular division (PEN): This region
is mostly under the influence of the Malayan flora. The Malayan
elements are fairly common in the region although in northern
part of the region Myanmaran elements are notably joined together.
The forests are mainly of the tropical rain forest type and are
made up of many dipterocarp species. Mangrove swamps in the region
are very rich and are the main mangrove-forests of the country.
They almost cover the whole western coast. A large number of bryophyte
collections have been made from this region. The division includes
four natural regions and 14 provinces.
Table 1. The Relationships between Geographic
Regions (GE), Floristic Divisions, Natural Regions, and Provinces