Lao Flora A checklist of plants found in Lao PDR with scientific and vernacular names 2 L. Inthakoun and C. O. Delang Lao Flora A checklist of plants found in Lao PDR with scientific and vernacular names Lamphay Inthakoun Claudio O. Delang Lulu Press First published 2008 by Lulu Enterprises, Inc. 860 Aviation Parkway, Suite 300 Morrisville, NC 27560 The book can be purchased or downloaded from http://lulu.com/lao_flora. Contents Introduction 1 Lao Flora Listed by Lao Script 13-121 Lao Flora Listed by Genus and Species 123-238 Introduction This introduction1 provides a brief synopsis of the forest habitats and ecoregions found in Lao PDR, as well as an overview of the related research on plant taxonomy. This is followed by a description of the structure and contents of the present volume and a citation of sources used to compile the present checklist. 1. Forest habitats and ecoregions in Lao PDR 1.1. Forest habitats Forest classifications can be vegetation-related (which implies that the factors used to distinguish forests are the physiognomic or floristic characteristics of the vegetation), biophysically- and climate-related (where broad environmental or geographic characteristics become the distinguishing factors), or management- related (which involves utilizing combinations of vegetation and non-vegetation criteria). These modes of classification are scale-specific: while global-scale classifications are largely based on climatic criteria such as rainfall and temperature, classification systems used at country- or smaller regional-level scales emphasise floristic and physiognomic characteristics as well as physical site factors (Wong, Delang, Schmidt-Vogt, 2007). These latter variables were taken into account by the National Office of Forest Inventory and Planning (NOFIP) when it classified the forests of Lao PDR (Manivong and Sandewall, 1992). Applying this approach, the NOFIP derived the presence of eight different types of forests in Lao PDR. Dry dipterocarp forests This forest type occurs in open stands. In dry dipterocarp forests, the tree diameter is comparatively small, the crown is not widely spread out, and trees reach heights between 8 and 25 meters. This type of forest is normally found in places with shallow, often laterite, soil, where the hardpan emerges. On the poorest and shallowest soils, trees are crooked and do not exceed 10 meters in height. Many characteristic species of dry dipterocarp forests, such as Dipterocarpus intricatus, Shorea obtusa, Dipterocarpus obtusifolius, Terminalia tomentosa and Shorea siamensis have a thick bark and are fire resistant. 1 This introductory chapter borrows from MAF and STEA (2003), and some passages are reproduced from that report. 2 L. Inthakoun and C. O. Delang Dry evergreen forests This forest type has often between 50% and 80% of evergreen trees and usually grows in deep soil. A number of species abound in dry evergreen forests but two to three species tend to dominate. This forest type is divided into ‘upper’ (greater than 200 meters above sea level) and ‘lower’ (less than 200 meters ASL) dry evergreen forest. Tree heights in the upper layer usually exceed 30 meters. Tree density in the lower layer prevents most sunlight from penetrating to the ground. Another characteristic of this forest type is the presence of climbers and lichens on tree stems. Bamboo is usually not found except where the canopy has been opened. Some typical species of this forest type are Hopea spp., Pterocarpus pedatus, Dipterocarpus alatus and Anisoptera spp. Mixed deciduous forests In these forests, deciduous tree species represent more than 50% of the stand. This type is also divided into upper and lower mixed deciduous forest, with a lower density of trees in the upper and lower layers than that found in dry evergreen forests. Most seedlings and saplings are deciduous. The crown cover of this forest type appears quite open with a considerable presence of bamboo and other undergrowth species. In moist areas there might be a lot of climbers, which can make it difficult to distinguish mixed deciduous forests from their dry evergreen counterparts. In dryer regions differences in forest type are more apparent. Some typical species of this forest type are Xylia xylocarpa, Pterocarpus macrocarpus, Terminalia alata, and Lagerstroemia calyculata. Gallery forests Gallery forests can be either evergreen or deciduous. In areas where streams are likely to overflow heavily, these forests often develop along the streams’ lower bank (both persistent and intermittent), forming a long band of forest with the streambed on one side and, for example, paddy fields on the other. The width of gallery forests can be as great as100 meters. Coniferous and mixed coniferous/broadleaf forests This combined forest type usually has only one canopy layer, which is quite open, but a high density of young-growth tree species is sometimes found below the canopy. Coniferous forests occur in cool climates from approximately 200 to about 2,000 meters ASL. Predominant species consist of two pines (Pinus kesiya and Pinus merkusii), but other coniferous trees such as Cunninghamia spp. may also be abundant. Mixed coniferous forests are also found within the same altitudinal range and constitute a transitional forest type between coniferous and broad-leaf categories. As the name of the classification type conveys, in these forests coniferous tree species are found together with either deciduous or evergreen species. These eight forest types are distributed at different ranges of altitude within the three regions (Southern, Central, and Northern) of Lao PDR (Table 1). Lao Forestry 3 Table 1: Distribution of eight forest types in Lao PDR Occurring forest types Range of altitude (meters ASL) Southern Central region Northern region region Dry dipterocarp forests 0 - < 1,500 0 - < 1,500 200 - < 1,500 Lower dry evergreen 0 - < 200 0 - < 200 Absent Upper dry evergreen > 200 < 2,000 > 200 - + 2,500 200 - < 2,000 Lower mixed deciduous 0 - < 200 0 - < 200 0 - < 200 Upper mixed deciduous 0 - < 2,000 0 - + 2,500 200 - < 2,000 Gallery forests 0 - < 1,500 0 - + 2,500 200 - < 2,000 Coniferous forests 200 - < 1,500 200 - < 2,000 1,000 - < 1,500 Mixed coniferous / 200 - < 1,500 200 - < 2,000 500 - < 2,000 broadleaf forest Source: Manivong and Sandewall (1992) 1.2. Ecoregions An alternative classification system to one that focuses on the physiological characteristics of forests is that which focuses on ecoregions. An ecoregion is an area that is relatively homogeneous and distinct from others because of a combination of climatic, geological, hydrological, geomorphological, pedological, ecological, vegetative, wildlife, and perhaps human factors. Contiguous and biogeographically similar ecoregions can be conceived as a single ‘ecoregion complex’. The World Wildlife Fund (WWF) coordinated the identification and assessment of ecoregion complexes covering central and southern Lao PDR, central and southern Vietnam, and Cambodia (Baltzer et al., 2001). Using the factors listed above to guide classification, the following ecoregions can be considered of high international significance for conservation in Lao PDR. Northern Highlands The mountains of the north are biogeographically distinct from the Annamites in the central and southern parts of the country, with different species assemblages. Although these ranges have received less scholarly attention than the Annamites, they are nonetheless an important ecoregion. Representative examples of Laos’ Northern Highlands can be found in northern National Biodiversity Conservation Areas (NBCAs) such as Nam Ha, Phou Dene Din, Nam Et and Phou Loey. Evergreen Forests of the Annamite Mountains and foothills This is considered the most biologically distinctive ecoregion within the Forests of the Lower Mekong Ecoregion Complex (FLMEC). Species endemism is high for many taxa. These areas are typified by extremely wet forests formed by an interaction of monsoon patterns and local topography. Evergreen Annamite forests are found in neighbouring countries, but are probably most pristine in Lao PDR, due in part to lower human pressures. The Annamites proper are well 4 L. Inthakoun and C. O. Delang represented in the Nakai-Nam Theun, Xe Sap, and Dong Ampham NBCAs (although the biological communities in each conservation area are quite different). Annamite foothills are represented in such NBCAs as Nam Kading. Central Indochina Limestone Karst As in the Annamites, species endemism in the limestone karst ecoregion of central Indochina is high. It is represented in Lao PDR in the Phou Hin Poun and Hin Nam No NBCAs. Otherwise, these areas are found only in Vietnam. Bolaven Plateau This massif between the Mekong and the Annamites in southern Lao PDR is highly distinctive in the FLMEC. It occurs only in Lao PDR, and part of it is protected in only one gazetted NBCA, Dong Houa Sao. Dry Dipterocarp Forests of the Mekong Plains Found mainly in areas of low elevation in southern Lao PDR, and characterized by relatively flat terrain, with grass and herbs growing under widely spaced deciduous trees (predominantly Dipterocarpaceae), these forests of the Mekong Plains are typically studded by permanent or seasonal bodies of water. These small pools are of high importance for a variety of wildlife, from large ungulates to rare water birds. This ecoregion is best represented in the Xe Pian NBCA. Mekong River The Lao PDR plays a central role in the conservation of biodiversity along the Mekong River. Large sections of the river flow through Lao PDR and along its border with Thailand. Lao PDR has the largest catchment area of the Mekong, and therefore plays a much more active role in the river’s biodiversity conservation than its western neighbour. The Mekong forms the boundary of a NBCA (Phou Xiang Thong), but biodiversity management here presently focuses solely on four major forest habitats, not the river itself. Because seasonal rainfall variation is high across most of the catchment area, the Mekong shows one of the largest seasonal changes in flow rates of all the world’s major rivers.