Cambodia is unique in natural riches: the world’s largest natural freshwater lake fish, the Greater Mekong forests and river complex, and holding the largest contiguous block of natural forest remaining on the Asian continent’s mainland, an important constituent of the Indo-Burma Biodiversity Hotspot. Five of nine high priority biodiversity conservation corridors in the Greater Mekong Sub-region are in Cambodia.23 The country is a sanctuary to about 1.6% of globally threatened species on the IUCN’s Red List. This includes 2.5% of globally threatened mammals, 2% of globally threatened birds, and 5% of globally threatened reptiles. The list of globally threatened species is presented in Table 3, below.
Table . Species diversity records from national biodiversity reports
Taxon
4th Biodiversity Report
5th Biodiversity Report
Known Species
IUCN
Red-listed
Known Species
IUCN
Red-listed
Mammals
123
39
135
45
Birds
545
36
635
40
Reptiles
88
13
95
15
Fish
874
955
19
Amphibians
63
12
65
12
Vascular plants
2,308
38
4,500
50
Hard corals
24
24
Soft corals
14
14
Sea grass
10
10
Source: Adapted from the 4th Biodiversity Report 2010 and Forestry Administration 2013
The Eastern Plains Landscape forms possibly the largest intact block of forest in Southeast Asia and is home to a remarkable array of wildlife. The landscape is characterized by a mosaic of habitats, primarily due to the altitudinal and moisture gradients of the landscape which spans from the dry forest plains of the lower Mekong in the west, increasing in altitude with the southern Annamite Mountain range in the south and east, rising to over 1,000 m on the peak of Phnom Namlire. In the lower altitude regions, the primary habitat is deciduous dipterocarp forest, which has a relatively open canopy and a grassy understory. At the other end of the spectrum are the thick, tropical evergreen forests and the natural grasslands such as the Sen Monorom Plateau that are found at higher altitudes and are characterized by higher rainfall.
Studies have revealed that topographical position and distance to rivers has the strongest influence on the structure of evergreen and semi-evergreen forest types, they are found in locations where there is sufficient water supply throughout the year - along watercourses and associated with hills of sufficient altitude24. Species that occur in high frequency in evergreen habitats include Haldina cordifolia, Dimrocarpus sp., Pterospermum lanceaefolium and Peltophorum pterocarpum, the species decline significantly in number towards the semi-evergreen or deciduous dipterocarp forest. Others, like Xylia xylocarpa, Bombax ceiba, Spondias pinnata and Terminalia alata show an opposite reaction of increasing in numbers towards the deciduous dipterocarp forest. The abundance of Lagerstroemia species is greatest in the intermediate semi-evergreen forests. Deciduous dipterocarp forest is associated with areas distant from rivers that receive little drainage, where water is limiting during the dry season, but at no significant elevation. Within this ecological spectrum fall many other habitats including mixed deciduous and bamboo forests, seasonal wetlands, natural grasslands, and shrub lands.
Global recognitions
The Eastern Plains Landscape includes parts of two Global 200 Eco-regions: Annamite range moist forests, and Lower Mekong dry forests. Eco-regions are large areas of relatively uniform climate that harbor a characteristic set of species and ecological communities. WWF identified about 200 of the most threatened of these globally, defined as ‘outstanding representatives of the world’s terrestrial and marine ecosystems”25. Selection has been based on parameters such as species richness, species endemism, high taxonomic uniqueness, unusual ecological or evolutionary phenomena, and keystone habitats. The landscape overlaps with two ‘Last of the Wild’ areas identified in the Indo-Malayan Tropical and Subtropical Dry Broadleaf Forests biome. The Last of the Wild areas were identified by WCS in a global exercise that mapped the extent and intensity of human influence using nine datasets representing four broader categories of land transformation, human density, electrical power infrastructure, and accessibility. These data were used as proxies, and then the ten least affected areas within each biome were selected as being the Last of the Wild26.
The southern, evergreen parts of the Eastern Plains Landscape lie within the South Vietnam / Cambodia Lowlands ‘Endemic Bird Area’, where there are four ‘Important Bird Areas’. Birdlife International has classified Endemic Bird Areas27 by identifying places around the world where two or more endemic and restricted-range species (range below 50,000 km2) overlap, and where Important Bird Areas must do one or more of the following: hold significant numbers of one or more globally threatened species; are one of a set of sites that together hold a suite of restricted-range species or biome-restricted species; have exceptionally large numbers of migratory or congregator species.
The Eastern Plains Landscape falls within Conservational International’s Indo-Burma ‘Hotspot’, indicating the area has high levels of biodiversity and endemism and is under threat. This means that the area holds at least 0.5% of the world’s endemic plant species, has high vertebrate endemism, and is categorized by being under extreme threat. To qualify as being under threat, at least 70% or more of the areas primary vegetation must have been lost28. The analyses identified 25 hotspots around the world that represent disproportionately high levels of biodiversity and are facing the most severe threats.
Species representation
The rich and variable mosaic of habitats in the Eastern Plains Landscape allows for a vast and diverse assemblage of wildlife, many of which find the region as their last remaining stronghold. The landscape holds many endangered species of primates, birds, ungulates, reptiles, and amphibians. Within it are the world’s largest populations of the Yellow-cheeked Crested Gibbon (Nomascus gabriellae) and the Black-shanked Douc (Pygathrix nigripes)29. There are both nationally and regionally important populations of other primate species including Germain’s Silvered Langur (Trachypithecus germaini), Northern Slow Loris (Nycticebus bengalensis), Pygmy Loris (Nycticebus pygmaeus), Stump-tailed Macaque (Macaca arctoides), and Northern Pig-tailed Macaque (Macaca leonine)30.
The Eastern Plains Landscape holds valuable populations of critically endangered bird species. Lomphat Wildlife Sanctuary is the second most important site in the world for the critically endangered White-shouldered ibis (Pseudibis davisoni), with the latest count of 298 birds, second only to the Western Siem Pang Important Bird Area in Stung Treng province31. There are important populations of the critically endangered Red-headed Vulture (Sarcogyps calvus), White-rumped Vulture (Gyps bengalensis), and Giant Ibis (Thaumatibis gigantean). The landscape home to populations of the endangered Green Peafowl (Pavo muticus), White-winged Duck (Asarcornis scutulata), and Masked Finfoot (Heliopais personata).
Following successful fecal deoxyribonucleic acid (DNA) surveys on Asian Elephants (Elephas maximus) by WCS and WWF using capture-mark-recapture techniques, a regionally important elephant population was been confirmed within the Eastern Plains Landscape. WCS conducted a DNA-based study in Seima Protected Forest in 2006 and estimated a population of 116 individuals (±SE = 9.79, 95% CI = [101,139])32. WWF conducted a similar DNA-based study in Phnom Prich Wildlife Sanctuary and Mondulkiri Protected Forest in 2009, which produced a population estimate of 136 (±SE = 18)33 in the sanctuary. A count of 21 individuals was achieved in the protected forest. Results from these surveys indicate a healthy breeding population of Asian Elephants, inevitably moving across the landscape.
Although there is no longer any evidence of tigers living within the Eastern Plains Landscape (the last record was a footprint at Phnom Prich Wildlife Sanctuary in 201034), there are several medium and small cat species in the forests. The vulnerable Marbled Cat (Pardofelis marmorata) and Clouded Leopard (Neofelis nebulosa) are known to exist in the landscape, as is the Leopard (Panthera pardus). The endangered Fishing Cat (Prionailurus viverrinus) is thought to exist in all of the protected areas, as is the Jungle Cat (Felis chaus).
There is a great number of ungulates living across the Eastern Plains Landscape, with all of the protected areas holding populations of the endangered Banteng (Bos javanicus) and Eld’s Deer (Panolia eldii)35, Gaur (Bos gaurus) and Sambar Deer (Rusa unicolor) are listed as vulnerable and are too found across the landscape. In terms of prey species for both wildlife and humans, there are large populations of the more common species such as the Red Muntjac (Muntiacus muntiacus) and Wild Pig (Sus scrofa). Other highly threatened species that can be found within the Eastern Plains Landscape include Dhole (Cuon alpines), Elongated Tortoise (Indotestudo elongate), King Cobra (Ophiophagus hannah), and the Asiatic Soft-shell Turtle (Amyda cartilaginea).
