3. FOREST RESOURCES

The distribution of land use and land cover as estimated in 1993 from Landsat remote sensing data with visual interpretation by the Ministry of Agriculture and the Remote Sensing Mapping Unit of the Mekong Secretariat, as well as the result of estimation from the computer-based interpretation (digital processing) using Landsat TM by Japan Forest Technical Association in its project entitled "Information System Development Project for the Management of Tropical Forest" of the fiscal years 1993-1995, both indicate the significance of forests in Cambodia's overall environment, fully 60 percent and 63 percent respectively of the country is covered by forests. This is a higher percentage than any country in the sub-region and among the highest of some countries in the world. The assessment based on the above results of the Mekong Secretariat shows the most significant land cover changes in the last 20 years: the 11.2 percent reduction in total forest cover (forest land and edaphic forest combined), the 113.9 percent increase in shrubland and the 26.0 percent in agricultural land (rice fields and other crops combined).

Table 1.1 - Change in Land Cover between 1973 and 1993 (Area in Hectares)

	1973	1993	Change	Annual Change
Urban	14,700	4,500	-10,200	-3.5%
Rice fields	2,521,000	2,639,000	118,000	0.2%
Other crops	582,000	1,275,400	693,400	6.0%
Dry land forests	11,678,600	10,568,600	-1,110,000	-0.5%
Edaphic forests	1,032,500	715,600	-316,900	-1.5%
Shrublands	1,056,900	2,260,600	1,203,700	5.7%
Abandoned lands	786,300	278,700	-507,600	-3.2%
Water surface	481,500	411,100	-70,400	-0.7%
Total	18,153,500	18,153,500	0	-

Source: Land Use Mapping Statistics

The most significant result of land use practices of the last 20 years, such as commercial logging, shifting cultivation and wood harvesting for fuelwood and charcoal production, has been a net loss of some 1,110,000 hectares of dryland forest and 316,900 hectares of edaphic forest. In percentage terms the reduction in forest area over the last 20 years has been about 0.5 percent per year which is one-half the 1.0 percent per year average of countries of the sub-region during the same period. The increase in shrublands suggests that it is the primary form of land cover to succeed forests after clearance.

The most up-to-date forest resource information for Cambodia is the 1994 Land Cover Atlas prepared by the Mekong Secretariat, and Forest Register 1995 by JAFTA (Japan Forest Technical Association) (see Annex 1). Although more recent changes may have occurred and have been reported, especially along the western border with Thailand, no data are available to evaluate these reports. The total forest area of 11.3 million hectares is divided into 4.8 million hectares of evergreen forest. 4,3 million hectares of deciduous forest. 1 million hectares of mixed forest. 0.5 million hectares of secondary forest and 0.7 million hectares of edaphic forest (see table 1.2).

Changes in forest cover that have occurred over the last 20 years are shown in Table 1.2 by forest type. Some forest types, such as the edaphic, are in particular danger. These include mangrove areas along the Gulf of Siam and flooded forest around the Tonle Sap Lake which decreased at a rate of 1.53 percent per year between 1973-1993. Once again, while there have been reports that changes in land cover have affected hydrologic conditions in the Tonle Sap and its surroundings, there are no data or detailed scientific analyses which can substantiate these claims. The hydrologic role of forests, however, is well established and it is reasonable to expect that major changes in forest area should have significant impact on stream flows and aquatic life.

Table 1.2 - Area of Forest by Type and Change 1973-1993 (hectares)

	1973	1993	Change	Annual Change
Dry land forest
Evergreen	6,876,400	4,763,300	-2,113,100	-1.5%
Coniferous	9,300	9,800	500	0.3%
Deciduous	4,792,900	4,301,200	-491,700	-0.5%
(Mixed			977,300	977,300)
(Secondary			571,000	571,000)
Subtotal	11,678,600	10,568,600	-1,110,000	-0.5%
Edaphic forest
Flooded	937,900	370,700	-567,200	-3.0%
(Flooded Secondary			259,800	259,800)
Mangrove	94,600	85,100	-9,500	-0.5%
Subtotal	1,032,500	715,600	-316,900	-1.5%
Total	12,711,100	11,284,200	-1,426,900	-0.6%

Note: Changes in classification introduced in the 1993 study are indicated in italic for account for a portion of the charges suggested in the original classifications.
Source: Mekong Secretariat

Box 1 - Major Forest Types in Cambodia Dry land forests: Include evergreen, coniferous, deciduous. mixed and secondary forests. Evergreen forest: Multi-storey forest consisting of more than 80% of evergreen species. The main characteristic species are Dipterocarpus dyeri, D. corbatus, D. Alatus, Anisoptera cochinchinensis, Hopea adorata, H. pierrei, Roherea vulgaris, Syzygium spp. Coniferous forest: Refers to Pines forest (mainly in Kirirom area). Deciduous forest: Dry deciduous Dipterocarp forest. Most characteristic species are forest resistant and have thick hark, such as Dipterocarpus intricatus, D. obtusifolius, Shorea obtusa, Terminalia tomentosa, etc. Mixed forest: Forests of deciduous and evergreen species, where deciduous species represent more than 50 percent of the stand. Secondary forest: Refers to open forest with growth mostly after shifting cultivation. Edaphic Forests: Include flooded, flooded secondary and mangrove forests. Flooded forest: Refers to flooded forest around the Tonle Sap Lake. Flooded secondary forest: Refers to flooded secondary forest with open canopy and regrowth after cultivation or cutting. Mangrove forest: Refers to mangrove forest (on tidal saline water) and rear mangrove forest.

At the provincial level, as shown in Annex 1, forest distribution is quite varied. Forests in the west are mainly evergreen and the north-east is largely covered by deciduous forests. The southern and central parts of the country have less important forest cover and face a shortage of wood, in particular for fuelwood. Weak infrastructure docs not permit raw material transport from the forest area of the north-east and the west where wood potential is high; as a result the remaining woodlands of the south are under heavy pressure to supply the local population. Available potential data provide only forest area. Detailed estimates on changes in forest volume are not available, making it impossible to provide estimates of forest degradation by province and its cause. However, because population density and transport costs are such important factors, it is likely that logging has had its major impact along the international borders of Cambodia and in the coastal province of the Koh Kong; that fuel collection has been most important along the outskirts of the forest in the central part of the country; and that shifting cultivation has been most important in the north-east provinces.

Properly managed, logging is not necessarily detrimental or degrading, but uncontrolled logging can be harmful, and aerial photographs of some areas do show a high proportion of trees removed. Most logging in Cambodia is conducted as selective cutting, rather than clear cutting because it is more profitable to exploit the best timber within reach rather than to attempt complete removal. Ground checks seem to indicate that only large timber is being transported and this concurs with the satellite image patterns which do not reveal logging as a major source of change in forest area and aerial photographs which show trails cut for logging purposes and timber extraction.

While the removal of large trees from the evergreen forest may be less damaging to the environment, removal of the same emergent trees from the open deciduous forest could seriously change the vegetative composition and rapidly degrade that type of forest, because of its very low stock volume. Furthermore, uncontrolled fires are common occurrences in the deciduous forest areas, and imagery acquired after January is often not usable, because of the fire scars.