Figure 2.6. Dense evergreen forest on steep slopes (east of Nam Beng).

Figure 2.7. Degraded form of forest as a result of shifting cultivation practices.

The spatial distribution of ten land use/land cover categories based on the interpretation of the SPOT satellite data was enumerated in Table 2.2. It shows that approximately 32% of the chosen study area is considered to be covered by dense evergreen dominated forest, while 42% of the total area are found subject to human exploitation under different form of cultivation practices from lowland to upland. An estimated 20% was attributed to the places blanketed by open woodlands or degraded type of forest (see Figure 2.8).

Table 2.2. Areal extent of distribution of the classified land use/land cover categories

(in hectare).

Narrow valleys offer small area of about 921 ha primarily allotted to rice cultivation. Hence, a total area of 48,000 ha has been presently utilized for upland cultivation at various topographic gradient.

2.7.4 Map Integration through GIS

Combined available ancillary data with the generated land use/land cover of the study area using GIS render additional dimension in terms of analyzing the resource variables on it. Relevant results on its spatial aspect have been highlighted below.

Spatial interactions about the frequency and location of villages among the identified land use/land cover types (1992 SPOT data) were established. The 1983, 1:100,000 topographic map of Lao P.D.R. provided the location and different categories of village according to the number of houses such as big, small and abandoned villages. Villages composed of 15 to 19 houses was classified as small village and more than 20 houses up to 155 falls under bigger division as indicated on the topographic map sheets covering the whole study area. However, isolated villages with house composition of less than five were not included in this investigation.

Major findings indicated that large number of big villages are generally located on classified scrubland (Fb), while 20% are positioned in shifting cultivated area. Only one big village was found inside a burnt cultivation plot in the upland (Sc11). A different observation was noted for small villages wherein they are largely situated in areas covered by close forests. Neither of the 21 abandoned villages fall in any shifting cultivation area nor paddy field.

Likewise the proximity of the villages according to the existing land use/land cover type that surround them was also analyzed. A 1 kilometer buffer for every village type was demarcated purposely to identify the influence of their presence on the type of land use/land cover within this range. In general, disregarding the village category, scrubland where trees and bushes regarded as the dominant cover (Fb) followed by thick forest cover (Fc) tends to be the common land use/land cover type within a distance of 1000 meter away from the village. The nearness to the site where wood for much needed construction materials, fuelwood and the water supply became the prominent reason for such kind of distribution pattern. About 18% of the one kilometer buffered area is said to be covered by shifting cultivation area. This also illustrates that upland cultivators normally travelled more than one kilometer distance away from their houses in order to reach and search for their respective agricultural plots.

Considering the village category, large communities appeared to cover large area for scrubland similar to abandoned villages. However, permanent form of cultivation such as paddy area is obviously absent in a deserted community. The presence of plots where soil is exposed or recently burnt spot shows that human activity is still going-on despite the absence of their village within that area. Small group of houses requires both the ecological and economic support from the forest, thus, maintaining their presence adjacent to a tree-covered site. Their respective upland plots are somewhat located away from their houses and one kilometer distance is not yet far for them to search and utilize a certain piece of land on the hills and mountains. Table 2.3 provides the land use/land cover type distribution on a kilometer radius from various village categories.

Using an elevation map with 100 m contour interval, the study area was found lying at a minimum of 800 m and reaching as high as 1100 m. The distribution of interpreted forest types and various stages of shifting cultivation on changing elevation gradient identified do not reveal any distinct spatial pattern. The decreasing human activity is apparently related to the increasing elevation. Only a few patches of cultivation plots were found situated in the range of 1000 - 1100 m. On the other hand, the presence of major forest cover distributed at the middle elevation (800 - 1000 m) bears a strong threat towards human exploitation where they share a common altitudinal preference. Table 2.4 enumerates major land use/land cover types in various elevation categories.

Table 2.3. One kilometer radius distribution of major land use/land cover categories in different village type (in hectare).

Table 2.4. Major land use/land cover types over different elevation gradient (in hectare).

2.8 SUMMARY AND CONCLUSIONS

The analysis of time series NOAA AVHRR satellite data of Lao P.D.R. at the macro scale identified Oudomxay province of northern Laos as one of the "hot spot" area for further investigation. Available national reports also emphasized that among the northern provinces of the country, Oudomxay exhibits one of the highest hectarage covered by slash and burn cultivation and with a fastest growing population.

An area having a dimension of 60 x 60 km was investigated using a high spatial resolution SPOT data acquired on 26 March 1992. Various stages of shifting cultivation practices from land preparation (burnt and exposed soil) up to fallow fields covered by thick bushes were identified both in the satellite image and on the ground. Shifting cultivation plot size ranges from 2 to 650 ha were distributed in the watershed of two major river systems, Nam Tha and Nam Beng. Proximity to these rivers and a road along the Nam Beng that connects Xai and Pak Beng districts provided a strong market pull for small and large villages to be attached with these natural features and available infrastructure in exchanging their goods and services.

Satellite image interpretation approximates that 42% of the whole study area is subjected to human exploitation under various form of agricultural practices from lowland to upland, and the remaining 32% are still covered by evergreen dominated type of forest. Narrow valleys offer small area allotted for paddy cultivation.

Combining the location of the village with GIS database suggests that their influence on their surrounding ecosystem in utilizing and looking for new agricultural plots creeps far beyond their backyard. The presence of plots where soil is exposed or recently burnt site shows that human activity is still in effect despite the absence or remote distances of their villages with respect to that area. The rolling topography in a middle elevation gradient harbors the large proportion of remaining forest in the watershed where upland cultivators showed their strong preference to satisfy the existing demand for available and fertile grounds.

The intensity of occupation of some areas, and the considerable size of the agricultural plots, indicated a high pressure on the land and low yields per hectare. This combination most certainly will cause a long-term decline in the productive potential of the uplands for both agriculture and forestry.

Though there was no comprehensive and large scale drastic land transformation found in the multi-temporal analysis of 1 km resolution AVHHR data for LAO P.D.R., the sporadic spectral variations observed in the northern part of the country leads to a detailed and timely investigation of its resources. The national assessment of the land cover of the country while giving attention to an area where major land cover transformation is occurring render a direct information link and challenge to generate the appropriate and punctual actions for the identified agent of land degradation.
 

REFERENCES

IUCN (1988) Technical Report on Shifting Cultivation in Laos. Gland, Switzerland, December 1988.

Lao P.D.R., Ministry of Agriculture and Forestry, (1992). Forestry Policy in Lao P.D.R. Regional Expert Consultation on Forestry Policy Developments in Asia and the Pacific. FAO-RAPA, Bangkok, Thailand. 5 - 9 October 1992.

Lao P.D.R., Ministry of Agriculture and Forestry, (1990). Lao People's Democratic Republic Tropical Forestry Action Plan (First Phase), Executive Summary. Vientiane, Lao P.D.R., August 1990.

Lao P.D.R., Ministry of Economy Planning and Finance State Statistical Centre, 1990. Basic Statistics about the Socio-economic Development in the Lao P.D.R. for 15 years (1975-1990). Vientiane. 1991.

Mekong Secretariat (1993) Action Plan for Water Resources Development and Management in the Nam Beng Basin, Laos (Project Proposal). Bangkok, September 1993.

Phanivilay, K. (1990) Forest and Soil Conservation in Laos. Regional Community Forestry Training Center. Bangkok, Thailand, December 1990.

Phanthalangsy, V. (1991) Agroforestry Development in Luang Prabang Province, Lao P.D.R. Regional Community Forestry Training Center. Bangkok, Thailand, December 1991.

UNDP, 1991. Fact Finding Report of the Environment of Lao People's Democratic Republic. Revised Second Draft. UNDP, Vientiane, Lao P.D.R., August 1991.