Review of forestry site studies in South Kalimantan

Forest plantation growth in Indonesia is influenced primarily by rainfall, and in particular the distribution rather than the total amount. Where the dry season is short (less than three months) there is less of a requirement for deep soils to act as a reservoir during the tree’s time of need. When there is a marked dry season, (four to five ‘dry’ months with a monthly total less than 100mm), the role of the soil to compensate becomes more critical. Accurate rainfall information is thus vital. With the substantial variations that are experienced in annual rainfall in Indonesia, it is important to use rainfall data that has been collected over a 20-year period. Soils are best assessed during that season when they are at their most limiting to tree growth. Therefore, those soils that, for instance, suffer from impeded water drainage, are best assessed during the height of the wet season. Alternatively, those soils that become hard and develop strong structure that may inhibit rooting, are best assessed during the dry season.

The relatively good tree going conditions in Indonesia, relative to drier countries such as Australia and South Africa, make the main focus of any site potential survey the matching of different species to particular sites, rather than the determination of whether or not trees should be planted. The previous land use history is important to any site survey. Sites that have been under alang-alang behave differently to those used in agricultural fields, which in turn are different to those that have been converted directly from forest to HTI
The remaining HTI plantations included in this study fall into the Southern coastal plains subregion. Within this subregion, the Jerong-Telakai coastal plain includes the Pleihari and Kintap plantations, and the Laut-Sebuku islands include the Pulau Laut plantations.
The RePPProt report is designed for large scale planning and with the paucity of soils information available, is not designed or able to provide the detailed soils and site information required for this study. Soils types for fast growing tree plantations and their distribution in southeastern South Kalimantan, Turvey and Ruhiyat (1990). This report was designed to locate a large expanse of open land in the southeast of the province that could be developed for a plantation project to feed a pulp and paper mill. Five areas were targeted and included the Riam Kiwa area in the vicinity of the Riam Kanan reservoir, a large tract of coastal land running from Jerong in the south to Pagatan in the north, and the southern part of Pulau Laut. Ten soil types were identified and rated in terms of their site potential. In was concluded that eight percent of the area was highly suitable for tree plantations, 13 percent moderately high, 49 percent of moderate to low suitability and 30 percent as very low suitability. The largest area of soils considered suitable for plantation development were the southern portion of Pulau Laut. An assessment of the soils and nutrient status of the trial plantations at Riam Kiwa, Simpson (1992). This report was part of the Indonesian-Finland project investigating the rehabilitation of degraded (alang-alang) grasslands using fast growing plantations in the Riam Kiwa area. Simpson found no reliable soils literature for the area, and after an initial assessment concluded that the soils were generally deeply weathered, heavy textured, acid, well drained and well structured with little textural variation between sites. The three major soil groups (red and yellow podzolics, and alluvials) were not obviously related to plantation productivity. Soil chemical data was obtained from limited samples and indicated moderate fertility levels. Simpson also considered that plantation productivity might be related to total potassium levels, as was indicated by limited foliar analysis of Acacia mangium. Simpson advocated that further fertilizer trials should be established to more adequately investigate the nutritional needs of the different species on the different sites at Riam Kiwa. He considered that while soils and foliar chemical data provide good background information, only on-the-spot fertiliser trials allow for the determination of optimal amounts of fertiliser and the corresponding growth responses
South Kalimantan site productivity study: location of soil profiles and growth plots
1. The Marabahan site is a woodlot scheme on the Barito river floodplains approximately 15 km north-west of Banjarmasin. Young stands of Paraserianthes falcataria, both less than three years old, were assessed on sites inundated by flood waters in the wet season.
2. Kirana Rimba lies north of Riam Kiwa plantations in the undulating foothills of the Gunung Meratus. Belonging to PT Hendratna, it consists mainly of Paraserianthes falcataria and Gmelina stands planted around the mid-90s. Altitudes are close to 200m which are regarded as relatively high for this province.
3. The BTR-Riam Kiwa plantations include the substantial trials established under the FINNIDA project between 1989 and 1995. A large number of species and provenances were trialed in a scheme which was partly responsible for the wide-scale adoption of Acacia mangium as a commercial species. Altitudes ranged from 100 to 120m.
4. The Inhutani III plantations at Riam Kiwa lie between Kirana Rimba and the above-mentioned BTR-Riam Kiwa plantings. These plantations are located on the rolling foothills of the Meratus range at altitudes between 100 and 150m. Two plots were laid out in young teak plantings.
5. The Inhutani III plantations at Pleihari are located on the low altitude plains (5 to 20m) in the south of the province. Large scale trial plantings of a variety of species has occurred since the early 1990s. These plantings are of interest as they include Eucalyptus species.
6. The substantial plantations belonging to PT Menara Hutan Buana at Kintap were established around 1995 and are essentially Acacia mangium from local Subanjerji seed sources. Altitude is low (40 to 50m) and topography gentle.
7. The Inhutani II plantations on Pulau Laut are situated on the large island in the south-east of the province. Altitude is less than 50m and topography gentle. A wide variety of species has been planted including a series of well established trials established by the Shell organisation in 1992.