SARI BUMI KUSUMA

SBK PROVIDES A GLOBALLY SIGNIFICANT MODEL FOR TROPICAL SILVICULTURE

Professor Francis E. “Jack” Putz, University of Florida, USA

In the field of natural forest management in the tropics, Indonesia leads the world and one of the leaders in Indonesia is Sari Bumi Kusuma (SBK) Katingan-Seruyan block in Central Kalimantan. Over my four decades in tropical forestry, I have not yet encountered an operational-scale silvicultural effort like SBK’s.  In South America and Africa, the focus is on reducing the impacts of logging (RIL). SBK employs RIL techniques but then in half of its concession follows selective logging with enrichment planting of seedlings of commercial timber species along cleared lines through the harvested forest.  At the time of my most recent visit in late 2014, SBK had successfully line-planted 49.207 hectares. The company’s total area is 147.600 ha and allocated effective area for two silvicultural systems: TPTJ (60.508 ha) and TPTI (59.098 ha), nature conservation (12.668 ha), and areas used for infrastructure (road, camp buildings), villages, rivers, and seed stands (15.326 ha).

Around the world there are many well-known tropical silvicultural system, but the results of these well publicized experiments with shelterwoods, strip clearcuts, and liberation thinning were not adopted by forest industries. In the few examples where post-logging silvicultural treatments have been applied beyond the confines of experimental plots, the costs were borne by external agencies including ITTO, USAID, FAO, New England Power, and the FACE Foundation—when the subsidies stopped, so did  the silviculture.

In contrast, SBK has so far invested more than $35 million dollars (at $704 per hectare) of its own funds in line-planting as part of a silvicultural system referred to as SILIN (Silvikultur Intensif or TPTJ). Each year, 654 SBK staff clear 3 m-wide planting lines spaced 20 m apart, dig 30 x 30 x 30 cm holes at 5 m intervals along those lines, and plant nursery-grown seedlings in compost inoculated with ectomycorrhizae. After planting, staff members return annually for 3 years to liberate the planted seedlings from lianas and encroaching vegetation. The results are impressive, with seedling survival rates of more than 70% and annual increments in stem diameter of more than 2 cm over the first 10-14 years of data from permanent sample plots maintained by SBK.  At these rates, standing stocks of commercial timber at the end of the planned 25 year rotation will be much greater than before the first timber was harvested from SBK’s forests.  In other words, yields will be much more than sustained!

My most recent visit to SBK was as part of a research workshop sponsored by SBK, Tanjungpura University (UNTAN), and the University of Florida (UF). During an intensive week of field work, data analysis, and manuscript preparation, the fourteen participants (12 Indonesians, 1 Japanese, and 1 American) conducted research on SILIN that should help inform predictions of harvestable timber yields and felling damage. From my perspective as a university professor, the sustained enthusiasm of the group was heart-warming, and the results seem useful.   As usual, our answers to some questions led us to ask others.

As an outsider with great interest in the silvicultural work underway in SBK and other concessions in Indonesia, some of my questions may be naïve, but it’s my job to ask them. I wonder, for example, about the economics of SILIN—is it a financially remunerative approach to tropical forestry? Might it be more profitable if instead of fast-growing merantis (e.g., Shorea leprosula, S. parvifolia, and S. johorensis), SBK planted slower-growing species with higher-valued timber, like bangkirai (S. laevis)? What restrictions on harvesting should be applied at the end of the rotation if there are 100 or more harvestable trees per hectare? Taking them all at once would constitute a clearcut, but which trees should be harvested and how? Why aren’t long-cable yarding techniques being used in Indonesia? I am thinking about yarders fashioned from home-built towers and winches or through modification of excavators—they aren’t difficult to construct and can substantially reduce harvesting costs. A question from beyond the bounds of my of expertise in silviculture is why does SBK have to bear the entire costs of SILIN when for each cubic meter of timber it harvests it contributes to a Reforestation Fund (Dana Reboisasi)?  Similarly, what can be done to increase the sale price of timber from the red meranti group of species?

All management interventions involve tradeoffs---all benefits cannot be simultaneously maximized. For example, intensification of timber stand management may have timber yield benefits but involve biodiversity costs. After all, when you manage for some species you necessarily manage against others. Similarly, clearing of planting lines for enrichment planting involves carbon costs, but presumably those costs compensated for by the benefits of fast-growing planted trees that sequester carbon.

SBK is on the right track and should be better known. Much can be learned from the company’s sustained efforts at sustaining timber yields and protecting the environment. SBK facilitates this sort of learning by hosting silvicultural research workshops, like ours, but also ecologists, wildlife biologists, and social scientists. More broadly, I believe that the survival of Indonesia’s forests and forest industries depends on the success of the sorts of silvicultural practices employed by SBK. This success, in turn, would be fostered by support from the government and civil society.