Prof. Olavi Luukkanen (project leader)
Jarkko Koskela, Riikka Otsamo and Jouni Suoheimo (researchers)

Doctoral dissertations

Koskela, J. 2000. Growth of grass-stage Pinus merkusii seedlings as affected by interaction between structure and function. Univ. Helsinki Tropical Forestry Rep. 20.

Otsamo, R. 2000. Integration of indigenous tree species into fast-growing forest plantations on Imperata grasslannds in Indonesia. Univ. Helsinki Tropical Forestry Rep. 21. Abstract

Suoheimo, J. 1999. Natural regeneration of sal (Shorea robusta) in the Terai region, Nepal. Univ. Helsinki Tropical Forestry Rep. 19.

Background

The vast extent of natural tropical forests and especially the alarmingly increasing area of degraded and deforested land make it essential that, in tropical forestry research, considerably more emphasis than before be put on the ecology of forest degradation and rehabilitation. Several UNCED follow-up processes and the ongoing consolidation of tropical forest policy  in the EU point to this fact. The Finnish development cooperation also aims at integrated development in which forests and forestry are seen as components of the environment, and natural resources are developed and managed in harmony with other land-related activities.

The management of natural forests has generally not yet shown the same positive trends as the planted tree cover in which private initiatives by farmers and enterprises have led to success. The poor performance of tropical silviculture for natural forests was in the past influenced by a general lack of knowledge of forest dynamics. New silvicultural practices should ideally be developed and tested in simple ecosystems. In the tropical forests of Southeast Asia, the natural pine forests present a uniq system for research, and preliminary outlines of their improved management have already been presented by us for the case of Thailand. In the case of Indonesia, with at least 20 million ha of degraded grasslands and a new wave of destruction being caused by forest fires, the question of second-rotation plantation management has become urgent. In our previous work, it was tentatively demonstrated that the local climax tree species could be used for restoration of the natural forest cover after a first rotation of fast-growing  trees. If this result could be further corroborated, this silvicultural approach would have great significance for tropical forest management world-wide.

General study aims

The project focused on (1) rehabilitation and improved management of well-defined types of degraded forests of great importance for environmental conservation and economic development in Southeast Asia, especially by studing the critical ecological factors which limit the silvicultural interventions; (2) providing the follow-up of the forestry development projects supported by Finland in Thailand and Indonesia with research results that are immediately applicable; and (3) maintaining a Finnish research capability in tropical silviculture for the benefit of future development projects and for strengthening of the institutional linkages between forest researchers in Finland and Southeast Asia. In addition, a separate study for improving the silvicultural management of sal (Shorea robusta) forests in Nepal was carried out.

Case studies:

Mixed pine forests in northern Thailand:Growth of grass-stage Pinus merkusii seedlings as affected by interaction between structure and function

Figure 1. Natural pine forests, consisting of Merkus pine (Pinus merkusii) and Khasi pine (P. kesiya), are mainly found in the watershed areas of northern Thailand. Field studies have focused on natural regeneration dynamics of the two pine species under fire-dominating environment. Photo: Jarkko Koskela.

Figure 2. Pines tend to form fire-climax forest communities when exposed to frequent, short-interval surface fires. Photo: Jarkko Koskela.

Figure 3. Effect of defoliation on the growth of the grass stage Merkus pine seedlings was investigated with field experiments in northern Thailand. Photo: Jarkko Koskela

Reforested Imperata grasslands in South Kalimantan, Indonesia: Integration of indigenous tree species into fast-growing forest plantations on Imperata grasslannds in Indonesia

General background

Imperata cylindrica grasslands occur as a fire climax vegetation type in tropical areas where annual fires prevent the natural secondary succession of forest after repeated commercial and illegal logging and subsequent fire-based land-utilization systems. In Indonesia, the area of large continuous grasslands is estimated at 9 million ha. Earlier studies by Finnish and Indonesian researchers have shown that reclamation of Imperata cylindrica grasslands by means of reforestation is possible using fast-growing exotic species, such as Acacia mangium, Gmelina arborea and Paraserianthes falcataria. The present study focused on integration of valuable indigenous timber tree species (e.g. dipterocarps) into grasslands by providing the crucial shade and protection during the seedling phase with the fast-growing nurse crop. Several indigenous species and establishment methods were successfully tested. In addition, the abundance and diversity of natural regeneration of native tree species in fast-growing plantations was studied. Practical implications of the current study include enhancing the production of already scarce timber resources, providing alternative management options for grassland rehabilitation and fastening the restoration of grasslands back to native forests.

Figure 4.. Establishment of fast-growing Acacia mangium plantations is a promising way of reclamation of Imperata cylindrica grasslands in Southeast Asia. Fast-growing plantations on grasslands can provide an alternative for the present unsustainable utilization of natural forests for the growing pulp and paper industry. (A. Otsamo)

Figure 6. Seven-year-old Anisoptera marginata (Dipterocarpaceae) trees planted under a fast-growing Paraserianthes falcataria plantation. The most promising dipterocarp species can reach an annual height growth of 1.5 m a-1. The plantations are characterized by rich understorey growth of secondary shrubs and naturally regenerated native tree species dispersed from the adjacent forest patches.

 

The dissertation consisted of the following publications:

Otsamo, R., Ådjers, G., Hadi, T.S., Kuusipalo, J. and Otsamo, A. 1996. Early performance of 12 shade tolerant tree species interplanted with Paraserianthes falcataria on Imperata cylindrica grassland. Journal of Tropical Forest Science 8(3): 381-394. Abstract.

Otsamo, R., Kurniati, L. and Otsamo, A. 1996. Dipterocarp species on Imperata cylindrica dominated grasslands: a case study from South Kalimantan, Indonesia. In: Suhardi, I. (ed.). Proceeding of seminar on ecology and reforestation of dipterocarp forest in Gadjah Mada University, Yogyakarta, Indonesia, 24-25 January 1996. Faculty of Forestry, Gadjah Mada University and Kansai Environmental Engineering Centre. pp. 147-157.

Otsamo, R. 1998. Removal of Acacia mangium overstorey increased growth of underplanted Anisoptera marginata (Dipterocarpaceae) on an Imperata cylindrica grassland site in South Kalimantan, Indonesia. New Forests 16: 71-80. Abstract.

Otsamo, R. 1998. Effect of nurse tree species on early growth of Anisoptera marginata Korth. (Dipterocarpaceae) on an Imperata cylindrica (L.) Beauv. grassland site in South Kalimantan, Indonesia. Forest Ecology and Management 105: 303-311. Abstract.

Otsamo, R. and Kurniati, L. 1999. Early performance of ten timber species planted under Acacia mangium plantation on an Imperata cylindrica grassland site in South Kalimantan, Indonesia. International Tree Crops Journal 10(2): 131-144. Abstract.

Otsamo, R. 2000. Early development of three planted indigenous tree species and natural understorey vegetation in artificial gaps in an Acacia mangium stand on an Imperata cylindrica grassland site in South Kalimantan, Indonesia. New Forests 19: 51-68. Abstract.

Otsamo, R. 2000. Secondary forest regeneration under fast-growing forest plantations on degraded Imperata cylindrica grasslands. New Forests 19: 69-93. Abstract.

Other related publications:

Otsamo, R. 1996. Integrating indigenous tree species in forest plantations on Imperata cylindrica grasslands - results from Riam Kiwa, South Kalimantan. In: Otsamo, A., Kuusipalo, J. and Jaskari, H. (eds.). Reforestation: meeting the future industrial wood demand. Proceedings of a seminar held in Jakarta 30 April and 1 May 1996. Reforestation and Tropical Forest Management Project (ATA-267). Ministry of Forestry, Forestry Research and Development Agency. Enso Forest Development Ltd, FINNIDA. Jakarta. pp. 87-95.

Otsamo, R., Ådjers, G., Kuusipalo, J., Otsamo, A., Susilo, N. and Tuomela, K. 1996. Effect of nursery practices on seed germination of selected dipterocarp species. Journal of Tropical Forest Science 9(1): 23-34. Abstract.

Otsamo, R., Otsamo, A. and Ådjers, G. 1996. Reforestation experiences with dipterocarp spieces on grassland. In: Schulte, A. and Schöne, D. (eds.). Dipterocarp Forest Ecosystems - Towards Sustainable Management. World Scientific, Singapore. pp. 464-477.

Otsamo, R. and Otsamo, A. 1999. Early development of seedlings of six tree species after a rotation of Acacia mangium on an Imperata cylindrica grassland site in South Kalimantan, Indonesia. International Tree Crops Journal 10(2): 145-160. Abstract.