Riau plantation forests
Riau plantation forests, primarily located in the Riau Province of Sumatra, Indonesia, are mainly comprised of Acacia species, which are cultivated for their wood, supporting sustainable pulp, paper, and wood processing industries. The Indonesian government initiated extensive forest plantation development in 1985, aiming to utilize approximately 22.2 million acres of degraded land. These plantations are designed to provide raw materials for various industries, improve local environmental quality, create job opportunities, and enhance community welfare. However, Riau has faced significant deforestation, with millions of acres lost to illegal palm oil plantation expansions, particularly in the 2020s. Acacia mangium and Acacia crassicarpa are the primary species cultivated, known for their rapid growth, favorable wood characteristics, and ability to thrive on marginal lands. The sustainability of these plantations is influenced by management practices and environmental factors; however, issues like declining productivity and the impact of monoculture on biodiversity raise concerns. Despite challenges, Acacia forests may provide certain ecological benefits compared to previous land uses, such as Imperata grassland, fostering diverse soil fauna and fungi. The ongoing deforestation crisis highlights the need for increased oversight and balance between economic development and environmental conservation.
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Riau plantation forests
- Category: Forest Biomes
- Geographic Location: Indonesia
- Summary: These forest plantations of Acacia spp. provide raw materials for sustainable pulp, paper, and wood processing industries.
The government of Indonesia began aggressive support of forest plantation development in 1985, specifically targeting about 22.2 million acres (9 million hectares) of unproductive or degraded land around the archipelago. Forest plantation aims under this program were to provide raw materials for the timber and fiber (pulp and paper) industries, to improve the quality of local and regional environments, to provide job opportunities, and otherwise enhance human welfare in the localities.
Riau, a province in east-central Sumatra Island, has the largest forest plantation in Indonesia, with Acacia as the dominant genus. In 2010, the total forest area in Riau province was about 21.3 million acres (8.6 million hectares), including critical lands of some 3.7 million acres (1.5 million hectares). However, in the 2020s, Riau lost millions of acres of forests and plantation forests to deforestation for palm oil plantations. About half of these plantations were established illegally.
Acacia was selected as the featured tree genus in forest plantations here because of its ability to grow rapidly on marginal lands, its ample production of seeds, relatively simple silviculture techniques, and its multi-use wood that is suitable for pulp and paper manufacture. Two species of Acacia are commonly planted on different soil types. For example, Acacia mangium is commonly planted on mineral soil of lowland forest, while A. crassicarpa can be planted on peat swamp area.
The wood of A. mangium or A. crassicarpa has suitable physical characteristics for pulp and paper industries. Both species produce long fibers, with favorable balances of cellulose and lignin, along with other characteristics that serve the end product well. For construction timber, A. mangium wood is better suited, with end-uses comprising plywood, furniture, light construction, handicrafts, utensils, and flooring.
Acacia is commonly planted as an even-aged monoculture system with planting space of forty-thre to ninety-seven square feet (four to nine square meters) under intensive, if straightforward, silviculture practices. In the early development of forest plantation, Acacia mangium was planted on degraded land and Imperata grassland, so named for the genus of tough, opportunistic grasses that colonize fire-denuded or otherwise cleared areas. Seedlings of A. mangium are produced from generative and vegetative propagation. The trees can reach a height of 115 feet (35 meters), and a diameter at breast height of 20 inches (50 centimeters).
The life cycle of Acacia for pulp and paper is about five to six years, and more than eight years for construction timber. The biomass volume output, depending on the quality of seedlings, runs to about eight to seventeen cubic yards per acre (twenty to forty cubic meters per hectare) per year. This inherently strong rate of growth is accentuated by the tropical climate these forests enjoy.
Environmental Issues
The sustainability of these forest plantations depends on site conditions, management intensity, and various impacts on the soil of the local ecosystem. The productivity of the Riau forest plantations was recorded as declining by the third generation. Improving seedling quality and returning mulched, unused biomass such as bark, twigs, and leaves to the ground, along with phosphate fertilizer, have been the main responses of the industry. This is not necessarily positive for other species in the biome.
However, there are some indications that Acacia forest plantations positively impact biodiversity compared with the previous land use before and during its manifestation as Imperata grassland. More than one dozen species of Acacia seedlings actually get planted in the average plantation due to inexact nursery practices. Among other biota, micro-flora, particularly mushrooms, are strongly represented here. One study showed fifty-five species of fungi from four families in an uneven but pervasive density across the research area.
Invertebrate soil fauna in the Acacia plantations tend to consist of reasonably dense populations of such featured types as the classes Diplopoda (millipedes) and Arachnida (spiders and mites), orders Hymenoptera (ants, wasps, bees, and sawflies) and Coleoptera (beetles), and families Blattidae (cockroaches) and Lumbricidae (earthworms).
Important in considering the net value of the forest plantation program in Riau is the fact that launching and maintaining these forests has occurred during an historical period of extremely fast deforestation of this region. At its inception in 1985, Riau forest cover had declined by 25 percent, and by the 2020s, the forest cover had plummeted by 85 percent. While some of this deforestation resulted from expanding logging plantations, most occurred because of palm oil plantation expansion, nearly half of which were illegal. Creating palm oil plantations involves clearing peatlands, which release carbon into the atmosphere. These illegal plantations accounted for about half of Indonesia's illicit oil palm facilities, covering 2.52 million hectares (6.23 million acres). Experts called on the Indonesian government to increase transparency and limit the expansion of these illegal operations. However, many conservation experts noted that these plantations would likely continue to expand as long as the global demand for palm oil remained high.
Bibliography
Arisman, H., and E. Haridyanto. “Acacia Mangium: A Historical Perspective on its Cultivation.” In K. Potter, et al, eds., Heart Rot and Root Rot in Tropical Acacia Plantations: Australian Centre for International Agricultural Research, 2006.
Hardiyanto, E.B., et al. “Early Result of Site Management in Acacia Mangium Plantation at PT Musi Hutan Persada, South Sumatra, Indonesia.” In E. K. S. Nambiar, et al., Site Management and Productivity in Tropical Plantation Forests. Center for International Forestry Research, 2004.
Jong, Hans N. "Report: Half of Plantations in Indonesia’s Palm Oil Heartland are Illegal." Mongabay, 13 Oct. 2023, news.mongabay.com/2023/10/report-half-of-plantations-in-indonesias-palm-oil-heartland-are-illegal. Accessed 26 Dec. 2024.
Juniyanti, Lila, and Rospita Odorlina Pilianna Situmorang. “What Causes Deforestation and Land Cover Change in Riau Province, Indonesia.” Forest Policy and Economics, vol. 153, 2023, doi:10.1016/j.forpol.2023.102999. Accessed 26 Dec. 2024.
Numato, Izaya, et al. "Deforestation Plantation-Related Land Cover Dynamics and Oil Palm Age-Structure Change during 1990-2020 in Riau Province India." Environmental Research, 9 Jan. 2022, doi:10.1088/1748-9326/ac8a61. Accessed 26 Dec. 2024.
Sudarmalik, Mindawati N. Site Characteristics of First and Second Rotation Acacia Crassicarpa Stands in Riau.(Proceedings National Seminar of Indonesian Wood Research Society XI.). Faculty of Agriculture of Palangka Raya University, 2008.