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Vegetation Structure Of Orangutan Habitat In Kerangas Forest Within An Industrial Timber Plantation In Central Kalimantan
Corresponding Author(s) : Yaya Rayadin
Sustainability Science and Resources, Vol. 10 (2026): Sustainable Science and Resources
Abstract
The persistence of orangutan populations within industrial landscapes depends heavily on the availability of natural forest patches that provide essential resources for foraging, nesting, and other daily activities. PT Industrial Forest Plantation (PT IFP) is an industrial timber concession in Central Kalimantan that lies within the distribution range of the Bornean orangutan (Pongo pygmaeus wurmbii) and is characterized by a kerangas forest (or heath forest) ecosystem. This study aimed to evaluate the quality of orangutan habitat within PT IFP by analyzing vegetation structure and composition, with particular emphasis on the availability of food and nesting tree species. Vegetation surveys were conducted in three High Conservation Value Areas (HCVAs)—Gawing, Mangkutup, and Muruy—using a line-transect plot method. Five vegetation plots measuring 20 × 100 m were established across the study sites, and all trees with a diameter at breast height (DBH) ≥ 10 cm were recorded. A total of 87 tree species belonging to 29 families were identified, with the highest species richness observed in Muruy (64 species from 24 families), followed by Mangkutup (41 species from 22 families) and Gawing (36 species from 18 families). Importance Value Index (IVI) analysis revealed that species from the families Dipterocarpaceae and Myrtaceae dominated the stand structure across all sites. Sorensen Similarity Index values among the three HCVAs ranged from 44.0% to 53.33%, indicating moderate similarity in species composition. Of the total tree species recorded, 49.43% were classified as orangutan food trees and 60.92% as nesting trees, demonstrating that kerangas forests within the concession provide key resources required by orangutans. These findings emphasize the ecological importance of kerangas forests embedded within industrial timber landscapes and highlight their critical role in supporting the persistence of Bornean orangutan populations through habitat-based conservation management.
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- Ancrenaz M, Gumal M, Marshall AJ, Meijaard E, Wich SA & Husson S. Pongo pygmaeus. The IUCN Red List of Threatened Species 2016: E.T17975A123809220. https://doi.org/10.2305/IUCN.UK.2016-1.RLTS.T17975A17966347.en.
- Ancrenaz M, Oram F, Nardiyono N, Silmi M, Jopony MEM, Voigt M, Seaman DJI, Sherman J, Lackman I, Traeholt C, Wich SA, Santika T, Struebig MJ, Meijaard E (2021), Importance of Small Forest Fragments in Agricultural Landscapes for Maintaining Orangutan Metapopulations. Front For Glob Change 4: 560944. https://doi.org/10.3389/ffgc.2021.560944
- Areendran G, Sahana M, Raj K, Kumar R, Sivadas A, Kumar A, Deb S, Gupta VD (2020), A systematic review on high conservation value assessment (HCVs): Challenges and framework for future research on conservation strategy. Science of The Total Environment 709: 135425. https://doi.org/10.1016/j.scitotenv.2019.135425
- Alikodra, HS (2020), Konservasi Satwa Liar dan Ekosistemnya. Bogor: IPB Press.
- Anirudh NB, Van Veen FJF, Ripoll-Capilla B, Buckley BJW, Erb WM, Niun MA, Maimunah S, Makur KP, Armadiyanto, Estrada E, Boyd NS, Cheyne SM, Santiano Namaskari N, Husson SJ, Randi A, Seaman DJI, Deere NJ, Supriatna J, Struebig MJ, Harrison ME (2025), Lowland heath forests of Indonesian Borneo: ecological value and conservation challenges. Journal of Tropical Ecology 41: e19.
- https://doi.org/10.1017/S0266467425100084
- Ashton P (2014), On the forests of tropical Asia: lest the memory fade. Kew publishing. Budiana D (2021), Analisis Struktur Vegetasi Hutan Rawa Gambut dan Hubungannya dengan
- Habitat Orangutan. Jurnal Ekologi Tropis 25(N3): 23-134.
- Delgado Jr RA and Van Schaik CP (2000), The behavioral ecology and conservation of the
- orangutan (Pongo pygmaeus): A tale of two islands. Evolutionary Anthropology: Issues,
- News, and Reviews: Issues, News, and Reviews, 9(5): 201-218.
- Din H, Metali F, Sukri RS (2015), Tree Diversity and Community Composition of the Tutong
- White Sands, Brunei Darussalam: A Rare Tropical Heath Forest Ecosystem. International
- Journal of Ecology 2015: 1–10. https://doi.org/10.1155/2015/807876
- Galdikas BMF (1978), Adaptasi orangutan di Suaka Tanjung Putting Kalimantan Tengah.
- Jakarta: UI Press.
- Galdikas BMF (1982), Orang utans as seed dispersers at Tanjung Puting, Sentral Kalimantan:
- implication for conservation. The Hague: Dr W Junk Publishers.
- HCV Resource Network (1999), Available at: https://www.hcvnetwork.org [accessed 6
- November 2025].
- Hilwan I (2015), Karakteristik Biofisik Pada Berbagai Kondisi Hutan Kerangas di Kabupaten Belitung Timur, Provinsi Kepulauan Bangka Belitung. Jurnal Silvikultur Tropika 06(1): 59-65.
- Husson SJ, Wich SA, Marshall AJ, Dennis RD, Ancrenaz M, Brassey R, Gumal M, Hearn AJ, Meijaard E, Simorangkir T, Singleton I (2009), Orangutan distribution, density, abundance and impacts of disturbance. In: Wich SA, Atmoko SSU, Setia TM, van Schaik CP (ed) Orangutans: Geographic Variation in Behavioral Ecology and Conservation. New York: Oxford University Press. pp. 77-96.
- Ikbal IM, Din HHM, Tuah WH, Jaafar SM, Ahmad N, Sukri RS (2023), Review: Diversity, structure, and community composition of Bornean heath forest with a focus on Brunei Darussalam. Biodiversitas 24(5): 2814-2829. https://doi.org/10.13057/biodiv/d240535
- Krebs CJ (1985), Ecology The Experimental Analysis of Distribution and Abundance. New York: Harper and Row Distribution.
- Lohbeck M, Poorter L, Martínez‐Ramos M, Rodriguez‐Velázquez J, Van Breugel M, Bongers F (2014), Changing drivers of species dominance during tropical forest succession. Functional Ecology 28: 1052–1058. https://doi.org/10.1111/1365-2435.12240
- Maimunah S, Capilla B, Armadiyanto, Harrison M (2019) Tree diversity and forest composition of a Bornean heath forest, Indonesia. IOP Conf Ser: Earth Environ Sci 270:012028 https://doi.org/10.1088/1755-1315/270/1/012028
- Meijaard E, Albar G, Nardiyono, Rayadin Y, Ancrenaz M, Spehar S (2010), Unexpected Ecological Resilience in Bornean Orangutans and Implications for Pulp and Paper Plantation Management. PLoS ONE 5:e12813. https://doi.org/10.1371/journal.pone.0012813
- Mitchell RJ, Auld MHD, Le Duc MG, Robert MH (2000), Ecosystem stability and resilience: a review of their relevance for the conservation management of lowland heaths. Perspectives in Plant Ecology, Evolution and Systematics 3: 142–160. https://doi.org/10.1078/1433-8319-00009
- Mukhlisi and Gunawan W (2019), Karakteristik Vegetasi Habitat Orangutan (Pongo pygmaeus morio) di PT Kaltim Prima Coal Kalimantan Timur. Jurnal Biologi Al-Kauniyah 12(1): 63-72.
- Mueller-Dumbois D, Ellenberg H (1974), Aims and Methods of Vegetation of Ecology. New York: Willey and Sons Inc.
- Nowak MG, Rianti P, Wich SA, Meijaard E & Fredriksson G (2017), Pongo tapanuliensis. The IUCN Red List of Threatened Species 2017: E.T120588639A120588662. https://doi.org/10.2305/IUCN.UK.2017-3.RLTS.T120588639A120588662.en.
- Prasetyo D, Ancrenaz M, Morrogh-Bernard HC, Atmoko SSU, Wich SA, van Schaik CP (2009), Nest Building in Orangutan. In: Wich SA, Atmoko SSU, Setia TM, van Schaik CP (ed) Orangutans: Geographic Variation in Behavioral Ecology and Conservation. New York: Oxford University Press. pp. 269-278. https://doi.org/10.1093/acprof:oso/9780199213276.001.0001
- Pratiwi P and Garsetiasih R (2007), Sifat fisik dan Kimia Tanah Tanah serta Komposisi Vegetasi Di Taman Wisata Alam Tangkuban Parahu, Provinsi Jawa Barat. Jurnal Penelitian Hutan dan Konservasi Alam 4: 457-466. https://doi.org/10.20886/jphka.2007.4.5.457-466
- Proctor J (1999), Heath forests and acid soils. Botanical Journal of Scotland 51(1): 1–14. https://doi.org/10.1080/03746609908684920
- Purwaningsih and Kartawinata K (2018), Species Composition and Structure of Forests in the Muara Kendawangan Nature Reserve, West-Kalimantan, Indonesia. IOP Conf Ser: Earth Environ Sci 166:012005. https://doi.org/10.1088/1755-1315/166/1/012005
- Rahman DA (2010), Karakteristik Habitat dan Prefensi Pohon Sarang Orangutan (Pongo pygmaeus wurmbii) di Taman Nasional Tanjung Puting (Studi Kasus Camp Leakey). Jurnal Primatologi Indonesia 7(2): 37-50.
- Rayadin, Y, Qomari, N, Segah, H, Hanggito, MS, Priahutama AA, Pitoyo, D, Arifin, Z, Raharjo, Y S, Rohmadi, S, Irawan, D, Syurowo, GP, Simanjuntak, YR, Alfiyan, I, Iqbal M, Hadiyana, I, Azhari, A, Mujahidin, A, Zulfikar, MA, Mardiana, SR, Yudistira, MH, Michdad, FR, Apta, Y 2025 Model Pengelolaan Kawasan Hutan Bernilai Konservasi Tinggi (KBKT) Pada Habitat Orangutan Borneo Yayasan Pustaka Tropis Indonesia, Indonesia
- Rahmananantoandro, M 2020 Vegetation Structure and Wildlife Habitat Use in Tropical Forest Forest Ecology and Managemen Vol352 No1 pp 45-53. https://primata.ipb.ac.id/wp- content/uploads/2022/06/Vol-7-No-2-2010-Karakteristik-Habitat-dan-Preferensi-Pohon- Sarang-Orangutan-Pongo-Pygmaeus-Wurmbii-di-Taman-Nasional-Tanjung-Puting- Studi-Kasus-Camp-Leakey.pdf
- Riswan S and Kartawinata K (1991), Species strategy in early stage of secondary succession associated with soil properties status in a lowland mixed Dipterocarp forest and Kerangas forest in East Kalimantan. Tropics 1:13–34. https://doi.org/10.3759/tropics.1.13.
- Seaman DJI, Bernard H, Ancrenaz M, Coomes D, Swinfield T, Milodowski DT, Humle T, Struebig MJ (2019), Densities of Bornean Orang‐utans (Pongo pygmaeus morio) in Heavily Degraded Forest and Oil Palm Plantations in Sabah, Borneo. Am J Primatol, 81(8) https://doi.org/10.1002/ajp.23030.
- Singleton I, Wich SA, Nowak M, Usher G & Utami-Atmoko SS (2017), Pongo abelii. The IUCN Red List of Threatened Species 2017: E.T121097935A123797627. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T121097935A115575085.en.
- Russon AE, Kuncoro P, Ferisa A (2015), Orangutan behavior in Kutai National Park after drought and fire damage: Adjustments to short- and long-term natural forest regeneration: Orangutan Behavior in Recovering Forest. Am J Primatol 77:1276–1289. https://doi.org/10.1002/ajp.22480
- Sellan G, Thompson J, Majalap N (2019), Soil characteristics influence species composition and forest structure differentially among tree size classes in a Bornean heath forest. Plant Soil 438: 173–185. https://doi.org/10.1007/s11104-019-04000-5
- Soegianto A (1994), Ekologi Kuantitatif: Metode analisis populasi dan komunitas. Surabaya: Usaha Nasional.
- Sorensen T (1948), A method of establishing groups of equal amplitude in plant sociology based on similarity of species content, and its application to analyses of the vegetation on Danish commons. Biologiske skrifter 5: 1-34.
- Spehar SN, Rayadin Y (2017), Habitat use of Bornean Orangutans (Pongo pygmaeus morio) in an Industrial Forestry Plantation in East Kalimantan, Indonesia. Int J Primatol 38: 358– 384. https://doi.org/10.1007/s10764-017-9959-8
- Syuharni A, Hakeem K, Faridah, Hanum I, Ozturk M (2014), Ecology of the Coastal Heath Forest flora - A case study from Terengganu, Malaysia. Emir J Food Agric 26: 1114. https://doi.org/10.9755/ejfa.v26i12.19122
- Voigt M, Wich SA, Ancrenaz M, Meijaard E, Abram N, Banes GL, Campbell-Smith G, d’Arcy LJ, Delgado RA, Erman A, Gaveau D, Goossens B, Heinicke S, Houghton M, Husson SJ, Leiman A, Sanchez KL, Makinuddin N, Marshall AJ, Meididit A, Miettinen J, Mundry R, Musnanda Nardiyono, Nurcahyo A, Odom, K, Panda A, Prasetyo D, Priadjati A, Purnomo, Rafiastanto A, Russon AE, Santika T, Sihite J, Spehar S, Struebig M, Sulbaran- Romero E, Tjiu A, Wells J, Wilson KA, Kühl HS (2018), Global Demand for Natural Resources Eliminated More Than 100,000 Bornean Orangutans. Current Biology 28: 761- 769e5 https://doi.org/10.1016/j.cub.2018.01.053
- Wich SA, Gaveau D, Abram N, Ancrenaz M, Baccini A, Brend S, Curran L, Delgado RA, Erman A, Fredriksson GM, Goossens B, Husson SJ, Lackman I, Marshall AJ, Naomi A, Molidena E, Nardiyono, Nurcahyo A, Odom K, Panda A, Purnomo, Rafiastanto A, Ratnasari D, Santana AH, Sapari I, van Schaik CP, Sihite J, Spehar S, Santoso E, Suyoko A, Tiju A, Usher G, Atmoko SSU, Willems EP, Meijaard E (2012), Understanding the Impacts of Land-Use Policies on a Threatened Species: Is There a Future for the Bornean Orang-utan?. PLoS ONE 7:e49142 https://doi.org/10.1371/journal.pone.0049142
- Zoletto B and Cicuzza D (2022), Heath forest in tropical Southeast Asia, its ecology and conservation risk. In: DellaSala DA and Goldstein MI (ed) Imperiled: The Encyclopedia of Conservation. Amsterdam: Elsevier. https://doi.org/10.1016/B978-0-12-821139- 7.00235-X.
References
Ancrenaz M, Gumal M, Marshall AJ, Meijaard E, Wich SA & Husson S. Pongo pygmaeus. The IUCN Red List of Threatened Species 2016: E.T17975A123809220. https://doi.org/10.2305/IUCN.UK.2016-1.RLTS.T17975A17966347.en.
Ancrenaz M, Oram F, Nardiyono N, Silmi M, Jopony MEM, Voigt M, Seaman DJI, Sherman J, Lackman I, Traeholt C, Wich SA, Santika T, Struebig MJ, Meijaard E (2021), Importance of Small Forest Fragments in Agricultural Landscapes for Maintaining Orangutan Metapopulations. Front For Glob Change 4: 560944. https://doi.org/10.3389/ffgc.2021.560944
Areendran G, Sahana M, Raj K, Kumar R, Sivadas A, Kumar A, Deb S, Gupta VD (2020), A systematic review on high conservation value assessment (HCVs): Challenges and framework for future research on conservation strategy. Science of The Total Environment 709: 135425. https://doi.org/10.1016/j.scitotenv.2019.135425
Alikodra, HS (2020), Konservasi Satwa Liar dan Ekosistemnya. Bogor: IPB Press.
Anirudh NB, Van Veen FJF, Ripoll-Capilla B, Buckley BJW, Erb WM, Niun MA, Maimunah S, Makur KP, Armadiyanto, Estrada E, Boyd NS, Cheyne SM, Santiano Namaskari N, Husson SJ, Randi A, Seaman DJI, Deere NJ, Supriatna J, Struebig MJ, Harrison ME (2025), Lowland heath forests of Indonesian Borneo: ecological value and conservation challenges. Journal of Tropical Ecology 41: e19.
https://doi.org/10.1017/S0266467425100084
Ashton P (2014), On the forests of tropical Asia: lest the memory fade. Kew publishing. Budiana D (2021), Analisis Struktur Vegetasi Hutan Rawa Gambut dan Hubungannya dengan
Habitat Orangutan. Jurnal Ekologi Tropis 25(N3): 23-134.
Delgado Jr RA and Van Schaik CP (2000), The behavioral ecology and conservation of the
orangutan (Pongo pygmaeus): A tale of two islands. Evolutionary Anthropology: Issues,
News, and Reviews: Issues, News, and Reviews, 9(5): 201-218.
Din H, Metali F, Sukri RS (2015), Tree Diversity and Community Composition of the Tutong
White Sands, Brunei Darussalam: A Rare Tropical Heath Forest Ecosystem. International
Journal of Ecology 2015: 1–10. https://doi.org/10.1155/2015/807876
Galdikas BMF (1978), Adaptasi orangutan di Suaka Tanjung Putting Kalimantan Tengah.
Jakarta: UI Press.
Galdikas BMF (1982), Orang utans as seed dispersers at Tanjung Puting, Sentral Kalimantan:
implication for conservation. The Hague: Dr W Junk Publishers.
HCV Resource Network (1999), Available at: https://www.hcvnetwork.org [accessed 6
November 2025].
Hilwan I (2015), Karakteristik Biofisik Pada Berbagai Kondisi Hutan Kerangas di Kabupaten Belitung Timur, Provinsi Kepulauan Bangka Belitung. Jurnal Silvikultur Tropika 06(1): 59-65.
Husson SJ, Wich SA, Marshall AJ, Dennis RD, Ancrenaz M, Brassey R, Gumal M, Hearn AJ, Meijaard E, Simorangkir T, Singleton I (2009), Orangutan distribution, density, abundance and impacts of disturbance. In: Wich SA, Atmoko SSU, Setia TM, van Schaik CP (ed) Orangutans: Geographic Variation in Behavioral Ecology and Conservation. New York: Oxford University Press. pp. 77-96.
Ikbal IM, Din HHM, Tuah WH, Jaafar SM, Ahmad N, Sukri RS (2023), Review: Diversity, structure, and community composition of Bornean heath forest with a focus on Brunei Darussalam. Biodiversitas 24(5): 2814-2829. https://doi.org/10.13057/biodiv/d240535
Krebs CJ (1985), Ecology The Experimental Analysis of Distribution and Abundance. New York: Harper and Row Distribution.
Lohbeck M, Poorter L, Martínez‐Ramos M, Rodriguez‐Velázquez J, Van Breugel M, Bongers F (2014), Changing drivers of species dominance during tropical forest succession. Functional Ecology 28: 1052–1058. https://doi.org/10.1111/1365-2435.12240
Maimunah S, Capilla B, Armadiyanto, Harrison M (2019) Tree diversity and forest composition of a Bornean heath forest, Indonesia. IOP Conf Ser: Earth Environ Sci 270:012028 https://doi.org/10.1088/1755-1315/270/1/012028
Meijaard E, Albar G, Nardiyono, Rayadin Y, Ancrenaz M, Spehar S (2010), Unexpected Ecological Resilience in Bornean Orangutans and Implications for Pulp and Paper Plantation Management. PLoS ONE 5:e12813. https://doi.org/10.1371/journal.pone.0012813
Mitchell RJ, Auld MHD, Le Duc MG, Robert MH (2000), Ecosystem stability and resilience: a review of their relevance for the conservation management of lowland heaths. Perspectives in Plant Ecology, Evolution and Systematics 3: 142–160. https://doi.org/10.1078/1433-8319-00009
Mukhlisi and Gunawan W (2019), Karakteristik Vegetasi Habitat Orangutan (Pongo pygmaeus morio) di PT Kaltim Prima Coal Kalimantan Timur. Jurnal Biologi Al-Kauniyah 12(1): 63-72.
Mueller-Dumbois D, Ellenberg H (1974), Aims and Methods of Vegetation of Ecology. New York: Willey and Sons Inc.
Nowak MG, Rianti P, Wich SA, Meijaard E & Fredriksson G (2017), Pongo tapanuliensis. The IUCN Red List of Threatened Species 2017: E.T120588639A120588662. https://doi.org/10.2305/IUCN.UK.2017-3.RLTS.T120588639A120588662.en.
Prasetyo D, Ancrenaz M, Morrogh-Bernard HC, Atmoko SSU, Wich SA, van Schaik CP (2009), Nest Building in Orangutan. In: Wich SA, Atmoko SSU, Setia TM, van Schaik CP (ed) Orangutans: Geographic Variation in Behavioral Ecology and Conservation. New York: Oxford University Press. pp. 269-278. https://doi.org/10.1093/acprof:oso/9780199213276.001.0001
Pratiwi P and Garsetiasih R (2007), Sifat fisik dan Kimia Tanah Tanah serta Komposisi Vegetasi Di Taman Wisata Alam Tangkuban Parahu, Provinsi Jawa Barat. Jurnal Penelitian Hutan dan Konservasi Alam 4: 457-466. https://doi.org/10.20886/jphka.2007.4.5.457-466
Proctor J (1999), Heath forests and acid soils. Botanical Journal of Scotland 51(1): 1–14. https://doi.org/10.1080/03746609908684920
Purwaningsih and Kartawinata K (2018), Species Composition and Structure of Forests in the Muara Kendawangan Nature Reserve, West-Kalimantan, Indonesia. IOP Conf Ser: Earth Environ Sci 166:012005. https://doi.org/10.1088/1755-1315/166/1/012005
Rahman DA (2010), Karakteristik Habitat dan Prefensi Pohon Sarang Orangutan (Pongo pygmaeus wurmbii) di Taman Nasional Tanjung Puting (Studi Kasus Camp Leakey). Jurnal Primatologi Indonesia 7(2): 37-50.
Rayadin, Y, Qomari, N, Segah, H, Hanggito, MS, Priahutama AA, Pitoyo, D, Arifin, Z, Raharjo, Y S, Rohmadi, S, Irawan, D, Syurowo, GP, Simanjuntak, YR, Alfiyan, I, Iqbal M, Hadiyana, I, Azhari, A, Mujahidin, A, Zulfikar, MA, Mardiana, SR, Yudistira, MH, Michdad, FR, Apta, Y 2025 Model Pengelolaan Kawasan Hutan Bernilai Konservasi Tinggi (KBKT) Pada Habitat Orangutan Borneo Yayasan Pustaka Tropis Indonesia, Indonesia
Rahmananantoandro, M 2020 Vegetation Structure and Wildlife Habitat Use in Tropical Forest Forest Ecology and Managemen Vol352 No1 pp 45-53. https://primata.ipb.ac.id/wp- content/uploads/2022/06/Vol-7-No-2-2010-Karakteristik-Habitat-dan-Preferensi-Pohon- Sarang-Orangutan-Pongo-Pygmaeus-Wurmbii-di-Taman-Nasional-Tanjung-Puting- Studi-Kasus-Camp-Leakey.pdf
Riswan S and Kartawinata K (1991), Species strategy in early stage of secondary succession associated with soil properties status in a lowland mixed Dipterocarp forest and Kerangas forest in East Kalimantan. Tropics 1:13–34. https://doi.org/10.3759/tropics.1.13.
Seaman DJI, Bernard H, Ancrenaz M, Coomes D, Swinfield T, Milodowski DT, Humle T, Struebig MJ (2019), Densities of Bornean Orang‐utans (Pongo pygmaeus morio) in Heavily Degraded Forest and Oil Palm Plantations in Sabah, Borneo. Am J Primatol, 81(8) https://doi.org/10.1002/ajp.23030.
Singleton I, Wich SA, Nowak M, Usher G & Utami-Atmoko SS (2017), Pongo abelii. The IUCN Red List of Threatened Species 2017: E.T121097935A123797627. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T121097935A115575085.en.
Russon AE, Kuncoro P, Ferisa A (2015), Orangutan behavior in Kutai National Park after drought and fire damage: Adjustments to short- and long-term natural forest regeneration: Orangutan Behavior in Recovering Forest. Am J Primatol 77:1276–1289. https://doi.org/10.1002/ajp.22480
Sellan G, Thompson J, Majalap N (2019), Soil characteristics influence species composition and forest structure differentially among tree size classes in a Bornean heath forest. Plant Soil 438: 173–185. https://doi.org/10.1007/s11104-019-04000-5
Soegianto A (1994), Ekologi Kuantitatif: Metode analisis populasi dan komunitas. Surabaya: Usaha Nasional.
Sorensen T (1948), A method of establishing groups of equal amplitude in plant sociology based on similarity of species content, and its application to analyses of the vegetation on Danish commons. Biologiske skrifter 5: 1-34.
Spehar SN, Rayadin Y (2017), Habitat use of Bornean Orangutans (Pongo pygmaeus morio) in an Industrial Forestry Plantation in East Kalimantan, Indonesia. Int J Primatol 38: 358– 384. https://doi.org/10.1007/s10764-017-9959-8
Syuharni A, Hakeem K, Faridah, Hanum I, Ozturk M (2014), Ecology of the Coastal Heath Forest flora - A case study from Terengganu, Malaysia. Emir J Food Agric 26: 1114. https://doi.org/10.9755/ejfa.v26i12.19122
Voigt M, Wich SA, Ancrenaz M, Meijaard E, Abram N, Banes GL, Campbell-Smith G, d’Arcy LJ, Delgado RA, Erman A, Gaveau D, Goossens B, Heinicke S, Houghton M, Husson SJ, Leiman A, Sanchez KL, Makinuddin N, Marshall AJ, Meididit A, Miettinen J, Mundry R, Musnanda Nardiyono, Nurcahyo A, Odom, K, Panda A, Prasetyo D, Priadjati A, Purnomo, Rafiastanto A, Russon AE, Santika T, Sihite J, Spehar S, Struebig M, Sulbaran- Romero E, Tjiu A, Wells J, Wilson KA, Kühl HS (2018), Global Demand for Natural Resources Eliminated More Than 100,000 Bornean Orangutans. Current Biology 28: 761- 769e5 https://doi.org/10.1016/j.cub.2018.01.053
Wich SA, Gaveau D, Abram N, Ancrenaz M, Baccini A, Brend S, Curran L, Delgado RA, Erman A, Fredriksson GM, Goossens B, Husson SJ, Lackman I, Marshall AJ, Naomi A, Molidena E, Nardiyono, Nurcahyo A, Odom K, Panda A, Purnomo, Rafiastanto A, Ratnasari D, Santana AH, Sapari I, van Schaik CP, Sihite J, Spehar S, Santoso E, Suyoko A, Tiju A, Usher G, Atmoko SSU, Willems EP, Meijaard E (2012), Understanding the Impacts of Land-Use Policies on a Threatened Species: Is There a Future for the Bornean Orang-utan?. PLoS ONE 7:e49142 https://doi.org/10.1371/journal.pone.0049142
Zoletto B and Cicuzza D (2022), Heath forest in tropical Southeast Asia, its ecology and conservation risk. In: DellaSala DA and Goldstein MI (ed) Imperiled: The Encyclopedia of Conservation. Amsterdam: Elsevier. https://doi.org/10.1016/B978-0-12-821139- 7.00235-X.