Tree biodiversity in Bornean lowland forest: What are the key species for forest city development in the new capital city of Indonesia?

PLOS ONE | https://doi.org/10.1371/journal.pone.0320489 April 8, 2025 9 / 19 PLOS ONE Tropical urban tree selection position among the IVIs for genera. These results showed that the study location is comprised of a mix of secondary forests (from various histories) as well as areas that are less disturbed and are typical lowland evergreen rain forest, a.k.a. mixed dipterocarp forest (MDF). Species categories Most tree species were fast-growing and are a source of animal food (S1 Table). One hundred and twenty-three tree species were known to have potential social and economic functions for the people of Borneo, both as a source of food and medicine. Based on the IUCN Red List categorisa- tion, 11.7% of the species were threatened, one of which (Mangifera casturi; Anacardiaceae) was declared Extinct in the Wild. This species was only found as a cultivated fruit tree at Sotek Gar- den. All Critically Endangered species (8) belonged to the Dipterocarpaceae, namely Anthoshorea lamellata, Dipterocarpus cornutus, D. kunstleri, Hopea mengarawan, H. rudiformis, Rubroshorea johorensis, Shorea inappendiculata, and Vatica venulosa. The Dipterocarpaceae also dominated as the climax species by contributing 40 species out of a total of 97 climax species found at the study site. A total of seven Endangered species were found: Agathis borneensis (Araucariaceae), Anisoptera costata (Dipterocarpaceae), Dipterocarpus grandiflorus (Dipterocarpaceae), Santiria rubiginosa (Burseraceae), Rubroshorea pauciflora (Dipterocarpaceae), Shorea dasyphylla (Dip-

terocarpaceae), and Syzygium scortechinii, while there were 33 species in the Vulnerable category. Only one species was found which is legally protected under Indonesian regulations, namely bandang (Borassodendron borneense; Arecaceae), as one of the endemic palms of Borneo. Species selection for rehabilitation Species selection for rehabilitation was based on criteria including conservation status, ende- mism, climax species, distribution, potential as a food source, ethnobotanical uses, key animal food sources, and fast-growing species. Among 420 species (S1 Table), we found one species as the first priority for rehabilitation followed by 15 species, 89 species, and 315 species for the second, third, and fourth priorities, respectively (Table 5). Discussion Status of tree species diversity Biodiversity is crucial to support human well-being and to provide life-supporting services such as clean water, food, pollination, climate control, and flood prevention. It also plays roles in Table 4. The top ten species, genera and families based on IVI in the forest locations in the vicinity of Ibu Kota Negara, East Kalimantan, Indonesia. Species IVI Genus IVI Family IVI Syzygium sp. 6.52 Rubroshorea 28.32 Dipterocarpaceae 34.57 Macaranga gigantea 5.29 Macaranga 15.98 Euphorbiaceae 21.81 Rubroshorea parvifolia 5.12 Syzygium 11.99 Lauraceae 15.55 Eusideroxylon zwageri 4.60 Artocarpus 7.76 Myrtaceae 14.05 Strobocalyx arborea 4.49 Litsea 5.21 Moraceae 11.94 Rubroshorea ovalis 4.08 Lithocarpus 4.91 Phyllanthaceae 9.67

Rubroshorea smithiana 3.57 Eusideroxylon 4.85 Annonaceae 9.12 Vitex pinnata 3.20 Madhuca 4.80 Myristicaceae 9.04 Madhuca kingiana 3.07 Pternandra 4.71 Malvaceae 9.01 Schima wallichii 3.04 Strobocalyx 4.71 Sapotaceae 8.90 https://doi.org/10.1371/journal.pone.0320489.t004