Deforestation in Borneo threatens three endangered, endemic plant species

Deforestation in Borneo threatens three endangered, endemic plant species

  • The rampant deforestation for monoculture plantation and logging in western Indonesian Borneo has exacerbated the extinction risks of three plant species endemic to the island’s riparian lowland rainforests, a new study said.
  • The researchers are calling for stricter protection of the forest fragments as a key conservation strategy for the three plant species and for further research to be done to better understand the species’ population status so as to improve their management.
  • The island of Borneo, which is split between Indonesia, Malaysia and Brunei, has for the last few decades lost more than a third of its forests due to fires, logging, mining and industrial plantations, particularly oil palms.

JAKARTA — The rampant deforestation for monoculture plantation and logging in western Indonesian Borneo has exacerbated the extinction risks of three plant species endemic to the island’s riparian lowland rainforests, a new study said.

A group of Indonesian researchers has reported that three Bornean plant species, Vatica rynchocarpa, V. havilandii and V. cauliflora, found in the lowland forest fragments along the upper Kapuas River in West Kalimantan province, were threatened by small-holder farming, industrial agriculture and timber extraction.

These patches of riparian forests were unprotected, as they have been designated as “other-use” or APL, rendering them available for any development and most likely to see further deforestation, added the authors in their report published in the April issue of Journal for Nature Conservation.

“I don’t think that this is first research on plant species in Borneo, but ours is the first population study on the three species which are threatened with extinction and one of them is very endemic, in their natural habitat,” Enggal Primananda, a forest researcher at Indonesia’s National Research and Innovation Agency (BRIN) who is the lead author of the paper, told Mongabay in an interview.

Indonesia’s West Kalimantan province on the island of Borneo. Muara Sungai Landak is operating near the coast, not far from the provincial capital Pontianak. Image by TUBS via Wikimedia Commons (CC BY-SA 3.0).
Deforestation in Borneo threatens three endangered, endemic plant species
Former lowland rainforest replaced with a monoculture plantation in West Kalimantan, Indonesia. Image courtesy of Rhett Butler/Mongabay.

Enggal said the population assessment of the three Vatica species from the International Union for Conservation of Nature (IUCN) prompted his team to carry out their field study. The IUCN Red List of Threatened Species shows that the V. rynchocarpa is endangered, as the plant species has faced up to 70% decline in the past decade, while the V. havilandii and V. cauliflora are critically endangered, meaning that they are close to extinction in the wild.

Enggal noted that V. cauliflora could only be found in West Kalimantan’s Kapuas Hulu district, while the other two could still be found in the Bornean forests of Malaysia and Brunei. Incidentally, he said, V. cauliflora typically also grew in dryland areas that were favorable among people for converting into plantations, such as rubber (Hevea brasiliensis) and the medicinal plant kratom (Mitragyna speciosa). Recent population surveys located a total of 179 individuals of the species, the paper said.

“We wanted to find out whether these species still exist in the wild, what are the threats that cause the highest potential for extinction, and the population status in their habitat,” Enggal said.

Ex-situ collection of (A) Vatica rynchocarpa, (B) V. havilandii, and (C) V. cauliflora. Image courtesy of Enggal Primananda et al.

The Kapuas River represents one of the oldest tropical peat formations. It empties into the Kapuas Hulu plateau, flows through the steep slope in the western part of the plateau, then descends into plains. This region has a very wet climate with an even distribution of rainfall throughout the year.

The authors conducted field surveys July 4-18, 2022, and assessed the population structure of each species. Through proximity analysis, they calculated the distance of each individual from the river to assess its effect on the species distribution. A total of 13 locations were surveyed during the study with a total covered distance of 26 kilometers (16 miles). In addition to the population of V. cauliflora, they located 317 individuals of V. rynchocarpa and 568 individuals of V. havilandii.

The island of Borneo is split between Indonesia, Malaysia and Brunei. A group of scientists published in 2022 a study of a deforestation trend model that projected 74,419 square kilometers (28,733 square miles) of forest — an area a tenth the size of Italy — would be lost between 2018 and 2032. The estimate was based on forest loss of 59,949 km2 (23,146 mi2) between 2000 and 2017 across Borneo.

In 1973, three-quarters of Borneo, the world’s third-largest island, was still forested and home to many tropical wildlife species. But four decades of fires, logging, mining and industrial plantations, particularly oil palms, destroyed more than a third of Borneo’s rainforests.

Enggal said he presented his field findings to the managing agencies of the Kapuas Hulu forests immediately after his team completed their surveys. The researchers are calling for stricter protection of the forest fragments as a key conservation strategy for the three plant species and for further research to be done to better understand the species’ population status so as to improve their management.

“There isn’t much attention yet from the forestry sector given towards plant conservation in comparison to animal conservation, so the research and information is still very limited especially for plants that are threatened with extinction,” Enggal said.

The main threats to populations of V. rynchocarpa, V. havilandii and V. cauliflora in Kapuas Hulu, West Kalimantan are (A) conversion into rubber (H. brasiliensis), (B) medicinal plant kratom (M. speciosa) plantations, (C) land preparation for agricultural areas and (D) timber extraction for house construction and firewood. Image courtesy of Enggal Primananda et al.

Citations:

Primananda, E., Sunardi, Fefirenta, A. D., Rahmawati, K., Mira, F. R., Budi, S. W., & Robiansyah, I. (2023). Survey for threatened plants in riparian fragmented forests: A case study on three Vatica (Dipterocarpaceae) species in Kapuas Hulu, West Kalimantan. Journal for Nature Conservation, 72. doi: 10.1016/j.jnc.2023.126367

Voigt, M., Kühl, H. S., Ancrenaz, M., Gaveau, D., Meijaard, E., Santika, T., … Rosa, I. M. (2022). Deforestation projections imply range-wide population decline for critically endangered Bornean orangutan. Perspectives in Ecology and Conservation. doi:10.1016/j.pecon.2022.06.001

Voigt, M., Wich, S. A., Ancrenaz, M., Meijaard, E., Abram, N., Banes, G. L., … Kühl, H. S. (2018). Global demand for natural resources eliminated more than 100,000 Bornean orangutans. Current Biology28(5), 761-769.e5. doi:10.1016/j.cub.2018.01.053

Basten Gokkon is a senior staff writer for Indonesia at Mongabay. Find him on Twitter @bgokkon.

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