Dieng Plateau

Asia > Indonesia > Dieng Plateau

Summary

• Javan gibbons (Hylobates moloch) are present in the Dieng Plateau.
• The population size is unknown.
• The population trend is unknown.
• The survey site has a total size of 175 km².
• Key threats to gibbons are forest fragmentation due to logging and agriculture, and collection of NTFPs.
• Conservation activities are not documented.

Site characteristics

The site consists of a part of a fragmented natural forest in the Dieng Plateau, Central Java province, Indonesia. Dieng is known as a volcanic complex with numerous craters (Widyastuti et al. 2020). The site, which was part of a survey, is located in the northern part of the mountains. The area has hilly terrain, complex riverine, valley, and ridges (Widyastuti et al. 2020). The natural forest in the area is home to a variety of flora and fauna, especially for all primates of Java. Those are Macaca fascicularis, Trachypitechus auratus, Presbytis fredericae, Nicticebus javanicus and Hylobates moloch (Widyastuti et al. 2020).

Table 1. Basic site information for Dieng Plateau

Area	175 km²
Coordinates	-7.21584 109.90651
Designation	Unclassified
Habitat types	Subtropical/tropical moist montane forest, Subtropical/Tropical Heavily Degraded Former Forest

IUCN habitat categories Site designations

Ape status

A 2018 survey aimed to identify the habitat suitability model (HSM) for Javan gibbons in the Dieng highland and the most influencing biophysical variables (Widyastuti et al. 2020). A total of 305 occurrence data recorded in extensive field surveys and 11 variables were maintained for HSM in presence-only machine learning, maximum entropy (MaxEnt). Suitable gibbon habitats were predicted as 81.286 km2 in the surveyed area (Widyastuti et al. 2020). Relatively large areas of suitable habitat are located in Sokokembang, Linggoasri-Mendolo, and western of Kembanglangit. The most important variables were natural forest, elevation, distance to cropland and land surface temperature (Widyastuti et al. 2020).

Table 2. Ape population estimates in Dieng Plateau

Species	Year	Total number indiv. (95% CI)	Total number groups (95% CI)	Density ​​[groups/km²​] (95% CI)	Area	Method	Source	Comments	A.P.E.S. database ID
Hylobates moloch	2018				175 km2	Line transects (Distance)	Widyastuti et al. 2020	In addition to line transects, faecal samples, vocalisations, and sightings information from trusted villagers were considered as indirect evidence to obtain a robust occurrence data

Threats

Table 3. Threats to apes in Dieng Plateau

Category	Specific threats	Threat level	Quantified severity	Description	Year of threat
1. Residential & commercial development		Unknown
2. Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	Present, but threat severity unknown		Several relatively flat areas converted into cropland, such as dry crop and rice field (Widyastuti et al. 2020).	Ongoing (2020)
	2.2 Wood & pulp plantations	Present, but threat severity unknown		Plantation forest next to natural forest, such as pine tree, rubber tree, and dammar tree (Widyastuti et al. 2020).	Ongoing (2020)
3. Energy production & mining		Unknown
4. Transportation & service corridors	4.1 Roads & railroads	Present, but threat severity unknown		Roads built to support development of tourist parks (Widyastuti et al. 2020).	Ongoing (2020)
5. Biological resource use	5.2 Gathering terrestrial plants	Present, but threat severity unknown		Collection of NTFP such as honey (Widyastuti et al. 2020).	Ongoing (2020)
	5.3 Logging & wood harvesting	High		Most of the natural forest patches are secondary forest due to logging in the past (Widyastuti et al. 2020).	Ongoing (2020)
6. Human intrusion & disturbance		Unknown
7. Natural system modifications		Unknown
8. Invasive & other problematic species, genes, diseases		Unknown
9. Pollution		Unknown
10. Geological Events		Absent
11. Climate change & severe weather		Unknown
12. Other options		Absent

IUCN Threats list

Conservation activities

The forested areas at the site are managed by Perum Perhutani (Indonesia state-owned forestry enterprise) which are mainly responsible for forest production (Widyastuti et al. 2020).

Table 4. Conservation activities in Dieng Plateau

Category	Specific activity	Description	Year of activity
1. Residential & commercial development	Not reported
2. Agriculture & aquaculture	Not reported
3. Energy production & mining	Not reported
4. Transportation & service corridors	Not reported
5. Biological resource use	Not reported
6. Human intrusion & disturbance	Not reported
7. Natural system modifications	Not reported
8. Invasive & other problematic species, genes, diseases	Not reported
9. Pollution	Not reported
10. Education & Awareness	Not reported
11. Habitat Protection	Not reported
12. Species Management	Not reported
13. Livelihood; Economic & Other Incentives	Not reported

Conservation activities list (Junker et al. 2017)

Challenges

Table 5. Challenges reported for Dieng Plateau

Challenge	Source
Not reported

Research activities

Documented behaviours

Table 6. Ape behaviors reported for Dieng Plateau

Behavior	Source
Not reported

External links

Relevant datasets

A.P.E.S Portal

References

Widyastuti, S., Perwitasari-Farajallah, D., Prasetyo, L. B., Iskandar, E., & Setiawan, A. (2020, February). Maxent modelling of habitat suitability for the endangered javan gibbon (Hylobates moloch) in less-protected Dieng Mountains, Central Java. In IOP Conference Series: Earth and Environmental Science (Vol. 457, No. 1, p. 012014). IOP Publishing.

Page completed by: A.P.E.S. Wiki team Date: 28/01/2022