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Summary

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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

Species	Hylobates moloch
Area	175 km²
Coordinates	Lat: -7.21584 , Lon: 109.90651
Type of site	Non-protected area
Habitat types	Subtropical/tropical moist montane forest, Subtropical/tropical heavily degraded former forest
Type of governance

Types of sites Governance types Habitat types

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 reported for Dieng Plateau

Species	Year	Total number groups (95% CI)	Density [groups/km²] (95% CI)	Total number indiv. (95% CI)	Area	Method	Source	Comments	A.P.E.S. database ID
Hylobates moloch	2018				Dieng Plateau (175 km²)	Line transects	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

Sampling methods Analytical frameworks

Threats

Table 3. Threats to apes reported for Dieng Plateau

Category	Specific threats	Threat level	Description	Year of threat
2 Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	Present (unknown severity)	Several relatively flat areas converted into cropland, such as dry crop and rice field (Widyastuti et al. 2020).	Ongoing (2020)
2 Agriculture & aquaculture	2.2 Wood & pulp plantations	Present (unknown severity)	Plantation forest next to natural forest, such as pine tree, rubber tree, and dammar tree (Widyastuti et al. 2020).	Ongoing (2020)
4 Transportation & service corridors	4.1 Roads & railroads	Present (unknown severity)	Roads built to support development of tourist parks (Widyastuti et al. 2020).	Ongoing (2020)
5 Biological resource use	5.2 Gathering terrestrial plants	Present (unknown severity)	Collection of NTFP such as honey (Widyastuti et al. 2020).	Ongoing (2020)
5 Biological resource use	5.3 Logging & wood harvesting	High (more than 70% of population affected)	Most of the natural forest patches are secondary forest due to logging in the past (Widyastuti et al. 2020).	Ongoing (2020)

Threats

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).

Challenges

Table 5. Challenges reported for Dieng Plateau

Challenges	Specific challenges	Source	Year(s)
	Not reported

Challenges

Enablers

Table 6. Enablers reported for Dieng Plateau

Enablers	Specific enablers	Source	Year(s)
1 Site management
2 Resources and capacity
3 Engaged community
4 Institutional support
5 Ecological context
6 Safety and stability

Enablers

Research activities

Documented behaviours

Table 7. Behaviours documented for Dieng Plateau

Category	Behavior	Observation type	Prevalence	Observation dates	Source	Habituation	Species	Comment
	Not reported

Behaviours

Exposure to climate change impacts

External links

References

Widyastuti, S., Perwitasari-Farajallah, D., Prasetyo, L. B., Iskandar, E., & Setiawan, A. (2020). Maxent modelling of habitat suitability for the endangered javan gibbon (Hylobates moloch) in less-protected Dieng Mountains, Central Java. IOP Conference Series: Earth and Environmental Science, 457(1), 012014. doi:10.1088/1755-1315/457/1/012014

Page created by: APES Atlas Team Date: 2022-01-28