Biological richness of Gunung Slamet, Central Java, and the need for its protection

Designating protected areas remains a core strategy in biodiversity conservation. Despite high endemism, montane forests across the island of Java are under-represented in Indonesia's protected area network. Here, we document the montane biodiversity of Gunung Slamet, an isolated volcano in Central Java, and provide evidence to support its increased protection. During September-December 2018, we surveyed multiple sites for birds, primates, terrestrial mammals, reptiles, amphibians and vegetation. Survey methods included transects, camera traps and targeted searches at six sites, at altitudes of 970-2,512 m. We used species distribution models for birds and mammals of conservation concern to identify priority areas for protection. We recorded 99 bird species (13 globally threatened), 15 mammals (five globally threatened) and 17 reptiles and amphibians (two endemic). Our species distribution models showed considerable cross-taxon congruence between important areas on Slamet's upper slopes, generally above 1,800 m. Particularly important were records of the endemic subspecies of the Endangered Javan laughingthrush Garrulax rufifrons slamatensis, not recorded in the wild since 1925, the Endangered Javan gibbon Hylobates moloch and Javan surili Presbytis comata, and the Vulnerable Javan lutung Trachypithecus auratus and Javan leopard Panthera pardus melas. Recent forest loss has been modest, at least 280 km(2) of continuous forest remain above 800 m, and our surveys show that forest habitats are in good condition. However, the mountain is widely used by trappers and hunters. Given its importance for biodiversity conservation, we discuss different options for improving the protection status of Gunung Slamet, including designation as a National Park or Essential Ecosystem.

Automated summary

Designating protected areas is crucial for biodiversity conservation, and the montane biodiversity of Gunung Slamet in Central Java, Indonesia, is documented in this study. Important areas for protection have been identified on the upper slopes of the mountain, although the region is facing threats from trappers and hunters. Forest habitats in the area are in good condition, but recent forest loss is a concern.