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<Technology Needs for Lake Management in Indonesia - Investigation of Rawa Danau and Rawa Pening, Java> E. Assessment of Present Conservation Value of Rawa Danau 1. Special attributes which merit attention The present area of degrading swamp forest in Rawa Danau is now the last substantial area of peat swamp forest which remains in Java. Other fragments of swamp forest may still exist in Java, but none of these are believed to be more than three or four hectares in area (Whitten, Soeriaatmadja and Affif, 1996). Such swamp forests probably covered much of the Javanese lowlands in the past, but large areas, such as Segara Anakan, have been drained and cleared for rice production and development. Much interest then centres on the conservation value of this area as this will affect decisions on the management objectives for the caldera as a whole. Much of the swamp forest, but not all, lies within an area of 2,500ha, designated since 1921 as a Nature Reserve, and now legally Cagar Alam. The lake which once existed in Rawa Danau has entirely vanished during the last 60 years, after being drained. 2. Land use within the caldera at present There are no data on the area of various land and vegetation types within the caldera at present. The area of swamp forest and of open water (lake) appears to have decreased steadily over the years. The total catchment area is listed in the Case Studies Document as 22,620ha. In the Case Studies Document, the areas within the catchment under different vegetation and land use types are listed in table 2.6.1 in that Document, the information coming from RLKT, 1986. Those data are reprinted here.
In the Encyclopaedie (1917) the area of the swamp is given as 50 sq km (5,000ha). The present area of swamp forest within the caldera is much smaller. The PHPA/AWB 1993 Report, using 1986 aerial photographs, reports 630ha of open herbaceous swamp, and 1,230ha of swamp forest. This is a total swamp area of 1,860ha. The 1993 Report also includes a number of useful maps which show the approximate areas of the different vegetation types and their distribution within the area of the caldera and Gunung Tukung Gede. The swamp forest appears to be in scattered patches throughout the area of the caldera at present, suggesting continuous loss of trees and forest area during recent years. It is noted in the 1993 Report that there is now no continuous canopy in the swamp forest which has become an open forest, presumably due to illegal felling of trees. It appears that the swamp forest is not surviving under the present conditions in the caldera. In the (1993) Report by PHPA/AWB this is attributed to the impact of human activity of various kinds on the swamp vegetation. The area of the Cagar Alam Nature Reserve is given as 2,500ha, within which the swamp forest is supposed to be protected from human interference. It is probable that the area of swamp forest has been adversely affected by the lowering of the water level and the resultant drying out of the superficial soils in the caldera. This drying process would have led to changes in the chemical composition of the soils (as mentioned previously) which might also disadvantage some of the vegetation in the caldera. The lake is reported (Encyclopaedie, 1917) to have occupied a few square kilometres, and to have been up to 10 metres in depth in 1910. In the Case Studies Document the lake area is recorded as being less than 11ha, as based on the 1981 aerial photographs. During the present investigations, the area of open water was much less than 11ha, and probably about 2ha at most. Examination of the scattered spot heights recorded in the caldera suggest that Endert's (1993) lake lay from about the junction of the Ci Danau river and the Ci Kalumpang river to the large isolated hill (Gn. Jamungkal) north of the Ci Danau river about 2km to the east of the river junction. 3. Ecological informatino on vegetation and wildlife This assessment is based mainly on the report of the PHPA/AWB investigation of 1993. In this report previous survey data are assessed and evaluated. The report is an invaluable source of information on the status of many of the species reported to live in the area. In this section, the frequent references to this report are made as "the 1993 report". Additional information comes from the recent publication by Whitten, Soeriaatmadja and Afiff (1996), on the Ecology of Java and Bali. While the present report concerns primarily Rawa Danau, it is impossible to disregard the importance of the adjacent 1,700ha of conservation area called Gunung Tukung Gede. This is the area of mountains on the north and east of Rawa Danau which have formed an effective barrier limiting access to the Rawa from these directions. The entire area of the Rawa is surrounded by hills, the actual Rawa being the floor of an ancient caldera, the surrounding hills forming the walls of the caldera. The hills to the west and south are lower and have allowed access for extensive settlements. 4. Vegetation of Rawa Danau The vegetation of the swamp forest is unique in Java, and contains species which now survive nowhere else in Java. The 1993 report lists 131 species which have been recorded from the area. This list comprises identifications made by different survey groups over a number of years. The list merits revision and confirmation after thorough taxonomic study. Attention is drawn to fifteen plant species in the 1993 report. Tree species present in Rawa Danau include - Elaeocarpus littoralis (Elae.) Mangifera gedebe (Anac.) Alstonia spathulata (Apoc.) These three species are found commonly in swamps in Sumatra and Kalimantan, though these too are being drained rapidly for agriculture and settlement. These species may well be extinct now in other areas in Java where they probably occurred previously. One species of climber is recognised to be an endemic, confined entirely to the area of the caldera. This is Derris danauensis. Other species listed in the 1993 report are very rare outside the caldera and probably are approaching extinction in the rest of Java. Other plants have been claimed as endemic species restricted to the area of the caldera. The exact taxonomic status of some of these has been questioned. These include species such as Glochidion palustre, Coix palustre and Alocasia bantamensis. Descriptions of these populations suggest that they represent variants sufficiently distinct from allied populations occurring in Sumatra and Kalimantan to merit detailed assessment of their similarity prior to relegation as varieties of other species. Rawa Danau is the only known locality in Java in which the impressive giant sedge Thoracostachyum sumatrana occurs. van Steenis (1936) reported the occurrence in the Rawa of Machaerina rubiginosa, Cyrtosperma merkusii, Hydrocharis dubia, Nepenthes mirabilis and Trapa maximoviscii, all of which are recognised to be exceedingly rare on Java. Conclusion - Vegetation analysis suggests that the area of Rawa Danau merits conservation, as it is the last remnant of an ecosystem which was once common throughout Java. It contains at least one species endemic to the area and entirely restricted to it, as well as numbers of species, including some trees, which are no longer found elsewhere on Java, as far as is known. The vegetation of the area would merit detailed study, to resolve the taxonomic status of some plant populations. 5 Fauna of Rawa Danau It is recognised that some animals such as mammals and birds can move freely from one area to another. So species recorded in observations and from traps in Rawa Danau may actually be more commonly found in the forest of Gunung Tukung Gede, and vice versa. The proximity of the forest types to each other in some places allows a high degree of mobility between the areas concerned. For instance, at Gunung Jamungkal, the large hill on the north bank of the Ci Danau two km north east of the junction of the Ci Danau and the Ci Kalumpang, the "Hutan Lindung" (preserved forest) of the hill, which appears to be very well preserved, is in direct contact with the swamp forest along the banks of the Ci Danau. The forest of Gunung Tukung Gede supports a number of species at present or in the recent past (such as Leopoldamys sabanus and Maxomys surifer) which suggest strongly that the forest is relatively undisturbed lowland rainforest, a very unusual situation in West Java, outside Ujung Kulon National Park. These are rodents which typically avoid areas where there is human contact or disturbance of the environment by human activity. Four species of primates are found in the area, the grizzled leaf monkey (Presbytis comata) and the slow loris (Nycticebus coucang) being under most threat. The slow loris appears to be confined to the hill forests of gunung Tukung Gede. The common ebony leaf monkey (Trachypithecus aurata) occurred in all types of forest in the area including the swamp forest. It is reported as being an inhabitant of the lower levels of the forest while Presbytis comata was more commonly seen in the upper levels of the forest canopy. The long-tailed macaque (Macaca fascicularis) is common in the swamp forest. Presbytis comata is protected under Indonesian law, endemic to Java and assessed as endangered by IUCN. It is supposed to occur in hill forests bordering the swamp forest areas. The population density of this species is very low in the caldera compared to reports from other areas. The Javan silvery gibbon (Hylobates moloch) may well now be extinct in this area, having last been reported in 1982. Its penetrating calls would be expected to bring it to the attention of staff of PHPA at intervals, even if particular individuals were not seen. This species is endemic to Java, is protected by Indonesian law, and is assessed as endangered by IUCN. The absence of this species after its presence was recorded regularly prior to 1980 is particularly regrettable and indicates the extent of decline in conservation value of the area in recent years. West Java is ranked highly in the IUCN "Action Plan for Asian Primates" (Eudey, 1987), and Presbytis comata is noted in particular, as a species with a very high conservation priority. The occurrence of otters in the area is of some interest as these are obviously restricted in distribution to the area of the swamp. Two species are reported to occur in the swamp. Aonyx cinerea, the oriental small clawed otter, and Lutrogale perspicillata, the smooth coated otter. Otters are not protected under Indonesian law and there is not enough information on their abundance and distribution in Indonesia to allow allocation to a category under IUCN assessment. The occurrence of Lutrogale is important as this species is believed to be rare in Java. Among terrestrial carnivores, the occurrence of the fishing cat (Felis viverrima) is noteworthy. The present abundance and distribution in Java of this remarkable animal is unknown. The majority of sightings in Java date from the period of the 1930s. It was then recorded primarily from coastal mangrove swamps. According to the 1993 report it is probably to be considered as endangered in Java because of the loss of mangrove swamps. The report of this species from Rawa Danau is the only one from a fresh water area in Java. It is known to occur in the swamps of the Padang-Sugihan estuary in Sumatra but there it is considered to be sedentary, solitary and rare in those swamps. It is protected by law in Indonesia. This is a rare and remarkable, relatively large, carnivore, about which little is known, and the very existence of this species might be considered at risk if more were known about its distribution and abundance in Indonesia. Leopards (Panthera pardus melas) and leopard cats (Felis benghalensis) occur on Gunung Tukung Gede, but are not known to visit the swamp forest. The Javan warty pig (Sus verrucosus) is believed to occur in or near the edges of the swamp forest. It is endemic to Java and assessed as vulnerable by IUCN. The occurrence of several species of bats which have only been recorded on a few occasions in Java is interesting, but, in view of the lack of knowledge of the distribution and abundance of bats in Indonesia, is not entirely surprising. It may reflect the focus of biological surveys on the area of Rawa Danau and Gunung Tukung Gede rather than any restriction of the bat species to that area. The species in question are Macrogloss. It is acknowledged that bats such as Pteropus vampyrus play an important ecological role in the swamp forest, where fruits of trees such as figs are distributed by bats, and bats may be responsible for pollination of certain species in the swamp forest. Despite a number of surveys including the birds of Rawa Danau and Gunung Tukung Gede, the avian fauna is still the subject of much debate. Many of the bird species recorded from the area may be transient visitors. The 1993 report includes a compiled list of all 183 bird species recorded by various observers from the Rawa Danau and Gunung Tukung Gede areas as Appendix VI. The 1993 report also includes a table extracted from MacKinnon (1988) listing 23 bird species whose existence in the area is a basis for protection and conservation of the area. Most of these are categorised as rare or very rare in Java. Based on sightings in different habitats, 60 bird species were definitely recorded by observers in 1993 in swamp forest, and 31 species in reed swamp. Based on these reports this area has a very diverse bird population with numerous species which are rare and some which have only been recorded from Java on a few occasions. The 1993 report also lists species of reptiles, amphibia and fish which are known to occur in the area. It is very doubtful if these lists are complete. Conclusions as regards the fauna - The known distribution of the fauna from the area of Rawa Danau and Gunung Tukung Gede shows that the proximity to each other of these two areas of very different habitats has encouraged the existence of a very diverse fauna. It includes species of mammals and birds recorded from nowhere else in Java at the present day. This last substantial area of peat swamp forest in Java, although degraded, has acted as a refuge for several species which have been eliminated from other such areas. 6. Evaluation of the conservation status of the swamp forest The case for conservation lies in the data and information detailed above. Some of the tree species were probably quite widely distributed in Java. However, the demand for land for irrigation for rice production has led to the drainage of swamp forests elsewhere in Java. The possible survival of small fragments of four or five hectares of swamp forest near Jakarta, or on the south coast, has not been investigated in this project. The tree species which form the basis for discussion are listed above. It is noteworthy that one plant species is believed to be entirely restricted to the area of Rawa Danau. Many of the tree species which are restricted on Java to this area, are also reported to be found in swamp forest in Sumatra. There is little certainty that the species are identical, as the populations may have been separated for many thousands of years. Also, one has to note that the swamp forests in Sumatra are under threat from logging companies, from transmigration settlements, from casual destruction by illegal settlers, and from destruction by forest fires such as those raging in September and October 1997, in peat lands in Riau, Lampung, and Jambi. In these fires, it is not just the trees which are lost by burning, but the organic soil itself is burned, so the entire ecosystem, established over thousands of years, can be destroyed in one month. There is little information on the rate of change of the conservation status of the area. The descriptions of Endert (1932), van Steenis (1936), Biotrop (1986), Melisch et al. (1993), and Dir. Gen. PHPA (1993), may form a basis for such an assessment of the rate of change, though the large gap of 48 years from 1938 to 1986 is a major drawback. The evidence, such as it is, supports the probability that the actual area of swamp forest has decreased, and the quality of the swamp forest has decreased. There is no longer any large area of swamp forest with a closed canopy. The bird fauna of the area has been described by several investigators as has the mammalian fauna. There has been little effort to investigate the species of invertebrates, or vertebrates such as frogs and amphibians, which are found in the area. There appears to have been a steady decline in the diversity and abundance of the fauna over the last 60 years. Crocodiles, including perhaps Tomistoma, were once hunted in the swamp forest. They may well have been exterminated by hunting, despite the fact that the area is a Cagar Alam. The declaration of the area as a Cagar Alam appears to have had little or no deterrent effect on hunting activities. Fishing cats were recorded from the area, and from no other area of fresh water swamp in Java. They too may well have been wiped out. Thus, the case for conservation is not unequivocal. It can be argued that conservation to protect and maintain this ecosystem is now too late. It should have started 40 or 60 years ago, under a more effective management. Nevertheless, this ecosystem remains relatively intact though some large and noticeable species may have been lost. It has not, as far as is known, been subjected to fires consuming the peat soils like those which have affected swamp forests in Sumatra. It could be restored. It has the important virtue of being relatively isolated from the outside world by the rim of the caldera, which greatly limits road access. This also provides an area of hill forest which is to varied degrees under protection. This forest area could be included in any management program for the area of the caldera as a whole. The area retains a high potential for conservation of the swamp forest ecosystem, if given effective management. There has been massive destruction of conservation areas in West Java, despite their listing in the National Conservation Plan in 1982. It appears that about 30% of all conservation areas listed in that Plan no longer exist, having been clear felled for housing, industrial development, golf courses or agriculture. This process of destruction continues at the present time. It seems very appropriate to propose that this area, which is already designated as a conservation area of the highest importance, should remain as a conservation area for the foreseeable future. If it is to remain as a conservation area, and if it is to have any chance of survival, retaining its conservation values, then the present inappropriate and ineffective management policies must be altered. Recommendations 1. The conservation management of the area should be maintained and strengthened. 2. The area should remain as a Cagar Alam to maximise the chances of protection of vegetation and wildlife. 3. There is a need for a reassessment of the management of the area. 4. It may be necessary to bring the entire floor of the caldera under one management system in order to improve management of the swamp forest.
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