Tukirin Partomihardjo

The rebuilding of an isolated rain forestassemblage: how disharmonicis the flora of Krakatau?

The compositional balance of the flora of the Krakatau Islands, Indonesia, is examined in order to identify taxonomic and/or ecological groups which are under-represented in this recovering island ecosystem in relation to regional analogues and potential source areas in the Sunda Strait (Ujung Kulon and Sebesi Island). Interpretations are conditioned by the limited availability of comparative data, the uncertainty surrounding dispersal classifications, the problem of determining habitat suitability for missing elements, and thus the unsuitability of a formal statistical approach. Analysis by dispersal syndrome supports predictions that species with large, winged, wind-scattered propagules, or those with no particular dispersal potential, are under-sampled. However, some species with winged propagules have colonized, in most cases probably by thalassochory (sea-dispersal). Although zoochorous (animal-dispersed) trees and shrubs are well represented on Krakatau, those large-seeded species which are primarily dependent on dispersal by animals other than birds are under-represented. Large-seeded zoochores are probably highly dependent on two species of Ducula (large fruit-pigeons) for transport to Krakatau and their colonization has been relatively slow. Comparison with Christmas and Jarak Islands yields differing degrees of overlap for thalassochorous, zoochorous, and anemochorous (wind-dispersed) spermatophytes and for pteridophytes, interpretable in terms of dispersability and size of the respective species pools. Particular families and genera can be identified which are seemingly under-sampled on Krakatau, as can some which are over-represented in relation to the principal comparative site, the Ujung Kulon peninsular, West Java. The latter are mostly very small-seeded wind-dispersed epiphytic herbs (especially orchids). Ferns are also very well represented in relation to the West Javan source pool. It is concluded that the flora of Krakatau remains disharmonic, in a predictable fashion, although it is certainly becoming less so. The data provide empirical evidence for the abilities of particular functional guilds of rain forest plants to disperse across significant barriers: the implications of these findings are discussed in relation to current concerns with forest fragmentation in the tropics.

Ecological aspects of plant colonisation of the Krakatau Islands

Species assemblage data from the Krakatau Islands, Indonesia, are presented for the period 1883 to 1989 (including previously unpublished data from the 1989 survey). Since 1934, 16 additional families of higher plants have colonised. Recent arrivals at the family level are mostly of zoochorous species of forest tree, indicating (subject to the effects of disturbance) a continuing increase in potential niche space within the island interiors. The data for Rakata (an uninterrupted prisere) conform to a successional explanation in which identifiable ecological groups of plants exhibit differing colonization and turnover patterns. Animal-dispersed canopy tree species and species which are widespread within the group, exhibit a very low probability of extinction once they have colonized successfully. There are, however, several constraints on the rapid spread of species within the group, in particular those connected to local dispersal (eg lack of large terrestrial mammals). In respect of dispersal to the group, partial survey data for the island of Sebesi from 1921 (revised) and 1989 provides the basis for comment as to the changing biogeographical circumstances of the Sunda Straits and the role of Sebesi as a ‘stepping stone’ island.The varied data discussed in the paper indicates that with the exception of the strand-line, no component of the Krakatau flora or vegetation has yet approached a stable composition. Both floral and faunal diversification are argued to be proximally controlled not only by dispersal opportunities but also by the dynamics of the dominant life-forms of the system, ie, the forest trees. Such hierarchical links, across trophic boundaries, should receive greater recognition in the construction of island biogeographical theory.

Anak Krakatau's vegetation and flora circa 1991, with observations on a decade of development and change

Ecological surveys were conducted over the period 1989 to 1991 on the island of Anak Krakatau. The aims of the study were to detail a key phase of rapid change in the vegetation succession and plant colonization of this young volcano and to compare results with those from earlier studies.Floristic composition was determined by reconaissance of all vegetated areas during the period 1989 to 1991. Colonization has been rapid since 1983 with 53 species newly recorded for Anak Krakatau, comprising 8 Pteridophyta and 45 Angiospermae. Of the latter, a significant element (13) were of species believed to be human-dispersed. Comparison of all floral surveys has revealed a core of strand-line and pioneer colonists which has been common to each restart of colonization. The sea-dispersed component is already comparable in size to that of Rakata and is thought unlikely to increase significantly from this point. The accumulation of animal-dispersed species of interior habitats has only recently begun to pick up speed.Vegetation was characterised by means of plot-based sampling, including the establishment of three permanent plots, and by mapping at the whole-island scale. Variation in composition within the island is discussed, with particular reference to the three vegetated “forelands”. Anak Krakatau now supports the most extensive and advanced vegetation in its disrupted 61-year history. A more or less closed cover extends along the eastern/north-eastern coast-line, but the xeric interior remains only sparsely vegetated. It is concluded that because of volcanic disturbance a base-line for ecosystem development on Anak Krakatau cannot be calculated but that the pattern of change is not inconsistent with significant disturbance ca. 1972 and the subsequent relaxation of these peculiar environmental constraints.

Dynamic steady state of patch-mosaic tree size structure of a mixed dipterocarp forest regulated by local crowding

A patch age- and tree size-structured simulator was applied to demonstrate the landscape dynamics of a lowland mixed dipterocarp forest, using census data over a 3 year interval from two 1 ha plots in northern West Kalimantan, Indonesia (Western Borneo). Tree growth rate and recruitment rate were estimated as functions of tree size and local crowding. The effect of local crowding was assumed to be one-sided through light competition, where the basal area for all trees larger than a target tree inside the circle of 10 m radius around the target was employed as the index of crowding. Estimated parameters were similar between the two plots. Tree mortality was expressed by descending function of tree size with asymptotic mortality for large trees corresponding to the gap formation rate. One parameter specifying the survival of trees at gap formation, which was required for the landscape-level simulation of a shifting-gap mosaic, was left undetermined from plot census data. Through simulation, this parameter was estimated so as to best fit the observed among-patch variation in terms of local basal area. The overall time course of simulation and tree size structure were not sensitive to this parameter, suggesting that one-sided competition along the vertical forest profile is a stronger determinant of average forest structure than among-patch horizontal heterogeneity in this forest. Simulated dynamic steady state successfully reproduced the observed forest architecture in the gap-dynamic landscape. It took about 400 years for a vacant landscape to be replaced by a steady-state architecture of forest. Sensitivity analysis suggests that steady-state basal area and biomass are most sensitive to changing gap formation rate and intrinsic size growth rate.

Forest development on Rakata, Panjang and Sertung: Contemporary dynamics (1979–1989)

Ten years of quantitative studies of forests on Krakatau demonstrate the vegetational difference resulting from multiple successional pathways. Multivariate analysis of the forest data indicates strong statistical separation of forest types within and between the islands. Current rates of forest growth and change within the Krakatau islands are found to vary considerably. The canopy architecture of Panjang and Sertung is observed to have changed dramatically over the past six years while the pace of change on Rakata appears relatively slow, particularly in the uplands. In an area studied in near-coastal, lowland Rakata, seedling recruitment of Neonauclea calycina is poor and its continued status as an overwhelmingly dominant species must be in question. A slightly more diverse forest appears to be developing below about 120 m elevation, in which Dysoxylum gaudichaudianum is an increasingly important component. Disturbance phenomena, ranging from continuing volcanism to individual tree falls, are found to be critical to an understanding of forest development on the islands. Despite the increasing role of Dysoxylum on Rakata our data indicate a continuing divergence of compositional types within the lowland forest.

The processes that threaten Indonesian plants

The processes that threaten 240 Indonesian threatened plants were identified and categorized based on a comprehensive review of the published literature and elicitation of information from experts. Intrinsic biological factors and habitat loss are the major causes of plant endangerment in Indonesia (affecting 83 and 82 of species respectively), followed by overexploitation (64) and natural factors (6). The dominant threats vary between major plant groups, with habitat loss being particularly important for palms and trees, and biological factors important for orchids. For all studied plant species three sets of inter-related threatening processes (threat syndromes) were identified that differed among the major plant groups. By identifying and evaluating the processes that threaten plants in Indonesia we provide knowledge to guide their future conservation. © 2011 Fauna & Flora International.

DISTRIBUSI VERTIKAL DAN HORIZONTAL Asplenium nidus L. DI TAMAN NASIONAL GUNUNG HALIMUN, JAWA BARAT [Vertical and Horizontal Distributions of Asplenium nidus L. in Gunung Halimun National Park, West Java]

Studi taksonomi jamur di Taman Nasional Gunung Halimun (TNGH) belum dilakukan dengan intensif.Sebanyak 35 jenis Agarics dikoleksi dari kawasan TNGH meliputi 23 marga dan 9 suku.Kekayaan keanekaragaman jamur ini diperoleh dari eksplorasi di 3 lokasi yaitu Cikaniki, Gunung Botol dan Gunung Telaga (Ciptarasa).Sejumlah sampel belum teridentifikasi karena karakter yang belum jelas.Oleh karena itu, jumlah jenis-jenis baru dari eksplorasi ini belum dapat diketahui.Fifty strains of Bacillus sp. isolated from Gunung Halimun National Park (GHNP) were characterized. All strains are characterized by amylase, protease, phosphatase, ligninase, and cellulase activity.Thirtyseven isolates gave positive reaction for amylase activity, 46 isolates for protease activity, 3 isolates for phosphatase activity, 3 isolates for ligninase activity, and 36 isolates for cellulose activity.These findings indicates that Bacillus sp. that isolated from GHNP is a potential microbe for enzymes technology and biotechnology application.Fish fauna survey were conducted in Cimadur, Ciujung and Ciberang Rivers. From these studies six fishes species were found as additional record for fishes living in Gunung Halimun National Park and its adjacent area. This finding brings the fish species living at this park to be sixty.In this record, it includes Cypriniid fishes that attain large size: Barbodes balleroides and Osteochilus hasseltii, found in the segment of the middle of R. Ciujung (18.3 m asl).The fieldworks for inventory and collection on mammals in Gunung Halimun National Park (OHNP) had been carried out for long time; however the works only focused on the areas belong to Bogor District. Therefore, the fieldwork was carried out in the buffer zone of the GHNP in Lebak District.The fieldwork had collected 70 numbers consisted of 16 species of mammals, of which five species were new records for GHNP and of those five species, two species (Glischropus javanus and Myotis sp.)were new collection for the Museum Zoologicum Bogoriense-Research Center for Biology-The Indonesian Institute of Sciences (LIPI).The Baduy people were noticed to hunt fruit-bats from some caves for their food.It was suggested a monitoring activity on the utilization of fruit-bats should be conducted for the conservation of the fruit-bats.Further fieldwork outside the Bogor District in the future should also be considered, particularly on the area along the river.