Flora and vegetation

Floristically, Java and Kalimantan are among of the richest sites on earth. Taxa from East Asian and Austral-Antarctic floristic regions can be found in mountains, while Indo-Malaysian elements are reviling and are rich in species in the hot lower altitudes (e.g. Dipterocarpaceae), East Asiatic taxa (e.g. Fagaceae) progressively become more diversified upslope to mid altitudes. Austral-Antarctic taxa (e.g. Ranunculus, Dacrycarpus, and Leptospermum) are found at higher elevations (Hotta, 1974).

Forest types of the area include mangroves, peat swamp and freshwater swamp forests, extensive heath forests, lowland dipterocarp forests, ironwood, forests on limestone and ultrabasic soils, hill forest and various montane formations (e.g. Flenley, 1979; Whitten et al., 1996; Collins et al., 1991) (Fig. 1.5). Other plant communities are represented by beach vegetation, grassy shrublands, grasslands, estates and agricultural ecosystems (MacKinnon et al., 1997).

35 The vegetation of Java can be classified in a number of different ways (Campion and Seth, 1968;

Whitmore, 1984; MacKinnon et al., 1982; MacKinnon and MacKinnon, 1986; Whitten et al., 1996).

Natural forests include several forest subtypes, i.e. extensive evergreen rainforest (monsoon forest), semi-evergreen rainforest, moist deciduous forest along the northern coast, and dry deciduous forest. The differences are mostly related to the seasonality of rainfall. No single tree family dominates the forests of Java, as is the case with the dipterocarps in Kalimantan (Whitten et al., 1996). The most common species in the rainforests of Java are Artocarpus elasticus (Moraceae), Dysoxylum caulostachyum (Meliaceae), Lansium domesticum (Meliaceae) and Planchonia valida (Lecythidaceae). Semi-evergreen rain forest differs from evergreen rain forest by being slightly more seasonal, with two to four dry months each year (Whitten et al., 1996).

Java's deciduous forests generally are lightly closed, with few trees exceeding 25 m. Borassus and Corypha palms are good indicators of the seasonal climates that generate deciduous forests in the region. Moist deciduous forests have 1500 to 4000 mm of rainfall annually, with a four- to six-month dry season. Dry deciduous forests have less than 1500 mm of annual rainfall and more than six dry months. Common lowland deciduous trees found in eastern Java and Bali are Homalium tomentosum, Albizia lebbekoides, Acacia leucophloea, A. tomentosa, Bauhinia malabarica, Cassia fistula, Dillenia pentagyna, Tetrameles nudiflora, Ailanthus integrifolia, and Phyllanthus emblica.

Many herbaceous plants are confined to the deciduous forests (Whitten et al., 1996). Patches of freshwater swamp forest found throughout the ecoregion are relatively poor in species (Whitten et al., 1996). Rawa Danau, Banten in west Java is the largest remaining area of swamp forest in Java and Bali, and it contains many tree species now nearly extinct elsewhere in Java, such as Elaeocarpus macrocerus, Alstonia spathulata, wild mango (Mangifera gedebe) and Stemonurus secundiflora.

According to Stuijts (1993) and Stuijts et al. (1988), mountain vegetation of Java has a distinct belt structure and can be described it is shown at the scheme (Fig. 1.4). Submontane forest is closed, with little moss and poor ground flora. It is represented by seasonal mountain forest, growing above 1000-1400 m following evergreen or semi-evegreen forest, and mountain aseasonal forest, at the same elevation above monsoon forest. Common trees are Celtis, Altingia and Myrtaceae. Lower montane forest differs from the previous forest type by very rich ground flora and lower number of tree species. It is observed at the level of 1400-1800 m. This zone is often caller ‘Lauro-fagaceous belt’ as Castanoptis together with Quercus and Lauraceae predominant. Many lowland families no longer appear (Backer et al., 1963, 1968), more temperate genera, including Lonicera, Nertera, Gaultheria appear (Whitmore, 1975). Mountain vegetation is upper mountain forest growing at the elevation of 1800-2400 m is described as closed, high-stem, floristically rich mossy mesophyll forest with Podocarpus, Dacrycarpus, Engelhardia being characteristic trees. Ericoid montane forest can be

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found on the level of 2400-3000 m. It is mossy microphyll forest, consisting of a single low canopy with rich ground flora and few lianas. Device Ericaceae, Rapanea and on volcanic soils Myrica can be found there. Subalpine ericoid scrub appeared when elevation riches 3000-3600 m. Herbs and low microphyll shrubs, dwarf forms of trees found in below vegetation are recognized there. In the uppermost sites alpine rock-desert occurs.

Fig. 1.6. Vertical zonation of Javanese (based on Stuijts, 1993 and Stuijts et al., 1988) and Kalimantan (based on Whitmore, 1984a and MacKinnon et al., 1997) mountains with the characteristic taxa and vegetation belts.

The vegetation of Java has been strongly changed by humans during the last few hundred years. Over the half the original area has been turned into grassy shrubland with Trema, Malotus, Melastoma, Lantana, and Eupatorium. Extensive palm plantations and rice fields as well as abandoned estates and aquaculture land occupy nowadays large territories. Strongly reduced area of mangroves is now limited to the stands along the northern coasts of Java (e.g. around Ujung Kulon), in Segara Anakan lagoon (White et al., 1989; Yani et al., 2004; Hinrichs, 2006; Noor et al., 2006; Hinrichs, et al., 2009;

Geist, 2007, Geist et al., 2012;) and in Grajagan Bay, Segoro Anak (White et al., 1989; Whitten et al, 1996). The most important families in mangrove forest of Northern Java are Rhizophoraceae with Rhizophora, Bruguiera, Ceriops followed by Avicenniaceae (Avicennia) and Sonneratiaceae (Sonneratia).

Kalimantan supports some of the largest expanses of tropical rainforest is SE Asia, providing some of the most spices-rich habitat on earth. Most of Kalimantan is covered by species-rich closed-canopy forests with high endemism (e.g. Whitmore, 1984; Jacobs, 1988; MacKinnon et al., 1997) very high productivity (Ashton, 1982; MacKinnon et al., 1997), long history (Muller, 1970) and a great diversity;

there are as many as 240 different species of trees growing within a hectare (Kartawinata et al.,

37 1981; Ashton, 1989). Main types of lowland rainforest of southern Kalimantan are Dipterocarp forest, heath forest (Kerangas), ironwood forests predominating by Eusideroxylon zageri as well as forests on limestones and ultrabasic rocks. The general characteristics of these forests are canopies 24-36 m high with emergents reaching up to 65 m. Dipterocarpaceae is a dominant family in the emergent stratum. In the richest forests, up to 80% of the emergent trees are dipterocarps: Dipterocarpus, Dryobalanops, Shorea, Hopea and Vatica together with species from Berseraceae and Sapotaceae are usually found in the main canopy as well. A third layer occurs below the canopy of shade-tolerant species, adorned with lianas, orchids, and epiphytic ferns. This layer includes many species from the Euphorbiaceae, Rubiaceae, Annonaceae, Lauraceae, and Myristicaceae families. In some cases Euphorbiaceae is more common than dipterocarps, being the second most common family in Kalimantan. On the forest floor, herbs, seedlings, and shade-tolerant palms exploit the few places that receive sunlight.

In mountains of Kalimantan Whitmore (1984) described five altitudinal floristic zones (Fig. 1.6). These are already described lowland dipterocarp zone (less than 300 m), the hill dipterocarp zone (300-800 m), the upper dipterocarp zone (800-1200 m), the oak-chestnut zone with Fagaceae and Lauraceae predominant (1200-1500 m), and the montane ericaceous zone (higher than 1500 m). Upper montane forests share many species and features of the structure and appearance with heath forests (Eugenia, Rhododendron, Vaccinium), yet none of the heath forest dipterocarps expends above 1,500 m. Only few plants span the complete altitudinal range from lowlands to upper montane forest, e.g.

Dacrydium (MacKinnon et al., 1997). The highest altitudes of Southern Kalimantan bare closed-canopy scrubs.

Mangroves fringe most of Kalimantan coastline. They occur almost in all bays and lagoons, along the deltas of major rivers, with particularly extensive stands at mouths of the Kapuas, Mahakam and Sebuku. The most important taxa in mangroves of Southern Kalimantan are Rhizophora, Bruguiera and Xilocarpus. In older stands they may be an understory of Ceriops tagal (Soegiarto and Polunin, 1980). Sonneratia alba, Avicennia alba and A. marina and are important for pioneer communities.

Dryer areas are colonised by Bruguera, Lumnitzera, Aegiceras, Exocoecaria, and Osbornia. Acantus ilicifolius can appear along the edge of estuarine mangroves. Along tidal rivers Sonneratia caseolaris grows. Stands of Nypa fruticans, only mangrove palm, flourish inland, along tidal creeks and estuaries; a few leans may occur (e.g. Derris), and ferns, grasses and sedges sometimes colonise openings (Chapman, 1977). In sites where mangroves have been disturbed, the giant fern Acrostichum aureum may form dense undergrowth, so thick that the mangrove trees cannot regenerate. Main agricultural landscapes of the Kalimantan are oil palm plantations with minor rice field development compare to Java.

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