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Plants of Bali

The great Victorian naturalist, A.R. Wallace, who visited these islands in the mid-19th century, noted that there was something special about the position of Bali. Looking at the island's animal life, and comparing it with that of neighboring areas, he observed a startling difference between the faunal composition of Bali and the island of Lombok just to the east, despite the fact that the two are separated only by a narrow strait 40 kilometres wide. Wallace therefore concluded that this strait marks a division between two of the world's great biogeographic realms, the Asian and the Australian. He tracked this dividing line, which came to be known as Wallace's Line, farther northwards between Borneo and Sulawesi, and thence to the strait separating Sulawesi from the Philippines.

As it turns out, Wallace's Line traces the edge of the huge Sunda continental shelf, which has Bali as its southeastern outpost. Much of the Sunda shelf is now submerged under the South China Sea, but at several periods in the past it was exposed and what are now the islands of Sumatra, Java, Borneo and Bali were connected to the Asian mainland by land bridges.

Bali's flora, therefore, has far stronger connections with the west than the east; it is effectively a reduced version of Java's flora, which is itself poorer in species than the islands of Borneo and Sumatra. "Impoverished" is, however, a relative term, for there are at least 4,500 native plant species found on Bali.

Bali's Shrinking Forests

So pervasive has mankind's influence been on the landscape of Bali in the last 4,000 years that it is extremely difficult to determine what the vegetation of the island looked like before man's arrival. When the island first emerged from the seas, it found itself in a biologically rich region of tropical forest flora, a ready source of vegetation for the newly emerged volcanic landscape.

It seems that at the end of the last ice age around 8,000 years ago, Bali was covered in various forms of forest, both evergreen and deciduous, although vegetation high on the volcanoes above the tree line was very limited in extent. Ecologists have classified Bali's forests into six major types, although in practice it is impossible to actually see where one type begins and another ends. The types of forest are: evergreen rain forest, semi-evergreen rain forest moist deciduous forest, dry deciduous forest, seasonal montane forest and a seasonal montane forest.

Bali's mangrove forests are now reduced to about five square kilometres; this patch is south of the airport, flanking the road to Nusa Dua.

This hardy, salt-resistant plant is one of the several types of Pandanus (screwpine) which thrive along Bali's beaches.

Staghorn Ferns (Platycerium coronarium) grow wild on tree trunks and branches.

The intense crowding of vegetation in a patch of rainforest completely obscures the soil; even the trees are covered with mosses, Bird's Nest Ferns (Asplenium nidus) and other creepers.

A close-up view of ferns in the rainforest.

Moist deciduous or monsoonal forest was originally the most common form of vegetation, covering an estimated 43% of the island, including most of the central uplands. This is scarcely surprising, given the wet but highly seasonal nature of Bali's climate. The moist deciduous forest, along with virtually all other forest types on Bali, has been drastically reduced in extent.

Straddling the border between the land and the sea are man-grove forests, mainly growing in tidal flats around Benoa Bay Many have now been reclaimed and only around 5 square km of mangrove forest still exist on Bali; it is quite likely that they were never very extensive. Bali's sandy beaches are dominated by the purple-flowered Morning Glory (Ipomoea pescaprae) along with other creeping plants which help to stabilise the sand. In some areas, the shoreline forests are dominated by Barringtonia asiatica and Screwpine (Pandanus tectorius), Yellow Beach Hibiscus (Hibiscus tiliaceus), Cycads (Cycas rumphii) and other salt-tolerant species.

Lowland forests were formerly common in most inland areas. The limestone forests of the southern coasts are almost entirely cleared or degraded, and most of the area is now scrub dominated by introduced plants such as Lantana and the composite Chromolaena (formerly known as Eupatorium).