Challenges of an Island Ecosystem

Vegetation
Vegetation A. Kühlem
Endemic Bikkia palauensis
Endemic Bikkia palauensis A. Kühlem

The Palau Islands, like many other islands in Oceania, are very isolated and far from larger land masses. This explains the low biodiversity and, at the same time, a comparably high level of endemism. This is especially true for the vegetation of the geologically young volcanic islands. Only a few seeds are transported over such long distances by ocean currents - and are still fertile after weeks or months in salt water. The distances between the island groups are too great for the wind to spread seeds. Even seabirds can only transport seeds to the islands to a very limited extent in their plumage.

While the reefs around many of the islands have an abundance of fish and marine mammals and there are a number of endemic land birds, the biodiversity of land animals on the widely scattered islands is extremely low. The only mammals before human arrival were species of bats that could traverse the distance between the islands on the wing. The human factor, however, profoundly changed the biodiversity of the islands.

Endemic fruit dove
Endemic fruit dove A. Kühlem

As on all islands in Oceania, in Palau the land fall by the first Austronesian settlers had far-reaching effects on the ecosystem. In the beginning the newcomers had to adapt to the prevailing environmental conditions, but gradually they began to change their environment and optimize it for their needs.

While the majority of the approx. 445 Palau Islands are small karst islets (locally known as rock islands), the largest island, Babeldaob, is of volcanic origin. The topography here is characterized by densely forested hills with deep-cut valleys and a mangrove belt in the littoral areas. Babeldaob is almost completely surrounded by a coral reef. Along the east coast the reef is only a few hundred meters from the coast, in the west it is a few kilometers. On the eastern side, the reef flat is so shallow that it is almost completely dry at low tide.

 

Rock Islands

Rock Islands
A. Kühlem

blind_2020_15
Deep-cut valley in Ngeremlengui
Deep-cut valley in Ngeremlengui D. Schäffler
blind_2020_15
The eastern shore of Babeldaob during low tide
The eastern shore of Babeldaob during low tide D. Schäffler

 

Introduction
Challenges of an Island Ecosystem
The human factor
The monumental earthworks of Babeldaob
The first contact with the outside world
Brief history and state of research
Open questions
Geoarchaeological and archaeological research
Involvement of the local population
Project data