Towards a Geobotanical Insight into Vegetation Adaptation in Quaternary Mud Volcanoes: Java Island, Indonesia

Abstract

Since the Lusi eruption in 2006, interest in studying mud volcanoes in Indonesia has significantly increased, with most research focusing on the onshore Northeast Java Basin (Kendeng and Rembang Zone), yet comprehensive studies on the vegetation surrounding these mud volcanoes, particularly from a geobotanical perspective, are lacking. This study aims to document and analyze the vegetation around various 18 mud volcanoes in Java Island, Indonesia and explore its relationship with the geological characteristics of the volcanoes. Through field mapping and site visits to all identified 18 mud volcanoes on Java and Madura Island, samples of mud and vegetation were collected for detailed laboratory analysis. By examining the vegetation that grows at the center and the periphery of the mud volcanoes, a relationship between vegetation composition and the mud volcanoes in Java Island, Indonesia, can be identified. It becomes more interesting as saline substrates play a key role in their adaptation. The vegetation surrounding quaternary mud volcanoes in Java Island is significantly influenced by the characteristics of the erupted mud material. Plants from the families Poaceae, Fabaceae, Asteraceae, Cyperaceae, and Euphorbiaceae are well-adapted to the vicinity of mud volcanoes in both the Kendeng zone, rich in marl from the Kalibeng formation, and the Rembang zone, rich in clay. These plants can thrive and adapt to substrates with distinctive chemical characteristics, such as high salinity levels (>10%) and dominant calcium and magnesium content (30–60%). This research indicates a complex interplay between geological factors and plant species distribution in the unique environment of mud volcanoes. This research is expected to inspire further studies on this unique geological feature and advance the field of geobotanical study.