| 要旨トップ | 本企画の概要 | | 日本生態学会第73回全国大会 (2026年3月、京都) 講演要旨 ESJ73 Abstract

シンポジウム S07-1 （Presentation in Symposium）

#### Seasonally dry tropical forests in the world and Madagascar: why they should be conserved as natural heritage【E】

*Kaoru KITAJIMA（Kyoto Univ.）, Hiroki SATO（Kyoto Univ.）, Tomohiro NISHIGAKI（JIRCAS）

This presentation will give the background and an overview of the symposium today, in which speakers showcase a diverse range of ecological studies conducted in Ankarafantsika National Park, NW Madagascar. Madagascar is famous for its unique biodiversity, with a high level of plant and animal endemism, many of which evolved in forest ecosystems. Being the world’s fourth-largest island, separated from the African continent ca. 88 million years ago, and relatively recently colonized by Homo sapiens compared to other tropical landmasses, Madagascar is one of the most significant natural heritage sites. Unfortunately, population growth and poverty in recent years have led to a rapid loss of natural forests over the past 60 years, with the largest losses occurring in NW Madagascar, where rainfall seasonality is strong. Ankarafantsika National Park, which holds the largest area of natural forests in NW Madagascar, is acutely threatened by recurrent wildfires started by people. For the conservation of the seasonally dry forests of NW Madagascar, it is important to consider the implications of the dominance of sedimentary substrates in the region, which have been above sea level at least since the Jurassic. They include coarse white sand, a hardened lateritic, iron-rich layer, and reddish or yellowish sand, all of which are extremely infertile. The woody plants that form natural forests exhibit adaptations to soil nutrient limitations and seasonal drought, showing unique spatial patterns of community assembly. But, studies on soil-plant interactions, plant functional traits, and ecophysiological adaptations are just starting. Unlike tropical seasonal dry forests and savannas in other tropical regions, evergreen-dominated forests in NW Madagascar may lack adaptation to fire. This seasonally dry forest hosts a remarkable diversity of terrestrial vertebrates, but only a limited number of studies have examined plant-animal interactions in NW Madagascar that evolved independently of Africa and Asia. Humans have been modifying this landscape, including those who settled before the protected area was established in 1927. Residents permitted to live within the protected area have traditional ecological knowledge for using natural resources, but sustainable natural resource management is becoming increasingly difficult due to population growth, partly driven by nomadic immigrants from the semi-desert region in SW Madagascar. It is important to have an integrative understanding of the geology, biodiversity, and ecosystems to design strategies grounded in scientific evidence, to inform multiple stakeholders involved in conserving the remarkable natural heritage remaining in NW Madagascar.

日本生態学会