Distribution and Conservation Status of Water onion (Crinum thaianum J. Schulze) in Thailand

Abstract

The objectives of study on distribution and conservation status of Water onion (Crinum thaianum J. Schulze) in Thailand were to investigated the extent of occurrence and to assess the conservation status of Crinum thaianum in Thailand according to the IUCN red list categories and Criteria version 3.1. The specially explicit distribution model, by Maximum entropy (MaxEnt), was used to predict its extent in the landscape and geographic information system was employed to generate the distribution map of Crinum thaianum.

The result revealed that the distribution of Crinum thaianum produced by MaxEnt had overall prediction accuracy of 94% and its extent of occurrence covered approximately 126 km². There were six environment a factors contributing to distribution of Crinum thaianum, including 1) annual precipitation (3,100-3,300 mm.), 2) mean temperature of driest quarter (27.5-28.5^oC), 3) maximum temperature of warmest month (33.5-34^oC), 4) elevation above mean sea level (0-30 m.), 5) soil group (deposition of allvuvium in river levee. Surface soil consisting of loam or silty sandy loam soil pH of 5.5-6.0 subsoil consisting of clay loam or silty clay loam and pH is 5.5-7.0, 6) landuse type (evergreen forest and partially in agriculture associated with urban area) According to previous studies and the current research, the distribution of Crinum thaianum is also continuing decline and shows extreme fluctuation. Therefore, Crinum thaianum is categorized as endangered status.