Study site
A field study was performed in the dry evergreen forest (DEF) at Sakaerat Environmental Research Station (SERS) (14°30´N, 101°56´E; about 500 m above sea level) in Nakhon Ratchasima Province, northeastern Thailand (Fig 1). According to SERS meteorological stations from 2005 to 2015, the mean annual rainfall was 1,084 mm with monthly rainfall less than 40 mm during the dry season from November to April and the wet season started from May to October. The average annual relative humidity and temperature were 83.8% and 26.7°C (9.1-38.9°C), respectively. During the study, the monthly rainfall, temperature, and relative humidity were 189 mm, 25.1°C, and 74.4%, respectively in October 2015 (wet season) and 12.1 mm, 23.7°C, and 71.0%, respectively in January 2016 (dry season). The DEF covers an area of 29.5 km2, where the dominant tree species are Hopea ferrea and Hopea odorata with canopy trees reach generally 23 to 40 m (Lamotte et al., 1998).