This research aimed to compare the water storage in the dry dipterocarp forest (DDF) at two sites located in Chiang Mai province, northern Thailand. Vegetation survey was carried
out in the forest using a 40 × 40 m2 plot, with 12 and 15 plots in Site 1 and Site 2, respectively. Plant data were obtained by measuring the stem girths at 1.3 m above ground and heights of trees with a height greater than1.5 m. Plant characteristics, biomass, and stored amounts of water were measured. The DDF at Site 1 was divided into four stands based on the most dominant tree species, which were Shorea obtusa, Shorea siamensis, Dipterocapus obtusifolius, and Dipterocarpus tuberculatus. The DDF composed of 60 species (50 genera and 31 families) and had a plant biomass of 91.99±11.44 Mg ha−1, with 100.70±9.91 m3 ha−1 as the contained amount
of water. The maximum water holding capacity (MWHC) of the soil was estimated to be about 1,837.21±96.35 m3 ha−1. The amount of water in the soil during the winter (December 23, 2015) and the rainy season (July 26, 2016) was estimated at 330.83±102.37 m3 ha−1 (18.0% of MWHC) and 1,072.46±18.93 m3 ha−1 (58.37%), respectively. The DDF at Site 2 was composed of five stands, which included the Pinus merkusii stand. Its species richness (83 species, 69 genera, 42 families), plant biomass (125.49±53.61 Mg ha−1), and amount of water (124.55±45.40 m3 ha−1) was higher than that of Site 1. The soil under the D. obtusifolius stand was deep and was able to
store the maximum amount of water at 4,981.57±132 m3 ha−1, with the amount of water at the end of the rainy season (October 12, 2014) calculated to be around 783.58±21.00 m3 ha−1 (15.72%). Thus, the DDF at Site 1 had a lower potential for water storage than the DDF at Site 2.