Seasonal variation of soil moisture in dry dipterocarp forest on sandstone and volcanic rock at Huai Hong Khrai Royal Development Study Center, Chiang Mai Province

Abstract

This research aims to compare seasonal variation of soil moisture conditions in dry dipterocarp forest between sandstone and volcanic rock areas. Soil sampling was carried out along soil depth in each area, 3 pits (3 replications) with one time per month (January to December 2018). The soil samples were analyzed for physical properties, moisture content and field water capacity. In sandstone area, the soil was classified into Order Inceptisols: shallow soil (40 cm) with many rock and gravel containing soil particle. Soil on volcanic rock was Order Oxisols: very deep soil (>2 m) with fine texture (clay) and almost no gravel. The sandstone soil had lower moisture status than the volcanic rock. Maximum water holding capacity in soils of sandstone and volcanic rock were measured as 202.96 and 790.48 m³/rai, respectively. In dry season especially February, the moisture content was very low (1-3% by weight) in sandstone soil while the volcanic rock soil contained 16-30%. The different moisture condition is important factor of lower plant species richness in the dry dipterocarp forest on sandstone area compared to the volcanic rock.