Plant Communities, Soil Characteristics and Nutrient Storages in Fragmented Lower Montane Forests, Sa Moeng District, Chiang Mai Province

Abstract

Soil physico-chemical properties and nutrient contents under the fragmented lower montane forests were studied at Boakaew watershed station, Samoeng district, Chiang Mai province. Five fragmented forests were randomly selected. In each forest, one sampling plot with the size of 40 x 40 m² was used for vegetation survey. Every tree growth which was higher than 1.5 m was measured. A soil pit was made in each fragmented forest, soil sampling and analysis for physico-chemical properties were conducted along the soil profile. It was found that plant communities were different among the forests. Dominant tree species were mainly Pinus kesiya, Castanopsis acuminatissima, C. diversifolia and Schima wallichii. Bulk densities of the top soils of every forests were low and had coarse texture which were sandy loam whereas subsoils were sandy clay loam, loam and clay loam. The 2^nd fragmented forest had sandy clay loam in top soil and clay to clay loam in subsoil.  Most top soils were strongly acid while subsoils were moderately to strongly acid. Organic matter contents were very high in most top soils, whilst the total nitrogen were varied. The contents of available P were medium to moderately high in top soils. The extractable K were high but extractable Na were low throughout the profiles of all forests. Extractable Ca and Mg were medium to low. Amounts of organic matter, carbon and nitrogen contents within 160 cm soil depth were varied between 164.0-476.6, 95.1-276.5 Mg/ha and 9,048-19,845 kg/ha, respectively, whilst, the amounts of OM, C and N were the lowest in the 2^nd fragmented forest.