The study of floral diversity in forest and its development are incomplete without taking consideration of plant-soil interactions. So with this view in mind, the present study was conducted in tropical semi-evergreen forests of the Mokukchung district, Nagaland, in eastern Himalaya. The aim of the study was to investigate the phytosociological parameters in relation to soil properties.Seven sites were randomly selected to study the soil properties at up to one meter in depth and a phytosociological study was carried out in nearby areas via the quadrate method. In the studied sites, the richness of tree species varied from 4 to 15 ha, with Gmelina arborea and Duabanga grandifloras being the common species.The highest total basal area was recorded in 10 mile village(47,998.16 cm~2ha~-1)) followed by Minkong village site(32,704.66 cm~2ha). Soil physical and chemical properties—i.e. bulk density(BD), soil p H, organic carbon(OC),available nitrogen(N), available phosphorus(P), and available potassium(K) were analyzed using standard procedures. Significant differences were observed in the soil properties. The basal area of species showed significant positive correlation in terms of available K(0.754) and OM(0.302) content in soil, and the Shannon–Wiener diversity index(H) is also positively correlated with the available N content(0.402). The undisturbed nature of the sites played an important role in maintaining the soil fertility and floral diversity of the sites. Moreover, sites with maximum productivity and soil fertility are considered as potential carbon sequestration areas in the region while sites with the low soil fertility need restoration.
