Fine root production and nutrient dynamics in relation to stand characteristics of chir pine mixed banj oak forests in central Himalaya

Abstract

Stand density and basal area are considered to be an important indicator of aboveground as well as belowground dynamics in forests. To understand the relationship between stand characteristics and fine root dynamics of chir pine (Pinus roxburghii) mixed banj oak (Quercus leucotrichophora) forests in central Himalaya we studied fine root mass, productivity, turnover rate and nutrient dynamics. Four sites were selected on the basis of increasing density and basal area of trees. From each site, ten random fine root samples were collected for one year by sequential coring method, using root corer of 8.0 cm diameter from three depths (0–10, 10–20 and 20–30 cm) on a monthly basis. Total mean fine root mass varied from 2.15 to 3.12 Mg ha−1, with biomass and necromass varying from 1.48 to 1.93 Mg ha−1 and 0.67 to 1.18 Mg ha−1, respectively. In terms of vertical distribution, values of both biomass and necromass decreased with increasing soil depth. Productivity was estimated between 1.24 and 1.51 Mg ha−1 y−1 while turnover rate varied from 0.78 to 0.84 y−1 throughout the sites. Concentration of nitrogen was found higher in live fine roots whereas, phosphorus, potassium and calcium did not show any significant variation between live and dead fine roots. In the present study, higher fine root mass upon increase in density and basal area of trees suggests that stand characteristics positively correlate with fine root mass while nutrient dynamics remain unaffected by stand characteristics as well as seasonal changes.