Aspects of nutrient cycling and nutrient use pattern of Bhabar Shisham forests in central Himalaya, India

Abstract

This paper illustrates the nutrient related variables such as storage, uptake, nutrient use efficiency (NUE) and nutrient cycling in 5–15 years old Dalbergia sissoo Roxb. forests growing in Bhabar belt (a nutrient poor and low water table site) in central Himalaya previously studied for biomass and productivity. The percent nutrient concentration and nutrient storage in vegetation is in order: trees>shrubs>herbs. However, different strata accounted in order: soil (80–92%)>vegetation (7–18%)>litter (1–1.5%). The nutrient retranslocation in leaves of different vegetation layer was in order: trees (29–44%)>shrubs (27–35%)>herbs (17–23%). The nutrient uptake, i.e. gross and net by trees, shrubs, herbs and total vegetation was studied. The total nutrient transfer through litter inputs to the soil was 71–90 N kg ha −1 per year, 5–7 P kg ha −1 per year and 43–47 K kg ha −1 per year. The turnover rate and turnover time of litter nutrients (NPK) ranged from 57 to 60% and 1.6–1.8 years, respectively. The turnover rate indicates that about 60% litter nutrient release on the forest floor, which showed that the litter nutrients are also equally important for the nutrient cycling as the other aspects such as retranslocation and uptake. The NUE in Shisham forests ranged from 140 to 150 N kg ha −1 per year, 1560–1769 P kg ha −1 per year and 340–345 K kg ha −1 per year. Compared with the Tarai Shisham forests, exotic plantations (eucalypt and poplar) and central Himalayan natural forests. It is concluded that Bhabar Shisham forests have shown better nutrient conservation efficiency than those of Tarai Shisham forests. For nutrient dynamics compartment graphs represent the distribution of nutrient pools and net annual fluxes of the investigated forest ecosystems.