Carbon storage and sequestration in bamboo-based smallholder homegardens of Barak Valley, Assam.

Smallholder farming systems throughout the world are believed to be potential sinks to remove atmospheric CO2. Smallholder bamboo farming system in Barak Valley, Assam, which forms a part of the traditional homegarden system, holds promise in this respect. Occurrence of bamboo in all homesteads coupled with progressive increase in culm density over the years reflects its potential for carbon (C) storage. Hundred homegardens were selected from the study site and the total number of culms from all the different age classes per clump of Bambusa cacharensis, Bambusa vulgaris and Bambusa balcooa were recorded with their diameter at breast height. Harvest method was employed to estimate the aboveground biomass and from biomass values C stock was determined. C estimate in aboveground vegetation in bamboo farming system ranged from 6.51 (2004) to 8.95 (2007) Mg ha-1 with 87%, 9% and 4% of the total C stored in culm, branch and leaf respectively. The rate of C sequestration was 1.20-1.46 Mg ha-1 yr-1, with a mean of 1.32 Mg ha-1 yr-1. In bamboo farming system under selective felling regime, although the C stock and sequestration was low compared to other agroforestrysystems across the world, it represented a permanent stock. Harvesting of mature culms was balanced by C gain from new culms produced in the clump. Carbon assimilation ratio, an index to evaluate C sequestration potential per unit of C stock, exhibited bamboo farming as an efficient C sequester than other pure plantations or natural forests. Promotion of smallholder bamboo farming systems to reduce atmospheric greenhouse gas levels to receive certified emission reduction is recommended. [ABSTRACT FROM AUTHOR]