Assessment of biomass recovery and soil carbon storage of fallow forests after swidden cultivation in the Bago Mountains, Myanmar

Abstract

The role of swidden fallows in carbon storage is poorly understood, especially in Myanmar, due to the complex and dynamic characteristics of fallows and limited available data. We studied fallow forests formed as a consequence of Karen swiddeners in the Bago Mountains, Myanmar, assessing above- and belowground biomass recovery and soil carbon storage in fallow forests using a chronosequence approach. The accumulated total biomass was 12.13–356.95 Mg ha−1, the accumulated carbon stock was 5.70–167.77 Mg C ha−1, and the soil carbon stock was 5.70–167.77 Mg C ha−1 in the fallow forests. Our analysis suggested that the fallow forests in this study should recover to the total biomass accumulation of old forests after 20–35 years. We established a curve of total biomass accumulation in the fallows against age that can be easily used when the age of the fallows is known. Based on soil carbon analysis, total carbon storage fluctuated with fallow age and decreased with soil depth. The overall soil carbon accumulation in fallow forest soil was 43.63–70.11 Mg ha−1. This study contributes to the understanding of fallow forest and swidden agricultural system carbon stocks and can be used for planning future agreements, such as Reducing Emissions from deforestation and forest degradation in developing countries (REDD+), at national and regional levels.