Abstract
In the Bago Mountains of Myanmar, teak (Tectona grandis Linn.) reforestation using the taungya system has been in continuous operation for more than a century. Under this system, farmers who plant teak trees can cultivate intercrops between the rows of teak. In this region, secondary forests, especially bamboo-dominated forests, are usually slashed and burned to start a new taungya reforestation. To investigate the effect of the burning of bamboo-dominated forests on nutrient dynamics, changes in the soil nutrient status during the slash-and-burn and subsequent intercropping periods of taungya reforestation were examined quantitatively with particular focus on the effect of ash incorporation. After burning, approximately 85.1% of the aboveground biomass was lost and 4.2 t/ha of ash was produced. Although the loss of aboveground biomass was enormous, a significant increase in the amount of exchangeable K in the surface soil was observed. The nutrient dynamics in the soil were heavily influenced by the properties of the K-rich ash, which reflected the chemical composition of the original vegetation. The available P in the surface soil also increased due to a combination of the soil-heating effect and ash incorporation. The burning of bamboo-dominated forests confers certain advantages, including an increase in the amount of readily available essential nutrients such as K and P because bamboo ash contains a large amount of water-soluble K, and sufficient burning enhances the mineralization of organic P by the soil-heating effect.
