Aboveground biomass and carbon sequestration potential of tea and shade trees in Miang tea gardens, an agroforestry system in Northern Thailand

Abstract

In the mountainous areas of northern Thailand, a tea agroforestry system referred to as themiang tea garden has been maintained by smallholders for more than a hundred years. To discuss the ecological advantages of the miang tea garden system, we determined the spatial distribution patterns of these gardens and the relationship between shade trees and tea trees, emphasizing their aboveground biomass. We developed an allometric model for estimating the aboveground biomass of the stool-shaped tea trees. The area utilized for tea tree cultivation was approximately 72 % of the total study area, and the remaining 28 % was classified as forest patches or abandoned gardens. In miang tea gardens, trees other than tea trees were used by farmers to moderate the amount of sunlight reaching the tea leaves. Additionally, these trees ensured an alternative source of income for the farmers. However, we suggest that the canopy openness should be maintained at more than 25 % to prevent tea leaf growth inhibition. The carbon content in the miang tea garden system was 45.51±21.68 Mg C ha−1, considerably higher than that in other types of upland agriculture. The miang tea garden could represent an efficient land-use system supporting sustainable economic activities in areas with geographical limitations for the cultivation of other crops.