In the mountainous areas of northern Thailand, a tea agroforestry system referred to as the “miang 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±21.68Mg 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.

We evaluate the efficacy of artificial shade shelters in promoting seedling growth and ecophysiological traits in degraded tropical forest land. Seedlings of Dyera costulata were planted in an open control plot and two open-top shade shelters (2 and 3m in height). Leaf traits, including nitrogen content, the ratio of variable to maximum fluorescence (Fv/Fm), and chlorophyll content (SPAD value) were assessed in the nursery prior to planting, and again at 2, 7, 12, and 16 months after planting. Seedling height, diameter, biomass, and leaf number were also assessed. Shade shelters reduced light intensity to approximately 70% and maximum temperature by up to 3.1°C. Minimum daily air humidity was up to 12% higher in the shelters relative to the open control. Seedling growth was better under both shelters relative to the open control, but particularly for the 2m shelter. Seedlings planted in the open lost roughly half their leaves immediately after planting due to environmental stress, whereas leaves were retained by seedlings under the shelters. A decrease in the Fv/Fm ratio was observed in the open control both 2 and 7 months after planting, indicating photoinhibition. The maximum photosynthetic rate decreased in all conditions immediately after planting, but seedlings under the shelters recovered faster, especially in the 2m shelter. Decreases in leaf number and photosynthetic capability in the initial stages following planting may limit seedling growth in open conditions. The improved growth and ecophysiological parameters under the shelters persisted for up to 16 months after planting, indicating that shelters may be valuable tools for reforestation and rehabilitation in degraded tropical forests.