Rotation System FOR Cardamom plantIN G and forest REGENERATION IN THE Tropical Rainforest of southwest China

The cultivation of cardamom (Amomum villosum) in tropical rainforest led to biodiversity decrease and soil degradation. After removal of cardamom in the rainforest of Xishuangbanna of Yunnan, SW China, ecological restoration experiment was carried out from 1998 till 2001. The results showed that the number of plants increased, exceeding that of primary rainforest. The species richness, plant diversity and evenness had increased prominently, similar to the values of primary rainforest. The flora developed along that of tropical rainforest. In the rainy season, seedlings grew faster in areas where cardamom had been removed compared with that of primary rainforests, but there was no difference in the dry season. The biomass of seedlings was 636.1 ± 43.4 g m-2 after two years, exceeding that of the primary rainforest, due to the rapid growth of herbs and ferns. The water content of soil improved and was not different from that of primary rainforest. The organic matter content of deep soil increased remarkably but available phosphorus needed a long time to restore. The available surface calcium was lost through rain water. A new pattern of rotating cardamom planting in tropical forests was recommended.