The Effect of Different Slope Aspects and Soil Properties on the Growth of Various Strains of Balsa Trees

The manufacture of large wind turbine blades generally uses composite sandwich panels with balsa wood as the base materials. The balsa wood in China is completely dependent on imports, often facing supply instability and periodic shortages. To ensure the security and stability of the balsa wood supply chain, wind power companies have initiated extensive promotion efforts in the Xishuangbanna of Yunnan Xishuangbanna's complex topography and unique environmental conditions present distinct challenges. Clarifying the site suitability for balsa cultivation and understanding the growth characteristics of different balsa varieties are urgent issues that need to be addressed for the domestic production of balsa trees. The results showed that in the Xishuangbanna, shaded slopes are more suitable for the cultivation of balsa trees. The results showed that in the Xishuangbanna region, shaded slopes are more suitable for balsa trees cultivation, with the stem wood volume of Indonesian balsa germplasm and Ecuadorian balsa germplasm on shaded slopes reaching 2.76 and 1.93 times, respectively, that of the corresponding germplasm on sunny slopes. In the early stages, soil moisture conditions on shady slopes are more conducive to the rapid development of forest stands. Soil total phosphorus, nitrate nitrogen, exchangeable calcium, and various available trace elements (manganese, copper, zinc) promote growth, whereas excessively high levels of exchangeable aluminum and available iron exert inhibitory effects. A comparison between the two provenances indicates that the Ecuadorian balsa exhibits superior branch-free height, whereas its diameter at breast height (DBH) growth rate is slower than that of the Indonesian provenance. Therefore, it is recommended to cultivate balsa trees on shaded slopes using Ecuadorian and Indonesian varieties. To achieve higher yields, soil improvement measures should be implemented, including the application of calcium fertilizer, pH adjustment to mitigate aluminum toxicity, and supplementation of trace elements such as zinc, copper, and manganese.