The response of four windbreak trees to fertilization during planting in Penghu.
Use of fertilizers for enhancement of growth, nutrient status and survival rates of windbreak trees was investigated in the Penghu area of Taiwan. Seven treatments of compound and organic fertilizers in different rates and combinations were applied during planting, to seedlings of four windbreak species: Casuarina equisetifolia, Hibiscus tiliaceus, Pongamia pinnata and Pouteria oborata [P. obovata]. Diameter at breast height, and height of seedlings was measured for three years. Significant growth responses were observed in the initial stage, except for Pongamia pinnata. Duration of growth response was short and may have been affected by adverse environmental stresses, such as drought, strong northeastern monsoon winds, or salt spray. Nutrient (NPK) concentrations in leaves increased with increasing rates of fertilizer application except for phosphorus concentration in leaves of Pouteria obovata. Fertilizer treatment significantly increased survival rates of Casuarina equisetifolia; similar but not significant trends were found in Hibiscus tiliaceus and Pouteria obovata. The heaviest fertilizer treatment may have caused toxicity, inhibiting some seedling growth. It is concluded that proper fertilizer treatment would benefit windbreak performance in stressful environments.