Abstract:

Five trees from each of three level of diseased Masson Pine (Pinus massoniana Lamb.)stand affected by air pollution and acid rain were collected from LiuZhou of Guangxi Autonomy, China. The results of wood structural characteristics of the seriously diseased (S_II) trees as compared to the slightly diseased (S_I) and no diseased (S₀) trees obtained from the study were as follows:1. The width of sapwood: S_II (7.62cm) < S_I(8.57cm) < S₀(9.30cm);2. The width of annual ring: S_II(3.48cm) < S₀(4.82mm) < S_I(5.00mm);3. The percentage of latewood: S_II (37.6%)>S_I (36.7%)>S₀(36.2%);4. The percentage of traicheid wall: S_II(48.13%)>S_I(47.51%)>S₀(46.08%);5. The ratio of tissueThe tracheid: S_II(91.9%) < S_I(92.69%) < S₀(92.80%);The ray: S_II(7.34%)>S₀(6.78%)>S_I(6.55%);The resin canal: S_II (0.68%) >S_I (0.57%) >S₀ (0.52%);6. The Morphology of tracheidThe length of tracheid: S_II(3828μm) < S_I(3966μm) < S₀(4372μm);The tangential diameter of tracheid: S_II(36.11μm) < S₀(37.28μm) < S_I(37.72μm);The tangential diameter of tracheid Iumen: S_II(24.91μm) < S₀(24.95μm) < S_I(26.12μm);The tangential wall thickness: S_II(5.06μm) < S_I(5.25μm) < S₀(5.7μm);The radial diameter of tracheid: S_II(35.08μm) < S_I(37.51μm) < S₀(38.10μm);The radial diameter of tracheid lumen: S_II(24.97μm) < S₀ (26.69μm) < S_I(27.07μm);The radial wall thickness of tracheid: S_II(5.6μm) < S_I(5.8μm) < S₀(6.17μm);7. The fibrillar angle: S_II: S₀ (7.0°) < S_I(7.3°);Diferent analysis indicated that the differences among the width of sapwood, the width of annual ring and the radial diameter of tracheid of seriously diseased trees and that of slightly diseased trees and no diseased trees were significant, but the others were insignificant.

Key words: Acid rain, Air pollution, Pinus massoniana, Wood structure