干旱区生态环境知识资源中心

The characteristics of the multiple bands of Haloxylon ammodendron (C.A. Mey) Bunge tree-ring were studied in three edaphic types. Age equations were derived relating ground diameter and tree height, and the effects of irrigation on numbers and widths of growth bands at the longest radius were analyzed. Results showed that the number of growth bands ranged from 3.3 to 6.3 per year, the widths ranged between 0.181 mm and 0.473 mm. Multiple growth bands formed every growing season, leading to the conclusion that multiple growth bands in H. ammodendron tree-ring are a natural feature. A dark brown layer and a light brown one make up one growth band. The dark brown layers consists of fibres and vessels as well as some ray parenchyma, and each fibres layers with 22-35 cell layers; the light brown layers formed by vessels, fibres and abundant paratracheal axial parenchyma are 4-15 cell layers. The widths of growth bands at the longest radius increased significantly as the irrigation amount increased in three edaphic types (p<0.01). The numbers of growth bands at the longest radius had significant positive correlation with irrigation times. The ratio of dark brown layers to light brown layers of growth bands at the longest radius appeared to have a rising tendency with the increase in irrigation amount and times.