孟加拉羯布罗香(Dipterocarpus turbinatus Gaertn. F)外生侵染菌根的水平分布

本文论述了孟加拉国吉大港大学校园里,不同年龄(5、10、20年)的羯布罗香(Dipterocarpus turbinatus Gaertn. F)人工林内,距树木基部不同距离(1、2、3、4米)处,外生侵染菌根的水平分布状况.在山的3个部位(顶部、中部和下部)对各人工林外生侵染菌根的侵染进行了测定.在不同水平分布距离处的树下采集了1000cm3的根际土壤样本,不同距离和山高处的外生侵染菌根浸染率差异显著.在5年和10年林龄的人工林内,浸染率随着距树的距离的增加而快速下降,而在20年林龄的人工林内,浸染率随着距树基部距离的增加而急剧增加.山下部20年生人工林内距树4m处的浸染率最高(81.3%),山顶部5年生人工林内距树4m处的浸染率最低(55.33%).图6参32.

Horizontal distribution of ectomycorrhizal infection in Dipterocarpus turbinatus plantations of Bangladesh

Garjan (Dipterocarpus turbinatus Gaertn. F) is a highly ectomycorrhizal tree species growing in hilly areas of Bangladesh. The horizontal distributions of ectomycorrhizas (ECM) in different distances (1, 2, 3 & 4m) from the tree base were determined in 5, 10 and 20-year-old D. turbinatus plantations of Chittagong University Campus (CUC) in 2003. The ECM infection (%) in roots was counted at three hill positions (top, mid and bottom) for each of the plantations. Samples of 1000 cm³ rhizosphere soil were collected from underneath the trees at different horizontal distances. The percentage of infection at different distances and hill elevations varied considerably. In 5 and 10-year-old plantations, the occurrence of infection (%) was rapidly declined with increasing distances, while in 20-year-old plantation, the infection increased sharply with increasing distances from the tree base. The highest infection (81.33%) was found at 4 m distance from the tree at bottom hill in 20-year-old plantation and the lowest (55.33%) at the same distance at the top of the hill in 5-year-old plantation.