干旱区生态环境知识资源中心

Karst rocky desertification occurred in the southwest part of China was a seriously environmental problem, it is very important that expressing, dating, and reconstructing karst soil erosion process and history for understanding geomorphology of karst rocky desertification. Whereas accurately understanding karst soil erosion met a great obstacle of measuring problem for karst soil erosion from underground due to the dualistic systems of overground and underground. This was first time using exposed root anatomical features to imply karst soil erosion in China. Exposed and unexposed root samples in Puding, Guizhou, China were collected, and anatomical features were compared, parameters were measured, so as to obtain indicated information of soil erosion. Annual ring width could be appropriately applied to study the relationship of tree growth with environmental factors for the average sensitivity was larger than 0.2 for annual ring responding to soil layer. Tree root anatomical features were compared between exposed and unexposed root. The annual ring of unexposed root was smoothly increased from pith and decreased slowly when closed to bark, vessel size was the same and evenly distributed in each ring. Annual ring, pattern of vessel, and vessel size of exposed root was the same as unexposed root in prophase but an obviously mutation followed, annual ring narrowed, vessel lumen area reduced, vessel number decreased. After this mutation, a regular trend was shown but annual ring was narrower than unexposed root. From the anatomical changes of exposed root, the exact time of root exposure can be identified and the beginning of soil erosion happening. The response of anatomical features of tree root to soil erosion can offered a new method for the study of karst soil erosion and soil erosion historical record. (C) 2010 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Society for Resources, Environment and Engineering