The Errors in Visual Estimation of Plants Cover in the Context of Education of Phytosociology

In vegetation science including phytosociology, visual estimates of plant cover and point method belong to the common field method to record species composition and their abundance. Two methods were compared: Braun-Blanquet scale and point method using Levy bridge. A group of students performed measurements in five plots belonged to an oak-hornbeam forest Tilio-Carpinetum. It was revealed that there is a very high discrepancy in a observed number of species. Total mean numbers obtained are 13.4 and 31.2 for point method and Braun-Blanquet method respectively. However, there is the significant positive and medium correlation between two methods in terms of estimation of abundance of species. It can be concluded that point-method is not suitable for study of forest floor vegetation. It can be merged with other methods. Due to many repetitive measures, it can be helpful in learning of recognition of species.