Botanische evaluatie van enkele natuurreservaten in Overijssel

A botanical evaluation of some nature reserves in the province of Overijssel The method of botanical evaluation by MENNEMA (1973), based on the flora statistics of VAN DER MAAREL (1971) depends upon inventarisation of 1 kilometer squares. In the present study the floristic lists of seven nature reserves in the province of Overijssel were used and the results compared with those of Mennema. Furthermore this new objective method was used to attempt to compare the relative botanical importance of the reserves. The results fairly well agreed with those of Mennema using results from reserves of c. 40 ha, but this was not the case with the smallest reserve ,De Maat’ of 8 ha. The author considers that the selected reserves have natural boundaries and the values of these boundaries become obscured using the Mennema method. Providing the area studied was not too small, the results obtained from data collected within the boundaries of the nature reserves were comparable with those obtained by the Mennema method using kilometer squares. If the size factor is borne in mind the author suggests that different areas of nature reserves may be compared, and the results used in the same way as those obtained by the Mennema method.