Extended summed dominace ratio, E-SDR, for comparison of grassland vegetation
1995
Yamamoto, Y. (National Grassland Research Inst., Nishinasuno, Tochigi (Japan)) | Kirita, H. | Ohga, N. | Saito, Y.
The summed dominance ratio, SDR, has been used to explain the species dominance in grassland community studies. The SDR2 for a given species is defined as the average of the following two quantities: (1) relative coverage and (2) relative plant height of each species to the respective maximum values in one community. Then, the SDR2 takes a value between 100 and 0. Since this index cannot be used for comparing the vegetation among various communities, a new index, the extended summed dominance ratio, E-SDR2 was developed and described in this paper. In the new index, the range for the selection of the maximum coverage or height in calculating the SDR2 is extended from one community to all the related communities. We selected, as an example, a comparison between the E-SDR2 and the SDR2 calculated using date which had been accumulated in a semi-natural grassland with four different treatments in the Tohoku Area for 11 years. All the values of the SDR2 for Miscanthus sinensis were 100 in every treatment in all the years, which the values of the E-SDR2 for M. sinensis varied with the treatments or years and all were lower than 100. We concluded that the E-SDR was the available index for comparing the vegetation among various communities which were calculated from the plural quantities like the SDR
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