Species diversities analyzed by density and cover in an early volcanic succession
✍ Scribed by Tsuyuzaki, Shiro
- Publisher
- Springer-Verlag
- Year
- 1996
- Tongue
- English
- Weight
- 467 KB
- Volume
- 122
- Category
- Article
- ISSN
- 1573-5052
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✦ Synopsis
To evaluate alpha diversities, various variables such as density, cover, volume, and weight have been used. However, density is often a distinct variable from the remaining three. To clarify differences in diversity measured by those two kinds of variables, the data collected in fourteen 2 x 5 m permanently-marked plots on Mount Usu, Japan, which erupted during 1977 and 1978 in growing seasons from 1983 to 1989 was analyzed, using Shannon's species diversity (H') that is represented as a result of combination of species richness and evenness (J'). H' and J' were evaluated by density (density H' and jr) and cover (cover H t and jr). Cover H r and J' were significantly lower than density H ~ and f , indicating that cover H ~ has different characteristics from density H/. Those differences are due to differences in evenness, because species richness is the same. The rank orders of species density are different from those of cover. The predominance of a few perennial herbs greatly decreases cover evenness, while seedling establishment success influences density evenness. Therefore, I propose that, during the early stages of succession on harsh environments such as volcanoes, density diversity represents seedling establishment success rate while cover diversity expresses vegetative reproduction success rate.