Researches on Population Ecology

, Volume 18, Issue 2, pp 243–260 | Cite as

Analysis of spatial association between two species based on the interspecies mean crowding

  • Syun'iti Iwao

Summary and Conclusion

The measurement of spatial association between two species is considered on the basis of interspecies mean crowding. Two indices of overlapping, γ andC p, are derived as geometric and weighted arithmetic means of the same component ratios related to inter-and intraspecies mean crowdings. Both indices behave in a similar way, ranging from 1 when the distributions of two species are completely overlapped to 0 when they are completely exclusive with each other. The former is essentially identical with indices proposed byKuno (1968) andPianka (1973), and the latter is a modified form ofMorisita's (1959)C σ index. Indices to measure the degree of spatial correlation between species, Ω andR μ, are then derived for both kinds of overlapping indices, which vary from 1 in complete overlapping, through 0 in independent occurrence, to −1 in complete exclusion.

Various kinds of interspecies association are analyzed using these indices and an extended form of the\(\mathop m\limits^* - m\) regression graph which provides a convenient way of indicating the spatial interrelation between two species as well as distribution patterns of respective species.

The method presented in this paper may also be applicable to compare temporal distribution patterns between species, similarity between communities, etc. For such a wider application which includes continuous as well as discrete distributions, the interpretation of intra-and interspecies mean crowdings is not necessarily appropriate, and hence the concept of mean concentration with the symbols\(\mathop c\limits^* _X (\mathop {m_X + 1}\limits^* )\) and\(\mathop c\limits^* _Y (\mathop {m_Y + 1}\limits^* )\) for intraspecies relation and\(\mathop c\limits^* _{YX} (\mathop {m_{YX} }\limits^* )\) and\(\mathop c\limits^* _{YX} (\mathop {m_{YX} }\limits^* )\) for interspecies relation is suggested.


Spatial Association Stem Borer Quadrat Size Independent Distribution Random Line 
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Copyright information

© The Society of Population Ecology 1977

Authors and Affiliations

  • Syun'iti Iwao
    • 1
  1. 1.Laboratory of Applied Entomology and Nematology, Faculty of AgricultureNagoya UniversityNagoyaJapan

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