Acta Botanica 39. (1995)
1995 / 1-2. szám - TÓTHMÉRÉSZ BÉLA: Density dependent and density independent representation of indirect spatial series analysis
Acta Botanica Hungarica 39 (1—2), pp. 43—50 (1995) DENSITY DEPENDENT AND DENSITY INDEPENDENT REPRESENTATION OF INDIRECT SPATIAL SERIES ANALYSIS B. TÓTHMÉRÉSZ Ecological Institute of Kossuth L. University, H-4010 Debrecen, P.Q. Box 14, Hungary (Received: February 7, 1994) A density independent representation of indirect spatial series analysis is proposed and it is compared to the density dependent representation. In this case the indirect spatial statistics are plotted against the average number of individuals instead of the plot size. Differences of density dependent and independent representations are displayed by the analysis of three (semi-artificial) communities which have different densities but the same pattern. Density dependent and independent representations suggest strikingly different interpretations which should be bear in mind during the analysis of spatial pattern. I also mention some further possibilities to create density-free representations. Introduction Spatial statistics are usually plotted against the (logarithm) of plot size in botanical applications (JUHÁSZ-NAGY and PODANI 1983). Direct spatial statistics are straightforwardly derived from the vegetation of sampling plots. The case of indirect spatial statistics is more sophisticated. The number of plots having different species list is counted for a given plot size and the statistics characterizing the vegetation are calculated from this derived data set. These methods were developed by 3UHÄSZ-NAGY (1976) and he used these statistics with a special sampling arrangement which use a series of increasing plot sizes. It is mentioned as spatial series analysis (PGDANI 1992; TÓTHMÉRÉSZ 1994). Indirect spatial statistics in a spatial series analysis always have a global maximum; sometimes also have more than one local maxima (BARTHA 1990; PODANI 1984; TÓTHMÉRÉSZ and ERDEI 1992). The maxima of these statistics indicate particularly important plot sizes, usually mentioned as characteristic areas (JUHÁSZ-NAGY 1967). Using the characteristic areas of different indirect spatial statistics a characteristic ordering and characteristic interval can be defined which have crucial role in describing the vegetation's coenological states (JUHÁSZ-NAGY 1967; BARTHA 1990). 0236-6495/95/2 4.00 © 1995 Akadémiai Kiadó, Budapest