An assessment of the O-ring methodology using virgin stands of mixed European beech – Sessile oak

Abstract

Studies aiming at assessment of factors influencing the interdependence among species often rely on assumptions that can significantly change the results. The goal of this study is to evaluate the impact of analytical assumptions on spatial arrangements of trees within mixed species stands. We used the O-ring statistics computed for two species with different shade tolerances (i.e., Fagus sylvatica L. and Quercus petraea L.). The O-ring parameters (i.e., inside radius and width) were evaluated within a replicated design. It was found that inference depends on both radius and width of the ring. We found a sinusoidal dependence between species, with repulsion prevalent at distances less than 1.5 heights of the dominant trees. Same species seems to aggregate at distances ½ height of the dominant trees, and repulse at small and large distances (approximately 8m and ⩾30m, respectively). Different species could assist one – another in establishing the spatial arrangement of the stand, but do not help each-other when size is of importance, as competition for common resources is stronger than for the non-common ones. Using reductio ad absurdum we found that width of the ring could change the interpretation. For the mixture European beech – sessile oak narrow rings should be used for research focused on location while wider rings are suited to size related analyses. Employment of inadequate values for analytical tools, such as ring width, can fail to reveal spatial relationships. The existence of parameter values that capture better particular processes indicates that different hypotheses should be investigated considering some intrinsic properties of the analysed processes.