Spatial patterns of trees from different development stages in mixed temperate forest in the Hyrcanian region of Iran

Mixed beech (Fagus orientalis Lipsky) forests are very important to the Hyrcanian region of Iran because of their high degree of naturalness and as a source of wood production. Determination of tree spatial patterns over development stages is a first step in understanding underlying processes driving regeneration and forest dynamics. Spatial patterns of trees from three development stages (initial, optimal and decay) of an untouched mixed beech forest were quantified within three 1-ha plots. To prepare the stem maps, we measured each tree with a DBH larger than 7.5 cm using the azimuth-distance method. Spatial patterns were then analysed using Ripley's K-function. Results indicated that the number of trees decreased from the initial stage to the decay stage, with tree spatial patterns being aggregated, slightly aggregated and highly randomized for initial, optimal and decay stages, respectively. Differences in spatial patterns among the development stages are not unexpected considering that such unmanaged forests are driven by gap dynamics which results in interactions between gap filling individuals.