The influence of stand density on Mn and Fe concentrations in beech leaves

A shelterwood system is widely used in forest management practice. Favourable ecological conditions for the growth of desired natural seedlings are provided by a successive canopy reduction. The impact of these changed conditions is reflected to the greatest extent in the morphology and structure of beech leaves. Differences in the leaf structure can mainly be seen between sunlit and shaded leaves and are themselves manifested in changes of element contents in leaves according to the respective conditions. The relationships between analysed variables were studied during research (1996-1997) in stands of different initial stand density (0.3, 0.5, 0.7 and 0.9), resulting from the shelterwood cut of different intensity (1989). The second criterion was the social status of a tree in stands (dominant, codominant and subdominant) and the third one was the position of leaves in the tree crown (upper, middle and lower part of crown). In the framework of this research the concentrations of Mn and Fe including other macronutrients in beech leaves were evaluated. This paper deals only with manganese and iron due to a limited range of pages. The concentrations of Mn a Fe were studied in beech leaves collected from upper, middle and lower parts of beeches with a different social status. In some cases, statistically significant influences of shelterwood cutting intensity on the analysed variables (metal concentration, dry weight, etc.) were proved at a significance level α = 0.05. It applies to manganese quantity accumulated in leaves of dominant, codominant, and subdominant trees, unit trees, Mn concentration in assimilatory organs, dry mass, iron concentration, etc.