Jansons, J., Zālītis, P., Actiņš, A. 2011. The Structure and Thinning Requirements for Broadleaved Stands of Natural Origin in Latvia. Baltic Forestry 17(2): 262-267

The structure of 2 to 9-year-old natural origin broadleaved stands is analyzed, using the method of component analysis. The stands under study represent natural regrowth of trees in fertile cutovers of dry mineral, wet mineral, wet peatland, drained mineral, and drained peatland forest growing conditions. For analyzing the internal structure of young stands the following traits are used: a) the forest stand before felling and the forest adjoining the cutover - 22 traits; b) the structure of ground cover vegetation in cutover - 31 traits; c) the structure of young stand and soil characteristics - 45 traits. The results of component analysis show that the 160 young stands of the age from 2 to 9 years ought to be treated as a single population that could be denoted by a common term – young stands in fertile forest types.
The initial density of natural origin broadleaved stands is notably high: in 89 % of the stands surveyed the number of stems exceeded 10,000 trees/ha while in individual cases it exceeded 120,000 trees/ha. The number tree stems shooting up naturally does not depend from the cutover width. As it follows from the analysis of stand structure (species composition and height), in a cutover the young stand may form a variety of biogroups. Because of significant differences in biogroup structure a unified thinning regime is not suitable for the whole site. In such cases the tending of young broadleaved stands ought to follow the biogroups of particular tree species.

Key words: young broadleaved stands of natural origin; forest stand structure