Structure of different stand layers and management optimization strategies in a Masson pine plantation in southern subtropical, China

Abstract Forest vertical structure has significant influences on a series of structural and functional properties of forest ecosystems, and is often manipulated by silvicultural practices. However, how forest structure changes with stand height has not been well understood although their occurrence is highly correlated with forest management. An across-stand analysis of forest structure was conducted to characterize the structure of different stand heights in a Masson Pine plantation in southern subtropical China. Totally 238 plots were measured. We categorized all tree individuals into four layers according to tree height: the regeneration, lower, middle and upper layers. Species composition, species richness, abundance, diversity, DBH , volume, and slenderness were quantified and compared among four different stand layers. The results showed that (1) species richness and abundance index increased firstly and then decreased with increasing stand layer. (2) Tree individuals with diameter >20 cm dominated at the upper stand layer (tree height >15.6 m). (3) Although tree individuals at the lower layer contributed substantially to forest area at both plot and stand levels, their volume was less influential than larger trees because about 12.6% of the total tree individuals at the upper layer provided 46.5% of total volume. (4) Trees with stem slenderness values smaller than 100 and DBH >20 cm were predominantly located at the upper layer. The findings suggest that the features of vertical structure were useful for designing silvicultural systems of Masson pine plantation. Future research is needed to gain a better management strategy linked with structure characteristics.