Height growth, diameter-height relationships and branching architecture of Pinus massoniana and Cunninghamia lanceolata in early regeneration stages in Anhui Province, eastern China: effects of light intensity and regeneration mode

To determine the growth strategies during early regeneration stages of two major coniferous species ( Pinus massoniana and Cunninghamia lanceolata ) in a secondary mixed coniferous forest in the Huangshan region of Anhui Province, eastern China, we examined height growth, diameter-height relationship and the relationship between main stem and lateral branch elongation in saplings, with a particular focus on the effects of light intensity and regeneration mode (seedlings versus sprouts). When light intensity was sufficiently high, the extension growth of main stems was greater and more positively related to initial size for P. massoniana than for C. lanceolata . The slenderness of the stem form increased in the following order: C. lanceolata seedlings < P. massoniana seedlings < C. lanceolata sprouts. P. massoniana became less slender with increasing light intensity. P. massoniana had shorter branches than C. lanceolata given the same main stem elongation. Growth allocation depended more strongly on light intensity for P. massoniana than for C. lanceolata , with more growth allocated to the main stem under dark conditions. These results suggest that P. massoniana is a typical shade avoider; this species gives priority to extension growth of the main stem, especially when it is shaded. In contrast, C. lanceolata is a shade tolerator; this species allocates more biomass to radial growth of its main stems and to extension growth of branches. Based on these results, the ecological characteristics of P. massoniana and C. lanceolata and the roles of seedlings and sprouts are discussed in relation to stand dynamics of the mixed forests of P. massoniana and C. lanceolata in eastern China.