An Analysis of the Growth and Structure of Mixed Plantations Consisted of Pinus massoninia and Broadleaf Species

ANOVA was used to analyze the 6 year's and 11 years' growth data of the Pinus massoniana (pine) plantation mixed with Castanopsis hystrix, Michelia macclurei, Mytilaria laosensis or Cuninghamia lancelata respectively. The result showed that:(1)The differences of tree height (H) and diameter at breast height (DBH) of mixed pine plantation were not significant among treatments at the age of 6, and the mean H and DBH were respectively 4.6—4.9 m and 6.0—7.4 cm, of which the growth was very poor in mixed stand with Mytilaria laosensis and the differences of DBH and accumulated stock of mixed pine plantation were significant at 11-year-old stands, among which the pure pine stand (the controlled treatment) with 12.6 cm in DBH and 121.05 m3·hm-2 in accumulated stock is the best for tree growth, however, the pine stand mixed with Mytilaria laosensis is the worst with 8.7 cm in DBH and 43.18 m3·hm-2 in accumulated stock.(2)At the age of 11, the mean H for 4 different species in relevant mixed stands respectively were 14.3 m for Mytilaria laosensis, 10.2 m for Castanopsis hystrix, 9.9 m for Michelia macclurei, 9.1 m for Cuninghamia lancelata and 8.1 m for Pine. The pine trees in stand mixed with. Mytilaria laosensis and the Castanopsis hystrix trees in pine-Castanopsis hystrix mixed stand mixed should be thinned to a suitable density. (3)Two mixed stands with composition of P.massoniana×Castanopsis hystrix, and P.massoniana×Michelia macclurei are suitable to grow valuable big diameter timber for broadleaf species, and Mytilaria laosensis is recommended to plant as pure plantation with the best initiative density of 1 000—1 600 trees hm-2.