Effects of Rotation Length and Repeated Harvesting on the Sprouting Reproduction of Acacia auriculiformis

Two studies were established to investigate the effects of rotation length and repeated harvesting on the sprouting reproduction of Acacia auriculiformis in Shangyong Village Forest Farm (19°14'N, 110°28'E)of Qionghai City of Hainan Province.The first study was conducted in a split plot design with three replications involving three rotation lengths of 4,5 and 6 years as the main plot and three stand densities(6 667, 5 000 and 4 444 trees planted per hectare)as the sub-plot.Results showed that both the rotation length and stand density had no significant effects on the percentage of stump sprouting and the number of sprouts produced per stump. The DBH and length of sprouts decreased significantly with the increase of rotation length.The differences in DBH and length of sprouts between the stands with different densities were not significant.The total biomass and volume production from the first harvest together with the standing sprouting forests decreased with the increase of rotation length.To maximize the sprouting reproduction of A. auriculformis,a rotation length of 4 years is recommended. In the second study,eight combinations of rotation lengths of 2+3+4,3+2+4, 3+3+3, 2+4+3, 4+2+3, 2+7, 3+6,4+5 years were involved into a repeated harvesting trial for A. auriculiformis.Results showed that it is possible to establish the second sprouting forest of this species by sprouting,and coppicing can return it to juvenility.There was no significant differences in the percentages of stump sprouting and surviving rate between the first and the second harvest. The total volume and biomass production between the tested eight combinations of rotation lengths were not significantly different.For minimizing the production cost and increasing the economic profits,a combination of rotation length of 4+5 years is recommended for a management period of nine years.