不同轮伐期和重复采收对大叶相思萌芽更新和林分产量的影响*

不同轮伐期和不同林分密度以及不同轮伐期组合和重复采收对大叶相思萌芽更新和林分产量影响的研究结果表明：①轮伐期对伐桩的萌芽力没有显著影响，但对萌芽林的生长有显著或极显著影响；林分密度对伐桩萌芽力和萌芽林生长均无显著影响。林分的材积和生物量总产量（种植后８ａ）随轮伐期的延长而减少。研究证明，大叶相思实生林萌芽更新的首采轮伐期以４ａ为最佳。②矮林作业能在一定程度上使大叶相思幼态化。在种植后５～６ａ内对这一树种进行第二次采伐的更新效果与第一次采伐的更新效果之间没有显著差异。对于以９ａ为一个经营期来说，以萌芽更新方式经营２代与３代其更新效果和林分总产量相当。为减少营林成本提高经济效益，建议经营两代即可，轮伐期组合以４＋５为最佳。

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.