川中丘陵区低效防护林分“开窗补阔”改造试验研究

为了改善现有低效防护林分，于2006年选择四川绵阳官司河流域的柏木纯林、松柏混交林和马尾松纯林3种典型低效林分，各设置3个25 m×40 m的样地，再将每个样地划分为6个10 m×10 m小样地，对其中5个小样地采伐相同株数的原有乔木，并在采伐窗内分别补植香樟、台湾桤木、栓皮栎、窄冠刺槐、葛藤，1个样地作为对照，开展“开窗补阔”改造试验研究。结果表明:1)柏木纯林、松柏混交林、马尾松纯林林下灌木和草本的平均盖度分别比对照高40.88%～55.13%、42.62%～52.53%、45.33%～54.73%和22.89%～54.56%、7.16%～33.78%、21.15%～57.82%。不同改造模式的物种丰富度和Shannon-Wiener指数均明显高于对照。其中，灌木物种丰富度比对照高26.67%～75.00%，Shannon-Wiener指数比对照高17.89%～38.06%；草本物种丰富度比对照高30.00%～100.00%，Shannon-Wiener指数比对照高12.52%～34.65%。2)土壤物理性质得到改善。柏木纯林、松柏混交林、马尾松纯林不同改造模式土壤容重分别比对照低14.31%～16.47%、10.92%～13.77%、7.00%～9.41%；土壤总孔隙度分别比对照高12.27%～16.93%、11.43%～15.53%、13.46%～18.09%。3)从不同森林类型不同补植树种效果来看，香樟、台湾桤木、栓皮栎和窄冠刺槐均可用于在柏木林中补植，但立地条件差的林分中以补植栓皮栎为宜。马尾松纯林中应补植香樟和栓皮栎，但补植香樟时应选择土层较厚，土壤含水量较高的林分，所有补植的苗木应以2年生大苗为宜。

Coupe Transformation of Low-efficiency Protection Forest in the Central Hilly Sichuan

In order to improve the forest eco-functions, a study on coupe transformation (cutting and replanting in small patch) was carried out in pure masson pine forest, pure cypress forest, and fixed pine and cypress forest. In each forest type, one 25 m × 40 m sample plot was established and each plot was divided into 6 10 m ×10 m sub-plots; equal number of trees was cut from five sub-plots (another one without cutting serves as control). After cutting, camphor, alder, oak, locust tree and pueraria were replanted in the opening of the five sub-plots respectively. The results showed that: 1) after coupe transformation, the shrub and herb coverage in pure cypress, pure pine, and mixed cypress and pine forests were respectively 40.88% to 55.13%, 42.62% to 52.53%, 45.33% to 54.73% and 22.89% to 54.56% 7.16% to 33.78%, 21.15% to 57.8% higher than that of the control. The species richness and Shannon-Wiener index in different transformation models were significantly higher than that of the control. Of which, species richness and Shannon-Wiener index of shrub are 26.67% to 75.00%, 17.89% to 38.06% higher than that of the control; they are 30.00% to 100.00% and 12.52% to 34.65% higher than that of the control for herb. 2) Soil physical features were improved. Soil bulk density in pure cypress, mixed cypress and pine, and pure pine forests were 14.31% to 16.47%, 10.92% to 13.77%, 7.00% to 9.41% respectively lower than that of the control; total soil porosity were 12.27% to 16.93%, 11.43% to 15.53%, 13.46% and 18.09% higher than that of the control. 3) In terms of the survival rate of replanted seedlings, camphor, alder, oak and locust tree could be used in pure cypress forest; but in poor site conditions, oak was more appropriate. Camphor and oak could be used in pure pine forest; but camphor preferred the site with thicker soil depth and higher soil water content. Furthermore, it was proven that 2 years old seedlings for the replanting were much better to ensure the reasonable survival rate and sound growth.