封山育林对不同发育阶段杉木林植物多样性的影响

Influences of Conservation for Regeneration on Plant Diversity of Ecological Cunninghamia lanceolata Forest at Different Development Stage in Zhejiang

将浙江省杉木公益林划分为3 个发育阶段：≤10 a 为幼龄林;11 - 20 a 为中龄林;〉 20 a 为成熟林.对杉木（Cunninghamia lanceolata）优势林和含杉木混交林的三个发育阶段的乔木层、下木层和草本层的植物多样性进行比较研究.结果表明：杉木优势林的乔木层植物多样性指数都随时间缓慢上升（〈 15%）,成熟林乔木层的异质性和均匀性高于草本层,幼龄林下木层多样性不高,物种数和异质性也都随时间缓慢上升（〈 5%）,下木层均匀性在中龄以后稳定,杉木优势林随着林龄的增加,郁闭度相应增加使得草本层的Gleason 指数从2.62 下降到1.68;含杉木混交林封山育林后幼龄林下木层植物多样性最高,中龄林的物种数、异质性最低,均匀度随时间逐渐降低,各层植物多样性指数在各个发育阶段都表现为下木层 〉 乔木层 〉 草本层,仅有草本层Gleason 指数中幼龄林阶段较高例外;在各个发育阶段杉木优势林的乔木层和下木层的植物多样性都不如含杉木混交林,优势林草本层的物种丰富度、异质性和均匀性指数幼龄林阶段都高于含杉木混交林,中龄林阶段接近,在成熟林阶段都比含杉木混交林低;总体而言,杉木优势林的植物多样性不如相同发育阶段的含杉木混交林.

Ecological Cunninghamia lanceolata forest was divided into three development stages(≤10-year as young, 11-20-year as half-mature and > 20-year as mature) and two forest types(pure C. lanceolata forest and mixed forest with C. lanceolata) in Zhejiang province. 67 sample plots in 23 counties were established for monitoring plant diversities at tree, shrub and herb layer in different forest types. The results showed that at tree layer of pure C. lanceolata forest, plant diversity index increased slowly(<15%), and heterogeneity and homogeneity was higher than that at herb layer in mature forest, while at shrub layer, plant diversity index of pure C. lanceolata forest was not high at young stage, species numbers and heterogeneity increased slowly(<5%). Gleason index at herb layer decreased from 2.62 to 1.68 because of the increase of closure. Mixed young forest had the highest plant diversity index at shrub layer, half-mature one had the lowest species numbers and heterogeneity. Plant diversity index at different layer in different development stages was ordered by shrub layer>tree layer> herb layer, Gleason index of herb layer was an exception. Plant diversity at tree and shrub layer of pure C. lanceolata forest with different development stage was lower than mixed forest. Species richness, heterogeneity and evenness index of herb layer in pure young C. lanceolata forest was higher than that in mixed forest, and got close in half-mature one, but lower in mature than that in mixed forest. The study found that plant diversity of pure C. lanceolata forest was lower than that of mixed forest in the same developmental stage.