杉木二代优良家系不同等级苗造林效果及增产效益

选择杉木第2代种子园8个家系，分不同苗木等级进行造林对比试验。在杉木小径材培育年限16 a内，对1~5年、8年和16年生杉木的生长量进行分析，结果表明：不同等级的苗木，造林后的前4年在树高、胸径和材积生长方面差异达显著水平，但随着年龄增大其差异明显减弱，5年生后差异不显著；年抽高的影响表现在造林的前2年，第3年差异不显著；家系间的差异达极显著水平；家系与等级苗间交互作用不显著；造林成活率有一定的差异；子代和亲代在生长性状上存在着极密切的相关关系。生产中在选择优良家系或品系壮苗的基础上可取得40%以上材积增益。同时家系和个体的早期生长量受到苗木质量的影响较大。因此优良家系或优良个体的选择在苗木5年生以后进行，才能取得更好的选择效果。

Study on forestation and gain productivity for different grade seedlings of the second generation family of Cunninghamia lanceolata

The comparative tests of forestation were made.The different grade seedlings,which were from 8 Chinese fir families of the second generation seed orchard were selected as the samples. Within 16 years,which was the rotation age for small dimension wood cultivation,the growth rate were analyzed when tree was 1-5 years,8 years and 16 years old.The results showed that there were significant differences among height,DBH and stem volume of different grade seedlings before the age were 4-year.And those were not si...