银杏萌芽更新林生长和生产力分析

Investigation on the Growth and Productivity of Sprout Regeneration Ginkgo Stands

以56年生的丛生银杏为研究对象,对丛生银杏复干的数量、胸径及材积量进行每木调查和解析木分析,探索银杏用材林萌芽更新的可行性。结果表明,上层林冠的复干均为第一代复干,且主干明显,干形规整饱满,净树干较高;第二代、第三代、第四代等的复干生长不良。上层林冠的复干数1.98根,其中复干数为1和2根的丛数所占比例最大;复干平均胸径30.9 cm,多分布在20-40 cm区间内,其中最粗复干的平均胸径35.2 cm;复干平均材积量1.043 m3。上层林冠复干数与单丛材积量具有良好的抛物线关系。结论：（1）仅考虑上层林冠复干数,在自然萌育条件下,每个伐桩自然定株2根第一代复干;自然定株4-5根复干时材积量最大。（2）在施肥、抚育、修剪等集约化经营条件下,建议保留2-3根复干,亦可获得较高的材积量。

The quantity,DBH,volume of multi-trunks of 56-year ginkgo strand from natural sprout regeneration were measured by means of examining each wood and analyzing the parse tree to explore the feasibility of ginkgo timber afforestation by sprout regeneration. The main results showed that the multi-trunks occupying upper canopy were the first generation of ones that had straight trunk and high clear bole height,but the second,third,fourth etc.generations of multi-trunks failed to grow well.The average quantity of multi-trunks occupying the upper canopy was 1. 98 trunks,the ginkgo clusters of one and two multi-trunks occupying the upper canopy were the most.The average diameter of the multi-trunks occupying the upper canopy was 30.9 cm,and mostly between 20 cm and 40 cm.The average diameter of the most thick multi-trunk per cluster was 35.2 cm.The average volume of the multi-trunks occupying the upper canopy was 1.043 m3.The multi-trunks occupying the upper canopy were the first generation of the multi-trunk with straight trunk and large height,but the second,third,fourth generations of the multi-trunks fail to grow well.The multi-trunks occupying overstory and the volume per cluster has good parabola relationship. In conclusion,only considering the multi-trunk quantity occupying the upper canopy,each ginkgo cluster was the first generation of two multi-trunks in the natural regeneration and breeding conditions.Considering the multi-trunk quantity and volume occupying the upper canopy,each ginkgo cluster with four or five multi-trunks obtained higher volume in the the natural generation and breeding conditions and two or three multi-trunks per ginkgo cluster was recommended under intensive operation conditions based on fertilization,thinning and pruning,etc.