刺槐萌生林与实生林的生长比较

刺槐是我国重要用材树种和生态公益林树种。针对刺槐萌生林生长状况出现下降等问题,在山东省沂山林场(E 118°36’,N 36°10’)和泰山药乡林场(E 117°19,N 36°17’),选取具有代表性的刺槐实生一代林和萌生二代林林分为研究对象,对林分结构特征、立木生长进程、干形等因子进行调查分析。结果表明:1)刺槐萌生二代林树高在前22年、材积总生长量和材积平均生长量在前17年、材积连年生长量在前14年均大于实生一代林,但随后各个指标生长量均小于实生一代林。2)刺槐实生一代林树干通直,而刺槐萌生二代林绝大部分树干弯曲,难以成材。3)提出用树干弯曲指数描述干形弯曲程度,并根据干形弯曲指数大小,将刺槐萌生二代林立木干形弯曲程度划分为无弯曲、极小弯曲、轻度弯曲、中度弯曲、重度弯曲5级。发现,刺槐萌生二代林中,树干中度和重度弯曲林木约占整个刺槐林的34.8%;树干无弯曲的树木极少,只占0.86%;树干极小弯曲的树木占33.8%。通过分析讨论刺槐连续无性更新林分生长迟缓、干形不良、不能成材成林的原因,认为刺槐无性更新问题是一个值得引起关注和研究的重要问题。

Comparative study of coppice and seeding forest of Robinia pseudoacacia L.

Robinia pseudoacacia L. is an important timber and non-commerical species. The representative plantations of initiation and sprouting second generation were selected in Mountain Yi（ E118°36′,N36°10′） and Mountain Tai （E117°19,N36°17′） of Shandong Province. To solve the problems of sprouting regeneration embarrassment, plantation structure characteristics, plant growth process and trunk form were investigated and analyzed. Results showed that： 1） Trunk height before 22 years, trunk total volume growth and the average volume growth before 17 years, and volume growth in successive years before 14 years of sprouting second generation plantation were higher than that of initiation generation, but afterwards, all indexes are lower than initiation generation. 2） Trunks of the initiation generation plantation of R. pseudoacacia L. were straight, while most of the sprouting trunks were crooked. 3） The index of the trunk bending could be used to describe the truck bending degree. According to this index, five levels, i. e. , straight truck, mainly straight truck, slightly bending truck, medium bending truck, and seriously bending truck were divided. We found that in R. pseudoacacia L.plantation medium bending and seriously bending truck trees accounted for 34.8 percent, the straight truck tree was few which only accounted for 0.86 percent, the mainly straight truck trees accounted for 33.8 percent. Based on the study of growth retardation, bad trunk form and non-timber problems with regard to the R. pseudoacacia L. sprowting regeneration plantation, we suggested that sprouting regeneration was a very important problem which required much more attentions and researches.