平原湖区抑螺防病林池杉生长规律的研究

Growth Patterns of Taxodium ascendens Plantations for Snail Control and Schistosomiasis Prevention in Plain Lake Areas

通过对血吸虫病重疫区江汉平原池杉抑螺防病林进行观测调查和树干解析,研究探讨了平原湖区池杉的树高、胸径和材积生长规律,并建立了随年龄变化的数学模型。池杉树高早期生长快,20a之后增长速度明显下降,连年生长量和平均生长量在15a左右相交。胸径生长以4～14a最为迅速,连年生长量和平均生长量均呈先升后降趋势并在12～14a相交。材积平均生长量在前24a一直呈上升趋势,连年生长量在22a时达到最大。材积生长率和形数随树龄增加而逐渐减小,形数在6a后趋于稳定。应根据池杉生长规律,科学营建抑螺防病林,实现综合效益最大化。

A field trial of Taxodium ascendens plantation for snail control and schistosomiasis prevention in epidemic area of schistosomiasis in Jianghan Plain was analyzed based on observed data and stem analysis, growth patterns of height, DBH and volume were studied, and a mathematic model of growth changes with the tree ages. The height growth of Ta.~odium ascendens was fast in the early stage and dramatically slowed down after age of 20 years, the successive annual growth and the mean growthintersected around the age of 15. The DBH growth was most rapid during the year of 4 - 14. The successive annual growth and the mean growth revealed the same trend of rapid early growth and slow later growth, and intersected at the year of 12 - 14. The mean volume growth continued rising until the age of 24 years, and the successive annual volume growth peaked at the age of 22. The volume growth rate and the form index gradually decreased with the increase of age, the form index stabilized since the age of 6. Establishment of plantations for snail control and schistosomiasis prevention should be based on the identified growth patterns of Taxodium distichum to maximize the comprehensive benefits.