3种上海市常见古树粗根系分布特征及保护对策

城市古树拥有极高的文化、景观、科研价值,对其承担主要营养吸收及支撑功能的根系的养护是古树保护的重要方面也是技术难点。为研究古树根系的分布特征及相关影响因素,本文利用美国TreeRadar公司开发的树木雷达系统(TRU)对古树名木根系采用非入侵式的探测,检测了3种古树的根系水平、纵向分布特点,并重点研究了树种、树龄、硬质空间对根系分布的影响,发现银杏(Ginkgo biloba L.)、香樟Cinnamomum camphora(L.)J.Presl]、广玉兰(Magnolia grandiflora L.)三者的根系数目峰值分别在距茎干3、4~5、5m处,纵向上古树的整体根系分布深度依然是主要集中在深度120cm以上(占比65%)。银杏具有深根型的特征,而香樟和广玉兰根系水平延伸范围更大。发现硬质空间或地面可能导致根系深层延伸受阻、浅层根系密度变大,严重可致根系退化。最后结合上海特有的古树生长环境特征,从根系保护出发,本文给出了根系引导生长、生长空间特殊管控、人工助稳、根系监测等古树保护的策略。

Roots Distribution Characteristic and Protection Strategies of 3 Kinds of Ancient Trees in Shanghai

Ancient trees in urban areas are of great value in culture,landscape and scientific research.Protection of main roots that undertake the function of nutrient absorption and supporting is of great importance in conservation and management of ancient trees,but there are many technical difficulties in the process.In this paper,Tree Radar System developed by American company TreeRadar was used to detect the horizontal and vertical distribution of ancient tree roots noninvasively.Three kinds of trees were detected and factors like species,age and cemented space that had connection with roots distribution were focused on.The results indicated that the peaks of root number for Ginkgo biloba L.,Cinnamomum camphora (L.) J.Presl and Magnolia grandiflora L. appeared at 3,4-5,and 5 m away from the stem respectivly,the depth of all roots mainly concentrated beyond 120 cm (accounting for 65%).Ginkgo had deep root features,while Camphor and Magnolia grandiflora roots extended farther and wider.Cemented space might interfere with root extension.It might increase root density in shallow soil while decrease root density in deep soil and even degrade the whole root system.At last,based on the characteristics of the growth environment of ancient trees in Shanghai and the aspect of roots protection,strategies like rooting induction,growing spatial management,artificial stabilization and root monitoring were given.