银杏树落叶的相关因素分析

银杏树作为成都常见的城市绿化美化树种,其叶片的衰老、脱落对城市景观、环境、交通等方面具有一定的影响。为了探明成都银杏树秋季落叶规律及其影响因素,合理发挥银杏树的综合效益,以四川大学校内丰富的银杏树资源为研究对象,探究了土壤pH、土壤表层温度对落叶的影响,通过对银杏树不同部位叶片图片的RGB值测定,分析了银杏树落叶时间及空间规律。结果表明:秋季银杏叶片正常的衰老、脱落与土壤的pH、土壤表层温度显著相关。在试验区土壤pH5.8~6.3时,随着土壤pH的增大,银杏树叶片中叶绿素的含量逐渐下降,而其落叶率在逐渐增长,且pH5.8~6.1落叶率的增长速度比pH6.1~6.3增长速度快;试验期间,试验区土壤表层温度基本在17.0~20.5℃,随着土壤表层温度的升高,落叶率在不断增长;同时通过对不同区域银杏树叶片相片的RGB值分析发现:银杏树叶片在衰老、脱落过程中叶绿素逐渐降解,叶色逐渐变黄,且就同一棵银杏树来说叶片首先从下部开始衰老、脱落。不同部位叶片衰老、脱落受土壤表层温度、土壤pH影响程度也有所不同,基本规律一致,即银杏树中部、下部叶片衰老程度随着土壤表层温度的增大而提速,随土壤pH的增大也在逐渐提速,而银杏树上部叶片的衰老、脱落与土壤表层温度、土壤pH相关性不显著。研究成果可以用于城市银杏绿化区域,尤其是主要行道银杏树的落叶时间调节,优化城市银杏的绿化与景观效果,降低其对交通等方面的不利影响,提高城市银杏栽种的综合效益。

Related Factors Analysis on Ginkgo Biloba Leaves

Ginkgo Biloba is one of the most common street afforestation tree species in Chengdu city ,its leaf se‐nescence and fall off have some effect on the urban landscape ,the environment and the transportation .In order to find out the deciduous rule of the Ginkgo Biloba in Chengdu ,the influence factors of the fallen leaves to make full use of the Ginkgo Biloba ,some rich resources of Ginkgo Biloba in Sichuan university were used to explore whether soil pH and soil surface temperature have some effect on the Ginkgo Biloba leaves ,and to find out the deciduous rule of the Ginkgo Biloba by analyzing the RGB value of the Ginkgo Biloba leaves from the different parts .The results showed that the decline of Ginkgo Biloba leaf fall off ,the soil pH and soil temperature had obvious relevance .Under the soil pH 5 .8~6 .3 ,the content of chlorophyll in Ginkgo Biloba leaves was gradu‐ally falling ,with the increasing of soil pH in the range ,while the defoliation rate was gradually increased .Un‐der the pH 5 .8~6 .1 ,its growth rate was faster than the pH6 .1~6 .3 .Under the soil surface temperature 17 . 0~20 .5 ℃ ,defoliation rate of Ginkgo Biloba was gradually growing with the increasing of soil temperature .At the same time ,through the RGB value of Ginkgo Biloba leaves of image analysis in different regions ,plant leaf chlorophyll gradually degraded in the process of aging and fall off ,leaves turned yellow gradually .And the leaves of Ginkgo Biloba in lower part fall off faster than other parts .The fallen leaves which were from differ‐ent parts of the tree affected by soil temperature and soil pH were different .In general ,the defoliation rate of the tree in the middle and lower increased with the increasing of soil temperature and soil pH ,but the defolia‐tion rate in the upper had no significant correlation between the soil surface temperature and soil pH .The re‐search results could be used for city Ginkgo Biloba green area ,especially the main series of Ginkgo Biloba leaves time adjustment ,optimization of urban greening and landscape effect of ginkgo .It could reduce the impacts on the traffic and improve the comprehensive benefit of city Ginkgo Biloba plant .