Abstract:

In order to explore some causes why pine needles turned yellow and many Chinese pine trees gradually died at Tiananmen Square in Beijing, China in spring 2010, a field investigation was conducted on the external morphology and the root characteristics of Chinese pine, and meanwhile soil physical and chemical properties and site conditions were also investigated and analyzed. It is found that for most of Chinese pines trees, the pine needles of their whole plants turned yellow, their fine roots withered and shriveled, and mycorhiza were rotten and died. The high salt content was found in surface soils, and the roots absorbed the large amounts of salts and lost the function of absorbing water and nutrients, which led to the emergence of yellow pine needles and the death of the whole plant. Some factors (such as small growth space, high soil density, poor soil ventilation and heat radiation) were not in favour of normal growth of Chinese pine. Moreover, a great amount of snow-melting agent was applied around Chinese pine at the Tiananmen Square after snow in winter 2009, which was a direct cause leading to the death of Chinese pine. In order to protect the achievement in afforestation and visual effects, the corresponding technical measures and suggestions were presented to prevent the hazards of snow-melting agent and to overcome the current status of adverse site conditions.