Nanjing is a city filled with iconic, jumbo plane trees (in Chinese, wutong). The plane trees were introduced in China by the French in the late 1800s or early 1900s to adorn their settlement in Shanghai.  Then in the late 1920s, more than 20,000 saplings were planted along Zhongshan Avenue, a road leading to the mausoleum of the anti-imperialist leader Sun Yat-sen, revered as the father of modern China. By the 1960s, it is reported that there were an estimated 200,000 such trees in Nanjing.   The green Platanus of the plane trees have become a signature of the city. Wutongs are said as supertrees by horticulturists and city planners because they are immune to urban grime and smog. And they became not just a symbol of Nanjing’s graceful beauty, but of its civic philosophy. China’s capital through multiple dynasties, Nanjing regards itself as a cultural haven. Its urban plan touts the city’s integration with mountains, rivers, and trees. According to Nanjing citizens, “They keep the whole city cool”, “The people of Nanjing grew up together with these trees,” “There is so much emotional attachment to them.” 
That did not shield them from the onslaught of development. Since the 1990s, Nanjing’s plane trees have been removed en masse to make way for urban construction projects. In 1993, more than 3000 were felled to make way for the Shanghai-Nanjing Expressway; similarly, about 200 more were removed to build Nanjing Subway Line Two in 2006. 
In March 2011, planned massive removal of trees, due to the construction of Nanjing Metro Line 3, provoked a strong opposition movement. According to the removal plan, more than 1,000 trees — mostly wutong — would be beheaded, uprooted and plunked down elsewhere to make space for six above-ground stations of Line 3 in the city center. The planned metro lines (mainly Line 3 and Line 10) were part of the infrastructure plan to improve public transportation in advance of the 2014 Youth Olympic plans. 
On 1 March 2011, Yangtse Evening Post reported that dozens of wutong trees at the cross of Zhongshan East Road and Taiping North Road were damaged, more and more Weibo users forwarded the report and the pictures with ignited anger.  On March 9, the photos were sent to Huang Jianxiang, a famous Nanjing-born sports commentator formerly employed by CCTV, who has millions of followers on Weibo. Huang passed the information to other celebrities who had lived in Nanjing, including film director Lu Chuan, hosts of television shows like Le Jia and Meng Fei, and film stars such as Yao Chen and Zhao Wei with high degrees of publicity. As celebrities posted and shared the photographs, it launched a nationwide explosion of public opinion. 
The Nanjing Municipal government has responded to the criticisms by expressing regret, but saying the removal was an 'unavoidable' consequence of constructing the subway.  And originally, the number of affected trees was yet higher: 2,600 were to be moved before discussions with subway authorities prompted a re-think.  The local authorities explained that the trees were not being felled, but rather moved for replanting. However, journalists, experts, and NGOs articulated persuasive narratives and offered an alternative perspective from the government’s, based on investigations and research. Zhu Fulin, a reporter for Nanjing Morning Post, and Cai Jianhua, a researcher from the Institute of Botany, traced what had happened to trees that had already been replanted five years ago from another construction project. They found that 80% of the trees had died after being replanted—and they broadcast this information, challenging the government’s promise that the replanted trees were still healthy. Environmental NGOs, Friends of Nature and Nanjing Green Stone, not only launched awareness campaigns but also organized activities, and worked cooperatively with media personalities, which allowed them to better coordinate their campaigns with stronger supporting data and evidence. 
On 14 March, a schoolteacher organized students to tie green ribbons around some untouched trees.  Petition letters were also addressed to the Municipal Government, some posters with the slogan “Love my old capital. Protect the plane trees”, and various catchphrases with shocking photos were spread by drivers and other activists, further amplifying the issue. Taiwan’s legislator Qiu Yi, who was also a member of the Kuomintang (KMT)’s Central Standing Committee (CSC), had heard about the tree situation through Weibo and adopted several means to oppose the plan. Facing pressure from both the online masses and Taiwan’s leadership, on March 15 the city government finally responded, saying it would improve plans to protect the trees. A subsequent press release from the Nanjing government indicated little had been done to quell concerns. On 17 March, Qiu Yi proposed to the KMT standing committee that the Association for Relations Across the Taiwan Straits and the Straits Exchange Foundation (the bodies set up by China and Taiwan to handle technical or business matters between the two sides) be used to deal with the issue. He framed protecting plane trees as respecting the collective history of “Chinese compatriots on both sides of the Strait”, suggesting that the KMT could express concerns through different channels. He directly phoned Nanjing’s mayor Ji Jianye and the Taiwan Affairs Office (TAO) of Nanjing’s municipal government. Overall, KMT’s participation politically amplified the issue as potentially negatively affecting the cross-Strait relations, which was especially concerning in the centennial year of the Xinhai Revolution.  
Nevertheless, according to the Southern Weekly, the construction of Nanjing Metro Line 3 has not involved the same degree of consultation or publication of information as of Line 2, public anger remained strong and an online call to gather in the square of the city’s library was set for 19 March.  Some government authorities, including the Public Security Bureau and the top leaders of the city, were worried about social stability. The municipal government stopped the tree removal work on late 17 March and announced the decision publicly.  The municipal government published an official document announcing all the plans and constructions should take the protection of old trees as a non-negotiable.  Two-thirds of the trees originally to be removed were saved because of Nanjing citizens’ various forms of peaceful contention.  Hundreds of residents still responded to the call to gather in the square of the city’s library, which was generally a peaceful protest despite the arrival of large numbers of public security personnel. 
On 22 March, Nanjing decided to adopt a “green assessment” system, the first in China, and the Metro Line 3 project was a pilot of the new assessment.  The protest against the removal of plane trees and the “green assessment” was later recognized as a great legacy for the city.