Text by Yu Jinyi & Cao Beiyi Photos by Ni Na & Zhao Qin

Ancient and rare trees span the past and present. They witness the great vicissitude of a city. They are regarded as scenic spots, historical and cultural symbols, as well as living fossils of a city. According to the statistics from the Wild-life Protection Office of Wuhan Municipal Bureau of Gardening and Forestry (WMBGF), Wuhan now has 1691 ancient and rare trees. Are these trees in a good condition? On December 2, 2018, WMBGF conducted a total physical checkup for those aged around 300 years in the downtown areas. Very soon, this program will examine the ancient and rare trees over 500 years of age in the remaining urban areas. This was the first time the Wuhan government had conducted a physical checkup for ancient and rare trees with advanced equipment.

The most well-known ancient tree in Wuhan is a ginkgo tree called the “Hanyang Tree,” which has grown at No. 12, Phoenix Alley in Hanyang District for over 530 years. It is said that it got its name from a poem titled “Yellow Crane Tower” by the famous Tang-poet Cui Hao (704-754), “By sunlit river, Hanyang trees can be counted one by one; On Parrot Islet sweet green grass grows fast and thick.”

An expert checks the trunk with a needle-ended instrument. 专家用针测仪检测树干。

On December 2, 2018, Ding Zhaoquan, General Engineer of Wuhan Institute of Landscape Architecture (WILA), picked up a leaf from the ground after walking around the “Hanyang Tree.” “The tree has lush foliage, but its leaves are smaller than those of the past few years. Broken branches were rare in the past, but now they are common,” Ding said, “The climate change, flooding, and drought in recent years have been detrimental to its growth.” One researcher pierced into the thick trunk with a needle-ended instrument. This long needle, with a diameter of only 1.5mm, thrusts itself straight into the middle of the trunk, capturing the spectrum ofits rings by the resistance formed between the tree spans. A healthy tree’s spectrum goes even and steady, without any sharp rises or falls. An unhealthy tree, with any hollows or decay in the trunk, can be detected through the spectrum.

Soon, a “cardiogram” was printed out. However, a closer examination required an instrument called a “Tree Section Imaging System.” One researcher attached 12 sensors to the trunk of the tree, which produces images on the condition of any one of them being hit. Shi Hongwen, a senior engineer at WILA, said, “It is like a CT scan on the section of the trunk to check the degree of decay inside the tree, so that different protective measures can be taken.”

About half an hour later, WILA reported the result: The tree was basically in good condition, but some decaying parts could be detected from inside the trunk. Next, they invited some experts in this field to jointly carry out a set of protective measures.

Shi also said that if a tree was in a good condition, the result would come out in a day or two, while if a tree was in a seriously ill condition, it required a 7-to-10-day consultation from experts before the result could be released.

The checkup covers a wide variety of trees, such as the cypress co-planted by Mao Zedong and Kim Il Sung, the Chinese pine planted by Mao Zedong during his Wuhan trip, the camphor planted by Zhou Enlai, and Osmanthus and Chinese viburnum planted by Dong Biwu and Deng Xiaoping. Among them, the oldest tree in downtown Wuhan is a juniper which boasts over 900 years of life, with the “Hanyang Tree” being the second oldest.

In contrast to other first-tier cities in China, Wuhan enjoys less plentiful resources of ancient and rare trees. Ding noted that the high temperature and moisture levels from the local climate and frequent disasters including harmful pests and lightning are a threat to the growth of trees, and Wuhan has been a place of military importance so large numbers of ancient trees were ruined in the raging battles. The development of urbanization, human activities such as deforestation and construction damage as well as deteriorating ecological environment all pose a danger to their growth.

In recent years, the Wuhan Government has placed importance on the protection of ancient and rare trees. Some relevant authorities have coordinated with construction companies in advance in projects where ancient and rare trees are involved.

For example, when the construction of the Wuhan Yangtze River tunnel began, a ginkgo stood right in the way of the Tianjin Road Exit. The construction company required the tree to be removed. However, authorities from gardening and forestry departments found that the tree root was buried beneath the cemented ground, and it didn’t grow very well. If it was moved elsewhere, it would likely die. More importantly, this ginkgo had witnessed the history of Tianjin Road, so the tree would lose its meaning if it was moved elsewhere. WMBGF believed that the history of Tianjin Road could be neither seen nor felt without this ginkgo. Finally, the construction company redesigned the underground pipelines and the exit to save the tree.

Similarly, in the original design of the expressway in the north of the Yangtze River in Wuhan, a lower ramp ran over a Chinese ash with over 100 years of history. After consultation with authorities from gardening and forestry departments, the construction company redesigned the ramp to bypass the tree—and some drains were also built around the tree in order to keep it from being polluted by runoff.

(Translation: Wang Wen)

An expert conducts a physical checkup by recording the vibration frequency from hitting the sensors. 专家通过设备记录传感器敲击的震动频率为古树体检。

“做CT”、改设计——武汉这样保护古树名木

文/余瑾毅 曹贝宜摄影/倪娜 赵琴

古树名木，镌刻着岁月的年轮，见证着城市的变迁。它是城市风景，也是历史文化的延续，被誉为城市历史“活化石”。中国武汉市园林和林业局野保处数据显示，该市古树名木共有1691株。这些“岁月老人”身体是否康健？2018年12月2日，该市园林和林业局从中心城区开始，对300年以上的古树名木进行体检，后续还会将体检范围扩大至新城区500年以上的古树名木。这是武汉首次采用精密仪器为古树名木体检。

“晴川历历汉阳树，芳草萋萋鹦鹉洲。”位于武汉市汉阳区凤凰巷12号的一株银杏至今已逾530岁，因唐代诗人崔颢的诗句而得名“汉阳树”，是武汉最有名的古树。

WILA carries out a general physical checkup for the 530-year-old “Hanyang Tree” by using advanced equipment such as the needleended instrument and elastic-wave tree section imaging device. 武汉市园林科学研究院通过树木针测仪和弹性波树木断层成像诊断仪等先进设备，为已有530多年的“汉阳树”进行全面体检。

12月2日，园林科研院总工程师丁昭全围绕着“汉阳树”慢慢走了一圈，从地上捡起一片落叶：“树形比较饱满，但叶子确实比前几年略小。以前几乎没有断枝，现在有了很多断枝。这可能和近几年的气候有关，洪涝和干旱都不利于古树生长。”检测人员拿出专用设备针测仪刺入树干。这根直径1.5毫米的针直刺进树心，根据树木年轮间受到的阻力形成波谱，用于判断树干的健康状况。健康的树，波谱比较平滑均衡，不会突然升高或下降。如树干内有空洞腐朽等异常情况，波谱都会反映出来。

很快，一张“心电图”打印出来。更细致的检测需要树木断层成像系统。检测人员在树干上挂上12个传感器，敲击其中一个传感器，则会传来图像。高级工程师史红文说，这就像CT，对树干断面进行扫描，检测树木腐烂坏死状况，为养护措施提供依据。

“体检”约半小时后，武汉市园林科学研究院出具了“汉阳树”的体检结果：整体生长正常，但树干中有部分腐朽。下一步，将邀请国内古树保护领域的权威专家会商，制定一套科学的综合保护措施。

史红文表示，生长健康的树木检测结果可在一两天内得知，而受损较严重的，则需要专家会诊，大约需要7天至10天。

毛泽东与金日成共同栽种的龙柏、毛泽东下榻此处栽种的油松、周恩来栽种的樟树、董必武和邓小平所栽的桂花和木本绣球等，都在本次体检范围之内。年龄最大的古树是一株桧柏，有900余年历史，是武汉市中心城区内最老的树，“汉阳树”年龄仅次于它。

相较全国其他重点城市，武汉市的古树名木资源并不丰富。丁昭全说，武汉的气候高温高湿，自然灾害如病虫、雷电较多，不利于树木长久生长，加之武汉历来是兵家必争之地，战乱炮火导致许多古树名木遭受破坏。随着城市发展，大兴土木等人为因素也成为古树名木健康成长的隐患。机械损伤、生态环境破坏都会影响古树名木的生存。

近年，武汉市重视古树名木保护，项目建设如涉及古树名木，相关单位会提前与施工建设单位联系、协调。

例如，武汉开建长江隧道时，在天津路出口处，一株百年银杏挡住出口通道，建设方要求移走银杏。园林部门查看后发现，银杏周围几乎全是水泥硬铺装，树木长势也不旺，移栽几乎没有成活几率。更重要的是，该银杏见证的是天津路一带的历史，移栽后再无任何意义。武汉市园林局认为，没有这株银杏，天津路的历史就“看不见、摸不着了”。最终，建设方更改了地下管线和隧道出口设计，保住了这株古银杏。

此类举措在今年通车的江北快速路上也有体现。原设计方案中，该路下闸道正好经过一棵100多岁的枫杨。经园林部门沟通后，建设方最终更改方案，扩大闸道弧度，避开了古树，并在古树四周做了排水沟，为枫杨排除了健康隐患。