How should the National Botanical Garden be built?
China News Weekly reporter / Du Wei
Published in the 1033rd issue of "China News Weekly" on February 28, 2022
On January 4, 2022, the State Council approved the establishment of a National Botanical Garden in Beijing.
At the same time, the construction of the national botanical garden system will also be launched in Beijing, Guangzhou and other places.
Unlike national parks that focus on in situ conservation, one of the main tasks of the National Botanical Garden is ex situ conservation.
Xu Zaifu was the director of the Xishuangbanna Tropical Botanical Garden of the Chinese Academy of Sciences and the honorary chairman of the Botanical Garden Branch of the Chinese Botanical Society. He wrote the first book on ex situ conservation of plants in China.
He told China News Weekly that the most urgent need for building a national botanical garden today is to improve the level and effectiveness of ex situ protection of plants. ".
Botanical gardens should be located where species are most abundant
The Beijing Botanical Garden is located near the Reclining Buddha Temple at the foot of Fragrant Mountain, covering an area of 231 hectares.
According to the official website, its plant exhibition area is divided into ornamental plant area, arboretum and greenhouse area, collecting and displaying more than 10,000 species (including varieties) of various plants. Orchid) Botanical Garden.
Across the street from the Beijing Botanical Garden is the Institute of Botany, Chinese Academy of Sciences. Its botanical garden covers an area of 74 hectares and collects and preserves more than 7,000 species (varieties).
Both parks were approved to be established in 1956, commonly known as "North Park" and "South Park".
The National Botanical Garden established in Beijing this time is based on the construction of the two gardens, merged, unified planning, and unified listing. The planned area is about 600 hectares.
According to Wang Kang, curator of the Science Museum of Beijing Botanical Garden, there are usually four functions of botanical gardens in the world: horticultural display, scientific popularization, scientific research and species protection. Different botanical gardens have different functions.
Before the establishment of the National Botanical Garden, the main functions of the Beijing Botanical Garden ("North Garden") were horticultural display and popular science education. The mission of the Chinese Academy of Sciences Botanical Garden was mainly scientific research and species protection.
The main purpose of the establishment of the National Botanical Garden is to strengthen the ex situ protection of plants.
The so-called ex situ conservation refers to the purpose of conservation, which can refer to the cultivation and preservation of live plants in botanical gardens, or the establishment of genebanks to preserve plant seeds, tissues, and organs.
Ex situ conservation is not simply to dig up plants and plant them in the park. The most conventional and effective method is to introduce and cultivate and establish special plant gardens (districts).
Wen Xiangying, senior engineer of the South China Botanical Garden of the Chinese Academy of Sciences and director of the China Office of the International Botanical Garden Conservation Alliance (BGCI), told China News Weekly that ex situ conservation is the priority and key protection is "3E" plants, that is, endangered (Endangered), endemic (Endangered), endemic ( Endemic), plants with economic value.
At present, there are more than 2,000 botanical gardens in the world, preserving more than 100,000 species of plants, accounting for 30% of the world's plant species.
China has more than 36,000 species of higher plants, nearly 200 botanical gardens, and 23,000 species of plants.
In other words, the number of higher plants in China accounts for about 1/10 of the world, and the number of botanical gardens accounts for about 1/10 of the total number of botanical gardens in the world, and the proportions of the two are roughly equal.
In China, the ex situ conservation of plant species has reached 60% of the native plant species.
Botanical gardens have different functions over time.
In 1985, the first international conference on "Botanical Gardens and the World Nature Conservation Strategy" was held in Spain, which closely linked botanical gardens with the conservation of biodiversity in the world, making ex situ conservation an increasingly important mission of botanical gardens.
In recent years, the comprehensive conservation concept combining in situ conservation, ex situ conservation and plant return has been increasingly valued and applied to the conservation of plant diversity.
Due to the diversity and complexity of factors threatening biodiversity, no single conservation approach is likely to be successful.
These concepts have strongly promoted the development of the botanical garden.
Since the late 1980s, the number of botanical gardens in China has grown rapidly from about 70 to about 200 around 2005, with an average increase of one every three months.
Wang Kang said that the establishment of the National Botanical Garden in Beijing has at least three considerations. First, it is a symbol of national image; second, considering the needs of popular science, the "North Garden" has an annual passenger flow of 4 million; third, the National Botanical Garden in Beijing is a collection of , It is an ideal place to preserve the representative plants of the northern temperate zone. In addition, there is the blessing of the "national team" of the Institute of Botany of the Chinese Academy of Sciences.
Xu Zaifu mentioned in several articles that there is a serious imbalance between China's botanical gardens and the distribution of plant diversity. The richer the species, the fewer botanical gardens are distributed.
The development of Chinese botanical gardens is mainly concentrated in some large and medium-sized cities in the developed coastal areas of the central and eastern regions, and the investment is often hundreds of millions or even more than one billion.
And in places with richer biodiversity and more unique ecosystems, there are few or no botanical gardens.
About 20% of the first batch of key protected plants in the country have not been preserved in situ, and most of them are distributed in alpine, sub-alpine, frigid, cold temperate zones, as well as in arid and semi-arid regions.
This is one of the reasons why the preservation rate of the first batch of key protected plants hovers around 80%.
Similar problems exist in the distribution pattern of botanical gardens worldwide.
There are 28,000 plant species in Europe, America and North America, less than 1/10 of the world's total plant species, but there are about 900 botanical gardens, accounting for about half of the world's total.
In South America, where the economy is less developed, there are 90,000 species of plants and only nearly 100 botanical gardens.
Xu Zaifu believes that from the perspective of scientific significance and ex situ conservation, considering habitats and pollination issues such as insects and birds, the site selection of botanical gardens should be far away from big cities, and choose places rich in species, preferably close to a nature reserve. area or close to large areas of natural vegetation.
In this way, in situ protection, ex situ protection, and introduction and return to nature can be combined, and the "terroir domestication" and "artificial domestication" caused by too large ecological environment differences and too many human interventions can be avoided.
In 1959, under the leadership of botanist Cai Xitao, Xishuangbanna Tropical Botanical Garden was established on "Huludao" in the tropical jungle of Xishuangbanna in southern Yunnan. A botanical garden with more than 10,000 plant species cultivated in the open field.
The establishment of the National Botanical Garden in Beijing this time has also raised questions about the high latitude of Beijing and the limited species of plants that can be cultivated and grow well outdoors.
In this regard, Wang Kang explained that, excluding species, only in terms of species, the South and North Gardens of the National Botanical Garden have collected and preserved thousands of plant species.
In the future, the National Botanical Garden will protect plants in the Northeast, North and Northwest China, namely the "Three Norths" and the same latitude and similar climate types in the world.
Some plants that cannot be cultivated in the open field will be placed in greenhouses or experimental stations will be set up in the suburbs of Beijing where plants are suitable for growth.
Xu Zaifu said that the open field is the main place for ex situ conservation of plants, and the greenhouse can only be a supplementary measure, and it is more of a popular science display, and it is difficult to truly achieve the purpose of biodiversity conservation.
"The diversity of plants in the northern temperate zone is still relatively poor." An industry expert analyzed that the positioning of the National Botanical Garden in Beijing should focus on the cultivation of northern plants in the open field. If a large-scale greenhouse is built, it will also bring huge costs. .
Among the botanical gardens around the world, there are many cases established in the capital.
Xu Zaifu explained that this is because in the early days of Europe and the United States, botanical gardens did not undertake the function of biodiversity conservation.
In addition, with the process of urbanization, the suburb where the botanical garden was originally built has become an urban area, which is caused by objective reasons.
According to the plan of the State Forestry and Grassland Administration, in addition to the establishment of a national botanical garden in Beijing, regional national botanical gardens will also be built in Guangzhou and other places in the future.
The construction of the national botanical garden system will adopt a combination of integration and new construction, with regional national botanical gardens representing typical climatic zones and typical vegetation characteristics as the main structure.
Most of the botanical gardens in China are built in cities, and the area is small, which is also an important factor limiting the ex situ conservation of plants.
According to the statistics of more than 120 botanical gardens by Xu Zaifu and others in 2008, small botanical gardens with an area of less than 40 hectares accounted for 40% of the total, and botanical gardens with an area of more than 100 hectares accounted for about 1/3.
A considerable part of all botanical gardens are urban parks.
"A botanical garden with a small area in a city does not have to undertake the task of biodiversity protection, and mainly performs the function of popular science." Xu Zaifu said.
According to the plan, the construction of the National Botanical Garden will include the mountains and forests on the north side of the "North Garden", bringing the total area of the Botanical Garden to nearly 600 hectares.
Improving the effectiveness of ex situ conservation
In Xu Zaifu's view, ex situ conservation of plants must follow at least three basic principles, namely, "climate similarity" of light, temperature and water humidity between the migration site and the original plant site; "habitat similarity" such as topography, landform and soil matrix; "Plant communities are similar" composed of plants and microorganisms.
For example, in the area of 600 meters above sea level in Xishuangbanna Botanical Garden, the native rare and endangered plants such as Feather floss and Yunnan winged tree in the mountains above 1200 meters above sea level are cultivated. will not bear fruit.
Xu Zaifu said that the ex situ conservation of domestic threatened plants is still in the stage of species collection and conservation, and most of the collected seeds come from individual natural populations and a few mother plants.
"It is often just to collect one strain and then propagate it", which cannot contain all the genetic diversity.
If at least 10 individuals are protected ex situ in a population as the evaluation standard, 54% of the species in domestic botanical gardens do not meet the standard, and the number of species with only 1 to 5 plants preserved accounts for about 45% of the total.
And a considerable proportion of species are introduced to each other between botanical gardens.
They are prone to inbreeding and inbreeding recession, similar to inbreeding.
When individuals from different populations are planted together, it is possible to produce hybrid decline, and it is impossible to protect the genetic diversity of each population.
Furthermore, due to the limited land, manpower, and funds of botanical gardens, many botanical gardens grow a small number of each type of plant, which is also the key to ex situ conservation requiring a larger area of botanical gardens.
Sun Weibang, deputy director of the Ex situ Conservation Committee of the China Wild Plant Protection Association and director of the Kunming Botanical Garden, and his team have been engaged in the research and practice of the protection of very small populations of wild plants since 2004.
He explained to "China News Weekly" that the rescue and protection of threatened species is a systematic project, including systematic field investigations, establishment of protected areas for species or populations distributed outside protected areas, reproductive biology and artificial reproduction. Technical research, in situ (ex situ) conservation, etc.
Take Yangbi maple, a wild plant with a very small population in Yunnan as an example. This is a plant with hairy leaves that looks like a fat palm and a pair of fruit wings on its fruit. It is named after it was found in Yangbi County, Dali, Yunnan.
Initially there were only 5 in the wild.
After harvesting a batch of seeds, Sun Weibang led the team to break through the key artificial propagation technology and artificially cultivated more than 1,600 maple seedlings in 2009.
"We need to compare the genetic diversity and genetic structure of more than 1,000 seedlings with 5 in the wild, to ensure how many plants can be planted to maintain the genetic diversity of this species, and to establish a minimum sampling strategy."
Sun Weibang believes that what is more important now is to find out the "family" and determine which species need rescue protection.
An assessment of 35,784 species of wild higher plants in China in 2017 showed that the threatened ratio was 15%-20%, and 4,804 species lacked data.
About 1,500 threatened plant species are conserved ex situ in the China Botanical Garden, accounting for about 39% of the native threatened plant species.
In Sun Weibang's view, these figures are instructive, but "not necessarily completely accurate", so field investigations must be carried out.
For threatened plants, it is necessary to further determine which should be prioritized for protection.
Assessing the effectiveness of ex situ conservation is also a lengthy process.
The canopy tree with a height of more than 40 meters, a peculiar canopy shape, and a "tall like a canopy" is a very small species endemic to local areas of Yunnan.
In 1983, the Kunming Botanical Garden carried out ex situ conservation of Cangai tree seedlings from Xichou County, Yunnan.
It was not until 2013 that the introduced Canopy tree bloomed for the first time.
"Whether the ex situ protection is successful depends first on whether it can bloom and bear fruit." Sun Weibang said that most of the wild plants in the very small population are woody plants, and the Qiaojia five needles pine, which is only distributed in Qiaojia County, Yunnan, is protected in Kunming Botanical Garden ex situ. It takes 12 years to bloom and bear fruit, and it takes 8 years for Yangbi maple.
A doctoral student of Sun Weibang spent five years researching the genetic diversity of ex situ conservation of canopy trees.
Kunming Botanical Garden and South China Botanical Garden have preserved 70.27% and 32.43% of the genetic diversity of wild canopy trees respectively. Compared with the two, the former has done a good job.
Compared with ex situ conservation, near-situ conservation is considered to be a measure whose conservation effectiveness is much higher than the former.
The so-called near-earth protection refers to the establishment of protection bases in the near-earth with similar protected plant habitats.
According to Xu Zaifu's research, the growth adaptability and average annual growth of the same plant species in near-situ conservation are in most cases much higher than ex-situ conservation.
Xu Zaifu said that the cost of near-ground protection is lower, which is why the botanical garden should be set up as close to nature as possible.
No plant in the world has really returned to success
In 2002, Wen Xiangying went to Missouri State University - St. Louis campus to study abroad.
In 2003, a friend in China asked her to go to the world-class Missouri Botanical Garden to find a plant material.
The Missouri Botanical Garden has a history of more than 160 years and is a holy place for plant protection worldwide.
Afterwards, the park management staff provided Wen Xiangying with detailed relevant information, "including when the plant was introduced, where is it planted in the botanical garden, how many plants are there, how are they growing, which plants are no longer in the botanical garden, the reasons for not being there, work The staff can answer clearly." Wen Xiangying said that many well-known botanical gardens abroad manage the plants collected and preserved in the gardens very well, and the file information is very clear, "Although many botanical gardens in China may collect thousands of species or even more than one There are thousands of species, but how many are alive and how they are alive is not particularly clear. There is a phenomenon of 'heavy introduction and light management'. There is still a certain gap between domestic and foreign botanical gardens in the management of introduced and collected plants."
The establishment of a scientific record management system for botanical gardens was first proposed by the International Botanical Garden Conservation Union (BGCI).
But up to now, a few botanical gardens in China except the Chinese Academy of Sciences as the competent department have established a scientific record system. "Most botanical gardens have only one name for the plant records, and sometimes hang a sign, which lacks systematic records."
Xu Zaifu said, "Even a scientific record system has not been established. How do you evaluate the effectiveness of ex situ conservation, how do you provide scientific basis for issues such as the sustainable use of plants, and how do you develop popular science education?"
Wen Xiangying said that many botanical gardens in China lack the archives records of plants collected and preserved. There are many reasons: First, in the past, they did not realize the value and function of ex situ conservation plants, which led to not paying enough attention to the related work; second, Some botanical gardens may originally have plant file records, but due to omissions in the management of the botanical gardens, rapid staff replacement, and improper work handover, the files are lost.
But recently, some botanical gardens, especially new botanical gardens, have begun to pay attention to this aspect.
Talent is another issue.
For botanical gardens, traditional plant taxonomy is the most basic discipline required for the work of botanical gardens, which is directly related to the cultivation of plants in the garden and the effectiveness of ex situ conservation.
Due to the long period of research on traditional plant taxonomy, it is necessary to sit on the bench, publishing articles is not fast, and the impact factor of articles is not high. Under the trend of too much emphasis on the number of SCI papers, the cultivation of plant taxonomy talents in colleges and universities is facing a crisis.
Wang Kang said frankly that after the establishment of the National Botanical Garden, due to the transformation of functional positioning, the supply of talents, the upgrading of laboratories and equipment are all challenges.
At present, there are only about ten talents in plant taxonomy in the Beijing Botanical Garden ("North Garden").
The ultimate goal of introducing cultivated plants in botanical gardens is to return them to nature.
Plant return is more difficult and more expensive than ex situ conservation.
Once plants are returned to nature, management and monitoring are two major challenges.
Wen Xiangying's BGCI will provide three to five years of funding for each species under protection, ranging from £24,000 to £40,000.
Cooperative institutions such as botanical gardens and forestry departments also have corresponding funds, but for plant diversity protection, the funds are still insufficient.
Assessing the success of population regression is also a long-term process.
By the end of 2020, domestic botanical gardens had carried out about 300 plant return and introduction projects, involving 206 species.
Sun Weibang explained that the criteria for the success of plants returning to nature is that the population should be able to regenerate naturally, be harmless to the habitat, and be able to participate in the ecological process of the ecosystem in which it resides.
In this sense, there is no successful case of plant return in the world.
Xu Zaifu believes that domestic botanical gardens should be properly positioned according to their foundations and resources, and should not blindly pursue introduction and cultivation, and display the number of plant species.
Sun Weibang said that the botanical garden should fully consider the purpose of collecting and preserving species when formulating a species collection and conservation strategy.
For domestic botanical gardens, their own collection strategies and ex situ conservation strategies should be considered.
"It is necessary to think about the purpose of collecting each plant, whether it is used for scientific research, species conservation, or scientific dissemination, resource utilization, and ensuring the safety of regional national strategic plant resources. Many botanical gardens in China seem to have not seriously thought about this issue."
"China News Weekly" Issue 8, 2022
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