Why are all the trees in Hainan red?

Egrets are common in mountain streams, lakes, beaches and mangroves. They are summer migratory birds in Dongzhai Port. Wings and tails have green luster, females are slightly smaller than males, and young birds have brown longitudinal stripes.

Although newspapers are close at hand, the mangrove forest in Dongzhaigang, which lives in the southeast corner of Haikou, is still a familiar and unfamiliar existence for many "old Haikou". Familiarity is due to geographical proximity. After all, it is only 30 kilometers from Haikou City to Yanfeng Town where Dongzhaigang Mangroves are located. Strangeness is because of "remoteness" in understanding. Most people have seen this "marine forest" that has been quietly undertaking to maintain and improve the ecological environment of Dongzhai Port and even Haikou for hundreds of years, but recently they have seen less. From the appearance, mangroves are not red. Why is there the word "red" in the name? Why is there such a large area of mangroves in Dongzhai Port? What are the "secrets" of mangrove plants in seawater immersion? Besides mangroves, what other life exists in this unique mangrove ecosystem, and what is their relationship with mangroves? ……

In order to find out, in early August, the reporter followed the staff of Hainan Dongzhaigang National Nature Reserve Administration and went in and out of the mangrove core area of Dongzhaigang several times, trying to show "the mangrove you don't know".

Reporter Liu Ji

Trainee reporter Lin Yuhong/Wen

Reporter's sheet is just right/picture

Reporter goes deep into the core 1

Keywords Meng

The respiratory roots of some mangroves are very similar to knees.

Just after 8 am on August 3rd, Wang Shijun was busy in the nursery of Hainan Dongzhaigang National Nature Reserve Administration (hereinafter referred to as "the Administration"), checking the growth of red plum (a mangrove plant) seedlings in the nursery again and again. These red plum seedlings were slowly cultivated by the Administration after 20 13. Hongmei is warm, but fortunately, the winter in Haikou has not been too cold in the past two years. It has survived and blossomed this year. When Wang Shijun watched his red olive grow up, he couldn't help laughing.

Wang Shijun is one of the few "old people" in the Authority. He will retire next year. He is one of the only employees of the Administration who have persisted since the establishment of 1980 Dongzhaigang Nature Reserve. "When I retire next year, the only thing I can't worry about is these red plum seedlings." Wang Shijun is worried for a reason. At present, there are only 14 evergreen trees in Dadun Village of Lingshui and Tielu Port of Sanya in China, which are the most endangered mangrove plants in China. Before Dongzhai Port, 17 trees were introduced, and 10 trees survived. Unfortunately, they all froze to death in the cold wave in 2008. "Big trees are afraid of cold, and these small trees,

For the "layman" reporter, the nursery managed by Wang Shijun is undoubtedly an excellent place to learn about mangrove plants. In addition to the precious red plum seedlings, there are many representative mangrove plants growing on the beach around the nursery, and Wang Shijun is also happy to be a guest commentator. "This is a sea lily, how to tell? First look at the appearance. You see, this kind of tree grows very tall and has a full crown. Secondly, look at the bark. There are some lenticels on the bark of OceanLotus. Look at the roots again. Hailian has a very developed knee-shaped respiratory root. At low tide, the shape of the respiratory roots exposed on the beach is very similar to our knees. Isn't it cute? "

The reporter noticed that most mangrove plants in the nursery have respiratory roots, which are knee-shaped and bamboo shoots. Breathing roots break through the ground, absorbing air and water and supplying nutrients to trees. In addition, many trees will grow pillar roots on their branches and directly insert them into the mud on the beach to fully support the dense crown and become a stable support against wind and waves. "The root depth of terrestrial plants is similar to the height of trees, but even if mangrove plants are five or six meters high, the root depth is generally no more than 40 cm, and other means are needed to resist the wind and waves." Wang Shijun said.

Keyword interest

If you don't eat sea salt, you will have a baby.

Standing on the trestle in the nursery, looking at a small piece of lotus forest next to the nursery, with its dense and varied knee-shaped respiratory roots, is really "naive" as Wang Shijun said, which is quite interesting. These characteristics of sea lily are obviously passed on to the species of sea lily, which is a hybrid of sea lily and another mangrove plant Bruguiera gymnorrhiza. This rare and endangered plant, which is only distributed naturally in Qinglan Port in Wenchang and Tielu Port in Sanya, China, not only has developed knee-shaped respiratory roots, but also has dense lenticels on its bark for breathing. It takes a lot of courage for people with intensive phobia to look at bark again.

"Whether it is red plum, sea lily or pointed petal sea lily, whether it is seedlings or trees, it looks green. Why is it called mangrove? " Wang Shijun didn't rush to answer the reporter's question, but walked quickly to the sea lotus whose bark was cut open and said, "Many people have this question. As for the reason, you see, the bark of this tree was uncovered when we were doing scientific research a few days ago. Is the trunk red now? This is why mangroves are called mangroves. " It turns out that mangrove plants are periodically submerged by seawater and the bark contains tannic acid. If it is cut down or destroyed, tannic acid will oxidize when it meets air, making the trunk red. This is the origin of the name "mangrove".

Mangrove plants grow in a special environment, and the fluctuation of seawater can easily wash away seeds. Therefore, the fruits of mangroves do not germinate on the ground, but continue to absorb the nutrition of big trees and grow into seedlings on the mother trees, which is called "viviparous" phenomenon academically. After the "fetus" matures, the seeds with tiny branches and leaves will leave the trees and be scattered on the beach. Go with the flow and meet the right place, they will take root and sprout, and "settle down." Because this special way of reproduction is like a mammal holding a baby, many people call mangroves "trees with babies".