Cactus in desert

  Not as fruitful as a fruit tree, not as splendid as a flower, but a cactus grows in every desolate place and spits out new green even in arid soil. It is a “life-saving tree” in the desert, but after being transplanted elsewhere, it has unexpectedly become a biological “invader”.
Water storage experts from America

  According to the data, the “hometown” of cactus is in the Americas, mainly distributed in some plateaus, islands, mountains and desert areas. The cactus family is a large family with thousands of members. The difference in their appearance is mainly manifested in the difference of stems, which are mostly columnar or palm-shaped, small like sand and gravel, and large like giant columns. Some of the surfaces are smooth, some are nodules, some are concave, some are spherical… Most of them live in desert areas, and a few grow in tropical areas, such as some common species of Epiphyllum and Crab.
  The reason why it can thrive in the arid climate of the desert is because the leaves of the cactus degenerate into thorns, which greatly reduces the transpiration area and makes the water in the body not easy to dissipate. The green fleshy stems are thick and horny and waxy on the surface, which not only stores water, but also replaces leaves for photosynthesis. This plant opens its stomata at night to absorb carbon dioxide, and during the day closes its stomata (to prevent water loss), while still using the carbon dioxide collected at night for photosynthesis. Through this process, the water lost by transpiration during the day can be avoided.
  For walkers in the desert, the cactus is a life-saving tree. Scientists did an experiment. After pulling out a cactus and weighing 37.5 kilograms, it was thrown into a corner for 6 years and weighed again, and the weight was 26.5 kilograms. That is to say, it has used its own reserves over the years and only consumed 11 kilograms without drinking a sip of water. If it is replaced with other green plants, it is estimated that it has already become a specimen. Cacti are not only water-storage experts, but also water-saving models. In the desert, a cactus 15 meters to 20 meters high can store more than two tons of water. Amazingly, the seeds of a cactus contain enough water and nutrients to survive for months even without the parent. In addition, cacti can also reproduce by using the daughter balls produced on the mother plant, and these daughter balls can take root and continue to survive when they fall into the ground.
  Mexico is the world-famous “country of cacti”, where cactus plants account for almost half of the world, so that it has an important position in the history of Mexico, and is even regarded as a god or a sacred tree to ward off evil spirits. . Until now, Mexico’s flag, national emblem and currency have proudly standing cacti. There are also cacti planted everywhere in Mexico City, some of which are 15 meters high and have hundreds of branches, just like a towering tree; the largest cactus is two or three meters in diameter and weighs one ton. Although cacti are cute, their flowers are gorgeous and can reach up to 60 cm in diameter.
  The reason why cacti can spread from the Americas to all over the world, researchers believe that humans are an important medium for its long-distance transmission. After Columbus discovered the New World, missionaries and colonists began to transport cactus plants around the world. In addition, animals that feed on cactus fruits are also one of the ways for cactus to spread.

Super fecundity “cause trouble”

  From the 18th to the 19th century, the British army wore the famous red uniform. The reason why red was chosen was mainly because it was the cheapest and easiest color to obtain under the printing and dyeing technology at that time, and black gunpowder was mostly used in the war between the two armies. Can distinguish between enemy and me very well.
  So, how did the red dye come about? It has been found that there is a small insect called cochineal, which contains a lot of carmine acid, which can be processed to produce a safe and non-toxic natural dye, that is, carmine. This pigment is still widely used in food, cosmetics, pharmaceuticals and other industries, but before the rise of chemically synthesized pigments in the 19th century, cochineal red pigment was mainly used to dye cloth.
  In order to obtain a mighty red uniform, the British army needed a large amount of carmine as a dye. However, the cochineal breeding industry at that time was monopolized by Spain for a long time, and the export value of carmine in Mexico (then Spanish colony) was second only to gold and silver. In Oaxaca alone, the average annual production of carmine between 1758 and 1780 reached 1 million pounds. In order to maintain a monopoly, the Spaniards do everything possible to keep their breeding secrets. Because of the high import prices, Britain had to plan to introduce cochineal farming to its colony, Australia.
  Cochineal is mainly parasitic in cactus, since we want to develop aquaculture, we must first introduce its host cactus. According to records, the first two species of cacti from America entered Australia in 1788. Unexpectedly, the climate there is hot and dry, and although it is surrounded by sea, there are many arid or semi-arid areas. The cochineal insects that were introduced could not adapt and died quickly, but the cactus was like a duck to water, spreading like wildfire in this environment without natural enemies.
  By 1900, cacti covered an area of ​​more than 40,000 square kilometers in Australia; 20 years later, the land had expanded by nearly six times—nearly the size of the United Kingdom. Farming and grazing have become completely inaccessible here due to the flood of cacti, and farmers have lost large tracts of land.
  The decades-long war between humans and cacti kicked off. Initially, the government issued a bounty for anyone who could figure out a way to eradicate the cactus, but few responded. The thorn-covered cactus kept stabbing people and animals, and septicemia occurred frequently, and the government began to panic, and meetings to manage the cactus would be held every once in a while.
  In desperation, the government invested a lot of money, hired special personnel, digging roots, slashing, or even spraying poison, but it has never found a “one-shot enemy” method to prevent the continuous erosion of cacti. And in the process of fighting against the cactus, people also discovered the invincible reproductive ability of this plant. Like the “unkillable little strong”, it still spread to Queensland and other areas under various pressures.
Natural enemy “cactus moth” discovered

  Scientists have carried out extensive research on the cactus, looking for its dead spot. It was not until 1925 that people discovered the natural enemy of the cactus in Argentina, the cactus moth, which is a kind of insect of the Homopteran moth family, which is native to South America and feeds on cacti. The discovery was a lifesaver for the Australian government, which spent a lot of money on the introduction of cactus moths.

  The cactus moth really lived up to expectations. Scientists put its eggs in a cactus, and the larvae would invade the cactus after hatching. When they were full, the cactus completely lost its vitality. Just like that, 100 people traveled in seven vans around Queensland and New South Wales, handing out paper tubes containing cactus moth eggs to landowners. Between 1926 and 1931, more than 2 billion eggs were distributed. It took seven years for the cactus moth to gradually kill the unscrupulously spreading cactus, and it was not until the last cactus concentration in Queensland was destroyed that 70 million acres of land slowly returned to agricultural land and pasture.
  It is thought that it was once tortured by cacti. In order to commemorate the contribution made by the cactus moth, people in Australia also built a memorial for it, which was selected as a cultural heritage of Queensland.
  It’s not just Australia that is suffering from the cactus invasion. Kenya is also suffering and is now looking for a more effective cure around the world.
  In 1940, when British colonists entered Kenya, they also brought in cacti that were not originally there and used them as a kind of fence. Cactus is very “qualified” for this role. Not only is it green, but its spines can successfully prevent the invasion of wild animals. But in recent years, the plant has grown out of control in Kenya. In Kenya’s Laikipia County, these creatures have occupied more than 500 square kilometers, so much so that locals call them “devil cacti,” according to the International Agricultural Biotechnology Center. What is even more frightening is that most of Kenya’s natural pastures are being occupied by them, and hungry elephants have to approach human settlements, and conflicts between the two sides continue to occur. And when the elephant swallows the cactus, it will be stabbed by the thorns, which will enter the intestine and cause damage. The cactus invasion has also had a knock-on effect, and it is affecting the entire ecosystem in the region, leaving locals feeling overwhelmed.
  Why not follow the example of Australia’s biological control experience? Kenya fears that a mass release of the moth will upset another balance. They are looking for new ways to use the plant rationally, such as producing biogas.
There are also endangered species in “Little Plants”

  Not all cacti can become invasive species, and some species are endangered because of their small growing area or extremely slow growth rate, coupled with excessive human mining.

  The reason why cacti can spread from the Americas to all over the world, researchers believe that humans are an important medium for its long-distance transmission. After Columbus discovered the New World, missionaries and colonists began to transport cactus plants around the world. In addition, animals that feed on cactus fruits are also one of the ways for cactus to spread.

  A research report published in the journal “Nature Plants” shows that researchers from the University of Exeter in the United Kingdom conducted data analysis on 1,478 cacti species, according to their distribution area, number trend, habitat and ecological environment characteristics, preservation. Factors such as condition, use, and trade led to the conclusion that nearly 30 percent of cactus species are endangered.
  The report mentioned that some cacti, which seem to have tenacious vitality, also have strict requirements on the growing environment. Once the climate or soil is destroyed, it is difficult to continue to survive. Among the many destructive factors, human activities are the main cause of plant endangerment, such as uncontrolled logging and utilization, illegal trade and so on. Indirect causes are more complex, such as atmospheric, water and soil pollution, invasive alien species, global warming, impaired ecosystem functions, and the degradation of animal groups on which plants depend. These will directly reduce the number of plant groups or indirectly interfere with the normal maintenance and renewal of plant groups. When the number of a specific plant group is reduced to a certain number, it will enter the state of endangered, critically endangered, extinct in the wild or extinct. At present, in the 2019 “Convention on International Trade in Endangered Species of Wild Fauna and Flora” published by my country’s Scientific Committee on Endangered Species, a total of 39 species in the cactus family have been included in Appendix I, all of which are first-class endangered species, such as flower cages, tortoise shell peony, etc. .
  If you think that the extinction of plants has little effect on the natural world, it is a big mistake. The so-called “one hair moves the whole body” means that organisms in nature are never isolated. They are all in a huge and complex food chain. The disappearance of one of them will cause the function of a specific ecosystem to be disordered, declined or even collapsed.

  Cacti are a key component of the ecological environment in arid regions, and are vital to the survival of many animals, directly affecting the biodiversity of the ecosystems they host. For example, cacti provide food and water for animals such as deer, wood mice, and rabbits, and these species help spread cactus seeds; cactus flowers provide nectar for hummingbirds, and insects such as bees pollinate them. It can be seen that if the cactus is missing, it will cause disorders of multiple species.
  It may take millions of years for a species to be born, but it may only take a few short years for human activity to cause its permanent disappearance. Although many plants have completely disappeared from the sight of human beings, it is not too late to start the protection action. Minimizing the disturbance to plants as much as possible is the best action for human beings.