But today, wild boar has become a national protected animal, and hunting is prohibited without permission. With the continuous achievements of ecological construction in various places, the number of wild boar in many areas has gradually recovered, even to the point of flooding. For example, a rural wild boar flooded in Yixian County, Hebei Province, and a large number of excellent varieties were eaten up overnight. Even in many abandoned paddy fields in Guizhou, after being arched by wild boar, rice seedlings could even be watered.
Parts of China? Wild boar crossed the line? The scene after that
Looking around the world, there are more areas where wild boar is rampant, such as the United States, Italy, New Zealand, Australia and so on. Wild boar injury? The situation is even more serious, and Germany actually released it? Kill a 30 euro? Measures, also did not control the number of wild boar.
Many people may be confused when they see this. Take China as an example, many animals have been protected, and even the time node of comprehensive protection is much earlier than that of wild boar. But why is the number of recovery far less than that of wild boar?
For example, since 1977 completely banned hunting, the number of Siberian tigers is still around 30, and the increase is slow. In fact, this is related to many factors, but in general, it shows a law: the more organisms at the bottom of the food chain, the easier it is to restore the population, especially the super-reproductive species such as wild boar.
boar
In high school biology, we learned such a concept, called? Ecosystem balance? Generally speaking, in a certain period of time, organisms in the ecosystem, organisms and the environment, through some interaction, reach a coordinated and stable state. This is a dynamic balance, which means it can be broken.
However, in the state that most forests are generally short of large carnivores, the number of wild boar has soared, which undoubtedly exceeds the bearing capacity of the environment, that is, breaking the balance of the ecosystem will naturally bring various hazards. Today, we will take wild boar as the starting point to talk about the ecological impact of too many herbivores.
The feeding habits of wild boar make the animals in the habitat? Feeling stressed? Wild boar is an invasive species to North America. Due to the lack of natural enemies, the wild boar population introduced to North America grew rapidly and soon reached the point of flooding, which made local farmers very uncomfortable. According to the latest research estimates, the number of wild boar in the United States has tripled since the 1980s, and its distribution range has expanded from the initial 18 states to 35 states today, and it is also showing a rapid expansion trend in Canada.
In addition, one of the most common concerns about the spread of wild boar is the impact on agriculture and animal husbandry, that is, economic losses. 2/kloc-at the beginning of the 20th century, wild boars brought economic losses of 65,438.05 billion dollars to the United States every year, but now with the rapid increase of the number of wild boars, they have brought economic losses of one million dollars to the United States every year.
Changes of distribution range of wild boar in the United States in the past 37 years
The proliferation of wild boar is often associated with cash crops, but with the deepening of research, people find that the impact of the surge in the number of wild boar is increasing, and it will even cause serious harm to the ecology.
2019 June 14 A research paper in the magazine Ecology and Evolution has attracted people's attention. Lashley, Michael? Colvin and others found that too many wild boars would pose a serious threat to biodiversity. The researchers used tracking cameras and other technologies to monitor 36 forest patches in the United States with a size of 4-4,000 hectares, and found that the biodiversity of forest patches infested by wild boar was generally less. Finally, through more detailed data, the researchers determined that there were about 26% more bird communities and mammal species in forest areas without wild boar, indicating that there were wild boars. Crowd out? Went out.
Wild boar is not a predator with low biodiversity in areas with wild boar. Why does it have such a strong impact on other species? At first, people were confused. After detailed research, it is found that the original problems still exist. Eat? Above all, wild boar can not prey on other large adult mammals, but it can cause great survival pressure on some smaller animals such as lizards, frogs and invertebrates.
Wild boar is an omnivore. Although its food is 90% composed of various plants, seeds, fruits, roots and so on, it will eat anything that can be eaten, including but not limited to eggs, fungi, insects, shellfish and so on.
Wild boar arches turtle eggs.
According to a paper in the 99th issue of the Journal of Ecology, in North Island, South Carolina, every breeding season, turtles climb the beach to lay eggs, and then bury the eggs in the sand for incubation. This is the law of nature and the key to turtle reproduction.
However, in 2005, it was first discovered that wild boar plundered turtles' eggs on the island. The general process is that the wild boar eats like crazy after the tortoise is born and gone? Gluttony field? Wild boar is good at digging up soil, but it is not easy for wild boar to dig up eggs and eat them on the soft beach.
Under the influence of wild boar eating eggs, the reproduction rate of turtles in the North Island of South Carolina has been greatly reduced, and even appeared in some years? Zero? This phenomenon is a fatal blow to the development of turtle population.
The diet of wild boar is really too miscellaneous. It will eat the eggs of many young mammals, underage individuals, most birds and amphibians, and even most small animals such as lizards and snails, which are the direct food sources of wild boar. Therefore, in the environment where wild boars live in large numbers, the survival pressure of other animals is great, and the reproduction rate is reduced, which eventually leads to the decrease of species diversity.
The habits of wild boar can change the environment, and the influence of wild boar on ecology is not only manifested in? Eat? As we all know, wild boar has a habit of rubbing soil or tree trunks with their bodies, which is their way of preventing parasites and scratching. On the surface, this is their own business and will not affect other animals or ecosystems, but it is not.
In the early years, large carnivores such as South China tigers and leopards lived in the Qinling Mountains, so the number of many herbivores was controlled. Later, tigers and leopards disappeared in large numbers, and human hunting just replaced their niche. The number of large herbivores has been in a downturn.
tiger
With the enhancement of people's awareness of animal and ecological protection and the crackdown on poaching by the state, the ecology in Qinling area has gradually recovered in recent years, and the number of many wild animals has increased significantly. In 2008, Chengdu Business Daily reported that the number of Qinling antelopes increased sharply, with more than 150 injured in recent ten years, resulting in more than 20 deaths.
Takin is a hoofed animal larger than wild boar, and its weight can reach more than 300 kilograms. Adult individuals have almost no natural enemies except tigers.
takin
Like wild boar, does takin prefer to take horns or bodies? Hey? Trunk, in their perennial? Daley? At present, many big trees are seriously damaged, and there are not a few cases of dying and cutting. In some areas of the Qinling Mountains, we can even see pieces of fallen wood, all of which are wild boar and takin? Masterpiece? .
Under the action of this kind of behavior, the most direct influence is to change the local vegetation distribution, so that the number of big trees in the forest decreases and the number of fallen trees increases, which is usually called environmental reconstruction.
Wild boar (me) and takin? Daley? tree trunk
There is also an extremely precious wild animal living in the Qinling Mountains, and that is the national treasure giant panda. Although the giant panda eats bamboo and won't compete with other herbivores, its favorite habitat is a mixed forest with more trees, and it doesn't like forests with more fallen trees. The existence of a large number of wild boar and takin will undoubtedly reduce the number of big trees in the forest, increase the number of fallen trees and directly reduce the living space of giant pandas.
In addition, like many animals, giant pandas also like to make odor marks on tree trunks, especially in estrus, and the transmission and communication of odor is particularly important. But what about wild boar, takin and so on? Daley? , directly label the smell of giant pandas? Shit? I don't need to tell you the consequences. Everyone knows.
It is difficult for giant pandas to mate in the wild, and the communication between females is blocked, which undoubtedly makes this situation worse, and finally greatly reduces the reproductive rate of wild giant pandas.
panda
What is the indirect effect of wild boar on species diversity? Pull one hair and move the whole body? As a part of the ecosystem, wild boar will affect the whole system in every aspect of daily life. All the above points are its direct impact on the ecological environment or biodiversity, but the impact of wild boar is far more than that. Even doing nothing can seriously affect other animals.
On the Channel Islands in California, USA, because the ecosystem on the island is relatively isolated, is it? External force? Before that, it remained relatively stable, even before the wild boar was just introduced 150 years, most wild animals? Peace and security? .
Island gray fox
There is a native fox on the island who once lived happily, but since the mid-1990s, things have changed. Local people began to use pesticides, pesticides and other means to control pests and animal injuries. Because pesticides will remain on animal carcasses, which is not good for vultures who eat carrion. As a result, the number of vultures has dropped sharply.
Just as the disappearance of butch and leopard has brought unprecedented development opportunities to herbivores, the disappearance of vultures has made its rival golden eagle develop rapidly.
The vulture is eating carrion.
Golden eagles are different from vultures. Their main food source is hunting, that is, they like to eat creatures. Therefore, when the number of golden eagles increases, local foxes will face extinction. Due to the predation of the golden eagle, the fox on the island was once extinct.
Some people may say, what does this have to do with wild boar? In fact, the golden eagle population can grow rapidly because there are a large number of wild boar living on the island, and the young wild boar with easy meat has become the main reason for the development of golden eagle. Food support? .
vulture
Why is the fox more seriously damaged by the golden eagle than the wild boar? This should start with reproductive capacity. The fox living in the Channel Islands of California is a small island gray fox with low reproductive capacity. A child can have five cubs, but most of them are 2-3. It takes 65,438+00 months for young foxes to reach sexual maturity, while the average life span of wild island gray foxes is 4-6 years. It is conceivable that a fox can leave only a handful of offspring in his life.
However, the reproductive rate and survival rate of wild boar are very high, with one fetus of 4- 12, or even two births a year. Of course, there is another key point. The golden eagle can only prey on wild boar cubs and poses no threat to sub-adult and adult wild boars, while the adult gray fox on the island only has 1-3kg. Young animals and adult animals are prey of golden eagles, resulting in two species that are the same food of golden eagles, and the degree of damage is completely different.
After realizing this situation, people thought many plans to restore the species number of small animals such as foxes. Finally, people took measures to clear the local wild boar, restore the number of vultures and keep foxes wild? Three steps? In this way, it turns out that this scheme is really useful.
According to the report of 20 1 1, the number of foxes in Beihangdao Islands has reached 2110. According to 20 12 statistics, the number of vultures in California channel islands has exceeded 50, and wild boar has been completely removed from these islands, and there is no possibility of recovery.
Too many herbivores are a threat to the ecology. How can herbivores go too far? This is a question with no standard answer, which needs to be calculated according to different ecosystem capacities according to local conditions. For tigers, in the Indian subcontinent and parts of Southeast Asia, it is reasonable to have no more than five tigers in 70 square kilometers of forest, while in Central China and North China, a 70 square kilometer South China tiger is saturated, and more is excessive.
Of course, different species cannot use the same set of standards. Maybe only one South China tiger can be raised in 70 square kilometers of forest, but 200 sika deer, 150 wild boar, thousands of insects and ants can be raised, and so on. Generally speaking, it is enough not to overdo it and see if it will upset the balance of the ecosystem.
Due to the general lack of large predators in the forest, the number of herbivores is developing rapidly, and it is bound to exceed the number that the environment can accommodate in a certain period of time without restrictions. The rabbit in Australia is a good example.
There were no rabbits in Australia, but they entered with the colonists in the 1950s of 19. Rabbits entering Australia soon showed super strength? Destroy? Without the restraint of natural enemies, the number of rabbits has increased rapidly. By 1907, almost the whole Australian continent was covered with rabbits. By 1926, the number of rabbits in Australia totaled about tens of billions.
Australian hare
Australia is called? A country riding on the back of a sheep? Since ancient times, animal husbandry has occupied an important position in the national economic industry, and the proliferation of rabbits has had a great impact on animal husbandry. 10 rabbits eat as much as 1 sheep. /kloc-How much grass do 0/0 billion rabbits eat every day? Rabbits munch on grass instead of eating roots, resulting in the destruction of a large number of grasslands and desertification of the land.
Of course, the consequences of rabbit flooding not only affect the vegetation coverage, but also have an impact on Australia's pillar industries and do great harm to local ecological damage. Many herbivores died out under the pressure of rabbits.
Excessive herbivores not only threaten the ecology when they are still alive, but sometimes threaten the ecology after they die. Some experts from Mississippi State University and Florida University cooperated to study the ecological consequences of large-scale animal deaths, among which wild boar was the research object.
Simulated mass death
The general process is to deploy nearly 15 tons of wild boar carcasses in Oklahoma, and then observe and study, and find a normal number of microorganisms. Scavenger? It is impossible to consume such a large number of animal carcasses in a short time, leading to the breeding of local bacteria and mosquitoes. With the decomposition of the corpse, a large number of gases, liquefied residues, acidic liquids, etc. are produced and flow into the soil, which changes the microbial community and soil composition of the soil, thus indirectly affecting the vegetation.