A strange phenomenon in Zimbabwe led to a surprising discovery: antelopes today use what humans left in the Iron Age - 1,800 years ago
Ancient civilizations have left behind impressive buildings throughout human history that have been preserved due to their sanctity, beauty or importance. Forts built in strategic locations and famous sites such as the pyramids leave their mark on the landscape to this day. However, remains do not always remain, at least not visibly. Sometimes all traces of the people who lived there before disappear from the environment, and it becomes a fertile ground for the prosperity of animals - precisely thanks to human activity.
An example of this is found in the savanna of central Zimbabwe, where researchers have noticed in a strange phenomenon: circular areas, the size of an Olympic pool, where the vegetation is different from everything around them. Inside the circle grows nutritious grass, and outside the circle grow tall trees and bushes that characterize the surrounding space. team the researchers who tested the phenomenon placed cameras in the field and found that two vegetarian species of antelopes (impala and kudu) graze and feed on the grass inside these grassy circles more than in the surrounding tree areas. According to the researchers, the open terrain gives the antelopes the ability to spot threatening predators from a greater distance, which provides an additional advantage of being there.
What is the relationship between the circles and the person
As part of the research, the researchers tried to understand how the circles were formed and reached their historical origins: fenced enclosures established by shepherds and African nomads during the Iron Age, 1,800 years ago. In the southern part of Africa the nickname "kraal" (kraal) in the Afrikaans language refers to a place in which humans protected themselves and their grazing herds. Cattle dung accumulated in the kraals for several years, before the herdsmen moved on to the next point, and thus in the places where people lived, the soil underwent a process of fertilization.
At many historical sites of human settlement, grass can now be found on which large herbivorous animals feed. This type of grass grows in soil that is rich in phosphorus and calcium derived from manure and organic waste. The presence of these components in the soil, after almost 2,000 years, encourages the growth of the grass that contributes to the prosperity of the antelopes.
Prosperity or outbreak
However, the human impact is not without environmental problems. Land management in the southern part of Africa does not take into account animal migration patterns and many open areas in Zimbabwe are fenced off. Therefore the question arises, is the prosperity of the antelopes in these areas good for nature? The study shows how human activity changes the dynamics in the habitat: more grasses and antelopes reduce the amount of trees and shrubs. From an ecological point of view, this can have negative consequences that are caused by humans. "Man is not part of the natural habitat," explains Dr. Tal Polak, director of wildlife conservation in the Ecology Division of the Nature and Parks Authority. "In any situation, our presence and influence causes damage," she explains. According to her, even when there are species that "are hired from human influence. For example, species close to humans or species that break out like jackals or wild boars", this is not a good thing - not for these animal species, and not for the environment. species מתפרצים They are species whose population has increased, under the influence of man, beyond the natural carrying capacity of the environment. In Haifa, you probably remember the storm of wild boars, who "profit" from the presence of man and then are a nuisance to him.
Polk explains that man became an environmental hazard when he stopped using the environment at the rate at which the environment is able to provide resources, and began to overuse its resources. For example, she suggests looking at the impact of man on bats in Israel. There are 33 species in Israel bats And almost all of them are found Endangered. Bats are particularly susceptible to poisoning due to their fast metabolic rate, high food consumption rate, low reproductive rate and long lifespan. Additional disturbances to bats are caused by construction and residences in areas that are expanding and increasing the light pollution. In the case of the bats, it is also possible to find a long-term effect attributed to the disinfectant D-D-T. This substance was used during the immigration period to exterminate parasites among the immigrants and to spray in agriculture. However, even decades after its use was stopped, in the 2000s it was still found among bats in the Hula Valley.
This study brings with it an important lesson, and the researchers propose to learn from the factors that influenced ecosystems in the past in order to preserve them even today - for example, with the help of using fertilizers to fertilize the vegetation in pasture areas. This method was known in the Land of Israel already thousands of years ago, and there are testimonies For the use of three pigeons for fertilization purposes as far back as the Hellenistic period, 2,400 years ago. Human influence allows some species to reproduce, but this does not necessarily contribute to them or the environment. "Human activity makes the habitat sub-optimal," Polk concludes.
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