A species that has a large impact on the balance of an ecosystem even if its population is small is called a keystone species. It is a wedge-shaped stone at the top of a stone arch, and if this keystone is removed, the whole arch will collapse. It is an important species that stabilizes the entire ecosystem of the region.
https://nougyoudoboku.com/conservation-target-species/
Without wolves, moose would stay in one place and eat all the plants. With wolves, moose move around cautiously, so a moderate amount of plants remains. Beavers, known as ecosystem engineers, build dams to increase aquatic life, African elephants, known as giant gardeners of the forest, cut down overgrown acacia trees to allow light to penetrate the forest, and parrotfish eat the large algae that cover the corals.
https://logmi.jp/knowledge_culture/culture/187311
Other keystone species include termites and sea otters. Sea otters eat sea urchins. If the number of sea urchins increases, the seaweed will be eaten up, so sea otters are necessary. The termites are not the species that nest in the pillars of Japanese houses, but the ones that live underground in the savannah. They have a high nitrogen fixing ability and may provide more than 50% of the nitrogen required by the local trees.
https://gendai.media/articles/-/73936?page=3
In addition, the Saguaro cactus has roots that can grow up to 30 meters long, stores water, and can survive droughts, providing food and resting places for many species. It is long-lived, and can store up to 1,000 to 2,000 kg of water. It certainly seems to support many lives. In addition, the hay piles made by the high-altitude pikas not only provide food for themselves, but also help other species survive the harsh winter.
https://lifeontheplanetladakh.com/ja/blog-jp/large-eared-pikas-ladakh-jp
Vultures, lions, bees, and salmon also seem to fit this category. They seem to be just as important as we imagined. We looked into a variety of species that caught our eye, and we can see that keystone species, which maintain the balance of the ecosystem with a small population, are important. They are said to be indispensable pieces, and it feels like they are really intertwined like a puzzle. The Earth’s ecosystem is amazing, as it is complex yet balanced.