The purpose of our study is to consider the possibilities of using different approaches to recognize the significance of the territory for the biodiversity conservation. The Ichalkovsky nature reserve (zakaznik) with an area of 1,442 hectares in the Nizhny Novgorod region was selected for analysis as a botanical and geological object unique for the Russian Plain. The criterion of various rare wildlife species records was used as a leading approach. Analysis of published materials and field research in 2020 allowed us to identify in the studied territory the habitat of 88 wildlife species listed in the Red Data Books of Russia and the Nizhny Novgorod Region. They are very different concerning their taxonomy and biology. This criterion use shows the extremely high conservation value of the Ichalkovsky reserve. The territory under consideration is characterized by high biological diversity and a high degree of biota remained, as well as its weak human disturbance. It is shown that, in accordance with the approaches of international nature conservation programs, the Ichalkovsky reserve has the status of a territory of special nature conservation significance within the Emerald Network of Russia, as well as an Important Bird Area. This territory is the core of the environmental framework of European Russia and meets the criteria for identifying several categories of high conservation value forests. The proposed ways have shown high efficiency. Ichalkovsky reserve is very important to conserve the biodiversity, including at the international level. This natural area should have legal protection adequate to its nature conservation value. Such protection can be provided by the status of a cluster of a national park.