Can Wapiti (<i>Cervus elaphus</i>) Browsing Stimulate the Chemical Defense of <i>Taxus cuspidata—</i>A Case of Northeast China Tiger and Leopard National Park

The interactions between animals and plants are the most critical processes in terrestrial ecosystems. Northeast China Tiger and Leopard National Park is one of China's first five national parks, where the recovery of the amur tiger (Panthera tigris altaica) and its prey populations is vital for biodiversity conservation. Wapiti (Cervus elaphus) is the class II national protected animal in China and one of the main prey of amur tiger. Taxus cuspidata is a Tertiary relict tree and the class I national protected plant and wapiti browsing its saplings is likely to increase its endangered status. Given that both species serve as key conservation priorities in the national park, there is an urgent need to address the ecological balance between them. From 2020 to 2024, we conducted camera traps, field investigation, and high performance liquid chromatography to study the interaction between them. We found that wapiti mainly browsed the saplings in 20-100 cm. When the height reaches 250 cm, it can avoid being browsed. After being browsed, saplings tend to abandon the growth of the main branches and focus on the recovery of lateral branches and ground diameters. The concentration of tannins doubles, while the concentration of terpenoids nearly triples and that of flavonoids almost doubles after browsed by wapiti. Wapiti did not browse the same saplings twice. In summary, although wapiti browsing inhibits the growth of saplings, the chemical defense also ensures that it is not browsed twice. The results not only provide a scientific basis for solving the cooperative conservation of wapiti and T. cuspidata but also promote the study of interaction and co-evolution between large herbivores and rare plants.