Measurement of ungulate palatability to and browsing pressure on the Japanese flora

The modern era has led to ungulates becoming dominant and altering natural ecosystems. They browse or graze unevenly on palatable plants, causing a change in the vegetation of unpalatable species. Ungulated palatability is a primary plant trait in plant community assembly. Browsing pressure at a site is the threshold palatability value between browsed and unbrowsed plants at the site, and it should be used for managing an ungulate population to conserve endangered and culturally important plants and maintaining the regeneration of forests with palatable trees. Thus, estimating palatability and browsing pressure are crucial techniques for ecosystem management. Herein, we compared four methods to estimate palatability based on a browsing scar survey and the palatability of 195 plant species from boreal to warm-temperate zones in Japan. Based on the palatability, a browsing pressure map for planning regional ecosystem management was depicted. The four methods assessed typically yielded similar results, although simple logistic regression caused outliers for extremely palatable and unpalatable plants. The species-to-species comparison matrix method, which is a method involving survey data restriction, accepts broad types, whereas the likelihood-distance method and Bayesian logistic regression methods necessitate a countable number of examined plants. The plants listed in the results can be used as indicator species to determine browsing pressure in field surveys. Thus, these methods for estimating palatability and browsing or grazing pressures will contribute to future progress in plant community studies and ungulate management.