Amur tiger (Panthera tigris altaica) and Amur leopard (P. pardus orientalis), the flagship species of the ecosystems, mainly prey on red deer (Cervus elaphus), sika deer (C. nippon), roe deer (Capreolus pygargus), and wild boar (Sus scrofa) in the national park region, while the ungulates rely on forest understory plants. All form the major parts of the grazing food chains in the temperate forest ecosystem of Northeast Asia. The main objective of this study is to comprehend the understory plant resource of the area, and establish baseline data through a vast investigation of the forest vegetation in the eastern part of the national park, in order to facilitate the estimation of the carrying capacity of the system in supporting the prey populations. In the growing seasons of 2015 and 2016, 141 sample locations associated with the established camera-trap platforms.were randomly selected The 496 transects were nested with the sampling locations, and 1948 sampling plots further nested with the transects. In this nested sampling system, understory biomass, plant group (tender twigs/leaves, grasses/sedges, forbs, and ferns) compositions were investigated, and nitrogen and carbon contents of plant groups were tested. We found that, (1) Forest canopy closure influences the light availability of the understory vegetation, and its productivity and plant group composition. The understory biomass at the open sites was 3 times of that under the closed canopies (94.91 g/m² vs. 30.15 g/m²，P<0.01). (2) At the open sites, understory biomass was the highest at riparian areas, At the gaps, tender twigs/leaves mainly dominated, while at forest edges, forbs did so, and along the riparian area, mainly sedges. (3) The understory tender twigs/leaves and forbs had the highest N contents, forbs had the lowest C contents and therefore the lowest C/N ratios. The forbs and the tender twigs/leaves should be the better forages for the ungulates. (4) The calorific values of all four understory plant groups were above 17kJ/g with the forbs the lowest. (5) Based on the data, high understory biomass (>40 g/m²) plots dominated by the tender twigs/leaves and forbs were about 16 % of the close canopy plots and 50 % of the open site plots, which could be the hot forage sites for browsers. With the study results, we suggest to maintain some open habitats, as the supplement highly quantity and quality forage patch for wild ungulate i.e. sika deer, to boost their populations for facilitating restoration of the tiger and leopard.

东北虎和东北豹主要捕食马鹿、梅花鹿、狍  及野猪等大中型有蹄类动物，而这些有蹄类的生存依赖森林灌草层的植食性食物资源，形成了东北亚温带森林生态系统完整的啃食食物链 (grazing food chain) 主体。本研究通过对建设中的东北虎豹国家公园东部地区有蹄类栖息地的灌草层植物进行本底调查，获得有蹄类动物的食物资源基线数据。2015年及2016年生长季，在东北虎豹国家公园东部，随机选择141个样地嵌套496条样线，1948个样方，对不同森林结构 (郁闭林及开阔生境，开阔生境包括林窗、林缘和河岸带) 的灌草层植物生物量、食物类别组成 (嫩枝叶、禾莎草、杂类草和蕨类) 及碳、氮含量进行调查分析。研究结果显示：灌草层生物量在开阔生境显著高于郁闭林下 (94.91 g/m² vs. 30.15 g/m²)，达到3.15倍。三种开阔生境下的灌草层食物资源类别组成差异显著，在林窗内以嫩枝叶优势，在林缘以杂类草占优势，在河岸带以蕨类占优势。灌草层中杂类草和嫩枝叶平均氮含量高，杂类草碳含量低、C/N低；四类植物热值均超17kJ/g，其中嫩枝叶最高。嫩枝叶、杂类草占优势的高生物量 (生物量大于40 g/m²) 斑块占郁闭林下的16 %、占开阔生境的50 %左右，可能是精食者 (browser) 的取食热点区域。建议在未来国家公园建设中，在合适的地段保留一定的开阔生境，为梅花鹿等食草动物补充高质量的灌草层食物资源斑块，促进有蹄类动物种群发展，并以此为基础恢复虎豹种群。