野生华山参生境调查与分析

为研究野生华山参的生境特征，采用野外实地调查的方法，对秦岭北坡中段至东段野生华山参的物候特征、群落特征、土壤性质进行调查分析。结果显示：（1）华山参多生于郁闭度在30%~45%之间的林下或林缘；所处的坡度多在15°~25°；土层厚10~20 cm，地表枯落物厚度3~5 cm。（2）华山参多生长于中低海拔山区，以盐肤木、锐齿槲栎、黄栌、枫杨等乔木建群；按生活习性划分，华山参生境内有木本植物16科28属36种，草本植物12科22属35种。（3）适于华山参生长的土壤多为森林棕壤，土壤pH的变异系数较小，仅为1.54%，呈中性；土壤中营养元素主要是植物凋落物经过分解后的产物。野生华山参种群在秦岭山区分布不连续，多数种群延坡面呈带状或片状分布。生境内水热分布较均匀，相对稳定，乔灌草发育较为完善。华山参种群多位于保护区内，植被保存良好，生境较为完整，但野生种群基本由成年植株组成，更新苗稀少，可能是有性生殖产生的种子没有得到有效传播和萌发，居群年龄结构不合理，属于衰退型居群，推测华山参自然更新困难是其致濒的主要原因。

Physochlaina infundibularis: Habitat Investigation and Analysis

To study the habitat characteristics of wild Physochlaina infundibularis, we made field survey and analysis on its phenological characteristics, community characteristics and soil properties in the middle to eastern section on the northern slope of Qinling Mountains. The following results are obtained. (1) P. infundibularis plants are mostly growing in or around woods with canopy closure ranging from 30% to 45%, at the slope ranging from 15° to 25°, soil layer thickness of 10-20 cm, and surface litter thickness of 3-5 cm. (2) P. infundibularis plants are mostly growing in mid-low altitude mountainous areas, forming a flora with Rhus chinensis, Quercus aliena, Cotinus coggygria, Pterocarya stenoptera and other trees; divided by living habits, there are 36 species in 28 genera of 16 families of woody plants, and 35 species in 22 genera of 12 families of herbaceous plants in the habitat of P. infundibularis. (3) The soil suitable for the growth of P. infundibularis is mostly forest brown soil, and the variation coefficient of soil pH is only 1.54%, which is neutral; the nutrients in the soil are mainly the products of the decomposition of plant litter. The wild P. infundibularis plants are distributed discontinuously in Qinling Mountains, and most of them are distributed in strips or sheets along the slope. In the habitat of wild P. infundibularis, the distribution of water and heat is relatively uniform and stable, and the development of trees, shrubs and grasses is relatively complete. Most populations of P. infundibularis are located in protected areas, with well-preserved vegetation and relatively complete habitats, but such wild plants are basically composed of adult plants, with few new seedlings. Maybe, because the seeds produced by sexual reproduction are not effectively disseminated and germinated, the populations are in improper age structure, which are declining. We speculate that the difficulty of natural regeneration of P. infundibularis is the main reason for its endangerment.