Abstract: Study of the distribution of species diversity is essential for biodiversity conservation. To understand fern species composition and their diversity distribution characteristics in the headwaters of the rivers in northern China, we investigated ferns in Hunhe River Source Nature Reserve in Liaoning Province and analyzed the characteristics of fern species diversity and distribution under different topographic conditions. The results showed that: (1) There were 17 fern species in the Hunhe River Source Nature Reserve, belonging to 13 genera of 8 families, and the dominant families were Dryopteridaceae and Athyridaceae. (2) Hippochaete hyemale, Athyrium multidentatum, Onoclea sensibilis var. interrupta, Lunathyrium pycnosorum, Matteuccia struthiopteris, Dryopteris crassirhizoma, and Neoathyrium crenulato serrulatum were common and representative species in the fern community of the Hunhe River Source region, with Hippochaete hyemale and Athyrium multidentatum as the dominant species. (3) Species diversity was significantly affected by elevation and slope direction. Margalef index was significantly different between the elevation 700-800 m and 500-600 m (P<0.05), and Margalef index and Shannon index were significantly different between north slope and south slope (P<0.05). (4) With increasing elevation, species diversity presented unimodal pattern distribution, and peaked in the mid-elevation. From north slope, east slope, south slope, then to west slope, species diversity showed a distribution pattern of the first falling and then rising, with the highest in the north slope and the lowest in the south slope. The species diversity in flat slope was the lowest, which was not the suitable slope for ferns to live on. The species diversity in the middle slope was the highest, indicating it was a suitable slope position for ferns to survive. This study provides basic data for the diversity conservation and ecological restoration of ferns in Hunhe River Source Nature Reserve and other areas with similar conditions.

Key words: fern, Hunhe River Source Nature Reserve, species diversity, topographic factor, dominant species.