Abstract:

Aims A particular set of species that have the potential to inhabit a local community but are locally absent is called dark diversity. Our aim was to investigate the impacts of plant characteristics and environmental factors on the dark diversity in a broadleaved Korean pine (Pinus koraiensis) forest.

Methods The study was conducted based on survey data of a 9-hm² broadleaved Korean pine forest in the Liangshui National Nature Reserve of Heilongjiang Province. We estimated the dark diversity probability of main species by using the Beals index. The correlations between the shade tolerance index, importance value and dark diversity probability were evaluated, and the effects of life form and shade tolerance on dark diversity probability were analyzed at the individual level. The correlations between community completeness and environmental factors, and community completeness and species diversity were investigated at the plot level.

Important findings The results showed that: (1) Average dark diversity probability for these species in this plot was 77.79%. For arbors, Juglans mandshurica had the highest dark diversity probability of 97.21%; however, for shrubs, the dark diversity probability of Viburnum opulus subsp. calvescens and Rhamnus davuricawere the highest, at 98.01%. (2) The dark diversity probability was negatively correlated with the importance value. However, the shade tolerance index was positively correlated with the importance value. (3) There was no significant difference in the dark diversity probability between arbors and shrubs, but the dark diversity probability of shade-intolerant species was significantly higher than that of shade-tolerant species. (4) Slope and convexity were both significantly positively correlated with community completeness. Soil organic matter, soil available potassium, soil bulk density, mass moisture content, soil pH, soil available nitrogen, and soil total nitrogen were not significantly related to community completeness; however, soil available phosphorus, soil total phosphorus and volumetric moisture content were all significantly negatively correlated with community completeness. The correlations between the species diversity indices and community completeness were significantly positive. In short, the dark diversity probability of shade-intolerant species and rare species in the broadleaved Korean pine forest was relatively high. Slope, convexity, soil available phosphorus, soil total phosphorus and volumetric moisture content were the main environmental factors that significantly influenced community completeness. The higher the community completeness was, the higher the species diversity of the community.

Key words: dark diversity, community completeness, species diversity, shade tolerance, life form, environmental factor