Environmental factors influencing herb layer productivity in Central European oak forests: insights from soil and biomass analyses and a phytometer experiment

Abstract

Habitat productivity and vegetation bio- mass are important factors affecting species diversity and ecosystem function, but factors determining productivity are still insufficiently known, especially in the forest herb layer. These factors are difficult to identify because different methods often yield differ- ent results. We sampled the herb layer biomass and assessed soil nutrients, moisture and light availability in 100 m 2 plots in Czech oak forests. Habitat productivity was estimated independently from nutri- ent content in the soil, herb layer biomass and using a bioassay experiment (growing phytometer plants of Raphanus sativus under standardised conditions in soil samples taken from forest plots). The generalised linear model for herb layer biomass showed it to increase with light, soil phosphorus and moisture availability, but only 10.7% of its variation was explained by these factors. The phytometer biomass increased mainly with soil pH and phosphorus availability; together with soil C/N ratio these factors explained 56.1% of the phytometer biomass variabil- ity. Combined evidence based on different approaches indicates that canopy shading and soil phosphorus tend to be the most important factors influencing the herb layer productivity of the studied oak forests.