Do Ellenberg’s indicator values apply to the vascular plants colonizing decaying logs in mountain forests?

Abstract

We investigated the applicability of Ellenberg’s indicator values (EIVs) on coarse woody debris (CWD). Given that a small number of vascular plant species forms the pool of potential colonizers, we wanted to examine whether the properties of decaying logs and site characteristics can be predicted using EIVs. A comparison was made between the EIVs of the flora inhabiting mineral soil and plants colonizing 364 decaying logs of Picea abies and Fagus sylvatica in the Karkonosze Mts., southern Poland. We used correlation tests to assess the relationships between the mean and weighted EIVs and the decomposition stage of a decaying log, light conditions and moisture as well as the altitude at which the dead logs were lying. There were no significant differences in the mean EIVs between the species growing on mineral soil and CWD, except for the soil reaction, which was higher on the spruce logs. The plants colonizing decaying downed trees reflect the climatic conditions and altitude, i.e. elevation index, approximated heat load and vegetational gradient better than the edaphic conditions, i.e. the properties of dead wood such as its decomposition and moisture. We concluded that, in spite of the fact that in terms of biotopes fallen trees can be treated as synusia in forest communities, bioindication using the EIVs is not only possible but also predictable. Species that are present on CWD thus should be included in assessments of forest habitat conditions.