Plant diversity and soil properties in pristine and managed stands from Bosnian mixed forests

Abstract

We compared pristine and managed beech–fir mixed forests in Bosnia to assess the impact of management on plant species diversity, vegetation structure and soil–vegetation interaction. Traditionally, management of Bosnian mixed forests has been by the opening of small gaps, similar to those occurring naturally. Species composition revealed three successional vegetation groups, two mainly in managed forests (regenerating and mature) and one mainly in pristine old growth forests. Managed sites showed a tendency to be more diverse in plant species than pristine sites, and were also more heterogeneous. Diversity was clearly explained by vegetation groups; mature managed stands showing the highest plant diversity and regenerating stands the lowest, both in terms of species richness and abundance distributions. Plant diversity decreased with canopy cover and increased with carbon concentration in the Ah horizon, being accurately modelled by both factors. Although topographical conditions were homogeneous among sites, vegetation was very sensitive to small changes in environmental variables at the local scale. Vegetation reflected a combination of past situations, represented by C in the Ah horizon, and current conditions, represented by canopy cover and the C : N ratio in the LF organic layers, suggesting both sensitivity to present-day environmental conditions as well as the imprint of past events.