Effects of Disturbance on Understory Vegetation across Slovenian Forest Ecosystems

Kutnar Kutnar,Nagel Nagel,Kermavnar Kermavnar

doi:10.3390/f10111048

Kutnar Kutnar, Nagel Nagel + Show 1 more

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https://doi.org/10.3390/f10111048

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Journal: Forests	Publication Date: Nov 19, 2019
Citations: 29	License type: CC BY 4.0

Affiliation: University of Ljubljana, Slovenian Forestry Institute

Abstract

The herbaceous understory represents a key component of forest biodiversity across temperate forests of Europe. Here, we quantified changes in the diversity and composition of the forest understory layer in representative Slovenian forest ecosystems between 2004/05 and 2014/15. In total, 60 plots were placed across 10 different managed forest types, ranging from lowland deciduous and mid-altitude mesic mixed forests to mountain conifer forests. This network is part of an international network of sites launched within the ICP Forests Programme aimed to assess the condition of forests in Europe. To examine how disturbance influenced understory dynamics, we estimated the disturbance impacts considering both natural and/or anthropogenic disturbances that cause significant damage to trees and to ground-surface layers, including ground-vegetation layers and upper-soil layers. Species richness across 10 sites (gamma diversity) significantly decreased from 272 to 243 species during the study period, while mean species richness per site did not significantly change. The mean value of site level Shannon diversity indices and evenness significantly increased. The cover of most common plant species increased during the monitoring period. The mean value of disturbance estimates per site increased from 0.8% in 2004/05 (ranging from 0% to 2.5%) to 16.3% in 2014/15 (ranging from 5.0% to 38.8%), which corresponded to a reduction in total vegetation cover, including tree-layer cover. More disturbed sites showed larger temporal changes in species composition compared to less disturbed sites, suggesting that forest disturbances caused understory compositional shifts during the study period. Rather than observing an increase in plant diversity due to disturbance, our results suggest a short-term decrease in species number, likely driven by replacement of more specialized species with common species.

Highlights

Biodiversity in forestlands has become one of the major concerns of forestry in the EuropeanUnion, as well as globally [1]
The mean value of disturbance estimates per site increased from 0.8% in 2004/05 to 16.3%
In forest ecosystems studied within the ICP Forests monitoring programme in Slovenia, a high level of plant diversity was documented at the beginning of monitoring period [30,31,32]

Summary

Introduction

Biodiversity in forestlands has become one of the major concerns of forestry in the EuropeanUnion, as well as globally [1]. As conservation of biodiversity has become one of the important goals of managing forests in recent decades [2], variables and indicators related to biodiversity need to be monitored in forests, during the current period of rapid global change. Most of the plant diversity in temperate forest ecosystems is found in the understory herb layer. This diverse flora represents a wide variety of growth forms and functional groups, which collectively have an important influence on a variety of forest processes, including nutrient cycling and competitive interactions with tree regeneration [3]. The herb layer serves as an important source of food and habitat for wildlife and other forms of biodiversity [4].

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