Pieter Roovers

Plant species variation across path ecotones in a variety of common vegetation types

The objective of this study was to evaluate the effects of prolonged recreational disturbance on vegetation structure. Therefore, plant species variation along trails was determined in some common vegetation types of Flanders (Belgium). The study sites included two forest types, one grassland and one heathland. Inventory was conducted in transects perpendicular to trail centre. Field data on frequency, percent cover and multiple habitat variables were collected in the path, transition and undisturbed zones of the respective transects. In order to determine plant response groups in relation to recreational disturbances, distribution of plant species across paths was linked with their respective life form and plant strategy. Generally, species diversity increased towards the trail centre. The intensity of soil compaction was highly correlated with species cover and composition. Since soil compaction is interrelated with other aspects of the biotic and abiotic environment, it is clear that trampling exerts multiple stress on vegetation.

May seed banks contribute to vegetation restoration on paths in temperate deciduous forest

Forest paths are characterised by a zonation in vegetation composition as a result of gradients in abiotical conditions and continued recreational impact. Little is known about how much seed bank composition is affected by recreation and the existing path structure. As it is difficult to assess the contribution of seed banks to vegetation restoration, this study imparts relevant knowledge to restore vegetation on paths which are closed for recreational use. We surveyed seed bank and field layer vegetation composition in transects across path ecotones in deciduous forest. Analysis concentrated on seed bank characteristics and similarities of the seed bank and field layer vegetation in terms of ecological and seed size groups. A total of 74 species and 9,815 seedlings germinated out of the seed bank samples. The total seed density does not differ between path zones, but significant differences exist in the depth distribution and composition of the seed bank throughout transects. There is a large discrepancy between the composition of the seed bank and the vegetation. Small seeded species of disturbed environments dominate in each path zone. Typical forest species dominate in the vegetation while their contribution to the seed bank is low. Only with reference to the proportion of species of forest edges and clearings, the seed bank and vegetation do not differ significantly. Similarity between the seed bank on the path centre and the vegetation in the respective path zones decreases towards the undisturbed forest vegetation. Some competitive species like Urtica dioica and Lythrum salicaria are excessively represented in the seed bank and efficiently may obstruct further visitor use. However, these early successional species may not contribute to the conservation values of forests. Therefore management should carefully consider alternative amendments (e.g. soil scarification and seeding) to stimulate vegetation restoration.