PhD defence: Lasse Gottlieb

Lasse Gottlieb defends his thesis:

Large herbivores in temperate woodlands 
- Effects on vegetation composition and dynamics

Supervisors:
Senior adviser, Rita M. Buttenschøn
Professor, Inger Kappel Schmidt

Assessment Committee:
Professor Jens-Christian Svenning, Aarhus University
Senior lecturer Annika Fenton, Swedish University of Agricltural Science
Professor Per Gundersen (Chair), Department of Geosciences and Natural Resource Management, University of Copenhagen

Summary:
Large herbivores are increasingly reintroduced to temperate European woodlands with the aim of restoring missing ecosystem processes and promoting biodiversity. This has increased the scientific and political awareness of the impacts, but the scientific evidences are generally lacking behind, with literature characterised by several assumptions and knowledge gaps. The overall objective of this PhD thesis was to investigate the impact of large herbivores on vegetation composition and dynamics in temperate woodland ecosystems, and to provide empirical evidence on topics where data and documentation are lacking or scarce. This includes the temporal dynamics and long-term effects on the vegetation community, the actual and realized impacts of European bison (Bison bonasus), and the indirect large herbivore-induced resource alterations for insect communities.
In paper 1, we use a uniquely obtained dataset to investigate the long-term effects of cattle grazing on the ground vegetation, while looking into complex, non-linear response patterns and the temporal stability of the cattle-induced impacts as well.
In paper 2, we provide some of the first empirical evidences for the impact of European bison on the ground vegetation in forest habitats.
In paper 3, we investigate the browsing impact of European bison on forest regeneration, their selectivity among different tree species, their bark stripping habits, and eventually evaluate bison’s ecological filtering effect.
In paper 4, we investigate the impact of year-round cattle grazing on abundance and richness of flowers of insect-pollinated forbs as well as floral nectar sugar production. This study gives the first empirical evidences concerning the effect of year-round cattle grazing on floral resource abundance and diversity.