BIODEPTH: Biodiversity and ecological processes in terrestrial herbaceous ecosystems: experimental manipulations of plant communities

• Research unit: EU RFP
• Project number: 95.0521

Key words (English)

Agriculture; biodiversity; disturbance; ecgsystem processes; grassland; productivity; species richness; stability

Alternative project number (English)

EU project number: ENV4-CT95-0008

Research programs (English)

EU-programme: 4. Frame Research Programme - 3.1 Environment

Short description (English)

See abstract

Partners and International Organizations (English)

Coordinator: Imperial College of Science Technology (UK)

Abstract (English)

The BIODEPTH research network investigates the effects of grassland biodiversity on ecosystem structure and processes in a series of field experiments across Europe. At eight sites experimental grassland communities ranging from monocultures to the maximum species richness of the respective sites have been established. Measurements involving standardised protocols started in 1995 (Switzerland) and 1996 (remaining partners). The Swiss project entails additional treatments to test how diversity is influenced by disturbance (lifestock trampling), drought, herbivores and weed invasions.
In undisturbed plots aboveground biomass increased significantly with increasing species richness and functional-group diversity in all years (1995-1999). In 1999 we stopped weeding the plots, but even if weed biomass was included aboveground biomass increased with increasing plant-species richness. Hence our most diverse plots have maintained the highest forage yields.
As in previous years, in 1999 we observed that experimental trampling reduced aboveground biomass yields, relative to undisturbed plots. Also in the third year of the trampling treatment aboveground biomass yields were highest in most diverse communities. The same result was obtained when the different ecosystems were exposed to simulated drought, but in contrast to our expectations, diverse communities were not more resistant and they did not recover faster after the drought experiment than low diverse communities i.e. they were not more resilient. However, biotic disturbances such as experimental addition of a polyphagous herbivore species or of a plant hemiparasite with a wide host range caused increasing damage with decreasing diversity. Hence, loss of plant diversity resulted in reduced resistance against such disturbances. Species richness also was a key factor explaining the amount of weed invasion into disturbed (trampling, addition of a plant parasite) and control plots as species-poor grassland communities were particularly susceptible to weed invasion.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 95.0521