Effect of spatial and temporal patterns of stress and disturbance intensities in a sub-Mediterranean grassland

Abstract

The present study examined a sub-Mediterranean pastoral system in the central Apennines (Italy) with a long history of grazing, where winter cold stress is alternated with summer drought stress. The research goals were to ascertain whether different floristic structures correspond to different stress conditions (xeric and semimesic), and whether peculiar functional plant traits (such as avoidance and tolerance mechanisms) respond to stress/disturbance intensities, and understand how vegetation reacts to changeable livestock pressure (through floristic and plant trait variations). Cluster analysis indicated that separate communities develop under different stress intensities. Other analyses highlighted how avoidance strategies predominate within the pastoral system. Observations of grazed and ungrazed patches conducted in 10-m transects revealed spiny cushion formation in semimesic grassland, where a brief period of overgrazing occurs in late summer, causing variations in plant community structure. All these results confirm the importance of historical grazing and current land use, showing how small disturbances and stress variations cause ecosystem responses. Best practices for management were identified. In xeric conditions, it is advisable that the intensity of disturbance be lessened, while in semimesic grassland overgrazing should be forbidden during the dry period, because it could facilitate the development of spiny patches, and subsequent spread of Brachypodium rupestre.

Keywords:

• Avoidance/tolerance
• floristic changes
• functional plant traits
• grazing management
• stress and disturbance intensities
• sub-Mediterranean grasslands

Acknowledgements

The research was financed by Marche Region as part of the European Union project “Laboratory of environment and landscape – APE Apennine European Park.” We would like to thank the University of Camerino Calculation Centre for furnishing SPSS 13.0 software, the Marche Region agrochemical analysis and research laboratories for providing the soil analyses, and Dr. Sheila Beatty for the English revision of the article.