The role of management on the rate of secondary succession in Mediterranean shrubland after fire

Abstract

Ephemeral grasslands follow fire in Mediterranean batha communities on phosphorus-deficient terra-rossa soils, but successional processes rapidly restore shrub dominance. In an experiment aimed at reducing the rate of successional change and extending the period of grassland dominance, phosphorus was applied to a shrub community dominated by Sarcopoterium spinosum. This was done once in 1988, immediately after a fire. Two years later, the regenerating shrubs were treated with herbicide. Subsequently, the vegetation in the treatments was monitored for 20 consecutive years. The vegetation was undisturbed during the winter/spring growing season but was grazed during the dry summer of each year by beef cattle, which were given ad libitum access to poultry litter to supplement the nitrogen deficiency of the dry herbaceous vegetation. In control plots, the shrubs returned to pre-fire dominance within 5 years. With phosphorus and herbicide, shrub dominance was delayed by the vigorous herbaceous vegetation for more than 20 years. The practical feasibility of this management option depends on the relation between costs and benefits. A preliminary economic analysis based on the long-term experiment and a case study allowed us to define the conditions under which control of successional shrub encroachment can be economically feasible.

Keywords:

• brush control
• Calicotome villosa
• economic analysis
• grazing season
• phosphorus
• Sarcopoterium spinosum

Acknowledgments

This research was funded by the Northern Israel R&D Unit, the Jewish National Fund, the Soil Conservation Division of the Israel Ministry of Agriculture and Rural Development and the International Arid Lands Consortium (IALC). Special thanks are due to Mrs. Havah Aharon for her aid in the preparation of the data for analysis and to Mr. Yehuda Yehuda for his help with the field work. Research was funded by a contribution from the Agricultural Research Organization, Bet Dagan, Israel, 131/2010.