A chronosequence study of vegetation dynamics on vine and caper terraces of Pantelleria Island (Sicily)

The vegetation of fallow fields of different age in the terraced agricultural landscape of Pantelleria Island (Sicily) was analysed via vegetation relevés. Five age classes in N-facing as well as in S-facing slopes of both vine and caper fallows were differentiated. The main questions were to determine the sequence of plant communities in time and to test some environmental factors for their influence on the course and the speed of succession. The results show that undisturbed abandoned terraces are subject to rapid renaturation: 50 to 80 years old fallows are now covered by dense maquis communities. Both N- and S-facing slopes seem to converge to a Quercus ilex woodland as the climax community. However, the succession pathways differ in terms of communities included as well as in their temporal occurrence. Woody species invasion into fallows is slower on South-facing than on North-facing slopes. Ordination with DCA revealed that age of a fallow, exposition and the presence of safe sites are the most influential environmental factors. Safe sites were provided by former crop plants traditionally planted in artificial depressions, and are more quickly colonized by maquis saplings than areas not classified as safe sites. The predictable sequence of plant communities in the course of succession can be “frozen” by a few species able to form almost monospecific stands. These are Cistus sp. pl., known to show enhanced germination from seed bank after fire, or clonal species such as Rubus ulmifolius, Andropogon distachyon and Hyparrhenia hirta.