The Mediterranean flora of Israel consists of about 1000 species, 10% of which are geophytes, mostly growing in open habitats. Anemone coronaria L, for example, is a beautiful geophyte, forming densely flowering fields that attract many visitors to open landscapes. Grazing may affect plant reproduction, survival and consequently population dynamics, but geophytes have underground regeneration buds and are considered to be grazing resistant. To date, only a few experimental studies have examined the mechanism of the impact of grazing on plant reproduction and population dynamics. In the present study we investigated the effect of cattle grazing on plant reproductive capacity and population densityof A. coronaria in northern Israel. Ten pairs of experimental plots were established, and one of each pair was fenced against grazing. Monitoring continued for five years. Two weeks of continuous cow grazing reduced the herbaceous biomass by 75% and the grass height by 90%, and increased solar radiation at ground level by 40%. Cows avoided eating A. coronaria flowers but damaged mature plants by trampling. We found that the numbers of flowers and fruits per plant, as well as fruit-set were not affected by grazing, but the number of dispersal units per plant decreased from 0.8 to 0.4. Five years of grazing exclusion reduced the density of flowering plants from 13 to 6 plants/m2. and that of seedlings from 1.5 to 0.6 individuals/m2. The results indicate that dense annual herbaceous vegetation interferes with A.coronaria, mainly by limiting germination sites and through competition for light. The fact that the average height of A.coronaria flowers was 26% greater in the absence of grazing implies that light is scarce for the geophyte when grasses are abundant. Grazing lowers competition from the herbaceous sward, and enhances seed germination and seedling establishment, plant growth and reproduction. In conclusion, grazing seems to be essential for the development and maintenance of large Anemone populations.
Racheli Schwartz-Tzachor, Ramat Hanadiv project, the Society for the Protection of Nature in Isreal.
Avi Perevolotsky,Department of Natural Resources ARO-the Volcani Center, Bet Dagan,Israel.
Rafi Yonatan, Department of Natural Resources ARO-the Volcani Center, Bet Dagan,Israel.
Gidi Ne'eman, Department of Biology,Faculty of Science and Science Education ,University of Haifa - Oranim ,Haifa ,Israel.