The impact of grazing on plant fractal architecture and fitness of a mediterranean shrub (Anthyllis cytisoides L.)

1. We examined natural grazing by livestock (sheep and goats) on Albaida Anthyllis cytisoides L. with the aim of determining whether variation in the allometric relationships between plant parts provides a sensitive indicator of the impact of grazing.

2. The intra-individual variation in translatory symmetry with scale and increased complexity of fractal structures reflect environmental disturbance under heavy grazing pressure and lack of grazing.

3. Fitness consequences of grazing were also investigated. Grazing promotes growth and adult survival, and a drop in seed production as a consequence of consumption. In spite of that, total inclusive fitness (population rate of change) tends to increase with grazing.

4. Moderate grazing, while promoting growth, also enhances stability of vegetative structures. The favourable effect of moderate levels of herbivory on A. cytisoides is reflected in the homeostatic maintenance of its translatory symmetry and in the increased complexity of its fractal structures.