Assessment of grazing effects on the Mediterranean shrub Phillyrea latifolia L. with developmental instability and fractal analysis

Developmental instability was used in this study and was expressed as translational and fluctuating asymmetries as well as fractal dimension in order to assess the effects of different levels of grazing pressure by goats on a dominant and palatable species of Mediterranean shrublands, i.e. Phillyrea latifolia L. Treatments included lightly, moderately and heavily grazed areas as well as an ungrazed area as a control. Measurements were carried out in thirty shrubs in each treatment. The fluctuating asymmetry analysis revealed higher asymmetry of leaves in the grazed treatments than in the control. The lower parts (below 1.5m height), reached by goats, also attained larger values of asymmetry in comparison to the upper parts (above 1.5m height) of the shrubs, not reached by goats. Moreover, fractal dimension of branches was lower in the grazed treatments in comparison to the ungrazed ones, as well as in the lower parts compared to the upper parts of the shrubs. However, the results of translational asymmetry analysis showed that grazed shrubs were developmentally more stable than the ungrazed ones. These results suggest that Phillyrea is very tolerant to grazing. It is concluded that developmental instability and fractal dimension are useful tools in  assessing the differential response of Mediterranean key species to grazing impact. In addition, evidence is provided of the manifestation of developmental instability as a result of environmental disturbance under the same genetic basis.