The relationships between patch size and Sarcopoterium spinosum association properties at the Mediterranean fringe-Israel

Habitat loss and landscape fragmentation are considered factors that cause a significant decrease in biodiversity and changes in the community composition. The impact of fragmented natural patches of various sizes on plant species richness, plant composition, and soil properties were investigated in this study. The study area was located in a semiarid Mediterranean region (average annual rainfall 300 mm/winter) and dominated by Sarcopoterium spinosum L. (SP) association. The results indicated that: (a) SP dwarf-shrubs were absent from patches of less than one hectare; (b) SP and other perennial coverage increased with patch size; however (c) herbaceous plants dominated the patches (70-100%); (d) the annual grasses Stipa capensis Thunb. and Avena sterilis L. were the dominant species and their coverage was significantly higher in the small patches; (e) species richness increased with patch size; (f) the total number of species for all the patches was almost two times higher than in the adjacent nature reserve; (g) native weeds such as Chrysanthemum coronarium L. and Centaurea hyalolepis Boiss. abounded in the patch edges; (h) the similarity between the patches and the adjacent nature reserve increased with patch size, but was less than 35%; and (i) rock fragments were almost absent from the small patches where the soil was shallower than in the large patches. In conclusion, on the patch scale, it is important to conserve larger patches. However, on the landscape scale, it is recommended to conserve the various patch sizes because of their high biodiversity.