“…We saw such higher levels of grazing impact in areas under traditional grazing regime in the Palestinian Authority, southern Lebanon, the northern Sinai (Egypt) and the Bedouin rangelands in the Arad region (Israel). Therefore, the published values of remaining plant biomass and taxa in controlled experiments (e.g., Gutman and Seligman, 1979;Gutman et al, 1990Gutman et al, , 1999Noy-Meir, 1990;Seligman et al, 1959) represent only moderate levels of grazing. While the role of spines and thorns in defense from large herbivores is clear (e.g., Cooper and Owen-Smith, 1986;Grubb, 1992;Janzen, 1986;Nobel, 1994;Rebollo et al, 2002;Young, 1987;Zohary, 1983), they may also serve physiological functions, such as protecting from heating by the sun, lowering photoinhibition and insulation from low temperatures (Gibson and Nobel, 1986;Nobel, 1994).…”