Combined effects of climatic gradient and domestic livestock grazing on reptile community structure in a heterogeneous agroecosystem.
Grazing plays an important role in shaping ecological communities in human-related ecosystems. Although myriad studies have explored the joint effect of grazing and climate on plant communities, this interactive effect has rarely been studied in animals. We hypothesized that the effect of grazing on the reptile community varies along a climatic gradient in relation to the effect of grazing on habitat characteristics, and that grazing differentially affects reptiles of different biogeographic regions. We tested our hypotheses by collecting data on environmental characteristics and by trapping reptiles in four heterogeneous landscapes experiencing differing grazing intensities and distributed along a sharp climatic gradient. We found that while reptile diversity increased with grazing intensity at the mesic end of the gradient, it decreased with grazing intensity at the arid end. Moreover, the proportion of reptile species of differing biogeographic origins varied with the interactive effect of climate and grazing. The representation of species originating in arid biogeographic zones was highest at the arid end of the climatic gradient, and representation increased with grazing intensity within this area. Regardless of the climatic context, increased grazing pressure results in a reduction in vegetation cover and thus in changes in habitat characteristics. By reducing vegetation cover, grazing increased habitat heterogeneity in the dense mesic sites and decreased habitat heterogeneity in the arid sites. Thus, our results suggest that the same direction of habitat alteration caused by grazing may have opposite effects on biodiversity and community composition in different climatic contexts.
Spatial Ecology Lab, Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, 8410501, Beer-Sheva, Israel. rottemguy@gmail.com.|Behavioral Ecology Lab, Department of Life Sciences, Ben-Gurion University of the Negev, 8410501, Beer-Sheva, Israel. rottemguy@gmail.com.
Guy
G
Rotem
Spatial Ecology Lab, Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, 8410501, Beer-Sheva, Israel.
Yoni
Y
Gavish
The National Natural History Collections, The Hebrew University of Jerusalem, 91904, Jerusalem, Israel.
Boaz
B
Shacham
Spatial Ecology Lab, Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, 8410501, Beer-Sheva, Israel.|Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, 8499000, Beer-Sheva, Israel.
Itamar
I
Giladi
Behavioral Ecology Lab, Department of Life Sciences, Ben-Gurion University of the Negev, 8410501, Beer-Sheva, Israel.
Amos
A
Bouskila
Spatial Ecology Lab, Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, 8410501, Beer-Sheva, Israel.
Yaron
Y
Ziv
D000383:Agriculture; D000821:Animal Feed; D000818:Animals; D044822:Biodiversity; D002980:Climate; D004032:Diet; D017753:Ecosystem; D060434:Herbivory; D006801:Humans; D058751:Livestock; D010944:Plants; D011157:Population Dynamics; D012104:Reptiles; D014867:Water
D014867:Water
Arid; Biogeography; Ecotone; Fisher’s alpha; Habitat heterogeneity; Herpetofauna; Mediterranean