IALC Peace Fellowship Report August 2005

Gal Yaacobi 
Graduate Student 
Ben-Gurion University of the Negev, Israel

Causes and Predictions of Species Loss 
in a Fragmented Semiarid Landscape

The International Arid Lands Consortium Peace Fellowship Program enabled me to travel to the University of Arizona and work with Dr. Michael L. Rosenzweig. We analyzed a large data set, collected in our semiarid biodiversity research (supported by IALC) as a case study for answering a fundamental question in ecology: How to predict species loss due to fragmentation processes.

The biodiversity research takes place in the Southern Judea Lowland in Israel, a very fragmented semiarid environment. This area is characterized by a mixture of different-sized natural habitat patches, located between agricultural fields and human developments. Due to the climatic conditions and location of this area, where three biogeographic zones overlap (the Saharo-Arabian, Irano-Turranian and Mediterranean), it is exceptionally important for conservation of both species diversity and genetic variability. However, the area is at high risk owing to prospective developmental plans and further fragmentation. Furthermore, we know very little how ecological processes influence species diversity and community structure in this area.

In order to predict the species loss in the research area, we applied new quantitative methods and computer applications of species diversity estimators. This new analysis revealed fascinating results, linking observed patterns of species loss of different taxa to different mechanisms. Some groups such as ground beetles showed sensitivity to reduction in habitat area without any additive influences, while another group, perennial flowering plant showed reduction in species number due to fragmentation processes.

We emphasize that, regardless of the effect of fragmentation, a reduction in area immediately results in a reduction in species diversity. However, conservation biologists should test for whether any reduction is indeed a product of fragmentation or merely a result of the species-area curves. Our experiment is especially important because it suggest/produces a founded/established mechanism for the observed phenomenon of reduction in species number.

NOTE: A paper is in final preparation and an abstract has been published in the proceedings of an Israel Zoological Society conference held on 1 January 2006.