From its inception, the U.S. Department of the Interior has been charged with a conflicting mission. One set of statutes demands that the department must develop America's lands, that it get our trees, water, oil, and minerals out into the marketplace. Yet an opposing set of laws orders us to conserve these same resources, to preserve them for the long term and to consider the noncommodity values of our public landscape. That dichotomy, between rapid exploitation and long-term protection, demands what I see as the most significant policy departure of my tenure in office: the use of science-interdisciplinary science-as the primary basis for land management decisions. For more than a century, that has not been the case. Instead, we have managed this dichotomy by compartmentalizing the American landscape. Congress and my predecessors handled resource conflicts by drawing enclosures: "We'll create a national park here," they said, "and we'll put a wildlife refuge over there." Simple enough, as far as protection goes. And outside those protected areas, the message was equally simplistic: "Y'all come and get it. Have at it." The nature and the pace of the resource extraction was not at issue; if you could find it, it was yours.

From its inception, the U.S. Department of the Interior has been charged with a conflicting mission. One set of statutes demands that the department must develop America's lands, that it get our trees, water, oil, and minerals out into the marketplace. Yet an opposing set of laws orders us to conserve these same resources, to preserve them for the long term and to consider the noncommodity values of our public landscape. That dichotomy, between rapid exploitation and long-term protection, demands what I see as the most significant policy departure of my tenure in office: the use of science-interdisciplinary science-as the primary basis for land management decisions. For more than a century, that has not been the case. Instead, we have managed this dichotomy by compartmentalizing the American landscape. Congress and my predecessors handled resource conflicts by drawing enclosures: "We'll create a national park here," they said, "and we'll put a wildlife refuge over there." Simple enough, as far as protection goes. And outside those protected areas, the message was equally simplistic: "Y'all come and get it. Have at it." The nature and the pace of the resource extraction was not at issue; if you could find it, it was yours.

This is the first international volume in the Long Term Ecological Research Network series. The book summarizes the state of knowledge about biodiversity in drylands, and seek to identify questions and strategies for future research and to lay out guidelines for management of biodiversity in desert and semidesert regions. The continuing sensitivity of drylands to desertification, the fact that they occupy 40% of the world's terrestrial area, and the increasing human populations in these regions, make the understanding of their biodiversity and its changes over time of central importance. Drylands also provide a natural laboratory to address general questions about biodiversity, ecological succession, etc., because the relative spareness of the landscape allows one to isolate all the variables more effectively than can be done in biologically "richer" terrains. This book brings together leading workers, primarily from the U.S. and Israel, with some European scientists, to develop an integrative synthesis of perspectives on biodiversity in drylands, considering work from multiple regions and investigations focussing on multiple levels of ecological analysis. Each chapter was written by a small team of investigators from different institutions and having experience in different systems. Each chapter team combines at least two ecological perspectives, for instance, population and ecosystem, or species and landscape.

This research relates to the two-phase mosaic made by shrubs and intershrub patches as a simple form of landscape diversity, and aims to study its effect on ground-dwelling beetle diversity. I studied the effect of shrubs on beet;e diversity with emphasis on the difference between shrub patch and intershrub patch. This difference is termed "contrast." The study was carried out in two stations within Israel - (1) an arid, shrub-poor ecosystem (Avdat) and (2) a semi-arid shrub-rich ecosystem (Lehavim). Results of pitfall trapping showed that more beetles were found under shrub patches in the arid site, but in the semi-arid ecosystem beetles were more abundant in the open patches. In order to understand the drivers behind these opposite patterns, I performed field observations of beetle movement, by looking at dominant Adesmia (Tenebrionidae) species. Their behavior showed strong links to the refuge offered and shading effect of shrubs. Results of a transplant experiment support the findings that shrub structure determines beetle behavior. The effect of the shrub-open patch mosaic on beetles is an example for the importance of landscape diversity in determining species diversity.