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Browse more than 5,500 book chapters authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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The F'derik-Zouerate iron district: Mesoarchean and Paleoproterozoic iron formation of the Tiris Complex, Islamic Republic of Mauritania
High-grade hematitic iron ores (of HIF, containing 60-65 wt%Fe) have been mined in Mauritania since 1952 from Superior-type iron deposits of the F'derik-Zouerate district. Depletion of the high-grade ores in recent years has resulted in new exploration projects focused on lower-grade magnetite ores occurring in Algoma-type banded iron formation (of BIF, containing ca. 35 wt% Fe). Mauritania is t
Authors
Cliff D. Taylor, Carol A. Finn, Eric D. Anderson, Dwight Bradley, Mohamed Joud, Ahmed Taleb Mohamed, John D. Horton, Craig A. Johnson
Biocrusts in the context of global change
A wide range of studies show global environmental change will profoundly affect the structure, function, and dynamics of terrestrial ecosystems. The research synthesized here underscores that biocrust communities are also likely to respond significantly to global change drivers, with a large potential for modification to their abundance, composition, and function. We examine how elevated atmospher
Authors
Sasha C. Reed, Fernando T. Maestre, Raul Ochoa-Hueso, Cheryl Kuske, Anthony N. Darrouzet-Nardi, Brian Darby, Bob Sinsabaugh, Mel Oliver, Leo Sancho, Jayne Belnap
Biological soil crusts: An organizing principle in dryland ecosystems (aka: the role of biocrusts in arid land hydrology)
Biocrusts exert a strong influence on hydrological processes in drylands by modifying numerous soil properties that affect water retention and movement in soils. Yet, their role in these processes is not clearly understood due to the large number of factors that act simultaneously and can mask the biocrust effect. The influence of biocrusts on soil hydrology depends on biocrust intrinsic character
Authors
Sonia Chamizo, Jayne Belnap, David J Elridge, Oumarou M Issa
Carbon budgets of biological soil crusts at micro-, meso-, and global scales
The importance of biocrusts in the ecology of arid lands across all continents is widely recognized. In spite of this broad distribution, contributions of biocrusts to the global biogeochemical cycles have only recently been considered. While these studies opened a new view on the global role of biocrusts, they also clearly revealed the lack of data for many habitats and of overall standards for m
Authors
Leopoldo G Sancho, Jayne Belnap, Claudia Colesie, Jose Raggio, Bettina Weber
Controls on distribution patterns of biological soil crusts at micro- to global scales
Biocrusts are heterogeneously distributed in space. The drivers of their distribution patterns vary
depending on the spatial scale of observation. Globally, there are about 1337 cyanobacteria,
algae, bryophyte, and lichen species reported as components of biocrusts. At the broadest
biogeographical scales, the degree and age of isolation of land masses may dictate distribution of
these species and
Authors
Jayne Belnap, Otto L. Lange, Matthew A. Bowker, Burkhard Buedel, Christophe Sannier, Nicole Pietrasiak, David Eldridge, Victor Rivera Aguilar
How biological soil crusts became recognized as a functional unit: a selective history
It is surprising that despite the world-wide distribution and general importance of biological soil crusts (biocrusts), scientific recognition and functional analysis of these communities is a relatively young field of science. In this chapter, we sketch the historical lines that led to the recognition of biocrusts as a community with important ecosystem functions. The idea of biocrusts as a funct
Authors
Otto L. Lange, Jayne Belnap
Natural recovery of biological soil crusts after disturbance
Natural recovery of biological soil crusts (biocrusts) is influenced by a number of different parameters, such as climate, soil conditions, the severity of disturbance, and the timing of disturbance relative to the climatic conditions. In recent studies, it has been shown that recovery is often not linear, but a highly dynamic process directly influenced by non-linear external parameters as extrao
Authors
Bettina Weber, Matthew A. Bowker, Yuanming Zhang, Jayne Belnap
Patterns and controls on nitrogen cycling of biological soil crusts
Biocrusts play a significant role in the nitrogen [N ] cycle within arid and semi-arid ecosystems, as they contribute major N inputs via biological fixation and dust capture, harbor internal N transformation processes, and direct N losses via N dissolved, gaseous and erosional loss processes (Fig. 1). Because soil N availability in arid and semi-arid ecosystems is generally low and may limit net
Authors
Nichole N. Barger, Eli Zaady, Bettina Weber, Ferran Garcia-Pichel, Jayne Belnap
Synthesis on biological soil crust research
In this closing chapter, we summarize the advances in biocrust research made during the last 1.5 decades. In the first part of the chapter, we discuss how in some research fields, such as the microbial diversity of fungi, bacteria, and microfauna; the interaction between biocrusts and vascular plants; and in the rehabilitation of biocrusts; particularly large achievements have been made. In other
Authors
Bettina Weber, Jayne Belnap, Burkhard Buedel
Modeling flow, sediment transport and morphodynamics in rivers
Predicting the response of natural or man-made channels to imposed supplies of water and sediment is one of the difficult practical problems commonly addressed by fluvial geomorphologists. This problem typically arises in three situations. In the first situation, geomorphologists are attempting to understand why a channel or class of channels has a certain general form; in a sense, this is the cen
Authors
Jonathan M. Nelson, Richard R. McDonald, Yasuyuki Shimizu, Ichiro Kimura, Mohamed Nabi, Kazutake Asahi
Surficial geological tools in fluvial geomorphology: Chapter 2
Increasingly, environmental scientists are being asked to develop an understanding of how rivers and streams have been altered by environmental stresses, whether rivers are subject to physical or chemical hazards, how they can be restored, and how they will respond to future environmental change. These questions present substantive challenges to the discipline of fluvial geomorphology, especially
Authors
Robert B. Jacobson, James E. O'Connor, Takashi Oguchi
Vegetation as a tool in the interpretation of fluvial geomorphic processes and landforms
This chapter exemplifies that vegetation can be used as a tool for geomorphic interpretation in several major ways. It presents a general overview: through dendrogeomorphic analysis (tree rings) to estimate the timing of important geomorphic events including floods and mass wasting and to estimate rates of erosion and sedimentation; through the documentation and interpretation of species distribut
Authors
Cliff R. Hupp, S Dufour, G Bornette