tion in Arid Settings of the Mojave Desert— Esque, and D. Bedford—Monitoring Ecosystem Quality Func Medica, M.L. Brooks, T.C. L.A. DeFalco, P.A. D.M. Miller, M.E. Miller, J. Belnap, R.H. Webb, Recoverability and Vulnerability of Desert Ecosystems Monitoring Ecosystem Quality and Function in Arid Settings of the Mojave Desert Scientific Investigations Report 2008-5064 Scientific Investigation Report 2008-5064 - U.S. Department of the Interior U.S. Geological Survey This page intentionally left blank Monitoring Ecosystem Quality and Function in Arid Settings of the Mojave Desert By Jayne Belnap, Robert H. Webb, Mark E. Miller, David M. Miller, Lesley A. DeFalco, Philip A. Medica, Matthew L. Brooks, Todd C. Esque, and Dave Bedford Recoverability and Vulnerability of Desert Ecosystems Scientific Investigations Report 2008-5064 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior DIRK KEMPTHORNE, Secretary U.S. Geological Survey Mark D. Myers, Director U.S. Geological Survey, Reston, Virginia: 2008 This report and any updates to it are available at: http://pubs.usgs.gov/sir/2008/5064 For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod Telephone: 1-888-ASK-USGS For more information on the USGS--the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov Telephone: 1-888-ASK-USGS Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. All photographs were taken by U.S. Geological Survey employees, unless otherwise noted. Suggested citation: Belnap, Jayne, Webb, R.H., Miller, D.M., Miller, M.E., DeFalco, L.A., Medica, P.A., Brooks, M.L., Esque, T.C., and Bed- ford, D.R., 2008, Monitoring ecosystem quality and function in arid settings of the Mojave Desert: U.S. Geological Survey Scientific Investigations Report 2008-5064, 119 p. Produced in the Western Region, Menlo Park, California Manuscript approved for publication, April 28, 2008. iii Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1 The Models .....................................................................................................................................................2 The Underpinnings of Ecosystem Sustainability: The Jenny-Chapin Model ..............................2 The Mojave Desert General Conceptual Dryland Model ...............................................................2 Connectivity of Components and Process ........................................................................................2 Regional Climate and Atmospheric Conditions ..............................................................................2 Climate ...........................................................................................................................................2 The Physical Template: Geology, Geomorphology, and Soils .................................................................6 Geology ...................................................................................................................................................6 Geomorphology .....................................................................................................................................7 Soils .........................................................................................................................................................7 Eolian Processes and Dustfall .................................................................................................12 Carbon and Nutrient Cycling ...................................................................................................13 Carbon ................................................................................................................................13 Nitrogen ..............................................................................................................................14 Phosphorus ........................................................................................................................14 Potassium ...........................................................................................................................14 Other Major Cations .........................................................................................................14 Micronutrients ...................................................................................................................15 Soil Biota .....................................................................................................................................15 Soil Surface Biota: Biological Soil Crusts .....................................................................15 Subsurface Soil Biota ......................................................................................................16 Vegetation .....................................................................................................................................................18 Annual Plants and Climatic Variability ............................................................................................19 Arthropods ....................................................................................................................................................20 Ants and Termites ...............................................................................................................................21 Beetles ..................................................................................................................................................22 Other Arthropods ................................................................................................................................22 Small Animals ...............................................................................................................................................22 Amphibians ..........................................................................................................................................23 Reptiles .................................................................................................................................................23 Small Mammals ...................................................................................................................................25 Natural and Anthropogenic Disturbances in the Mojave Desert ........................................................26 Natural Disturbances .........................................................................................................................26 Extreme Climatic Events ...........................................................................................................26 Fire........... .....................................................................................................................................26 Insect and Disease Outbreaks ................................................................................................28 Herbivory and Trampling by Wildlife .......................................................................................29 Anthropogenic Disturbance ..............................................................................................................29 Soil-Disturbing Activities ..........................................................................................................29 Soil Compaction ................................................................................................................29 iv Soil Stability, Nutrient Availability, and Vegetation .....................................................31 Effects of Specific Activities ....................................................................................................33 Livestock Grazing ..............................................................................................................33 Mining and Agriculture ....................................................................................................33 Military Activities ..............................................................................................................33 Off-road Vehicle Use and Roads ....................................................................................34 Hiking and Mountain Biking ............................................................................................36 Other Anthropogenic Disturbances .................................................................................................36 Urbanization ................................................................................................................................36 Introduction of Non-native Species .......................................................................................37 Atmospheric Changes ...............................................................................................................38 Air Quality