Richard V. Pouyat Deborah S. Page-Dumroese Toral Patel-Weynand Linda H. Geiser Editors Forest and Rangeland Soils of the United States Under Changing Conditions A Comprehensive Science Synthesis Forest and Rangeland Soils of the United States Under Changing Conditions Richard V. Pouyat • Deborah S. Page-Dumroese Toral Patel-Weynand • Linda H. Geiser Editors Forest and Rangeland Soils of the United States Under Changing Conditions A Comprehensive Science Synthesis Editors Richard V. Pouyat Deborah S. Page-Dumroese Northern Research Station Rocky Mountain Research Station USDA Forest Service USDA Forest Service Newark, DE, USA Moscow, ID, USA Toral Patel-Weynand Linda H. Geiser Washington Office Washington Office USDA Forest Service USDA Forest Service Washington, DC, USA Washington, DC, USA ISBN 978-3-030-45215-5 ISBN 978-3-030-45216-2 (eBook) https://doi.org/10.1007/978-3-030-45216-2 © The Editor(s) (if applicable) and The Author(s) 2020 . This book is an open access publication. 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The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Cover illustration: The soil around Lake Cleveland on the Sawtooth National Forest is formed in alluvium, colluvium, and residuum from a variety of sedimentary and metasedimentary rocks, dominantly quartzite. (Photo credit: USDA Forest Service) This Springer imprint is published by the registered company Springer Nature Switzerland AG. The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland English Equivalents When you know Multiply by To find Millimeters (mm) 0.0394 Inches Centimeters (cm) 0.394 Inches Meters (m) 3.28 Feet Kilometers (km) 0.621 Miles Hectares (ha) 2.47 Acres Square meters 10.76 Square feet (m2) Square kilometers 0.386 Square miles (km2) Kilograms (kg) 2.205 Pounds Megagrams (Mg) 1 Tons Petagrams (Pg) 1,102,311,311 Tons Teragrams (Tg) 1,102,311.31 Tons Degrees Celsius 1.8 °C + 32 Degrees Fahrenheit (°C) v Executive Summary Overview and Purpose Soils have life-giving and life-sustaining capabilities that directly or indirectly support all liv- ing organisms. Humanity’s well-being and health are tied directly to the health of soils. Worldwide, soil processes contribute to an abundant supply of water, food, and fiber while also tempering a warming climate. More than 40% of global terrestrial carbon (C) is stored in the soils of forests, grasslands, and shrublands (Jackson et al. 2017). Forest and rangeland soils of the United States make a disproportionately large contribution to such ecosystem services compared to their geographic extent. Although forests and rangelands occupy only about one- third of the land area in the United States, they supply 80% of the surface freshwater (Sedell et al. 2000) and sequester 75% of the total C to a depth of 30 m stored in the nation (Liu et al. 2013). Ecosystem alterations associated with land-use change and other pressures may impair the ability of soils to fulfill their foundational role. Today, a number of disturbances compound the vulnerability of forest and rangeland soils across the United States. Of greatest concern are various environmental changes, continued overgrazing, catastrophic wildfire, and invasive plant and animal species. Effects on soil health (soil functions mediated by living organisms) are expected to be more severe when two or more of these disturbances or stressors interact with each other. Changes in the climate are likely to magnify or accelerate all of these impacts on forest and rangeland soils. However, great uncertainty surrounds predictions of climate-induced impacts because overall effects will depend on the magnitude of temperature and precipitation changes and the frequency of extreme events. The purpose of this report is to synthesize leading-edge science and management informa- tion about forest and rangeland soils of the United States, offer ways to better understand changing conditions and their impacts on soils, and explore directions that positively affect the future of forest and rangeland soil health. Other assessments provide similar information for agricultural soils, so agricultural soils are not included in this report. This report outlines soil processes and identifies the research needed to manage forest and rangeland soils in the United States. Chapter 1 provides an overview of the state of forest and rangeland soils research in the nation, including multidecadal studies. Chapters 2, 3, 4 and 5 summarize various human- caused and natural impacts and their effects on soil C, hydrology, biogeochemistry, and bio- logical diversity. Chapters 6 and 7 consider the effects of changing conditions on forest soils in wetland and urban settings, respectively. Impacts include: • Climatic variability and change. Shifts in precipitation patterns, temperature increases and variability, and increases in atmospheric carbon dioxide (CO2) concentrations affect plant productivity, flooding, nutrient cycling, and biological populations. Changes in climate, coupled with an increase in the frequency and severity of extreme weather events, have had, and will continue to have, direct and cascading indirect effects on soil formation and associ- ated productivity rates, as well as physical, chemical, and biological processes. • Severe wildfires. Regardless of origin, wildfires are becoming larger, more frequent, more intense, and are lasting longer. Severe wildland fires impact the C and nitrogen (N) in soils, vii viii Executive Summary alter the environment for various communities, and can change the trajectory of forest com- position. Fire may also form hydrophobic (water repellent) layers in soil. These layers, coupled with loss of vegetation, can lead to accelerated erosion and nutrient leaching. • Invasive species, pests, and diseases. The introduction of a wide range of invasive species, from microbes, macrofauna, and macroflora, has important impacts on soil processes which are exacerbated by climatic changes. Furthermore, the ranges of some invasive insects and pathogens are expanding. Invasive species contribute to tree stress, and lead to decline and mortality, decline of biodiversity, and soil changes in organic matter composition and nutri- ents. Similar to landscapes after wildland fires, problematic species can create soil condi- tions that enhance flash flooding, soil erosion, and sediment loading. • Pollution. Air and water pollutants can dramatically affect soil characteristics and species composition. Acid deposition can cause nutrient leaching, while other pollutants such as some hydrocarbon compounds and various trace metals can cause other chemical changes in soils. Despite environmental policies designed to limit the release of pollutants, some continue to impact forest and range soils. Soil recovery from the impacts of these pollutants can take many decades. • Non-urban land uses can potentially have an impact on forest and range soils. Compaction is considered one of the most critical issues on forest and rangeland soils because it can severely alter the movement and storage of air, water, and nutrients in the soil. These changes can slow tree growth and negatively affect microbial populations. In addition, min- ing has disturbed millions of hectares of forest and grasslands in the United States. • Urban land use and change. Direct urban-induced effects that can impact soils include the introduction of built structures, landfills, stormwater facilities, impervious surfaces, and lawn management. Urban land use and change may also affect soils through indirect pro- cesses such as the urban heat island effect, emissions of various pollutants, and the spread of non-native species. Chapter 8 considers approaches to maintaining or restoring forest and rangeland soil health in the face of these varied impacts. Chapter 9 discusses mapping, monitoring, and data sharing as ways to leverage scientific and human resources to address soil health at scales from the landscape to the individual parcel (monitoring networks, data-sharing Web sites, and educa- tional soils-centered programs