Methods in Stream Ecology

By F. Richard Hauer

Methods in Stream Ecology, Second Edition, provides a complete series of field and laboratory protocols in stream ecology that are ideal for teaching or conducting research.

This updated edition reflects recent advances in the technology associated with ecological assessment of streams, including remote sensing. In addition, the relationship between stream flow and alluviation has been added, and a new chapter on riparian zones is also included.

The book features exercises in each chapter; detailed instructions, illustrations, formulae, and data sheets for in-field research for students; and taxanomic keys to common stream invertebrates and algae.

With a student-friendly price, this book is key for all students and researchers in stream and freshwater ecology, freshwater biology, marine ecology, and river ecology. This text is also supportive as a supplementary text for courses in watershed ecology/science, hydrology, fluvial geomorphology, and landscape ecology.

• Exercises in each chapter
• Detailed instructions, illustrations, formulae, and data sheets for in-field research for students
• Taxanomic keys to common stream invertebrates and algae
• Link from Chapter 22: FISH COMMUNITY COMPOSITION to an interactive program for assessing and modeling fish numbers

• Language: English
• Publisher: Academic Press
• Release date: Apr 27, 2011
• ISBN: 9780080547435

Book preview

Table of Contents

Cover image

Title page

Copyright

Contributors

Preface

SECTION A: PHYSICAL PROCESSES

CHAPTER 1: Landscapes and Riverscapes

CHAPTER 2: Valley Segments, Stream Reaches, and Channel Units

CHAPTER 3: Discharge Measurements and Streamflow Analysis

CHAPTER 4: Dynamics of Flow

CHAPTER 5: Temperature, Light, and Oxygen

CHAPTER 6: Hyporheic Zones

SECTION B: MATERIAL TRANSPORT, UPTAKE, AND STORAGE

CHAPTER 7: Fluvial Geomorphic Processes

CHAPTER 8: Solute Dynamics

CHAPTER 9: Phosphorus Limitation, Uptake, and Turnover in Benthic Stream Algae

CHAPTER 10: Nitrogen Limitation and Uptake

CHAPTER 11: Dissolved Organic Matter

CHAPTER 12: Transport and Storage of FPOM

CHAPTER 13: CPOM Transport, Retention, and Measurement

SECTION C: STREAM BIOTA

CHAPTER 14: Heterotrophic Bacteria

CHAPTER 15: Fungi: Biomass, Production, and Sporulation of Aquatic Hyphomycetes

CHAPTER 16: Benthic Stream Algae: Distribution and Structure

APPENDIX 16.1: Cleaning and Mounting of Diatoms (modified from Van Der Werff 1955)

APPENDIX 16.2: Making Semipermanent Mounts of Soft Algae

APPENDIX 16.3: Most Common Lotic Algal Genera

APPENDIX 16.3: LEGENDS: Figures of Benthic Algal Genera (All scale bars = 10μm unless labeled otherwise)

APPENDIX 16.4: Detailed Taxonomic References for the Identification of Benthic Stream Algae

CHAPTER 17: Biomass and Pigments of Benthic Algae

CHAPTER 18: Macrophytes and Bryophytes

APPENDIX 18.1: Field Key to Genera of Common North American Stream Bryophytes

CHAPTER 19: Meiofauna

CHAPTER 20: Macroinvertebrates

Appendix 20.1

CHAPTER 21: Macroinvertebrate Dispersal

CHAPTER 22: Role of Fish Assemblages in Stream Communities

APPENDIX 22.1: Key to Common Freshwater Fish Families Found in Wadeable Streams of the U. S. (modified after Eddy 1957; color drawings by J. Tomelleri)

APPENDIX 22.2: Regional Freshwater Fish Guides by Continent and Country

SECTION D: COMMUNITY INTERACTIONS

CHAPTER 23: Primary Producer-Consumer Interactionsce

CHAPTER 24: Predator-Prey Interactions

CHAPTER 25: Trophic Relationships of Macroinvertebrates

APPENDIX 25.1: A Simplified Key to the Functional Feeding Groups of Lotic Macroinvertebrates

CHAPTER 26: Trophic Relations of Stream Fishes

CHAPTER 27: Stream Food Webs

SECTION E: ECOSYSTEM PROCESSES

CHAPTER 28: Primary Productivity and Community Respiration

CHAPTER 29: Secondary Production of Macroinvertebrates

CHAPTER 30: Decomposition of Leaf Material

CHAPTER 31: Riparian Processes and Interactions

CHAPTER 32: Effects of Nutrient Enrichment on Periphyton

Appendix 32.1: Calculations for Determining Solute Injection Rate for Specific Stream Concentration

CHAPTER 33: Surface-Subsurface Interactions in Streams

SECTION F: ECOSYSTEM QUALITY

CHAPTER 34: Ecological Assessments with Benthic Algae

CHAPTER 35: Macroinvertebrates as Biotic Indicators of Environmental Quality

APPENDIX 35.1: Tolerance Values for Macroinvertebrates

CHAPTER 36: Establishing Cause-Effect Relationships in Multi-Stressor Environments

Index

Copyright

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Contributors

Numbers in the parentheses indicate the pages on which the authors’ contributions begin

DONALD J. BAIRD

(835) National Water Research Institute and Canadian Rivers Institute, Department of Biology, University of New Brunswick, Fredericton, NB, Canada E3B 6E1

DAVID J. BATES

(79) FSCI Biological Consultants, Halfmoon Bay, BC, Canada V0N 1Y1

COLDEN V. BAXTER

(119, 761) Department of Biological Sciences, Idaho State University, Pocatello, ID 83209

E.F. BENFIELD

(711) Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0406

ARTHUR C. BENKE

(691) Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487-0206

MELODY J. BERNOT

(213) Department of Biological Sciences, Murray State University, Murray, KY 42071

PETER A. BISSON

(23) Pacific Northwest Research Station, USDA Forest Service, Olympia, WA 98512-9193

THOMAS L. BOTT

(663) Stroud Water Research Center, Avondale, PA 19311

WILLIAM B. BOWDEN

(381) Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT 05405

JOHN M. BUFFINGTON

(23) Rocky Mountain Research Station, USDA Forest Service, Boise, ID 83702

JAMES L. CARTER

(805) United States Geological Survey, Menlo Park, CA 94025

CHELSEA L. CRENSHAW

(761) Department of Biology, University of New Mexico, Albuquerque, NM 87131

JOSEPH M. CULP

(835) National Water Research Institute and Canadian Rivers Institute, Department of Biology, University of New Brunswick, Fredericton, NB, Canada, E3B 6E1

KENNETH W. CUMMINS

(585) California Cooperative Fisheries Research Unit, Humboldt State University, Arcata, CA 95521

CLIFFORD N. DAHM

(119) Department of Biology, University of New Mexico, Albuquerque, NM 87131

JACK W. FEMINELLA

(537) Department of Biological Sciences, Auburn University, Auburn, AL 36849-5407

STUART. FINDLAY

(239) Institute of Ecosystem Studies, Millbrook, NY 12545

KENNETH. FORTINO

(637) Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402

FRANCES P. GELWICK

(611) Department of Wildlife and Fisheries Science, Texas A&M University, College Station, TX 77843-2258

JANICE M. GLIME

(381) Department of Biological Sciences, Michigan Technological University, Houghton, MI 49931

JAMES A. GORE

(51) Department of Environmental Science, Policy, and Geography, University of South Florida St. Petersburg, St. Petersburg, FL 33701

STANLEY V. GREGORY

(273) Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331

NANCY B. GRIMM

(761) School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501

JACK W. GRUBAUGH

(249) Department of Biology, University of Memphis, Memphis, TN 38152

VLADISLAV. GULIS

(311) Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487-0206

MORGAN J. HANNAFORD

(805) Department of Biology, Shasta College, Redding, CA 96049

F. RICHARD. HAUER

(103, 145, 435) Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT 59860-9659

ANNE E. HERSHEY

(637) Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402

WALTER R. HILL

(103) Illinois Natural History Survey, Champaign, IL 61820

ALEXANDER D. HURYN

(691) Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487-0206

JOHN J. HUTCHENS, Jr.

(249) Biology Department, Coastal Carolina University, Conway, SC 29528-6054

GINA D. LALIBERTE

(327) Wisconsin Department of Natural Resources, Madison, WI 53716

GARY A. LAMBERTI

(273, 357, 537) Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556-0369

PETER R. LEAVITT

(357) Department of Biology, University of Regina, Regina, SK, Canada S4S 0A2

HIRAM W. LI

(489) Oregon Cooperative Fish and Wildlife Research Unit, Oregon State University, Corvallis, OR 97331

JUDITH L. LI

(489) Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331

MARK S. LORANG

(145) Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT 59860-9659

REX L. LOWE

(327) Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403

WILLIAM J. MATTHEWS

(611) Department of Zoology, University of Oklahoma, Norman, OK 73019

RICHARD W. MERRITT

(585) Departments of Entomology and Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824

G. WAYNE. MINSHALL

(721) Stream Ecology Center, Department of Biological Sciences, Idaho State University, Pocatello, ID 83209-8007

DAVID R. MONTGOMERY

(23) Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195

PATRICK J. MULHOLLAND

(187) Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6036

MARILYN J. MYERS

(805) U.S. Fish and Wildlife Service, Albuquerque, NM 87111

ROBERT W. NEWBURY

(79) Canadian Rivers Institute, University of New Brunswick, Fredericton, NB, Canada E3B 5A3

MARGARET A. PALMER

(415) Chesapeake Biological Laboratory, Center for Environmental Science, University of Maryland, Solomons, MD 20688

BARBARA L. PECKARSKY

(561) Department of Zoology, University of Wisconsin, Madison, WI 53706

BRUCE J. PETERSON

(637) The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02543

CATHERINE M. PRINGLE

(537, 743) Institute of Ecology, University of Georgia, Athens, GA 30602

VINCENT H. RESH

(435, 805) Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720

TENNA. RIIS

(381) Department of Biological Sciences, University of Aarhus, Aarhus, Denmark

SCOTT L. ROLLINS

(785) Department of Zoology, Center for Water Sciences, Michigan State University, East Lansing, MI 48824-1115

EMMA J. ROSI-MARSHALL

(213) Departments of Biology and Natural Science, Loyola University Chicago, Chicago, IL 60626

AMANDA. RUGENSKI

(721) Stream Ecology Center, Department of Biological Sciences, Idaho State University, Pocatello, ID 83209-8007

SIMON D. RUNDLE

(415) Marine Biology and Ecology Research Centre, Department of Biological Sciences, University of Plymouth, Plymouth PL4 8AA, UK

LEONARD A. SMOCK

(465) Department of Biology, Virginia Commonwealth University, Richmond, VA 23284-2012

JACK A. STANFORD

(3) Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT 59860-9659

ALAN D. STEINMAN

(187, 357) Annis Water Resources Institute, Grand Valley State University, Muskegon, MI 49441

R. JAN. STEVENSON

(785) Department of Zoology, Center for Water Sciences, Michigan State University, East Lansing, MI 48824-1115

DAVID L. STRAYER

(415) Institute of Ecosystem Studies, Millbrook, NY 12545

KELLER F. SUBERKROPP

(311) Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487-0206

JENNIFER L. TANK

(213) Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556-0369

FRANK J. TRISKA

(743) Water Resources Division, United States Geological Survey, Menlo Park, CA 94025

AMBER J. ULSETH

(637) Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853

H. MAURICE. VALETT

(119, 169) Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0406

J. BRUCE. WALLACE

(249) Institute of Ecology, University of Georgia, Athens, GA 30602-2603

AMELIA K. WARD

(293) Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487-0206

JACKSON R. WEBSTER

(169) Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0406

WILLIAM W. WOESSNER

(119) Department of Geology, University of Montana, Missoula, MT 59812

Preface

When the first edition of Methods in Stream Ecology was published in 1996, we hoped that it would prove useful to practicing stream ecologists, and perhaps as a supplementary textbook for aquatic ecology courses. However, we and our contributing authors have been delighted that the book has been accepted worldwide as the basic text in stream ecology. The first edition served well for ten years as a reference for both instruction and research. However, as in any dynamic research area, the book was in need of modernization to keep pace with important methodological developments. Unlike the first edition, which stressed exercises that could generally be completed within a few hours or an afternoon of intensive field work, the second edition provides both classroom-style exercises and research-level methods appropriate for the most rigorous investigations.

As we pointed out in the first edition, perhaps no other area of aquatic ecology requires a more interdisciplinary approach than stream ecology. Geology, geomorphology, fluid mechanics, hydrology, biogeochemistry, nutrient dynamics, microbiology, botany, invertebrate zoology, fish biology, food web analysis, bioproduction, and biomonitoring are but a few of the disciplines from which stream ecology draws. The science of stream ecology continues to advance at a remarkably rapid rate, as evidenced by the virtual explosion of publications in stream ecological research during the past two decades. Along with the rapid increase in research activity, we have seen a commensurate increase in the teaching of stream ecology at the upper undergraduate and graduate levels at major colleges and universities. Likewise, scientists, government agencies, resource managers, and the general public have grown keenly aware of stream ecology as an integrative science that can help societies around the globe grapple with environmental degradation of their water resources. Indeed, streams and rivers are fundamental to the human existence, and many organizations and user groups have emerged globally to protect these unique habitats that are so vital to global biodiversity, complexity, and sustainability. We hope that this book will also be of value to these groups.

Stream ecology has experienced many areas of rapidly advancing research, methodologies, and coupled technologies. The serious student or researcher will find that all chapters have been substantially updated and several topics not covered in the first edition have been added with new chapters, notably fluvial geomorphology, nitrogen cycling, dissolved organic matter, fungi, bryophytes and macrophytes, algal biomonitoring, and ecotoxicology. The book continues to provide the most comprehensive and contemporary series of methods in stream ecology, which can be used for teaching or conducting research. We hope that the book will be valuable to both the stream ecology student and the most seasoned scientist. Resource managers employed in the private sector or by federal or state agencies should continue to find this book an indispensable reference for developing monitoring approaches or for evaluating the efficacy of their field and laboratory techniques.

This second edition covers important topics in stream ecology organized within six major sections: Physical Processes; Material Transport, Uptake, and Storage; Stream Biota; Community Interactions; Ecosystem Processes; and a new section on Ecosystem Quality. Six new chapters have been added to the book, which now contains 36 chapters written by leading experts, and all existing chapters have been substantially revised and updated. Each chapter consists of (1) an Introduction, (2) a General Design section, (3) a Specific Methods section, (4) Questions for the student or researcher, (5) a list of necessary Materials and Supplies, and (6) relevant References. The Introduction provides background information and a literature review necessary to understand the principles of the topic. The General Design presents the conceptual approach and principles of the methods. The Specific Methods generally begin with relatively simple goals, objectives, and techniques and increase in the level of difficulty and sophistication; Basic Methods are suitable for the classroom, whereas Advanced Methods are applicable to high-end research projects. Each method is explained in step-by-step instructions for conducting either field or laboratory investigations. The methods presented are of research quality, and while it is not our intention to produce an exhaustive manual, we present rigorous methods that provide sound underpinnings for both instruction and research purposes. In each case, the methods presented are used frequently by the authors in their personal research or instruction. The Questions listed at the end of each chapter are formulated to encourage critical evaluation of the topic and the methods that were used to address a particular stream ecology issue. The comprehensive list of Materials and Supplies itemizes equipment, apparatus, and consumables necessary to conduct each method and is generally organized by each specific method to allow simple checklists to be made.

If this book is being used for course instruction, we recommend that instructors carefully consider the chapters and methods that they wish to use and plan carefully to budget the necessary time for setup, sampling, and analysis to complete individual or group research projects. Generally, classes should begin with Basic Methods and then delve more deeply into Advanced Methods as time and resources allow. We hope that all of the chapters will enrich the field of stream ecology as a rigorous scientific discipline. As before, we encourage the use of this second edition to assist in the formulation of exciting ecological questions and hypotheses and, to that end, the chapters present sound methods for discovery.

For course instruction, we recommend use of moderate-sized streams from 3 to 12 m wide that are easily waded. Smaller streams should be avoided by a large class, such as 10–20 students, because of the impacts incurred on a small environment. Large rivers are limiting to class instruction because of safety concerns and the inherent difficulties associated with sampling deep, flowing waters.

Reviewers and users of the first edition found this book to be particularly user friendly. Once again, this was one of our primary goals. As in the first edition, we have attempted to present a book with a logical flow of topics and a uniform chapter format and style, an approach that our authors embraced and implemented. We deeply thank our contributing authors and co-authors from the first edition, who once again gave of themselves and their time for the benefit of our science. We also welcome the authors of the added chapters and likewise thank them for their remarkable efforts. All of them tolerated with (mostly) good humor the fits and starts that characterized the production of this second edition. Chapter reviews were mostly conducted by authors of other related chapters, but several external reviewers also provided us with helpful reviews: Dominic Chaloner, Dean DeNicola, Paul Frost, Brian Reid, Dave Richardson, and Don Uzarski. We are grateful for their assistance.

The inspiration for this book arose from our own research and teaching. Numerous colleagues and students also encouraged the preparation of this second edition, often with suggestions of new chapters or methods that were not treated in the first edition. We are thankful for their input. Our graduate and undergraduate students continue to be a source of inspiration and encouragement to us even as this book has robbed from our time with them. Our own graduate and postdoctoral advisors (Jack, Art, Vince, and Stan) continue to support our endeavors even as they ruefully concede that we have become them. We gratefully acknowledge the assistance and financial support of our outstanding home institutions, the University of Montana and the University of Notre Dame. The highly professional staff at Academic Press/Elsevier was a pleasure to work with during this project. Finally, and most importantly, we thank our families for their continued love and support. Our wives, Brenda Hauer and Donna Lamberti, and our children, Andy and Bethany Hauer and Matthew and Sara Lamberti, have energized and inspired us throughout this endeavor and we will be forever grateful to them.

F. Richard Hauer, Gary A. Lamberti

SECTION A

PHYSICAL PROCESSES

Landscapes and Riverscapes

Jack A. Stanford

Flathead Lake Biological Station, University of Montana

I. INTRODUCTION

Streams, rivers, and groundwater flow pathways are the plumbing of the continents. Water coalesces and flows downhill in surface channels and subsurface pathways in response to precipitation patterns and the dynamic form of river basins (catchments). Uplift of mountain ranges, caused by continental drift and volcanism, is continually countered by erosion and deposition (sedimentation) mediated by the forces of wind and water. Catchment landscapes are formed by the long geologic and biological history of the region as well as recent events such as floods, fires, and human-caused environmental disturbances (e.g., deforestation, dams, pollution, exotic species).

The term landscape is used extensively, referring generally to the collective attributes of local geography. An expansive view of a stream or river and its catchment, including natural and cultural attributes and interactions, is the riverscape. For a stream ecologist, a riverscape view of a catchment (river) basin encompasses the entire stream network, including interconnection with groundwater flow pathways, embedded in its terrestrial setting and flowing from the highest elevation in the catchment to the ocean, with considerable animal and human modifications of flow paths likely along the way (Fausch et al. 2002). For example, the earth’s largest catchment, the Amazon River basin, occupies over half of the South American continent. Headwaters flow from small catchments containing glaciers and snowfields over 4300 m above sea level on the spine of the Andes Mountains to feed the major tributaries. The tributary rivers converge to form the mainstem Amazon, which flows from the base of the Andes across a virtually flat plate covered by equatorial tropical forest to the Atlantic Ocean. The altitude change is less than 200 m over the nearly 3000 km length of the mainstem river from the base of the Andes to the ocean. Because of the enormous transport power of the massive water volume of the Amazon River, some channels are >100 m deep. In other places along the river corridor the channel is >5km wide, relatively shallow, and filled by sediment deposition (alluviation). Flood waters spread out over huge and heavily vegetated floodplains that support a myriad of fishes and other animals (Day and Davies 1986).

The riverscape of the Amazon River, as among all rivers, was molded over time with the river cutting steep canyons through mountain ranges while building (alluviating) expansive floodplains where the slope of the river valley decreased. Rivers drain the continents; transport sediments, nutrients, and other materials from the highlands to the lowlands and oceans; and constantly modify the biophysical character of their catchment basins. These processes occur in direct relation to a particular catchment’s global position, climate, orography, and biotic character, coupled with spatial variations in bedrock and other geomorphic features of the riverscape.

Within a catchment basin, stream channels usually grow in size and complexity in a downstream direction (Figure 1.1). The smallest or first-order stream channels in the network often begin as outflows from snowfields or springs below porous substrata forming ridges dividing one catchment from another. Two first-order streams coalesce to form a second-order channel and so on to create the network (Strahler 1963). A very large river, like the Amazon, often has several large tributaries, and each of those river tributaries may be fed by several to many smaller streams (Figure 1.1). Thus, each large catchment basin has many subcatchments.

FIGURE 1.1 Idealized view of (A) the stream network showing the coalescence of headwater streams, which begin at snowfields or groundwater discharge portals, and the longitudinal distribution of floodplains and canyons (beads on a string) within a headwater to ocean river ecosystem and (B) the 3D structure of alluvial floodplains (beads), emphasizing dynamic longitudinal, lateral and vertical dimensions, and recruitment of wood debris. The groups of arrows in (A) indicate the expected strength of ground- and surfacewater exchange (vertical), channel and floodplain (lateral) interactions, and upstream to downstream or longitudinal (horizontal) connectivity in the context of (B). The floodplain landscape, contains a suite of structures (see Table 1.1) produced by the legacy of cut and All alluviation as influenced by position within the natural-cultural setting of the catchment. The parafluvial zone is the area of the bankfull channel that is to some extent annually scoured by flooding. The hyporheic zone is defined by penetration of river water into the alluvium and may mix with phreatic ground water from hillslope or other aquifers not directly recharged by the river. Alluvial aquifers usually have complex bed sediments with interstitial zones of preferential groundwater flow sometimes called paleochannels. Assemblages of biota may be segregated in all three spatial dimensions including riparos (streamside or riparian), benthos (channel bottom), hyporheos (interstitial within the stream bed-sediments) and phreatos (deep groundwater) in addition to fish and other organisms in the water column of the river

(from Stanford et al. 2005b).

Erosive power generally increases with stream size. Boulders, gravel, sand, and silt are transported from one reach of the stream network to the next in relation to discharge and valley geomorphometry (e.g., slope and relative resistance of substrata to erosion). Expansive deposition zones (floodplains) form between steep canyons, where downcutting predominates.

All rivers feature this basic theme of alternating cut and fill alluviation. Floodplains occur like beads on a string between gradient breaks or transitions in the altitudinal profile of the flow pathway (Leopold et al. 1964). Rivers of very old geologic age have exhausted much of their erosive power; mountains are rounded, valleys are broadly U-shaped, and river channels are single threads in the valley bottom with ancient, abandoned floodplains called terraces rising on either side. Whereas, in geologically young, recently uplifted catchments, stream power and associated erosive influence on valley form is great; mountains are steep-sided, valleys narrowly V-shaped, and the river spills out of many interconnected channels on alluvial floodplains in aggraded areas during flooding. Of course, no two rivers are exactly alike, but a general longitudinal (upstream to downstream) pattern of cut and fill alluviation usually exists (Figure 1.1A). Many small and usually erosive streams coalesce in the headwaters to form a main channel that grows in size and power with each primary tributary. The main channel alternately cuts through reaches constrained by bedrock canyons and spills water and sediments onto aggraded floodplain reaches where the river may be quite erosive (cutting) in one place and time and building sedimentary structures (filling) in another; thus, creating a suite of dynamic habitats for biota.

The riverscape at any point within the stream network is four-dimensional (Figure 1.1B). The river continuum or corridor from headwaters to ocean is the longitudinal (upstream to downstream) dimension. The second dimension is the transitional area from the river channel laterally into the terrestrial environment of the valley uplands (aquatic to terrestrial dimension). Except where rivers flow over impervious bedrock, some amount of porous alluvium is present within the channel owing to erosion at points upstream. Hence, water from the river may penetrate deeply into the substrata of the river bottom. Moreover, substrata of floodplains are composed of alluvial gravels and/or sands and silts, which allow lateral flow of river water. Hence, interstitial flow pathways constitute a vertical dimension in the river channel and on the floodplains. All of the physical dimensions change in size over time (the fourth dimension), as floods and droughts alter hydrology, sediment transport, and distribution of vegetation and other biota (Ward 1989, Stanford et al. 2005b).

Plants and animals are distributed in relation to biophysical gradients expressed by the four-dimensional nature of the stream network within catchment basins. For example, certain species of aquatic insects reside only in the cold, rocky environs of cascading headwater streams in the high mountains (rhithron environments), whereas other species are found only in the much warmer waters of the often sandy, turbid, and meandering reaches of the lowlands near the ocean (potamon environments) (Ward 1989). Thus, riverine biota have distinct preferences for specific environmental conditions that are optimal only at certain locations within longitudinal (upstream-downstream), lateral (aquatic-terrestrial), vertical (surface-ground water), and temporal (certain time) gradients that characterize lotic ecosystems (Figure 1.1). Andrewartha and Birch (1954) observed that the essence of ecology is understanding the distribution and abundance of biota. Because environmental conditions at any point in a stream are continuously influenced by conditions at points upstream, biophysical controls on distribution and abundance of riverine biota must be examined in the context of the stream and its landscape setting (Hynes 1975).

A key point is that the riverscape is not static. Rather, it is a dynamic, constantly shifting mosaic or catena of interconnected habitats (Table 1.1) that are created, modified, destroyed, and rebuilt by the interactive processes of cut and fill alluviation mediated by flooding and moderated by riparian vegetation. Trees fall into the channel as powerful flood flows erode floodplain benches covered by forests. The trees obstruct flow, causing deposition of sediments that subsequently allow seedling establishment. Dense growths of young trees catch more sediment, building new floodplain benches and gradually growing into riparian forests. Yet, flooding may knock them down again. Moreover, young riparian trees have to grow fast enough to keep their roots near or in the water table as flooding abates and the volume of the alluvial aquifer declines or they will die. Indeed, the changing volume of the alluvial aquifer and associated rise and fall of the water table coherent with flow in the channel is another important habitat forming process of alluvial floodplains. Overland flooding from the channel to the floodplain is obvious as bankfull flow is exceeded and water spills out of the channel network. Flooding from below ground is less intuitive, but in gravel-bed rivers the initiation of overbank flooding usually is preceded by filling of the alluvial aquifer to the extent that the surface is saturated and hyporheic water erupts into swales and abandoned channels, creating wetlands and spring brooks. Change from dry to wet condition associated with above and below ground flooding is called the flood pulse, and it allows aquatic and terrestrial biota to use the same space but at different times, thus vastly increasing biodiversity and bioproductivity of the riverscape (Junk 2005).

TABLE 1.1 Linked Structural (habitat) Elements of Floodplain River Landscapes. Channel and floodplain elements overlap spatially and interact temporally, but time frames differ among rivers. Perirheic habitats are lateral lakes and ponds fed by groundwater that occur on the floodplains of large tropical rivers as described by Mertes (1997). Not all of these elements will necessarily be present on every stream or river because the hydrogeomorphic setting varies even within the same river system.

(from Stanford et al. 2005b)

The Nyack Floodplain of the Middle Flathead River in Montana is a great example of how plants and animals respond to the flood pulse. This floodplain is very dynamic; the main channel is never in the same place for very long (Figure 1.2). High-resolution remote sensing, coupled with very detailed ground truth studies, have allowed scientists to map the distribution, abundance, and growth of biota within the shifting habitat mosaic (sensu Stanford et al. 2005b) of this floodplain in great detail (Figure 1.3). The parafluvial zone expands and contracts with flooding as cottonwood, willows, and alder generate seedlings during periods of minimal flooding and are washed away during big floods. The orthofluvial zone is built up by deposition of fine sediments, allowing old growth stands of cottonwood and spruce to develop. Wetlands exist in depressions throughout the floodplain, further increasing habitat diversity. Nearly 70% of the vascular plants known in the region occur on this floodplain as a consequence of the shifting habitat mosaic. Other groups of biota are similarly diverse. Thus, the floodplain is in a constant state of change, allowing many species to coexist (Stanford et al. 2005b).

FIGURE 1.2 (A) A satellite multispectral image of the Nyack Floodplain habitat catena (Middle Flathead River, Montana 2004). Most, but not all, elements given in Table 1.1. are found on this floodplain. The floodplain extends laterally to both valley walls and is essentially a bowl filled with gravel and rock with a thin veneer of fine sediment and gradually developing soils on the higher-elevation benches that are not scoured by flood flows. Much of the gallery forest of cottonwood and spruce has been cleared for hay farming. Owing to the porous nature of the valley bedsediments, a legacy of river deposition since glaciation, river water downwells into the alluvial aquifer beginning at the upstream knickpoint where the river becomes unconstrained by bedrock. The downstream knickpoint defines entry into another bedrock-constrained canyon, which impounds the alluvial aquifer, allowing it to intersect the surface creating spring brooks and wetlands as water flows from the aquifer back into the river. (B) Here the position of the main channel during 1945–2004 has been color coded to emphasize the dynamic nature of the river (Flathead Lake Biological Station, unpubl. data).

FIGURE 1.3 (A) Hyperspectral data for the image in Figure 1.2.A. of the Nyack Floodplain have been classified into various vegetation types (1 m resolution) using geographical information software (GIS) and validated using ground truth surveys. Inset (B) is a high-resolution digital image that has been classified in (C) showing the distribution of depth and velocity of the water in the image along with the same vegetation types as in (A). Classification of such attributes allows spatially explicit determination of the distribution and abundance of floodplain habitat used by fishes and wildlife (Flathead Lake Biological Station, unpubl. data).

To underscore this point, again consider the Amazon. This great river has existed for millions of years, allowing its biota to evolve highly specialized life histories and by microclimatic influences of the floodplain; may have slope wetlands from with disjunctive floodplain vegetation. morphologies in response to long-term dynamics of the river environment. Seemingly countless aquatic and semiaquatic species coexist, each trying, and variously succeeding, to grow and reproduce in accordance with evolved life history traits and within the myriad of environmental gradients expressed by the dynamic course of the river through the massive catchment basin. For example, the adaptive radiation of Amazonian fishes is astounding, ranging from deep-water specialists that reside in the dark depths of the scoured channels to species that reproduce exclusively in the floodplain forests during floods (Junk et al. 2000, Lowe-McConnell 1987, Petrere 1991). Perhaps even more profound are interpretations of satellite-derived images that strongly suggest the enormously complex and highly evolved rain forests of the Amazon Basin are composed of a mosaic of successional stages created by the river cutting and filling its way back and forth across this huge landscape century after century (Colinvaux 1985, Salo et al. 1986).

We can conclude from studies on the Amazon and many other river systems that the first task of a river ecologist is to determine the appropriate scale of study to answer any particular question at hand (Poole 2002). Do I need to examine the problem in the context of the entire river continuum from headwaters to the ocean or will a particular reach or even a particular riffle or pool suffice?

Moreover, this dilemma of spatial scale is complicated by the fact that the full range of biophysical features of rivers may change suddenly as a consequence of intense, unusual events like very large floods, extended droughts, catchmentwide fires, earthquakes, volcanic eruptions, and other natural phenomena that may radically change conditions reflected by the long-term norm (Schumm and Lichty 1956, Stanford et al. 2005b). So what time period needs to be encompassed by a study in order to adequately understand the ecological significance of natural disturbance events?

And, of course, natural variation in time and space is superimposed upon environmental change induced by human activities in catchment basins. Native people have always been a part of riverscapes worldwide, shaping it to their needs by diverting flows for irrigation of crops or increasing wetland plants, burning forests to increase berry shrubs and harvesting riverine biota. Native societies simply moderated the shifting habitat mosaic, whereas modern societies have vastly altered the process. Flows in all of the larger and most of the smaller rivers in the temperate latitudes of the world now are regulated by dams and diversions, and the tropics are under siege (Dynesius and Nilsson 1994, Nilsson et al. 2005). Reduced volume and altered seasonality of flow radically change the natural habitat template, eliminating native species and allowing invasion of nonnatives. In many cases water from dams is discharged from the bottom of reservoirs, drastically changing temperature patterns and armoring the river bottom by flushing gravel and sand and leaving large boulders firmly paving the bottom. Problems related to flow regulation in other cases are exacerbated by pollution and channelization (Petts 1984). A wide variety of other human effects can be listed (Table 1.1). The cumulative effect is the severing or uncoupling of the complex interactive pathways that characterize the four-dimensional shifting habitat mosaic of riverscapes. Generally, the result is a vastly less dynamic environment than occurred naturally that substantially compromises biota that are adapted to the shifting habitat mosaic often allowing invasion of nonnative, noxious species (Stanford et al. 1996).

II. GENERAL DESIGN

A. Analysis at the Riverscape Scale

The purpose of this chapter is to provide a riverscape or ecosystem context for the other chapters in this book, which teach detailed and more site-specific analyses of river ecological processes and responses. The premise is that few river research and management questions can be answered without considering riverscape attributes and dynamics and very often, issues outside the catchment basin may also be very important. Indeed, almost all natural resource management questions have to be addressed in a whole basin or river ecosystem context owing to overlapping jurisdictions and the interactive nature of ecological processes that provide riverine goods (clean water, fisheries, wildlife) and services (transportation, water power, floodplain fertilization) that humans require. However, ecosystem boundaries are permeable with respect to energy and materials flux and often are best determined by the nature of the ecological issue or question of concern (Stanford and Ward 1992).

Consider the problem of conserving wild salmon around the world. Wild salmon have steadily declined worldwide due to overharvest and vastly altered habitat conditions in many of their natal rivers. For example, at least 20 million Pacific salmon and steelhead historically returned to the Columbia River to spawn. Over 200 different runs (populations) of the five most abundant species occurred as a result of thousands of years of adaptation to the shifting habitat mosaic and the high productivity of the very complex riverscape of this huge (567,000 km²) catchment basin. Adult salmon returned with great fidelity to specific sites along the entire river corridor, including headwater streams and lakes in many of the tributaries (e.g., Snake River Subbasin). Juveniles moved around a lot, often focusing on floodplain habitats and grew on the rich food sources provided by the shifting habitat mosaic. Populations of some species stayed in the river only a few months, while others stayed for three to five years. This same life history plasticity occurred in the ocean with some returning to spawn after only one or two years, while others such as the huge Columbia River chinook (locally called June hogs for the timing of the run and their 25 kg+ body size) fed for several years in the ocean before returning. This life history plasticity underscores the ability of salmon species to adapt their life cycle to local conditions encountered. The Columbia River encompasses 15 ecoregions, thus presenting many different shifting habitat venues for salmon to use, and the result was a very high diversity of locally adapted populations. Entrainment of salmon carcasses in the riparian zone increased fertility (salmon die after spawning, steelhead do not) in addition to providing food for a wide variety of wildlife and humans living along the river and its many tributaries. Thus, the predevelopment Columbia was a natural salmon factory that supported thousands of native people (Stanford et al. 2005a, Williams 2006).

Of course, today the Columbia River and almost all of its tributaries are completely harnessed by hundreds of dams that vastly alter natural flow patterns. Almost the entire mainstem is impounded by hydropower operations making salmon migration problematic. Floodplains either are flooded by reservoirs or severed from the river channel by highways, railroads, and encroaching towns and cities. Farms and industries of all sorts have been developed by diverting water from the tributaries and the mainstem. Billions of dollars have been spent to recover salmon in the Columbia River since 1990 to little avail. Indeed, only one really robust run remains, fall chinook that spawn and rear to smolts (ocean going juveniles) in the Hanford Reach, the last free flowing stretch of the mainstem river (Stanford et al. 2005a, Williams 2006).

The situation is not much better in most of the other salmon rivers of the world, except those in the far north where the shifting habitat mosaic remains unaltered by human activities. Salmon have been lost altogether in most European Rivers such as the Rhine River where they were once abundant.

But owing to their iconic and economic status in local cultures along rivers where salmon were once abundant, people want the salmon back and are willing to pay for it. The challenge for river ecologists is how to allow use of the rivers for the full array of human demands and at the same time provide habitat for salmon. At least two main issues must be considered. First, one has to realize that the ecosystem of the salmon includes the entire river system as well as its estuary and a large area of marine environment, and that for Pacific salmon by example, means most of the North Pacific Ocean where they migrate from one feeding area to another depending on ocean conditions. So far, managers have not tailored harvest of salmon to account conservatively for variation in ocean, estuary, and riverine conditions that salmon will encounter during their long life cycle, and the result has been years of overkill that has eventually reduced the runs to the point that they cannot be sustained in spite of their natural plasticity to environmental variation. Second, the shifting habitat mosaic that salmon require in freshwater has to be provided by restoring normative flow to the natal rivers (Stanford et al. 1996, Hauer et al. 2003, Hauer and Lorang 2004, Stanford et al. 2005a). In many systems, like the Columbia, this can only be reasonably done on certain tributaries that do not have large hydropower dams and other infrastructures that people are not willing to give up in spite of general favoritism for salmon. Other issues such as climate change and use of hatcheries to mitigate lost habitat also are problematic (for more information about salmon, see www.wildsalmoncenter.org).

On a smaller scale, but with equally interactive research and management issues in river ecology, is the Flathead River-Lake ecosystem in northwestern Montana and southeastern British Columbia, Canada (Stanford and Ellis 2002). It is a large (22,241 km²) subcatchment of the Columbia River that was historically unavailable to salmon owing to natural barrier falls that prevented upstream migration. The catchment encompasses small urban and agricultural lands on the piedmont valley bottom, extensive national (US) and provincial (BC) forests with forest production and wilderness management zones, and the western half of the Glacier-Waterton International Peace Park, an International Biosphere Reserve and World Heritage Site. The altitudinal gradient extends some 3400 m from the highest points on the watershed to Flathead Lake. Indeed, the flow of the river begins on Triple Divide Peak, the crown of the continent where three of the great rivers (Columbia, Saskatchewan, and Missouri) of North America begin. The riverscape of the Flathead is multifaceted, with crystal mountain streams cascading through steep mountain valleys that contain abundant populations of Rocky Mountain wildlife, including one of the two last populations of grizzly bears in the United States (the other is in the Greater Yellowstone Ecosystem). The river system includes the Nyack Floodplain just described, where the concept of the shifting habitat mosaic was developed and other expansive floodplains along each tributary and the main stem in the Flathead Valley that flows into 480 km² Flathead Lake, the largest lake in the western United States and among the cleanest in the world for large lakes that have significant human populations in the catchment basin.

But the Flathead is under the same pressures that most river and stream systems endure. The limnology of Flathead Lake and its river system has been studied for over 100 years by scientists at the Flathead Lake Biological Station of the University of Montana. This record clearly shows that water quality is gradually declining in direct relation to development of the human infrastructure in the basin. In recent decades, the decline in water quality has accelerated in response to very rapid population expansion. Driven by strong desire to sustain high water quality, particularly the amazing transparency of Flathead Lake, and the very clear demonstration of change for the worse by the scientists, citizens of the Flathead supported construction of modern sewage treatment plans throughout the catchment and effectively implemented land use regulations to minimize diffuse runoff of pollutants from cities, farms, and logging operations. This is a success story for river management, although continued vigilance and careful river and lake monitoring is required.

However, a continuing major problem for river ecologists in the Flathead is the change in the food web structure of Flathead Lake. Species of fish and invertebrates were introduced to increase fishing opportunities, actions that were scientifically uninformed. Indeed, the abundant native trout, the cutthroat, began to decline when landlocked red salmon (kokanee) were introduced, along with lake trout, lake whitefish, bass, and other species. The native predatory fish, the bull charr, adapted to feeding on kokanee as their native prey, the cutthroat, declined. Bull charr (and cutthroat trout) migrate from the lake to specific tributaries to spawn. Juveniles stay in the river system for several years before migrating to the lake to mature. Thus, the life cycle is rather like salmon in that the lake and river system encompass the bull charr’s life history ecosystem. Bull charr persisted happily in Flathead Lake until mysid shrimp (Mysis relicta) were introduced with the thought of increasing productivity of kokanee through added mysid forage. The introduction backfired badly because it turned out that the mysids ate the food of the kokanee, but the kokanee could not in fact forage on mysids because the mysids were only active at night, whereas kokanee are daytime feeders. This effectively eliminated the formally abundant kokanee from the lake. At the same time the mysids provided abundant new forage for lake trout and lake whitefish that were previously impoverished by having poor food resources for early life stages and were only very slowly expanding. The new mysid forage was ideal for juvenile lake trout and lake whitefish and allowed these species to expand rapidly at the expense of the bull trout, which declined precipitously. Today the lake is dominated by nonnative fish. The native bull charr, cutthroat, and other native fishes are in danger of extirpation from the system. In addition, the now abundant nonnative species have emigrated upstream and colonized lakes in Glacier National Park, presenting yet another dilemma for river managers. The Federal Endangered Species Act and the charter of the National Park system in the United States require conservation and protection of native species. This will be decidedly problematic in the Flathead, owing to seemingly irreversible food web changes promulgated by past management mistakes.

These examples underscore the importance of understanding river and stream systems in a riverscape ecosystem context. A clear definition of the ecosystem boundaries that influence environmental problems is required. The bottom line is that today’s stream ecologist must be broadly trained, attuned to a multidisciplinary, riverscape approach to problem solving, and fully informed scientifically to do the job right.

III. SPECIFIC METHODS

A. Basic Method 1: Boundaries and Hydrography of the Catchment Basin

Catchment boundaries are the ridges that separate a catchment basin from those adjacent. Technically, the catchment boundaries should be termed watersheds. However, in the United States watershed often is considered synonymous with catchment basin. The hydrography (spatial distribution of aquatic habitats) of a catchment basin can be conveniently examined at 1:24,000 scale using maps available from the United States Geological Survey.

1. Using larger-scale maps of your research area, determine catchment basin boundaries for a region of at least 10, 000 km². Choose one catchment of at least 100 km² area for detailed examination. Using a planimeter, determine the total area of the basin.

2. Note the stream network, shown in blue on most maps. Compare the detail of the catchment on different scale maps. The smallest streams begin at higher elevations (e.g., snowfields, lakes, wetlands, or springs). Groundwater aquifers often erupt from hillsides via upslope infiltration of precipitation through porous soils or bedrock. In many cases the smallest stream channels are shown as broken lines, which indicate that surface flow is intermittent.

3. If many intermittent stream channels are shown, the catchment basin is either very dry or the substrata are very porous. In both mesic (wet) and xeric (dry) landscapes, a large amount of the runoff may follow subterranean (groundwater) pathways through porous substrata (see Stanford et al. 2005b). Differentiate intermittent and permanent stream channels in your catchment.

4. An important point to keep in mind is that the drainage network really is a geohydraulic continuum; that is, the stream corridor has both surface and groundwater components, and these interactive pathways are hydrologically and ecologically interconnected (Gibert et al. 1994). Water flowing at the surface at one place may be underground at another, depending on the geomorphology of the catchment basin and the volume and timing of rainfall or snowmelt. Hence, interaction zones between surface and groundwaters are fundamental attributes of landscapes and are very germane to stream ecological studies. Compare topographic, geologic, and groundwater maps of your catchment and identify potential areas of near surface ground waters that may be fed by surface waters or discharge into the stream network.

5. Stream order is determined by the coalescence pattern (see Figure 1.1 and Chapter 4, Figure 4.1). Two first-order streams converge to form a second-order stream, two second-order tributaries form a third-order stream, and so on. Network density is related to geologic origin of the basin, time since uplift, precipitation patterns, precipitation history, types of vegetation present, and resistance of substrata to erosion and infiltration. Lay out a series of maps covering the study catchment at 1:24,000 scale. Overlay the maps with clear plastic or acetate sheets. On the plastic sheets, color-code the different stream orders with markers and tabulate them on a data sheet. Measure length of all streams within the catchment, using a map wheel. Simply trace the stream corridor with the map wheel starting at zero and reading the distance on the appropriate scale of the wheel. Calculate drainage density of the catchment as total stream length divided by total area of catchment.

6. Observe the altitudinal gradient from highest to lowest elevation in the catchment. Carefully consider the density of topographic isopleths (lines of equal elevation). Where they converge closely adjacent to and across the stream channel, canyon segments exist. More widely spaced isopleths indicate flatter topography. Use the acetate sheets overlaying the topographic maps set up in step 5 to locate gradient breaks.

7. Identify canyons (downcutting channels confined by bedrock walls) and alluvial (aggraded, unconfined channels with wide, terraced floodplains) stream segments. In many cases alluvial deposits will be shown by special designations on the maps. Check the map key for such designations. In alluvial zones you may observe that the stream channels begin to braid, which suggests major deposition and floodplain development. On alluvial reaches of bigger streams, the general structure of the floodplains will likely be evident in the form of active zones of flood scour and terraces at higher elevations along the channel. Using elevation data from the topographic maps, plot the stream profile from highest to lowest elevation (x-axis = distance downstream; y-axis = elevation). Label the major gradient breaks and alluvial reaches.

8. Streams may flow into lakes or wetlands. In some cases wetlands may remain where lake basins have filled with sediments. In glaciated landscapes, lakes may occur in high-altitude cirques; larger, often very deep lakes may occur singly or in a series in the glaciated mountain valleys. Many lakes and wetlands are fed and drained by groundwater and determination of underground flow pathways may require geohydrologic surveys. Consult Wetzel (2001) for detailed descriptions of the types of lakes and modes of origin. The main point here is to note the position and potential influence of lakes on the stream network of your catchment basin. Lakes function as sinks for fluvial sediments, nutrients, and heat. Streams flowing from lakes may well be very different than inflowing streams. Manmade reservoirs function in similar fashion, except that ecological influences on rivers below the dams will depend on the depth and mode of water release from the dams (Stanford et al. 1996, Poff et al. 1997). Tabulate lakes and reservoirs in your catchments, noting elevation, area, and other available data (e.g., volume, flushing rate).

B. Basic Method 2: Other Landscape Attributes of the Catchment Basin

The maps provided likely will show surficial geology, groundwater resources, broad vegetation categories, precipitation patterns, and human infrastructures (roads, pipelines, dams, railroads, urban areas, or individual buildings, etc.). Systematic summarization of these features in relation to the hydrography will provide valuable insights about potential influences on water quantity and quality and constraints on distribution and abundance of riverine biota. For example, an understanding of the general geology of the catchment basin will provide insights into discharge, water chemistry, distribution of biota, and other attributes of the catchment basin that likely will be encountered in fieldwork. Igneous and metamorphic rocks generally do not dissolve much in water, and, hence, surface waters draining such formations have low dissolved solids and little buffer capacity, whereas waters from limestone formations generally may be expected to contain high amounts of dissolved solids and be very well buffered.

Land use patterns inferred from the distribution of human infrastructures shown on the maps can be corroborated from aerial photographs and satellite images. Google Earth and other Internet map tools allow a quick view of the riverscape (http://earth.google.com/). If the photos are available in a time series, changes in hydrography (e.g., channel migration on floodplains) as well as changes in land use patterns can be observed.

1. Using a map wheel and planimeter for the maps (may use digitizing tablet and computer if available) and a stereoscope for aerial photos of known scale, determine the lengths and areas of various features on the landscape of the river catchment you have chosen for study. Create a table or computer spreadsheet in which you can record the different landscape attributes identified in the steps below. Record the features by stream length, area, or other spatial measures. This will provide a basis for a general description of the study catchment and landscape attributes that may influence ecological processes and responses within the stream network.

2. Compare the catchment basins you have identified on the topographic maps with geologic maps of the region. On granitic and other hard rock mountains, runoff usually is dominated by surficial flow, whereas limestone and other sedimentary and volcanic formations may allow considerable infiltration and runoff may predominately follow groundwater pathways to portals back to the surface at lower elevations. Subsurface drainage networks dominate in karst (cavernous limestone) landscapes (see Mangin 1994). Tabulate the major geologic formations by type and percent of catchment basin area. Use a planimeter to determine areas of different geologic formations.

3. Determine vegetation cover patterns within the catchment basin. At a minimum the topographic maps should show forest or grassland areas in green and exposed bedrock or other nonvegetated (e.g., clear-cut forest stands) areas in white. Glaciers and wetlands likely will have special designations shown in the map key. Vegetation maps of your catchment may be available or you may be able to use aerial photos to determine the general pattern in comparison to the topographic maps. Using all available maps and photos determine at a minimum riparian (stream side), wetland, and upland (forest and grassland) ground cover for the entire catchment basin. For montane regions it is instructive to differentiate forest types with respect to altitude (e.g., riparian, upland forest, subalpine forest, alpine). Again use the planimeter to determine areas of cover types and record percent of basin area by type.

4. Examine the stream corridors on the topographic maps for features created by human activity, such as revetments, bridges, irrigation diversions or returns, mines, and other industrial sites. All of these may change flow patterns or otherwise influence the natural attributes of the stream corridor. On the acetate sheets, color-code stream segments by type of alteration or land use. Tabulate percent of stream corridor and/or catchment basin potentially influenced.

5. If aerial photos are available, verify all the features you have identified in the catchment basin(s) from interpretation of maps. Add notes for features more evident in the photos, such as riparian forests or stream channels. Can you identify a subset of the habitats given in Table 1.1? Keep in mind that the maps and photos may have been produced on very different dates and therefore show differences in the landscape features.

6. Note any discharge or precipitation gauging stations in your catchment basin. These are sometimes included on topographic maps. Prepare time series plots of available data for these stations and calculate unit area precipitation and runoff. Determination of stream flow is discussed in more detail in Chapter 3, but knowing stream flow dynamics at various points in the stream network will provide a more complete view of the catchment landscape as derived in this chapter from maps and photos.

C. Advanced Method 1: Computerized Spatial Analyses of Riverscapes

While maps and photos are basic tools for understanding how your study basin fits into the regional landscape, digital approaches provide a means for examining landscapes in great detail. All points in any landscape can be precisely known from geodetic surveys. In fact, that is how the topographic maps used above were created. With the aid of a computer, topography can be reduced to a digital data base using algorithms that interpolate between surveyed points. Using software that is widely available, the computer operator can produce three-dimensional images of any digitized landscape. Topographic data can then be examined statistically or plotted in relation to any other spatial data bases (e.g., stream network, water quality, fish distribution).

A number of software packages that manipulate digitized data in relation to geographic references are available under the general descriptor of geographic information systems (GIS). Considerable computer sophistication is required to use a GIS properly, although most can be run on high-speed personal computers. The advantage of a GIS is that landscape data for many variables can be created in layers superimposed in relation to the topography (Figure 1.3). This is a very useful way to accurately keep track of and display landscape change over time. For example, observed fish distributions within a catchment basin can be plotted in true spatial (geographic) context with the hydrography and, if time series data are available, changing fish distributions can be shown in spatial relation to changes in potentially controlling variables, such as land use activities. Hence, a GIS permits very large data sets to be systematically arrayed and related in time and space in a manner that facilitates interpretation of landscape pattern and process (Bernhardsen 2002, Longley et al. 2005).

Moreover, data describing landscape patterns in some cases can be derived from spectral (reflectance) data gathered from satellite or other remote sensors. In this case a GIS is essential to relate massive amounts of spectral data for entire landscapes to the actual topography. Different wave lengths of light are reflected by the pattern of landscape attributes on the ground. Hence, algorithms or statistical models can be derived that relate measured spatial variation for a portion of the landscape (ground truth data) to the variation in the spectral patterns recorded remotely. The algorithms then can be used to generate landscape data layers in direct relation to the topography (Lillesand and Klefer 2000). Obviously, some landscape variables are better suited to spectral imagery than others, and considerable ground truthing is needed to verify the accuracy of the remotely sensed data. For example, water bodies are easily distinguished from terrestrial environs; coniferous forests can be distinguished from grasslands. But this technology is in a rapid state of development and should be approached with caution and a clear understanding of the research or management question.

Most research universities have spatial analysis laboratories. If a GIS is not available to demonstrate utility in landscape analysis of catchment basins, I recommend that an active spatial analysis lab be toured to clearly convey the usefulness of this technology in demonstrating pattern and process at the level of entire catchment basins.

D. Advanced Method 2: Identifying Ecosystem Problems at the Landscape Scale

Now that you have summarized landscape features of your catchment basins, it is important to consider what sorts of questions or problems require resolution at a landscape scale. Almost all natural resource management questions have to be addressed to some extent in a landscape context, owing to overlapping jurisdictions. For example, in the Flathead catchment just described, nearly all federal (US) land management

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