July 2024 Wetland Science & Practice by Society of Wetland Scientists

Summer has arrived in New England. The other evening, I saw the flickering of lightning bugs or fireflies which is one sign of summer that I’ve looked forward to since my childhood. As a kid and still as an adult I’m bedazzled by their blinking lights in the dark of night...a land-based example of bioluminescence. Males probably do most of the flashing while in flight in hopes of attracting a female who will flash back if interested. In North America, there are over 150 species representing 16 genera and over 2,000 species of lightning bugs worldwide. Perhaps the most famous are the synchronous fireflies of the Congaree Swamp (South Carolina) – one of three synchronous species whose displays are virtually unrivaled. From mid-May to mid-June these fireflies put on their show in the Swamp. The event is in such demand that the National Park Service now maintains a lottery system for attendance. Another local sign of summer is the blooming of Mountain Laurel (Kalmia latifolia) and I’ve got a huge one about 12 ft tall that resembles a tree in the Serengeti as it stands alone in an open field of ferns.

With this issue, we welcome incoming SWS President Eric Stein and thank outgoing President Susan Galatowitsch for her leadership during the past year (see their

messages). The July issue of WSP is normally devoted to presenting abstracts from our annual conference. However, this year, the conference is being held in Taiwan from November 11–16, so its proceedings will be in the January 2025 issue. So, in the current issue, we have a number of articles along with SWS News and other information (still looking for an Assistant Editor for WSP). The first article is about scientists who pioneered work in monsoonal wetlands in India written by Arnold van der Valk; another contribution to his series of early wetland scientists. The other articles deal with topics such as the Corps of Engineers’ management of Lake Red Rock (Des Moines River, Iowa), the potential of artificial floating wetlands for stormwater treatment in the Pacific Northwest, and the challenges faced by local fishermen in protecting wetlands from degradation from agriculture in Veracruz, Mexico. In addition, we also have two submissions for Notes from the Field – one from two wetland scientists from Mexico on their observations in Quintana Roo and the other from my recent observations from the New Jersey Pine Barrens – two very different ecosystems (temperate vs tropical wetlands).

As usual, we appreciate the contributions and thank the authors for their submissions. We’re looking for articles for the October issue - if interested in writing an article, feel free to contact me at ralphtiner83@gmail.com. SWS members and other readers are interested in hearing about wetland projects and experiences you have. Meanwhile, hope you enjoy this issue.

Happy Swamping!

Ralph Tiner WSP Editor

Vol. 42, No. 3 July 2024

ISSN: 1943-6254

210 / From the Editor’s Desk

212 / President’s Address

213 / Outgoing President’s Message

214 / SWS Webinars

215 / SWS News

254 / Notes From the Field

261 / Wetlands in the News

262 / Wetland Bookshelf

263 / SWS Submission Guidelines

264 / 2023 Advertising Prospectus

ARTICLES:

217 / Western Science Discovers Indian Monsoonal Wetlands: Winfield S. Dudgeon and Walter T. Saxton Arnold van der Valk

224 / Advancing Lake Red Rock Reservoir Management Practices to Maximize Ecological Benefits: From Planning to Monitoring Chuck Theiling, Alyssa Calomeni, Nicole Bosco, Steve Dinsmore, Hugh Howe, Todd Gosselink, Keith Schilling, Matthew Streeter, and Perry Thostenson

231 / Floating Treatment Wetland and Biomedia Module for Stormwater Treatment and 6PPD Quinone Removal

Lizbeth Seebacher, Brianna Pierce, and Robert Turner

242 / The Use of Wetlands by Fishermen in the Region of the Lower Papaloapan River Basin (Veracruz, Mexico)

Blanca Edith Escamilla Pérez, Martha Judith Hernández Velasco, Xochitl del A. León Estrada, and Hugo López Rosas

&Wetland Science Practice

PRESIDENT / Eric Stein, Ph.D.

PRESIDENT-ELECT / Rebecca Pierce

IMMEDIATE PAST PRESIDENT / Susan Galatowitsch, Ph.D.

SECRETARY GENERAL / Kai Rains, Ph.D.

TREASURER / Yvonne Vallette, SPWS, SWSPCP

EXECUTIVE DIRECTOR / Erin Berggren, CAE

MARKETING MANAGER / Moriah Meeks

WETLAND SCIENCE & PRACTICE EDITOR / Ralph Tiner, PWS Emeritus

CHAPTERS

ASIA / Wei-Ta Fang, Ph.D.

CANADA / Susan Glasauer, Ph.D.

CENTRAL / Lindsey Postaski

CHINA / Ming Jiang

EUROPE / Matthew Simpson, PWS

INTERNATIONAL / Alanna Rebelo, Ph.D. and Tatiana Lobato de Magalhães, Ph.D., PWS

MID-ATLANTIC / Bill Morgante

NEW ENGLAND / April Doroski

NORTH CENTRAL / Casey Judge, WPIT

OCEANIA / Maria Vandergragt

PACIFIC NORTHWEST / Shelby Petro

ROCKY MOUNTAIN / Rebecca Pierce

SOUTH ATLANTIC / Richard Chinn

SOUTH CENTRAL / Jessica Brumley

WESTERN / Richard Beck, PWS, CPESC, CEP

SECTIONS

BIOGEOCHEMISTRY / Katie Bowes

EDUCATION / Darold Batzer, Ph.D. and Derek Faust

GLOBAL CHANGE ECOLOGY / Melinda Martinez, Ph.D.

PEATLANDS / Bin Xu, Ph.D.

PUBLIC POLICY AND REGULATION / John Lowenthal, PWS

RAMSAR / Nicholas Davidson, Ph.D.

RIGHTS OF WETLANDS / Gillian Davies

STUDENT / Deja Newton

WETLAND RESTORATION / Luke Eggering

WILDLIFE / Rachel Fern

COVER PHOTO:

Swamp Azalea (Rhododendron viscosum) blooming in the New Jersey Pine Barrens in June. (Photo by Ralph Tiner)

WOMEN IN WETLANDS / Mo Wise

COMMITTEES

AWARDS / Amanda Nahlik, Ph.D.

EDUCATION AND OUTREACH / Jeffrey Matthews, Ph.D.

GLOBAL REACH / Rebecca Woodward

HUMAN DIVERSITY / Christina Omran

MEETINGS / Yvonne Vallette, PWS

MEMBERSHIP / Kai Rains, Ph.D.

PUBLICATIONS / Keith Edwards

WAYS & MEANS / Yvonne Vallette, SPWS, SWSPCP

WETLAND CONCERNS / Max Finlayson

WETLANDS OF DISTINCTION / Roy Messaros, Ph.D., Steffanie Munguia and Jason Smith, PWS

REPRESENTATIVES

PCP / Christine VanZomeren

WETLANDS / Marinus Otte, Ph.D.

WETLAND SCIENCE & PRACTICE / Ralph Tiner, PWS Emeritus

NAWM / Samantha Vogeler

Eric Stein, Ph.D. SWS President

Dear SWS Colleagues, It is an honor to be serving as your President for the coming year. I would like thank Sue Galatowitsch for her leadership over the past year, and I look forward to working with her, the rest of the Executive Board and all the amazing volunteer leaders in SWS over the coming year. As Sue mentioned in her message, this will be an exciting year for the Society and there are many opportunities to get involved. This coming year, we are excited to be partnering with the Taiwan Wetland Society to host our annual meeting in Tiawan – I hope to see many of you there. We will also be continuing our work toward recruiting the first Executive Director in the history of the Society, which will position us to enhance our strategic actions, our partnership with other scientific societies, and service to our membership. Our five-year strategic plan will be updated beginning this year and we will continue to grow our membership particularly with students, early career professionals and wetland scientists and practitioners from outside of North America.

The strength of SWS is the grass-roots participation and commitment across the academic, government, NGO, and private-practitioner communities. I encourage every SWS member to find the way that works best for them to get involved, whether that be on Committees, in local Chapters, in Sections, or by participating in events such as webinars, mentoring groups and local meetings. These interactions are a great way to connect with your colleagues, form partnerships and friendships, and stimulate new opportunities. Collectively, these engagements are what makes SWS function and what allows it to provide its service to our members and the larger wetland community.

I recently had the chance to visit some of the remnant blanket bogs of Ireland, 75% of which have been lost. Experiencing these amazing wetlands reinforced the importance of the work we all do every day to protect, restore, manage and increase understanding and awareness of the function and importance of the world’s Wetlands. I look forward to working with all of you to enhance the role of SWS in supporting these efforts through service to our membership.

I hope to see you in Tiawan and in workgroups over the course of the year.

Warmly,

Eric Stein President,

SWS

Ph.D.

University of Minnesota

Immediate Past President

Dear Colleagues, I’ve enjoyed serving as SWS President this past year and working with many of you to advance our work as wetland scientists. SWS is truly a “bottom up” organization that functions as well as it does because most of our activities to promote wetlands are regionally focused through chapters or topically oriented through sections. SWS sustains its momentum because of our incredible network of volunteer leaders. It takes approximately 185 people serving in leadership roles (i.e., as officers or committee members) to keep the 37 groups that make up SWS moving forward. That’s about 7% of SWS members! Most of us (including me) spend most of our years as SWS members not in leadership positions, but benefiting greatly from our collective corps of volunteer leaders. What’s great about stepping up to take your turn as a SWS leader is that the benefits to you are even greater. It’s hard to overstate how enriching my

year as SWS President has been to me – getting to know so many of you and to be inspired by your efforts.

Throughout the year, I’ve occasionally reflected on how much of a difference individuals can make in organizations like SWS. Whether it’s revitalizing a committee, starting a new section, hosting a meeting, launching a new initiative, mentoring a new wetland professional, or reliably producing a publication – we are fortunate to have dedicated members committed to SWS. Thank you!

I look forward to working with you in the coming year as I continue on the Executive Board as Immediate Past President. The year ahead is a crucial one for moving forward on building our capacity as an organization with an executive director, for supporting emerging chapters around the world, for strategic planning, and to ensure we efficiently and effectively facilitate the work of all chapters, sections and committees.

Thanks again for your contributions to SWS and, as importantly, to your collegiality! Hope to see you at the 2024 Annual Meeting in Taiwan!

Sue Galatowitsch Immediate Past President, SWS

Susan Galatowitsch,

English:

July 18 | 1:00 PM ET

Topic: Prioritizing Floodplain Reconnection to Improve Ecohydrological River Corridor Function

Speaker: Liz Doran

August 15 | 1:00 PM ET

Topic: TBD

Speaker: TBD

September 19 | 1:00 PM ET

Topic: TBD

Speakers: Royal Gardner, Bob Kerr, James Thomas

Spanish:

September 25 | 1:00 PM ET

Topic: TBD

Speakers: Sergio Alejandro Guarín Torres and Jenny Patricia Veloza Torres

NOTE: Webinar Topics and Speakers are subject to change. Visit the SWS Event Calendar for the most recent details and for future webinar dates.

THANK YOU TO OUR 2024 WEBINAR SERIES SPONSORS

EARLY BIRD REGISTRATION ENDS JULY 15TH!

The SWS 2024 Annual Meeting will be here before you know it, and the meeting planners are working hard to deliver an unforgettable inaugural SWS meeting in Asia! The theme of the 2024 SWS Annual Meeting is “Wetlands and Global Change: Mitigation and Adaptation.” Wetland contributions to biodiversity, carbon storage, climate change, and public safety will be highlighted as the world actively responds to global change challenges. This conference is being hosted with National Park Service, Ministry of the Interior, Taiwan, Republic of China (ROC) and co-hosted with the Asia Chapter of the Society of Wetland Scientists and will be the first SWS Annual Meeting held in Asia, marking a new era for the growing importance of Asian wetlands and contributions being made by Asian wetland scientists.Visit the SWS 2024 Annual Meeting website to check out information available now like:

• a list of plenary speakers

• descriptions of field trip offerings

• information on visiting Taiwan

Don’t wait to register! Secure your spot before early bird pricing ends. Get excited to explore the Taiwanese wetlands with SWS.

Opportunity for Career Development — Assistant

Editor of Wetland Science & Practice

Having been the editor of Wetland Science & Practice for a decade or so, it is time to get someone ready to move the journal forward after mid-2025. During my tenure, we’ve been able to take the journal into the digital realm as a fullcolor e-publication and have re-established the process of assigning doi codes to articles to make them more readily available online. To make the transition seamless in anticipation of my retirement by 2026, we’d like to have someone come onboard as an Assistant Editor (AE) for the next year or so with the expectation that the AE would assume the Editor’s position by the end of 2025. The duties would be to help the Editor contact local chapters for possible contributions, review contributions for their suitability for publication and suggest edits, coordinate any additional peer review as necessary, and learn the process of working with our support staff in getting the issue posted online. In terms of a time commitment, most issues require about 3-4 days of work from the Editor so the AE would spend a day or so four times a year. As far as qualifications are concerned, the best candidates would have some experience in writing scientific papers/publications and articles for the general public on the ecology or natural history of wetlands. FYI, the Society’s budget includes a travel stipend for the Editor to attend the Society’s annual meeting. If interested, please send a note to me...Ralph Tiner, Editor WSP at: ralphtiner83@gmail.com. Thanks for your consideration.

SWS-Africa Wetlands Training Course:

First Announcement

We are very excited to announce our 2024 wetlands training course from 7 to 9 October 2024 in Lagos, Nigeria

This 3-day wetlands training course is titled: “Introduction to Wetlands and the Assessment of their Ecological Condition and Ecosystem Services” and aims to equip practitioners, managers, decision-makers, researchers, and students with fundamental wetland skills and knowledge. Please visit our website to learn more!

WHAT IS THE COURSE ABOUT?

• The drivers of wetland ecological condition (hydrology, geomorphology, water quality and vegetation);

• Wetland identification and classification;

• Wetland ecosystem services;

• Available wetland ecological condition assessment tools (the WET-Health and miniWET-Health citizen science tool);

• A brief introduction to wetland rehabilitation concepts; and

• GIS skills for wetland assessments

WHAT DOES IT COST?

Registration Deadline Price (USD) Price (Naira)

Early bird; 31 Aug 2024; $180; ₦270,000

Late registration; 30 Sep 2024; $220; ₦330,000

This covers the following:

• Digital course notes

• Supporting documents and materials for practical assignments

• Digital copies of selected guidelines and tools and other material

• Lunches and teas for three days

• The fieldtrip

• Assessment and certificate

WHO SHOULD ATTEND?

Practitioners, managers, decision-makers, researchers and students whose work currently involves wetlands, or who wish to move into the wetland field of practice. The course is designed at a professional level; thus participants are expected to have a basic degree in natural sciences or equivalent qualification; and will benefit from some knowledge of geography, Geographic Information Systems, soil science, and ecology. This course is suitable both for beginners and those who already have some wetland knowledge.

All are welcome! We hope to meet you there :)

Western Science Discovers Indian Monsoonal Wetlands: Winfield S. Dudgeon and Walter T. Saxton

Arnold van der Valk1

ABSTRACT

The first ecological studies of Indian monsoonal wetlands were conducted by an American missionary and botanist, Winfield Dudgeon, and a British botanist, Walter Saxton. During the 1920s, both studied seasonal changes in the vegetation of depressions on the Gangetic Plain in northern India. Up to 95% of the annual precipitation in this area falls during the summer monsoon (June to September). Consequently, these depressions are flooded during and after the monsoon, and wetland vegetation is found in them. After these depressions go dry, one or more dry land vegetation types, often grassland, are found in them that persist until the next monsoon. Ecologists had not previously described such extreme intra-annual changes in vegetation. Dudgeon and Saxton developed new theoretical frameworks to describe and classify this novel kind of vegetation change. Dudgeon proposed the concept of “seasonal succession.” Saxton rejected Dudgeon’s idea that seasonal vegetation changes were a form of succession. As an alternative, Saxton proposed the concept of “mixed formations in time.” In other words, different vegetation types or phases (wetland or dry land) were found during wet and dry periods each year. Dudgeon and Saxton pioneered the study of the impacts of large water-level changes on wetlands. They demonstrated it was propagules of wetland and upland plant species in the soil that enabled them to survive seasonally adverse environmental conditions, allowing them to persist in depressions from year to year.

INTRODUCTION

“A given area [in northern India] is subject to far greater extremes of humidity than is often experienced in temperate zone habitats. 90 per cent of the rain falls in three months, from the middle of June to the middle of Septem-

ber. During the rainy period, a given area may be a wet meadow, or, if the soil becomes waterlogged and drainage is inadequate, it may, towards the close of the period, become a swamp or a lake. After the rains cease, it gradually dries, and for six months or more is capable of supporting only a xerophytic flora” (Kenoyer 1924).

Although botanists had done significant work on the taxonomy of Indian plants in the 19th Century and early 20th Century, ecological research began only in the 1920s (Barucha 1975; Singh 2011). India’s first ecologists were American missionaries trained as botanists (Winfield Dudgeon and Leslie Kenoyer) who took positions at a Christian college in Allahabad and a British botanist (Walter Saxton) who came to Ahmedabad via South Africa. Although they were familiar with various types of vegetation change, as described by Cowles (1911) and Clements (1916), these pioneering ecologists who grew up and were educated in the temperate zone were ill-prepared to make sense of the dramatic seasonal changes in vegetation found in subtropical Indian wetlands. As noted by Kenoyer (1924), there was no known temperate zone equivalent to the intra-annual changes in vegetation that occurred in the monsoonal wetlands of the Upper Gangetic Plain. Winfield Dudgeon (1920) and Walter Saxton (1922, 1924) believed that the intra-annual vegetation dynamics of monsoonal wetlands could not be accommodated in contemporary theories of vegetation change. Consequently, they had to propose new ones. Dudgeon (1920) proposed the concept of seasonal succession, while Saxton (1922, 1924) proposed mixed formations in time.

MONSOONS AND MONSOONAL

The Indo-Gangetic Plain covers northern and northeastern India and parts of Pakistan and Bangladesh (Figure 1). The plain is bounded on the north by the Himalayas, the source of its rivers, on the south by the Peninsular Plateau, and on the east by the Bay of Bengal. This region is covered by alluvial soils deposited by its major rivers and their tributaries. The Upper Gangetic Plain, which the Ganges River and its tributaries drain, runs about 550 km east-west and 380 km north-south with an elevation between 100 to 300 m. The climate of the Gangetic Plain is subtropical, with three distinct seasons: cool (winter), hot, and rainy (monsoon) (Figure 2). Winters are cool, with average temperatures in January between 11 °C (52 °F) in the north and 15 °C (59 °F) in the southeast. It is hot and dry from mid-March to June before the monsoon’s onset, and temperatures can reach 45 °C (113 °F). During the summer monsoon, which starts in June, temperatures decrease and humidity increases. Annual rainfall ranges from approximately 600 millimeters (23 inches) in the northwest to 1,300 mm (51 in.) in the southeast. The monsoon ends in mid to late September or early October. Nearly all of the region’s annual precipitation (up to 95%) occurs during the summer monsoon. For more information about India’s summer monsoon, see Yadav (2008).

Figure 2. “Mean temperature [thin solid line], mean sunshine (mean cloudiness curve inverted] [dashed line], mean rainfall [hatched areas], and mean relative humidity [thick solid line] for the year at Allahabad, so calculated that all the maxima touch the top of the graph and the minima touch the bottom. This emphasizes the three climatic seasons [rainy, cold, and hot], which determine three corresponding vegetational seasons.” (Dudgeon 1920).

Figure 1. The Indo-Gangetic Plain and its subdivisions. Courtesy of the Union Public Service Commission of India.

The Upper Gangetic Plain has numerous shallow depressions, both natural and man-made. Because of its monsoonal climate, shallow depressions fill with water (up to 3 m deep) during the rainy season, and wetland vegetation develops. These flooded depressions gradually dry out in the following winter and spring months, and their wetland vegetation dies and decomposes, leaving only seeds and perennating organs behind. When they dry out, upland plant communities develop in these depressions. The reflooding of the depressions eliminates this upland vegetation during the next monsoon (Misra 1946; Gopal 1986). Depending on the depth of the depression, the amount of rainfall during the monsoon, grazing, and irrigation withdrawals, the length of time the depressions are dominated by wetland and upland vegetation varies from year to year, as does, to some extent, the composition of the wetland and upland vegetation (Misra 1946).

WINFIELD SCOTT DUDGEON (1886–1932)

Winfield Dudgeon (Figure 3) was born in Hedrick, IA, and died in 1932 in Ames, IA, while on leave from Ewing Christian College. He graduated from Iowa State College (now University) in 1907 and took a teaching position at Central College, Pella, IA. He did his postgraduate studies at the University of Chicago. In 1912, Dudgeon, as a missionary, went to teach at Ewing Christian College in Allahabad (Stewart 1982) and was associated with the College until his untimely death. Allahabad is in the northcentral Indian state of Uttar Pradesh at the confluence of the Ganges and Yamuna Rivers. Dudgeon founded Ewing’s Department of Botany and, in 1920, was involved in the organization of the Indian Botanical Society, serving as its first president.

In 1920, Dudgeon published a paper with the uninformative title, “A contribution to the ecology of the Upper Gangetic Plain,” in the Journal of Indian Botany. It describes the climate, geology, and vegetation within a ten-mile radius of Allahabad. He emphasized the importance and novelty of his study by noting that “For the most part, studies in plant succession have been made in temperate regions, where there is but one vegetational season, the summer or growing season. This is followed by a winter season during which the vegetation is at more or less of a standstill. In the Upper Gangetic Plain, there is no season in which growth is impossible. Growth is checked and the vegetation modified by the aridity of the hot season, and at all seasons and every stage it is interfered with even to the extinction point by the human factors.” For the first time, Dudgeon documented the dramatic seasonal changes in the structure and composition of the vegetation in low-lying areas on the Gangetic Plain.

Dudgeon (1920) described his study area as “… monotonously level. Here and there are slight natural depressions that become shallow lakes during the rainy season, but which are dried up later by evaporation and by use of

the water for irrigation purposes.” He noted the importance of three factors controlling the distribution and composition of the vegetation in monsoonal wetlands: topography (depth of depressions), seasonal climatic changes, and human disturbances, especially grazing by domestic animals. “The climatic factors, rainfall, insolation, temperature, humidity, and air movements, are periodic in distribution, and produce three distinct seasons (Figure 2). (a) Rainy season, from the middle of June to the end of September, with high rainfall, low insolation, high temperature, and high humidity. (b) Cold season, from the first of October to the end of February, with low rainfall, high insolation, low temperature, and high humidity. (c) Hot season, from the first of March to the middle of June, with low rainfall, high insolation, high temperature, low humidity, and large air movement” (Dudgeon 1920). At Allahabad, about 94% of the annual rainfall occurs during the monsoon (rainy season).

In a depression over a year, the vegetation changes from aquatic vegetation to wet meadow to dry meadow. Dudgeon describes this as “seasonal succession.” “A third type of succession is a prominent feature in a strongly periodic climate. It is illustrated by the striking changes in the

Figure 3. Winfield S. Dudgeon around the time of his graduation from Iowa State College. (The Bomb, 1907, ISC Yearbook. Courtesy of the Iowa State University Digital Archives).

aspect and content of the vegetation from season to season and may be called seasonal succession. As a result of the three well defined climatic seasons, rainy, cold, and hot, there are three equally well marked vegetational seasons.”

Dudgeon did his postgraduate work at the University of Chicago, the home of Henry Cowles, one of the most influential early American researchers of vegetation change. To try to make sense of the intra-annual changes in monsoonal wetlands, Dudgeon turned to Cowles’ 1911 paper on vegetation cycles. Cowles (1911) is the only paper on vegetation dynamics cited by Dudgeon (1920).

There had been various models of vegetation change or succession proposed by 1920. Still, all of them had one thing in common, succession was considered an interannual, not an intra-annual, phenomenon. Clements (1916) proposed that succession is a directional and deterministic phenomenon that results in a final stage, the climax, in equilibrium with the regional climate. For Clements, succession typically took hundreds or thousands of years. Cowles (1911) described vegetation changes as nested temporal cycles (climatic, topographic, and biotic) at three different time scales: “Each climatic cycle has its vegetative cycle; each erosive [topographic] cycle within the climatic cycle, in turn, has its vegetative cycle; and biotic factors institute other cycles, quite independently of climatic or topographic change.” For Cowles, vegetation change can occur over thousands or tens of thousands of years (climatic cycles), hundreds or thousands of years (topographic/erosional cycles), and decades or centuries (biotic cycles). To Cowles’ three vegetation cycles, Dudgeon added a fourth, much shorter cycle, seasonal succession, driven by intraannual changes in water levels.

By considering intra-annual changes in vegetation in monsoonal wetlands to be a type of succession, Dudgeon made two missteps. A successional sequence implies that every vegetation stage somehow prepared the way for the next stage. This was widely assumed to be the case in the early 20th Century (Clements 1916). However, this is not the case in monsoonal wetlands. Dudgeon also failed to differentiate his seasonal succession cycle from less extreme seasonal changes in vegetation, a feature of all kinds of vegetation. Although seasonal succession could be a logical extension of Cowles’s cyclical conception of vegetation change, Indian and other ecologists have never embraced Dudgeon’s seasonal succession (Misra 1946, see below). Nevertheless, Dudgeon described a wetland type previously unknown to European and American ecologists. He also documented the importance of water-level fluctuations for understanding wetland vegetation dynamics in India.

WALTER THEODORE SAXTON (1882–1973)

Walter Saxton was born in Great Britain and studied botany at the University of Cambridge, from which he received a Bachelor of Arts. In 1906, he became an assistant to Profes-

sor H.H.W. Pearson in the Department of Botany at South African College, Cape Town. During his seven years at South African College, Saxton published 14 papers, primarily in plant embryology and conifer taxonomy. However, during the summer of 1911–1912, he was involved in a descriptive study of the vegetation of the Manubie District, Cape Province (Saxton and Péringuey 1917). In 1913, Saxton left South Africa to accept an appointment as the professor of botany at Gujarat College in Ahmadabad, Gujarat, India. Later he held positions at Reading University and the University of Cape Town, the successor of South African College.

In 1922, Saxton published two papers on the vegetation of the Gangetic Plain. Dastur and Saxton (1922) is an unremarkable study of factors controlling the distribution of savanna species in an area near Ahmadabad. However, Saxton (1922) is a remarkable paper on seasonal vegetation changes due to north India’s monsoonal climate. Saxton’s 1922 paper was published in the Journal of Indian Botany, the same journal in which Dudgeon had published his 1920 paper.

Saxton (1922), in his Introduction, makes clear why he is publishing this paper: “The writer has always deprecated the action of those persons who evolve new theories, from a priori considerations, out of their own inner consciousness, without any material evidence to support them, as well as of those who glean some facts from half a dozen published sources, diligently select those favourable to a particular pet theory, ignore all the other facts which do not fit it and rush into print. It seems, therefore, advisable to state that the theory to be developed here has not arisen in either of these two ways. It is based mainly on some ecological work which is being carried on at the present time by the writer and some of his students. This work is likely to be continued for some months at least and meanwhile, the idea gradually crystallizing from it seemed sufficiently important, in its relation to Indian ecological problems, to justify this attempt to complete the crystallizing process. It is proposed rather to explain the idea than to give details of the facts which first led to its adoption.” Saxton’s 1924 paper “Phases of vegetation under monsoon conditions” would contain the promised data.

Saxton had an ax to grind but named no names, and his paper contains no references. He takes to task his unnamed adversary because of a failure to recognize that India’s vegetation can never be adequately described or classified using existing Western models of vegetation change. “I know of no work in recent years which has suggested any broad basis upon which detailed ecological studies in India may rest. … The result has been that those who have tried to define Indian plant communities have quite definitely made an attempt to fit them into the systems which have evolved in the last twenty years from the ecological work done in Western countries. Those systems are already comparative-

4. Annual vegetation phases (mixed formations in time) in a low-lying area on the Gangetic Plain, India. (Adapted from

Figure 5. Idealized maps of each plant species in a small plot: (A) during the grassland phase and (B) during the marsh phase. The only species found in both vegetation phases was A — Andropogon annulatus. A = Andropogon annulatus [perennial]; Æ = Æchynomene indica [annual or perennial]; Am = Ammania auriculata [annual]. Cae = Caesulia axillaris [annua]; Cl = Cleome viscosa [annual]; L = Ludwigia parviflora [annual]; M = Melochia corchorifolia [herbaceous perennial]; P = Panicum prostratum [annual]; T = Trianthema monogyna [annual] (Saxton 1924).

ly rigid and the task of fitting our plant communities into them is not an easy one. Indeed I have come to the conclusion that it cannot be done, at least not on the lines which have been hitherto attempted” (Saxton 1922). Although not named, Winfield Dudgeon’s “seasonal succession” obviously is Saxton’s target.

Saxton (1922) goes on to make it clear why Western vegetation models are not suitable for India: “… the great difference between Europe and America on the one hand and India on the other is that the former really have no habitat which even approximately corresponds to the Indian monsoon habitat …. Seasonal differences are found in other habitats, but I believe it must be admitted that they are much less profound and far-reaching than those in the monsoon habitat as we see it in its typical development.” Saxton (Figure 4), like Dudgeon, recognizes significant seasonal changes in environmental conditions over a year: “… we often find that during the year two (or it may be three)

profoundly different sorts of conditions are met within the same spot. Practically, these constitute two (or three) entirely different habitats. First, a condition when both soil and air may be almost continuously water-saturated for about three months … [Second] at the close of the monsoon, the soil and air both gradually dry, and after about a month, a period of seven months of intense and absolute drought sets in.” The vegetation found during the rainy season (some kind of wetland) has nothing in common with that of the dry season (called xerophytic by Saxton) (Figures 4 and 5).

Out of hand, Saxton dismisses the idea that monsoonal habitats undergo some form of succession: “… this is not succession as understood in Oecology. Probably this will be universally admitted and it will not be necessary to discuss the point further.” After dismissing Dudgeon’s seasonal succession without referencing it, Saxton presents his new concept: mixed formations in time. “The theory is advanced that in such an area it often happens that we cannot regard

Figure

Saxton 1922).

a small and reasonably homogeneous part of it as occupied by a single unit (“formation”) of vegetation, but rather that two (or even three) entirely different plant communities regularly alternate with one another, though each persists to some extent through the dominant phases of the other, thus giving rise to the idea of “Mixed formations in time”.” In other words, Saxton proposes that monsoonal depressions have two or more phases (Figures 4 and 5). However, these seasonal phase shifts are not a form of succession because one phase does not give rise to or permanently replace another. For Saxton, the various phases are independent entities that exist simultaneously. While one phase is extant, the other(s) is(are) latent. The latter exist mainly as dormant seeds and vegetative propagules until environmental conditions change sufficiently. “Mixed formation in time” was not the aptest name for Saxton’s new concept, and his 1924 paper uses the more descriptive and intuitive “vegetation phases” in its title.

The seasonal shifts in vegetation in monsoonal depressions on the Gangetic Plain described by Dudgeon (1920) and Saxton (1924) are very similar. Dudgeon (1920) better describes the region’s monsoonal climate (Figure 2), whereas Saxton (1924) better describes and illustrates the vegetation phases (Figures 4 and 5). He also notes the importance of the seed bank and vegetative propagules for enabling species to persist from year to year in a wetland. The seed banks of monsoonal wetlands would not be studied for another 60 years (Middleton et al. 1991). In an attempt to determine what anatomical and morphological adaptations allow plant species to grow in a monsoonal area, a large part of Saxton (1924) is devoted to anatomical studies of selected plant species, a common type of ecological study that started in 19th Century Germany and persisted into the early 20th Century (van der Valk 2011, 2014).

DISCUSSION

The intra-annual vegetation phases of northern Indian monsoonal wetlands are an extreme example of comparable intra-annual cycles in wetlands in other parts of the world. Others include those found in seasonal prairie wetlands in North America (van der Valk and Mushet 2016), playa wetlands in North America (Bolen et al. 1989), and monsoonal wetlands in northern Australia (Finlayson 2005). Dudgeon was born in Mahaska County, Iowa, south of the Prairie Pothole region. Still, he studied botany at Iowa State College (now University) in Ames, Iowa, which is in the Prairie Pothole region. Much of the early work on the vegetation dynamics of prairie potholes was done in Iowa, much of it close to Ames (van der Valk 1981, 2005). Ironically, Dudgeon, while a student in Ames, could have observed similar, but less extreme, seasonal changes in pothole vegetation to those he later studied in north India. Dudgeon (1920) and Saxton (1922, 1924) described what was, for them, a new kind of wetlands that was

unknown to Western ecologists at the time. Although they studied the same wetlands, they differed in how they interpreted their intra-annual vegetation changes. Dudgeon described them as a new type of succession: “seasonal succession.” In contrast, Saxton described them as a new type of vegetation dynamic: “mixed formations in time” or “phases of vegetation.” From my perspective as someone who worked on the vegetation dynamics of monsoonal wetlands in northern India (Middleton et al. 1991, van der Valk and Middleton 2024), Saxton’s conceptualization of their vegetation dynamics as a series of vegetation phases better describes them than Dudgeon’s “seasonal succession.” However, it took 40 years for me to reach this conclusion (van der Valk and Middleton 2024). I made the mistake Saxton (1922) warned about when I began working in India in the 1980s. I interpreted the vegetation dynamics of monsoonal wetlands as a compressed habitat cycle, a type of cyclical succession found in semi-permanent prairie potholes in North America (Middleton 1999, van der Valk 1981, 2005). I studied habitat cycles in Iowa in the late 1970s and early 1980s. Habitat cycles are cyclical changes that occur over one to two decades (van der Valk 1981, 1982, 2005). In other words, I unconsciously adopted Dudgeon’s seasonal successional model in the guise of a compressed habitat cycle completed in only one year.

How much impact did Dudgeon and Saxton’s work have on the development of wetland science in India and elsewhere? Dudgeon (1920), according to Google Scholar, at the time of writing, has only been cited 36 times, mainly since the 1980s. However, Misra (1962), in a review paper on Indian vegetation studies, credits Dudgeon as the first ecologist to apply the concept of succession to Indian vegetation. However, Misra also faults Dudgeon for not taking a multiyear approach to the vegetation dynamics of monsoonal wetlands. Based on Misra’s studies of monsoonal wetlands (Misra 1946), the species composition of the vegetation of each climatically distinct part of a year (rainy, cool, hot) is very similar from year to year, e.g., the meadow vegetation in one year is very similar in composition to that in subsequent years. For Misra, no succession is occurring. Strangely, in his review paper, Misra does not cite Saxton’s papers. According to Google Scholar, Saxton (1922) has been cited only seven times, and Saxton (1924) 27 times. Saxton (1922) deserves to be recognized as a classic paper in wetland science. Its message — don’t let your past experiences close your eyes to a new reality — is as relevant today as it was in the 1920s.

After Dudgeon and Saxton, no scientific studies of monsoonal wetlands were conducted in India until the 1940s, when Ramdeo Misra (1908-1998) returned to India (Gopal 1986) after doing postgraduate research in England (Ph.D., 1937, Leeds) with the renowned t wetland ecologist W. H. Pearsall. On his return to India, Misra conducted ecological studies of northern India’s low-lying lands, ponds,

and herbaceous plant populations from 1937 to 1946 (Singh 2011). These studies (Misra 1946) confirmed much of what Dudgeon and Saxton had previously described but showed that the intra-annual vegetation changes found were more complicated than previously realized. Misra laid the foundations for field and experimental ecological studies at Indian academic and other organizations (Singh 2011). After Misra, no significant new studies of monsoonal wetlands were conducted in India until the 1980s.

Dudgeon and Saxton are important, if sadly littleknown and celebrated, figures in the history of wetland science. They contributed to wetland science in three significant ways. One, they made wetland science a genuinely international discipline by highlighting that there were wetland types not found in the West. Two, they pioneered the study of the impacts of water-level changes on wetlands, an important topic in contemporary wetland ecology. Three, they demonstrated that monsoonal vegetation is well adapted to large changes in water levels because propagule banks allow both wetland and upland plant species to survive either drawdowns or periods of flooding.

REFERENCES

Bharucha, F.R. 1975. Fifty years of ecological and phytosociological research in India. Vegetatio 30: 153-155. .jstor.org/stable/20036864

Bolen E.G., L.M. Smith, and H.L. Schramm. 1989. Playa lakes: prairie wetlands of the southern high plains. Bioscience 39: 615–623. doi. org/10.2307/1311091

Clements, F.E. 1916. Plant Succession: An Analysis of the Development of Vegetation. Carnegie Institution of Washington, Washington, DC. Cowles, H.C. 1911. The cause of vegetation cycles. Botanical Gazette 51: 161-183. doi.org/10.1086/330472

Dastur, R.H. and W.T. Saxton. 1922. The oecology of some plant communities in the savannah formation. Journal of Indian Botany 3: 34-51.

Dudgeon, W. 1920. A contribution to the ecology of the Upper Gangetic Plain. Journal of Indian Botany 1: 296-324.

Finlayson, C.M. 2005. Plant ecology of Australia’s tropical floodplain wetlands: a review. Annals of Botany 96: 541–555. doi.org/10.1093/aob/ mci209

Gopal, B. 1986. Vegetation dynamics in temporary and shallow freshwater habitats.

Aquatic Botany 23: 391-396. doi.org/10.1016/0304-3770(86)90088-4

Kenoyer, L.A. 1924. Plant life of British India. The Scientific Monthly 18: 48-65. jstor.org/stable/7150

Middleton, B.A. 1999. Succession and herbivory in monsoonal wetlands. Wetland Ecology and Management 6: 189–202. doi. org/10.1023/A:1008495121557

Middleton, B.A., A.G. van der Valk, D.H. Mason, R.L. Williams, and C.B. Davis. 1991. Vegetation dynamics and seed banks of a monsoonal wetland overgrown with Paspalum distichum in northern India. Aquatic Botany 40: 239-259.

Misra, R. 1946. A study in the ecology of low-lying lands. Indian Ecologist 1: 1–20.

Misra, R. 1962. The science of vegetation with reference to India. Bulletin of the Botanical Survey of India 4: 113-118.

Saxton, W.T. 1922. Mixed formations in time: a new concept in oecology. Journal of Indian Botany 3: 30-33.

Saxton, W.T. 1924. Phases of vegetation under monsoon conditions. Journal of Ecology 12: 1-38. doi.org/10.2307/2255545

Saxton, W.T. and L. Péringuey. 1917. Oncological notes on the district of Manubie, Transkei. Transactions of the Royal Society of South Africa 6: 37-44. doi.org/10.1080/00359191709520173

Singh, J.S. 2011. Ecology in India: Retrospect and Prospects. Bulletin of the National Institute of Ecology 22: 1-13.

Stewart, R.R. 1982. Missionaries and clergymen as botanists in India and Pakistan. Taxon 31: 57-64. doi.org/10.2307/1220590

van der Valk, A.G. 1981. Succession in wetlands: a Gleasonian approach. Ecology 62: 688–696. doi.org/10.2307/1937737

van der Valk, A.G. 1982. Succession in temperate North American wetlands. In B. Gopal, R.E Turner, R.G. Wetzel, and D.F. Whigham (eds.). Wetlands: Ecology and Management. National Institute of Ecology and International Scientific Publications, Jaipur, Rajasthan, India. pp. 169179.

van der Valk, A.G. 2005. Water-level fluctuations in North American prairie wetlands. Hydrobiologia 539: 171–188. doi.org/10.1007/s10750004-4866-3

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Advancing Lake Red Rock Reservoir Management Practices to Maximize Ecological Benefits: From Planning to Monitoring

Chuck Theiling1, Alyssa Calomeni1, Nicole Bosco2, Steve Dinsmore2, Hugh Howe3, Todd Gosselink4, Keith Schilling5, Matthew Streeter5, and Perry Thostenson3

INTRODUCTION

The Upper Midwest USA has highly developed agricultural landscapes with significant alterations to land cover and hydrology. Landscape conversion eliminated 89 percent of the wetlands and up to 99 percent in the shallow prairie pothole wetlands in Iowa (Bishop et al. 1998). Two flood control dams, Saylorville Lake and Lake Red Rock situated on the Des Moines River above and below Des Moines, Iowa, support extensive wetlands and are managed for multiple uses including flood risk management, low flow augmentation, fish and wildlife management, and recreation, and additionally for hydropower at Lake Red Rock. The Des Moines River reservoir tributary deltas are deemed “Important Bird Areas” by the National Audubon Society that cited its values of rare or unique habitats and significant species concentrations Waterbirds are consistently attracted to these reservoirs during fall migration when declining water levels expose vast mudflats that are colonized by annual plants (Vanausdall and Dinsmore 2021). This heterogeneous habitat is especially attractive to shorebirds (July through September) and waterfowl (August through November). In addition, river nitrate loads were reduced by 4.9 percent, on average, within Saylorville Lake reservoir, with greater nitrate loss occurring in low flow years with greater retention time compared to high flow years with rapid flushing (Stenback et al. 2014). Overall, water quality, wetland, and wildlife benefits occur during the regular, routine management of water levels to maintain the reservoir’s designated uses.

Recognition of the passive environmental benefits achieved in these Iowa reservoirs led US Army Corps of Engineers lake managers and stakeholders to consider actions to increase the ecosystem services derived from Des Moines River flood control dams, including decreasing nitrate concentrations and increasing wetland distribution and waterbird habitat benefits. A Sustainable Rivers Program (SRP) environmental flows workshop (Warner et al. 2014)

was held in 2016 to consider water management measures to increase ecosystem benefits derived from Saylorville Lake and Lake Red Rock. Where the SRP had previously focused primarily on downstream reservoir releases for riverine habitat improvements, the Des Moines River workshop also considered Environmental Pool Management (EPM) which was first implemented on the Mississippi River in 1994. EPM is the modification of reservoir and navigation pool water management to better mimic natural flows while remaining consistent with project authorizations.

The objective of this article is to describe the Des Moines River environmental flows evaluations and recommendations, their codification in new water control regulations, and to introduce the ecological benefits monitoring being conducted at Lake Red Rock.

LAKE RED ROCK

Lake Red Rock is a 6,171 ha (15,507 ac) reservoir formed following the completion of the Red Rock dam on the Des Moines River in 1969; it is the largest lake in Iowa. Flood management activities generally occur only 20 percent of the time during April to May which means water can be managed for environmental purposes the remainder of the year. The Lake Red Rock delta does not replace the dispersed small wetlands of the pre-settlement landscape (now lost), but it does provide approximately 2,800 ha (7,000 ac) of riverine delta habitat with extensive wetlands and mudflats. The “large manmade reservoir” wetland habitat class increased by ~4,000 ha (~10,000 ac) between 1980 to 1997 (Bishop et al. 1998), likely due to delta growth from sedimentation in Saylorville Lake and Lake Red Rock. There has not been any substantial reduction in sedimentation, so delta expansion continues (Figure 1) which is typical of many US reservoirs.

Prior environmental considerations for Lake Red Rock water management were limited to conservation pool maintenance, low flow releases, and a 0.6 m (2 ft) fall reservoir rise to support migratory waterfowl and hunter access to the delta region. In 2018, several environmental and operational needs necessitated a review of the Des Moines River Basin Master Reservoir Regulation Manual (RRM). Key indicators of a need for modifications to the RRM were: 1) significant increases in the magnitude and frequency of flooding events, 2) sedimentation rates within Saylorville Lake, and 3) the need to codify environmental deviations in water-control plans (i.e., EPM) approved from 2016 to 2018 (USACE Rock Island District 2019).

1 US Army Corps of Engineers, Engineer Research and Development Center, Vicksburg, MS, Corresponding author contact: Charles.h.theilng@usace.army.mil

2 Iowa State University, Ames, IA

3 Lake Red Rock, Knoxville, IA

4 Iowa Department of Natural Resources, Knoxville, IA ,

5 University of Iowa, Iowa City, IA

ENVIRONMENTAL FLOWS WORKSHOP

Opportunities to adapt dam operations for increased environmental benefits at Des Moines River flood risk management projects were explored in 2016 using the SRP environmental-flows assessment process developed by USACE and The Nature Conservancy (Warner et al. 2014). This process incorporates collaboration workshops to identify water-management recommendations using stakeholder input from federal (i.e., USACE and U.S. Fish and Wildlife Service), state (e.g., Iowa Department of Natural Resources), and local agencies (e.g., Polk County Conservation), a nongovernmental organization (i.e., TNC), and academic institutions (i.e., University of Iowa and Iowa State University). Environmental flow requirements for specific taxonomic groups (for example, waterbirds, reptiles, fish), wetland habitats, and water quality were key components of reservoir management alterations.

Lake Red Rock environmental flow recommendations (i.e., targeted elevations, durations, and timing) were based on expert hypotheses regarding water level management to positively impact environmental outcomes (Warner et al. 2014). Workshop topics included nitrate concentrations, conditions needed for waterbird migration, and habitat for reptiles. EPM considerations are anticipated to drive the water plan during 80% of a typical operating year. Water levels are held higher in the spring to support fish spawning, they are slowly lowered during summer to promote wetland expansion, they are raised higher during fall waterfowl migration, and held high through winter to support reptile overwintering (Figure 2). The water management plan differs for wet, average, and dry years in anticipation of variable annual hydrology.

Figure 1. Lake Red Rock delta expansion due to sedimentation from 1990–2021 (Source: Todd Gosselink, Iowa Department of Natural Resources)

Figure 2. Lake Red Rock environmental pool management plan for a year.

ENVIRONMENTAL BENEFITS MONITORING

Environmental benefits of EPM are being monitored by several researchers. Interdisciplinary research is necessary to consider the full range of environmental effects on water, sediment, plants, and animals for which lake levels can be adaptively managed to optimize outcomes (Figure 3). Ongoing and future monitoring efforts include an assessment of historical reservoir nitrate biogeochemistry data and literature review to document declines in nitrate concentrations prior to implementation of the new EPM plan (Schilling et al. 2023). A delta geomorphic assessment with topographic delineation, sediment mapping, and denitrification analyses to characterize inundation patterns in the delta is underway. Surface water-quality (i.e., temperature, specific conductivity, pH, and dissolved oxygen concentra-

tion) and nitrate concentrations will be evaluated using a boat-mounted spatial analysis system to map water quality conditions throughout the delta (Meulemans et al. 2020). Wetland, waterbird, and macroinvertebrate monitoring are ongoing to quantify these environmental benefits. Reptile overwintering monitoring is using remote radio transmitters deployed at Lake Red Rock.

Geomorphology and Water Quality

The data and literature review included 42 years of longterm upstream and downstream nitrate monitoring records. Lake Red Rock removed approximately 7,000 Mg nitrate per year, representing 12.4% of the nitrate inputs to the reservoir. Estimated annual nitrate removal rates varied considerably based on flow. This study supports that during periods of high nitrate concentrations and loads, reservoir water levels could be manipulated to achieve longer water

Figure 3. Lake Red Rock environmental benefit assessment questions.

retention times achieving greater nitrate removal rates (Schilling et al. 2023).

Lake Red Rock has lost substantial volume over time due to delta progradation which encroached 2.5 miles into the lake between 1994 to 2021 as estimated from National Agricultural Imagery Program imagery (see Figure 2). Sediment physical and chemical characteristics can impact the rate of removal of nitrate within aquatic systems. Field observations identified substantial variation and layering in the delta alluvium related to historical floods that influence surface and hyporheic flow throughout the delta sediment. Altogether, the geomorphic mapping, sedimentology, and nutrient processing rates will be used to further refine models that can predict nitrate removal for water operations within Lake Red Rock. Monthly boat surveys of nitrate concentrations in the reservoir are being conducted to understand how surface water nitrate concentrations are

impacted by seasonal connectivity,

Wetlands

EPM exposes mudflats, promotes vegetation growth, and allows it to seed (Figure 4). These wetland areas serve as an important wildlife food source and provide habitat for migratory waterbirds during fall migration. One objective of wetland vegetation monitoring is to measure vegetation responses (e.g., species diversity and cover) to lower water levels in late summer. Another objective is to link vegetation responses with wildlife benefits.

Vegetation monitoring conducted during summer 2021 and 2022 quantified plant species, diversity, and cover. As water levels dropped and exposed mudflats, approximately two weeks were needed for vegetation to be observed. Within slightly more than a month, 100% vegetation cover

Figure 4. Lake Red Rock delta habitat progression July to September 2021.

was observed. Across both survey years, 19 plant species were identified and included important wildlife foods (Table 1). Thirteen plant species within the mudflat area came to seed and this typically occurred within a month. Vegetation growth slowed in late August indicating that EPM drawdowns should begin in July to ensure a 30-day window for plants to come to seed.

Waterbirds

The Des Moines River corridor, which meanders through the Prairie Pothole Region (PPR) of Iowa, is a major migratory corridor for waterbirds. In particular, the region hosts millions of migratory waterfowl and shorebirds, two groups of birds that are the focus of many management and conservation efforts. Wetlands with diverse habitat conditions (e.g., differing water depths and healthy aquatic plant communities) are critical stopover sites for migratory waterbirds to refuel for the next step in migration. Identifying these stopover sites and understanding how individuals use a site, are critical for future conservation and management efforts (Vanausdall and Dinsmore 2021). Bird use of Lake Red Rock stopover sites is being evaluated by regular visual surveys of the site during fall migration.

A total of 49 waterbird species were documented in 2021 and 44 in 2022 (Table 2). The most prominent subgroups identified included shorebirds (27 spp.) and waterfowl (9 spp.); and all other waterbird groups totaled 14 species (e.g., gulls, terns, and pelicans). On average there were 30 and 26 species recorded per visit in 2021 and 2022, respectively, with species diversity peaking during late August and early September. There were >335,600 individuals counted across all surveys during the fall 2021 and 2022 migration period. American White Pelican (Pelecanus erythrorhynchos) was the most numerous species (approxi-

Scientific name

Common name

Echinochloa crus-galli Barnyardgrass

Xanthium strumarium Rough cocklebur

Phalaris arundinacea Reed canarygrass

Leersia oryzoides Rice cutgrass

Cyperus spp. Flatsedges

Amaranthus palmeri Palmer’s amaranth

Ammania coccinea Scarlet toothcup

Lindernia dubia Yellowseed false pimpernel

Polygonum pensylvanicum Pennsylvania smartweed

Sagittaria latifolia Broadleaf arrowhead

Bidens cernua Nodding beggartics

Mimulus ringens Allegheny monkeyflower

Bidens frondosa Devil’s beggarticks

Sinapis arvensis Wild mustard

Phyla lanceolata Lanceleaf fogfruit

Rorippa palustris Bog yellowcress

Salix spp. Willows

Acer saccharinum Silver maple

Populus deltoides Eastern cottonwood

mately 40%), Pectoral Sandpiper (Calidris melanotos) was the most abundant shorebird species (12% in 2021 and 17% in 2022) followed by the Least Sandpiper (Calidris minutilla) (Table 2). The most abundant waterfowl species observed were the Blue (Spatula discors) and Greenwinged teal (Anas carolinensis). Unusual species included

spp.; ~175,000 ind.

spp.; ~160,300 ind.

(3%)

Table 1. Plant species found on the Lake Red Rock delta in 2021 and 2022.

Table 2. Lake Red Rock waterbird survey results listing the six most numerous species in each year.

Piping Plover (Charadrius melodus), Red Knot (Calidris canutus), Ruddy Turnstone (Arenaria interpres), Marbled Godwit (Limosa feoa), Western Sandpiper (Calidris mauri), Common Gallinule (Gallinula galeata) and other species of greatest conservation need (Table 3).

Least Sandpiper Telemetry

Radio telemetry studies of Least Sandpipers were conducted in 2021 and 2022 to estimate residency times and characterize site use for this species (Figure 5). A total of sixty (2021) and eighty (2022) transmitters were deployed on Least Sandpipers between July and August, there were 106 adults and 34 juveniles. The last resight of a tagged individual was on September 13, 2021 and September 1, 2022. This provides evidence for when water management can shift from shorebird to waterfowl management which raises fall water levels to allow access to wetland plant foods to feed migrating waterfowl.

DISCUSSION AND CONCLUSIONS

Lake Red Rock EPM began with experimental water level management in 2016 to 2018 and will continue for the foreseeable future under the new water regulation plan. The EPM adaptive management is suited for a range of flows and operated through a drought in 2022 with excellent outcomes and suitable flow to inundate the delta for fall migrating waterfowl and hunters. The practice is applicable to a subset of dams with specific operating conditions. Neipert et al. (2023) designed an approach for a nationwide, ecoregion spatial analysis of USACE Flood Risk Management dams suitable for EPM. Completing the tool would support a rapid identification and prioritization of projects that can benefit from EPM. It would also support developing regional avian management plans (Jung et al. 2022, Neipert et al. 2023).

Lake Red Rock research is demonstrating that EPM is a cost-effective management practice. Typical costs for large Corps of Engineers restoration construction projects such as island building, river wetland enhancement, backwater dredging coupled with forest plantings, and combinations of features on projects up to 1,000 ha in size on the Upper Mississippi River range from $2,000 - $5,000/ average annual habitat unit (AAHU). Pool scale water level management can improve habitat over thousands of ha and is much more cost-effective at <$1,000/AAHU or much lower for most Upper Mississippi River dams (WLM Regional Coordinating Committee 2022). Pre-project dredging is the only construction activity required, and many only need to be done once to support multiple drawdown events. Water level adjustments are daily operations at most dams and the mode of operating EPM requires the same level of effort but delivers greater environmental benefits that will be documented by our research. The environmental flows planning and implementation also created social benefits by forming the collaboration teams that have

periods.

Federal Threatened State Endangered Piping Plover Piping Plover

Red Knot

Species of Greatest Conservation Need

Blue-winged Teal White-rumped Sandpiper

American Wigeon Buff-breasted Sandpiper

Northern Pintail Pectoral Sandpipier

Redhead Semipalmated sandpiper

Common Gallinule Short-billed Dowitcher

Black-bellied Plover Lesser Yellowlegs

American Golden Plover Wilson’s Phalarope

Hudsonian Godwit Franklin’s Gull

Marbled Godwit Black Tern

Ruddy Turnstone Forster’s Tern

Sanderling American white Pelican

worked together for several years of shared planning and field work that will continue for the foreseeable future.

ACKNOWLEDGEMENTS

Wetland and waterbird, delta elevation characterization, and historic denitrification research was funded by USACE Sustainable Rivers Program.

REFERENCES

Bishop, R.A., J. Joens, and J. Zohrer. 1998. Iowa’s wetlands, present and future with a focus on Prairie potholes. Journal of the Iowa Academy of Science 105: 89-93. Available from https://scholarworks.uni.edu/jias/ vol105/iss3/3

Jung, J.F., R.A. Fischer, C. McConnell, and P. Bates. 2022. The Use of US Army Corps of Engineers Reservoirs as Stopover Sites for the Aransas-Wood Buffalo Population of Whooping Crane. Technical Report ERDC/EL TR-22-8. US Army Corps of Engineers, Engineer Research and Development Center Environmental Laboratory, Vicksburg, MS 30pp. Available from https://apps.dtic.mil/sti/pdfs/AD1176388.pdf

Table 3. Lake Red Rock bird species of conservation need observed during 2021 and 2022 monitoring

Figure 5. Least sandpiper telemetry.

Meulemans, M.J., C.S. Jones, K.E. Schilling, N.C. Young, and L.J. Weber. 2020. Assessment of spatial nitrate patterns in an Eastern Iowa watershed using boat-deployed sensors. Water 12: 146. https://doi. org/10.3390/w12010146

Neipert, E.S., T.E. Steissberg, and C. Theiling. 2023. Spatial Screening for Environmental Pool Management Opportunities. Technical Report ERDC/EL TR-23-9. US Army Corps of Engineers, Engineer Research and Development Center Environmental Laboratory, Vicksburg, MS. Schilling, K.E., E. Anderson, M.T. Streeter, and C. Theiling. 2023. Long-term nitrate-nitrogen reductions in a large flood control reservoir. Journal of Hydrology 620: 129533. https://doi.org/10.1016/j.jhydrol.2023.129533

Stenback, G.A., W.G. Crumpton, and K.E. Schilling. 2014. Nitrate loss in Saylorville Lake Reservoir in Iowa. Journal of Hydrology 513: 1-6. https://doi.org/10.1016/j.jhydrol.2014.03.037

US Army Corps of Engineers – Rock Island District (USACE Rock Island District). 2019. Des Moines River Master Reservoir Regulation Manual Feasibility Report with Integrated Environmental Assessment. U.S. Army Corps of Engineers, Rock Island District, Rock Island, IL. 107 pp. Available from https://hdl.handle.net/11681/39939

Vanausdall, R.A., and S.J. Dinsmore. 2021. Stopover ecology of the least sandpiper (Calidrilis minutilla) in Iowa: Implications for reservoir management. Lake and Reservoir Management 37: 300-312. https://doi. org/10.1080/10402381.2021.1920071

Warner, A.T., L.B. Bach, and J.T. Hickey. 2014. Restoring environmental flows through adaptive reservoir management: planning, science, and implementation through the Sustainable Rivers Project. Hydrological Sciences Journal 59: 3-4, 770-785.https://doi.org/10.1080/02626667.20 13.843777

WLM Regional Coordinating Committee. 2022. Water Level Management Opportunities for Ecosystem Restoration on the Upper Mississippi River and Illinois Waterway: An update to the NESP Environmental Report 53. Upper Mississippi River Basin Association, Bloomington, MN. 40 pp. Available from https://umrba.org/sites/default/files/documents/Water%20Level%20Management%20Opportunities%20for%20 Ecosystem%20Restoration%20on%20the%20UMRS%20-%20July%20 2022.pdf