Bulletin BULLETIN of the ILLINOIS NATURAL HISTORY SURVEY HARLOW B. MILLS, Chief Effect of Permanent Flooding in a River-Bottom Timber Ares LEE E. YEAGER Printed by Authority of the STATE OF ILLINOIS ADLAI E. STEVENSON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION NOBLE J. PUFFER, Dirtcfor S T A T E OF ILLINOIS Adi.ai E. Stevenson, Governor BEPARTMENT OF REGISTRATION AND EDUCATION Noble J. Puffer, Director NATURAL HISTORY S U R \' E Y DIVISION Harlow B. Mills. Chief Volume 25 BULLETIN Article 2 Effea of Permanent Flooding in a River-Bottom Timber Area LEE E. YEAGER Printed by Aulhority of thr State of Illinois URBANA, ILLINOIS August 1949 STATE OF ILLINOIS Adlai E. Stevenson, Governor DEPARTMENT OF REGISTRATION AND EDUCATION Noble J. Puffer, Director A. E. Emerson, Ph.D., Biology L. H. Tiffany, Ph.D., Forestry L R. HowsoN, B.S.C.E., C.E., Engineering BOARD OF NATURAL RESOURCES AND CONSERVATION Noble J. Puffer, Chairman George D. Stoddard, Ph.D., Litt.D., L.H.D LL.D., President of the University oj Illino Walter H. Newhouse, Ph.D., Geology Roger Adams, Ph.D., D.Sc, Chemistry NATURAL HISTORY SURVEY DIVISION Urbana, Illinois Scientific and Technical Staff Harlow B. Mills, Ph.D., Chief Bessie B. Henderson, M.S., Assistant to the Chief Section of Economic Entomology George C. Decker, Ph.D., Entomologist and Head J. H. Bigger, M.S., Entomologist L. L. English, Ph.D., Entomologist C. J. Weinman, Ph.D., Entomologist S. C. Chandler, B.S., Associate Entomologist Willis N. Bruce, M.A., Assistant Entomologist John M. Wright, M.A., Assistant Entomologist H. B. Petty, M.A., Associate in Entomology Extension Section of Faunistic Surveys and Insect Identification H. H. Ross, Ph.D., Systematic Entomologist and Head Milton W. Sanderson, Ph.D., Associate Tax- onomist Lewis J. Stannard, Jr., M.S., Assistant Tax- onomist Leonora K. Gloyd, M.S., Laboratory Assistant Philip W. Smith, B.S., Laboratory Assistant Technical Library Marguerite Si.mmons, M.A., M.S., Technical Librarian Section of Publications and Public Rela- tions Ja.mes S. Ayars, B.S., Technical Editor and Head Blanche P. Young, B.A., Assistant Technical Editor Charles L. Scott, B.S., Assistant Technical Photographer Section of Forestry Willet N. Wandell, M.F., Forester and Head Lawson B. Culver, B.S., Associate in Forestry Extension Robert K. Stubbs, B.S., Research Assistant Section of Applied Botany and Plant Pa thology Leo R. Tehon, Ph.D., Botanist and Head J. Cedric Carter, Ph.D., Plant Pathologist J. L. FoRSBERG, M.S., Associate Plant Pathoh gist G. H. Boewe, M.S., Assistant Plant Pathologi Robert A. Evers, M.S., Assistant Botanist Joan H. Laube, B.S., B.M., Technical Assista' Section of Game Research and Manage ment Ralph E. Yeatter, Ph.D., Gaine Specialist Frank C. Bellrose, B.S., Associate Game .?/>. cialist Harold C. Hanson, M.S., Assistant Game Sp, cialist James S. Jordan, M.F., Assistant Game Tect nician William Nuess, Laboratory Assistant Cooperative Wildlife Research (Lllinois Department of Conservation and V.. Fish and Wildlife Service, Cooperating) Paul J. Moore, B.S., Project Leader George C. Arthur, B.S., Project Leader Lysle R. Pietsch, M.F., Project Leader John C. Calhoun, B.S., Assistant Proje- Leader William J. Harth, M.S., Project Leader Section of Aquatic Biology George W. Bennett, Ph.D., Aquatic Biologi. and Head William C. Starrett, Ph.D., Associate Aqua, ic Biologist D. F. Hansen, Ph.D., Assistant Aquatic B> ologist R. Weldon Larimore, M.S., Research Assisi ant Daniel Avery, Field Assistant Consultant in Herpetology: Hobart M. Smith, Ph.D., Assistant Professor of Zoology, University o Illinois, This paper is a contributionfrom the Section of Forestry- (77567—4M—4-49) CONTENTS Acknowledgments 33 \rea Studied 34 ?TUDV Procedure 35 FiMBER Types 37 A'ater Levels 39 Free Mortality 41 Trees Standing in Water 41 Trees Standing in Mud 43 Trees Standing on Land 46 Discussion 47 Pree Fall 51 Rate and Manner of Falling 51 Fate of Fallen Trees 52 ^ost-Floodixg Succession 54 Plants 54 I A'lammals 57 Birds 61 UMMARV 63 ITERATURE Cited 65 .>,^i^ '^^tei4*^.'- " J5 -a .s o -a o c Bji U Effect of Permanent Flooding in a River-Bottom Timber Area LEE E. YEAGER* WATER impoundments, varying from simple fish ponds to the vast programs now being spon- sored by the United States Corps of En- gineers and the Bureau of Reclamation, in- vohe many changes in the American land- scape. Practically every major stream and hundreds of smaller ones ha\e been or, if present proposals are consummated, will be affected by dams erected for power de- velopment, channel improvement, flood and erosion control, and other purposes. The environmental eftects inherent in this nation-wide program are potentially of great importance to wildlife, inland fisher- ies, bottomland forests, and agriculture. One of the problems associated with stream damming and resultant impound- ments is that of flooded timberland. On many projects, especially where public funds are involved, the areas to be flooded are cleared of trees and brush. On others, clearing may be done only partly or not at all, because of shortage of funds, or because of bad weather, high water, or other reasons. Flood-killed timber is gen- erally considered by the public as un- sightly, and complaints concerning it may be strong. Dead trees that reach navigable streams after falling offer certain hazards to shipping, commercial fisliing, and other enterprises associated with inland waterways. Therefore, whether from the standpoint of aesthetics or economics, flood-killed timber is a problem, and one * Formerly Forester, Illinois Natural History Survey, Urbana, Illinois. Since May, 1945, with the United States Fisli and Wildlife Service; present station, l.c.idcr. Colo- rado Co-operative Wildlife Research Unit, Colorado Agri- cultural and Meclianical College. Fort Collins. Colorado. The major portion of the investigation on which the present paper is based was made while lh« author was employed by the Natural History Survey. Completion of the study was accomplished through a co-operative arrangement between the Survey and the Fish and Wild- life Service, having a strong probability of increasing in importance. The objective of the study on whicii the present report is based was to deter- mine the rate of flooding mortality in var- ious Mississippi River \alley tree species and the rate and effect of tree fall ; in the course of the stud\ , brief consideration was given to plant and animal succession following the death of timber stands. The report covers principally the period begin- ning in September, 1939, and ending in October, 1946. ACKNOWLEDGMENTS My obligations for assistance during this investigation are many. 1 am indebted, first of all, to the late Dr. Theodore H. Frison, former Chief of the Illinois Nat- ural History Survey, who proposed the study. To Dr. Leo R. Tehon, during part of the study period. Acting Chief of the Natural History Survey, and to Dr. Gustav A. Swanson, formerly with the Fish and Wildlife Service, I owe thanks for the co-operative arrangement wherein I was permitted to complete field obser- vations. Dr. Tehon aided in planning the in\estigation and Mr. G. H. Boewe, also of the Survey staff, assisted with initial field work. Dr. Cornelius H. MuUer, while with the Natural History Survey as a botanist, made the detailed vegetation map on whicli later work was based. For data used in preparing fig. 5, I am in- debted to the St. Louis District, Corps of Engineers, Department of the Army, Sev- eral wildlife specialists of the Natural History Survey or co-operating organiza- tions gave valuable help: Mr. Charles S, Spooner, Jr., was of much assistance in mapping; Mr. Frank C, Bellrose, Dr. [33] 34 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 Ralph E. Yeatter, Mr. Harry G. Ander- son, Mr. Charles McGraw, and Mr. Wil- let N. Wandell provided numerous rec- ords and were helpful in other ways; and Mr. Robert G. Rennels made careful anal- \sis of food-habits material. Mr. Carl Pohlman, a resident of Calhoun County, gathered valuable records on the fur take. Mr. James S. Ayars, Mr. Robert E. Hes- selschwerdt, and Dr. H. H. Ross, editor, photographer, and systematic entomolo- gist, respectively, of the Illinois Natural History Survey, are responsible for most of the photographs used here as illustra- tions. Mr. Ayars' assistance with editorial problems is gratefully acknowledged. AREA STUDIED Detailed work forming the background for the present report was done on the Pere Marquette Wildlife Experimental Area, locally known as Calhoun Point, in Calhoun County, Illinois, fig. 1. Calhoun ILLINOIS STATE NATURAL HISTORY SURVEY Point was formed by the confluence of thf Mississippi and Illinois rivers. At other than flood periods, previous to 1938, the 2,200-acre Pere MarquetU area, roughly 1 by 4 miles, was character- ized by numerous wooded ridges, flats and wet-weather sloughs, several small lakes, a number of small marshes, and the margins of two large rivers. In June, 1938, gates of the recently completed Al- ton Dam, 20 miles downstream on the; Mississippi River, were closed for the first time. This closure resulted in flooding sev- eral hundred acres of the area, normally land. Although the gates were opened a few times after June, 1938, the higher than normal water level that prevailed through much of the 1938 growing sea- son, fig. 5, was sufficient to affect plant species sensitive to flooding. By the summer of 1939, 600 acres (27 per cent) of the area were permanently inundated; 1,600 acres (73 per cent) lay above pool level, which was 15.3 feet PERE MARQUETTE WILDLIFE EXPERIMENTAL AREA AND MIGRATORY WATERFOWL REFUGE Fig. 1.—Air view of Calhoun Point, Calhoun County, Illinois, May 1938, prior to flooding. Aimust, 1949 Yeager: Effeit of Permanent Flooding 35 at Grattdii, 2 miles downstream. Prior to the Alton impoundment, annual fluctua- tion of the Mississippi and Illinois rivers in the locality varied from subgage lows to floods exceeding 25 feet. Even after the impoundment, severe floods occurred in 1043 and 1^44 and a lesser flood in 1945. Permanent flooding increased the average summer water stage by about 3 feet. Ma.\- imum ele\ation on the area before im- poundment was 10 feet; at pool level, after impoundment, the highest ridges were only 7 feet above the water surface. These figures indicate the very low relief of the Pere Marquette area. STUDY PROCEDURE Kasic to the work reported here \\as a detailed vegetation map of the area prepared by Cornelius H. Muller while with the Natural History Survey's Sec- tion of Applied Botany and Plant Pa- thology. Muller did his field work between February 8 and June 11, 1938, shortly before initial flooding of the area was begun. In mapping the area, he estab- lished 1 1 transects, each 50 feet wide, that \aried in length from 600 feet to 1.1 miles and totaled 5.9 miles. Muller established the transects after he had made a general reconnaissance map of the many minor vegetation t>pes distinguishable. He did not space the transects uniformly or orient them parallel with each other, but laid them out to cross as many as possible of the water channels and sloughs then present on the area and to traverse in a representative way as many as possible of the vegetation types. He mapped the transects in such detail as to show the location of all trees, all large shrubs, and most of the herbaceous plant areas within them, recording species (substantiated by specimens deposited in the Illinois Natural History Survey her- barium), diameters of trees, sizes of shrubs, and density of herbaceous cover. The location of si.x transects, 1,2, 6, 7. 8, and 11. totaling 3.5 miles, is shown in fig. 2. These transects constitute the sample used as a basis for the present paper. Active field work on the effect of flood- ing was begun in September, 1939, about 3 months after the date of permanent in- undation. (The Alton Dam had been closed during the summer and a part of the fall of 1938, fig. 5.) The first rec- ords taken by the writer were before any of the trees had died, although the pin oaks and a few trees of other species showed effects of an abnormally high water stage. In the six sample transects, 1, 2, 6, 7, 8, and 11, each living tree and shrub, re- gardless of species, size, or condition, was tagged for future inspection, except «in pure stands of maple or elm on land, or in large clumps of waterprivet or but- tonbush in water, where only every sec- ond, third, or fifth tree or shrub was tagged. Markers or tags were of 14-gage galvanized sheet metal, about 1 by 2 inches in size, each perforated at one end, and numbered consecutively. Attachment was by means of sixpenny galvanized nails, at a height of about 4.5 feet. In each transect the tags faced one direction, always that opposite to the direction of progress, thus facilitating both attachment and relocation. Transects were marked at each end and at \ arying intervals by ap- propriately numbered signs. Records made at the time tags were at- tached and at all succeeding inspections were kept on the same form. At the first inspection, made when tags were at- tached, the number was recorded for each tree, and with it the tree species, d.b.h., cro\\'n class, and general vigor as near as this could be estimated. Where water oc- curred, the depth at the base of each tagged tree was recorded. At each suc- ceeding inspection, the condition of the tree and the water depth, which varied as shown in fig. 5, were the main records t iken. Trees obviously dying, but still with green lea\ es or cambium, were so recorded. Observations were made in June and October, 1940; one record was taken in June, 1941, one in October, 1942. and another in October, 1944, table 2. 'The final record was taken in October, 1946. A total of six inspections, in addition to those at the time of tagging and on numerous visits at other seasons, supplied data for this report. Supplementing the detailed investiga- tion in the Pere Marquette area were ob- servations made in flooded areas along the 36 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 PERE MARQUETTE WILDLIFE EXPERIMENTAL AREA GRAFTON. ILLINOIS Fig. 2.—Land and water areas on the Pare Marquette Wildlife Experimental Area, Calhoun Point. Orientation of the six transects supplying sample data is shown by straight, heavy lines. The direction of flow of the Illinois and Mississippi rivers in this area is approximately north-, east. Mississippi River in Jo Daviess, Hender- son, and Pike counties, and along the Illi- nois River in Mason and Jersey counties, all in Illinois. These areas were similar to Calhoun Point except that they were nar- rower, were bordered by large rivers along only one side, and supported greater pro- portions of willows and cottonwoods in the stands. The supplementary observa- tions, confirmatory in nature, are not in- corporated in this report. Common and scientific nomenclature in this paper is, in most instances, based on the following authorities: Kelsey & Day- ton (1942) for plants; Necker & Hat- field ( 1941 ) for mammals ; American Or- nithologists' Union (1931) for birds. Some forms were not identified to species. August, 1949 Yeager: Effect of Permanent Flooding 37 TIMBER TYPES Most of Calhoun Point, at the time of permanent flooding, was co\'ered by river- bottom forest characteristic of that found in the upper Mississippi River valley. The stands, varying from sapling to ma- ture growth, contained scores of very large, decadent, and often dying silver maples, with an occasional elm, sycamore, and pin oak of similar type, fig. 3. Com- position, size classes, and the scientific names of all important trees and shrubs contained in the samples are indicated in table 1. Silver or soft maple was the most abundant of the large trees in the flooded area. On the lowest level on which trees grew, it easih' dominated all plants ex- cept semiaquatic species, such as black willow, buttonbush, waterprivet, and waterlocust, tig. 4. Many of the maple 1 i;;. J. Il.,^>, . . . : :ii,i:,.: L, and characteristically mullihi ancheil maples, elms, oaks, and sycamores were found in the Calhoun Point stands, October, 1940. 38 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 o U B 3 O J3 "a u ^"'^-'.L IIV -^ CN 1— pnpM pnjM |-~-tN(NOOOOOOOOOOOOOOOOOOOOO ,,,r,.. lr~-OcT*-"0Or^O0O(NO00-*0000O00O pnp\[ (NOOl-^OOOOOOOOOOO— oooooooo puBq 0-^OroO^'^'^'^00000--<000000 P"PM -^0^-^c--)CSOroO^^^-'00000000000000 puEq aajB,^ P"W pUE"^ jsjejVV in .— t^ooOO^r^>J^(NtnT^^-.OO^HO^HOOOOOOO pn^M Oioij-iOOcO-^.-'OrlO-^OOOOOOOOOOOO PUE^J 0\CS'.-^CStN^^C^'-0OO^H^-\0OOC0^H.— jajEj^ oocsoocsoooo—'ooo^or-ooooooo pnjM puEq -hO-hOO(NOOOOO—'0000.-HOOOOOOO OO—'OOOO—ths ab()\'e the root collar died in 1 to 6 years. Shown above is a watcrprivct, relatively resistant to flooding, that died during the fourth year when Hooded 20 inches. The large tree is a persimmon, which died during the second year. A heavy mat of duckweed covered the water in this area. The writer, taking notes, October, 1941. 42 Illinois Natural History Survey Bulletin Vol. 25, Art. 00 August. 1949 Yeacer: Effect of Permanent Flooding 43 Fig. I.— Diameter of tree or shrub had little effect on survival after Hooding except in serai- aquatic species and in reproduction sizes. In the area pictured above, all trees of 3 to 30 inches (larger trees in background) had succumbed by October, 1946, in 8 years of permanent flooding. buttonbush, willow, and, to a less degree, waterprivet appeared to be adapted to conditions induced by impounded waters. Buttonbush did not succumb except where completely, or nearly, inundated. The few ash trees still living in October, 1946, were obviously dying. Trees and shrubs of the various di- ameter classes showed little differentiation in survival ability after flooding except in the 2-inch class, table 3. In this class the difference was due to species (water- privet and buttonbush, both semiaquatic) rather than to size, fig. 7. In general, healthy, vigorous trees of each species showed the greatest resistance to flooding, and the very small and the overmature classes of each species showed the least resistance. Trees and shrubs still living and vigor- ous in 1944 were, in all cases, on the less deeply flooded areas ; only waterprivet, buttonbush, and black-willow shrubs or trees still survived in water over 20 inches deep, table 4. More than half of the waterprivets and willows were dead by October, 1946. Before 1938, willows grew naturall\' in water or on the banks of sloughs and were flooded to greater depths than any other tree species ; the depth averaged approximately 3 feet on the lower (northern) end of Calhoun Point. Had willows occurred in position to sustain all depths of inundation, a higher percentage of survival probabl\ would have resulted. To all but seini- aquatic species, permanent flooding to a depth of 20 inches or less above the root collar was fatal. Trees Standing in Mud Trees in mud, in coinparison with trees standing in water, showed a more or less 44 Illinois Natural History Survey Bulletin Vol. 25, Art. -a s E T3 O O 1^ |2 3 O i- o H CJ o T pcaa PESQ S33JJ^ JO jaquinj^ puaa 4U33 J3J PE3Q aaqtunjvj S33JJ^JO jaqiunf^ 3USD -"^d 43quin[,j S33JJL JO J3qiunf>j JU33 JSJ PE3Q Jsquinjsj ssajj^ JO jsqtunfyj P«3a JU33 J3J PESQ J3quin|vj S33JJ_ JO J3qtunj\[ PESQ ;u33 jsj pE3a J3qLunj\i S33JJ^ JO jsqiunivi PE3a }U33 J3J pE3a jsqmnfj S33JX JO jsqiunjsj PESQ JU33 J3J pE3a J3qiunf>j oooooooooo>nooooo oo o o o d o o o oo o o o o o o I 18 18 I I oo U-l CS ON <— I I I I I I I II oovncNON-—lOOOOOO-—'O"^©© r- ^ rf ^ ro cN <*' "I II III I II r^OCT* — OOrOOOOtNO-*00 oo!-ooo oo oo o d> cimdi<6 I dd I iddi i loooc^oolool loo I I lo oo ^ .— , CO ^ I I I I I ooorom^O^-'-^OO^^'^OOO^-' 1 O O O O O O O c IdnDod I do dc ) OQO o o I o ov o c I I I < Tt- Tf Tjl O O O ^ > o ^ o o o o o ) o r- o o o o o 3 O CO O O O O O o ^ o O CO oorn o ro "^ r-- •—' rn - I I r^uooo.—lO--''sfc'^or^co-^OOOO > O "^ ) o o oo O O O ^^ O O O ON o o o o o o o o o o oO »J^ o o I I 1 W-) CS 1—« .— I .-< I I 1—l0^ooOO^r^'ocS•^^-H.-•0'—'O I 18 I IS I i I I o I "^ I o I F^ 1 I I- I I I I I I I S33JJ_ JO jaqiunjSj oocNoocNOOoo^HO-^or-'-o r< S'S- F .£3 > a o OJ J^ ^ O -C " rt rt -^ t 3 %3^ August, 1949 Yeaoer: Effect of Permanent Flooding 45 «> •a o 01 c O u PBSQ 1U33 J3J ;ooci"->oooco JsquitijVi S33JX JO jaquinjy: praa JU3D -isd PESQ jaqmnjj S33JJ^ JO Jaquin^vj jua3 J3J 00 00 000 8 l§ I 18 18 I 1888 I I I o) ,-, ^t* ^o 01 >c I 11- I M M *OtNOO — O-*OO^C~*• — — — • eOvOCS^Cror-CSOOC-or4-^CS'—0^- OOf^OOf-^OOOOcoOnOOO O0"-i00r->000000000 dc^dbrod»^dbbbddbOC"^OOt^CI^OC' O CO pEag jaqmnjij; S33JJL JO jaqmnjvj — w > o = C c •r ^ u t i- fe. c o S c — 1)^:0 H 46 Illinois N.'vtur.ai. History Survey Bulletin Vol. 25, Art. 2 parallel, but less severe, mortality rate, table 2. In the transects selected for study, the number of trees in mud was small ; also, the ultimate effect of mud, after 8 years, was less obvious than that of water, since reactions in this medium were slower. In view of the small area of mud in the transects, supplementary observations were made in October, 1944. The data obtained vary from those of the transect samples only in method and places of col- lection. As presented in table 5, the sup- plementary data represent a special effort to enlarge the mud sample, particularly for Cottonwood, birch, hackberry, persim- mon, pecan, buttonbush, and pin oak. They were collected from strips running parallel to mud fiats rather than at right angles to them. These parallel strips were near transects 1, 6, and 7, and were 30 to 50 feet wide ; trees were taken in order of occurrence, regardless of species, size, or condition. It is believed that this procedure eliminated the error of selectiv- ity, and, since the two sets of data show similar trends, together they give added reliability to the conclusions. Raising of the water table so as to turn low ridges into mud flats resulted in tim- ber mortality at the end of 6 years that ranged from 50 per cent to nearly 100 per cent, except for such species as privet, white ash, river birch, and Cottonwood. The species best able to tolerate change of this kind clearly are waterprivet and but- tonbush, as would be expected. By 1946, it appeared likely that a higher percentage of trees of all species would die in time, and that the mud flats would support cat- tail (Typlia latifolia) or other marsh plants, or grow up to willow, cottonwood, white ash, and perhaps other forest repro- duction, fig. 20. Extensive invasion of] cattail, and, in some cases, arrowhead or* duckpotato (Sagitlaria spp. ) , fig. 8, had occurred prior to the extreme floods of April and May, 1943 and 1944, which} destroyed most of them. In 1946, these- marsh plants were reappearing. In a study of the influence of flooding in upper Mississippi River pools, Green (1947) noted few deleterious effects on timber growing on land higher than the contour 2 feet above normal pool level. In the present study, the "mud" sample lay lower than the 2-foot contour, being in fact where the water table lay at or very, near the ground surface. Green noted the appearance of forest reproduction on cleared area between pool stage and the 2-foot contour. Similar observations werei recorded many times during the present investigation. Trees Standing on Land Even for land not actually flooded the water table was raised approximately 3. feet as a result of closing the Alton Dam.i Table 5.—Mortality in various species of trees on mud sites in study area, Calhouni County, Illinois, October, 1944. Permanent flooding of area was begun in June, 1938. Species August, 1949 Yeager: Effect of Permanext Flooding 47 Fi^. 8.-—Cattail, rice i- u _ i- i iiclipotato. smartweed, and other marsh or moist-soil plants invading timheriand where the \Nater tahle hati been raised to the soil surface. Timber stand is dead or dying. October. 1941. 1 hat timber stands were attected thereby was apparent, though not conspicuously so except in pin oak. This species, even i)n the unrtooded land, suffered a mortal- ity of 28.2 per cent by October, 1944, lit- tle iTiore than 6 years after initial impoundment, and d\ ing was noticeably progressive. Mortality in other common species was much lower, table 2. White ash, pecan, cottonwood, waterprivet, and several other species on unflooded land showed no loss as a result of the rise in the water table. Willow and buttonbush were not represented in the land sample. By October, 1944, the two most numer- ous species on the area, silver maple and American elm, showed losses of 5.1 and 6.1 per cent, respectively, probably some- what greater than natural mortality in stands where large poles and standards predominate. On land, the greatest loss in both maple and elm. as well as other species, was in the very large, overmature trees. The other coinmon river-bottom species, persimmon, hackherry, and water- locust, showed only slightly lower death rates than maple and elm. The death of two very large, old hawthorns, among 17 trees of this genus growing on land in the transects, is believed to have resulted from natural causes, rather than flooding, as other hawthorns growing outside of the transects were obser\'ed to be tolerant of the raised water table. Discussion Pin oak was easily the species most sus- ceptible to injury by flooding, showing sNiiiptoms of dying as well as complete mortality before any other. Pin oak trees flooded in June, 1938, were clearly in a dying ct)ndition in September, 1939; by June, 1940, over 70 per cent had died, table 2. All were dead b> October, 1940. In water, river birch indicated a slightly higher mortality rate than pin oak by June, 1940, but a somewhat slower dying rate thereafter. Pin oak trees in mud and on land sites with raised water le\els died less rapidh' than those in water, but all in mud succumbed before October, 1942, little more than 4 years after the original impoundment. A water table 48 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 raised to the ground le\el (trees in mud) was less injurious to river birch than to pin oak. Of the trees in water, hawthorn and silver maple, in June, 1940, were third and fourth, respectively, in rate of dying. The approximate number of years at which various species reached 100 per cent mor- tality is shown in table 6. Fig. 9.—White ash was among the tree species most resistant to flooding. A few vigorous individuals, in less than 2 feet of water, threw trunk sprouts in 1946, during the ninth year of flooding. Two recently built duck blinds are shown in the center background. August, 1949 Yeacer: Effect of Permaxext Flooding 49 Some pin oak trees died in 1 year, and other species showed high loss at least 1 year before the time of 100 per cent mor- tality. Most maples (98.9 per cent) and elms (97.1 per cent) were dead in little more than 4 years, table 2. Survi\ing white ash and waterlocust trees at the end of 6 years were so severely injured that few showed leaf in 1946. However, a few white ash trees showed small green trunk sprouts in October of that year. low, liackberry, privet, and huttonbush bore appreciable crops; and trees of maple, elm, ash, ri\er birch, and pecan produced small crops. During the third year, wil- low, waterlocust, and waterprivet pro- duced sparse crops and huttonbush a nor- mal crop. Several persimmon trees grow- ing on a steep-banked slough (Chickahom- in\-, fig. 2) and with root systems inun- dated only on the lower or stream side, produced well in 1944. These trees died Table 6.—.\pproximate period of flooding, up to 3 feet, required to kill all trees of vari- ous species in six study transects, Calhoun County, Illinois. Two 50 Illinois Natural History Survey Bulletin Vol. 25, Art. Fig. 10.—Some pecans and other trees with root collar flooded on one side but above water level on the other side died first on the flooded side. maple, was especially noticeable in 1939 and 1940. Such root growth was most pronounced near the new water line, but, in decreasing density, it extended down the trunk and thus for several inches below the water surface. This reaction of certain woody species to the stimulus of a raised water level is, of course, well known. The effect of flooding on forest repro- duction was similar to that in parent trees. An 8-acre clearing south of Sawmill Slough showed in 1938 a dense stand of seedlings, with some stump sprouts of elm, maple, and other species. In Octo- ber, 1939, practically all of this repro- duction except that of white ash and waterlocust showed evidence of dying; in October, 1940, all was dead except white ash in a foot or less of water. Even the 4- to 6-foot ash seedlings succumbed where flooding occurred to a depth exceed- ing 12 or 15 inches. Of all species repre- sented, ash reproduction showed greatest tolerance to permanent flooding. August. 1949 Yeager: Effect of Permanent Flooding 51 TREE FALL Tree fall in the following discussion refers to the dropping of branches as well as to actual fall of the tree, wholly or in part, in flood-killed timber as a result of death, decay, and wind action. Rate and Manner of Falling Falling of water-killed trees was not particularly noticeable until 1941, 3 years after the initial flooding. Prior to this time scattered trees and large branches had crashed, but this early fall was prin- cipalh among the numerous large, multi- branched and decadent silver maples and small, badly suppressed trees of all spe- cies. Many of the large maples were 4 feet or more in diameter and some of them probabl\- would lia\ e fallen if flooding had not occurred, fig. 3. B\' October, 1944, falling was more or less advanced in all species, indicating, as would be expected. Fig. 11. — Silver maple wind-thrown in 1940, about 2 years after initial inundation of the Calhoun County >tudy area. Photographed In October, 1940. rapid decay in this low, humid localit\, figs. 11 and 12. Falling data arc summar- ized in table 7. The manner of falling in dead trees was confined to two general patterns, determined by the presence or absence of durable heart\\ood. Among the species having durable heartwood, pin oak was outstanding. Although the first to suc- cumb to flooding, pin oak was the last to fall after death. Bur oak showed rather similar characteristics. Oak branches, particularly the larger ones, were slow to fall, since they contained a considerable \olume of heartwood. In oaks, the sap- wood decayed and fell usually off both trunk and larger branches, leaving stand- ing skeletons of heartwood. Five years or more were required for this degree of deca\'. Dead oaks with sound wood were usually uprooted by winds rather than broken off, although in oaks weakened by advanced heart rot the reverse was true. \Vaterl()cust. except for the larger trees, many of which were decadent, possessed strong heartwood and stood well. Branches of locust trees tended to fall after a year or two. White ash, with only fairly durable heartwood, and often with ad- vanced heart rot in the larger trees, was intermediate in ability to stand. There is a long list of rixer-bottom trees known to have quick-rotting heart- wood. Most numerous of these trees on the study area were silver maple, Ameri- can elm, pecan, persiminon, sugar hack- berry, Cottonwood, ri\er birch, and wil- low. Of these species persimmon and over- mature inaple trees fell first. Multi- branched, spreading trees of all species characteristically lost their branches, leav- ing low, stubby, and often hollow snags. X'igorous maple, hackberry, birch, and willow trees were somewhat slower in fall- ing, and all fell at about the same rate. Ainong species having nondurable heart- wood, elm, pecan, and Cottonwood were most resistant to falling. Cottonwood \\as surprisingly durable; mature trees (lying in 1942 and possibly earlier were cut for lumber in the fall of 1944. Such trees, while having decayed sapwood, usually showed sound, though often stained, heart- wood ; they had been vigorous in life; and many of thein were 2 and some 3 or more feet in diameter, fig. 13. 52 Illinois Natur.al History Survey Bulletin Vol. 25, Art. 2 Table 7.—Degree of falling in river-bottom timber on six study transects, October, 1944 and 1946, Calhoun County, Illinois.* Permanent flooding of area was begun in June, 1938. August. 1949 Yeacer: Effect of Permanknt FLooDisn 53 landed on end, becoming deeply embedded in the soft mud bottom. Many tree trunks, e\en when they tell in water deep enough to float them, became waterlogged and sank. Trees falling in shallow water. Cottonwood and willow, are constant sources of river driftwood. Clearing of the shore lines appears to be the most prac- tical method of reducing the amount of driftwood which, in navigable streams, is Fig. 12.—Same log as in tig. 11, October, 1945. Dying in 1939 ami falling in 1940, this maple showed advanced decay and disintegration, to be expected of nondurable woods in low, humid localities in the temperate zone. unless held up by other falls, settled in the mud. Thus, logs and tops tended to remain on or very near the site of fall, or, if dislodged, were soon caught against the thousands of trees and stubs that cov- ered the area. Comparatively few of these logs reached the Illinois and Missis- sippi rivers froin the interior of the Pere Marquette tract, even during the severe floods of 144.? and l')44. Many green or flood-killed trees that have grown along the shores of navigable streams are uprooted and swept into the main channels. Flooded, uncleared islands in the Mississippi River, covered mostly by an appreciable nuisance or e\en a hazard to river shippmg and also to commercial fishing. That few logs from Calhoun Point reached the Mississippi River was due to the fact that, prior to flooding, an exten- sive and thorough clearing operation had been performed along the Illinois Ri\er >hore line. Much of the Mississippi River shore line at this point is low bluff, some- what higher than pool stage. For this reason little or no tree mortality occurred from the rise in water level, and no dead timber from this shore reached the river channel. 54 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 ^v-. Fig. 13.—A 42-inch Cottonwood flooded about 4 inches on the lower side in 1938. It died in 1942 and was cut for lumber in 1944. The heartweod was stil! sound but stained in October, 1946. POST-FLOODING SUCCESSION General, and for the most part inci- dental, observations on changes in plant and animal life subsequent to flooding were recorded during the investigation. Verj' profound changes are, of course, still in progress; this report is merely a summary of early succession phenomena. Plants The most conspicuous change in plant life was that of death in flooded timber. At the end of 8 years, most of the dead and fallen stand was in water less than 3 feet deep. Conversion of much of this area, log- filled and snag-studded, to marsh was to be expected, and this transition had begun before 1946. Ecological development in the area following flooding may be ascribed largel\' to spread of plants already present and to introduction of seeds b) water. As early as 1938, 2 jears after excavation, borrow pits on the east end of the area supported vigorous stands of cattail (Typha lalifolia). By 1940, cattail stands had appeared in a scattered pattern on most of the water areas, as well as on wooded sites (timber dead) where the water table approached the ground sur- face, fig. 8. Stands of duckpotato (Sagit- taria spp.) were particularly abundant along the lower end of Big Slough, where the channel had been deepened. Along the shore lines of both the Illinois and Mississippi rivers, rows of smartweed (Polygonum spp.) and cockspur or wild millet (Echinochloa spp.) appeared in both mixed and pure stands, undoubtedly due to the windrowing effect of wave action, fig. 16. Luxuriant growths of rice cut- grass (Leersia oryzoides) developed along the margins of many flooded areas in 1946, fig. 17. Water in the sloughs and lakes, back- water in nature and without current except that induced by the rise and fall in pool levels, became progressively clearer toward the head of such bodies, even with the ini- tial inundation in 1938. This condition permitted luxuriant growths of coontail or hornwort ( Ceratophyliuni deinersum) and leafy pondweed (Potamoyeton foliosus), which became very noticeable in 1939 and reached their greatest development in August, 1949 Yeager: Effect of Permanent Flooding 55 1942. Very heavy stands of sedfjes (Carex spp.) sprang up along some of the more open shiughs and shallow-water areas. The water supported a laser of duckweed (Letinui. Jl'olffia, and Spirudela) , com- monly 1 inch thick, figs. 6 and 18. Fila- mentous algae covered e\ery suhmerged ohject, fig. 19. E.xtreme flood conditions during the early growing seasons of 1943, 1944, and 1945 had a profound effect on suhmerged and most emergent vegetation. The smothering effect of muddy, silt-laden flood water severely decreased the stands; during the summer and fall of 1943 and 1944, onlv scattered growths appeared; bv 1945. all the plants mentioned above except duckpotato virtually disappeared from the area, hut manv of tliem had reap- peared by the fall of the following year. Moist-soil species, particularly rice cut- grass, appeared in dense stands in 1946, probably from seed deposited by Hood waters. Forest reproduction, principaliv wilhjw and Cottonwood, appeared along the shore lines of the Mississippi and Illinois rivers as early as 193^5, particularlv where clear- ing had been done. Growth was vigorous in 1940. These species also appeared along the shore lines of the shallower and more open sloughs. Seeding was of course by wind and water from numerous parent trees still present on surrounding unflooded land. On certain wet "Hats," notably north- west of Lower Roval Lake and along part of the Illinois River shore line, silver Fig. 14.—A silver maple stand, October, 1946, 8 years after inundation, showing falling and break-off characteristic of species having nondurable heartwood. 56 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 Fig. 15. Silver maple "flat," flooded in 1938; a maze of fallen debris in October, 1946. Fig. 16.— Stand of smartweed (Polygonum spp., chiefly lapathifolium) along the Illinois River on Calhoun Point, October, 1941. Seed presumably "windrowed" by wave action. August, 1949 Yeager: Effect of Permanent Flooding 57 maple reproduction was abundant in Octo- ber, 1944, reaching a density of four stems per square foot on small areas. AVhite ash and American elm seedlings were common. Some pecan and pin oak repro- duction was noted at \ arious points. By October, 1946, practically all open, un- flooded land supported a fair to full stand of river-bottom forest seedlings. Maple, elm, ash, willow, Cottonwood, pin oak, and pecan reproduction was growing vigor- ously at this time ; in some places it was as much as 10 or more feet high, fig. 20. Manimals Among mammals, muskrats (Ondatra zibelhicus zibet hiiiis) were most recep- tive to conditions brought about by per- manent flooding of about one-fourth of Calhoun Point. In a complete coverage of the area in Februarv, 1938, Frank C Fig. 17.—Rice cutgrass had attained luxuriant stands along the margins of flooded woodland in the study area by October, 19+6. 58 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 Fig. 18.—Mat of duckweed an inch thick covered much of Royal Lake, Calhoun Point, Octo- ber, 1941. Fig. 19.—Filamentous algae grew in heavy mats over every submerged object, here revealed by a 16-inch drawdown, October, 1940. August. 1949 '^'eacer: Effect of Pek.maxext Flooding 59 Fig. 20.—Willow, cottoinvooii, elm, and silver maple reproduction on mud flat following death of most of the original stand as a result of flooding that raised the permanent water level nearly to the ground surface. .-^ luxuriant stand of rice cutgrass grew between the bare mud flat and the forest zone in October, 1946. Bellrose, Jr., of the Illinois Natural His- tory Survey (personal communication) found no sign indicating the presence of these aniinals. In April of that year, temporary closing of the Alton Dam flooded the borrow pits and sloughs along the rivers, and within a few days musk- rats appeared. Muskrat signs were fairly common on June 2, 1938, and in places abundant in October of the same year. Strong evidence was found during the next 3 >ears that muskrats were increasing in numbers. By October, 1940, muskrat icutting? (chiefly of cattails and sedges), droppings, and burrows were noted in or near practically everv slough on the area, f^K.21. The steady increase in numbers of muskrats in the Calhoun Point study area (Yeager ^" Rennels 1943) is reflected by complete or partial counts of trappers' :atches for hve seasons, as follows: Tr.*ppisg Season .\IisKRATS Trapped 1938-39 60 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 lotor) numbers during the next 2 or 3 years. However, this species, on Calhoun Point as elsewhere throughout its range, showed strong recovery by 1943. The raccoon population on the study area was high in 1944. Opossums (Didelphis virginiana virgini- tina), never heavily trapped or hunted floods reached their peaks during the young-rearing seasons. It is therefore not improbable that most of the animals, except those near the river bluffs, perished, during the inundation. It should be re- membered that, however well housed above the water level, any animal without food will find itself in dire straits before Fig. 21.—Muskrat burrows under an old stump exposed by a drawdown of the water level of the Illinois River at Calhoun Point, October, 1940. The animals had attempted to plug entrances following exposure. after about 1939 because of low fur prices, remained numerous on Calhoun Point until 1943, when floods of that year and 1944 apparently reduced their numbers to a very low point. Astonishing as it may seem, not a single opossum track was seen during an inspection trip over the area that lasted from October 13 to 18, 1944, although special efforts under excellent conditions were made to find such tracks. No reason other than flooding can be given for the scarcity of opossums. These ani- mals are good climbers but not good swim- mers, and they do not possess marked abil- ity to take food from water. Since the entire point was flooded to a depth of sev- eral feet in both years, opossums there were separated from land by flood waters for as much as 3 miles. Moreover, the the end of a 2- or 3-week flood peak. Opossums showed some indication of coming back to Calhoun Point by Octo- ber, 1946, but at that time they were far below their 1942 numbers. Minks (Mustela vison), animals that are highly adaptable and equally at home on land or in water, were affected b} the Calhoun Point floods less than any other fur species. Signs indicating substantial populations were noted during every year of the study. Both red foxes (Vulpes fulva) and gray foxes (Urocyon cinereoargenteus cinereo- argenleus) were present on Calhoun Point previous to the initial flooding in 1938. Flooding reduced the habitable area for both species, and the peak floods of 1943 and 1944 undoubtedly evicted August, 1949 Ycager: Effect of Permanent Fiooping 61 hem from the area. Abundant signs of oxes were never observed on the study rea after 1Q44. though fox density on djacent, but higher, areas remained at a ery high point tor several years. Striped skunks (Mephitis mephitis) lere more numerous in 1^38 than at any ther time of the stud\ . E\ en in that year ens appeared to be confined to the high- st ridge—the fallow field and the woods the north of the field, both east of Big Hough. Flooding and the resultant 3- oot rise in the permanent water level indoubtedly made the area less suitable or this ground-denning species. Woodchucks ( .Mtiriiiotti rnoniix munax) Iso were adversely affected by permanent loading, although along the higher ridges heir dens and other signs were fairly com- non in October of 2 vears of this studv, 944 and 1946. Calhoun Point has long been a favored ocality for squirrel hunters. Until about 940. gray squirrels ( Sciurus caroHnensis) iredominated, as was attested by numerous lunters. Fox squirrels (Sciurus niger rufi- enter) , until that time, were most com- non along the pin oak ridges bordering he large opening in the center of the area ind along Big Slough and the west bound- iry. both territories adjoined by cultivated ields. \Vith the death of large tracts of iooded timber and the resultant opening ip of the stands, fox squirrels became the lominant species over practically the •ntire area. In October, 1944, the writer :overed every part of the 4-square-mile ract and observed a total of 24 fox squir- rels and 4 gray squirrels. Previously, the two species were more nearly equal in numbers. Cottontail rabbits (Sylvilagus flurida- iius) were notably scarce on Calhoun Point, e\en before the 1943 and UH4 floods, which undoubtedh evicted them from the tract. They \\ere more common along the inland boundaries of the area, and on adjacent farm land, a circumstance to be expected in view of the ver\' low, wet nature of the greater part of Calhoun Point. Both food and nesting conditions on the study area were obviously less fa\or- ahle than where waste grain, chners. and other farm crops afforded abundant fo(jd, and higher sites provided safer nesting grounds. Birds Succession in bird life on this tract of Hooded bottomland is indicated here onh from general observations. .Aquatic and marsh species, common before 1938, had become more numerous by 1944. Some indication of the increase is reflected in table 8, the data for which were taken from one 7-mile boat or canoe trip in each of 4 years on Big Slough, Royal Lake, Chickahominy Slough, and the Illinois River. The same route was followed at each observation. The general validity of the data in table 8 is strengthened by a number of other trips over the tract that \ ielded similar information. Calhoun Point has been subjected to heavy duck hunting since 1938. One hun- Table 8.—Numbers of birds observed on itudv area in each of 4 years. a 7-mile water trip through Pere Marquette 62 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 dred or more blinds scattered through the 4-squ;ue-inile area resulted in widespread shooting almost daily during each hunting season. Because waterfowl were thus dis- couraged during the fall in their attempts to use the new marsh and flooded wood- land, evaluation of the area for water- fowl purposes has been complicated. However, the tract became potentially more attractive to dabbling ducks in its flooded state than it was formerly, because of the larger shallow water area and the development of rice cutgrass, fig. 17, smartweed, fig. 16, wild millet, and other aquatic and moist-soil plants that furnish food for ducks. Wood ducks (Aix sponsa) are the only wild waterfowl that nested in the area. Yearly observations by Frank C. Bellrose, Jr., and other members of the Natural History Survey staff indicate a severalfold increase in breeding and summer popula- tions of these birds since 1938, apparently because of the greater area of attractive habitat. Nesting sites in the hundreds of hollow snags and trees are ample ; and quiet, duckweed-covered waters in the flooded timberlands are probably ideal as rearing grounds. There was some evi- dence in 1946 of decreasing attractiveness of the area to wood ducks as a result of the opening up of flooded woodland and the trend toward the marsh stage of suc- cession. There was abundant evidence during much of the study period of a general increase in number of herons on the area. After 1941, a score or more of these birds could often be counted at a single stand, and, by including all of the concentration areas on the point, 500 to 700 herons could easilv ha\e been recorded in a dav's time. On August 6, 1941, Harry G." Ander- son, an ornithologist associated with the Natural History Survey, and the writer counted 200 American egrets (Casriiero- dius albus egretta), 12 snowy egrets (Egretta thula thula), and 40 great blue herons (Ardea herodias herodias) on one 20-acre bay. None of these birds is included in table 8. In June, 1941, four green heron (Butorides virescens) rooker- ies, averaging 20 nests each, were found in the course of routine work. Systematic coverage of the tract would probably have disclosed others. The 600 or more acres of shallow water, abounding in minnows, small fish, frogs, crayfish, and other food, afforded excellent foraging grounds for all species of wading birds present. With the appearance of marsh, breeding populations of red-wing blackbirds (Age- laius phoeniceus phoeniceus) became estab- lished in 1938. On May 15, 1942, Harry G. Anderson and the writer counted 22 . red-wing nests in less than one-half acre f of cattail marsh in Sawmill Slough, north of Coon Lake. This was near the middle of the area ; other red-wing colonies were found in the various cattail stands along the Illinois River, Big Slough, and other places. The 10 red-wings noted on August 6, 1938, table 8, were in the vicinity of a cattail marsh at the mouth of Chickahom- iny Slough. Highly suitable nesting and food condi- tions for woodpeckers were provided by the thousands of dead trees, in every con- dition of decay, on Calhoun Point. An increase of woodpeckers on the area was noticeable as early as October, 1939, fol- lowing the death of numerous maple and other trees. As listed in table 8, at least six species were observed, of which the red- headed woodpecker (Melaiierpes erythro- cephalus) was most common. Next in numerical abundance was probably the red-bellied woodpecker (Centurus caro- linus) ; the flicker (Colaptes atiratus liiteus) was third. An unusual number of pileated woodpeckers (Ceophloeus pile- (itus abieticola) were present, the writer observing 13 on the morning of October 14, 1944. At least six were in one scat- tered flock. Downy (Dryobates pube- sceris) and hairy woodpeckers (D. villo- sus) were other species recorded. No attempt was made to determine the effect of flooding on perching birds. Such conspicuous forms as the prothonotary warbler (Protonotaria citrea) and Amer- ican redstart (Septophaga ruticilla) were abundant on the area in years covered by this report. Harry G. Anderson and the writer recorded 45 of the former and 30 of the latter on May 15, 1942. A total of 66 species of birds were listed on that date, but it is certain that many of these were migrants. General evidence indi- cates that the prothonotary warbler, at least, increased over the population pres- ent on the area is 1938. \ugust, 1949 Yeager: Effect of Permanent Flooding 63 Starlings (S/urnus vuli/tiris vulyaris) ,vere observed in considerable numbers on he area in October, 1946. SUMMARY 1. Timber killed by impoundment of Aater for power development, channel mprovement, flood control, and other lurposes represents a problem of growing mportance throughout the United States. 2. The effect of water impoundment )n timber was studied over an 8-year leriod, 1939-1946, at the junction of the Mississippi and Illinois rivers, where siz- ible tracts of river-bottom timber were cilled by the Alton Dam impoimdment, irst pooled in 1938. 3. The study area, Calhoun Point, consisted of 2,200 acres of river-bottom rorest, sloughs, lakes, and small marshes. About 600 acres of this tract were flooded lermanently by the Alton Dam, which aised the average summer water stage ibout 3 feet. This rise in level reduced :he highest elevation on Calhoun Point from 10 to 7 feet above the a\erage sum- iier water surface. 4. Timber stands on the studs area verc all-age, river-bottom hardwoods rharacteristic of the upper Mississippi Ri\er valle\. Silver maple was easily the dominant species; American elm, white ish, pin oak, pecan, river birch, cotton- ivood, black willow, persimmon, hack- aerry. and waterlocust were other com- non species. Important shrubs were but- :onbush, waterpri\et, and deciduous holly. 5. The effects of flooding were studied an sample areas, consisting of six 50-foot transects, aggregating 3.5 miles in length. These transects crossed all representati\e timber types on Calhoun Point. Indixid- iial trees in the sample were identified by numbered metal tags attached \\ith gal- lanized nails at breast height. Records involving species, d.b.h., crown class, gen- eral vigor, depth flooded, and year of tieath were taken at intervals. A total af six inspections, in addition to the one St time of tagging, and numerous visits at ither seasons, supplieil the data for this 'eport. 6. River stages, 1937-1946, at Graf- on, Illinois, less than 2 miles downstream rom the area, were studied in relation to the rate of dying in tree species and suc- cession in aquatic vegetation. 7. The effect of flooding on timber was studied under three categories: (1) timber actually flooded; (2) timber on sites where the water table had been raised to the ground surface; and (3) timber on unflooded land, where the average sum- mer water table had been raised approxi- mately 3 feet. 8. Eight years of actual flooding of timber areas resulted in practically com- plete tree mortality. In most tree species, flooding to a depth sufficient to cover the root collar, less than 20 inches, was fatal. Rate of dying showed wide variation by species. Pin oak was most susceptible to injury from flooding, all individuals of this species dying before or during the third \ear. White ash was most resistant, a few individuals giving rise to trunk sprouts 8 years after inundation. Mortal- ity in most other tree species was 100 per cent in 6 years. Waterlocust showed a mortality of 96.0 per cent and black wil- low 43.5 per cent in 6 years; a few trees of these species were still alive 8 years after impoundment. All bur oak trees \\ere dead 3 years after permanent flood- ing was begun ; all persimmon, hackberry, hawthorn, river birch, and Cottonwood were dead in little more than 4 years. Most silver maple was dead in about 4 \ears; all silver maple, American elm, and pecan were dead in about 6 3 ears. 9. The three shrub (or small tree) species represented in the water sample likewise varied in tolerance to flooding. Deciduous holly showed 100 per cent mortality in about 4 years. Waterprivet, in October, 1946, more than 8 years after flooding, showed S5 per cent mortality ; sur\i\ing indi\ iduals were in less than 2 feet of water. It appeared in 1946 that some of these would li\e. Buttonbush was definitely the most tolerant species sampled, this shrub showing a survival of 40 per cent or more except when deepl.\' submerged. 10. The diameter of trees and shrubs sidijected to flooding had little influence on their death rate. An apparent differ- ence in the 2-inch class was due to species rather than to size. In general, within each species, healthy, vigorous trees showed the greatest resistance to flooding, and the 64 Illinois Natural History Survey Bulletin Vol. 25, Art. 2 very small class (other than in semiaqua- tic species) and the overmature class showed the least resistance. The depth flooded (short of submersion) likewise appeared to make little difference, provided the root collar was covered. A depth of less than 20 inches was sufficient to cover the root collar of all species involved. 11. The harmful effect of a raised water table was clearly discernible, partic- ularly where mud conditions were cre- ated, but, for each species, tree mortality was less severe in mud than in water. To mud, as to water conditions, pin oak was very susceptible and white ash very resist- ant; semiaquatic shrubs like waterprivet showed no mortality in mud. 12. On land above the mud level, but subjected to a 3-foot rise in the water table, only pin oak showed conspicuous reaction. Here, at the end of approxi- mately 6 years, mortality among trees of this species had reached 28.2 per cent and was noticeably progressive. Losses in elm and maple were much lower, and white ash, pecan, cottonwood, and several other trees and shrubs apparently were unaf- fected by the increased water level. 13. Several tree species bore fruit un- der flooded conditions. This occurrence was most pronounced during the first 2 years. Only willow, waterlocust, water- privet, and buttonbush produced fruit dur- ing the third year subsequent to inunda- tion. 14. Trees with root systems flooded only on one side showed differential dying rates in parts of the same tree, the side inundated being nearly always the first to die. 15. Willow, white ash, and button- bush showed marked ability to set adven- titious roots during the first 2 or 3 years of flooding. Silver maple showed this ability to a lower degree. 16. The effect of flooding on forest reproduction was similar to that on par- ent trees. White ash reproduction showed by far the greatest tolerance to flood con- ditions. 17. Falling of dead timber became noticeable 3 years after flooding ; it was advanced 6 years afterward, and e.xtremely pronounced 8 years afterward. Pin oak showed greatest resistance to trunk fall ; other species, without durable heartwood, snapped off at varying distances along the trunk. 18. Dead timber falling on the study area became waterlogged or deeply embed- ded in mud. Few falls reached the Mis- sissippi and Illinois rivers to offer hazards to shipping and commercial fishing. 19. By 1946, conversion to marsh of the flooded bottomland, then a jumble of fallen logs and debris lying in mud and shallow water, had begun. Cattail, duck- potato, and various sedges were the most common marsh invaders ; smartweed, wild millet, and rice cutgrass held a similar position on moist soil. 20. Extremely heavy growths of coon- tail and leafy pondweed, often covered in the fall by a mat of duckweed, appeared in the clear-water sloughs and lakes dur- ing the first 4 years of flooding. 21. Floods, several feet above normal pool stage in 1943, 1944, and 1945, destroyed practically all submerged and emergent aquatic vegetation, but, by the fall of 1946 several species showed evi- dence of recovery. 22. Reproduction of river-bottom tree species was common in 1944, and, in 1946, seedlings of maple, elm, ash, willow, cot- tonwood, pin oak, and pecan were grow- ing vigorously. 23. Among mammals, muskrats showed great adaptability to conditions induced by flooding. The severe floods of 1943 and 1944, and a lesser flood in 1945, apparently depleted their numbers, but there was evidence of recovery byl October, 1946. Opossums and cottontail|i rabbits were apparently evicted from the area by the series of high waters. 24. Raccoons and minks, with some fluctuations in populations, remained com- mon to abundant in the area throughout the period of study. 25. Land mammals, such as wood- chucks, skunks, and foxes, found less and poorer habitat on the area after flooding in 1938 than previously. The 3-foot rise in the water table undoubtedly limited the area suitable for ground dens on this low flood plain. 26. Flooding improved the Calhoun Point habitat for wood ducks, herons, and woodpeckers, and was attended by notice- able increases in the populations of these three groups. The increase was perhaps, I August, 1949 Yeager: Effect of Permanent Flooding 65 Tiost conspicuous in woodpeckers, for marsh was accompanied by increases in Ivhich the thousands of dead and dying the number of nesting red-wing blackbirds, trees provided unlimited food and nest- Considerable numbers of starlings were ng sites. The development of cattail obser\ed on the area in 1946. LITERATURE CITED Vmerican Ornithologists' Union 1931. Check-list of North .American birds, fourth edition. 526 pp. American Ornithologists' I'nion. Lancaster, Pa. jreen. William E. 1947. Effect of water impoundment on tree mortality and growth. Jour. Forestry 45(2) : 118-20. elsey, Harlan P., and William A. Dayton, eds. 1942. Stanilardized plant names, second edition. 675 pp. J. Horace McFarland Co., Harris- burg, Pa. lecker, Walter L., and Donald M. Hatfield 1941, Mammals of Illinois. Chicago Acad. Sci. Bui 6(3) :17-60. eager, Lee E., and R. G. Rennels 1943. Fur vield and autumn foods of the raccoon in Illinois river bottom lands. Jour. Wild- life Mgt. 7(1) :45-60. Recent Publications A.—ILLINOIS NATURAL HISTORY SURVEY BULLETIN. Volume 22, Article 1.—The Plant Bugs, or Miridac, of Illinois. By Harry H. Knq September, 1941. 234 pp., frontis. + 181 figs., bibliog., index. $1.25. Volume 22, Article 2.—Studies of North American Plecoptera, with special referenc the fauna of Illinois. By T. H. Frison. September, 1942. 122 pp., frontis. + 126 i bibliog., index. $1.00. Volume 22, Article 6.—Survey of the Illinois Fur Resource. By Louis G. Brown and Lee E. Yeager. September, 1943. 70 pp., frontis. + 33 figs., bibliog. (Bound with: Article 7.) Volume 22, Article 7.—Illinois Furbearer Distribution and Income. By Carl O. Mohri^ September, 1943. 33 pp., frontis. + 24 figs., bibliog. (Bound with Article 6.) Volume 23, Article 1.—The Caddis Flies, or Trichoptera, of Illinois. By Herbert H,' Ross. August, 1944. 326 pp., frontis. + 961 figs., bibliog., index. $1.50. ^ Volume 23, Article 2.—Duck Populations and Kill. By Frank C. Bellrose, Jr. Novem-^ ber, 1944. 46 pp., frontis. + 27 figs., bibliog. 50 cents. V^olume 23, Article 3.—Overfishing in a Small Artificial Lake: Onized Lake near Alton, Illinois. By George W. Bennett. May, 1945. 34 pp., frontis. + 15 figs., bibliog. Volume 23, Article 4.—Wetwood of Elms. By J. Cedric Carter. August, 1945. 42 pp., frontis. + 30 figs., bibliog. Volume 23, Article 5.—Fox Squirrels and Gray Squirrels in Illinois. By Louis Q, Brown and Lee E. Yeager. September, 1945. 88 pp., frontis. + 42 figs., bibliog. Volume 24, Article 1.—The Mosquitoes of Illinois (Diptera, Culicidae). By Herbert H. Ross. August, 1947. 96 pp., frontis. + 184 figs., bibliog. 50 cents. ' Volume 24, Article 2.—The Leafhoppers, or Cicadellidae, of Illinois (Eurymelinae-j Balcluthinae). By D. M. DeLong. June, 1948. 280 pp. + 514 figs., bibliog., index, $1.25. Volume 24, Article 3.—The Bass-Bluegill Combination in a Small Artificial Lake. George W. Bennett. December, 1948. 36 pp., frontis. + 10 figs. Volume 24, Article 4.—The Pseudoscorpions of Illinois. By C. Clayton Ho£E. Jb 1949. 86 pp., frontis. + 51 figs., bibliog., index. 50 cents. Volume 25, Article 1.—Characteristics of Residual Insecticides Toxic to the House Fly^J By Willis N. Bruce. July, 1949. 32 pp., frontis. + 14 figs., bibliog. B.—ILLINOIS NATURAL HISTORY SURVEY CIRCULAR. 32.—Pleasure With Plants. By L. R. Tehon. February, 1949. (Third printing, widlj revisions.) 32 pp., frontis. + 9 figs. 34.—Rout the Weeds! Why, When and How. By L. R. Tehon. September, IS (Fourth printing, with revisions.) 47 pp., color frontis. + 13 figs. 36.—Planting and Care of Shade Trees. By J. E. Davis. September, 1947. (Tbir printing, with additions.) 28 pp., frontis. + 20 figs. 38.—^Windbreaks for Illinois Farmsteads. By J. E. Davis. February, 1949. (Thif printing, with additions by L. B. Culver.) 33 pp., frontis. + 27 figs. 39.—How to Collect and Preserve Insects. By H. H. Ross. July, 1949. 59 frontis., + 65 figs. 41.—How to Recognize and Control Termites in Illinois. By B. G. Berger. February^l 1947. 44 pp., frontis. + 32 figs. 42.—Bird Dogs in Sport and Conservation. By Ralph E. Yeatter. December, 19 64 pp., frontis. + 40 figs. G.—ILLINOIS NATURAL HISTORY SURVEY MANUAL. 2.—Fieldbook of Illinois Land Snails. By Frank Collins Baker. August, 1939. 166 pp,f color frontis. + 170 figs., 8 pis. $1.00. 3.—Fieldbook of Native Illinois Shrubs. By Leo R. Tehon. December, 1942. 307 4 color pis. + 72 figs., glossary, index. $1.25. List of available publications, about 400 titles, mailed on request.' Single copies of Illinois Natural History Survey publications for which no price is liitedj! will be furnished free of charge to individuals until the supply becomes low, after which ••« nominal charge may be made. More than one copy of any free publication may be obtaine^r without cost by educational institutions and official organizations within the State of IlliDoil; prices to others on quantity orders of these publications will be quoted upon request. Address orders and correspondence to the Chief Illinois Natural History Survey Natural Resources Building, Urbana, Illinois