Report on Department of Forestry Research Project 123, 'Ecological Studies'--P. [2].Digitized 2007 AES.Includes bibliographical references (page 11)

McDermott, R. E. (Robert Emmet), 1920-

University of Missouri: MOspace

RESEAR CH BULLETIN 557 JUi Y , 1954 UNIVERSITY OF MISSOURI COLLEGE OF AGRICULTURE AGRICULTUR:1LL EXPERIMENT STATION J H . LONGWELL, Director Seedling Tolerance as a Factor In Bottomland Timber Succession R. E. McDERMOTT (PubliC1l.!ion aUlborizedJuly 22, 19'4) COLUMBIA, MISSOURI TABLE OF CONTENTS Previous W ork ... . 3 Procedure ...... . . . . . ... . .... . .. ~ Results ...... . ........... . Discussion and Conclusions. Summary ...... . . . literaTUre Cited .. . .......................... . Report on DCf»rtmcnt of Fo restry Res=h Project 123, " Ecologiol Studies" 6 9 . ... 10 . . . ... 11 Seedling Tolerance As A Factor In Bottomland Timber Succession R. E. McDERMOTI T he problem of perpetuating valuable subclimlx species in bottomland areas is one of the greatest difficulties in bottomland timber management. After cuning, lftaS that had supported good stands of cottonwood and syca-more commonly revert to or become semi-stabilized in inferior species such as the elms. Numerous investig::nors h:avc reponed the successionlll sequence of bottomland timber species and, in general, the picture is one of valuable species being replaced by less vlluable species and these, in turn, being slowly replaced by more valuable species. Steyermark (1 940) found that along the smaller sue:ams of the southeastern Missouri Ourks, the first stage of woody succession on sand and gravel ncar a stream was commonly characterized by a temporary community or associes of willow-witch hazeL Sycamore may occur as a single dominant on gravelly, sandy deposits, or it may occur in associations with Ward's willow and wirch hazel. Another varia~ion in dose proximity to water may be an alder-witch hazel-sycamore assocles. Farther away from the margins of the streams, Steyermark repons a different associes of silver maple-eastern cottonwood. River birch, black willow, green ash, and red gum also may make an appearance in this stage. Stcyermark notes that fiver birch may come in before black willow, cotton-wood, and silver maple. The next forest community development away from a stream, according to Steyermark, is an American elm-green ash as-socies with a persistence oflatge sycamore, cottonwood, and black willow from the previous or streamward successional s~ge. Steyermark stares rhat this elm-ash associes may laSt almost indefinitely, depending upon pH of the soil and flooding activities of the stream. Shumard oak and bur oak may be present in this elm-ash stage. Sreyermark found that the final or climax stage of floodplain succession is characterized by the development of a sugar maple-bitternut hickory association. Winged elm is a common component of d .imax forest as well as the gums, hackberrics, oaks, and many other speCies. Steyermark describes the development of a white oak-red maple associa-tion in acid soil areas such as slight draws in ravines, heads of stream tribu-taries, and the upper slopes of hills and ravines. The first stage of this white oak-red maple association is described as a dogwood-blackgum associes that may have, in combination or as alternates, witch hazel or Ward's wil-4 MrssoUll AGIUCULTUIlAL EXPERIMBNT STATION low. As drainage are2S become more deeply dissected, red maple. mocktt-nut hickory, and winged elm IUC dominll.ms ; and the fin1i development is white oak-red maple. In his phycosociological studies of the plant communities of the North Carolina Pio::lmom area, Oosting (1942) includes an analysis of the bottom-lands. Although somewhat oversimplified, the general successional [fends 2fC: (1) alder-willow, (2) to river birch, or syc:amore, or boxelder, or mixo:l or prcdominanc1y red gum and yellow·poplar, and (3) to red maple-elm. "h. Oosting studied intensively three sands of birch and three of syca-more. H e found th:u in a six-year-old stand of river birch, birch reproduc-tion was predomln"nt, with sycamore, winged elm, :md red m~ple m~king up the bulk of the temainder in the order n~med. In a 14-year-old birch stllnd , reproduct ion tallies indicated an almost complere absence of birch, while red maple, red gum, and winged elm were most abundant. In ~ 36-year-old birch stand, no birch reproduction W2S in evidence and red maple-elm-ash made up 50 percent of the total. In 22-yeu-old, 30-year-old and 35-yeu-old sycamore stllnds, there W2S no sycamore tqlroducrion ; and in all three stands, red maple. elm, and ash, in wrying proportions, were the major constituents. Field data collected by che author in hotcombnds of the southeutem Missouri Oz~rks i ndic~te chat in stands of syc~more, river birch, ~nd COttOn-wood, reproduction of these sp«ies is ~lmost eompletely curt;l.iled with the development of canopy strat~. As a canopy develops, various kinds of re-production are found induding red gum, sugar maple, oaks, mulberry, etc., bue with a suong tendency toward elms. It is evident then, that if a merchannble stand of sycamore or COtton-wood is CUt, the next CUt may be limited to species that ue characteristic of the next stage of succession. In the southe~stern Ozarks of Missouri and the North Caro]jn~ Piedmont, this next unfavorable successional de-velopment is often coward some combination of elm, ash, andl or maple. The objective of this investigation was to determine why reproduc-t ion of the trees typial of the euly S[~ges of primary and secondary succes-sion in bottomb.nd are2S hils to concinue coming in under c:mopies, con-siSting in pan of these same species. In general, it can be Stated that the successionlll trend is towud more shade-tolennt species. However, the tol· crance of syamore is II m~tter of debate as Baker (1949) points our. T hus, llS II preliminary investigation, it seemed advantllgcous to ascertain the rela-tive light tolerances of young seedlings of tree species representing the sev-eral stages ofbottomb.nd succession. Sycllmore (Plantanus occitkntalis L ), river birch (Betula nigra L ), red maple (Actr rubrum L ), American elm ( Ulmus amtt7cana 1.), winged elm ( Ulmus alata Michx.), and hazel alder (AlnllJ rugosa [Du Roi] Spreng.), weee selected as representing early, mid-dle, llnd late stages of smllll su om, bottomland succession. RBS£AR.CH BULL£TIN ~57 , PROCEDURE Four light int~nsiti~s w~r~ us~d: full, on~-half, on~-third, and on~­fifth sunlight. On~-fifth full sunlight was used as a minimum because such iln int~nsity, according co Shirley (1943), is common under canop i~s and it is in this light rang~ that seedling establishment is greatest. The one· half intensity resulted from the filtering ~jfect of iln unwashed greenhouse roof, and the twO low~r int~nsi ties wer~ obtained by screens of cheesecloth. Full sunlight was obrain~d in an o~n area immediately adjacent to th~ green· house. Each treatment was applied to 50 seedlings in units of five ~r six-inch pot. The seedlings hild been transphnted into th~ pots after the appearance of the first true leav~s and were then allowed to srabilize for three dilYs be-fore being subj~cted to the light treatm~ms. As soon as seedling sil~ per-mitted, th~ surfaces of the potS w~re covered with a on~-half-inch hyer of granulated vermiculit~. T he indoor potS were S~t on cinder beds, and the outdoor pots w~re partially buried in sand. The soil used was a light potting soil with a wilting percentage of 9.93% and a field capacity of 19.73%. The one-third and one-fifth screens wer~ so constructed that tWO sides were suspended three inch~s above the cind~rs to allow air circuhtion. Th~ pots wer~ arranged in the same order by species in each treatment so that any shading effe<:t of th~ potS upon ~ach other would be of the same magnitude. This within-treatment shading effe<:t was judged to be at a min-imum b«ause of ample spacing. By frequ~nt watering and the use of the vermiculite mulch, m attempt was made to keep the moisture com~nt of the soil at field capacity or slightly above it. This was possible for the treatments wi thin the green-house, but nOt in the outdoor or full sunlight treatm~nt. Th~ light soil and underlying cind~r and sand beds provided rapid drainage. Survival, height growth, weight of the topS, and the weight of roots per pOt were recorded at the end of 15 weeks for sycamore, 14 weeks for alder, 13 weeks for red maple and the elms, and 10 weeks for river birch. Relativ~ humidity, air tem~ratur~, and sunlight intensiti~s were re-corded fo r 10 days during the experiment. Temr.;ratUJ"es under all treat-m~nts in the grc~nhouse were never more than 4 F apllt, but the outdoor t~mperatures were at different cim~s 13°f high~r ana 6°F lower than the indoor readings. Outdoor relative humidities prove:d to be consistently lower than th~ indoor humidities. The higher outdoor temperatur~s, St~ er atmospheric moisture gndients, and lower soil moistures produced a consistently dri~r environment in the: full sunlight treatment. In analyzing the growth data, it W3.S f~h that due to the pronounced environmental differences of th~ outdoor treatment, th~ growth results for full sunlight would hav~ [0 be evlluated sepuarely instead of pooling all residuals. The iltIalysis of indoor dan could have been made: on a pooled 27 6 MISSOURI AGRICULTURAL EXPERIMENT STATION degrees of frccdom, but the precision on 9 degrees of freedom W2S so close to that gained on 27 that pooling seemed unwarranted. Hence, all treat-ments were analyzed separately by species. Standard errors of individual tre:lcmems were used in c:alculating significa.nce of mean differences. RESULTS T he percentages of survival by species in each treatment:are presented in Table 1. H eight growth of the seedlings and the rarios of tOp weight to root weight per pOt were analyzed statistically (Tables '2. and 3). H eight growth of red maple did not differ significantly in any of the light intensities, and the tOp-root ratio differences atc significant for full sunlight only. H eight growth and top-root ratio of sycamore arc signifi-cantly less for full sunlight than for lowe:r light intensitie:s, and the differ. ence is significant for the ratios developed under one-fifth and one-third light. The elms diffe:r from e:ach other in that one·third light resulted in the significantly greatest height growth of American elm, while one-half light rc:sulted in the greates t height growth of winged elm. Interestingly, the: diff. erence: between the cop-root ratios of one-fifth and one-third light is signifi-cant for winged elm and not American elm, as are all the response:s of both under full light in comparison with those of reduce:d intensity. Sycamore, American elm, and alde:r had their highest top-root ratios under the light intensities which produced thdr greatest height growth, indicating perhaps, that best height gtowth resulted in the relatively poor-est root growth. H owever, actual rOOt development, as measured by weight, was greatest at this intensity for American dm, bur not for sycamore and alder. Like winged elm, the alder and river birch have their best growth at one:-half sunlight, but unlike elm, their height growth in full sunlight is significantly better than at one-fifth and one:-third sunlight intensity. Repre:sentative pOtS of the species that displaye:d significanc height growth responses are presented in Figs. 1 and 2. TABLE I __ River Birth . 100.0 1"00_0 100.0 81.5 100.0 "'., "'., 100.0 100.0 100_0 90.0 100.0 UNDER FOUR 90.0 62.5 45.0 11.5 TABLE 2 __ MEAN HElQHTS OF SEEDLINGS AND T HEIR [ R~d maple Sycamore Am. Elm ". TABLE' --Rcod Maple ~.mofe Am. Elm WI"... Elm • 'A __ -.--.~-~ AS INFLUENCED BY FOUR SUHLlGHT f '" . " > § Z DIFFERENCES AS INFLUEHCED BY --~ ~ 8 MIssoulU AGRICULTIJRAL EXPERIMENT STATION Fig. I-Representative: pOtS of river birch 10 weeks old, alder 14 weeks, and sycamore 15 weeks old grown, from left to right , in oDe-half, one-third, oDe-fifth aod fu ll suolight. Fig. 2- Representative pots of winged dm and American el m l~ weeks old groWD, from left co right, in ODe-half, one-third, one.fifth, :1IJ<! full sunlight. RESEARCH BUllETIN :>n , DISCUSSION AND CONCLUSIONS The gto:wt~ of the seedlings und~r different l!ght intensities has :lp,Pli-cation as:ln mdirect mems of ev:aJu:lung the rebuvely successful esubhsh-ment of:l germin:lreQ se:ed. Furthermore, ir m:ly provide a geneul scale of species toler:lnce. Such a sale may be an indiC:ltor of competitive :lbill[)' of the seedlings with est:lblished uees, and ~rhaps of equal imporunce, of competitive abillty of tree seedllngs with hcrbaceous plants. In :lddition to height growth, an indicative 2nd import2nt growlh response: is the weight of the toors, or the ratio of tOp weight to r()()( weight. This importance lies in the titct thu if, as Knmer and Coile (1940) suggest, root cxtension into the soil supplies a luge part of the ~ter used by a plant, then a poorly developed seedling root system might result in· a localized depletion of soil moisture, brought aboul by a slow eXlension of the root syslem. If the ume species develops a larger root systcm in higher light intensities, seemingly the increased water :lv:lilability resulting from root extension on into new soil ueas is proportionately gre:lter th:ln the iltllount consumed in :md by the :ldditionv top increment. An interpret:ltion of both height growth :lnd top-root ntios of young seedlings of the six species used in this experiment indio.tes th:lt the light tolennce of :llder, river birch, American elm, winged elm, :lnd red m:lple correspond in general to their 5uccession:l1 rebtionships in bottoml:lnd forest communities. Syc:lmore seedlings :lppeu to be at least as shade toler-:me as the elms, despi te the morc :ldv:lnccd 5uccession:l1 rebtionship of the dms. Thus, it is :lppuent th:lt a ruccessiona.l shift to dm-:lSh (and red mapk: in the Piedmont of North u rolin:l) from :l river birch-sycamore level CUI be KCounted for by the low sh:lde toler:mce of river birch, but not syciltllore. Pumam (19:>1) cites river birch and sycamore:ls intolennt, and American elm, winged elm, and red maple as tolerant. Baker (1949) in his poll of Amerio.n foresters found rh:lt rhey regud syc:lmore as tolcnnt, intermedi· ate, :lnd intolerant with emphasis on the btter. To be sure, tolerance tables such as Putnam's and Baker's are based upon all phases of species growth. And, under m:lrure stands of m:lny a.l legedly tolerant spe<:ies (p1rticularly westetn conifers), reproduction of any kind is conspicuously so.rce. Bue, in o.rly suges of primary :lnd secondary succession In bortombnds, then: is reproduction but often of:l more advanced successioll21 stage. This sug-gestS that the :lbsence of very young syo.more seedlings in stands of syca-more successional status, where a canopy is developing, may be due to the development of seedbed conditions thu ate ptohibitive to syomore ger-mination :md immediate establishment of the germinated seed. By the same token, the developmenr of such conditions would be advantageous to the germin:ltion of seed and immedi1te eStablishment of germinated. seed of the maple·elm-uh st:lge. 10 MISSOURI AGRICULTURAL EXPERIMENT STATION SUM .MARY In the successional sequence of bottomland timber species, an early shrub stage often characteriud by alder is replaced by a stage in which sy-camore and river birch may be prominent. This stage in rum, is commonly replaced by a maple-dm-ash community. In general, it can be assumed rhat there is a shift from intolerant to tolerant spt:cies as this alder to sycamore-birch, to maple-elm transition takes place. To test this assumption, very young seedlings of alder, sycamore, river birch, American elm, winged elm, and red maple were grown in four sunlight intensities: full, one-half, one-third, and one-fifth. On the basis of height g rowth and top-root ratios, it was found that alder and river birch are quite intolerant, American dm and winged elm, moderately tolerant, and red maple, tolerant. Contrary to expectations, sy-camore seedlings are at least as tolerant :lS the elms. Thus, the fact that syca-more reproduction is lacking in sycamore stands, and rhat the tendency is commonly tOward elm reproduction, is not primarily due to differences in light tolerance. The sU$8estion is made rhat as succession proceeds in bot-tom land timber areas, n appears that seedbed conditions become prohibi-rive for the sycamore stage and are improving for the elm Stage. RESEARCH BULLETlN ~~7 11 LITERATURE CITED 1. Baker, F. S. 1949. /I rtVistd loin-ana la/;/~. Jour. Foresrry 47: 179-18l. 2. Kr.lmer. P. J. and T. S. Coi le. 1940. /In l$Iimalt of liN "oIU"'t 11/ waltr mad! a~ai(abk byl'llOllxlnuion. Plant Physiol. \5:74)'747. 3. <Josting, H .). 1942. Aif ,ro!;;gi,a! ana/pi! of 1m plam rommunilits of Pi,dmont. North v.roIina. Amer. Midland Nat. 28:J.l26. 4. Putnam,). A. 1951. Malfagtmmt of ""110m/and hardWflods. South. Forest Expr. Sta. OcC1.S. Paper 116: 1·60. 5 Shirley, H. L. 19-B. Ii loln-an(t Ik capadty 10 ."d"" shmk? Jour. ForeStry 41:339-34'. 6. Sreyennark, J. A. 1940. StuditJ of tm wgllation I),f MiJsQ"";-/. Field Museum of NaNI' a] History, Botanical &ories 9: 347-4n. 

Seedling tolerance as a factor in bottomland timber succession

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