f~OREST ECOLOGY AND ~IETTLER~S WOODS

SAl\tt.:Er. T. DA~.-l, Denrt Erneritus · School of .Nalttral Resol1rce:, Univer~ity of l\1icl1igan

~.. ron1 tli.e !'-;ta11d1)oint of the forester, l\'lettler's Woods, 110,v the William L. Hutc11eso11 l\,femorial 1'.. orest, is uniquely ,,aluable as the best re1nai11i,1g example of old-gro,vtl1 oak fore5t 011 the Atla1.1tic seaboard. Tl1is quality gi,·es it di~tir1ction not only as a museum piece b11t eve11 more as an ot1t­ door researcl1 laboratory in ,,·l1ich Nature's 1)1·oces!;eS can he stt1died urider cor1ditions ''°l1ere man's interference is reduced to a mi11imun1. S0111e co11- sideration of the scope a11d aims of forestry ,~ill l1elp to clarify botl1 its pote11tialities and its limitatio11s for this purpose. Definitions of forestry are 11un1erous and not al,vays co11siste11t. l\Ian~· la}·me11 ide11tif}· it with fire fighti11g or tree pla11ting. To son1e f 01·esters it is the gro,-.·i11g a11d harvesting of trees for sa,vlogs or pul1)\\'0od or oll1cr con1n1ercial products. I like to thi11k of it as tl1e scie11ce, the art, and tl1e business of n1a11ag­ i11g fore~ls for tl1e co11tinuous productio11 of goods a11d services. Several co11ce1Jts are packed i11to tl1at brief ~e11te11ce, ,,-l1ich covers a lot of gro1111d. Perl1aps t11e Yer)· fact that f orestr)· has so mar1y facets is 011e of tl1e reasor1s ,.,..l1y there i~ so rnucl1 1nis1111derstat1ding co11cernit1g it.. 111 deali11g '"itl1 so broad a field ,re all le11d to see it from the angle of our o,\.·11 J)erso11al co11• tact \\' i tl1 it. 1"o begin ,vitl1, there is 110 ge11eral agreen1e11l as to ,v hat constitut(~S a ~'forest~! he)·ond the fact tl1at it is a con1n1u11ity in wl1icl1 trees are t\1e domi11a11t Yegetation. Some i11clt1dc i11 the co1l'JJnu11ity 011ly trees and other. ,,·oody ,·egetatioi1, others inc\t1d(.~ all })la11t$~ a11d still otl1e1·s both pla11ts a11d a11imal~. To n1e, it is 111ore realistic to regard a forest as an e.coS}'Slem'. ,,·l1icl1 int\\tdes not only trees, other plants~ a11d a11imals, but aJsl) tlte soil 011 ,v11icl1 a11d in ,vl1icl1 tl1c}· gro,\·. It is a particular kind of la11d area. Vie,red i1i tl1is light, tl1c forest produces a ,\·ide variety of goods and · service~. An1or1g these are wood a11d its in11urnerahle derivatives; otl1er tree })roc111ets ~url1 as naval ~tores~ n1aple syrup~ and rubber; decorative ma­ terials st1cl1 as (:hristmas trees~ ferns, clu}J n1osses, and ,vild flo,..,ers; forage for domestic livestock and game anin1als; wildlife of all ki11ds; modificatio11 l)f tl1e local climate a11d tl1e microclimate; regu1atio11 of the amourtt and distrib11tion of ,,·ater runoff, ,,·itl1 resulti11g influence on soil erosio11 and ~trea1nfiow; 01,portu11it~· for ma11)· fo:rms of outdoor recrea­ tioi1; aestl1etic enjoymc11t; and spiritual ins1)itation. 1'.. orestr~· is J)rOJlerly cor1cer11ed ,\·ith the prodt1ctior1 of a11y or all of these goods a11d services-on a co11ti1111i11g basis. Naturally tl1eir relative i1nporta11ce ,·aries greatly witl1 time a11d })lace. Ra,..,. n1aterials for i11dus- · tr)-! sucl1 as $a,,·logs and JlUlJl\\·ood~ l1a,'e al,\·a~-~ co11$titt1ted tl1e n1ajor J)roclnct cJf tl1e forest in tern1s of direct t111ancial ret11r11s. Tl1is fact, togetl1er ,,·itl1 tl1e fact tl1at ,ve all use lu111her and paper i11 one form or anotl1er, l1as led to t.l1e com1no11 co11ceptio11 that t}1e 1>rodt1ction of ta11gible goods is

36 the sole responsibility of the fore~ter. Actual}}· the i11tangible services relating to soil, ,vater, recreatio11, a11d ir1spi rittio11, ,vhich it i~ cli tlicu lt to express in mo11etary terms, are extren1el1· valuable a11d are tl1orot1ghly deserving of both professional and por1t1lar atter1tion. A friend of mir1e is fond of sayi11g that ,ve coulcl get along reasonably ,vel l \\'itl1out ,fc,ocl httt not '"itbout forests a some1~hat exaggerated but effecti,:e ,,·a~· of en1pl1a• sizing the fact that there are substitutes for ,vood but not for forest i11• fluences. Forest management that aims to J)rodttce se\·eral goods a11d services from the same area is commonly kno,,·n as multiple-use, or 1)1t1\ti-1>urpose, forestry. A national forest, for example~ 1nay simultaneot1:;l:v prodt1ce ,vood, foyage, ,vater, ,vildlife, mineral5-~ a11d recreation, and 111a}· help to clieck ero5ion and floods. Actually tl1ere are ·rery f e,\1 ~orest~ that do not, intentionally or other,vise, serve 111ore than one purpose~ ,,·bate,·er the primary objective of the o,"ner. '\\rel l-ma11aged private f ore:-ts~ for ex­ ample, generally aim to produce co11ti11l1ous supplies of ,,·oologging operations i11 these ,voods a1)cl :-till retuir1 it as a natural area. ,ve can g·ro,v and ltar,·est son1e ,food, forage~ atld ,,·ild­ · }ife 011 the same national forest or J)riYate J>rOJ)ert}·, bttt 11<.lt n1axi111t1m amounts of each. The more ,\'e try to co1nbi11e t1ses, the n1ore- clifl'1ct1lt the task becomes and the more knowledge ,,·e 11eed. These considerations bring 11s to tile heart of forestr~·, tl1at it is essentially a managerial activit}'· lt i11,·ol,·es usir1g-doir1g sor11cthi11g ,v-ith -a forest. ''Use'' con1monly, ht1t 11ot necessarily, n1eans tl1e }1~1r,·esti11g of various crops such as ,v-ood, forage, or ,,·ildlife. But a11 area nianagec1 primarily for protection of the ,vater suppl}', or for ,~ilder11e5~ ,·al11es, or for scientific research is being used jt1st as definitely and co11~tr11ctively in the broad sense oI the term as is an area ,rhich is being n1a11aged for tl1e 11roduction and utilization of sa,,•logs or pulp,v-ood. Tl1e n1a11age111ent of Mettler's Woods as a natural area corlslit11tes a fo1·m of f ore:tr~·~ tl1e pro­ ducts of which are esthetic enjoyme11t. spiritt1al UJ)lift, a11cl ~cie11tific knowledge. · Scientific knowledge is of course a sine qua non for efft"cti,·e forest management. Whatever product the forest manager is seeki11g. lie m11st he thoroughly familiar ,vith tl1e characteristics of the plants, a11irnals, and soi]s comprising the ecosystem and ,vith tl1eir relations to 011e u11other. · Such kno,v]eclge is provided by basic research i11 the biological ar1cl pft}'Si• cal sciences. Its appJicatio11 is a11 art requirir1g a high degree of ~kill. There is often a wide gulf betlveen kno,\·i11g and doing~ het\fee11 basic science and applied science. The most brilliant i11vestigator i~ 11ot a)\\'ays t}te most skillft1I J)ractitiorier.

37 ·ri1 e e 11gi 11ee ri 1,g ~cie11ces are a 11<)tl1er fie Id j 11 ,rh i cl1 the J) ra cti ci i1g forester 111tist l1a\'e some com11ete11ce. ProJ)erL}- hou11darjcs 111t1::;t l)e e~tal>- 1i~l1ed~ tOJ>ogra J)l1 ic 111a J>S n111st 1)e n1ade~ Jlerma11e11t j m J) r<>,'en1e11 ts 1>1 u:-;t. be cor1structed~ aerial J)l1otogra 11l1s rn1,gt J)e i11terJ)rete1ne11l n1ust lle seJecled a11d operated. ,~-l1ere recreatio11 is a,1 i n11)orta11t tl~-e of tl1e forest~ pic11ic aiid camping grou11ds 111t1st he )aid otrt~ a11,J adetyuate J)rO\'i~:io11 n1ade for ~anilatio11 a11d for })rolectio11 f :rom fire. l-'i11al }~·~ eco110111ic considerations ine\·ital)1J· loom Jarge in tl1e fore~t1·y picture. )la11agen1e11t J)factices t11at do not J)roduce 1nore i11con1e t.l1a11 011t• go can11ot be justified. 'fhe relatio11 l)et\\·ee11 costs a11d retu r11~-J)rese11t a11d f utt1re~ tangible a11d intangil)le, JJri\·ate and public-is of vit,11 irn­ portance. }:itller or l)oth are ofte11 difficult to e:XJ)ress i11 dollars and cer1t~, l)ut so111e ,·aJue mu~t l)e r)laced u11on then1. Ho,\· mucJ1 d(J eroded hillsicles a11d fire-~carred land~caJ)es C<>st? ,x:hat are super}) sce11ery a11d a J)ltre ,\·ater SUJ.'J-,1~· ,\ ortl1? Is t)1e fi11a11cial ret11r11 lost Jly failure to Jog tl1is forest n1ore tl1a11 off~et by the i115J)iralio11 a11d tl1c scientific k110,\·ledge tl1at ,rill re5uJt from keeJJing it as a 11alt1ra1 area? Questio11s like ll1e~e 111ust })e a11s,vered l1}" the judgn1ent· of the con1- 111unit}· as to tl1e relatire ,:a)ues i11,,0J,·ed. '\'\'e are accusto1l1ed to makir1g Sl1cl1 jt1dg1ne11t~ \\'ill1 re~1)ect to cit)r J)arks~ J.)Ublic libraries~ art gallerjcs, scl100 Is~ a 11d c J1urche:-. \\Te must get u~ed to n1a ki 1•g tJ1e111 ,,. i tl1 reSJ>ect to forests a11d otl1er r1att1ra 1 resot1rces. Ho,r the com111ur1it,, ca11 l:iest ol>li.ti11 lhe ,-alt1e5 it decides it ,vanls raises imr1orta11t ri,-ate o,f11er~l-1i1> acl1ieve the desired results ,\'itl1 J)til)lic co­ operatio11 a11d co11trol '? 111 the case of l\1etller~s "i oocls, tl1e a11s,\1Cr -l1as bee11 f ou11d i11 Jlt1ll] ic o,, 11er~l1iJJ 1J)" a,1 educatio11a I i11~tit11tion. All of tl1is bri11gs 1ne back to my origi11al thesis tl1at forestr}· is a n1a11agerial ac:tivity i11,·olvi11g scie11ce, art, a11d l)usiness. I.... ikt! (>tl1er for111s of la11d 111a11a2'e111e11t,. it uses so1111d tech11o}ogica}~ practices to achieve ccr- tai11 de~ired eco11on1ic a11f tl1e l)iological scie11ces, the J)l1)·sical a11d e11gi11eer.ing sciences~ and tile social scie11ces. Tl1e co11trillt1tio11 ,\·hicl1 tl1i5 f <.lrest ca11 1nake to strengtl1e11i11g tl1at fo1J11- cJatio11 clearl~· lies i11 tJ1e field of tl1e l1iological scie11ces. and 1nore si,ecifi­ callJ· i11 t11e ~cie11ce of ecology. Thi~ is J)artl}· ])ecatrse of tl1e i,1tri11sic i1n­ J)Orta11ce of ect)log-~-~ lltJt e,·e11 1nore l)eeau~e of tl1e suita)Jilit)" of the area for studit'S i11 that })articular subject. It i!:1 a1so i11e\'italJle tl1at ecological re£-ea reh ,r i 11 exte11d i11t o tl1e close I)' re:-lated fie] ds of r>hJ0 siology a11d ge11etlCS.• Si11ce tl1e J:>1·udt1etio11 of f ore~t c1·ot)S~ ,rl1etl1er tr<-'es~ forage~ or ,,·ild• life. i:5 guiti<'<~ ~o lar~t,J~- l)y r.<·()lo:1ical fact~ a11d r,ri11ci1>le:-~ tl1ere i.lJ>J1eats to 1J<> a gro,\ ing te11c.le11c~' tc> co11~icler fr,re~tr)· .ts 110~}1i11g 111,)re 11or l-.:'i>S tl1a11 BJJJllied ecolog)·. Tl1is is goi11g too far. ,1·J1ile it is ut1qt1e:,;tio11al1ly true tl1at forestr)· 8J)J)lie~ ecolog)·~ jt also B(lt>lies 1)atholog.)· at1d e11to11101-

38 ogy a11d mathematics at1d e11gineering and ecoriomics. lf 011e thinks 011ly of timb~r production~ it is e11tirel}· llfOJ>er to regard ecology as or1e of the mai11 fou11datio11s for silviculture~ ,rhich is the art of re1)roduci11g a11d tending the timber crop. B11t sil,.-ic11lt11re is only one of the fi"·e fields i1l ,vhich the Society of •.i\mericat1 F ore~ters belie,..·es a forester 1nL1st ha,·e adeq11ate tt>ch11ical trai 11 i11g to hf' recog11ized as J>rof t.•~:;io11a l l y co111 J)ete11t. 'fl1e other fields are f ort'sl Jlrotectio11, forest n1a1lagen1e11t, forest utiJ iza­ tion~ a11d forest economic~, ,\·hich ob,·iously go far beyonc.--1 the bo1111ds <)f ecology. Tl1at the Hutcheson J:'orest mai11tai11ed as a r1at11ral area can co11• tribute substa11tially to our k110,vledge only in the silvicultural field i11 110 ,vay minimizes its ,·al11e from the ,·ie,vpoir1t of the forester. Tl1is is tr11e i.11 Sflite of tl1e fact that a forester·s acti,,ities are so ofter1 concerned ,vitl1 moclifyir1g natt1ral cor1ditio11s. :\!other I\ature if left to herself seldom produces maximt1m forest crops a11)· more than sl1e J.lrod11ces n1aximt11n agricultural crops. It is rather c11rious, ,,·hen ,ve are all so familiar ,,·itl1 tlie drastic ,...-a).- in '"·}1ich farming i11terf eres wit}1 natttral processes. that ,..-e sho11ld not recog11ize the desirabilit}· of si1nilar interference i11 the mar1agement of forest la11ds. No one recommer,cls maintai11i11g tl1e '~}Jal­ ance of nature'' in the J)rocommunity as a ,vhole remai11s aJlJ)roximately the san1e. Unfortunately, fron1 some J>Oints of vie,v, the clin1ax stage in a natural succession of forest tyJ)es is often 11ot the one best adapted to man's i1tilitarian needs. Commonl}· tl1e earlier stages i11 st1ccessio11 have greater economic or e,·e11 greater recreational val11e. In the field of timber prodt1ction, for example, ,,.-hite pine i11 Ne\\-' J.~r1glar1cl, as1let1 i11 the Lake States, longleaf pi11e in tl1e Sot1th. ,,·e~ter11 ,v l1ite ()i11e i11 the 11ortl1er11 Rocky l\1ountains, and Douglas fir i11 tl1e IJacific Nortll\\'est are ,·al uable commercial species ,\·hich the forest ma11ager often ,-\"isl1es to perilett1ate. Yet these are all temporar~- forest t)·pes, or in 1nore tech11ical tern1s '~s11ll- c l1maxes. '' or ''d 1sc· 1 1maxes· ·· . In the field of ,,·ild life 1na11ageme11t, deer i11 11ortl1er11 :\iichigar1 are far less abundant in an unbroken climax forest of norther11 l1arcl,voods than in areas where numero11s OJ)enings create a11 ''edge effect'' tl1at proYicles a more favorable hal)itat. The reclamatio11 of open fiel(ls b~- forests 1nay completel}· eliminate 5t1ch birds as the J>rairie cl1icke.t1 a11d the sl1arJl· tailed grouse. l11 the realm of ,rater:;hed n1anageme11t, rece11t studies in tt,e Rocky l\-1011ntains ha\·e ~lro\rn that the y.ield of \.vate-r is less f ro111 clense stands of lodgeJlO le 1>ir1e tl1a11 f ro111 forests in ,vhicl1 l1oles or strips

39 l1a,,e bee11 cut to reduce tra11spiration a11d tl1e i11lerceptio11 of preci1)ita. tio11. These openi11gs result i11 tl1e maxin1111n accumulation of s110,v, fro1n · \\"l1ich the bulk of tl1e runoff is derived. Tl1ese examples of the ,•alue to man of transitio11al seral stages do 110.t. of course imply tl1at he is never i11terested i11 tl1c c1imax forest com•munity. Norther11 hard,oV"oods in the Nortl1eastern and Lake States, ponderosa pine on dr}· sites throughout much of the West, and redwood in Califor11ia are iJlustrations of climax forest types tl1at the forest manager usually ,,·ishes to perpetuate. The important point is that '"'hene,·er man ir1tcr• feres ,vith natural processes, as by ]oggi11g or hu11ting, he n1ust kno,\' ,,,J1at results he seeks and ho,v they can best be acl1ieved. Among other thi11gs, this requires eco1ogical knowledge of a l1igh order an.d skill i11 its application, particularly \\ihen the ol)jective is to n1aintain a tetnJlOf· ary stage in the 11ormal ~ucce.ssio11. Ho,v can natural areas help to SUlJllly tl1e rteeded kno,,·ledge ,-vhet\ by defi11i'tion the)· are to be reserved frorn co1111nercial utilizatio11? ·1•11e a11s,.,·er is that i11 order to modify 11atural 11rocesses successfulJy ,ve 1nust first kno,v ,\That tl1ose Jlroces~es are. I11cide11tally it may }Je ,•;ell to 11oi11t out tl1at the Hutcl1eso11 Forest is 11ot 100 per ce11.t natural~ since the cle;:1r• i11g a,\·ay of the surrot111di11g forests, i-eJ)eated n1an-caused fires, and tI1c Jogging of ,vindfalls after tl1c 1950 l1urricane l1ave n1odified 11att1ral co11• ditio11s i11 the tr11ct. Furtl1ermore, from no,v 011, sufficient manage111e11t \vill pre~un1ably he practiced to prevent serious damage to the forest l)y fire, insects, or disease. Co1npared ,'\'ith other areas i11 tile region, }1ow­ e,,er, tl1e tract re1)resents, and 1.111der the direction 0£ Rutgers University \\'ill co11tinue to reJ)rese11t, the closest aJJproacl1 to natural conditio11s \Vhicl1 it is feasible to attai11. Herein lies its greatest value. In an u11dist11rbed forest one ca11 ol)tai11 mucl1 i11f or111ation 11ot avail· al)le else,~here c-01)cer1ling the normal i11terrelations that exist betlvcer1 trees, sl1rul)s: l1erl)s, fungi, i11sects, birds, man11nals, eartl1\\'orn1s, nen1a­ todes, soil, alld climate. Only in an undisturbed forest can 011e determi11e v.·hetl1er tl1e prese11t sta11d of oak anll hickor)· is really a climax comm1111ity or ,vl1etl1er it ,vill i11 time be replaced by a stand ir1 ,,..,}1jch n1aple and beecl1 are predominant. \-et sucl1 infor1nation is indispe11sallle for tl1e forest ma11- ager, particularly if })is objective is, so to speak, to ''buck'' Nature. 1ian can11ot co11quer Nature in Ll1e se11se tl1at he e,•er changes natural la,-.s. He ca11~ l10We\·er, a1ter materially and st1ccessf ul ly tl1e 11atural co11rse of events if l1e k110\,·s ,,,hat those laws are and governs his activities in accord­ ance ,-;ith tl1en1. Tl1e need· for ,,·isdo1n in the ma11ageme11t of forest Ia rids is emJJlta• sized h)' tl1e 1011g life of tl1e trees ,vhicl1 are the domina11t ele1ne11t i11 tl1e · co1nmu11it}'·. Dea11 (;, S. Al le11 of the F'act1lty of :i:·ore~tr)· at tlie Universit)· ,Jf Briti~l1 Co111mbia rec-e11tly expressed as follo"·s tJ1t' solJeri11g rei-J)Or1~i­ JJi)ity '"J1icl1 tl1e forester mu~t face: '~\\7}1at ,,·e do tc1day a,1d tomorro,,' \\:ill affect generatio11s to come fa,,orably or 11nfavorably. We do not kno,\' e11ough )·et to ,vork in com1>lete harn1ort)· with Nature, and so l,·e ,\

40 ingly conservative in the biological sense and follo,\i Nature as closely as \-.·e can''. (Allen, 1955). Dean Allen ,vas speaking specifically of silviculture, or tin1ber pro• clt1ction. but thoro11gh kno,vle(lge of 11att1ral processes i.s also 11.eccs~ary to obtain optiml11n retur11s in otl1er fields such as ,vatersl1ed manage1ne11t and recreation. Generally speaking~ the more ""·e kt10,v the more liberties '\\ie can take in modifying the environment to n1eet .1nan's needs. l\tluch can he learned from controlled experiments in disturbed areas, ,vhich ,vill of course continue to be '\fidely used for research purposes. T}1ey are, however, not a substitute for undisturbed areas, ,,·here studies of natural processes ,viii help us to direct our managerial activities along sound lines. Tl1at foresters recognize these trutl1s is sho,vn by the fact that for many years the Society of American Foresters has had a Committee on .Natural Areas, and that that con1mittee partici1)ated active])· in the cam• ·. paign to preserve these ,voods from tlestruction. How does forest ecology differ from a11y other kind of ecology? If, as I stated earlier, the forest is the entire ecosystem, then forest ecology· is all-inclusive i11 its st1.1dy of er1vironmental rela.tions. Tl1ere is no aspect of the inter-relations between tl1e pla11ts and animals in tl1e fo1·est ai1d · the e11vironment i11 '\\lhich tl1ey live, ,\"ith ,vhich it is not concerned. Con1i11g from a forester, this statement ma)• so11nd immodest, l)ut I belie,'e tl1at it is realistic. No one ,vould den}• that in ecology as in ot}1er l,ra11cl1es of biolc>gy ,ve need specialists. The other speakers today ha,,e de1nonstrated u11111is­ takahly the services that can be re11(Jered lJy plant ecologists a11d anin1al ecologists and soil ecologists. Some of tl1ese men ,,·ill do11l)tless ,rork i11 still n1ore specialized fields such as n1oss ccolog}· a11d i11sect ecolog}· a11d mammal ecology. In these days ,,·hen ,ve are ex1>anding tl1e bot111daries of knowledge so far that it is necessar}· for most scie11tists to k11g~· deal ,ritl1 all

41 as1>ects of the 11\ler-relatior,s l>e\\,·een tl1c trees-, other 1)la11ls, a11in1al~, u.t1d e11vironn1c11t that co1nJlrise the e.coS)'~te1n. It is cl1aracterized both l,y its broad sco1le and hy tl1e utilitaria11 cha1·a~ter of its \1ltimate ol)j(~eti\"e . •.i\.ltl1ougl1 recognizi11g the ir1dis1)er1i:;al)ility of basic researc}1, it is c1Jm­ n1011ly less il1tereE--ted in k110\,·ledge as at1 e11d i1, itself tl1a1, as a n1e.a11s to an e11d •. That e11d is the co11tir1uou.s J)roductio11 a11d use of goods a11d ~erv­ ices, an1ong ,,·l1icl1 \\"ood a11d fore~t i11ilue11ces ,,·ill doul)tless coriti1,\1e tate i11 tl1c 11rograms tl1at ,,·ill be de,·elopc,J at the H utcl1e~o11 l•~orest. \X"ithin the l irnitatio11s irnJ}osed by its relatively sinall size a11d uniforrn co11di­ Lio11s, it offers u11usual opport1~11ities for ad,,a11cing our k110,vletlge ii1 ecology and related fields. It ca11 thus be a n1ajor asset in J)lacing one as1)ect of forest manageme11l i11 tl1e hard,food regio11 of Ne,v- Jersey a.rid at-ljace11t states 011 a firmer fou11dation tl1a11 ,,·ould otl1er,,·ise be })Os~i})le.

I co11gratulate Rutgers U11i,·ersity on tl1e acqui~itio11 (Jf so u11ique a11cl so ,·aluable a J)rOJlert)'· I·~orestcrs ,vill f ollo,v ,,·itl1 keenest i11lert~:-;t tl1e research that Vfil I he co11dtiCtt'd tl1ere a11d ,,·il I take adva11tage 1r1 tl1eir o,-v11 acti,·ities of tl1e results ohtai11ed.

J~l T ER:\TURE CITl-:tl

Allet1, G. S. 1955. Estal)li~l1ing tl1~ 1:rO}l. 1'"'or~~1.r"y Cllrorricle 31 :31-34-.

4.2