Heusser, 1990, Tagua tagua (1)

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Palaeogeography, P alaeoclimatology, Palaeoecology, 80 ( 1990): 107-127 107Elsevier Science Publishers B .V., Am sterdam

I c e a g e v e g e t a t i o n a n d c l i m a t e o f s u b t r o p i c a l C h i l eC . J . H e u s s e r

D e p a r tm e n t o]" B io lo g y , Ne w Yo rk U n ive rsi ty , 1 0 0 9 M a in Bu i ld in g , Ne w Yo rk , N Y 1 0 0 0 3 (U . S .A . )(Re c e iv e d O c to b e r 3 , 1 9 8 9 ; r e v i se d a n d a c c e p t e d A p r i l 1 7 , 19 9 0)

A B S T R A C THeusser, C. J.. 1990. Ice age vegetation and c limate of sub tropic al Chile. Palaeogeogr., Palaeoclimatol., Palaeoecol., 80:107- 127.

Vegetation a nd climate of sub tropica l Chile over the past > 50,000 yr are reconstructed from pollen, spores, and o thermicrofossils contained in a 10.7-m section o f lacustrine depo sits of Laguna de Tagu a Tag ua (34~30'S, 71 10'W). Co ntrolled by14 radio carb on age determinations, five pollen assemblages covering stratigra phic zones in the section represent plants on theupland and species inhabitin g the lake basin. Surface pollen spectra from 58 stations (approxim ately 30 -4 0S ) form an adjunctfor interpreting past vegetation an d clim ate from the fossil record.Temperate, semi-humid woo dland of southern beech (Nothofi~gus dom beyi type) and podocarp (Prumnopitys andina) w asapparently established about Laguna de Tagua Tagua during the Pleistocene. Contrasting existing semi-arid, broadsclerophyllous vegetation, the woo dland was extensive about the lak e at the t ime of the last glacial maximum (25,000-14,000 yrB.P.) and ea rlier (> 43,000-34,000 yr B.P.). Pollen from the fam ilies Chenopodiaceae and A mar anthac eae, which characterizeintervals of the Pleistocene (centered arou nd 33,000 and >43,000 yr B .P.) and the Holocene, suggests intervening episodes ofrelative aridity. Lake level fluctuations a ppe ar to follow the late Qu aterna ry climatic patte rn implied by pollen assemblage data.W ater in the lake was relatively high during development o f southern bee ch- po doc arp woodland, w hereas during intervals ofchen opo d-am aranth dominance , lake leve ls were compara t ive ly low.Excess precip itation over evap oration , which during the Pleistocene favored development o f woodla nd of beech andpodocarp, is attributed to greater storm frequency. Conditions were apparently governed by strengthening of atmosphericcirculation in the belt of southern westerly winds. In the late-glacial, the tem perate and mo re humid, ice age climate with l imitedseasonality underwent transit ion to a subtro pical, semi-arid, M editerranean type that identifies the postglacial . Flu ctuatio ns inintensity of the southern westerlies, ma rked by la ti tudin al movement of the pol ar front, can account for past vegetation changesa t Laguna de Tagua Tagua .

I n t r o d u c t i o nG l a c i a l d e p o s i t s in t h e A n d e s M o u n t a i n s , e ra -

p l a c e d d u r i n g t h e P l e i s t o c e n e by w i d e s p r e a da d v a n c e s o f g l a c i er s ( C l a p p e r t o n , 1 98 3 ), a t t e s t toi c e - ag e c l im a t e i n c o n t r a s t w i t h t h e p r e s e n t .C l i m a t i c c o n d i t i o n s w e r e a p p a r e n t l y c o l d e r a n dm u c h s n o w i e r t h a n t h e y a r e t o d a y . A t 3 3 S i n t h es u b t r o p i c a l A n d e s o f C h i l e - A r g e n t i n a , g l a c i er s a tp r e s e n t a t a l t i tu d e s o f > 4 5 0 0 m h a d d e s c e n d e d t oa r o u n d 2 8 0 0 m d u r i n g t h e la s t g l a c i a t i o n ( C a v i e d e sa n d P a s k o f f , 1 9 7 5 ; C o r t e a n d E s p i z t ~ a , 1 9 8 1) .P r e s e n t - d a y c l i m a t e i n t h e h i g h c o r d i l l e r a a t t h isl a t i t u d e ( C r i s t o R e d e n t o r , 3 2 5 0 'S , 3 8 2 9 m ) , b yc o m p a r i s o n , i s s t r ik i n g l y d r y w i t h m e a n a n n u a l

p r e c i p i t a t io n m e a s u r i n g o n l y a b o u t 3 50 m m( M i l l e r , 1 9 7 6 ) .

F e w p a l a e o e c o l o g i c a l d a t a b e a r i n g o n t h e cl i-m a t e a n d v e g e t a t i o n o f t h e la s t g l a c i a t i o n a r er e c o r d e d f r o m s o u t h e r n S o u t h A m e r i c a ( H e u ss e r ,1 98 7 ). A t h i g h e r l a t i t u d e s , w h e r e g l a c i a t i o n c r e a t e dd e p o s i t i o n a l b a s in s , m o s t r e c o r d s a re f r a g m e n t a r yo r b e g i n a f t e r l a t e - g l a c ia l w a s t a g e o f t h e i c e, a sg l a ci e rs p u l le d b a c k i n to t h e A n d e s M o u n t a i n s .O n l y r a r e l y i n t e m p e r a t e s o u t h e r n C h i l e , a s o n I s laG r a n d e d e C h i l o 6 ( 4 2 S ) , d o e s a r e c o r d ( V i l la g r~ m ,1 98 8) e m b r a c e t h e m i l l en n i a o f m a x i m u m g l a c i a -t i o n . C o m p a r a b l e s i te s f o r e s t a b l i s h i n g t h e e n -v i r o n m e n t a l s e t t i n g a t l o w e r s u b t r o p i c a l l a t i tu d e sd u r i n g t h e i ce a g e a r e e q u a l l y r a r e .

0031-0182/90/$03.50 ;~:~, 19 90 Elsevier Science Publishers B.V.


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108 c.J . HEUSSERL a g u n a d e T a g u a T a g u a , i n t h e i n t e r i o r c e n t r a l

va l l ey o f sub t rop ic a l Ch i le , is the on ly r eg iona ls o u r c e o f c o n t i n u o u s v e g e t a t i o n a l a n d c l i m a t icd a t a f r o m b e f o r e t h e l a s t g l a c i a l m a x i m u m . I t sl acus t r ine depos i t s , w i th the i r m acro fos s i l andm icro fos s i l con ten t (Casam ique la e t a l . , 1967 ;Vare la , 1976 ; Heu s se r , 1983), p rov id e a un iqu ein te rp re t ive base fo r as s es s ing the vege ta t ion andice age cond i t ions no t on ly a t low a l t i tude bu t a l soin the h igh co rd i l l e r a . I t s l a t e -g lac ia l pa leo - Ind ianrecord (Mo ntan6 , 1968 , 1969) i s one o f the ea r l i e s ti n s o u t h e r n S o u t h A m e r i c a . T h e p u r p o s e o f t h ispaper i s to desc r ibe and in te rp re t the fos s i l r eco rdo f L a g u n a d e T a g u a T a g u a , e m p h a s i z i n g i ts p o ll e na n d s p o r e s t r a t ig r a p h y i n t h e c o n t e x t o f th e p a s tenv i ronm en ta l s e t t ing .Subtropical Ch ilePhy s i ography and g l ac i a ti on

S u b t r o p i c a l C h i l e ( F i g . l ) l i e s r o u g h l y n o r t h o ft h e l a ti t u d e o f C o n c e p c i 6 n ( 3 6 5 0' S ) a n d s o u t h o fL a S e r e n a ( 2 9 5 5 ' S ) . T o p o g r a p h i c f e a t u r e s i n l a n df r o m t h e P a c i f i c O c e a n a r e t h e C o a s t a l M o u n -t a i n s , C e n t r a l V a l l e y , a n d t h e A n d e s M o u n t a i n s .C o n s i s t i n g t o a g r e a t e x t e n t o f l o w h i ll y te r r a i n o fM e s o z o i c g ra n i ti c a n d o l d e r m e t a m o r p h i c r o c k s(Br f iggen , 1950 ; Ze i l , 1964) , the Coas ta l Moun-t a i n s r i s e n o r t h w a r d i n a l t i t u d e f r o m a f e wh u n d r e d t o > 2 0 0 0 m . D i s s e c t i n g th i s u p l a n d a n dc r o s s i n g t h e C e n t r a l V a l l e y , a n i n t e r c o r d i l l e r a nd e p r e s s i o n u n d e r l a i n b y Q u a t e r n a r y s e d i m e n t s , i sa s u c c e s s i o n o f d r a i n a g e s y s t e m s o r i g i n a ti n g i n t h eA n d e s . T h e A n d e s M o u n t a i n s t o t h e e a s t, f o r m e db y M e s o z o i c a n d C e n o z o i c s e d im e n t s a n d v o l c an -i c s , a r e a t a l t i t u d e s > 2 0 0 0 m w i t h s u m m i t sb e t w e e n 3 2 - 3 4 S r i si n g t o > 6 0 0 0 m . T h e s e s u m -m i t s , w here the f i rn l ine i s a t a bo u t 4500 m , a reo c c u p i e d b y a n u m b e r o f s m a l l v a l l e y g l a c i e r s ,w h i c h h a v e b e e n r e c e d i n g o v e r a l l d u r i n g r e c e n tcen tu r ies (L l ibou t ry , 1956 ; Cor te and Esp iz f l a ,1981 ; Su~ trez , 1983; Cob os an d Bon insegn a , 1983 ;Espizf la , 1986) .

G l a c i a t i o n o f t h e s u b t r o p i c a l C h i le a n A n d e sdur ing the P le i s tocene r eached a l t i tudes as low as120 0m (San tana-Ag u i la r , 1973); g lac ia t ion tolower a l t i tudes in the Cen t r a l Va l l ey , based on the

e v i d e n ce o f d r if t- li k e d e p o s i t s f o r m e d b y m u d f l o w s ,i s now d i s coun ted (S eger s t rom e t a l ., 1964 ; M ac-Pha i l , 1973 ; Vare la , 1976). Dur ing the l a t es t o fth ree g lac ia t ions , an advance in the ne ighborhoodo f A c o n c a g u a ( F i g . l ) t h a t r e a c h e d a s lo w a s2800 m dur ing the l a s t g lac ia l m ax im um (Cav iedesand Paskof f , 1975) i s co r re la ted w i th an adv ance o fthe s am e g lac ie r sys tem in Argen t ina , ou twashf rom which i s da ted a t 10 , 000 y r B . P . (Bengocheaet al. , 198 7; Espiz fla, 1989).Climate

C l i m a t e o f s u b t r o p i c a l C h i l e i s h o t a n d d r y i ns u m m e r , w h e n t h e r e g i o n c o m e s u n d e r t h e d o m i -na t ing con t ro l o f the Pac i f ic an t i cyc lone . In f lu -enced by f ron ta l sys tem s o r ig ina t ing in thesou the rn wes te r li e s , i t is coo l and r e la t ive ly we t inwin te r . C l im at ic da ta fo r s t a t ions a t low a l t i tudes(Tab le 1 , F ig . l ) ind ica te m e an t em pera tu re s o fa p p r o x i m a t e l y 1 8 - 2 1 C i n s u m m e r a n d a r o u n d8-12C in w in te r ; to ta l annua l p rec ip i t a t ion i sb e t w e e n 1 0 0 - 8 0 0 m m w i t h 8 4 - 9 0 % f a ll in g d u r in ga u t u m n a n d w i n t e r .

Coo l a i r , m ov ing in land f rom the Pac i f i c Ocean ,o rograph ica l ly lo ses i t s m o is tu re on c ros s ing theCoas ta l Moun ta ins , l eav ing the in te r io r va l l eysrelat ively dry (Mil ler , 1976) . Precipi ta t iona m o u n t i n g t o a b o u t 8 00 m m i n t h e v i c in i ty o fL a g u n a d e T a g u a T a g u a c o n t r a s t s 1 2 00 m m t o th ew e s t o f t h e C o a s t a l M o u n t a i n s a n d 2 5 0 0 m m a tth i s l a t i tude on the Pac i f i c s lope o f the Andes(Alm eyda and S~ tez , 1958). Fo g an d low s t r a tusc l o u d s a r e a c o m m o n f e a t u re o f t h e c o a s t a l s e c to rin the no r the rn par t o f the r eg ion .

A s o u t h w a r d t r e n d o f in c r e a si n g s u m m e r p r e c ip -i t a t ion i s apparen t in the da ta (Tab le 1 ) , shown a tt h e l a ti t u d e o f C o n c e p c i 6 n a n d a t s t a t i o n s f a rt h e rsou th (F ig . 1 ), where sum m ers a re inc reas ing ly we t .T h i s c o n d i t i o n i s b r o u g h t o n b y g r e a t e r c o n t r o l o fthe po la r m a r i t im e cyc lon e , r esu l t ing in an inc reaseo f s to r m f r e q u e n c y a n d C l ou d c o v e r t h r o u g h o u t t h eyear . A t l a t i tude 40S , annua l p rec ip i t a t ion in -c r e a se s t o 1 3 0 0 - 2 5 0 0 m m a t l o w a l t i tu d e s ( 4 0 0 0 -5 0 0 0 m m i n t h e m o u n t a i n s ) a n d m e a n t e m p e r a t u r e sf a l l t o 1 5 - 1 8 C i n s u m m e r a n d 8 - 9 C i n w i n t e r .T e m p e r a t u r e s b e t w e e n t h e l a t i t u d e s o f S a n t i a g oa n d P u e r t o M o n t t u s u a l l y v a r y b y o n l y 1 - 2 C


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ICE AGE VEGETATION AND CLIMATE OF SUBTROPICALCHILE

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- s u c c u l e n t v e g e t a t i o n

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F i g . 1 . M a p o f s u b t r o p i c a l ( 3 0 3 7 S) a n d a d j a c e n t t e m p e r a t e C h i l e s h o w i n g l o c a t i o n s o f L a g u n a d e T a g u a T a g u a , p h y s i c a l f e a tu r e s ,p l a n t f o r m a t i o n s ( S c h m i t h f i s e n , 19 56 ), a n d p l a c e s w h e r e m e t e o r o l o g i c a l d a t a a r e a v a i l a b l e (T a b l e 1 ) .

dur ing the r a iny w in te r s ; in sum m er , d i f f e rencesa m o u n t t o 3 - 5 C ( T a b l e 1 ) .Vegetation

R e g i o n a l n a t u r a l v e g e t a t i o n o f t h e i n te r i o rva l l eys and low h il ls o f sub t rop ica l Ch i le (F ig . l ) i sc h a r a c t e r i z e d b y b r o a d s c l e r o p h y l l o u s w o o d l a n d

o r m a t o r r a l ( S c h m it h fi se n , 1 9 5 4 , 1 9 5 6 , 1 9 6 0 :O b e r d o r f er , 1 9 6 0 ; M o o n e y , 1 9 7 7 ; T h r o w e r a n dB r a d b u r y , 1 9 7 7 ; A r m e s t o a n d M a r t i n e z , 1 97 8) .Supp lan ted by ex tens ive f a rm ing in the va l l eybo t tom s , wh ich were l a rge ly s e t t l ed beg inn ing int h e 1 9 t h c e n t u r y , t h e w o o d l a n d c o v e r s m o u n t a i ns l o p e s t o a m a x i m u m a l t i t u d e o f 1 6 0 0 m . I t sl a t i tud ina l and a l t i tud ina l r e la t ionsh ips a re w i th


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11 0T A B L E IC l i m a t i c d a t a f o r s e l ec t e d s t a ti o n s i n s u b t r o p i c a l a n d t e m p e r a t e Ch i l e"

C . J . H E U S S E R

S t a t i o n Av . t e m p e r a t u r e(of)

Av . p r e c i p i t a t i o n( m m )S e a s o n a l d i s t r i b u t i o n ( % )

S u m m e r W i n t e r A n n u a l S p r in g S u m m e r A u t u m n W i n t e rSubtropicalLa Sere na (2955'S) 18.3 11.7 110San t i ag o (3327 'S ) 20 .6 8 .0 360San Fe r nan do (3435 'S ) 20 .0 7 .5 780TemperateCo nce pci 6n (3650 'S) 17.8 9 .1 1338Va ldivia (3948 'S) 17.1 7 .8 2510O sorn o (4033 'S) 17.6 8 .3 1330Pto. M on tt (4128 'S) 15.3 7 .6 1960

8 2 22 6815 3 2 4 5814 2 25 59

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"Almeyda and S~ez (1958) .s e m i - a ri d t h o r n s h r u b - s u c c u l e n t v e g e t a t io n , e s ta b -l i sh ed t o t h e n o r t h , an d d ec i d u o u s b eech fo re s t ,l y i n g mo s t l y t o t h e so u t h (F i g .2 ) .O w i n g t o p r e c i p i t a t i o n a n d t e m p e r a t u r e g r a d i -e n t s a n d a h u m a n d i s t u r b a n c e f a c t o r , b r o a dsc l e ro p h y l l o u s wo o d l an d d i f fe ren t i a t e s o v e r t h ee x t e n t o f t h e r e g i o n . C o m m u n i t i e s t y p i f i e d b yCryptocarya a lba ( L a u r a c e a e ) c o n t a i n , i n a d d i t i o n ,t h e a rb o rea l sp ec i e s Schinus lati folius ( A n a c a r d i a -ceae ) an d P e u m u s b o l d u s ( M o n i m i a c e a e ) a n d i nc l o u d - c o v e r e d p a r t s o f t h e c o a s t , Bei lschmied ia

miers i i (Lau raceae ) . Co mmu n i t i e s i n re l a t i v e l y d ryl o ca t i o n s a re d i s t i n g u i sh ed b y L i th ra e a c a u s t i c a( A n a c a r d i a c e a e ) a n d i n c lu d e , in a d d i t i o n t o Cry p -toearya a n d P e u m u s , t h e o v e rs t o ry sp ec ie s Quillajasaponaria a n d Kageneck ia ob longa (Ro saceae ) . Th et ree M a y t e n u s b o a r i a (Ce l a s t raceae ) i s g en e ra l l y o fm i n o r i m p o r t a n c e b u t w i d e d i s t r i b u t i o n i n t h eL i t h r a e a - d o m i n a t e d c o m m u n i t i e s .

A l a r g e s e c t o r o f t h e d r y i n t e r i o r b e t w e e n t h eC o a s t a l M o u n t a i n s a n d t h e A n d e s a t t h e b o r d e r o fb r o a d s c l e r o p h y l l o u s w o o d l a n d i s o c c u p i e d b y

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- - T h o r n S h r u b ~ ~ ~ " \ . \ \ \ \ \ \ . ~ \ ~ . m .S u c c u l e n t f ~ N . ~ .~ . ~ - ~ \ \ \ ~ ~ \ ~ \ ~ I r 1 - 1 0 o o_ _ V e g e !a t io n ~ ~ / / ' o ~ . ~ . / V . ~ /~ . ~+': i2+;i i , -i i : i i+++ : i'~5i5575i: ; :2+2~ ~' ' '~i i~ ~+

320 3'30 3'40 i 3'5 3'6 3'7 3'B 3'9 4'0 4'1Broa d Sclerophyllous Woodland (matorra l ) Decidu ous Bee ch Fore stIL a g u n a d e T a g u a T a g u a

F i g .2 . P l a n t f o r m a t i o n s o n t h e we s t s l o p e o f t h e An d e s M o u n t a i n s s h o wn i n r e l a t i o n to L a g u n a d e Ta g u a Ta g u a . F r o m S c h m i t h f i s en(1960) wi th some mod i f i ca t ion .


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I CE A G E V E G E T A T I O N A N D C L I M A T E O F S U B T R O P I C A L C H I L E 1 1 1

s t e p p e - s c r u b o r e s p i n a l . F e a t u r e d a r e t h e s h r u b sTrevoa t r inerv i s ( R h a m n a c e a e ) , Col l iguaya odor i -

f e r a ( E u p h o r b i a c e a e ) , a n d C e s t r u m p a r q u i ( S o l a n a -c e a e ) , a n d g r a s s e s (Nasse l la ch i l ens i s ) a n d c o m p o -s i tes (Gu t i e r r e z ia p a n i cu l a t a ) . C o n t a i n i n g s c a t t e r e df l a t - t o p p e d t r e e s o f A ca c i a ca ven ( M i m o s a c e a e ) ,t h i s v e g e t a t i o n h a s b e e n m u c h d i s t u r b e d b y m a na n d g r a z i n g a n i m a l s a n d is c o n s i d e r e d t o b e p a r t o fa s u c c e s s i o n a l s e r i e s l e a d i n g t o w o o d l a n d ( O b e r -d o r f e r , 1 9 6 0 ) .

C o l o n i e s o f N o t h o f a g u s ( F a g a c e a e ) , o u t l i e r s o fs o u t h e r n b e e c h f o r e s t t o t h e s o u t h , r e a c h n o r t h e r nl i m i t s i n t h e m o u n t a i n s ( F i g . 3 ) . A t r a n s e c t m a d eb e t w e e n t h e o c e a n a n d t h e A n d e s a t 3 4 5 0' S , c l o s et o L a g u n a d e T a g u a T a g u a , s h o w s t h e l o c a t i o n o fd e c i d u o u s N o t h o f a g u s a t a l t i t u d e s a b o v e t h e l i m i to f w o o d l a n d : s t a nd s o f N. g l a cu a o n s u m m i t s o ft h e C o a s ta l M o u n t a i n s a t a b o u t 6 0 0 m a n d o f

N. o b l i q u a b e t w e e n 8 0 0 - 1 6 5 0 m o n t h e w e s t sl o p eo f t h e A n d e s ( D o n o s o , 1 9 75 ). A c c o r d i n g t oR o d r i g u e z e t a l . ( 1 9 8 3 ) , t h e n o r t h e r n l i m i t o fN. o b l i q u a i s a t a b o u t 3 3 S o n t h e u p p e r s l o p e s o fC e r r o L a C a m p a n a a n d C e r r o E1 R o b l e a ta l t i t u d e s b e t w e e n 1 5 0 0 2 2 0 0 m ; N. g l a u ca e x t e n d st o a b o u t 3 4 S ( 5 0 0 m ) a n d N. a l p i n a t o 35 S( 1 0 00 m ) ; a n d o t h e r s p e ci es o f d e c i d u o u s b e e c h ,N. a n t a r c t i ca a n d N. p u m i l i o , b e l o n g i n g t o t h e h i g ha n d e a n b e e c h f o r e s t , r a n g e t o 3 5 1 5 3 5 3 0 ' S( 1 6 0 0 - 1 8 0 0 m ) . E v e r g r e e n b e e c h ( N . d o m b e y i ) int h e A n d e s r e a c h e s th e n o r t h e r n e n d o f i ts r a n g ec l o s e t o 3 4 3 0 ' S ( 6 0 0 - 1 0 0 0 m ) .

T h r e e a r b o r e a l g y m n o s p e r m s , a l so r a n g i n ge q u a t o r w a r d f r o m a m o r e s o u t h e r l y d is t ri b u t io nl o c u s , o c c u r a t s c a t t e r e d s t a t i o n s a l o n g t h e s u b -t r o p i c a l a n d e a n f r o n t . G r o w i n g a s f a r n o r t h a s3 5 4 5 ' S a r e t w o p o d o c a r p s P r u m n o p i t y s a n d i n a

m .- ~ ,, No thofagus pumilio3 0 0 0 - ~ - N. an ta r c t i ca- ~ , N. dombey i

2000- ~ '~,1000- -. ~.,, e -1000

n -O - , : , : : : , : : i i ! : : , : : ~ , : : ' , : : : : ! : : i % . . . . - - - ' - ' % , , ~ - o32 33 34 I 35 36 37 38 39 40 41S. Lat.

iL. de Tagua Taguam .~ ~ o No tho fagus obl iqua3000- ~ ~ N. glauca

D N. alp ina2000- o ~ ~ r ~ m.

- . 0 . 0 0 o . . . . . ~ o o o o o

32 33 34 I 35 36 37 38 39 40 41S . Lat.iL. de TaguaTagua

m .

3 0 0 0 - ~ * Prumnopi tys andinaPod c ar pus satigna

, o o o - . . . . . 1000

32 33 34 ] 35 36 37 38 39 40 41 S. Lat.L . de TaguaTagua

F i g . 3 . D i s t r i b u t i o n o f s p e c i e s o f Nothofagus, Prumnopitys, a n d Podocarpuso n t h e w e s t s l o p e o f t he A n d e s M o u n t a i n s w i t h r e f e re n c e t op l a n t f o r m a t i o n s ( s e e F i g .2 ) a n d t h e l o c a t i o n o f L a g u n a d e T a g u a T a g u a . D a t a a r e f r o m v a r i o u s s o u r c e s i n cl u d i n g R e i c h e (1 9 07 ) ,D o n o s o ( 1 97 5, 1 97 8) , R o d r i g u e z e t a l. ( 19 8 3 ), a n d u n p u b l i s h e d r e c o r d s .


6/21

112 C.J. HEUSSER( 1 0 0 0 - 1 1 0 0 m ) a n d Podoc arpus sa l i gna ( 1 5 0 0 m ) .T h e t h i r d g y m n o s p e r m Austocedrus chi lens i s( C u p r e s s a c e a e ) i s e s t a b l i s h e d m o s t e q u a t o r w a r dn e a r 3 2 4 0 'S ( 1 7 0 0 - 2 0 0 0 m ) .Laguna de Ta gua TaguaLocat ion and physical se t t ing

T h e s it e o f L a g u n a d e T a g u a T a g u a ( 34 30 'S ,7 1 1 0 ' W ) i s a t e c t o n i c d e p r e s s i o n , l y i n g j u s tn o r t h w e s t o f S a n F e r n a n d o a n d 1 20 k m s o u t h w e s to f S a n t i a g o i n t h e P r o v i n c e o f O ' H i g g i n s ( F ig s . 1a n d 4 ) . I t i s s i t u a t e d a t a n a l t i t u d e o f 2 0 0 m i na g r i c u l t u r a l l a n d a t t h e e a s t e r n e d g e o f t h e C o a s t a lM o u n t a i n s . E x c e p t f o r a n a r r o w o p e n i n g t o w a r dt h e e a s t , t h e s i t e l i e s w i t h i n a c i r c u l a r r i d g e o f

v o l c a n i c a n d m a r i n e s e d i m e n t a r y r o c k s o f C r e t a c e -o u s a g e ( M a p a G e o l 6 g i c o d e C h i le , 1 9 82 ). T h es h a l l o w b a s i n o f t h e la k e w a s f o r m e d d u r i n g t h el a te T e r t i a r y - e a r l y Q u a t e r n a r y a n d e x t en s iv e lyf i l l e d b y l a h a r i c d e p o s i t s f r o m t h e A n d e s M o u n -t a i n s (V a r e l a , 1 97 6) . L a t e r a g g r a d a t i o n b y t h eE s t e r o Z a m o r a n o , a t r ib u t a r y o f th e R i o C a c h a -p o a l , a p p a r e n t l y c o n t r i b u t e d f u r t h e r t o w a r d i m -p o u n d m e n t o f t h e la k e.

L a g u n a d e T a g u a T a g u a b e f o r e b e in g d r a in e d i n1 8 41 m e a s u r e d s o m e 3 0 k m 2 in a r e a w i th am a x i m u m d e p t h o f 5 m ( V a r e l a, 1 9 76 ). I n t h e e a rl y1 9 t h c e n t u r y , t h e l a k e w a s w i d e l y r e n o w n e d f o r i tsu n u s u a l f l o a t in g i s la n d s , c o n s i s t in g o f i n t e r w o v e nr h i z o m e s a n d s t e m s o f c a t t a il a n d w a t e r w e e d s( R e i c h e , 1 9 0 7 ) . A s t h e w i n d b l e w , t h e y c a r r i e dc a t t l e a s p a s s e n g e r s f r o m s h o r e t o s h o r e ( G a y ,

Fig.4. Setting of L aguna de Tagua Tagua. Based on Instituto Geogr~ificoMilitar quadrangles, San Vicente de Taguatagua (1984) andChimbarong o (1984) drawn to a scale of 1:50,000, with altitudinal limits of the flo or of the lake from the Lagun a de Tagua Tagua(1930) quad rangle on a scale of 1:25,000.


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ICE AGE VEGETATION AND CLIMATE OF SUBTROPICAL CHILE 1 13

1833; Darwin, 1958). Drainage was effected byconstruction of a canal between the north shoreand Estero Zamorano (Fig.4). This was done inconjunction with digging a network of ditchesacross the lake floor, making the basin suitable forcultivation of crops.P r ev i o u s wo r k : m a cr o f o s s i l r em a i n s a n ds t r a t i g r a p h y

Remains of extinct Pleistocene mammals, especi-ally bones of mastodon, encountered duringexcavation work, pointed to the antiquity of thelake deposit (Wyman, 1855; Oliver, 1926). Mostnotable has been the recent discovery of mastodonbones in association with human artifacts andcharcoal dated at 11,380 yr B.P. (Casamiquela etal., 1967; Montan6, 1968, 1969; Pino and Varela,1977). Stratigraphic studies made of exposuresalong the drainage canal indicated a complex lateQuaternary history of lacustrine deposition, inter-rupted at times by low lake levels and erosion, overan estimated time span of 57,000 years (Varela,1976).

The basal unit described by Varela (1976) islaharic, consisting of a matrix of volcanic ashcontaining fragments of andesitic rock and pumicestones, with a thickness of > 6 m. Sand and gravel(member 1, up to 2 m thick), overlie the depositand underlie 10.58 m of lake sediments, beginningas greenish-gray clay, containing at levels molluscs(Trop icorb i s ) and other fossils (member 2,10.58 7.25 m). Successively higher in the sectionare beds of yellowish clayey mud and some sand,intercalated by mud and by sand and gravel, withfossil deer (A n t i f e r ) , each showing signs of erosion(member 3, 7.25-5.61 m; member 4, 5.61-4.49 m);greenish clay, also showing evidence of erosion,containing bones of birds, fish, and other verte-brates (member 5, 4.49-2.35m); dark clayeycarbonaceous mud with paleo-Indian chippedtools, scrapers and flakers, among abundantremains of extinct mastodon ( M a s t o d o n ) , horse(H i p p i d i o n ) , deer (H i p p o ca m e l u s ) , birds, frogs, fish,and rodents (member 6, 2.35-2.07 m), yellowishgray mud with diatoms, sponge spicules, ostra-cods, fish scales, and bones of frogs and birds,along with seeds and related plant material

(member 7, 2.07 1.04 m); and dark clayey, carbon-rich paleosol charged with vertebrates and objectsremaining from human occupation, projectilepoints, stone knives, and grinding stones (member8, 1.04-0 m). Dates reported from levels in theupper beds (Montan& 1968, 1969) are 11,380+320yr B.P. at 2.3m and 6130_+115 yr B.P. at 1.0m.

Laguna de Tagua Tagua, according to thestratigraphic observations made by Varela (1976),was at low level during intervals at the beginning ofthe lacustrine record, during the deposition ofmember 4, following deposition of members 3, 4,and 5, and late in the record of member 7. Episodesof relatively high water are contained in members 2and 5 and stands of moderately high water inmember 7 and the upper part of member 8.Reference is the level of the lake prior to drainage.P o l l en a n d m i c r o f o s s i l s t u d i e s

Two sections of the lacustrine sediments ofLaguna de Tagua Tagua for the study of fossilpollen and spores, one of 10.7 m and the other of3.2 m, are from the central part of the lake (Fig.4).The location is in the northeastern sector ofdrained lake bed, where a farm road, beginningabout 1200m distant on the upland, crosses amajor drainage ditch. The 10.7-m section extendsto the approximate time of drainage, which was thepreserved bottom of the lake resting beneathsediments dug up during construction of the ditch.Sampling of the 3.2-m section was done later forthe purpose of close-interval dating of upper levels.The location of the section is the margin of acultivated field in proximity to the deeper section,as the original site of coring was no longeraccessible. The upper 50cm of sediments, dis-turbed by cultivation, were discarded,Fourteen radiocarbon-dated levels show anaverage sedimentation rate of 51.4 yr cm 1.age-depth relations are indicated by the equationY=0.18192+ 1.9550e-4x (Fig.5), giving an esti-mated basal age of the 10.7-m section of 53,800 yrB.P. Sedimentation over the length of record wasnot uniform, as may otherwise be implied by astraight line fit of the dated levels. Owing to pastvariations in lake volume and water depth, inparticular, rates varied. To establish changes inrates of sedimentation, a larger data set is needed.


8/21

114 C.J. HEUSSERD e p t hm ,

O -

4

5 - 1

1 0

A v . s e d i m e n t a t i o n r a t e5 1 . 4 y r c m - 1

\ ~ " or - .\ %

0 1 0 2 ' 0 3 0 4 0 5 ' 0 5 ' 01 4 C y r B . P . X 1 0 3

Fig.5. Age-depth relations for the 10.7-m section from Laguna de Tagua Tagua. See Table 3 for data.Regional near-surface samples were collected for

study in conjunction with the fossil pollen studies.They are broadly representative of plant communi-ties existing over the latitudinal and altitudinalextent of subtropical Chile. Pollen in these samplesis intended to portray vegetation prior to Euro-pean settlement, when, for example, Pinus, Euca-l y p tu s , Ru me x , P la n ta g o , and H y p o c h o e r i s wereintroduced. Many (but not all) of the samplestations are lakes or ponds, and their pollenspectra thus complement the fossil spectra in thelacustrine setting of Laguna de Tagua Tagua.Although these data are from an extensive region,wherein lakes are not consistently present, it issignificant to note that lake and non-lake stationsin proximity frequently record comparab le propor-tions of leading pollen taxa.

Section samples at 10-cm intervals and near-surface samples were processed in the laboratoryfor their pollen and spore content (Heusser andStock, 1984). Identifications are from modernreference collections and published accounts(Heusser, 1971; Markgraf and D'Antoni , 1978;Villagr~in, 1980; Wingenroth and Heusser, 1984).Among species of No th o fa g u s , N . d o mb e y i type(including N . d o mb e y i , N . a n ta rc ti c a , N . p u mi l io ,

N. n i t ida) and N . o b l iqu a type (including N . o b l i-qu a , N . a lp &a , and N . g la u ca ) are alone deter-minable. Frequencies (%) of tree, shrub, and herbtaxa are from sums of at least 300 grains and ofaquatics and vascular cryptogams from sums of>300 total pollen and spores. Plant nomencla-ture follows Marticorena and Quezada (1985),except where plant names are given in citedreferences.Mo d e rn p o l l e n sp e c t ra

Near-surface sampling stations 1-58 are locatedbetween approximately 30-40S (Fig.6, Table 2).Stations in the north (1-13), mostly in broadsclerophyllous woodland, are distinctive. Theyshow high proportions of Gramineae (grasses),Chenopodiaceae-Amaranthaceae (chenopods-amaranths), and Tubulifiorae (composites) withvariable amounts of woodland indicators, forexample, Qu i l la ja , Ma y te n u s , S c h in u s , and L i th -raea (Fig.7). Stations on Cerro E1 Roble (3, 4), thenorthern outlier of deciduous beech, clearly revealthis lacuna by a maximum of 36% of N o t h o f a g u sob l iqua type; minor amounts of N . d o m b e y i typefound there and elsewhere in the north are wind


9/21

I CE A G E V E G E T A T I O N A N D C L I M A T E O F S U B T R O P I C A L C H I L E [ 15

- 3 0

- 3 2

g_ 3 4 o o e ~ 5 ',, ] 'o 7 . ; i

" - ' t ' 8 ~ g io L a g u n a d e / u , ,e 1 1 , ' /Tagua Tegua[~] , , j

/ " 4 ~i ' ~ '~ "-~_ 3 6 , ' , ', ~ ! ~ ", " / C ) .~)I / " ' ~ "Conc e pc i6n [ ] 1 ~ /: ~ e 2 / 1 4 c t 7

- i "t " ~ ' s - , o- 3 B ', . . . . . , , I - ~ ,/ ~ i3 4 - 3 g ; , 2 t - 2 6~ - , , t . 4 " + . 7 7 - 3 3

4 4 ;)e,s43 ,J4 5 e " !;7 " 4 ' 2 4 f - 4 7. 5 1 - 5 6V s l d l v l a- 4 0 - ~ ~ s % 4 9 ~

5 0 r )L ~ / ~ 7 1 2 ':

IL a S e r e n a ~ o " - _ :- - i ' ef l 1 ] i/ J

[ " I - - /i /m l r ,

, , , , s

2 ' ; ~ i3 , ~ 4 io S a n t i a g o

7 OB0 1 0 0 2 0 0 3 0 0 k m .i i i p

[ ] S ubt rop ic a l t horn - s hrub- succulent vegetat ion[ ] Subtropical broad sclerophyllousw oodla nd ( m a t or ra l )[ ] De c iduous be e c h f ore s t

[ ] Evergreen ra in forest

H igh a nde a n be e c h f ore s t ( = , 3 7 )& t undra ( und i f f e re nt ia t e d)

Fig.6. Subtropical and temperate, near-surfacesample stations in Chile shown by number (Table 2) with reference o plant formations(Schmithfisen, 1956) and modern pollen spectra (Fig.7).transported from beyond source regions of highandean beech and evergreen rain forest. Lowpercentages of other woody taxa, for example,D r i m y s , Myrtaceae, and A e x t o x i c o n , reflect minorentomophilous constituents o f the vegetation.

Stations in the south or at altitudes higher in themountains (14 58) are for the most part indeciduous beech forest and evergreen rain forest.They portray large percentages of N o t h o f a g u s :N . obl iqua type, as much as 60%, and N . d o m b e y itype, reaching 92%. Woody plants, exemplified byL a u r e l i a , L o m a t i a , Myrtaceae, and A e x t o x i c o n , arealso indicative of these forests and are, at times,well represented. Stations for the gymnospermsP o d o c a r p u s s a l i g n a (14-17, 51 56) and P r u m n o p i -t y s a n d i n a (14-20, 27-33) reach percentages,respectively, of 43% and 84%. Percentages ofanother gymnosperm, A r a u c a r i a a r a u c a n a , which

grows in communities allied with high andeanbeech forest (3730'-4023%), are, by comparison,comparative ly low (maximum 33%). This is appar-ently the result of poor pollen dispersal, owing tothe large-size pollen grains (77-96 I~m), which sinkclose to source trees. Irregular percentages shownby Gramineae appear to be associated with varyingdegrees of openness in the vegetation, often causedby natural disturbances (fire, crustal movement,lahars). At certain high altitude stations (forexample, 21 24), Gramineae are indicative of highandean beech forest-tundra transition.F o s s i l r e c o r d o f t h e 1 0 . 7 - m s e c t io n f r o m L a g u n ad e T a g u a T a g u a

Five pollen assemblage zones (TT-1 to TT-5),the upper two divided into subzones, are recog-


10/21

116 C.J. HEUSSER

TABLE IISurface pollen stations in relation to vegetation, temperature, and precipitation"Station Location Alt.(m)

Lat. Long.Plantformation

Av. summertemp.(c)

Av. annualprecip.(mm)1 La Serena 2955 7117 102 Panquehue 3248 7050 5403 Co. El Roble 3258 7103 18904 Co. E1 Roble 3258 7103 18005 Lag. Lonquen 3343 7050 2006 Lag. Aculeo 3350 7055 2007 Angos. Paine 3355 7043 3008 Rancagua 3415 7035 10609 Rancagua 3415 7035 80010 Tagua Tagua 3430 7110 20011 Teno 3452 7110 300

12 Lag. Avendafio 3645 7227 10013 Lag. Mellizas 3719 7225 15014 Termas Chillfin 3648 7145 100015 Termas Chillfin 3648 7145 96016 Termas Chillfin 3648 7145 88017 Termas Chillfin 3648 7145 82018 Cen. E1 Toro 3717 7127 85019 Cen. E1 Toro 3717 7127 85020 Cen. E1 Toro 3717 7127 85021 V. Lonquimay 3825 7126 186022 V. Lonquimay 3825 7126 185023 V. Lonquimay 3825 7126 185024 V. Lonquimay 3825 7126 180025 V. Lonquimay 3825 7126 168026 V. Lonquimay 3825 7126 160027 Conguillio 3840 7137 122028 Conguillio 3840 7137 122029 Conguillio 3840 7137 110030 Conguillio 3840 7137 107031 Conguillio 3840 7137 104032 Conguillio 3848 7137 82033 Conguillio 3848 7137 75034 V. Llaima 3845 7150 150035 V. Llaima 3845 7150 140036 V. Llaima 3845 7150 124037 V. Llaima 3845 7150 100038 V. Llaima 3845 7150 94039 V. Llaima 3845 7150 85040 E1 Reloj 3905 7216 20041 El Reloj 3905 7216 200

42 Huilipi lun 3910 7210 24043 Villarrica 3910 7205 25044 Villarrica 3913 7214 22045 Rucafiancu 3933 7217 26046 Termas Palguin 3926 7148 79047 Termas Palguin 3926 7148 76048 Panguipulli 3950 7225 18049 Pto. Nuevo 4010 7235 10050 Lag. Ranco 4014 7230 10051 San Martin 3940 7310 5052 San Martin 3940 7310 5053 San Martin 3940 7310 5054 San Martin 3940 7310 5055 San Martin 3940 7310 50

1 17,1 602 19,0 2002-3 16,2 10002-3 16,5 10002 20,4 3002 20.0 4002 20,0 4002 19.5 6002 19.4 6002 20.0 8002 20.0 8002 19.0 12002 18.0 12003-4 12.5 20003-4 12.8 20003 -4 13.2 20003 -4 13.5 20003 -4 13.2 17003-4 13.2 17003-4 13.2 17005-6 9.7 20005-6 9.7 20005-6 9.7 20005-6 9.9 17005 10.3 17005 10.6 17004-5 11.9 30004-5 11.9 30004 12.3 22004 12.4 22004 12.5 22003-4 13.2 22003 -4 13.5 22005 10.9 40005 11.2 40004-5 11.8 35004 12.6 35004 12.8 30004 13.1 30003 16.3 20003 16.3 20003 16.2 23004 16.2 23003 16.2 23003-4 16.2 23004 16.0 42004 16.0 42004 16.0 25003 16.0 13003 16.0 13003 16.0 20003 16.0 20003 16.0 20003 16.0 20003 16.0 2000


11/21

ICE AGE VEGETATION AND CLIMATE OF SUBTROPICAL CHILE

T A B L E I I (continued)11 7

S t a t i o n L o c a t i o n A l t . P l a n t A v . s u m m e r A v . a n n u a l( m ) f o r m a t i o n t e m p . p r e c ip .

L a t . L o n g . ( " C ) ( r a m )56 San M ar t i n 3940 7310 50 3 16 .0 200057 Pail laco 4000 7308 150 3 16.0 250058 Pail laco 4005 7307 100 3 16.0 2500~ S t a t io n l o c a t i o n s b y s o u t h l a t i t u d e a n d w e s t l o n g i t u d e i n d e g r e e s a n d m i n u t e s , e a c h a s f o u r c o n s e c u t i v e n u m b e r s ( s e ed i s p l ay o f s t a t i o n s in F i g . 6 ); p l a n t f o r m a t i o n s b y n u m b e r a s f o l lo w s : 1 = s u b t r o p i c a l t h o r n s h r u b s u c c u l en t ,2 = s u b t r o p i c a l b r o a d - s c l e r o p h y l l o u s w o o d l a n d ( m a t o r r a l ) , 3 = d e c i d u o u s b e e c h f o r e s t, 4 = e v e r g r e e n r a i n f o r e st ,5 = h i g h a n d e a n b e e c h f o r e s t , a n d 6 = a n d e a n t u n d r a . S o u r c e o f c l i m a t i c d a t a i s A l m e y d a a n d S ~ e z (1 95 8) ; v e g e t a t i o nf o r m a t i o n s a r e a c c o r d i n g t o S c h m i t h i i s e n ( 19 56 , 1 96 0) w i t h m o d i f i c a t i o n .

/ T r e e s / ~ S h r u b s & h e r b s 7

, / , o o ,-' _oo . o , , , ' o ' M ' /-,~ " o~ o ~ . * ~ , ' ~ ,,,%" ~o,';*" .,o ~/ ,' " ,~ /oo'~ ~ e ,0 ;, " ~ o - - _ ,Q ~ o O % ~ t ' : # o , ' / , . ~ ' o ,~ - /~o , , ,~. e " , . .' . . , ." t ' ,d% ~"> o , +"= ' . t- . , . , ,. , ' - q ' ~ " L " & ~ ,* e " d " 4 ~ ' , ~ . ~ o ~ , ~

/ / / / / / .,, / / / / / / / / / / / / / / / / / / /~ ~ o;: ,_ ==== " , . . . . ,, ~

, l O - - L a g u n a d e T a g u a T a g u a - i . . . . ~ . . .. . .. . ' ~ ' ~ = = ~ " - I 0

2 0 - , == == , . . . . . . . ~ ~ ' - , ' -. ' , , , , , _ - 2 0o ~ : ' , , =~, ~= o=_, : ,==' ; ,~ o - ', ~ = . . . . . . '= . . . . . j ~ ' . ~ . . . . . . . . . . . . . . . := . . . . . . i - ~o= = = , = = ~ l

o , , ~ ,, ,., ~ ~ ~

4 0 . . . . . ! . . . . , . . . . : , ~ . . . . . . . - ' ; ~ , ' , ~ , * ; - 4 0~ , l = = = ' = = = = = i ' ' ' = ; , :

; , == , , ~ , ' ,, : ; = , , : ~ ,s o - : . . . . . . . . . . . . . . . . . . ' : = ~ . . . . ' . .. .. .. .. . ~ . . . . . . . . . . . L ' : . .. . ~ . . . . . . . . . . . . . . . . ' - s o= ; , ; ~ ~ = ~ ' , , ~ = =

= ; J ' . ~ ' ' ' r ' - : ' ' = . :[ - - I i I I I I ~ r - I - i - [ ' ' ' I ' ~ [ - -I r ~ i - r - i i [ - - r - i r , i ~ = i - l - - r - I - - r - l - -

O 0 0 0 0 0 0 0 0 O 0 0 O 0 0 O 0 0 0 0 0 00 1 0 0 %

F i g . 7 . M o d e r n p o l l e n s p e c t r a f o r n e a r - s u r f a c e s a m p l e s t a t i o n s i n s u b t r o p i c a l a n d a d j a c e n t t e m p e r a t e C h i l e ( T a b l e 2, F i g . 6 ).

nized in the pollen stratigraphy (Fig.8). Leadingtaxa throughout are Gramineae, chenopods-amaranths, and Tubuliflorae (Compositae); theprincipal arboreal components, N o t h o f a g u s d o m -b e y i type and P r u m n o p i t y s a n d in a , gain importanceat depth (zones TT-5 to TT-2). Table 3 covers thelithology of the section; Table 4 summarizes thepollen assemblages and radiocarbon time controlat and between zonal boundaries.

Z o n e T T - 5 , e s t im a t e d 5 3 , 80 0 - 5 0 , 0 0 0 y r B . P .Over a span of nearly four millennia, cheno-

pods-amaranths increase from 10% to a maximum66%, following an abundance of N . d o m b e y i typewith Gramineae and Tubuliflorae. This increaseparallels an apparent drying trend and lowering oflake level, whereby the peripherally exposed lakebed became invaded by a representative halophyticelement ( A tr ip l ex , S a l i c o r n i a , S u a e d a ) . Cheno-


12/21

118 C , J . H E U S S E R- . - : ~ : : : . . . . : ' ; ; ,

~ , ~ ! i ! ! , i i ~ , : , W l , , , , L , - - , , ' 1 1 ~ - i '~ , , i1 ~ I , , i , I i i i i l

. , . . I h . , , , , . : . . . . . . . . . . . . L , . . . . . . . . . . . . . . . . . . . , n . l l h J o -

" , , o ~ , g ; , ; ~ ' ~ ; o : ~ L . .. .. .. . 0 . .. . i . . E , i ; . . . . i . L" 9 / ~ ' ~ O r / o O C V i i i i i ! i i - ! : L

o ~ : : ~ F - ! - 0 ~ i - : ~ . . . . . . i i ~ [' % , . % ~ i i i . . ! o . . o . ~. . . . . . . . . . . . . . . . . . ..o . . . . . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . & ra e ~ e o ~ e : ' , : ' , : , , ~ : : [

~ % % : : i ! ! ! i i i . . . . i . L% o ~ % i i i i i : i : ! . i ~~ , ' ? ~ , . : t i l ' , , . : . . . . . . . . 1 , 0 1 i , , . i . , . . . h l h l l l | l l l | l i h l l l l l f - i . h h , . h . . . . l l h h . h , l l l d l lu i i m l l . . , . , , h , l ~ I - -

~ e o ~ . _ L L _ . ,. L . . . . . . . : . . L . . . . . . I .@ e l @

- ' ~ ' ~ , i i ! ! ! - [ . . . . . . . . [ : . . . . . . . . [ . . . . I , -~ :-~ - -- ~-- ?- ! - -': . . . . i% [ i i - i i " i . . . . . . . . !~ - ~ . e i : . " i ! i ' : " ! . . . . !

/ e . r L : : : : : . . . . . ' . .9 e ~ , : : :I e e , ~ , . . . . . . .e , , : , , , :% ~ ,,2 ~ . . . . . . . . . .: ~ ,~ L , i ll , . . . . . . . . h , . : . . . i . . . ! . . . . . . . . . . . . . . . . . ! . . . . . . . . i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L - ~~ , . , o % . , % ~ ! i i i i i _ i . i . i _

0 . . . . . . . . . . L _

e ~ e o d ? , " . . . . . , " " r , " ' , " - ; . . . . . . ; . . . . . . . : . . . . . . .e ~ e e e e ? L i : i ~ ' ~ . . . . l - : : L .

~'%'~o~o -! - ! i i - ; . . . . . . . . . . . . . . . . . . . . . . " . . . . . . . . ! . . . . . . . . . . . . . . . . . . . . . . .

)> " ~ o % 0


13/21

ICE AGE VEGETATION AND CLIMATE OF SUBTROPICAL CHILE

T A B L E 1 1 ILithology of sediments in 10.7-m section from Laguna deTagua TaguaDepth (m) Description

0 1.71.8 2.22.3 3.33.4 6.56.6 7.37.4 10.7

Da rk () l ive gray (5 Y 3/2)" s i l ty c layOlive yellow (5 Y 6/6) s i l ty c layD a r k b r o w n ( 1 0 Y R 3 / 3 ) c l a y , v a r i o u s l y i n d u r a t e dD ark o l ive g reen (5 Y 3 /2 ) c lay gy t t j aD a r k g r a y i s h b r o w n ( 1 0 Y R 4 / 2 ) t o d a r k b r o w n( 1 0 Y R 3 / 3 ) p e a t y g y t t j aG r a y ( 1 0 Y R 5 / 1 ) t o v e r y d a r k g r a y i s h b r o w n( 10 Y R 3 /2 ) s il ty c lay , bo t tom ing in sandy s i l ty c lay

" M u n s e l l S o i l C o l o r C h a r t s ( 1 9 7 5 ) .

pods-amaranths are identified in the modernpollen rain of the northern part o f subtropical Chile(Fig.7), where A t r i p l e x (for example, A. chi lense ,A . r e pandum , and A . phi l ippi i) are common on salinesoils (Navas, 1976). The significant percentages ofN . d o m b e y i type (maximum 29%) imply at least inthe beginning the immediate presence of beech,probably as thinly stocked woodland, which laterbecame decimated as drying advanced.

Z o n e T T - 4, e s t i m a t e d 5 0 , 0 0 0 - 3 5 , 5 0 0 y r B . P .During this extended interval, N . d o m b e y i type iscoupled with P r u m n o p i t y s a n d i n a and the Grami-

neae. Comparatively mesic conditions and higherlake levels seem apparent, albeit with somefluctuation, as indicated by the variable percent-ages of chenopods amaranths. Beech woodlandenriched by podocarp in the local vegetation isevident from the data, representing displacementof these trees northward and to a lower altitudecompared with today. Amounts of Gramineae andTubuliflorae running frequently >30% and asmuch as 44%, respectively, also imply muchopenness. Coincident are A c a e n a and R u m e x (alsoin zone TT-5). Species of these genera evidentlymigrated to the lowland from the andean cordilleraand higher latitudes, where, for example, A . m a g e l -lanica and R. cr isp iss imus , exist at present (Hau-mann, 1918; Moore, 1983).

Z o n e T T - 3 , e s t i m a t e d 3 5 , 5 0 0 - 2 8 , 5 0 0 y r B . P .Chenopods-amaranths at peak values (maxi-

mum 81% at 33,300 yr B.P.) dominate the record

I1 9

for some seven millennia. A drop in lake level isimplied, which sustained species of this group onthe exposed lake bed. Percentages of arboreal taxa,beech and podocarp in particular, are ratherirregular and not so striking as in zone TT-4.Climate, returning to a setting developed over thecourse of early millennia (zone TT-5), seems tohave been relatively dry and less favorable to treepopulations.

Z o n e T T - 2 , 2 8 , 5 0 0 - 1 0 , 0 0 0 y r B . P .For the entire record, quantities of N . d o m b e y i

type and P r u m n o p i t y s a n d i n a are highest, 32% and33%, respectively, before 14,500 yr B.P. in subzoneTT-2b. These quantities, in concert with increasedamounts of Gramineae, Tubuliflorae, and A c a e n a ,contrast minimal amounts of chenopods-amar-anths. Conditions supporting optimal beech po-docarp woodland expansion were thus in effect for14 millennia. Climate was evidently cooler withincreased precipita tion/humidity and reduced eva-poration to an extent not shown previously.Modern pollen stations in the Andes (Figs.6 and 7,Table 2) with comparable amounts of beech andpodocarp infer much greater precipitalion than atpresent. The lake, under a regime of high input,presumably greater than the interval of zone TT-4,must have attained its greatest size. After 14,500 yrB.P. in subzone TT-2a, as chenopods amaranthsand Gramineae increased under the warming/dry-ing trend o f the late-glacial, percentages of N . d o m -b e y i type and P r u m n o p i t y s a n d in a overall declined.

Z o n e T T - 1 , 1 0 ,0 0 0 0 y r B . P .Holocene sediments contain maximal cheno-

pods-amaranths (>50%) in subzones TT-Ie (be-fore 9000 yr B.P.), TT-Ic (between approximately6000-2500 yr B.P.), and TT-Ia (after about 200 yrB.P.). Subzones TT- ld and TT- lb (9000 6000 and2500 200 yr B.P., respectively), identify alternat-ing, corresponding peaks of Gramineae (> 25%),Gunnera chi lens is , Umbelliferae, and Pter is chi len-sis. Over the course of zone TT-1, arboreal taxabecome minimal; only subzone TT-Ib exhibits,along with E p h e d r a a n d in a , an increase of N . d o m -b e y i type. Poor depiction or absence of broadsclerophyllous woodland taxa in the latest record(for example, C ry p toc ary a , Qu i l l a j a , L i th rae a ) is


14/21

120 C.J . HEUSSERT A B L E I VP ol l en as sem blage and age s t r a t i g r aph ic d a t a fo r L aguna de T agua T agua aP o l l en P o l l en a s sem blage A geassemblage zone (14C yr B .P .)T T - I a . C h e n o p o d i a c e a e - A m a r a n t h a c e a e -(0 -0 . 2 m ) T ubu l i f l o r ae

. . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 2 00Gramineae-Nothofagus-Ephedra-Gunnera-Umbelliferae. . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 2 60 0C ben opod iaceae -A m ara n thacea e 2830 + 120(1.0 m, RL-1961). . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 6 00 0Gramineae-Gunnera- 6130 + 250Um bel l i ferae (1 .6 m, RL-1962)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 9 00 0C hen opod iaceae -A m aran thaceae 9100 + 360(2.0 m, RL-1952)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 1 0,0 00Gramineae-Prumnopitys- 9860__+ 320Nothofagus- (2.2 m, RL-1953)C hen opod iaceae -A m aran thaceae 11 ,170 + 320(2.3 m, RL-1954)! 2,970 + 390(2.4 m, RL-1955). . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 1 4,5 00Prumnopitys-Nothofagus- 14,500_+ 350G ram ineae -T u bu l i f l o r ae (2. 9 m , Q L - 1666)21 ,50 0 ___65 0(4.0 m, QL-1667)28 , 100+ 1400(5.0 m, QL-1668). . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 2 8,5 00C h e n o p o d i a c e a e - A m a r a n t h a c e a e - 2 9,8 0 0 + 1 00 0G ram ineae -T ubu l i f t o r ae - (6. 0 m , Q L - 1669)Nothofagus 33,300 _ 1400(6.8 m, QL-1670). . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 3 5,5 00Nothofagus-Prumnopitys- 37,000 + 2000G ram ineae -T ub u l i f l o r ae - (8. 0 m , Q L - 1671)C h e n o p o d i a c e a e - A m a r a n t h a c e a e > 4 3,0 0 0(9.0 m, QL-1672). . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 5 0,0 00

C h e n o p o d i a c e a e - A m a r a n t h a c e a e - > 4 5,0 0 0Nothofagus-Gramineae- (10.7 m, QL-1674)Tubul i f torae. . . . . . . . . . . . . . . . . . . . . . . . . . . . c a 5 3,8 00

T T - l b(0.2-0.6 m)T T - l c(0.6-1.5 m)T T - l d(1.5-1.9 m)T T - l e(1.9-2.3 m)T T - 2 a(2.3-2.9 m)

T T - 2 b(2.9-5.3 m)

T T -3(5.3-7.5 m)

T T -4(7 . 5 -10 m )

T I ' -5(10-10 . 7 m )

aD ep ths o f r ad ioca rbon-da t ed l eve l s i n zones l a - e and 2a a r e f rom the shor t s ec t i on(F ig . 9 ) and have been ad jus t ed by m eans o f t he po l l en s t r a t ig r aphy .

a t t r i b u t a b l e t o l i m i t e d p o l l e n p r o d u c t i o n d u e t oi n se c t p o l l i n a t e d a d a p t a t i o n s . W h e r e a s t h e a q u a t -i c / s e m i a q u a t i c C y p e r a c e a e a n d M y r i o p h y l l u m a r eb e t t e r r e p r e s e n t e d i n z o n e s T T - 5 t o T T - 2 , T y p h a

angus t i f o l i a , f o l l o w i n g p e a k Utricular ia i n s u b z o n eT T - l e , o c c u r s a l m o s t e x c l u s i v e l y i n z o n e T T - 1 ,c o n t r i b u t e d , a s l a k e le v e l s f e ll , b y p l a n t s c o n s t i t u t -i n g m a r s h y g r o u n d . D r y , s u b t r o p i c a l c l im a t e


15/21

ICE AGE VEGETATION AND CLIMATE OF SUBTROPICAL CHILE 121

prevailing over the past 10,000 yr of zone TT-Ibecame pronounced during subzones TT-le andTT-lc, when amounts of chenopods-amaranthsincreased, while shorelines of the lake are pre-sumed to have been lower.

Loss on igni t ionMaximum amounts o f ignition loss in zone TT-3

at depth (33-38%) result from optimal net organicaccumulation from lake biota roughly 35,000 yrago. Earlier in zone TT-4, lower values imply lessthan optimal conditions for accumulation. In zoneTT-5, quantities were low during the early stage oflacustrine deposition and, as climate becamesubtropical, were lowest in subzone 2a and zone 1.

CharcoalAmounts of charcoal (gm 2 cm 2 X 103) increase

in zones TT-5 and TT-3. But it is not until later inupper subzone 2a, near the close of the late-glacial,and subsequently in zone 1 that charcoal becameabundant . Values appear to increase in phase withGramineae (out of phase with chenopods-amar-anths), suggesting a relationship with rising lakelevels, which may favor charcoal preservation.Some oxidative loss of charcoal was possible,however, at times when the lake was seasonallydry.

Charcoal in upper zone 2a is presumed to resultfrom burning by paleo-Indians, who are firstknown to have been active about the lake 11,380 yrago (Montan6, 1968). Large concentrations ofcharcoal in the late-glacial and Holocene alternatewith maxima of chenopods-amaranths. Theseamounts suggest that human use of fire as a meansto hunt game occurred at corresponding times ofhigh lake level, when climate more favorable tohabitation attracted hunters.Fossi l record o f the 3.2-m sec t ion

The section, from below 50 cm of cultivated soiland thus truncated at the top, embraces subzonesTT-2b TT- lc (Fig.9). Its pollen assemblages andzonation correspond in the main with the upperportion represented by the 10.7~m section (Fig.8);variable kinds and amounts of pollen produced/preserved locally account for differences in the

records. Trends set by the principals (Prumnopi t y s ,N ot ho f agus , Gramineae, chenopods-amaranths,and Tubuliflorae) show only slight variation.

Radiocarbon dates provide the basis for chrono-logical control used in the late-glacial and Holo-cene zonation of the 10.7-m section (Table 4). Thedates, unfortunate ly with large errors, are con-sidered reliable, except perhaps the uppermost of2830_+120 yr B.P. at 1.0m and 6130+_250 yr B.P.at 1.8 m in the section, as these sample levelspossibly contain modern roots. For comparison isa date of 6130_+115 yr B.P. obtained fromsediments 1.0 m below the top of the lacustrinesequence at the site of the drainage canal (Mon-tan6, 1969). Deeper in the 3.2-m section, the date of11,170+ 320 yr B.P. at 2.5 m, agrees closely with adate of 11,380+_320 yr B.P. from 2.4 m at the canal(Montan~, 1968).Est im at ion o f lake leve l f luc tuat ions f ro mm icro oss i ls

Frequencies of aquatic seed plant pollen (con-sisting principally of Typha a ngust i fol ia and Cyper-aceae; Fig. 8), algal remains (Pedias t rum andBotryococcus) , dinoflagellate cysts (cf Peridinium),and massulae of water fern (Azollaf i l iculoides) areshown in relation to pollen o f principal tree, shrub,and herb taxa (Fig.10). For reconstructing pastlake levels, algae and dinoflagellates have poorindicator value, owing to the diversified condit ionsunder which they are found (Hutchinson, 1967). Ofthe remaining microfossils, Typha angust i fol ia andAzolla f i l iculoides are characteristic of developingshallow water. In conjunction with the cheno-pods-amaranths, inhabitants of mud flats duringtimes of low water, these groups serve to estimatelake level. While the chenopods-amaranths rangewidely in Chile, T y pha is temperate-subtropical;Azol la grows throughout below an altitude of2000 m (Looser, 1961).

Diminution in size of Laguna de Tagua Tagua,following origin of the lake, is inferred by increasein chenopods-amaranths. This is corroborated bythe shoaling conditions, under which quantities ofAzol la were deposited in upper zone TT-5 (Fig. 10).Later, after an interval of relatively high water,lake levels appear to have been lower when


16/21

1 2 2 c . J . H E U SS E R

/ T r e e s ~ / S h r u b s & H e r b s ~ / A q u a t i c s & C r y p t o g a r n > 7

. , - , ,,o .,o. ~ . o ~ . . ~ o ~ . i # . . ~ - . . . .% o ~ # ~ . o ~ ~ . . o - ~ o ~

: . . . . . . . . . . " . . . . . . i . . . " . . . . . . . . . = = - - - E . . . . . . . . . . . .. . ~ . . . . . . : . . . . . . . . . . . . . . . . . . . . . . . . .2 8 3 0 _+ 1 2 0 - -> 1 - . ' - =~=== ,~, ~ : T T - l c,_ ._ ~== g ===. . . . . . . . , . . . . ,, . . . . . . . . . . . . , , . . ~ = . . . . . ~ . . . . . . . . . . . . . . . _ - - - - : - ! - . , . - : . . . . . . . . . ~ _ _ = . . . . . . . . . . .. . . : - - . . . . : . . . . . . . . . . . . . . . . . . . . . . . . .- - i i6 1 3 0 + 2 5 0 - - > : : , 11 . . . . ~ lib ~ ~ . . . . T T - - ld: ~ , : , - - - : : = - : , . = :

2 - : . . . . . . . . : - : - - i . . . . . : . . . . . : - - : - - , - - - . = - - - - - : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~ = - - - = . . . . . . . i . . . . . ! - = = =- . . . . . : . . . . . . . . . . . . . . . . . . . . . . . .9 1 0 0 _+ 3 6 0 ~_ > , " _ . . . . . : . . . . . . ~ == := = . ' = ; T T- l e9 8 6 0 + 3 2 0 ~ . ~ _ . . . . . " . . - . ' . ._ ;, _ . . . . . . . . , _ . ~ . . . . . . ~ . . . . . . . . . . . ~ __ ,_ ; : ,, ~ i : ,, ~ : , ; . . . . . . . . . . . . . . . . . . . . . . .1 1 ,1 7 0 ~ 3 2 0 -- ~ - -~ : : ~ ; ' ', ~ I , : - - ' . . . . : - - " " - -m . . . . . . . . " . . . . ' . . . . . . . . = . . . . . . ' . . . . . . . . . .1 2 ,9 7 0 _+ 3 9 0 / - ~ i : ' = i ' ; i I : ' i ' . ' : : ~ ', '= ~ ; . " ' T T -2 a- ~ - - - ~ . . . . . = - - : . . . . . . . . . i ~ . . . . . . ~ . . . . . . . . . . . . . ' . . . . . ' . . . . . . : - 3 ! - - . . . . . . . . ' - - : . . . . . ~ . . . . . t . . . . . . : . . . . . . . . . . . . . . . . . . . ~ - Q ~ - . . . .

I ' ' I - F ~ ~ - F F ~ - r F ~ I ' ' ' C C C C C F C C I ' ' [ - ~ -~ ~ [ ~ - [ - I ' r [ -7 5 %0

L a g u n a d e T a g u a T a g u a

F ig .9 . D iag ram o f po l l en and spore f r equency (t ree s, sh rubs and he rbs , and aqua t i c s and c ryp togam s) and r ad ioca rbon ch rono logy ,subd iv ided by po l l en a s sem blage zones , fo r t he 3 . 2-m sec t i on f rom L agu na de T agua T agua . D i s tu rbed upp e r 0 . 5 m o f t he s ec t ion no tshow n./ Trees.hru.& her,s / .0uo,ics /

/ ~ o~ ~ / ~ ~ ~ ~~o o. -,~ ~ ,,~ ~ ~, ~ ~ ~ ~oO ~ o , . e n . . e . e . ,~ @ ~ ~ " ~ @ ~ : " ~ ~ ~ o x O o ~. " ~ o A s s e m b l a g e1 4 C y r B . P . / R *" / ~ o / 0 " / ~ ' ~ / j o / 0 ~ e / 0 / ~ / Z o n e s L o w H i g hx l O 3 r n .

o - : ; _- .; .: _: .: _: _: _ _ T _ :_ : .: _ :. :. 2 : . : _ : 5 _ ~ _ i ! 5 5 ! ! ~ i . . . . . . . . . . . . . . . . . ~ _ . ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .( 2 . 8 ) ~ 1 - ', I

( 9 . 8 1 ~ " 2 1~ ~ ! ~ 2 -. . . . . . . . . . . . . . . . . . . . . . .. . . . . . , . . . . . . . . . . . .1 , . 6 . . . . ~ - . . . . . . . . . . . . . . . . . ~ - . . . . . _ Z IZ 3 1

2 1 . 5 =" ~ ~,5 - " , ~ ~ ' - -,c~ . . . . . I ~ . . . . . . . ~ . . . . . . ~ . . . . . . . . . . . .6- i ~ ' ~ '9 . 8 ~ "

3 3 . 3 ~" 7 - ~ ~ -. . . . . . . . . . . . . . . . . . . . . ~ . . . . . . ~ . . . . . . . . . . .3 , . o ~ 3 - : ~ -

> 4 3 ~ 9 - ) " "1 o . . . . . . . . . . . . . . . . . ~ - . . . . . . I ~ ' ~ . . . . . . . . . . . . . ~ . . . . . . . . . . . .

> 4 5 > ~ ~ -- ~I I I J I I [ J I I I I I I ~ I I I I I I J J I I I I I I I I I I I I I I I

0 1 0 0 %L a g u n a d e T a g u a T a g u a

F i g. 1 0. F r e q u e n c y d i a g r a m o f t h e p o l l e n o f l e a d i n g t r e e s, s h r u b s , a n d h e r b s , p o l l e n a n d m i c r o f o s si l s o f a q u a ti c s , a n d r a d i o c a r b o nchron o logy , subd iv ided by po l l en a s semb lage zones , i nc lud ing e s t ima ted chan ges in lake l eve l, fo r the 10 .7 -m sec t ion f rom La gun a deT a g u a T a g u a .


17/21


chenopods-amaranths increased and A z o l l a reap-peared in zone TT-3. For the entire record, asimplied by the minimal amounts of indicator taxa,maximum levels apparently were reached in zoneTT-2b, which includes the time of the last glacialmaximum. Close to 14,500 yr B.P., on evidenceprovided by greater amounts of Cyperaceae andAzol la , in addition to increasing quantities ofchenopods amaranths, lake levels, while fluctuat-ing, began to drop.

The sum of data indicates that Laguna de TaguaTagua for the entire period of record was atminimum size with a considerable part given overto peripheral marsh during subzone TT-lc. Fossilasemblages in the zone consist of peak amounts ofchenopods-amaranths and seed plants (mostlyTypha angust iJo l ia , an indicator of brackish/alkal-ine water), while lacustrine Pediastrum, Botryococ-c u s , dinoflagellates, and A z o l l a are poorly repre-sented. Ultimately, late in the record, former lakelevels were regained to some extent (aquaticmicrofossils in their variety return in the record),after which, just prior to drainage, the lake againappears to have been decreasing in size.

This interpretation of the history of Laguna deTagua Tagua closely follows the account given byVarela (1976). The microfossil data thus, in themain, complement the geomorphic and macrofos-sil evidence previously used to reconstruct thesequence of past events. Ages employed by Varela(1976), however, based on two radiocarbon datescovering the top 2 m of sediments (Montan6, 1968,1969), apply only to the Holocene and late-glacial,whereas at depth, the chronology has been esti-mated. In addition, the three intervals of erosionnoted at the canal exposure were not observed inthe core from the central part of the lake, althoughcorresponding times of comparatively low water,when erosion occurred on the exposed margins, arerecognizable.S u m m a ry p o ll e n d ia g ra m o f e x tra - lo c a l t a x a

Overrepresentation by chenopods amaranths(Fig.8), apparently having invaded the exposedbottom of Laguna de Tagua Tagua when waterlevels were low, mask performances of plants incommunities established beyond the periphery of

the basin. It is instructive, therefore, to examineextra-local taxa in profiles generated by omittingchenopods-amaranths. Principal taxa are southernbeech, podocarp, grass, and composite, whichrepresent > 90% of remaining pollen (Fig. 11).Southern beech is dominant in the Pleistocenethrough much of the lower part of the section.Beech declines upward after reaching a peak inzone TT-2 and follows trends not unlike those inthe diagram of total pollen (Fig.8). Trends ofpodocarp are likewise comparable in both dia-grams, revealing greater emphasis, when cheno-pods-amaranths are excluded, of an increase ofpodocarp in zone TT-3. Grass and composite,more or less of equal frequency at depth, are ofgreatest importance in zone TT-1 during theHolocene. Fluctuations, emphasizing the interplayof these nonarboreal types, show grass the domi-nant early in upper zone TT-2 and later in upperzone TT-I.

On the assumption that the chenopods-amar-anths reflect episodes o f relatively xeric conditionsin the record, it seems likely that more mesicbeech podocarp communit ies at these times wereless extensive and, therefore, le ss pollen pro-ductive. However, in the absence of pollen influx,which, given the limited time control, was notpossible to calculate reliably, frequency dataprovide no insight as to numbers of these taxa.D i s c u s s i o n

Climate and vegetation of subtropical Chile forthe last >40,000 yr of the Pleistocene, as inter-preted from Laguna de Tagua Tagua stratigraphicdata, are clearly contrasted with the setting ineffect over the past 10,000 yr of the Holocene.Changes in the ice age landscape were consider-able, broadly adhering to the directional patternrecognizable in contiguous parts of the andeancordillera of Chile-Argentina. Few data fromelsewhere in southern South America for the timespan covered by the lake record establish climaticparameters or explanatory mechanisms for theshifting environmental episodes.

Implications regarding temperature and precipi-tation during Pleistocene episodes of southernbeech-podocarp woodland (zones 4 and 2; Fig.8),


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124 C. J, HEUSSER

~ ~ / / T r e e s / ~ - S h r u b s & h e r b

D e p t h ~ A Q A s s e m b l a g em . e o ~ 9o ~ o o " Z o n e s 1 4 CO - / " ~ y r B . P .x l O 32 -4 -

1 0 . 0

2 8 . 56 -8 - 3 5 . 5

1 0 - 5 0 . 0r - i F ~ i% 0 2 '5 5 ' 0 0 2 '5 5 ' 0 0 2 '5 5 ' 0 7 5 0 2 '5 5 ' 0

F i g . l l . F r e q u e n c y p r o f i l es fo r t h e 1 0 .7 -m s e c t io n o f La g u n a d e Ta g u a Ta g u a o f m a j o r t r e e t a x a ( s o u t h e r n b e e c h a n d p o d o c a r p ) a n ds h r u b a n d h e r b t a x a ( g ra s s a n d c o m p o s i t e) a f t e r o m i t t in g c h e n o p o d s - a m a r a n t h s f r o m p o l l en s u m s .w h e n p r e c i p i t a t i o n / e v a p o r a t i o n r a t i o s w e r e a p p a r -en t ly h ighes t , a r e f rom es t im ates de r ived f rom thenear - su r face po l l en s t a t ions (T ab le 2 , F igs. 6 and7 ) . A v e r a g e s u m m e r t e m p e r a t u r e a n d a n n u a lp rec ip i t a t ion a t s t a t ions where pe rcen tages o fNothofagus a n d Prumnop i t y s a p p e a r c o m p a r a b l et o p e r c e n t a g e s r e a c h e d i n s u b z o n e T T - 2 b ( s ta t i o n s14-20 and 29-33 ; F ig . 7 ) a r e , r e spec t ive ly , c lose to13C and 2000 m m . These da ta , r ep resen t ing then e a r e s t m o d e r n a n a l o g s a n d a p p l i c a b l e t o t h e l a s tg l a c i a l m a x i m u m , i m p l y a t e m p e r a t u r e d e p r e s s i o no f a b o u t 7 C a n d a n i n c r e as e o f 1 2 0 0 m mprec ip i t a t ion (p resen t -day es t im ated va lues fo rL a g u n a d e T a g u a T a g u a a r e 2 0 C a n d 8 00 m m ;Tab le 2 ) . In s tances o f Nothofagus i n p e a k a m o u n t sa n d Prurnnopitys m i n i m a l o r u n r e c o r d e d ( c o m p a r em o d e r n h i g h m o n t a n e v e g e t a t i o n s t a t i o n s 3 7 a n d38 ; F ig . 7 , Tab le 2 ) ind ica te pos s ib le t em pera tu red e p r e s s i o n o f > 7 C a n d p r e c i p i ta t i o n g r e a t e r b y af a c t o r o f a r o u n d f o u r . T h u s , i t s e e m s r e a s o n a b l e t ob e l ie v e t h a t w h e n Prumnopi tys b e c a m e p r o m i n e n ti n u p p e r s u b z o n e T T - 2 b , c l i m a t e w a s n e i t h e r a sc o l d n o r a s w e t / s n o w y , a s i t w a s w h e n t h ep r o p o r t i o n o f Nothofagus ear l i e r was g rea te r .

E x p l a n a t i o n s t o a c c o u n t f o r f lu c t u a t in g l e ve ls o fm o is tu re in sub t rop ic a l Ch i le du r ing the i ce age a rec o n t a i n e d i n m o d e l s o f a t m o s p h e r i c c i r c u la t i o n f o rt h e S o u t h e r n H e m i s p h e r e ( s e e r e f er e n c e s in H e u s -se t , 1989a). The m ode l s f av or a cen t r a l m echan i sminvo lv ing osc i l l a t ions o f the po la r f ron t , inc lud ingvar iab le in tens i ty o f zona l c i r cu la t ion in the be l t o f

sou thern wes te r ly w inds . Op in ions d i f f e r , however ,r e g a r d in g d i r e c t i o n o f w i n d m o v e m e n t a n d s o u r c e so f m o i s tu r e . O n e p o s t u l a t e c o n t e n d s t h a t e x p a n -s ion o f the wes te r l i e s du r ing the fu l l -g lac ia l wasp o l e w a r d w i t h m o i s t u r e a t T a g u a T a g u a c o m i n gf rom a sub t rop ica l sou rce (Markgra f , 1989) . Theo t h e r m a i n t a in s t h a t t h e w e s t e rl y w i n d s y s t e m w a ss t r e n g t h e n e d e q u a t o r w a r d w i t h p r e c i p i t a t i o n c o m -i n g f ro m s t o r m s y s te m s a d v a n c i n g f a r t h e r n o r t h -ward than today (Heusse r , 1989b) .F o r s u b t r o p i c a l C h i l e , m o r e m e s i c c o n d i t i o n sdur ing the P le i s tocene a re ev iden t f rom re la teds tud ies , a lbe i t w i th no t im e con t ro l , o f thed i s t r ib u t i o n o f ex t i n ct a n d r e li c t b i o t a ( K u m m e r o wet a l ., 1961 ; Paskof f , 1970 ; Tro nco so e t a l ., 1980 ;Vil lagrf in and Ar m esto , 1980; P~rez an d V illagrfin ,1985) . W es te r ly c i r cu la t ion in the c i r cum pola rv o r t e x is t h o u g h t t o h a v e e x t e n d e d a n e s t i m a t e d 5 o f la t i tude in to the sub t rop ics (Cav iedes andP a s k o f f , 1 9 7 5 ; L a u e r a n d F r a n k e n b e r g , 1 98 4) ,s p r e a d i n g c o o l e r , w e t t e r c o n d i t i o n s n o r t h w a r df rom the sou th o f Ch i le . Sh i ft ing o f f ron ta l sys tem sw a s b o t h p o l e w a r d a n d e q u a t o r w a r d , i n k e e p i n gw i t h a c c o m p a n y i n g c h a n g e s i n t h e s u b t r o p i c a la n t i c y c l o n e , a s e x p l a i n e d b y L a u e r a n d F r a n k e n -berg (1984) . The an t i cyc lone l ay over in te r io rS o u t h A m e r i c a d u r i n g t h e l a s t g l a c i a l m a x i m u m ,hav ing sh i f t ed i t s pos i t ion eas tward f rom over thePac i f ic Ocean . Th us , m ore e f f ec t ive con t inen ta lh i g h p r es s u r e, b l o c k i n g t h e m o v e m e n t o f h u m i d a i rd i r e c t e d n o r t h w a r d a l o n g t h e C h i l e a n c o a s t , i s


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ICE AGE VEGETATION AND CLIMATE OF SUBTROPICAL CHILE ]2 5

in fe r r ed du r ing d r ie r m i l l enn ia o f the P le i s to -cene.

G l a c i e r a d v a n c e s r e c o r d e d i n t h e s u b t r o p i c a lArgen t ine Andes (Bengochea e t a l . , 1987 ; Esp iz t i a ,1989) , loca ted a t a som ewhat lower l a t i tude thanL a g u n a d e T a g u a T a g u a , p r o b a b l y o c c u r r e dd u r i n g t h e c o r r e s p o n d i n g , m o r e h u m i d i n t e r v a l sda ted 50 , 000-35 , 500 and 28 , 500-14 , 500 y r B . P . a tthe l aguna ( zones TT-4 and TT-2b : F ig . 10 ) . Thela tes t advance (Harcones ) , w i th t r aver t ine ages ondr if t of > 10,000 and at leas t 23,000 yr B.P . , fa l lsw i th in the l a s t in te rva l ; the advance p rev ious(Pen i t en tes ) , t en ta t ive ly b racke ted by t r aver t ineda tes be tween 38 , 000-23 , 000 y r B . P . , appear sre la ted to the one ea r l i e r .

Snowl ines , r i s ing f rom wes t to eas t du r ing t im esof g lac ie r advan ce , ind ica te g lac ia l nour i shm en t bym ois tu re f rom the Pac i f i c . Th i s m ois tu re source , a si t in f luenced l a te P le i s tocene h igh wate r a t Lagunad e T a g u a T a g u a , m a y a l s o a c c o u n t f o r h i g h l a k eleve l r eco rded eas t o f the Andes in Argen t ina .Sa l ina de l Be bede ro a t 3320 'S en la rged b e twee n17,500 13,200 yr B.P . (Gonzf i lez , 198 1; Gon zf i lezet a l. , 1 981; M . A. Gonzf i lez , pers . com m. , 1982),a n d L a g u n a C a r l L a u f q u e n n e a r 4 1 S w a s g r e a t e rin si ze be tween 19 , 500-15 , 000 y r B . P . (Ga l low ay e tal. , 1988),

N o r t h w a r d e x t e n s io n o f f r o n t a l s y s te m s re l a te dt o t h e b e l t o f s o u t h e r n w e s t e r ly w i n d s, a n h y p o t h e -s is to exp la in in te rva l s o f g rea te r p re c ip i t a t ion ino therwise d r i e r l a t i tudes du r ing the P le i s tocene , i sind ica ted by fos s i l ev idence f rom o ther geograph icsec to r s . Cush ion bog spec ies , adap ted to we t ,s o u t h e r n m o s t c o a s t a l C h i l e , b e c a m e e s t a b li s h e d o nI s la Grande de Ch i lo~ (42S) be tween27,00 0-18 ,000 yr B.P . (Vil lagrfin , 1988). Thism i g r a t i o n f o l l o w e d t h e m o v e m e n t n o r t h w a r d o ft h e z o n e o f m a x i m u m p r e c i p it a t io n , w h i c h a tp resen t i s pos i t ioned a t approx im ate ly 46S . Cush-i o n b o g s t o d a y a r e s c a t te r e d o n t h e t o p s o f t h eC o a s t a l M o u n t a i n s a s f a r n o r t h a s t h e C o r d i l l e r aP e l a d a a t 4 0 S . T h e b o g s f o r m d i s j u n c ti v e c o m m u -ni t ies , remaining in unique cl imat ic lacunae s incethe P le i s tocene , when coo le r , we t t e r cond i t ionsf a v o u r e d t h e i r s p r e a d n o r t h w a r d ( H e u s s e r , 1 9 8 2 ) .L a t e - g l a c i a l c l i m a t e a t L a g u n a d e T a g u a T a g u aa f t e r 1 4 , 5 0 0 y r B . P . , a s c h e n o p o d s - a m a r a n t h sbegan to m ul t ip ly ( subzone TT-2a ; F ig . 8 ) , was

c h a r a c t e r iz e d b y a n o v e r a ll i n c r e a se o f te m p e r a t u r ea n d i n t er v a ls o f d e s ic c a t io n . C o m m u n i t i e s c o n t a i n -ing Prumnopi tys , n o t o n l y a b o u t t h e l a g u n a b u talso at leas t as far south as 3930 'S (Heusser ,1984) , r em ained a t low a l t i tudes un t i l approx i -m ate ly the c lose o f the l a t e -g lac ia l . Prumnopitysover i t s r ange i s sub jec t to w in te r -wet , sum m er -d ryc l im ate , sugges t ing tha t i t s p rom inence dur ing thelate-glacial , as Nothofagus began to decl ine, fo l-l o w e d i n r e s p o n s e t o d e v e l o p i n g M e d i t e r r a n e a n -type c l im ate .

C l i m a t e d u r i n g t h e H o l o c e n e , a s a t p r e se n t , w a sapparen t ly sub jec t to in te rac t ion be tween Pac i f i ccyc lon ic and an t i cyc lon ic a tm ospher ic cen te r s . Theprem ise tha t the po la r f ron t l ay cons iderab ly sou tho f E a g u n a d e T a g u a T a g u a d u r i n g t h e e a r ly p a r t o ft h e H o l o c e n e i s s u p p o r t e d b y d a t a f r o m R u c a -f i ancu a t 3930 'S wh ich show re la t ive ly warm anddry cond i t ions a t 10 , 000-8000 y r B . P . (Heus se r ,1 98 4) . P r o m i n e n c e s o f c h e n o p o d s - a m a r a n t h s( subzones TT- le , TT- Ic , and TT- la ; F ig . 8 ) , r e f l ec tg rea te r a r id i ty and pos s ib ly h igher t em pera tu res ,r esu l t ing f rom con t ro l by the Pac i f i c an t i cyc lone .C o n v e r s e l y , p e a k s o f t h e G r a m i n e a e ( s u b z o n e s T T -l d a n d T T - l b ; F i g. 8) , i n d i c a te t i m e s o f s o m e w h a th igher hum id i ty and inc reased inc idence o f cy -c lon ic s to rm s o f the wes te r l i e s . The im pl ica t ionf r o m c h e n o p o d s - a m a r a n t h s i n n e a r - s u r f a c e p o l l e ns ta t ion d a ta ( s t a t ion 1 , fo r exam ple ; F ig . 7 , Tab le 2 )i s tha t annua l p rec ip i t a t ion dur ing the m ax im umo f t hi s a s s e m b l a g e ( su b z o n e T T - I c , a p p r o x i m a t e l y6000 2500 y r B . P . ) m ay have d ropped to l eve l sc lose to 100 m m . Th is m a y r ep resen t the cum ula -t ive ef fect of drying, begin ning in the la te-glacial ,w h i c h e m p h a s i z e s th e g r o w i n g d o m i n a t i o n o f th ePac i f ic an t i cyc lone r eg iona l ly .

T h e l a s t a p p r o x i m a t e l y 2 5 0 0 y r o f r e c o r d c o v e rthe fina l ep i sode o f peak Gram ineae , inc lud ingsm al l bu t s ign i f i can t am oun ts o f Nothofagus a n dEphedra, and the la t es t r is e o f che nop ods am a r -an ths ( subzo nes TT- I b and TT - la ; F ig .8 ) . C l im atei s e s t i m a t e d t o h a v e b e e n c o o l e r a n d m o r e h u m i d( s u m m e r t e m p e r a t u r e s p o s s i b l y 1 2 C b e l o w t h ep r e s e n t a n d p r e c i p i ta t i o n g r e a t e r b y > 4 0 0 m m ) .Th is appa ren t ly p re ceded a r ever sa l o f t r end , and ,over the pe r iod , l ed to inc reased sub t rop ica lcond i t ions .

I n c o n c l u s io n , t h e s e q u e n c e o f l at e Q u a t e r n a r y


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126 C.J. HEUSSERv e g e t a t i o n r e p l a c e m e n t s o b s e r v e d a t L a g u n a d eT a g u a T a g u a i s a s c r i b e d t o a p r e d o m i n a t i n g ,var iab le s to rm pa t t e rn , r egu la ted by the va ry ings t r eng th o f wes te r ly w ind c i r cu la t ion . T he pa t t e rn ,in e f f ec t , i s a m od i f i ca t ion o f ex i s t ing c l im atecon t ro l s , whereby changes in s easona l p rec ip i t a -t i o n , c a u s e d b y i n t e r a c t i o n b e t w e e n p o l a r a n dt rop ica l m ar i t im e a i r m as ses , invo lved a f luc tua t ingp o l a r f r o n t . V e g e t a t i o n r e p l a c e m e n t o f b r o a ds c l e r o p h y ll o u s w o o d l a n d o c c u r r e d a s a r e s p o n s e toP le i s tocene c l im ate , when h igher p rec ip i t a t ion /eva-pora t ion r a t io s , r e su l t ing f rom g rea te r s to rma c t i v i t y u n d e r c o n d i t i o n s o f r e d u c e d i n s o l a t i o n ,c h a r ac t e ri z e d i n t er v al s o f b e e c h - p o d o c a r p w o o d -land in sub t rop ica l Ch i le .Acknowledgments

T h a n k s a r e e x p r e s s e d t o t h e l a t e C a r l o s M u f i o zP . , wh o in 1963 f i rs t ca l l ed m y a t t en t ion to L agu nad e T a g u a T a g u a , a n d t o E u g e n i o S i e r r a R . , w h oas s i s t ed w i th the f i r s t s ec t ion t aken f rom the l akeb e d t h a t y e a r . T h a n k s a r e a l s o e x t e n d e d t o L . E .H e u s s e r , A . H a u s e r Y . , M . M u f i o z S . , a n d S .More i r a E . fo r as s i s t ance du r ing subsequen t f i e ldexcur s ions ; M. T . Caf ias P . , Se rv ic io Nac iona l deGeo log ia y Miner ia , fo r f i e ld t r anspor ta t ion ; M.S t u i v er a n d C . T u c e k f o r r a d i o c a r b o n d a t in g ; L . E .H e u s s e r a n d E . S t o c k f o r l a b o r a t o r y p r o c e s s i n g o fs am ples ; and B . van Gee l fo r c r it i ca l r ev iew o f them a n u s c r i p t . S u p p o r t e d b y N a t i o n a l S c ie n c e F o u n -d a t i o n g r a n t s A T M - 8 1 1 5 5 5 1 , A T M - 8 3 0 8 0 2 1 , a n dA T M - 8 6 1 7 1 5 4 t o N e w Y o r k U n i v e r s i t y .ReferencesAlm eyda , A . E. and S f i ez , S . F . , 1958 . Rec0P i l ac i6n de da tos

c l imh t i cos de Ch i l e y mapas s in6p t i cos r e spec t ivos . Min i s t .Agr ic . , San t i ago , 195 pp .Armes to , J . J . and Mar t inez , J . A. , 1978 . Re la t ions be tween

v e g e t a t i o n s t r u c t u r e a n d s l o p e a s p e c t i n t h e M e d i t e r r a n e a nreg ion o f Ch i l e . J . Eco l . , 66 : 881-889 .Bengochea , L. , Po r t e r , S . C. and Schwarcz , H. P . , 1987 .P l e i s t o c e n e g l a c i a t i o n a c r o s s t h e h i g h An d e s o f Ch i l e a n dAr g e n t i n a . I n : P r o g r . w i t h Ab s t r a c t s , I n t . U n i o n Qu a t . Re s . ,7 th In t . Congr . , Ot t awa , 1987 , 127 .Br i ig g e n , M . J . , 1 9 5 0 . F u n d a m e n t o s d e l a Ge o l o g i a d e C h i le .In s t . Geogr . Mi l . , San t i ago , 374 pp .Ca s a m i q u e l a , G . R . , M o n t a n 6 , M . J . , a n d S a n t a n a , A . R . , 1 96 7.Co n v i v e n c i a d e l h o m b r e c o n e l m a s t o d o n t e e n Ch i l e Ce n t r a l .N o t . M e n s . M u s . N a c . H i s t . N a t . , 1 3 2 : 1 - 6 .

Cav iedes , C. and Paskof f , R. , 1975 . Qu a te rn a ry g lac ia t ions inthe Andes o f no r th -cen t ra l Ch i l e . J . Glac io l . , 14 : 155-170 .C l a p p e r t o n , C . M . , 1 9 8 3 . Th e g l a c i a t i o n o f t h e An d e s . Qu a t .Sci . Rev., 2 : 83-155.Co b o s , D . R . a n d Bo n i n s e g n a , J . A . , 1 9 8 3 . F l u c t u a t i o n s o f

s o m e g l a c i e r s i n t h e u p p e r A t u e l R i v e r b a s i n , M e n d o z a ,Ar g e n t i n a . I n : Qu a t e r n a r y o f S o u t h Am e r i c a a n d An t a r c t i cP e n i n s u l a . Ba l k e m a , Ro t t e r d a m , 1 p p , 6 1 - 8 2 .

Cor te , A . E. and Esp iz f l a , L. E. , 1981. Inven ta r io de g lac ia re s del a c u e n c a d e l R i o M e n d o z a . I n s t . A r g e n t . N i v o l . G l a c i o l . ,M e n d o z a , 6 2 p p .

D a r wi n , C . , 1 95 8 . Vo y a g e o f t h e Be ag le . B a n t a m , N e w Y o r k ,439 pp .Do noso , Z . C. , 1975 . Di s t r ib uc i6n eco l6g ica de l a s e spec ies deN o t h o f a g u s e n l a z o n a m e s o m 6 r f i c a. U n i v , Ch i l e F a c. C i e n c .For . Bol . T6c., 33: 1-21.

D o n o s o , Z . C . , 1 9 7 8 . D e n d r o l o g i a . A r b o l e s y a r b u s t o s d e Ch i le .Un iv . Ch i l e Fac . Cienc . Fo r . M anu a l , 2 , 142 pp .

Esp iz f l a, L. E. , 1986 . F luc tu a t ions o f the Rio de l P lom og lac ie r s . Geogr . Ann . , 68 : 317-327 .

Espizfla , L. E., 1989. Gla ciacio nes Pleis toc~nicas en la Q ueb rad ade lo s Harcones y Rio de l a s Cuevas , Mendoza , Rep t ib l i caArgen t ina . Thes i s . Un iv . San Juan , San Juan , 266 pp .Ga l l o wa y , R . W . , M a r k g r a f , V . a n d Br a d b u r y , P . , 1 9 8 8 . D a t i n gs h o r e l in e s o f la k e s i n P a t a g o n i a , Ar g e n t i n a . J . S o u t h A m .Earth Sci . , 1 : 195-198.

Ga y , C. , 1833 . Tag ua Ta gua . A nn . Sc i . Na t . , 28 : 369 .Go nzfi lez , M. A., 1981. Evid encia s paleocl im/~t icas en la Sal inad e l Be b e d e r o ( S a n Lu i s ) . I n : Ac t a s 8 t h Co n g . Ge o l . Ar g e n t .San Lu i s , 3 , pp . 411-438 .

Gonzf i l ez , M. A. , Musacch io , E. A. , Garc ia , A. , Pascua l , R. andCor te , A. E. , 1981 . Las l ineas de cos ta Ho locen o de l a Sa l inad e l Be b e d e r o ( S a n Lu i s , Ar g e n t i n a ) . I m p l i c a n c i a s p a l e o a m b i -en ta l e s se sus mic ro f6s i l e s . In : Ac ta s 8 th Congr . Geo l .Argen t . San Lu i s , 3 , pp . 617-628 .

Ha u m a n n , L . , 1 9 1 8 . La v 6 g & a t i o n d e s h a u t e s c o rd i ll ~ r es d eMendoza . An . Soc . Cien t . Argen t . , 86 : 121-188 ; 225-348 .

He u s s e r , C . J . , 1 9 7 1 . P o l l e n a n d S p o r e s o f Ch i le . M o d e r n Ty p e so f t h e P t e r i d o p h y t a , G y m n o s p e r m a e , a n d A n g i o s p e r m a e ,Un iv . Ar izon a P res s , Tucson , A r iz . , 167 pp .

He u s s e r , C . J . , 1 9 8 2 . P a l y n o l o g y o f c u s h i o n b o g s o f t h eCo rd i l l e ra Pe lada , P rov ince o f Va ld iv ia , Ch i l e . Qua t . Res .,17 : 71 -92 .

He u s s e r , C . J . , 1 9 83 . Qu a t e r n a r y p o l l e n r e c o r d f r o m La g u n a d eTagua Tagua , Ch i l e . Sc ience , 219 : 1429-1432 .He u s s e r , C . J . , 1 9 8 4 . La t e - g l a c i a l - Ho l o c e n e c l i m a t e o f t h e l a k e

d i s t r i c t o f Ch i l e . Qua t . Res ., 22 : 77 -90 .He u s s e r , C . J . , 1 9 87 . Qu a t e r n a r y v e g e t a t i o n o f s o u t h e r n S o u t hAm e r i c a . I n : Qu a t e r n a r y o f S o u t h Am e r i c a a n d An t a r c t i cP e n i n s u l a . Ba l k e m a , Ro t t e r d a m , 5 , p p . 1 9 7 - 2 2 1 .Heusse r , C. J . , 1989a . Po la r pe r spec t ive o f l a t e Qua te rna ryc l i m a t e s i n t h e S o u t h e r n He m i s p h e r e . Q u a t . Re s ., 3 2 : 6 0 - 7 1 .Heusse r , C. J . , 1988b . Sou th e rn wes te r l i e s du r i ng the l a s t g l ac ia lm a x i m u m . Qu a t . Re s . , 3 1 : 4 2 3 - 4 2 5 .Heusse r , L. E. and S tock , C. E. , 1984 . P repa ra t ion t echn iquesf o r c o n c e n t r a t i n g p o l l e n f r o m m a r i n e s e d i m e n t s a n d o t h e rsed imen t s wi th low po l l en dens i ty . Pa lyno logy , 8 : 225-227 .Hu t c h i n s o n , G . E . , 1 9 6 7 . A Tr e a t i s e o n L i m n o l o g y . I I .I n t r o d u c t i o n t o La k e B i o l o g y a n d t h e L i m n o p l a n k t o n .W i l e y , N e w Y o r k , N . Y . , 1 1 1 5 p p .


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Kummerow, J., Matte, V. and Schlegel, F., 1961. Zum Problemder Nebelw/ilder an der zentralchilenischen Kfiste. Ber.Dtsch. Bot. Ges., 74: 135-145.

Lauer, W. and Frankenberg, P., 1984. Late glacial glaciationand the development of climate in southern South America.In: J. C. Vogel (Editor), Late Cainozoic Palaeoclimates of theSouthern Hemisphere. Balkema, Rotte rdam, pp. 104-114.

Lliboutry, L., I956. Nieves y Glaciares de Chile. Fundamento sde Glaciologia. Univ. Chile, Santiago, 471 pp.

Looser, G., 1961. Los pteriddfitos o helechos de Chile. Revi.Univ., 46: 213-262.

MacPhail, D. D., 1973. The geomorphology of the Rio Tendlahar, central Chile. Geogr. Rev., 58: 517-532.

Markgraf, V., 1989. Reply to C. J. Heusser's "Southe rnwesterlies during the last glacial maximum." Quat. Res., 31:426 432.

Markgraf, V. and D'A nton i, H. L., 1978. Pollen Flora ofArgentina. Univ. Arizona Press, Tucson, Ariz., 208 pp.

Marticorena, C. and Quezada, M., 1985. Cat~ilogo de la floravascular de Chile. Gayana, 42:1 157.Mapa Geol6gico de Chile, 1982. Hoja No. 3. Serv. Nac. Geol .

Miner., Inst. Geogr. Mil., Santiago.Miller, A., 1976. The climate of Chile. In: W. Schwerdtfeger

(Editor), World Survey of Climatology. 12. Climates ofCentral and South America. Elsevier, Amsterdam,pp. 113 145.

Montan& J. C., 1968. Paleo-lndian remains from Laguna deTagua Tagua, central Chile. Science, 161:1137-1138.

Montand, J. C., 1969. Fechado del nivel superior de TaguaTagua. Not. Mens. Mus. Nac. Hist. Nat., 14:9 10.

Mooney, H. A., 1977. Convergent Evolut ion in Chile andCalifornia Mediterranean Climate Ecosystems. Hutchinsonand Ross, Stroudsburg, Pa., 240 pp.Munsell Soil Color Charts, 1975. Determination of soil color.Munsell Color, Baltimore, MD., 32 pp.

Moore, D. M., 1983. Flora of Tierra del Fuego. Nel son,Oswestry, 396 pp.

Navas, L. E., 1973. Flora de la Cuenca de Santiago de Chile. I.Pteridophyta, Gymnospermae, Monocotyledoneae. Univ.Chile, Santiago, 301 pp.

Navas, L. E., 1976. Flora de la Cuenca de Santiago de Chile. 2.Dicotyledoneae, Archichlamydeae. Univ. Chile, Santiago,559 pp.

Oberdorfc r, E., 1960. Pflanzensoziologische Studien in Chile.Cramer, Weinheim, 208 pp.

Oliver, S. C., 1926. Lista preliminar de los mamiferos fosiles deChile. Rev. Chil. Hist. Nat., 30: 144-156.

Paskoff, R., 1970. Recherches Gfiomorphologique darts le ChiliSemi-a

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Heusser, 1990, Tagua tagua (1)