Evidence for changes in Holocene vegetation and lake sedimentation in the Markham Valley, Papua New Guinea

E V I D E N C E F O R CHANGES I N HOLOCENE VEGETATION AND LAKE SEDIMENTATION I N THE MARKHAM VALLEY, PAPUA NEW G U I N E A

by

SAMUEL EDWARD GAFSETT-JONES

T h e s i s s u b m i t t e d f o r t h e degree of D o c t o r of Philosophy a t t h e A u s t r a l i a n N a t i o n a l U n i v e r s i t y

3

FRONTISPIECE. Lake Wanum, Morobe Province, Papua New Guinea.

CONTENTS CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAF'TER CHAPTER CHAPTER CHAPTER APPENDIX APPENDIX

APPENDIX I11 APPENDIX I V

ABSTRACT

L I S T OF FIGURES L I S T OF TABLES L I S T O F PLATES ACKNOWLEDGEMENTS INTRODUCTION

THE MARKHAM VALLEY

SWAMP AND LACUSTRINE D E P O S I T S OF THE LAKE WANUM AREA

SWAMP AND LACUSTRINE D E P O S I T S OF YANAMUGI

HERBACEOUS SWAMP VEGETATION OF THE MARKHAM VALLEY

THE DETERMINATION OF POLLEN AND CHARCOAL DEPOSITION RATES

CONTEMPORARY POLLEN D E P O S I T I O N I N THE MARKHAM AREA

INTERPRETATION OF VEGETATION CHANGE FROM POLLEN ANALYTICAL DATA

HOLOCENE VEGETATION AND ENVIRONMENTAL CHANGE I N THE MARKHAM VALLEY AND OTHER TROPICAL REGIONS

I D E N T I F I C A T I O N AND D E S C R I P T I O N OF POLLEN AND SPORE TAXA RECORDED FROM MARKHAM VALLEY CORES AND SURFACE SAMPLES

THE ALLOCATION OF POLLEN XgD S P ( j m TAXA TO ECOLOGICAL GROUPS

POLLEN ANALYTICAL DATA COMPUTER PROGRAMS BIBLIOGRAPHY

P a g e

5 7 1 0 1 2 1 3 1 5 2 6

4 5

9 3

1 3 2

1 5 8

1 7 5

203

269

290

361

The p a s t s t a b i l i t y of v e g e t a t i o n p a t t e r n s i n t h e Markharn V a l l e y ( 6 ° 3 0 ' ~ , 1 4 6 ° 3 0 ' ~ ) , a lowland g r a s s l a n d a r e a of Papua New Guinea, i s i n v e s t i g a t e d by p o l l e n a n a l y s i s of l a k e d e p o s i t s and r e l a t e d p a l a e o e c o l o g i c a l techniques.

The predominantly o r g a n i c sediments of Lake Wanum ( a l t . 35 m) span t h e l a s t 9600 y e a r s . A 1 4 C chronology s u p p o r t s t h e c a l - c u l a t i o n of annual p o l l e n d e p o s i t i o n , sediment accumulation, and carbonised p a r t i c l e i n f l u x r a t e s . A t Yanamugi l a k e ( a l t . 170 m ) ,

1 4 C a s s a y s o f t h e c a l c a r e o u s muds a r e i n f l u e n c e d by v a r i a b l e 'hard- w a t e r e r r o r ' . A t e n t a t i v e chronology i s based on palaeomagnetic and t e p h r a c o r r e l a t i o n s .

P o l l e n t r a p p i n g r e v e a l s very h i g h contemporary annual d e p o s i t i o n r a t e s w i t h i n f o r e s t , b u t low v a l u e s over t h e c e n t r a l l a k e a r e a . S u r f a c e p o l l e n assemblages from d i f f e r e n t h a b i t a t s i n d i c a t e t h e l o c a l i s e d n a t u r e of p o l l e n d i s p e r s a l , although a r e l a t i v e l y

' l o n g - d i s t a n c e component' from h i g h e r a l t i t u d e s i s a l s o recognised. Analysis of f l o r i s t i c d a t a from t h e herbaceous swamp v e g e t a t i o n of Lake Wanun s u g g e s t s t h e e x i s t e n c e of two f r e e

f l o a t i n g root-mat a s s o c i a t i o n s and two o r t h r e e r o o t e d a s s o c i a t i o n s Water depth a p p e a r s t h e primary c o n t r o l on t h e i r d i s t r i b u t i o n .

subsequently (3000 BP t o 2000 BP) come t o dominate t h e s i t e . A g e n e r a l t r e n d towards i n c r e a s e d water depth i s i n d i c a t e d throughout t h e sequence.

I n c r e a s e d r e p r e s e n t a t i o n of dry-land n o n - f o r e s t p o l l e n o c c u r s from 8550 BP, and g r a s s l a n d t a x a become more f r e q u e n t from &out 5350 R P . S y n c h r m ~ u s trends i n carbonised p a r t i c l e i n f l u x i d e n t i f y f i r e a s a probable a g e n t of v e g e t a t i o n change.

L i t t l e change i n dry-land v e g e t a t i o n i s recorded i n t h e p o l l e n sequence from Yanamugi, although r e c e n t encroachment by swamp v e g e t a t i o n occurs. The l a r g e p r o p o r t i o n of 'montane' p o l l e n and s p o r e t a x a i n t h e e a r l i e r sediments i s a t t r i b u t e d t o v a r i a b l e f l u v i a l i n f l u x .

L I S T FIGURES

Title Page

2 7

2 8

3 2

2 2 d 4 T h e Markham V a l l e y : P h y s i o g r a p h y

T h e Markham V a l l e y : G e o l o g y

T h e Markham V a l l e y : R a i n f a l l

T h e r a i n f a i i r e g i m e o f s e i e c t e d Markham v a i l e y s t a t i o n s

T h e Markham V a l l e y : M a j o r v e g e t a t i o n t y p e s

T h e d i s t r i b u t i o n o f l a k e s and swamps i n t h e L a k e Wanum a r e a

L a k e Wanum: B a t h y m e t r i c sketch map

L a k e Wanum: S k e t c h map s h o w i n g the l o c a t i o n o f c o r i n g s i t e s

Key t o s t r a t i g r a p h i c d i a g r a m s

R e d h i l l Swamp: S t r a t i q r a p h y o f cores RHA 1 and RHB 1

L a k e Wanum: S t r a t i g r a p h y o f cores i n north-

e a s t b a y T r a n s e c t A

L a k e Wanum: S t r a t i q r a p h y o f cores i n north-

e a s t b a y T r a n s e c t B

L a k e Wanum core LW 11: W a t e r content and w e i g h t l o s s on i g n i t i o n

L a k e Wanum core LW I I : S e d i m e n t d e n s i t y f o r r e s i d u e - ( ' i n o r g a n i c ' ) and l o s s - o n - i g n i t i o n

( ' o r g a n i c ' ) f r a c t i o n s

L a k e V m z m c o r e LW 11: A g e / d e p t h p r o f i l e s fir

( a ) u n c o r r e c t e d

14c

14c

L a k e Wanum c o r e LW I I : A v e r a g e s e d i m e n t a c c u m u l a t i o n r a t e s . ( a ) R a t e ' A ' ( b ) R a t e ' B '

( c ) R a t e ' C '

L a k e Wanum c o r e LW 11: G r a v i m e t r i c s e d i m e n t d e p o s i t i o n r a t e s b a s e d on a c c u m u l a t i o n r a t e ' A '

LIST OF FIGURES

Title Page

S k e t c h map o f the Y a t s i n g a r e a 9 4 Yanamugi: B a t h y m e t r y and c o r e l o c a t i o n s 9 6 Yanamugi: G e n e r a l i s e d s t r a t i g r a p h y 9 9 Yanamugi core YAN 2 : W a t e r c o n t e n t and w e i g h t 104

l o s s on i g n i t i o n

Yanamugi c o r e YAN 2: S e d i m e n t d e n s i t y f o r 105 r e s i d u e - ( ' i n o r g a n i c ' ) and l o s s - o n - i g n i t i o n

( ' o r g a n i c ' ) f r a c t i o n s

Yanamugi c o r e YAN 2 : ( a ) NRM i n t e n s i t y 109 m e a s u r e m e n t s n o r m a l i s e d on the b a s i s o f d r y

w e i g h t . (b) N o r m a l i s e d NRM i n t e n s i t y versus i n o r g a n i c s e d i m e n t d e n s i t y

Y a n a m u g i : P a l a e o m a g n e t i s m o f short cores 110 YANMC 1 and YANMC 2

Y a n a m u g i : P a l a e o m a g n e t i s m o f l o n g cores YAN 1 111-

and YAN 2 112

Y a n a m u g i : R a d i o c a r b o n d e t e r m i n a t i o n s and 119 i n f e r r e d a g e / d e p t h p r o f i l e

Dendrogram o f s u m s - o f - s q u a r e s a n a l y s i s o n 136 f l o r i s t i c d a t a f r o m L a k e Wanum, n o r m a l i s e d b y

q u a d r a t

Dendrogram o f s u m s - o f - s q u a r e s a n a l y s i s on 14 1 f l o r i s t i c d a t a from L a k e Wanum, n o n - n o r m a l i s e d

Dendrogram o f s u m s - o f - s q u a r e s a n a l y s i s o n 142 f l o r i s t i c d a t a f r o m L a k e Wanum, common t a x a

o n l y , n o r m a l i s e d b y q u a d r a t

C o v e r - a b u n d a n c e o f common h e r b a c e o u s swamp 146 t a x a f r o m L a k e Wanum i n r e l a t i o n t o w a t e r

d e p t h

Major e c o i o g j c a i '-Jroups represented in

c o n t e m p o r a r y p o l l e n s a m p l e s

C o n t e m p o r a r y p o l l e n s p e c t r a ( s e l e c t e d t a x a ) from h e r b a c e o u s swamp s i t e s

LIST OF FIGURES

Title

L a k e Wanum c o r e LW 11: P o l l e n d e p o s i t i o n r a t e s (PDR) f o r m a j o r g r o u p s , c a r b o n i s e d p a r t i c l e and s e d i m e n t a c c u m u l a t i o n r a t e s

Page

209

L a k e Wanum c o r e LW 11: PDR for h e r b a c e o u s 2 10 swamp p o l l e n and S-pore t a x a

Lake Wanum c o r e LW 11: R e l a t i v e f r e q u e n c y 211 d i a g r a m f o r h e r b a c e o u s swamp p o l l e n and s p o r e

t a x a

S c h e m a t i c H o l o c e n e w a t e r d e p t h r e c o r d f o r the 223

s i t e o f core LW 11

L a k e Wanum core LW 11: PDR o f selected d r y 229- l a n d p o l l e n and s p o r e t a x a 231

Yanamugi c o r e YAN 2: P o l l e n c o n c e n t r a t i o n o f 249 m a j o r e c o l o g i c a l g r o u p s , and f r e q u e n c y o f

c a r b o n i s e d p a r t i c l e s

Yanamugi core YAN 2: R e l a t i v e f r e q u e n c y 250- d i a g r a m f o r s e l e c t e d p o l l e n and s p o r e t a x a 253

LIST OF TABLES

S h o r t t i t l e

S t r a t i g r a p h i c d e s c r i p t i o n o f c o r e LW II

R a d i o c a r b o n d e t e r m i n a t i o n s f r o m L a k e Wanum

Comparison o f a v e r a g e s e d i m e n t a t i o n r a t e s ( c o r e LW II)

S t r a t i g r a p h i c d e s c r i p t i o n o f core YAN 2

R a d i o c a r b o n d e t e r m i n a t i o n s f r o m Yanamugi

R e l a t i v e and a b s o l u t e s e d i m e n t a t i o n r a t e s f o r t h e l a s t 275 y e a r s

C o m p a r i s o n o f s e d i m e n t a t i o n r a t e s i n c o r e s

YAN 1 and YAN 2 p r i o r t o 1 7 0 0 A.D.

F 1 o r i s t i c d a t a f r o m h e r b a c e o u s swamp q u a d r a t s a t L a k e Wanum

H e r b a c e o u s swamp d a t a m a t r i x grouped b y s u m s - o f - s q u a r e s a n a l y s i s

Summary o f p r e p a r a t i o n t e c h n i q u e s

R e s u l t s o f r e p l i c a t e c o u n t s o n s l i d e s c o n t a i n i n g d i f f e r e n t v o l u m e s o f Lycopodium c l a v a t u m s u s p e n s i o n

C o m p a r i s o n o f r e s u l t s w i t h t h o s e e x p e c t e d f r o m the g i v e n content o f t h e s p o r e t a b l e t s

C o n t e m p o r a r y p o l l e n s a m p l e s f r o m the Markham V a l l e y

A n n u a l p o l l e n and s p o r e d e p o s i t i o n r a t e s e s t i m a t e d from p o l l e n t r a p s

C o m p a r a t i v e a i r b o r n e p o l l e n and s p o r e d e p o s i t i o n r a t e s f r o m o t h e r a r e a s

P o l l e n - and s p o r e - m o r p h o l o g i c a l g r o u p s r ~ c n g n i s e d a n d their r e p r e s e n t a t i o n - - - -

T h e e c o l o g y o f p l a n t s c o n t r i b u t i n g t o the p o l l e n and s p o r e t a x a

I d e n t i f i e d p o l l e n and s p o r e t a x a i n c l u d e d i n

Page

56-58

6 7

78

100-101

118

1 2 7

128 135 137 165 170 170 177- 178

1 8 2

19 7

293

363- 373

373-

L I S T OF TABLES

S h o r t t i t l e Page

111.1 Pollen and s p o r e c o u n t s from c o n t e m p o r a r y 376-

s u r f a c e s a m p l e s 3 78

I I I . 2 Pollen and s p o r e c o u n t s from p o l l e n t r a p s 379-380

111.3 P o l l e n and s p o r e c o u n t s from Yanamugi 381-

Core YAN 2 385

I I I . 4 P o l l e n and s p o r e c o u n t s from L a k e Wanum 386-

Core LW 11 390

I I I . 5 F a c t o r s f o r p o l l e n and s p o r e c o u n t s from 392 p o l l e n t r a p s

I I I . 6 F a c t o r s for p o l l e n and s p o r e c o u n t s from 392 Yanamugi C o r e YAN 2

LIST OF PLATES

S h o r t t i t l e Page

FRONTISPIECE. Lake Wanum, Morobe Province, 3 Papua New Guinea.

The Erom-Erom l a k e s and Lake Wanum, an o b l i q u e 4 8 a e r i a l view from t h e south-west.

The e a s t e r n shore of Lake Wanum, an o b l i q u e 48 a e r i a l view from t h e n o r t h .

Yanamugi l a k e , an o b l i q u e a e r i a l view from t h e 95 e a s t .

Yanamugi l a k e from t h e south. 95

The e x t e n s i v e s o u t h swamp of Lake Wanum. 144 Hypolytrum nemorum and Stenochlaena p a l u s t r i s 144 encroaching on open water s t a n d s of Nelumbo

n u c i f e r a , s o u t h swamp, Lake Wanum.

F l o a t i n g root-mat v e g e t a t i o n i n deep water a t 145 t h e western margin of t h e n o r t h - e a s t bay, Lake

Wanum.

Aquatic v e g e t a t i o n a t t h e n o r t h e r n end of 145 Y anamugi

.

ACKNOWLEDGEMENTS

Papua New Guinea and A u s t r a l i a were e q u a l l y unknown t e r r i t o r i e s t o m e b e f o r e I undertook t h i s p r o j e c t . I am e v e r

i n d e b t e d t o t h o s e i n both c o u n t r i e s who provided me t h e o p p o r t u n i t y t o s h a r e both t h e i r p r e s e n t and t h e i r p a s t .

P r o f e s s o r Donald Walker, my s u p e r v i s o r , guided me towards, and through, t h i s study. I thank him f o r h i s continued i n t e r e s t , p a t i e n c e , and championship of t h e cause of p e l l u c i d i t y o v e r

o b f u s c a t i o n .

I am g r a t e f u l f o r t h e c o o p e r a t i o n of numerous Papua New Guinea Government i n s t i t u t i o n s and i n d i v i d u a l s . The D i v i s i o n of Botany, Lae, provided c o n s i d e r a b l e l o g i s t i c and f l o r i s t i c s u p p o r t under s u c c e s s i v e A s s i s t a n t D i r e c t o r s , M r J.S. Womersley,

M r Ted Henty (Acting A s s i s t a n t D i r e c t o r , 1976) and M r Michael Galore. A s s i s t a n c e was a l s o r e c e i v e d from t h e Dept of F o r e s t s , Lae,

Joe Glucksman of t h e F i s h e r i e s Research D i v i s i o n , Dept of

A g r i c u l t u r e , Stock and F i s h e r i e s , Konedobu, and t h e D.A.S.F. Land U t i l i s a t i o n D i v i s i o n , Boroko. Bob Johns, P.N.G. F o r e s t r y College, Bulolo, k i n d l y allowed me a c c e s s t o h i s unpublished d a t a . I

p r o f i t e d from d i s c u s s i o n s w i t h t h e v a r i o u s members of t h e U n i v e r s i t y of Papua New Guinea, P o r t Moresby, and t h e U n i v e r s i t y of Technology, Lae

.

Fieldwork would have been i m p o s s i b l e without t h e h e l p and h o s p i t a l i t y of many P a p a New Guineans. Gamman and his w a n t o k s f r o m Gabensis provided l a b o u r a t Lake Wanum. A t Yanamugi, Nafwan and t h e o t h e r Yatsing v i l l a g e r s were kind h o s t s and w i l l i n g h e l p e r s .

I thank t h e assembled members of t h e Dept of Biogeography and Geomorphology, almost a l l of whom have helped o r advised. I n p a r t i c u l a r , Daphne Moss and Joan Guppy f o r a s s i s t a n c e w i t h p o l l e n i d e n t i f i c a t i o n , Alan McDonell f o r g e t t i n g equipment from A t o B f a s t e r than p o s s i b l e , Neal E n r i g h t f o r running t h e v e g e t a t i o n a n a l y s i s p r e g r m s , and Er Geoff Hope f o r h i s i n f e c t i o u s enthusiasm about a l l t h i n g s New Guinean. D r I a n Raine e x p l a i n e d h i s computer programs t o m e , w h i l s t D r P e t e r Kershaw (Monash U n i v e r s i t y ) and D r John F l e n l e y could always be r e l i e d on f o r thought provoking i d e a s .

Elsewhere a t A . N . U . , t h e f a c i l i t i e s of t h e Research School of E a r t h Sciences were used f o r palaeomagnetism a n a l y s i s .

C h a r l e s Barton a s s i s t e d c o n s i d e r a b l y , and provided t h e computer programs t o p l o t F i g s . 4.7 and 4.8. A l l radiocarbon samples were assayed by t h e A.N.U. Radiocarbon Laboratory. Much time was s p e n t by Yvonne P i t t e l k o w , J o i n t Schools' Computer S e r v i c e s , i n b r i d g i n g t h e chasm of t h e 'man/machine i n t e r f a c e ' .

P l a n t c o l l e c t i o n s were i d e n t i f i e d by M r R. P u l l e n and D r L. Craven t h e Herbarium A u s t r a l i e n s e , Commonwealth S c i e n t i f i c and I n d u s t r i a l Research O r g a n i s a t i o n . D r R u s s e l l Blong, Macquarie

U n i v e r s i t y , t r a c k e d down t h e t e p h r a s . The whole t h i n g was p a i n s t a k i n g l y typed by Lesley Kendall, and Joan Guppy f i n a l l y

' g o t it a l l t o g e t h e r ' .

The s t u d y was f i n a n c e d by t h e A u s t r a l i a n N a t i o n a l

U n i v e r s i t y w h i l e I was i n r e c e i p t of a Commonwealth S c h o l a r s h i p and Fellowship Plan s c h o l a r s h i p from t h e A u s t r a l i a n Government.

To everyone who h a s eased this t h e s i s , i n any way a t a l l , towards i t s u l t i m a t e d e s t i n a t i o n ,