by of Doctor of Philosophy at the by lindahy

VIEWS: 33 PAGES: 14

More Info
									EVIDENCE F O R CHANGES I N HOLOCENE VEGETATION AND LAKE
SEDIMENTATION I N THE MARKHAM VALLEY, PAPUA NEW GUINEA




                              by



             SAMUEL EDWARD GAFSETT-JONES




           T h e s i s s u b m i t t e d f o r the degree
           of    D o c t o r of Philosophy a t t h e
           Australian National University


           Canberra                    O c t o b e r 1979
                                                                 3




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

  Oblique aerial view from the north-west, 8 October 1974.
                         CONTENTS


                                                          Page


                ABSTRACT                                     5

                L I S T OF FIGURES                           7

                L I S T OF TABLES                           10

                L I S T OF PLATES                           12

                ACKNOWLEDGEMENTS                            13

CHAPTER         INTRODUCTION                                15

CHAPTER         THE   MARKHAM VALLEY                        26

CHAPTER         SWAMP AND LACUSTRINE DEPOSITS OF THE       45
                LAKE WANUM AREA

CHAPTER         SWAMP AND LACUSTRINE DEPOSITS OF           93
                YANAMUGI

CHAPTER         HERBACEOUS SWAMP VEGETATION OF THE        132
                MARKHAM VALLEY

CHAF'TER        THE DETERMINATION OF POLLEN AND           158
                CHARCOAL DEPOSITION RATES

CHAPTER         CONTEMPORARY POLLEN DEPOSITION I N THE    175
                MARKHAM AREA

CHAPTER         INTERPRETATION OF VEGETATION CHANGE       203
                FROM POLLEN ANALYTICAL DATA

CHAPTER         HOLOCENE VEGETATION AND ENVIRONMENTAL     269
                CHANGE I N THE MARKHAM VALLEY AND OTHER
                TROPICAL REGIONS

APPENDIX        IDENTIFICATION AND DESCRIPTION OF         290
                POLLEN AND SPORE TAXA RECORDED FROM
                MARKHAM VALLEY CORES AND SURFACE
                SAMPLES

APPENDIX        THE ALLOCATION OF POLLEN XgD S P ( j m    361
                TAXA TO ECOLOGICAL GROUPS

APPENDIX I11    POLLEN ANALYTICAL DATA                    376

APPENDIX   IV   COMPUTER PROGRAMS                         39 4

                BIBLIOGRAPHY                              404
                 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

                                                                                         e
Valley ( 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 N w

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 ) ,

14C assays o f t h e calcareous muds a r e i n f l u e n c e d by v a r i a b l e 'hard-

water 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 high 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

area.       Surface 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

'long-distance component' from higher 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 rooted a s s o c i a t i o n s

Water depth appears 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 .

                Holocene swamp communities analogous with e x t a n t a s s o c i -

a t i o n s may be i d e n t i f i e d i n t h e p a l y n o l o g i c a l record of Lake Wanum.

Swm~pl ~ l a r g i n a conditic?~.:pzesrail from 9500 R P u n t i l 8200 BP when
                       l

permanent shallow water becomes e s t a b l i s h e d .                   Rooted v e g e t a t i o n

a s s o c i a t i o n s then predominate u n t i l about 5000 BP.                  Floating

v e g e t a t i o n a s s o c i a t i o n s f i r s t become important a t t h i s t i m e , and
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.

              Increased r e p r e s e n t a t i o n of dry-land non-forest p o l l e n

occurs 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 RP.       S y n c h r m ~ u strends 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 agent 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 spore 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 influx.

              Conditions a t Lake Wanum u n t i l 8200 BP may r e f l e c t t h e

e a r l y Holocene a r i d i t y widespread i n e q u a t o r i a l a r e a s , although t h e

i n d i r e c t hydrologic e f f e c t s of r i s i n g s e a l e v e l cannot be d i s -

counted.      Human impact appears t h e main determinant of dry-land

v e g e t a t i o n change during much of t h e Holocene.
                         LIST          FIGURES


                                    Title                                             Page

 T h e Markham V a l l e y :         Physiography                                      27

 T h e Markham V a l l e y :         Geology                                           28

 T h e Markham V a l l e y :         Rainfall                                          32

                                                                                       22
 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             d 4



 stations

 T h e Markham V a l l e y :         Major 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 the
 Lake Wanum a r e a

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

Lake 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 sites

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 bay Transect 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 bay Transect B

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

Lake Wanum core L I I : S e d i m e n t d e n s i t y f o r
                              W
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
('organic') fractions

L a k e V m z m c o r e L 11: A g e / d e p t h p r o f i l e s fir
                            W
( a ) u n c o r r e c t e d 14c d a t e s and ( b ) r e c a l i b r a t e d
14c d a t e s
                               W
L a k e Wanum c o r e L 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 '

                              W
L a k e Wanum c o r e L 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'

L a k e Wanum core LW II: 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 ' C '
                            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                                      94

 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              96

 Yanamugi:           Generalised stratigraphy                                       99

 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
 ('organic') fractions

Yanamugi c o r e YAN 2 : ( a ) N M i n t e n s i t y
                                               R                                   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
weight.          (b) N o r m a l i s e d NRM i n t e n s i t y versus
inorganic sediment d e n s i t y

Yanamugi: 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

Yanamugi:           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

Yanamugi: 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 age/depth 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 from Lake Wanum, n o r m a l i s e d b y
quadrat

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                    141
f l o r i s t i c d a t a from Lake 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 , normalised b y quadrat

Cover-abundance 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
depth
Major e c o i o g j c a i '-Jroups represented                    in
contemporary p o l l e n samples

Contemporary 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

C o n t e m p o r a r y p01 l en s p e c t r a ( s e l e c t e d t a x a )
f r o m non-swamp s i t e s
                        LIST OF FIGURES


                                  Title                                        Page

                           W
Lake Wanum c o r e L 11: P o l l e n d e p o s i t i o n                       209
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

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

Lake Wanum c o r e L 11: R e l a t i v e f r e q u e n c y
                            W                                                  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
taxa

S c h e m a t i c Holocene 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 L 11W

Lake Wanum core L 11: PDR o f selected d r y
                        W                                                      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
carbonised 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

S i z e - c l a s s d i s t r i b u t i o n o f p o l l e n g r a i n s from   296
some common g r a s s s p e c i e s
                       LIST OF TABLES


                              Short t i t l e                                Page

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 L II
                                                             W                56-58

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 Lake Wanum          67

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              78
          W
( c o r e L 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               100-101

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           118

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      1 27
f o r the l a s t 275 y e a r s

Comparison 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            128
YAN 1 and YAN 2 p r i o r t o 1700 A.D.

F1 o r i s t i c d a t a from h e r b a c e o u s swamp q u a d r a t s     135
a t Lake Wanum

Herbaceous swamp d a t a m a t r i x grouped b y                            137
sums-of-squares 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                       165

Results o f replicate counts on s l i d e s                                 170
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
clavatum suspension

Comparison 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      170
the g i v e n content o f the s p o r e t a b l e t s

Contemporary p o l l e n s a m p l e s f r o m the Markham                  177-
Valley                                                                      178

Annual 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              182
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             19 7
d e p o s i t i o n r a t e s from 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         293
- - -c n g n i s e d and their r e p r e s e n t a t i o n
r~ -

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         363-
p o l l e n and s p o r e t a x a                                           373

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   373-
e c o l o g i c a l groups                                                  375
                            L I S T OF TABLES


                                  Short 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 samples                                                 3 78

III.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

III.4   P o l l e n and s p o r e c o u n t s from Lake Wanum                 386-
        Core L 11 W                                                           390

III.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
        pollen traps

III.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

III.7   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 Lake   393
        Wanum C o r e L 11  W
                  LIST OF PLATES


                         Short 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 oblique                 48
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 north.


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
east.

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


The e x t e n s i v e south 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 , south 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   .

Photomicrographs of p o l l e n and s p o r e t a x a from        329-
Markham Valley sediment c o r e s and contemporary                360
assemblages.
                                     C N WE GMNS
                                    AK O LD E E T


                 Papua New Guinea and A u s t r a l i a were equally 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 ever

                                                                e
indebted t o t h o s e i n both c o u n t r i e s who provided m t h e opportunity

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 .

                                                  y                              e
                P r o f e s s o r Donald Walker, m s u p e r v i s o r , guided m 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 over

obfuscation.

                   m
                I a g r a t e f u l f o r t h e cooperation 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 Division 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 support

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.

Assistance was a l s o received 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,

                             e
Bulolo, k i n d l y allowed m 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 various members of t h e U n i v e r s i t y

          e
of Papua N w 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 impossible 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 labour 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 .

J i m C r o f t and Neal E n r i g h t a l s o a s s i s t e d i n 'mini-Mackereth'             coring

during 1976.
                 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.                                      In

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 Enright 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 explained 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 Flenley could always be r e l i e d on f o r thought provoking

ideas.

                 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 .

Charles Barton a s s i s t e d considerably, 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 Organisation.                 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 study was financed by t h e A u s t r a l i a n National

University while I was i n r e c e i p t of a Commonwealth Scholarship 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 has 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 ,

                                                        Tenkyu tumas!

								
To top