8/10/2019 Pole 1990 a Paleobotanist in South Westland

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A

Paleobotanist

in

South

Westland

Mikr:

Pole

Introduction

Six

days

wcrc

spellt

based

in

thc

south

westlancl

iuciL

of l-laast.'l'he

initial go

l was

to rnakc

it

taphono'ric

study

of

a

scdinrc,tary

sysr.err

where

potcntial

prant

nrircrofossils

wcrc

bcing

prcscrvcd.

A

suitablc

locality

was

not

found

but

a number

o[.bscrvations

wcr.c

.raclc

,l

palcobotanical

intctcsL,

atrd ltrc

hclpful

to

nry

stLrdics

of

thc

Enrly

Mi

8/10/2019 Pole 1990 a Paleobotanist in South Westland

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.

lakc.

l-argc lcavcd,

G

riselinia

trnd.

Aristotcliu

wcrc

pr-eseut

along

thc road or as epiphytcs.

Supplejack was

absent.

on the

poorest

soils on the high

spots

above the lake, the

forest

was

reduced to low-canopy

dominated

by

rirnu,

bog

pine,

pink

pinc

and

celery

pine.

A

day was

spcnt

in

thc

kahikttea

lorcst

bctwccn

branchcs

of the Waita

Rivcr.

I(lhikatcn

is

clonrirranl. altlrough ntatai, ntiro, rinu,

P

lLyLbcladar,

totara

(possibly

including

I'Iall's,

dc

irt)Lid,

tnd, wuiltoltcnsis) are

present.

Griselinia

is

present

as

epiplrytes.

Supplejack ancl

trcc

lirns

arc con.unorl, although the forest

floor,

in

strong

contrast to the forcst north

o[

thc

llaast l{ivcr,

is

dly, opcn, and easy to rvalk through.

Its opclt

nature

is

probably

at lcast

piflially

clue to

pcriodic

river flood

evcl)ts,

although cattle ffe

preseut

in

the iuea.

'l'he

lorest

floor

is

covcrcd

with

a

neLwolk

of

clrainagc

channels,

oftoll

just

a

fcw

centiurctlcs dcep. 1'his

systcnr

ilcts

nrostly

to flush thc littcr llom

(hc

f0rcst floor',

but was uotcd

to

lurvc

tltick littcr

dcposits

(tcns

o['

ccntinrctlcs)

krcally.

Taphonomy

ln

thc

forcst

situutions, lcavcs

[r'r>nr

all

taxa

prcscnt

iuc

wcll

rcprcscnted

in

thc lir|csL floor'

littcr

(tlrc

very

surtll lcavcs

lrour

divaricatc

sluubs were

not.

searched

fcrr).'fhc

tree fern

(Dicksonia

squttrrosa) and

the

podocarps;

I-lall's

totara, kirhikatea,

rimu,

ntiro and

natai,

all

produce

abunclant

litter which

would

be

expcctecl

to

preservc

wcll.

Paniculatc inflorcscenccs

gf

kanrahi

(Welrurra

ria

racentosa)

were

observcd

both

on surrouncling

trees and

on and within

the

floor

litter

(a

ktnrahi

inflorescence

has

bccn

rccorded

from

tlte

Manuherikia

Crouir although

lcitvcs have

no

yct

bgcrl

identiticd). Ilowcvcr',

iu

all

thc

arcirs wherc

pltnt

urateritl

w1s

accunrulating

-

in

thc mires and in pools

within

the swarnp forest,

well

plcserved

plant

n.]aterial

is present

only

on

the surface centinretre

0r

two.

Beside

this,

leaves und shoots have

decayecl

artd

txtly

lttudcr

utatedal,

such

as

wood, is

preserved.

It is

clear

that

in

these'iu situ'litter

accttnlttlatiotts,

a

dran)atic

influx

of

scdiment

would

be

necessaty

to

relnove

litter

lrom

the

zonc

of soil

dcvclopnrcut

and

provide

lor

their

krlg-teflu

preservation.

Vegetation

History

My

work

on

the

Ear{y

Miocene

Manuherikia

Croup,

in

addition

to

that

of

other workers,

has

lead me

to believe that

the

present

flora

of

New Zealaud,

from

an

assemblage

point

of

view,

is

o['recent,

probably

Pleistocene

age, ancl

is

an

inrpoverished

relict

of

tlre

Tcrtiary

flora.

The

lack

of

thamatic

changc between

present

rkrlas

growing

on

granite or

alluviirl

soils,

or even

Llc[vcert

tlxlse

gcncrally

itupoverishecl

soils on

the West

Coast, and the

rich

blslltic

soils

rround

Dunedin,

suggest

that,

with

n lew

exceptions rcccnt

taxa

could

be

accordctl'wecd'

status.

'l'hcy

iue survivofs

01'thc

icc-ugcs,

or

perhaps

non-specialiscd

proclucts

of rcccnt

cvolution.

-fhey

arc opporttrnists ancl piouccr

types

which

can'stick

it

out'

in rclugia

and

quickly

colonise a variety