27.
NOTES ON THE
ECOLOGY OF
PORTLAND ROAD SALT M^RSH, HOBSON BAY*.
- R.L.
Bieleski.
I t i s g e n e r a l l y accepted t h a t l a r g e areas need to he s t u d i e d
i n the e l u c i d a t i o n of v e g e t a t i o n a l s u c c e s s i o n .
A great d e a l o f informa t i o n can he g a i n e d from study of s m a l l a r e a s , p a r t i c u l a r l y when the
broad p r i n c i p l e s o f the s u c c e s s i o n are a l r e a d y u n d e r s t o o d .
In t h i s
way areas even g r e a t l y m o d i f i e d by man show c e r t a i n a s p e c t s of ecology
t h a t throw l i g h t on the f a c t o r s a f f e c t i n g normal s u c c e s s i o n .
In
the example deal » w i t h here, a s m a l l s a l t marsh about 25 a c r e s i n
e x t e n t , g r e a t l y m o d i f i e d by man, was s t u d i e d ; and the e f f e c t s upon
the g e n e r a l s a l t marsh v e g e t a t i o n by f i r e , s o i l , and d r a i n a g e was
ascertained.
J
History:
The a r e a chosen was a 25 a c r e swamp and s a l t marsh
a t Remuera, bounded by P o r t l a n d Rd., Shore Rd., S c h e r f f Rd. and an
old c l i f f l i n e .
A s m a l l stream e n t e r s the landward end and the swamp
has a s m a l l system of d r a i n s t h a t passes to a t i d e gate.
Shore Rd.
c u t s o f f a l l access to the sea, a p a r t from water f l o w through the t i d e
gate i n the n o r t h - w e s t e r n c o r n e r .
Photographs o f the area t a k e n about
1900 were s t u d i e d , and the f o l l o w i n g sequence of events c o u l d be deduced.
A c l a y road was b u i l t a l o n g the c l i f f edge a t the western
s i d e from an o l d e s t a t e to meet a road t h a t went a l o n g the coast t o
the west, and a quay t h a t c r o s s e d the mouth of the marsh to the e a s t .
T h i s quay would not have n o t i c a b l y a f f e c t e d the t i d e f l o w .
Later,
however, d r a i n s were c o n s t r u c t e d and the road was extended along the
quay l i n e , c o v e r i n g i n the process most of a s h e l l bank.
Iri t h i s way,
the course of water f l o w from the swamp and marsh was a l t e r e d , f l o w i n g
out through the t i d e gate.
The d r a i n s had the e f f e c t o f (a) improving
the s o i l d r a i n a g e , ( b j g i v i n g f r e e r access of s a l t water to the upper
reaches o f the marsh, w h i l e (c) a s p e c i a l f l o r a came to occupy the
s o i l r i d g e s b e s i d e the d r a i n s .
I n the f o r m a t i o n o f the road c l a y was
t i p p e d over the mud or s h e l l bank ( p r o b a b l y the l a t t e r ) i n the n o r t h e a s t e r n c o r n e r o f the marsh; t h i s too has now a s p e c i a l f l o r a a s s o c iated with i t .
I t appears t h a t at about t h i s time S a l i x f r a g i l i s
was p l a n t e d a t the head of the marsh; l a t e r a ( l a r g e l y e x o t i c ) ground
f l o r a became a s s o c i a t e d w i t h t h i s .
The s t r o n g e x o t i c element i n the
f l o r a of t h i s marsh i s another aspect of the i n t e r f e r e n c e of man.
C o r d y l i n e was p r e s e n t i n the marsh i n 1900, but has s i n c e been ousted
by the S a l i x .
S i n c e 1900 a l s o , the a r e a covered by A v i c e n n i a o f f i c i n a l i s has i n c r e a s e d greatly, and i t appears t h a t an embryo s h e l l bank
i s i n the p r o c e s s of f o r m i n g about 70 metres out from Shore Rd.
F u r t h e r away, the c o n s t r u c t i o n between about 1925 and 1930
of the r a i l w a y embankment and Tamaki D r i v e e n c l o s e d the whole o f
Hobson Bay,
The i n c r e a s e d s i l t i n g r a t e ( i l l u s t r a t e d by the d i f f e r e n c e
of the mud l e v e l on the 2 s i d e s o f Tamaki D r i v e ) and the r a i s e d l e v e l
of the bay
has i n c r e a s e d the i n t e r t i d a l exposure of the m u d f l a t s t o >,
the stage where Z o s t e r a nana can no l o n g e r e x i s t , a l t h o u g h photographs
c o n f i r m t h a t i t was once p r e s e n t .
I n g e n e r a l i t would seem t h a t the
l i m i t f o r Z o s t e r a i s set by about 2 hours exposure a t s p r i n g t i d e ; a l l
o f Hobson Bay, except the narrow c h a n n e l , i s now exposed f o r l o n g e r
than t h i s .
I n f l u e n t i a l Factors:
The e d a p h i c f a c t o r s are the prime
moulding f a c t o r s i n the s u c c e s s i o n of a s a l t marsh.
1)
S a l t : By f a r the most i m p o r t a n t e f f e c t s are those of the s a l t
c o n c e n t r a t i o n and t i d a l i n u n d a t i o n .
Below about M.H.W.M. the s a l t
c o n c e n t r a t i o n i s kept at a s t a n d a r d l e v e l by the t i d e , and z o n a t i o n
depends on i n u n d a t i o n .
Above M.H.W.M. the s a l t c o n c e n t r a t i o n i s o f t e n
much h i g h e r t h a n t h a t of sea water, and z o n a t i o n i s c o n t r o l l e d by s a l t
concentration.
Where f r e s h water f l o w s i n t o the marsh, t h e r e i s a
b a l a n c e of f a c t o r s J s a l i n i + . v , s o i l a e r a t i o n , s o i l pH e t c .
In the
s a l i n e s o i l s of the S a l i c o r n i a meadow, the pH i s around 7.5? kept s t a b l e
*
M o d i f i e d from t#e" w i n n i n g
Memorial Prices.
e n t r y i n the 1951
Senior
Lancaster
28.
by t h e b u f f e r i n g a c t i o n o f the sea s a l t s .
I n the S a l i x swamp, the
pH can get as low as 4 . 5 .
a c c o r d i n g t o t i d a l d a t a o b t a i n e d , the main
S a l i c o r n i a meadow i s covered by the t i d e 35 to 40 times per y e a r , b u t
the v a l u e o f t h i s d a t a i s i n doubt as t h e o p e r a t i o n o f the t i d e gate
i s e r r a t i c , and t h e t i d e may inundate more f r e q u e n t l y (up t o a maximum o f 2 0 0 times a y e a r ) .
I n the mangrove community r e g u l a r i n u n d a t i o n o c c u r s , and the s a l i n i t y i s r o u g h l y t h a t o f s e a water.
On the
S a l i c o r n i a meadow i n u n d a t i o n i s i r r e g u l a r , and s a l t c o n c e n t r a t i o n can
r i s e almost t o s a t u r a t i o n (even w i t h s a l t c r y s t a l s on t h e s o i l s u r f a c e ) .
In the Juncus m a r i t i m u s community ( b e s i d e P o r t l a n d Rd.), the s a l i n i t y
i s g e n e r a l l y f a i r l y low, kept so by a slow c o u n t e r - c u r r e n t o f f r e s h
w a t e r , and t e s t s f o r s a l t are u s u a l l y o n l y b a r e l y p o s i t i v e .
2)
Soil;
The s o i l o f the g r e a t e r p a r t of the marsh i s o f c o n s o l i d a t e d
mud, h e l d by r o o t s and humus, and s u p p o r t s most o f the s a l t marsh p l a n t s ,
f o r example S a l i c o r n i a a u s t r a l i s and T r i g l o c h i n s t r i a t a .
However, i n
some areas t h e r e a r e the remains o f o l d s h e l l banks, and here t h e s o i l
i s much c o a r s e r ; S a l i c o r n i a i s r e p l a c e d by F e s t u c a arundinacea.
It is
not f e l t t h a t the" c a l c i u m i n the s h e l l bank i s t h e most s i g n i f i c a n t
f a c t o r , as c a l c i u m i o n c o n c e n t r a t i o n o f sea-water i t s e l f i s h i g h enough
to swamp any d i f f e r e n c e between the two s o i l s ( c a l c i u m s a l t s i n s e a
water = . 0 4 4 % ) .
A t the head of the marsh the mud s o i l shows an i n f l u x
of v o l c a n i c s o i l c a r r i e d down by t h e r i v e r .
T h i s has made l i t t l e d i f f erence t o the v e g e t a t i o n however, as the u n d e r c o v e r i s dominated and
determined by S a l i x f r a g i l i s w h i c h i s not a p p a r e n t l y a f f e c t e d by the
s o i l change.
i n two p l a c e s the marsh mud has been o v e r l a i d by c l a y
(by man) and here a g a i n the v e g e t a t i o n i s d i f f e r e n t from the g e n e r a l
marsh, p a r t l y from the n a t u r e o f the s o i l i t s e l f , and p a r t l y from a
r a i s i n g o f the l e v e l o f the s o i l above marsh l e v e l .
F i n a l l y , although
t h e r e i s o n l y a v e r y l i t t l e evidence f o r t h i s , . i t appears t h a t
beaches, or a sandstone s h e l f v e r y near t h e s o i l s u r f a c e .
3)
F i r e : F i r e has r e s u l t e d i n a d e f l e c t e d s u c c e s s i o n ; a burn has
o c c u r r e d r e c e n t l y on the marsh,
A s a l t marsh seems t o r e c o v e r r e l a t i v e l y r a p i d l y from a f i r e .
E a r l i e r f i r e s ( i f any) have l e f t no t r a c e .
Vegetational
Succession:
T h i s can be summarised as i n
Diagram I .
I t must be emphasised t h a t t h i s has been based on the
study o f one s m a l l s a l t marsh g r e a t l y m o d i f i e d by man.
Consequently
i t cannot be t a k e n as r e p r e s e n t a t i v e o f A u c k l a n d s a l t marshes, a l t h o u g h
most w i l l be found t o conform f a i r l y c l o s e l y t o t h i s s u c c e s s i o n .
In
t h i s schema t h e f e a t u r e o f importance i s the e f f e c t o f man on the
v e g e t a t i o n i n v a r i o u s ways.
1)
Normal S u c c e s s i o n ;
The sere i s s t a r t e d on t h e bare mud a t low
t i d e l e v e l by Z o s t e r a nana n o t p r e s e n t i n 1^he marsh, b u t i n c l u d e d i n the
schema f o r reasons a l r e a d y s t a t e d .
A v i c e i i a o f f i c i n a l i s o c c u p i e s the
u s u a l p o s i t i o n between the mid- and h i g h - t i d e l e v e l s , b e i n g a h i g h l y
dynamic community i n t h a t i t i s r a p i d l y a l t e r i n g t h e mud l e v e l by i n creased s i l t i n g , and because o f t h i s r a i s e d l e v e l i s r a p i d l y succeeded
by other p l a n t s .
A t h i g h t i d e l e v e l , above the mangrove zone, an
important p a r t i s p l a y e d by green a l g a e , p a r t i c u l a r l y two s p e c i e s o f
Enteromorpha and one o f Monostroma: i t appears t h a t t o some e x t e n t a t
l e a s t they a c t as a "nurse" to the s c a t t e r e d phanerogam c o l o n i s t s Juncus m a r i t i m u s v a r a u s t r a l i e n s i s . T r i g l o c h i n s t r i a t a v. f i l i f o r m e ,
Samolus repens and Salicornia a u s t r a l i s - i n s u p p l y i n g
humic m a t t e r ,
and a c e r t a i n amount o f p r o t e c t i o n from d e s i c c a t i o n f o r s e e d l i n g s .
In
a l l the communities so f a r mentioned, s u c c e s s i o n depends upon a r a i s i n g
o f the l e v e l o f the marsh through mud d e p o s i t i o n , which i s i n c r e a s e d
to q u i t e a degree by the presence o f the c o l o n i s t s .
Above normal h i g h
t i d e l e v e l the v e g e t a t i o n a l cover o f the marsh i s almost complete, and
has as i t s dominant S a l i c o r n i a a u s t r a l i s , w i t h T r i g l o c h i n s t r i a t a v.
f i l i f o r m e and Samolus repens s c a t t e r e d through; t h e s e t h r e e are hardy
p l a n t s , h i g h l y t o l e r a n t t o r a i t , and d e t e r m i n e d i n t h e i r d i s t r i b u t i o n
m a i n l y by c o m p e t i t i o n f o r space and l i g h t .
Mud d e p o s i t i o n can be v e r y
slow i n t h i s community, and i t has even been d e s c r i b e d as a pseudoclimax
community.
The p l a c e i n the sere o f Juncus m a r i t i m u s v. a u s t r a l i e n s i s
i n t h i s marsh i s d i f f i c u l t to e s t a b l i s h .
I t i s confined l a r g e l y to
the edge of the marsh, o r t o areas where t h e r e i s f r e s h water seepage.
I t thus appears t h a t the S a l i c o r n i a - J u n c u s s u c c e s s i o n i s decidedp r i m a r i l y by the s a l t c o n c e n t r a t i o n o f t h e s o i l , Juncus rnaritimus o c c -
Lep
29.
u r r i n g e i t h e r where t h i s i s kept down by f r e q u e n t i n u n d a t i o n or by f r e s h
water i n g r e s s .
Where Juncus m a r i t i m u s forms a community, by c o m p e t i t i o n i t s u p p r e s s e s S a l i c o r n i a , a l t h o u g h t h i s i s s t i l l a subdominant.
Juncus m a r i t i m u s may be r e p l a c e d , where f r e s h water i n g r e s s i s more
pronounced and s a l i n i t y i s low, by a S c i r p u s m a r i t i m u s community,
o f t e n w i t h Juncus m a r i t i m u s and S a l i c o r n i a a u s t r a l i s subdominant.
T h i s i n t u r n i s r e p l a c e d by Typha a n g u s t i f o l i a i n c o m p l e t e l y f r e s h
w a t e r , and t h i s i n t u r n by S a l i x f r a g i l i s .
Under the dominant cover
of S a l i x , f o u r communities e x i s t :
(a) on more open d r y ground Rubus " f r u t i c o s u s " ; (b) on more open wet ground - S c i r p u s maritimus
( w i t h Typha a n g u s t i f o l i a ) : (c) on w e l l - s h a d e d , d r y ground - a l l i u m
v i n e a l e ( w i t h Poa t r i v i a l i s ) ; (d) w e l l shaded wet ground - Ranunculus
s c e l e r a t u s , C o t u l a c o r o n i p i f o l i a and Polygonum p e r s i c a r i a .
2)
S h e l l - b a n k s u c c e s s i o n : I n the f o r m a t i o n of a s a l t m a r s h , u s u a l l y
the p r o c e s s i s s t a r t e d by the f o r m a t i o n o f an o f f - s h o r e s h e l l - b a n k , bar
or s p i t .
I n the s l a c k water between b a r and shore p r o t e c t i o n and r a p i d
s i l t i n g r e s u l t i n a s a l t marsh d e v e l o p i n g .
A second b a r , a t h i r d b a r ,
and so on, can form i n the same way i n f r o n t of such an a d v a n c i n g marsh.
In areas i n the o l d marsh where s h e l l banks have been, the p l a n t
succession f o l l o w s a d i f f e r e n t course.
To s t a r t w i t h , on the s h e l l
A v i c e n n i a does not seem t o grow w e l l ,
C o l o n i s a t i o n i s more or l e s s
s t a r t e d by Suaeda m a r i t i m a , f o l l o w e d a t a somewhat h i g h e r l e v e l or
l a t e r stage by S a l i c o r n i a a u s t r a l i s .
T h i s does n o t form a s t r o n g
community and i s r e p l a c e d by P l a n t a g o coronopus, w i t h Samolus repens
and S e l l i e r a r a d i c a n s coming i n soon a f t e r and f o r m i n g a herb community.
Under t h i s herb l a y e r the humic l a y e r i s c o n s i d e r a b l y deeper (7cm
than t h a t of the S a l i c o r n i a meadow ( 2 . 5 cm.).
Then S c i r p u s nodosus
comes i n , and t h e n T r i f o l i u m repens and F e s t u c a a r u n d i n a c e a and f i n a l l y
Plagianthus divaricatus.
The P l a g i a n t h u s i s r a r e l y a n y t h i n g more
than co-dominant w i t h F e s t u c a a r u n d i n a c e a ; Juncus m a r i t i m u s v. a u s t r a l i e n s i s i s a l s o found s c a t t e r e d t h r o u g h t h i s community.
3)
Ridge S u c c e s s i o n : Where the d r a i n s have been dug, r i d g e s o f exc a v a t e d mud have been thrown up above the l e v e l of the marsh.
Because
of t h i s s l i g h t e l e v a t i o n the community i s d i f f e r e n t , the e f f e c t b e i n g
a complex one, b a l a n c i n g f a c t o r s o f s o i l d r a i n a g e , s a l i n i t y e t c .
Where s h e l l o c c u r s a b u n d a n t l y i n the s o i l of the d i t c h r i d g e s , as i n the
s h e l l banks F e s t u c a a r u n d i n a c e a s t i l l dominates, but elsewhere on these
r i d g e s Stenotaphrum secundatum dominates (perhaps b e i n g succeeded or
r e p l a c e d by Arundo c o n s p i c u a ) and i s t h e n succeeded by U l e x europaeus
and A l b i z z i a l o p h a n t h a .
4)
C l a y Community: I n one area c l a y f i l l i n g forms the s o i l , and
here a normal weed p a s t u r e of Bromus sp. and F e s t u c a sp. i s found; t h i s
too may be succeeded by U l e x europaeus and A l b i z z i a l o p h a n t h a .
5)
The Pan S u c c e s s i o n : Both p r i m a r y and secondary pans occur on
the marsh.
I n the main, the p r i m a r y pans form a s e r i e s t h a t i n d i c a t e s
the p r e v i o u s c o u r s e of the r i v e r .
I t i s thought t h a t the course of
the r i v e r was changed by d r a i n s , and s i n c e then a c c r e t i o n and
t h i s "bed" must have been s m a l l and s h a l l o w , as the water f l o w from
the swamp i s n o r m a l l y slow.
Where t h e r e i s f r e q u e n t t i d a l i n u n d a t i o n ,
a t r u e pan does n o t e x i s t , and the s u c c e s s i o n f o l l o w s the normal c o u r s e .
In a t r u e p r i m a r y pan, w h i c h c h a r a c t e r i s t i c a l l y shows extreme v a r i a t i o n s
of s a l t c o n c e n t r a t i o n , the s u c c e s s i o n i s d i f f e r e n t , and the p r i m a r y
c o l o n i s t i s Enteromorpha ( p r o l i f e r a ? ) or R h i z o c l o n i u m h o o k e r i . Then
a b l u e - g r e e n a l g a forms a c l o s e mat over the s o i l , the decayed humus
from t h i s h e l p i n g t o p r o v i d e a seedbed.
Perhaps the a b i l i t y of some
b l u e - g r e e n algae t o f i x n i t r o g e n may be s i g n i f i c a n t .
The f i r s t v a s c u l a r p l a n t s to e n t e r are T r i g l o c h i n s t r i a t a v. f i l i f o r m e and perhaps
Cotula coronopifolia.
These are f o l l o w e d by S e l l i e r a r a d i c a n s and
Samolus repens, and f i n a l l y the more i m p o r t a n t member S a l i c o r n i a
australis*
T h i s now forms the d i s t i n c t i v e phase o f the s u c c e s s i o n
dominated by S a l i c o r n i a .
Secondary pans have formed i n s e v e r a l p l a c e s
i n one case a t l e a s t t h r o u g h the i n t e r v e n t i o n of man.
These are s t i l l
i n c r e a s i n g i n a r e a , and no r e - c o l o n i s a t i o n i s t a k i n g p l a c e .
6)
The Sand - Sandstone S h e l f S u c c e s s i o n : On the w e s t e r n s i d e of the
western d r a i n , the s u c c e s s i o n i s n o t p a r t of the main one, and communi t i e s of L e p t o c a r p u s s i m p l e x . Juncus t e n u i s and Carex d i v i s a are found.
The Carex, which i s n o r m a l l y o n l y subdominant i n the Juncus t e n u i s
community, i s c o m p l e t e l y dominant where f i r e has o c c u r r e d i n i t .
The •
30.
p l a c e i n the s e r e o f a l l these s p e c i e s i s u n c e r t a i n , and they are
perhaps dependent f o r t h e i r e x i s t e n c e on the v e r y s h a l l o w depth o f
mud (about 15-30 cm*, underneath i s the sand and sandstone ledge o f
the old-beach l i n e ) .
The mud i t s e l f i s f a r more sandy than i n the
main marsh because o f t h i s .
7)
F i r e : The S c i r p u s m a r i t i m u s - Typha s u c c e s s i o n has been a f f e c t e d
by f i r e , r e s u l t i n g i n a d e f l e c t e d s u c c e s s i o n .
The b u r n t a r e a has been
invaded, where t h e r e i s no s a l t a t a l l i n t h e s o i l , by Carex d i v i s a .
t h i s b e i n g however almost i m m e d i a t e l y succeeded by Holcus l a n a t u s and
Bromus u n i o l o i d e s .
On d r y e r ground t h i s i s f o l l o w e d by Rubus
" f r u t i c o s u s " with T r i f o l i u m repens. Bromus u n i o l o i d e s and L o t u s sp.
On swampy ground, as subdominants, N a s t u r t i u m o f f i c i n a l e , Sonchus
asper and Rumex o b t u s i f o l i u s e n t e r .
Where t h e r e a r e t r a c e s o f s a l t ,
t h e r e may be an ephemeral stage where C o t u l a c o r o n i p i f o l i a and T r i g l o c h i n s t r i a t a may form the"' r e c o l o n i s t s ; they t o o a r e r a p i d l y succeeded
by Holcus l a n a t u s and S c i r p u s maritimus.'
I n the Holcus/Bromus a s s o c i e s , S c i r p u s m a r i t i m u s i s unable t o r e g e n e r a t e , as those two form a
dense cover over t h e ground.
The Development o f the Marsh:
The d i s p o s i t i o n o f t h e p l a n t s
and s o i l s , a l o n g w i t h w h i t i s known o f the p r o c e s s o f s a l t marsh forma t i o n , l e a d s me t o the o p i n i o n t h a t t h e marsh has developed i n t h r e e
main s t a g e s , t h e r e h a v i n g been t h r e e main s e r i e s o f s h e l l b a r s , as
shown on Map I .
The f i r s t s t a g e , and f i r s t b a r p o s t u l a t e d are l a r g e l y
h y p o t h e t i c a l b u t the r e m a i n i n g two bars a r e w e l l - d e f i n e d ; and the course
of the r i v e r as p o s t u l a t e d f o r the t h i r d stage i s a c t u a l l y shown,
though p o o r l y , i n an o l d photograph.
The e x a c t course however, i s
better, shown by the p r e s e n t system of p r i m a r y pans.
The f i n a l s h e l l
bar has been l a r g e l y c o v e r e d by t h e r o a d , and o n l y c o r n e r s o f i t can
s t i l l be found.
F i n a l l y i t appears t h a t a new b a r i s d e v e l o p i n g
o f f - s h o r e , about 70 metres o u t , and i f s o , a f o u r t h s t a g e i n the formthe marsh i s s t a r t i n g .
/
MAP 1, MARSH' FORMATION
i
M
!
{i
l
31.
SERAL DIAGRAM
Albizzia
lophantha
I t i s emphasised t h a t t h i s diagram i a based
l a r g e l y on t h e s t u d y o f o n l y one s m a l l marsh.
Thus t h i s does n o t n e s s e c a r i l y r e p r e s e n t t h e
s e r e on o t h e r A u c k l a n d marshes, a l t h o u g h i t
w i l l be found t h a t much i s g e n e r a l l y a p p l i c a b l e
t o t h e s e o t h e r , o f t e n l e s s m o d i f i e d , marshes.
(Arundo
conspicua)
Ulexeuropaeus
Bromus &
Festuca
Stenotaphrum
secundatum
CLAY
RIDGE
Salix &
Rubus
MUD
RIDGE
Salix &
Allium
open
Salix &
Scirpus
maritimus
Salix &
Cotula &
Polygonum
open
V
closed
_J
i
DRY-
Plagianthus
divaricatus:
Festuca
arundinacea
Scirpus
nodosus
Samolus; &
Selliera
Plantago
coronopus
Salicornia
australis
Suaeda
maritima
Samolus &
Triglochin
SHELL BANK
SUCCESSION
Rubus—f"*\
fruticosus
-Salix
1
fragilis
i—
-WET
•T
1
?
Holcus
;
n o n — -Carex
Bromus
I
salina divisa
Bromus &
Typha
FLAT
BURNT
Festuca sp.
angustifolia
H o l c u s &s a l i n e - -Cotula &
RIDGE BURNT
T r i g l o c h i n Scirpus:
WET
maritimus
V i c i a &-ScirpusLotus
maritimus
FLAT BURNT
DRY
Juncus
tenuis &
Carex
divisa
.
Juncus
maritimus
)
Leptocarpua
simplex
Salicorniaaustralis
SAND BEACH
SUCCESSION
Juncus m a r i t i m u s
Samolus repens
Salicornia &
Triglochin
•Samolus repens &
S e l l i e r a radicans
Cotula &
Triglochin
Cyanophyceae s p .
Enteromorpha
Monostroma &
(Salicornia)
Enteromorpha o r
Rhizoclonium
Avicennia
officinalis
PRIMARY PAN
SUCCESSION
Zostera
nana
NORMAL
SUCCESSION