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Saltmarshes and WFD

In The Netherlands

Jan. M. Reitsma([email protected])

Contents

• Saltmarshes in The Netherlands –an

overview

• Data acquisition and Method of

monitoring

• WFD Metric for Salt marshes

• Pressure gradients

Saltmarshes in The Netherlands –an overview

Waterbodies:Waddensea (CW-K2)

Oosterschelde (CW-K2)

Northsea Wadden Islands (CW-K3)

Northsea West Coast (CW-K1)

Eems-Dollard (TW-O2)

Westerschelde (TW-O2)

Saltmarshes:Waddensea – mainland (partly artificail

with groynes); clay

Waddensea barrier islands: sandy

Northsea coast: washovers, green

beaches (sandy)

Oosterschelde (clay)

Eems-Dollard & Westerschelde: partly

brackish marshes

Saltmarshes in The Netherlands –an overview

Mainland saltmarshes: clayish, mainly artificial

(land reclamation trough groynes and

dikes), drainage systems are still

maintained, large parts are grazed

Saltmarshes on the Wadden Islands: sandy,

natural drainage systems, transitions

between salt marshes, dune slacks and dry

dune communities, on the lee-side of the

islands

North sea coast: sandy, ‘wash-overs’’, green

beaches, contact zones with fresh water

communities; a few sites along the coast

Oosterschelde: clayish, low tidal amplitude

(seaside barrier);

Westerschelde + Dollard: brackish (partly),

reedvegetation + Scirpus maritimus,

polyhalien near the mouth. In

Westerschelde extensive areas of Spartina

(pioneer zone)

10750total

750TWEems-Dollard

2400TWWesterschelde

500CWOosterschelde

530CWNorth sea coast

3150CW

Waddensea - barrier

islands

3420CW

Waddensea -

mainland

area saltmarsh

(ha)

Data acquisition & compilation – method of monitoring

General:

All salt marshes are mapped every 5-6 yearson a scale 1:5,000 or 1:10,000

This is done since ca. 1980

The method used has been fairly consistent

Therefore results are well comparablethroughout the years

All results are stored in a database (GIS) atDID, Delft (Rijkswaterstaat; Ministry ofPublic Works) and can be consulted onrequest

A fixed typology (SALT’08) is used; allsaltmarsh vegetation is fit into thistypology (ca. 80 different types. Based onseveral thousands of BB-vegetionrelevees)

For the Waddensea area a common typologyhas been developed together withGermany and Denmark: TMAP (TrilateralMonitoring and Assessment Program)

SALT’08 types can be translated directly intoTMAP (the latter being less detailed)

TM A P-nr TM AP co de Nam e

hea dzo ne type

0 S u No in fo rm ation about zone and vegetat ion t yp

0.0 S u* Salt / b rackish landscape, unspe cif ic

0.1 S w bare water

0.2 S s bare soil, sand (beaches etc . .)

0.3 S m bare soil, m udf lat

1 S P Pioneer s alt ma rsh

1.0 S P* Pionier sa lt m arsh, unspec if ic

1.1 S Ps Spart ina anglica type

1.2 S Pq Salicornia sp p. / S ua eda m arit im a type

2 S L Lo w M arsh

2.0 S L* Low M arsh, unspec if ic

2.1 S Lp Pucc inellia m arit im a type

2.2 S Ll Lim onium vulgar e / Pucc ine llia m ar itim a type

2.3 S La Aster t ripolium / Pucc inellia ma rit im a typ e

2.4 S Lh Atr iplex portulacoides / Pucc inellia m arit im a typ e

3 S H High marsh

3.0 S H * Hig h M arsh, unspec if ic

3.1 S H l Lim onium vulgar e / Juncus gera rdi typ e

3.2 S H j Juncus g erard i / Glaux m arit im a type

3.3 S H f Fes tuca r ubra type

3.4 S H h Atr iplex portulacoides / Artem is ia m arit im a type

3.5 S H z Artem isia m ar itim a / Fes tuca rubra typ e

3.6 S H m Juncus m a ritim us / F es tuca rubra / Juncus gerard i typ e

3.7 S H y Elym us a ther icus type

3.8 S H e Car ex ex te nsa type

3.9 S H x Atr iplex pros trata / Atriplex littoralis type

3.10 S H g Agros t is s tolonife ra / T rifolium frag ifer um type

3 .11 S H c Planta go coronopus / C enta urium lit torale type

3.12 S H o Ononis spinosa / C arex dis tans type

3.13 S H r Elym us r epens type

4 S G Green beach , sa ndy pione er

4.0 S G * Sandy gr een beach, unspec if ic

4.1 S / D G f Elym us far ctus type

5 S B Brackish marsh

5.0 S B* Brack ish m arsh, unspec if ic

5.1 S Bb Bolboschoenus + Schoenoplec tus type

5.2 S Bp Phragm ites a ustralis type

5.4 S Bg Brack ish f looded gra ssland type

5.5 S Bm Juncus m a ritim us / Oena nthe lachenalii type

6 S F Fresh (an thropogen ic) g rassland

6.0 S F * Fre sh (anthropog enic ) ve getatio n, unspec ific

6.1 S F l Lolium pe renne, C yn osur us c ris tatus and other fresh spec ies type

TM AP legen d o f salt and b rackish vegetation

Data acquisition – method of monitoring

Airial survey, interpretation

Method in a nutshell

- Aerial surveys in the summer (growing

season), using mostly false colour

photographs

- Interpretation and digitizing in winter using

ArcInfo, DFS (Digital Fotogrammetric

System combined with Summit Evolution

(polygon minimum is 20 x 20 m, relevees

are 5 x 5 m (Braun-Blanquet method)

- Ground truth surveys are carried out in

next year August-September: checking

the content of al polygons and making

relevees (5 x 5 m; Braun-Blanquet

method)

- Followed by vegetation classification (of

the relevees made), preparation of digital

maps (ArcInfo/GIS) and a report.


Fieldwork, classification- For each SM, ca. 100-300 BB- relevees

are made

- Almost every polygon on the (field)map isvisited and the content (in terms of SALT-types) is determined

- The relevees are classified using adatabase with thousands of SM-releveesmade in the period 1980-present

- Bases on this relevee classification andthe polygon descriptions in the field, allpolygons get their definite content

Legendamatrix Lokaal vegetatietype: Qq0 Qq3p Qq3e Ss3

25Aa1/

25Aa2

Bedreiging: TNB TNB TNB TNB

Leg

en

daco

de v

eg

eta

tiekaart

Str

uc

tuu

rco

de

Be

dre

igin

gs

co

de

KR

W-c

od

e

Co

de

ha

bit

atr

ich

tlij

n

TM

AP

veg

eta

tieco

de

t ypenr: 1 2 3 4

Kp1 Lk TNB P 1140 Sm 100

Kp2 Lk TNB P 1140 Sm 75 10 5

Kp3 Lk TNB P 1140 Sw 10

Kp4 Lk TNB P 1310a SPq 100

Kp5 Lk TNB P 1310a SPq 95 5

Kp6 Lk TNB P 1310a Ss 40

Kp7 Lk TNB P 1310a Sm 10 15 5

Kp8 Lk TNB P 1310a Sm 5 15 5



Kp11 Lk TNB P 1310a Sm 20

Kp12 Lk TNB P 1310a Ss 20

Kp13 Lk TNB P 1310a Sm 10

Kp14 Lk TNB P 1310a Sw 5

Kp15 Hk TNB P 1320c Sm 30



25Aa1 25Aa2 24Aa2Landelijk type:


Results – Vegetation map

Distribution of SALT-

types according to the

main SM-zones (pioneer

zone, low SM, middle

and high SM)

One polygon may consist

of 1-4 SALT-types

The codes refer to the

dominant type(s)


Results – derived products

Distribution ofspecific species /indicativespecies

Centaurium littorale



Distribution ofHabitat-types(Natura 2000)



Distribution ofTMAP-types(Waddensea,TrilateralMonitoringAssessmentProgram)



Distribution of SM-zones; usedin NL as a toolfor the WFDSM-metrics(qualityaspect)

WFD metric for salt marshes

Reference conditions

All along the Dutch coast (especially in salt marsh areas)

there have been embankments, since 1000 AD

Even recently (last century): Zuiderzee, Lauwerszee,

Haringvliet were diked and these are fresh water

lakes now

This causes a.o. the effect of ‘coastal squeezing’ (sea

level rising on the one hand and seaward land

reclamation on the other, leaves little space for

natural salt marshes

Because of this enormous changes (and a lack of

historical facts on salt marshes before the

embankements) it is impossible to determine

reliable reference situations for each of the salt

marshes.

Therefore we use:

Potential Reference Status (P-REF) ~ High Status

Potential Good Ecological Status (P-GES) ~ Good

Status


metrics used

Two metrics/tools are used (see o.a. D.J. de Jong, 2007):

1. A metric for quantity (SM area)

2. A metric for quality (SM zoning)

A third one –trend- (for area and zoning) is in discussion (not used sofar)

Both metrics are separately applied for each waterbody and lead to a quality

status per tool. Final status is simply determined by combining both in one

metric: the lowest score counts

Scores within a class (P-GES, moderate, etc) are not specified/ calculated further

to a specific value in that class


metric for SM area

Based on historical data, developments in the last centuries and possibilities under presentconditions we determined the starting points for SM area in CW and TW (see upper table)

Quality status can be easily determined based on recent vegetation maps (lower tabel; for EemsDollard and Westerschelde

W ater typeP -R EF (in % o f to tal

in tertidal area)

P -GE S (in % o f to tal

in te rtidal are a)M oderate P oo r B ad

She ltered c oas ta l w ater (C W /K2) 5 3,5<25 % below

P -GE S

2 5-50% be low

P -G E S

> 50% below P -

GE S

Trans itional wate r (TW /O2) 1 0 7,5<25 % below

P -GE S

2 5-50% be low

P -G E S

> 50% below P -

GE S

W ater b od y P-R E F P-G E S M o derate P o or B ad

Eem s Dol lard (T W ) 10 % = 10 00 ha 7,5% = 700 ha<25 % belo w P -

GE S

25-50% b elow P-

G ES

> 50% be low P -

G E S

Eem s Dol lard (T W ) 740 ha

W es ters chelde (T W ) 10 % = 31 00 ha 7,5% = 230 0 ha<25 % belo w P -

GE S

25-50% b elow P-

G ES

> 50% be low P -

G E S

W es ters chelde (T W ) 239 5 ha

1 0,8 0,6 0 ,4 0,2 0


metric for SM quality (zoning)

Per waterbody 4-7 SM-zones can bedistinguished

Lack of a zone (or strongdominancy of one ormore zones) indicatesan un-balancedsituation (a disturbedsediment balance, noequilibrium betweensedimentation anderosion, one-wayvegetation developmenttowards climax stadia)



The area of each zone perwaterbody has to varybetween 5% and 35% (5zones in waterbody:pioneer, low, middle,high+Elytrigia,Brackish+Phragmites) or40% (4 zones; Brackishzone missing);

Within the climax-zonesElytrigia / Phragmitescover at most 50% ofthese zones;

Each waterbody scores 1 orzero points per zone, if theabove conditions apply



assessment of quality scores (see upper table)

Quality status can be easily determined based on recent vegetation maps (lower tabel; for EemsDollard, Westerschelde & Oosterschelde

Final score for Westerschelde: Moderate (P-GET for SM-area; Moderate for SM-quality; lowestscore counts).

As ses sm ent sc ores for m et ric S M qua lity per w aterbody

m ax score 5 M ax sco re 6 /7

P -R EF 5 7 or 6

P-G E S 4 or 3 5 or 4

M oderate 2 3 or 2

Po or 1 1

Bad 0 0

M etric SM q uality , sc ore pe r zone/c lim a x-ve getatio n and f ina l s core per w aterbody

p io ne e r low m id d leh igh

+E lym us

bra ckish

+Phra gm ites

E lym us

>5 0%

Phra gm ites

>50 %Score # cla sses

Qu ality

sta tu s

Eem s Dol lard (T W ) 1 0 0 1 1 0 1 4 7 P -GE T

W es ters chelde (TW ) 0 0 1 1 n .a. 0 n.a. 2 5 M oderate

O os tersc helde (CW ) 1 1 1 1 n .a. 0 n.a. 4 5 P -GE T

n.a. = zon e no t con sid e re d in pa rticular wa te rbo dy


Pressure gradients

Permanent stations -1or 2 per waterbody-, measuring:

1. Chemical data (nutrients, toxics, other relevant chemicals)

2. General physical-chemical parameters (Inundation regime, oxygen, salinity,transparency conditions, temperature, pH, DIP/DIN)

3. Hydromorphology (inundation regime/tidal aspects, etc)

At least over de last 10 years accurate trends of 1 - 3 are available c.q. can beestablished.

Plotting these data together with the SM-EQR (or SM-indicators) may give an idea ofthe relation between pressures (like eutrophication, hydromorhological changes)and the quality status of SM. This concerns ca. ‘general’ pressures.

More ‘specific’ pressures may be relevant for each waterbody; e.g. disturbedsediment balance in Westerschelde (because of dredging the fairway for vesselsto Antwerpen Harbour) and Oosterschelde (low tidal fluctuation because ofbarrier dam)

Need to specify what exactly is asked within WFD on pressure gradients (in relationto IC Salt Marshes) and advice to limit this to a minimum

saltmarshes and wfd - circabc research centre/jrc... · 2.1 s lp puccinellia maritima type ... kp1...

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