STRP task 49: Ramsar and wetland classifications – vegetational and hydrogeomorphic

This note for STRP WG1consideration at STRP14 is in relation to it’s 2006-2008 task concerning developing a simple hydro-geomorphic classification system for wetlands, in relation to ecological character description and designation of Ramsar sites, and provides the various schemas which have to date been adopted or considered for recommendation.

I am prefacing this with some comments from Dave Pritchard received following a brief recent dialogue with and question from Heather MacKay about the need to progress and pin town solution to delivery of this task.

Nick Davidson17 January 2008

Dave wrote:

“Both the "wetland type classification" issue and the "biogeographic regionalisation" issue have had a bumpy ride at times in recent years, and we seem to have had more difficulty than expected in getting closure on the tasks.  It's my belief that the reasons for this have nothing to do with multiplicity of approaches, but (once again) are more to do with the definition of purposes.  At some point (as we've been progressively doing with things like wetland inventory, national reporting etc) it might be nice to develop a simple but more explicit articulation of the uses to which the Ramsar classification system are put and its reason for needing to exist - for example:  - to provide contextual dimensions of describing the ecological character of any individual wetland; - to provide the basis for a "representativity of types" objective in the site network; - to enable various analysis and assessment questions (extent, trends, signficance etc). Something along these lines would show why it matters to take any particular approach, or whether (in the case of biogeographic regions) several approaches could all be valid, provided the choice and rationale is made explicit in a given case.  That way it would be seen more properly as a means to a defined end rather than a search for some academic absolute "truth". [Thus at STRP14 if we could get] agreement on a crisp definition of "what we need classification for" might offer a useful step forward.  What I think would then become clear is that the middle purpose of the three above is the main one for which there are officially adopted decisions to date.  The question about what is the best approach to take to classification systems then (for me) becomes less to do with what is the most logical or elegant way of subdividing a description of the world's wetland wealth; and more to do with what are the axes of variety that we want represented in the Ramsar List.  (And maybe in fact we want a biological-diversity axis AND a hydrogeographical-functions axis AND an ecosystem services axis).  Getting clarity on this latter question would be the fundamental thing to do.” [end of quote]

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Additional comment from the DSG: The other aspect of considering such classifications is to avoid getting too caught up in the detail, particularly in relation to handling such things as multi-scalar issues etc. For consistent application by Ramsar Parties worldwide, we as a starter need one or more simple, ‘top-level’ schema(s) for purpose(s); one can then point at a multiplicity of different sets of modifiers of increasing complexity if for purpose someone needs to go into that level of detail.

There are also some interesting approaches embodied in the Australia ecological character description approaches which speak to aspects of this, particularly in the use of simple pictorial conceptual models, which identify the key hydro-geomorphic and biological features and processes. Other similar in concept conceptual models are in the Ramsar COP9 groundwater guidelines – see below. An example of an application for a single wetlands of the Australian approach is about to be published, and will be posted for STRP14’s ecological character considerations as a separate document.

The schemas provided below are:

A. Ramsar Classification System for Wetland Type

B. Tabulations of Wetland Type characteristics – from RIS guidance notes

C. Hydro-geomorphic classification (adopted as Annex 2 in Resolution IX.1 Annex C ii) Guidelines for the management of groundwater to maintain wetland ecological character)

D. Application of ‘groundwater’ hydro-geomorphic classification (C. above) for water quality characteristics. (from Verhoven et al. draft Water quality and wetlands report to STRP. 2007)

E. Draft classification systems developed for STRP in 2003-2005 triennium by Christine & Vic Semeniuk (discussed at mid-term workshops 2004, but not subsequently progressed)

A. Ramsar Classification System for Wetland Type[Note: The classification is more of a typology, based largely, but not wholly, on habitat characteristics (and vegetation type - or the absence of it)]

The codes are based upon the Ramsar Classification System for Wetland Type as approved by Recommendation 4.7 and amended by Resolutions VI.5 and VII.11 of the Conference of the Contracting Parties. The categories listed herein are intended to provide only a very broad framework to aid rapid identification of the main wetland habitats represented at each site.

To assist in identification of the correct Wetland Types to list in section 19 of the RIS, the Secretariat has provided below tabulations for Marine/Coastal Wetlands and Inland Wetlands of some of the characteristics of each Wetland Type.

Marine/Coastal Wetlands

A -- Permanent shallow marine waters in most cases less than six metres deep at low tide; includes sea bays and straits.

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B -- Marine subtidal aquatic beds; includes kelp beds, sea-grass beds, tropical marine meadows.

C -- Coral reefs.D -- Rocky marine shores; includes rocky offshore islands, sea cliffs.E -- Sand, shingle or pebble shores; includes sand bars, spits and sandy islets;

includes dune systems and humid dune slacks.F -- Estuarine waters; permanent water of estuaries and estuarine systems of

deltas.G -- Intertidal mud, sand or salt flats.H -- Intertidal marshes; includes salt marshes, salt meadows, saltings, raised salt

marshes; includes tidal brackish and freshwater marshes.I -- Intertidal forested wetlands; includes mangrove swamps, nipah swamps

and tidal freshwater swamp forests. J -- Coastal brackish/saline lagoons; brackish to saline lagoons with at least one

relatively narrow connection to the sea.K -- Coastal freshwater lagoons; includes freshwater delta lagoons.Zk(a) – Karst and other subterranean hydrological systems, marine/coastal

Inland Wetlands

L -- Permanent inland deltas.M -- Permanent rivers/streams/creeks; includes waterfalls.N -- Seasonal/intermittent/irregular rivers/streams/creeks.O -- Permanent freshwater lakes (over 8 ha); includes large oxbow lakes.P -- Seasonal/intermittent freshwater lakes (over 8 ha); includes floodplain

lakes.Q -- Permanent saline/brackish/alkaline lakes.R -- Seasonal/intermittent saline/brackish/alkaline lakes and flats.Sp -- Permanent saline/brackish/alkaline marshes/pools.Ss -- Seasonal/intermittent saline/brackish/alkaline marshes/pools. Tp -- Permanent freshwater marshes/pools; ponds (below 8 ha), marshes and

swamps on inorganic soils; with emergent vegetation water-logged for at least most of the growing season.

Ts -- Seasonal/intermittent freshwater marshes/pools on inorganic soils; includes sloughs, potholes, seasonally flooded meadows, sedge marshes.

U -- Non-forested peatlands; includes shrub or open bogs, swamps, fens.Va -- Alpine wetlands; includes alpine meadows, temporary waters from snowmelt.Vt -- Tundra wetlands; includes tundra pools, temporary waters from snowmelt.W -- Shrub-dominated wetlands; shrub swamps, shrub-dominated freshwater

marshes, shrub carr, alder thicket on inorganic soils.Xf -- Freshwater, tree-dominated wetlands; includes freshwater swamp forests,

seasonally flooded forests, wooded swamps on inorganic soils.Xp -- Forested peatlands; peatswamp forests.Y -- Freshwater springs; oases. Zg -- Geothermal wetlandsZk(b) – Karst and other subterranean hydrological systems, inland

Note: “floodplain” is a broad term used to refer to one or more wetland types, which may include examples from the R, Ss, Ts, W, Xf, Xp, or other wetland types. Some examples of floodplain wetlands are seasonally inundated grassland (including natural wet meadows), shrublands, woodlands and forests. Floodplain wetlands are not listed as a specific wetland type herein.

Human-made wetlands

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1 -- Aquaculture (e.g., fish/shrimp) ponds2 -- Ponds; includes farm ponds, stock ponds, small tanks; (generally below 8 ha).3 -- Irrigated land; includes irrigation channels and rice fields.4 -- Seasonally flooded agricultural land (including intensively managed or

grazed wet meadow or pasture).5 -- Salt exploitation sites; salt pans, salines, etc.6 -- Water storage areas; reservoirs/barrages/dams/impoundments (generally

over 8 ha).7 -- Excavations; gravel/brick/clay pits; borrow pits, mining pools.8 -- Wastewater treatment areas; sewage farms, settling ponds, oxidation

basins, etc.9 -- Canals and drainage channels, ditches.Zk(c) – Karst and other subterranean hydrological systems, human-made

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B. Tabulations of Wetland Type characteristics – from RIS guidance notes

Note. These tabulations were developed by the Secretariat during 2002-2005 triennium and included in the additional guidelines and explanatory notes for filling the RIS, post-COP9. Their aim is to provide some simple ‘decision-trees’ to help a Party preparing an RIS to identify correctly which Ramsar Wetland Types they have within their wetlands.

Marine / Coastal Wetlands:

Saline water

Permanent

< 6 m deep AUnderwater vegetation B

Coral reefs C

ShoresRocky DSand, shingle or pebble E

Saline or brackish water

Intertidal

Flats (mud, sand or salt) G

Marshes HForested I

Lagoons JEstuarine waters F

Saline, brackish or fresh water

Subterranean Zk(a)

Fresh water Lagoons K

Inland Wetlands:Fresh water

Flowing waterPermanent

Rivers, streams, creeks

M

Deltas LSprings, oases Y

Seasonal/intermittent

Rivers, streams, creeks

N

Lakes and pools

Permanent > 8 ha O< 8 ha Tp

Seasonal/intermittent > 8 ha P

< 8 ha TsMarshes on inorganic soils Permanent Herb-

dominatedTp

Permanent/ Seasonal/intermittent

Shrub-dominated WTree-dominated

Xf

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Seasonal/intermittent

Herb-dominated

Ts

Marshes on peat soils Permanent Non-forested U

Forested XpMarshes on inorganic or peat soils

High altitude (alpine) VaTundra Vt

Saline, brackish or alkaline water

Lakes Permanent QSeasonal/intermittent R

Marshes & pools

Permanent SpSeasonal/intermittent Ss

Fresh, saline, brackish or alkaline water

Geothermal ZgSubterranean Zk(b)

Note. A similar schema has not yet been developed for human-made wetlands types.

C. Hydro-geomorphic classification (adopted as Annex 2 in Resolution IX.1 Annex C ii) Guidelines for the management of

groundwater to maintain wetland ecological character)[Note. This annex provided a simple hydrological wetland typology, as the basis for then identifying a range of hydrological subtypes. The Annex also provides simple two-dimensional ‘conceptual models’ for each of these types and subtypes.]

Linking landscape location and water transfer mechanisms

The hydrological wetland typology used in these guidelines is based on landscape location and water transfer mechanisms. Landscape location produces seven types within the Ramsar definition of wetlands (Figure A2.1). These can be further subdivided on the basis of dominant water transfer mechanisms to produce 15 subtypes (Table A2.1). In particular, the subtypes are based on whether the likely dominant water transfer mechanism in each type is surface water or groundwater or a combination of the two. Figure A2.2 to A2.7 show diagrams of some example hypothetical wetlands in each subtype. For wetlands in topographically flat areas, only the surface water subtype is relevant.

Clearly, the subtype may not be known at the outset of the study, as the contribution of groundwater to the wetland is difficult to determine. However, the typology can be used to guide understanding of hydrological mechanisms that can be tested by data.

Table A2.1 Wetland landscape location types and hydrological subtypes

Landscape location Subtype based on water transfer mechanism

Flat upland wetlands Upland surface water fedSlope wetlands Surface water-fed

Surface and groundwater-fedGroundwater-fed

Valley bottom wetlands Surface water-fedSurface and groundwater-fedGroundwater-fed

Underground wetlands Groundwater-fedDepression wetlands Surface water-fed

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Surface and groundwater-fedGroundwater-fed

Flat lowland wetlands Lowland surface water fedCoastal wetlands Surface water-fed

Surface and groundwater-fedGroundwater-fed

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Figure A2.1. Landscape locations of wetlands [Note. It is intended to include boxes with suitable photographs of each type]

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Upland flat area wetlandsSurface water-fed: Wetland underlain by impermeable strata.Input dominated by precipitation. Output by evaporation and surface outflow. Example: upland blanket bogs

Lowland flat area wetlandsSurface water-fed: Wetland underlain by impermeable strata.Input dominated by precipitation. Output by evaporation and surface outflow. Example: rain-fed domed mires.

Figure A2.2. Flat area wetlands (see Annex 1 for key to abbreviations)

Slope wetlandsSurface water-fed: Wetland underlain by impermeable strata. Input dominated by precipitation, surface runoff and possible spring flow. Output by evaporation and surface outflowSlope wetlandsSurface and groundwater-fed: Wetland separated from underlying aquifer by lower permeability layer. Input from groundwater seepage, precipitation and surface runoff. Groundwater input may be restricted by lower permeability layer. Output by evaporation and surface outflow. Example:

Slope wetlandsGroundwater-fed: Wetland in direct contact with underlying aquifer. Input dominated by groundwater seepage, supplemented by precipitation and surface runoff. Output by evaporation and surface

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outflow. Example:

Figure A2.3. Slope wetlands

Depression wetlandsSurface water-fed: Wetland underlain by impermeable strata. Input dominated by precipitation, surface runoff and possible spring flow. Output by evaporation only. Example:

Depression wetlandsSurface and groundwater-fed: Wetland separated from underlying aquifer by lower permeability layer. Input from groundwater discharge, when groundwater table is high, precipitation, surface runoff and possibly spring flow. Groundwater input may be restricted by lower permeability layer. Output by evaporation and groundwater recharge when groundwater table low. Example:

Depression wetlandsGroundwater-fed: Wetland in direct contact with underlying aquifer. Input dominated by groundwater discharge when groundwater table is high, supplemented by precipitation, surface runoff and spring flow. Output by evaporation and groundwater recharge when groundwater table low.

Figure A2.4. Depression wetlands

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Valley bottom wetlandSurface water-fed: Wetland underlain by impermeable strata. Input dominated by over-bank flow and lateral flow, supplemented by precipitation and surface runoff. Output by drainage, surface outflow and evaporation. Inflows and outflows are controlled largely by water level in the river or lake. Example: alluvial floodplains

Valley bottom wetlandSurface and groundwater-fed: Wetland separated from underlying aquifer by lower permeability layer. Input from over-bank flow and groundwater discharge, supplemented by runoff and precipitation. Groundwater flow may be restricted by intervening low permeability layer. Output by drainage, surface outflow, evaporation and groundwater recharge. Example: floodplains on sandy substrate

Valley bottom wetlandGroundwater-fed: Wetland in direct contact with underlying aquifer. Input dominated by over-bank flow and groundwater discharge, when groundwater table is high, supplemented by runoff and precipitation. Output by groundwater recharge when water table is low, drainage, surface outflow and evaporation. Example: floodplains in karst systems

Figure A2.5. Valley bottom wetlands

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Coastal wetlandsSurface water-fed: Wetland underlain by impermeable strata. Input dominated by tidal flow, precipitation, surface runoff and possible spring flow. Output by evaporation and surface outflow

Coastal wetlandsSurface and groundwater-fed: Wetland separated from underlying aquifer by lower permeability layer. Input from tidal flow, groundwater seepage, precipitation and surface runoff. Groundwater input may be restricted by lower permeability layer. Output by evaporation and surface outflow. Example:

Coastal wetlandsGroundwater-fed: Wetland in direct contact with underlying aquifer. Input dominated by groundwater seepage and tidal flow, supplemented by precipitation and surface runoff. Output by evaporation and surface outflow. Example:

Figure A2.6. Coastal wetlands

Underground wetlandsGroundwater-fed: Wetlands formed with solution caves in permeable rocks. Input dominated by spring flow and groundwater discharge. Output by groundwater recharge. Example:

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Figure A2.7. Underground wetlands

D. Application of ‘groundwater’ hydro-geomorphic classification (C. above) for water quality characteristics. (from Verhoven et al. draft Water quality and wetlands report to STRP. 2007)This approach provides an example of how the simple approach in C. above could have added to it various different sets of ‘modifiers’ for more specific purposes, in this case water quality characteristics.

E. Draft classification systems developed for STRP in 2003-2005 triennium by Christine & Vic Semeniuk (discussed at mid-

term workshops 2004, but not subsequently progressed)This very detailed and complex paper “Classification of natural inland, coastal, andanthropogenic wetlands - a proposal to the Ramsar Bureau for global application” includes proposals for three sets of hydro-geomorphic based classifications, for:

i. A hierarchical/scalar classification for natural inland wetlands;ii. A classification for open coastal, embayed coastal, deltaic and estuarine

Wetlands; andiii. A classification for artificial, alienated, modified, and managed

anthropogenic wetlands.

The full draft text is posted in the STRP Support Service Library of WG1 inventory and assessment.

Below are some of the tabulations provided in the proposed hierarchical/scalar classification for i. natural inland wetlands and ii. coastal (intertidal) wetlands.

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i. Natural inland wetlands

Use of scale to define size of site-specific individual wetlands:

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Scalar approach to delineate aggregations of wetlands and their patterning:

The proposed classification: at the site specific scale:

Combining these in a matrix structure results in various categories of wetlands defined on landscape type and water regime (or hydroperiod). Some of the categories are axiomatically not possible (e.g., permanently inundated hill-tops, or slopes), and so focusing on actual wet terrain that is realistic, there are 19 primary categories of wetlands, as follows:

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Self-emergent wetlands:

Descriptors of landscape:

Descriptors of water:

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Descriptors of vegetation:The nine terms [Figure 5.11] generated by the classification scheme can be used as descriptors to characterise a wetland vegetationally at the organisational level:

The proposed classification: at the scale of naturally occurring groups -consanguineous suites:

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5.10 The proposed classification: at the largest scale of subregions and regions:A wetland region is usually a few to several hundreds of kilometres across, and has geological, physiographic, climatic and set of hydrological attributes that separate it from adjoining regions. As a consequence of these characteristics, a distinct groups of wetlands are developed. Essentially there are repetitions of the consanguineous suites described above occurring with the subregion or region.

ii. coastal (intertidal) wetlands[Note. This classification covers effectively only intertidal coastal wetlands, and so does not address coverage of the full scope of the Ramsar definition of coastal/nearshore marine systems. DSG]

The diverse settings, determinative environments and expressions of coastal wetlands which contribute to the complexity observed in coastal zones include:

• climate setting (tropical, temperate, boreal and arctic; and arid versus humid)• oceanographic setting (macrotidal, mesotidal, microtidal, high wave energy, low wave energy)• position within the tidal zone (low, mid, high tidal surfaces)• morphology of the surface (flats, slopes, fans, creeks, spits/cheniers, beaches)• substrate texture type (gravel, sand mud, rocky shores, bouldery shores, rock pavements)• substrate composition (siliciclastic grains, carbonate grains, carbonate mud, gypsum)• biogenic influence (e.g., bioherms, biostromes, tidal forests, tidal seagrass)

Approach to classification of coastal`wetlandsThe use of scale as a framework is strongly recommended. Classification of coastal landscape proposed here incorporates three scales:

large scale, or megascale (e.g., where rivers enter the sea, estuaries or deltas are developed, depending on extent of sedimentation to fill the valley tract); within this scale there are smaller scale units of mesoscale and microscale;

medium scale, or mesoscale, where coastal wetland units present themselves as relatively simple units such as beaches, tidal flats, and rocky shores;

small scale, or microscale, in which the wide diversity of form, substrates, biota, and salinity, developed in response to coastal gradients and coastal process, are evident.

Megascale involves scales of observation at > 10 km x 10 km to 1 km x 1 km; mesoscaleinvolves scales of observation at < 1 km x 1 km to 100 m x 100 m; fine scale involves scalesof observation at < 100 m x 100 km.

Megascale coastal settingFour types of megascale coastal systems are recognised, as related to the interaction between the marine environment and riverine input. Applied as adjective descriptors, these are:

1. open coastal2. embayed coastal3. estuarine

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4. deltaic

These can be grouped into those wholly marine or those mixed marine an riverine.

The mesoscale coastal wetlandsWithin the megascale coastal units, a diverse range of mesoscale coastal wetlands may be developed. The mesoscale units include the following:

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The microscale coastal wetlands: subdivision of mesoscale

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Descriptors of finer scale coastal units

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