(Upload on September 29 2018) [ 日本語 | English ]

Wetland (湿原)

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily

Definitions (various):
  1. land where an excess of water (i.e. waterlogging) is the dominant factor determining the nature of the soil development and the types of plants and animals living at the soil surface.
  2. lands that are sometimes or always covered by shallow water or have saturated soils, and where plants adapted for life in wet conditions usually grow.

[wetlands defined by Ramsar Convention]

Five major types of wetlands (湿原型)

  • Estuarine (estuary): salt and blackish waters of coastal rivers and bays
  • Riverine (riparian): areas influenced by rivers and streams(not always categorized into wetlands) Ex. well-drained soil deposits
  • Lacustrine: lakes, reservoirs, and large ponds
  • Palustrine: marshes, bogs, swamps, and small shallow ponds (mire = bog + marsh + swamp)
  • Marine: open ocean shore line
wetland type

(Leck 1989)

Vegetation classification

  Obligate (OBL)
  Facultative wetland (FACW)  2/3 +
  Facultative (FAC)
  Facultative upland (FACU)   1/3 -
  Upland (UPL)

Type [ bog | fen | marsh | swamp | open water ] [ tussock ]
[ world | Washington (bog)| Australia (mangrove) ]

Soil: a) muck or peat, b) very dark color (=black), c) not so dark, but molted → meeting one of these requirements
Hydrology: continued saturation > 1 wk during the growing season
Environmental gradient
Four types of gradients
  • fen-bog gradient
  • hummock-follow gradient
  • marginal gradient
  • fen-carr gradient

Environmental factor: pH, DO, conductivity (important factor) + temperature, ignition loss
fen: groundwater – on the ground surface (Tokisatamappu mire)
floodplain: maintaining water system (Utonaito marsh)
production (dum, peat fuel etc.)

Bog (高層湿原)

Very acid conditions with limited woody growth, dominated by Sphagnum; conditions may be dry to plants because the peat mat prevents roots from reaching water; they root in the peat and get nutrients from rainwater. Typical associations in Washington State: Sphagnum/Vaccinium oxycoccos; Ledum groenlandicum/Sphagnum; Sphagnum-Carex spp.
Types of Bogs
Open bogs are comprised mostly of sphagnum moss and sparse sedges
Shrubby bogs support low-lying shrubs, bog cranberry, and blueberries
Treed bogs are identified by stunted black spruce with a moss and shrub understory
Benefits and Functions
• Peatlands store carbon and reduce the effects of global warming
• Help prevent downstream flooding by absorbing precipitation
• Support plants commonly used by people, including cranberries,blueberries, and Labrador tea

Topographical classification

raised bog, basin, string, continental, island, palsa, maritime, bowl, shinkhole, floating, shore, flat, polygonal, peat plateau, peat mound
Raised bog (隆起高層湿原, Regenmoore or Hochmoore in German)
≈ ombrotrophic bog
acidic, wet habitats with poor mineral salts Plants represented by peat moss +

Woody vegetation
northwestern Europe: Betula pubescens, Pinus sylvestris
sub-Alpine: Pinus mugo
northern North America: Picea mariana

threatened by peat cutting and pollution by mineral salts from the surrounding land (due to agriculture and industry)

Fen (低層湿原)

A fen is a peatland influenced by flowing surface water and/or discharged groundwater. The water moving through fens comes in contact with mineral soil creating a more nutrient rich environment than bogs. Fens vary in wetness and species diversity, with wetter fens being richer.
Types of Fens
Gramnoid fens are dominated by sedges and are usually the wettest
Shrubby fens contain stunted shrubs such as bog birch and willows interspersed with sedges and buckbean
Treed fens are much drier and contain stunted trees, especially tamarack and sometimes black spruce
Benefits and Functions
• Fens move water and nutrients through the landscape
• Sustain water levels and connectivity of wetlands across the landscape
• As peatlands, fens store carbon and reduce the effects of global warming
• Help prevent downstream flooding by absorbing precipitation, and excess water from adjacent uplands
Topographical classification
string (ストリング), seepage (浸透水性), net (網状), floating (浮島) → floating fen (根無し湿原), draw (谷地), horizontal (平坦), pond (池溏), collapse (崩落), palsa (パルサ), spring (湧水), slope (斜面) → sloping fen (斜面/傾斜地湿地)

Heath (ヒース)

shrubland dominated by ericaceous species, such as Andromeda, Bruckenthalia, Calluna, Erica, Daboecia

often developed on free-draining infertile, acidic soils
open, low-growing woody vegetation

Marsh (湿地)

Marshes are often a transition zone between open water and shorelines of lakes and river systems. They are shallow wetlands with water levels that fluctuate seasonally. Marshes receive water from precipitation, groundwater, and stream inflow.
Types of Marshes
Freshwater marshes are very productive and a variety of plants thrive on the high nutrient levels

Salt marsh (saltwater marshes) are normally associated with coastlines and fewer plants can tolerate the saline conditions
Benefits and Functions
• Plants filter and trap pollutants from the water
• Great place for wildlife viewing • Provides food and shelter for many different species of birds and mammals
• Moderates flooding and erosion by slowing down water flow
• Provide habitat for wildlife species important for trapping, such as muskrat

Shallow open water (浅瀬)

Shallow waters are distinct wetlands that represent a transition from marshes to deeper aquatic ecosystems such as lakes or rivers. They include shallow lakes and ponds, as well as wetlands found beside rivers, coastlines and shorelines. Benefits and Functions
• Provides conditions for dense submergent vegetation
• Habitat for a variety of aquatic insects and fish
• Provides food for many different birds
• Can recharge groundwater supplies

Swamp (沼沢地)

Swamps are often a transition between upland forest and other wetland types. They are normally associated with river floodplains, lakes, and ponds. Swamps are typically dominated by tall trees and shrubs, with densities greater than 60%. They can occur in either mineral or organic soil.
Types of Swamps
Thicket swamps are characterized by tall shrubs, like willow
Coniferous swamps are dominated by white or black spruce
Hardwood swamps feature balsam poplar and white birch
Benefits and Functions
• Moderate floods by slowing water flow
• Fertile soils support a diversity of trees, shrubs, and other plants
• Snags, standing dead trees, provide homes for cavity-nesting species like goldeneye, American kestrel, and northern flicker
• Recycle nutrients from decaying plant matter
• Vegetation protects shoreline areas from erosion and sedimentation

World wetland

Distribution of mires. Extent and location of global mires and peatlands (Lappalainen 1996)

A. North America 1. Canada and Alaska Tundra
Boreal forest
Hudson Bay lowlands
Complex montane, riverine, coastal systems in Alaska
Prairie potholes in Canada
2. USA East coast estuaries
Florida sawgrass marsh
Mississippi River delta
Potholes and playas
California internally drained systems
Western riparian systems
Pacific coast estuaries
B. Mexico, Central America, Caribbean 1. Mexico Main wetlands on coast
2. Caribbean Most extensive wetlands on larger islands
Islands with +1000 m mountains create rivers
Much converted to rice farming
3. Central America Complex systems on Caribbean side (70% of precip)
Mangroves on Pacific side (30% of precip)
Much conversion to shrimp mariculture
C. South America 1. Northern South America Amazon basin
Maranhao and rivers in east Brasil
Llanos of Orinoco drainage
2. Southern South America Flooded Pantanal feeds Paraguay River
Parana River runs south to join Paraguay River
Puna: Andean altiplano above 10,000
D. Europe 1. Fennoscandia, UK, N. Russia Ice and precipitation dominated systems
Palsa-, blanket-, aapa-, raised-, polygon bogs (mires)
2. Coastal shallows Wadden Sea
3. Floodplain systems Loire, Rhine, Vistula, Danube, Dnieper, Dniester, Volga
4. Mediterranean basin Mostly deltas: Rhone, Po, Nile
E. Middle East 1. Tigris and Euphrates Fed by rivers from mountains of Turkey, Iran, Afghanistan
2. Inland drainage systems like Dead Sea
3. Mangroves on coasts of Red Sea, Indian Ocean, Persian Gulf
F. Africa 1. East Africa and the Nile Basin Great Rift Valley
Lake Victoria
Valley of the Nile
Sudd floodplain
2. West and Central Africa Floodplains of the Senegal, Nile, Lake Chad; in arid Sahel
Zaire River system
Zaire and Congo Rivers; year-round flooding
3. Southern Africa Zambesi River system
Okavanga Delta (N. of the Kalahari Desert)
Etosha Pan in Angola
G. Asia 1. Northern Asia Ob-Irtysh basin
High mountains of N. Central Asia (Lake Baikal)
Tundra in the North
Internally drained seas: Caspian, Aral (eco-disaster)
2. Central and South Asia Himalayan range dominates; generates water for:
Indus, Ganges, Brahmaputra, Irrawaddy, Mekong, Yangtze, Yellow Rivers
Extensive floodplain and delta cultures
Monsoon wetlands of Bangladesh (Ganges delta)
Sundarbans (mangroves, Bengal tigers)
3. East Asia High altitude lake and bog systems, Tibetan and Mongolian plateaus
Yangtze and Yellow River floodplains
Estuarine and mangrove systems on China coast
Korea: western and southern estuaries
Japan: most remaining wetlands on Hokkaido
H. Southeast Asia 1. Equatorial Very wet, naturally forested, high diversity forests
Mangrove, swamp forest
2. Long coastline, shallow lagoons, coral reefs
I. Australia 1. Mostly flat and arid
2. Great Dividing Range along east coast Generates much hydrology; monsoons approach from east
Well-watered river valleys and estuaries to the east
Darling and Murray floodplains to the interior
3. Ephemeral internally-drained systems in interior Dry climate with widely spaced wet episodes
Salt lakes
4. Estuaries and floodplains in the tropical north
J. New Zealand & Pacific Islands 1. New Zealand: maritime climate and much rain South Island has diverse wetland landscape
Bogs, floodplains, podocarp swamp forests
North Island has estuaries
2. Pacific islands Mostly small islands with salt or brackish systems Lagoons, mangroves, brackish lakes
Larger islands with mountains create river systems
Freshwater lakes form in volcanic calderas


China Fig. 1. Peat distribution in China (中国の泥炭分布)
I: Peat distribution region of north-eastern mountain land, hills and depressions
II: Peat distribution region of the mountain plateaus and valley basins in Omg-zang plateau
III: Peat distribution region of north-western lofty mountains and peadmonts
IV: Buried peat distribution region of eastern deposit plateau
V: The buried peat distribution region of low mountains, hills and coast in the middle and southern parts of China
VI: The buried peat distribution region of south-western mountain plateaus and basins
Table 2. The area of peatlands and amount of peat deposit in the respective regions I to VI. The values are determined by references and field measurements. The area is defined as peat > 0.3 m in depth. The amount is expressed by dry weight.
Region Area (× 10M4 ha)            Amount (× 109 ton)
       ---------------------------- --------------------------
       Suface-   Deposited-  Total  Surface- Deposited-  Total
       peatland  peatland           peatland peatland

  I      214.0      3.1      217.1   153.2      2.5      155.7
  II      94.0      -         94.0    51.0      -         51.0
  III     36.0      1.5       37.5    11.3      0.5       11.8
  IV       0.9     38.0       38.9     0.5     29.8       30.3
  V        0.7      9.2        9.9     0.3      6.5        6.8
  VI       2.1     16.4       18.5     1.2     13.4       14.6
  Total  347.7     68.2      415.9   217.5     52.7      270.2

wetland research in China (中国での湿原研究)

Table 3. Main ecological properties of mires in China.

Ecological propertiesMicrotopography
(grassy marshland)
Hydrologic conditionPlant communityPeat layer
Types of peatmireFormHeight (m)Desnity (%)Phreatic surface (m)Water-logged depth (m)Thickness (m)Water content (%)pH
Permanently water-
logged peatmire in depression
Floating blanket---0.1-0.4Carex lasiocarpa
Menyanthes triflora
Glyceria aquatica
Utricularia vulgaris
3-6> 907.0-7.5
Seasonally water-
logged peatmire in scattered hills
Ridge0.3-0.65-150.0.-0.050.05-0.1Carex muliensis
Equisetum heleocharis
Helecharis sp.
Seasonally water-
logged peatmire on hills
> 50
< 0.10.05-0.15Carex spp.
Kobresia tibetica
Kobresia spp.
Temporarily water-
logged peatmire in scattered hills
Lump0.2-0.310-300.1-0.40.0-0.1Kobresia spp.
Carex spp.
0.3-1< 707.0
Table 1. Analysis of the physical and chemical properties of partial samples of peat in China
TypeTypes of peatDecompo-
sition (%)
Total C (%)Organic matter (%)Raw ash (%)HCl-soluble matter (%)Total N (%)P2O5 (%)K2O (%)CaO (%)Fe2O3 (%)Total humic acid (%)ph (H2O)
Low-moor peatCarex25.842.372.921.
Aniphyllum fortunei-Carex24.242,072.527.
High-moor peatLedum palustre-moss peat17.551.488.711.
Moss peat16.150.887.512.,2
Carex moss peat19.240.770.
Medium-moor peatLarix-Carex moss peat18.335.771.

Chinese wetland vegetation

Washington State, USA

Wetland vegetation

The US Fish & Wildlife Service has a comprehensive classification system useful for wetlands.

Coastal vegetation

The environment of coastal estuaries (Estuarine system), including river deltas, and bays is dominated by tidal fluctuations. This factor and its correlates, such as fluctuating salinity,poor aeration, wave action, and twice daily cycles of submergence and exposure, produce vegetation types characterized by relatively few species. Coastal marshes are highly productive.
Low intertidal to subtidal muds, dominated by Zostera marina. Typical association: Zostera marina
Low salt marsh:
Higher intertidal, usually with some fresh water influence, especially in river deltas. Inundated nearly every day. Typical associations: Scirpus maritimum; Carex lyngbey; Calydistichlis spicata; Jaumea carnosa-Disp; Disp-Salicornia virginica; Savi.
High salt marsh:
Upper marshes, where daily inundation is less than a daily occurrence. Typical associations: Agrostis alba-Festuca rubra; Agal-Carex lyngbyei; Caly-Distichlis spicata; Disp-Salicornia virginica; Potentilla pacifica-graminoids.

Table. Common species in a vertical gradient.

    Species               Eelgrass   Low marsh   High marsh

    Zostera marina            X
    Salicornia virginica      t          X            x
    Triglochin maritimum      t          X            x
    Carex lyngbeyi                       X            x
    Jaumea carnosa                       X            x
    Spergularia marina                   X            x
    Scirpus americanus                   X            x
    Cotula coronopifolia                 X            x
    Cuscuta salina                       X            t
    Spartina alterniflora                X            t
    Atriplex patula                      x            X
    Plantago maritima                    x            X
    Distichlis spicata                   x            X
    Scirpus maritimum                    t            X
    Deschampsia caespitosa                            X
    Hordeum brachyanthermum                           X
    Grindelia integrifolia                            X
    Potentilla pacifica                               X
    Trifolium wormskjoldii                            X
    Agrostis alba                                     X
    Festuca rubura                                    X

Inland wetland vegetation is generally associated with rivers (riparian), lakes (lacustrine), or other wetlands not directly influenced by lakes or rivers (palustrine). Riverine vegetation is usually unstable and dominated by elements of the forested wetlands described below.

Freshwater marsh

Usually associated with lakes (lacustine), or areas of limited drainage (palustrine).
Typical Lacustrine Associations: Deep: Nuphar-Nymphaea; Scirpus acutus; Shallow: Typha latifolia; Phalaris arundinacea; Phragmites communis; Tyla-Lythrum salicaria; Carex obnupta (plus various graminoids-dominated associations); Phar-Iris pseudacorus; Tyla-Scirpus microcarpus.

                        Deep marsh           Emergent

Eleocharis spp.                              Emergent
Epilobium angustifolium                      Emergent
Iris pseudacorus        Emergent
Lemma minor             Floating
Lythrum salicaria                            Emergent (intro)
Myriophyllum spicatum   Submerged (intro)
Nuphar polysepalum      Floating fixed(intro)
Nymphaea odorata        Floating fixed(intro)
Oenanthe sarmentosum                         Emergent
Phalaris arundinacea                         Emergent
Phragmites communis                          Emergent
Polygonum spp.          Submerged            Submerged-
Scirpus microcarpus                          Emergent
Typha latifolia                              Emergent

Palustrine systems are nontidal wetlands dominated by woody vegetation or persistent emergents. They include marshes, swamps, ponds (not lakes) and bogs. They can be located shoreward of lakes and rivers, on flood plains, or in isolated catchment basins.

Foster's Island

The trail starts behind the MOHAI and traverses through several wetland associations. Characterize each association, based on the US Fish and Wildlife system (e.g., palustrine forested wetland).
Species (common name), description Carex aquatilis (water sedge), leaves w/3-ranked sheaths
Eleocharis spp. (spike-rush), solitary, term. spike; emergent
Equisetum spp. (horsetail)
Iris pseudocorus (yellow marsh iris), yellow flowers; emergent
Juncus balticus (baltic rush), diffuse inflorescence
Juncus effusus (common rush), stem round; many flowers, lateral, dense inflorescence
Lemna minor (duckweed), floating aquatic
Lythrum salicaria (purple loosestrife), red flowers, leaves like fireweed; emergent
Myriophyllum spicatum (watermilfoil), feathery leaves; submerged aquatic
Nuphar polysepalum (Indian pondlily), sepals = 9; flowers yellows
Nymphaea odorata (American waterlily), sepals = 4; flowers white/pink
Oenanthe sarmentosa (water parsley), dissected leaves
Phalaris arundinacea (reed canarygrass), congested panicle; large ligules; emergent
Potentilla pacifica (Pacific silverweed), pinnately compound leaf
Rumex crispus (curly dock weed)
Scripus microcarpus (small-fruited bulrush), many large, terminal spikelets; emergent
Scripus pallidus (pale bulrush), few large, lateral spikelets
Typha latifolia (cattail), emergent
Alnus rubra (red alder), leaves with revolute margins
Betula sp. (birch), white bark
Cornus stolonifera (red-osier dogwood), red stem; cottony veins when pulled apart
Populus trichocarpa (black cottonwood), large deltoid leaves
Rhamnus purshiana (cascara), rhomboid leaf; thick veins
Salix lasiandra (Pacific willow), narrow leaf, large round stipules, glands
Salix hookeriana (Hooker's willow), broad, rounded leaf
Salix scouleriana (Scouler's willow), butterfly stipules, broadleaf, leaves reddish beneath
Spiraea douglasii (steeplebush), hardback cylindric rose-colored inflorescence


Wet meadow

Associated with lakes (lacustine) or wet depressions and bogs (palustrine). Several species from shallow marsh, plus various grasses, sedges, and rushes. Often border on persistent emergent wetlands.

Scrub-shrub palustrine wetlands

Associated with seasonally or permanently flooded low-lying terrain, usually part of a stream drainage or swamp system. It differs from forested wetlands in being dominated by shrub species or by young tree species, especially alder. Typical associations in Washington State: Spiraea douglasii; Acer circinatum/Athyrium filix-femina; Cornus stolonifera-Acci; Alnus rubra-Salix spp.; Rhamnus purshiana-Salix spp.; Salix spp.; Rubus spectabilis (seral); Rubus discolor (seral).

Forested wetland

Associated with seasonally or permanently flooded terrain, sometimes riparian or lacustrine, but often simply in poorly drained areas. Typical associations in Washington State: Fraxinus oregana/Athyrium filix-femina; Thujaplicata/ Lysichitum americanum; Alnus rubra/Acer circinatum; Populus trichocarpa-Acer macrophyllum; Populus tremuloides/Salix spp.

Table. Representative species on bog
  Species                  Wet      Scrub-  Forested   Bog
                           meadow   shurb   wetland

  Juncus effusus            x
  Lysichitum americanum     x        x                  x
  Scirpus microcarpus       x
  Eleocharis spp.           x
  Equisetum spp.            x        x
  Phalaris arundinacea      x        x
  Ranunculus repens         x
  Spiraea densiflora                 x        x
  Salix spp.                         x        x
  Malus fusca                        x
  Acer circinatum                    x        x
  Cornus stolonifera                 x
  Rhamnus purshiana                  x
  Oenanthe sarmentosa                x
  Veronica scutellata                x
  Populus trichocarpa                x        x
  Alnus rubra                        x        x
  Acer macrophyllum                           x
  Fraxinus oregana                            x
  Thuja plicata                               x         x
  Rubus spectabilis                  x        x
  Sambucus racemosa                           x
  Oplopanax horridum                                    x
  Ledum groenlandicum                x                  x
  Kalmia occidentalis                x                  x
  Sphagnum spp.                                         x
  Athyrium filix-femina                       x         x
  Drosera rotundifolia                                  x
  Vaccinium oxycoccos                                   x
  Nuphar polysepalum                                    x
  Carex spp.                         x        x         x
  Juncus spp.                                           x
  Menyanthes trifoliata                                 x


Mangrove is one of the saltwater (s.l.) biomes (バイオーム) with rich fauna. Mangrove forests replace salt marsh in tropical and subtropical regions.


total area = ca 1500 km²
mangals (mangrove swamp and/or forest) mainly distributed on the northern and eastern coast → Western Australia (西オーストラリア)
in Bunbury, Western Australia, at February 7 2004 → algae (海藻)

Tussock (谷地坊主)

Tussock (谷地坊主) called in plant ecology

A clump or tuft, as of growing grass or sedge

→ earth hummock (十勝坊主)

Tussocks seen in the world

Tussock1 Tussock2 Tussock3 Tussock4

New Zealand

[1] Close-up showing a single tussock in decayed stage. [2] A conony of tussocks. You may be able to see 'facititative effects' of tussocks on cohabitants'. [1/2] On the mountainside of Mount Ruapehu, New Zealand, on December 17, 1996. In Tongariro National Park, a few types of tussocks were classified: Chionochloa rubra Zotov [Poaceae] = red tussock, Festuca novae-zelandiae [Syn. Festuca ovina var. novae-zelandiae] (and Festuca matthewsii) = hard tussock (and silver tussock), and Rytidosperma setifolium = bristle tussock.


[3] Carex oxyandra on Mount Usu. [4] Carex middendorffii on a post-mined Sarobtetsu mire (Koyama & Tsuyuzaki 2010). The tussocks facilitate the establishment of seedling by altering microhabitats (Koyama & Tsuyuzaki 2012). However, the facilitative effects were eliminated when the climate was unusual (Koyama & Tsuyuzaki 2013). [5] tussock formed by Festuca rubra. Basically this species establishes on dry sites.



[6] a Eriophorum vaginatum tussock on Poker Flat after the 2004 wildfire. The tussock suvivied through the fire and vegetatively reproduced (Tsuyuzaki et al. 2013).


Carex meyeriana tussock increased species richness on the top (Tsuyuzaki & Tsujii 1992).