Apologies for top-posting, but the interface in the browser does not enable me to make any sense of multiple comments. Anyway here goes: Zostera (eel-grass) grows below the tide line, so really is not an emergent plant. Other things in your list of aquatic bed vegetation are also not usually apparent on the surface (e.g., Chara). Some such as Kelp will be visible at the lowest tides. I don't think any of these sensibly qualify for the current natural=wetland tag, which implicitly connotes emergent vegetation typically on a land surface which can dry out. Some emergent vegetation will have it's foot in the water, but water depth will be shallow (typical Phragmites beds). I'd suggest considering a new tag for submerged vegetation in marine environments. At this point I'm not sure about freshwater vegetation which is totally submerged (but see below). For the detailed US classification of wetlands, this is what the plant_community tag is there for: more detailed, more scientifically precise categories. Obviously many of these are not easy for the average mapper to identify, but when information is available it is often a good way of enhancing the base tagging. I think there is also a US National Vegetation Classification. I've documented some parts of the UK equivalent, including one of the types of Alder Carr (equivalent to your Alder meadow). Phragmites does grow in estuarine environments, with brackish water. I learnt some years ago that German usage of reedbed (Rohr) includes other tall emergent plants: notably sedges (Carex), Cladium, reed-mace/cat's-tails (Typha), cane (Arundo) and club-rushes. PresumabThus the meaning of wetland=reedbed may well be wider than expected in some countries. One way to be sure is to add a dominant_taxon tag (e.g., Phragmites australis, Carex, Typha etc). As for floating water plants (which I would not particularly class as emergent, including water-lilies) they can have odd life cycles. Some living on the bed of the water body when dormant and later floating during the growth season (Water Soldier & Frogbit). There are certainly places in France where a carpet of Duckweed coats the waterways during the summer. Unlike Kelp & Eelgrass beds (one a significant carbon sink, the other increasingly threatened) I've never felt the need to map such things (they are seasonal, and usually quite small features). Even something like Water Hyacinth which does form large patches is likely to change because of control measures. Jerry
In Wednesday, 18 December 2019, 22:25:50 GMT, Kevin Kenny <kevin.b.ke...@gmail.com> wrote: On Wed, Dec 18, 2019 at 2:08 PM Clifford Snow <cliff...@snowandsnow.us> wrote: > > How should eelgrass[1] be tagged? I see that wetland=reedbed [2] has been > used in tidal areas mainly in Europe but also in the US but they are two > different plants. Perhaps wetland_class=emergent or wetland_class=aquatic_bed? (How does the eelgrass grow in the area you're considering?) Thus saith 'Classification of Wetlands and Deepwater Habitats of the United States' (https://www.fws.gov/wetlands/documents/classwet/index.html): https://www.fws.gov/wetlands/documents/classwet/emergent.htm : Definition. The Emergent Wetland Class is characterized by erect, rooted, herbaceous hydrophytes, excluding mosses and lichens. This vegetation is present for most of the growing season in most years. These wetlands are usually dominated by perennial plants. All water regimes are included except subtidal and irregularly exposed. https://www.fws.gov/wetlands/documents/classwet/aquatic.htm Definition. The Class Aquatic Bed includes wetlands and deepwater habitats dominated by plants that grow principally on or below the surface of the water for most of the growing season in most years. Water regimes include subtidal, irregularly exposed, regularly flooded, permanently flooded, intermittently exposed, semipermanently flooded, and seasonally flooded. Aquatic beds further divide into algal (e.g., kelp, rockweed, stoneword), moss (e.g. Fisseidens, Fontinalis), rooted vascular (Zostera would fall in this category), and floating vascular (duckweed, water lettuce, water hyacinth, water-nut (Trapa), water fern (Salvinia), bladderwort, and so on). Rooted vascular aquatic beds occur in marine, estuarine, riverine, lacustrine and palustrine systems Some species, such as the water lily Nuphar luteum, are hard to classify between 'aquatic bed' and 'emergent', since it usually grows as lily pads, but occasionally stands erect above the water surface. Some of the eelgrasses have the same difficulty in classifying. The categories are always going to be fuzzy around the edges. USFWS would therefore label your eelgrass bed - if I understand correctly what you're trying to label - as "Marine, subtidal, aquatic bed, rooted vascular" while a typical reedbed might be "palustrine, emergent wetland, persistent, dominant vegetation Phragmites spp." and a typical alder meadow near me could be "palustrine, scrub-shrub wetland, broad-leaved deciduous, predominant plant Alnus spp." I have Absolutely No Idea how to fit a classification scheme like Cowardin's into a 'folksonomy' like OSM's. -- 73 de ke9tv/2, Kevin _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
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