[Talk-GB] Typical plants and features of grassland, heath, scrub and woodland in Britain

[Tom Crocker]

Thank you all for your fantastically helpful replies. I'll try to digest
them fully before responding further.

Happy mapping

Tom

On Thu, 16 Sep 2021, 13:05 SK53, <sk53.osm at gmail.com> wrote:

> Hi Tom,
>
> It's a fairly complicated issue, so not sure if these notes will help you.
>
> The easiest ones are woodland & scrub:
>
> * *Woodland* will generally consist of trees > 5m at maturity (so you can
> use natural=wood for saplings, very pertinent in areas where the National
> Forest is planting new woods). The number of tree species which one might
> regularly encounter doing this is quite small (10-15 perhaps), and often
> characteristic of quite a wide area (Ash in the White Peak, Oak in Wales,
> Beech in the Chilterns & so on), or particular habitats (Alder & Willow on
> wet floodplains). Some wood types dominated by native species are rare to
> very rare (Limes, Elm, Yew, Hornbeam come to mind) and will be rarely
> encountered. I think clumps of Holly in woodland ("shaws) still count as
> woodland. Many other native species of tree (Cherry, Rowan, Crab Apple,
> Goat Willow, Field Maple etc tend to be isolated specimens in woods
> dominated by a different species.
> * *Scrub* will consist of woody plants predominantly under 5 m. Hawthorn
> & Blackthorn thickets, Gorse, Broom, invasive Rhododendron, most Willows
> (not Crack or White Willow which are trees) & Bramble all qualify. It's
> relatively straightforward to produce a list of woody plants which
> typically form scrub, so recognising these can help.
>
> * *Wetlands* are also generally straightforward, with relevant subtags.:
> marsh, bog, reedbed etc. There are some minor issues as to whether reedbed
> also covers areas of Bulrush/Reedmace (certainly true in Germany where the
> standard word is broader in meaning).
>
> The following tags have problems, mainly in that they are so broad in
> usage to be ecologically meaningless.
>
> * *Heath* is less easy than it looks. The first thing to say is that the
> OSM use of natural=heath does not accord with an ecological one. Most of
> the upland areas mapped in Britain as natural=heath are either acid
> grassland or blanket bog. As Corine has a code for Moors and Heath (3.2.2,
> see https://wiki.openstreetmap.org/wiki/Corine_Land_Cover#Tagging), this
> also applies in much of Europe.
>
> Proper heaths will have lots of plants belonging to the Heath family
> (Ericaceae): Common Heather, Bell Heather, Bilberry, Cowberry, Bearberry.
> Also Crowberry and dwarf Gorse species (< 1 m and less spiny than Common
> Gorse) are common dominant species. Bracken is quite common in heathy
> places, and there's often a mosaic of proper heath & grassy bits. In
> lowland Britain I think there's pretty reasonably accord between
> landuse=heath and what ecologists classify as heath (aside from some
> misinterpretation of imagery)
>
> There are significant differences between actual heath and the other
> upland habitats. For instance anyone who has walked across Kinder Scout
> knows that he apparent surface of heather belies a lot of treacherous bog,
> completely different from the Eastern Moors near the Longshaw Estate.
> Upland grassland which is very common does not seem to have been mapped
> with any kind of tag at all. Much of the higher hills in Snowdonia are of
> this type of grassland.
>
> * *Meadow*. landuse=meadow is used for a very broad range of agricultural
> grasslands, and has little or any relationship to what a meadow means
> ecologically. Most of the land tagged with this will be agriculturally
> improved grassland, but in upland Britain may also include poorly drained
> unimproved grassland, often recognisable by the presence of clumps of
> rushes in aerial imagery. Unfortunately this means we have no adequate way
> of mapping *Proper meadows*. These are floristically rich traditionally
> managed meadows, nothing at all like the landuse=meadow tag which seems to
> largely mean farmland which is not arable. These are really quite rare now
> in Britain, to the extent that many people will never have encountered one.
> Again existing tagging makes it hard to find a way actually mapping them is
> an easy to use meaningful way. The most important way to assess any
> grassland is to look down and see how many different plants you can see
> round your feet. In general improved grassland will have very few, whereas
> true meadows will have loads.
>
> * *Bracken*. Bracken is technically a herb (it's growing points are not
> above ground in winter), and habitats dominated by it belong to a class
> called tall herb vegetation. I don't think we have a tag for dominant
> stands of bracken. Somewhere I once read that about 1% of the world's land
> surface is covered by Bracken so perhaps it deserves it's own tag. (But
> also see comment about bracken in heathland).
>
> Long ago Tim Foster suggested using something called Phase 1 Habitat
> Mapping as a way of supplementing these top-level OSM tags in such a way to
> represent more coherent ecological units, but without forcing every mapper
> to use them. In a somewhat desultory way I keep adding bits to the relevant wiki
> page
> <https://wiki.openstreetmap.org/wiki/Plant_Community/UK_Phase_1_Habitat_Classification>.
> The manual referenced on that page has a good section of how to classify
> different habitats, although it does make extensive use of scientific plant
> names. Helpfully, the whole of Wales was mapped by CCW/NRW with Phase 1 and
> it is available as open data. If you know places in Wales looking at how
> they were classified can often help in making choices elsewhere.  There are
> also open data from Natural England for particular habitats (e.g., salt
> marsh, calcareous grassland) which can be downloaded or visualised on the
> MAGIC site. Some councils also provide online listings of the more
> ecologically important sites within their boundaries, these days called
> Local Wildlife Sites (formerly SINCs), and if you are lucky a reason for
> the listing.
>
> These days there are some excellent apps for mobile phones which help
> identifying plants, through use of machine learning. Personally I like
> iNaturalist, but there are around 10 or so which are widely used. They are
> an excellent way to obtain information, to learn more, or just connect a
> plant one recognises with a name. The iNaturalist website allows browsing
> an area to see what plants are around, or just looking at lots of pictures
> of a given type of plant.
>
> Jerry
>
>
>
> On Wed, 15 Sept 2021 at 21:34, Tom Crocker <tomcrockermail at gmail.com>
> wrote:
>
>> Hi fellow mappers
>>
>> I was wondering if anyone has summarised how to distinguish grassland,
>> heath, scrub and wood and the common plants or features in Britain that
>> help define these for the non-botanist like me.
>>
>> While many places are easy to classify (acres of heather or mature beech
>> trees) I'm often unsure of where to draw the line. For example, when should
>> I see holly and hawthorns as wood instead of scrub (if ever). Do gorse,
>> broom and bracken belong with heath or scrub? How about an area of brambles
>> or nettles?
>>
>> I have seen the Heath wiki talk page about distinguishing heath and scrub
>> which is useful, but some of the comments are contradictory and I don't
>> know the Latin names to make much headway with the linked Wikipedia
>> articles. if no-one else has put something together I'd like to help
>> compile this, for my benefit if no-one else's. Of course, there would still
>> always be judgements to make and areas for which there's no perfect answer,
>> but a handy guide might ease that process.
>>
>> Thanks in advance.
>>
>> Tom
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>
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