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

[SK53]

Hi Tom,

It may also help if you share specific examples: these might be useful in
compiling more general guidance. I've long thought that concrete examples
from places which people are likely to know might be of more assistance
than abstract rules. I'm going to see if I can do something as a diary
entry for places mapped natural=heath & hope to cover the range of major
habitats involved.

Jerry


On Thu, 16 Sept 2021 at 19:20, Tom Crocker <tomcrockermail at gmail.com> wrote:

> 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
>>> _______________________________________________
>>> Talk-GB mailing list
>>> Talk-GB at openstreetmap.org
>>> https://lists.openstreetmap.org/listinfo/talk-gb
>>>
>>
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