{"id":243,"date":"2021-08-31T11:48:40","date_gmt":"2021-08-31T11:48:40","guid":{"rendered":"http:\/\/stuarthedley.co.uk\/blog\/?p=243"},"modified":"2021-09-17T14:07:48","modified_gmt":"2021-09-17T14:07:48","slug":"herefordshire-oak-recording","status":"publish","type":"post","link":"https:\/\/stuarthedley.co.uk\/blog\/herefordshire-recording\/herefordshire-oak-recording\/","title":{"rendered":"Herefordshire oak recording"},"content":{"rendered":"\n
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We have to be (1) consistent about identification and (2) record in a productive and meaningful fashion.<\/p>\n\n\n\n

1              Identification<\/p>\n\n\n\n

Quite a lot has been written on the subject.  There are mathematical formulae (equivalent to the same thing Stace advocates for birches) but learning to see and weigh up the most important characters more quickly probably remains the most productive way forward, perhaps coupled with DNA analysis when such things become practicable.  The illustration gives a diagrammatic representation of the nine most important (seven leaf characters, two fruit characters).  Other characters exist, including tree and bud form, but I\u2019m looking for a relatively quick win for moving forwards, not an intractable debate. I suspect stellate hairs are probably the single most powerful indicator of the sessile oak genome; pedunculate oak lacks such a single trait but lobing type, auricles and intercalary veins seem most useful.<\/p>\n\n\n\n

The (great) majority of trees in Herefordshire appear to be introgressed hybrids, a situation different to many other counties in Britain, and to most counties in the lowlands to which we are often compared.<\/p>\n\n\n\n

2              Manner of recording<\/p>\n\n\n\n

Hybrid oaks have been recognised for a long time, but we have not managed to nail a shared appreciation of the nuances of the situation in our County.  I have allowed lines for five entities on the 2021 revision of the County recording sheet in order to progress our understanding and perhaps shed light on the situation nationally.  These are the species (1) Pedunculate Oak Quercus robur <\/em>and (2) Sessile Oak Quercus petraea, <\/em>(3) their hybrid Quercus x rosacea, <\/em>plus two introgressed forms sitting either side of the hybrid which could be understood as three-quarter \/ one quarter genome plants.  Earlier authors have used the terms \u2018forma sub-robur\u2019 and \u2018forma sub-petraea\u2019 for these, though they are not formally described names and are highly unlikely to be 75%-25% combinations! I am suggesting a five-type recording approach because Herefordshire is clearly neither covered by \u2018good species\u2019 nor by uniform, \u2018conveniently mid-point\u2019 Quercus x rosacea<\/em>, nor by a completely indecipherable, smooth gradient of forms.   It seems likely that modern-day distributions reflect the species\u2019 preferred niches, but in a blurred form. <\/p>\n\n\n\n

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We could meaningfully test this idea by building up a picture of oak presence in each of our National Character Areas (NCAs, see left), an established, workable landscape-biodiversity framework. Starting in the N and progressing clockwise these are (1) the North-West Herefordshire Hills (2) the Herefordshire Plateau (3) the Malverns (4) South Herefordshire (5) the Lower Wye (6) Black Mountains and Golden Valley and, finishing in the middle, (7) the Herefordshire Lowlands.  (The Woolhope Dome should probably be split from South Herefordshire for our purposes into a subsection of South Herefordshire.) We will almost certainly find, given the east-west spread of the county and the differences in geology and soils, that the five oak forms partition differently in each NCA, but no-one has tried to look at this yet to see just how strongly these things continue to exert an influence on oak choice. In my NCA, the Black Mountains and Golden Valley, still relatively wooded, old woodland is almost exclusively dominated by the sub-petraea<\/em> oak, with good material of Quercus petraea <\/em>apparently very rare, whilst hedgerow oaks in the valley-bottoms are as often sub-robur<\/em> oak; I have been unable to find any pure robur<\/em>.  Elsewhere I have seen genuinely good Quercus petraea <\/em>in the North-West Herefordshire Hills (Downton Gorge, to be precise), and, perhaps, sub-robur<\/em> oaks as woodland dominants in South Herefordshire (Aconbury Hill).  But we need more feet and inquisitive eyes on the ground. <\/span><\/p>\n<\/div><\/div>\n\n\n\n

Not a lot will be gained by simple tetrad recording alone, even with a shared appreciation of the entities under study, because as with so many other taxa, an understanding of relative abundance is what is needed.  I would like to see Herefordshire botanists informally adopt a tetrad (or indeed a parish if that seems more meaningful) in order to contribute to a county-wide NCA-based investigation into oak.  That\u2019s eight volunteers I\u2019m looking for!<\/span> (Eight NCAs counting the complex Woolhope Dome, with two studies probably needed in the very large Herefordshire Lowlands, minus me at work already in the Golden Valley.)<\/p>\n\n\n\n

All I\u2019m asking is that once you have chosen a study area, you systematically look at the oak trees within it over two, three or more seasons. There is no particular hurry.  Take in the variety of habitat \u2013 woodlands (on both hill and floodplain, if you have the two), plus hedgerow trees and other standards. Sharp divisions in soil type may well generate different findings, and findings from singletons at odds with the rest of the picture may be an indication of planting; Quercus robur <\/em>is likely to have been favoured in many instances in the past.  I have devised a little recording sheet \/ aid memoire which I have found useful to capture and summarise observations which I am happy to share for those participating.<\/p>\n\n\n\n

I realise that working to five divisions of a gradient as opposed to two or three can be seen as kicking the can down the road.  I thus propose that we interpret these five divisions as follows:<\/p>\n\n\n\n

entity<\/td>Proposed interpretation<\/td><\/tr>
Pedunculate oak Quercus robur<\/em><\/td>In a sample of several leaves from the tree, basically all conform to all characters; fruits also to be used in season. Ie, a restricted interpretation of what is often recognised as Pedunculate Oak.<\/td><\/tr>
Sub-robur<\/em> form<\/td>A sample of several leaves from the tree display clearly mostly robur <\/em>characters but different leaves may also manifest one or two petraea <\/em>characters<\/td><\/tr>
Hybrid oak Quercus x rosacea<\/em><\/td>Leaves display on the whole an approximately equal mix of characters from the two parent species. (In my limited experience in the Golden Valley such trees are not common)<\/td><\/tr>
Sub-petraea<\/em> form<\/td>A sample of several leaves from the tree display clearly mostly petraea <\/em>characters but different leaves may also manifest one or two robur <\/em>characters<\/td><\/tr>
Sessile oak Quercus petraea<\/em><\/td>In a sample of several leaves from the tree, all conform to all characters; fruits also to be used in season. Ie, a restricted interpretation of what is often recognised as Sessile Oak.<\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"

We have to be (1) consistent about identification and (2) record in a productive and meaningful fashion. 1              Identification Quite a lot has been written on the subject.  There are mathematical formulae (equivalent to the same thing Stace advocates for … Continued<\/a><\/p>\n","protected":false},"author":3,"featured_media":261,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"kt_blocks_editor_width":""},"categories":[9],"tags":[],"_links":{"self":[{"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/posts\/243"}],"collection":[{"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/comments?post=243"}],"version-history":[{"count":13,"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/posts\/243\/revisions"}],"predecessor-version":[{"id":262,"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/posts\/243\/revisions\/262"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/media\/261"}],"wp:attachment":[{"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/media?parent=243"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/categories?post=243"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stuarthedley.co.uk\/blog\/wp-json\/wp\/v2\/tags?post=243"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}