Week 22: Of Chalk Grasslands In Hemel Hempstead

Salad Burnet (Sanguisorba minor) (I hope!), the indicator species for chalk grassland, on Further Roughdown, overlooking Hemel & the KD Tower

“Chalk grasslands have been likened to rainforest for the diversity of species they hold. But they are being lost at an alarming rate due to changes in land use causing the decline of grazing: it's estimated that we've lost 80% of our chalk grassland over the last 60 years.” BBOWT

A statement like that makes you sit up and take notice. I was fortunate to be able to attend the “Chalk grassland flowers and grasses” seminar at the Field Studies Council (FSC) in Amersham last weekend. It was led by the incredibly knowledgeable and wonderfully approachable Brenda Harold. On the up side, I could at least identify and discuss the place of Yellow Rattle within the ecology (ref Week 19). On the down side, I’d run out of energy by lunch time and it took 2+ days to recover. Well worth it though and I'd do it again, given the choice. Anyway, this week has been all about enjoying the chalk grassland at Roughdown Common and seeing it through the lens of my new knowledge.

A few notes from the course, in case they are of interest. If not, just skip it.

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Grassland

Semi-natural, Unimproved land

• Semi-natural i.e. the land has been cleared of trees by man and grazed or mowed for hay. All the plants are wild/self seeded. 
• Unimproved i.e. no mineral fertilisers or lime or other substance added.

Grasslands in general are dependent on the history of grazing, which virtually ceased after the second world war in the UK. This is where “conservation grazing” comes in (ref my “sheepish explanations of ecology” post). Sheep, rabbits, any kind of grazers, are important to prevent “thug species” like dogwood, hawthorn, bramble, thistles etc taking root, monopolising nutrients and overwhelming the smaller species and reducing species diversity.

Chalk Grassland

Calcareous, alkaline, free-draining, drought-prone soil. Low in nutrients (thus no good for agriculture) and often on slopes (so no good for building/development).

To the uninformed it is useless and even costly. Except, by the wonders of nature, it is also the most species rich in terms of the plants which thrive there and the wider ecology which follows. Incredibly, you can have up to forty different species per square metre of grassland. The key is low nutrients and high pH. Low nutrients otherwise the thug species move in and drown everything else out. High pH otherwise the acidity destroys and only the few strong or tolerant survive. It is one of the rare environments where nature is at its richest. And yet, as the BBOWT states, almost 80% of the UK’s  “unique and fragile chalk grassland has been lost....due to intensified agricultural practices, development and mismanagement.” It makes me appreciate all the more the value of places like Roughdown Common, the obligation to protect it and the need to support those who manage it.

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Ok, context set. Chalk grassland to enjoy.

Where to begin? The orchids! They really are quite spectacular at the moment. The dell, on the north side of Lower Roughdown, is cradling Common Spotted and Pyramidal orchids (both calcareous soil indicators). Something seems to have nibbled heartily at all of the Twayblades but the tell-tale leaf pairs remain. The Selfheal is also flowering now. A Robin was busy collecting food for an insistent youngster, the chiffchaff keeps on singing and a Jay bounced through the trees trying hard to remain inconspicuous.

Up on the south-west side, the bank which runs along the A41, the orchids are breathtaking. I’ve never seen anything quite like it. Swathe after swathe of deep pink/purple, white and every colour in between rising up from the earth, each a beautiful specimen, together a feast to behold.

Walking south-east along the bank, I came across a pair of Bee Orchids (Ophrys apifera), which was a lovely surprise. And, I spent a couple of contented hours completely absorbed in the nature around the grassy bank, just before you reach Further Roughdown. It was quite literally jumping with life. Meadow Grasshoppers stridulating (singing), causing grasses to ping every so often as they launched themselves on their merry way. All colours represented. This one (below) is the green variety, and could possibly be a young adult, judging by the short wings, but there were plenty of red/brown examples too. Grasshopper fact to throw into conversation next week: their ears are on their bellies (cool, eh). “On each side of the first abdominal segment, tucked under the wings, you'll find membranes that vibrate in response to sound waves. This simple eardrum, called a tympana, allows the grasshopper to hear the songs of its fellow grasshoppers.” More facts here if hoppers are your thing.

Dock bugs and Common green shieldbugs were flying between plants, butterflies too (Marbled Whites, Meadow Browns, Ringlets, a Skipper species (smaller than the Large Skipper but too quick for me to identify), Small Tortoiseshell, Speckled Wood and a few remaining Common Blues). Then there were the moths. Numerous Burnet Companions, Six-spot Burnets, a Cinnabar and three new ones for me, Knapweed Conch (Agapeta zoegana), Shaded Broad-Bar (Scotopteryx chenopodiata) and Celypha lacunana. A Great Tit family came through noisily and an adult Dunnock was trying hard to keep a squeaky juvenile well fed.

Knapweed Conch (Agapeta zoegana)

Shaded Broad-Bar (Scotopteryx chenopodiata)

Out on Further Roughdown, the Pyramidal orchids outnumber the Common Spotted, I think. They are not so numerous but the discreet clumps are fresh and vibrant. A few Swallows were hawking low over the ground, after the insects (and guaranteed to beat me to it!)

Further Roughdown Pyramidal Orchids overlooking Hemel and the KD Tower. 

Also in the mix are Birds-foot-trefoil, Fairy Flax, Yellow Rattle, White Clover and many more species besides (the names of which have yet to take root in a brain cell)! 

And, to round off this week's post, the Oak

Week 21/B: Brilliant, Bountiful, Box Moor Bee Orchids

My Tuesday had begun with blue sky but something of a dark mood. The discovery of the fantastic little Bee Orchids (Ophrys apifera) not only lifted my spirits but filled the morning with new colours, shapes and textures (how velvety does that “bee” flower look?!). As I mentioned in the previous post, there were more than 92 spikes in this one small area! From what I understand, it is considered rare locally and hasn’t perviously been reported at this site. I got utterly engrossed in photographing them. Lying belly-down in rabbit droppings was neither here nor there. It wasn’t until I needed the loo, my stomach was rumbling, my back was hurting, my elbows were sore (from propping myself up) and my knees were pretty much welded bent, that I reluctantly (and slowly) creaked my way to standing and headed home for a bacon butty. Here are a few memories from that morning… [as ever, higher resolution images in a set on Flickr here]

It seems that the Bee Orchid isn’t rare per se, but the habitat it can especially thrive in is becoming increasingly so i.e. open grasslands and, frequently, chalk (and limestone) grasslands. This is a reason why it isn’t seen locally. Box Moor Trust land is one of the few places left for it to colonise. It’s a perennial, dependant on mycorrhizal fungi for nutrients, and is self-pollinating in the UK (we don’t have the right bees here (honestly!)). Travel to the balmy Mediterranean and you’ll encounter the patently very sensible (but easily fooled) Solitary bee (Eucera). This pollinates plants in the southern regions by falling for the mimicry of the look-a-like “bee” flower. Males are drawn in and even “attempt to mate with [the flower], transferring pollen in the process” (silly Bee!). Self-pollination is just as interesting. Basically, as the flower develops, the pollinia [two yellow blobs of pollen grains] are released from the green, curved arch in which they are held (this is the anther, the male part, and the structure you can see overhanging the “bee”). They then hang loosely on yellow threads (caudicles) and are blown against the receptive surface of the stigma (the female part), et voilà! Just below the stigma, at the base of the reproductive column, is the ovary (the part of the flower that contains embryonic seeds, called ovules). According to Wikipedia, this Orchid is unusual in that “in some years they appear in great numbers, then sometimes only reappear after an absence of many years.” How ever it reproduces, it is clearly a plant to be made the most of whilst it is around!

I was fortunate to be able to return to the Bee Orchids on Thursday morning for a short time, with a few rough ideas for compositions. I wanted to capture the context and the proportions. I also hoped to capture the texture of the “bee”, show the pollinia and also photograph a bud which was in the process of opening. I hope you enjoy the results as much as I did achieving them…

Velvety "bee" & Pollinia pair

Bud opening in progress

Compared to Dr Pepper!

Week 21/A: The Power of a Little Flower

Tuesday morning the sky was blue, the sun was shining and I was feeling absurdly overwhelmed by the possibilities for a walk around Box Moor. Blue skies in particular are so rare that you feel as though you have to ring every last ounce of potential out of days like that. Just the thought of it can be exhausting!

I arrived at Dellfield with only one aim. To photograph the Oak. Good light and blue sky is like being faced with an open goal. Too many options, too rare an opportunity to miss: bound to mess it up. Anyway, having snapped the Oak, I took a wander around the meadow. A Silver Y (Autographa gamma) fluttered up from the grass, numerous Burnet Companions floated by, and there were mating Soldier Beetles (Cantharis rustica) and Scorpion flies (Panorpa communis) galore. I found a single flowering Poppy and a snazzy Five- or Six-Spot Burnet caterpillar (not sure which). Photographing them was like something out of a Laurel and Hardy sketch - every time the breeze died down, I’d just about compose the shot, be ready to fire, and a puff of wind would scupper my efforts (although not entirely, as you can see). Over and over, this happened until I eventually gave up, feeling increasingly paralysed by the potential of the day and my inability to capitalise on it.


I moved on from Dellfield and up to Preston Hill to catch up with the Broad-bodied Chasers. One male was definitely still around. I then carried on through Hay Wood and onto Bovingdon Reach. My idea was to walk to Ramacre Wood and check again for Spotted Flycatchers. Little did I know my morning was about to be transformed by the discovery of a little flower. There I was, somewhat dejected and flummoxed and, down there, just to my right, what did I spy? A Bee Orchid (Ophrys apifera)! I couldn’t quite believe my eyes. But, true enough, there it was.....and then, there was another. And another. And another. And this went on and on. In one small area, there must have been around 30 spikes of Bee Orchids*. Dejection was quickly replaced by pure joy! From what I can gather, they have not been reported here before and are considered rare for the area. I suspected they were something special when I found them and I finally knew how I was going to best use this beautiful morning of near perfect light and potential: photographing the Box Moor Bee Orchids. And, they deserve a post of their own...

*I went back to Bovingdon Reach on Wednesday evening, sure that I must have over-estimated the number of Bee Orchids. I did a fairly thorough count and totalled 92 spikes!

Left, 19 February 2014; Right, 10 June 2014