Shrimping at Imber

The Ministry of Defence training ground at Imber village is occasionally open for members of the pubic to visit the village and, in particular, the church. More occasionally groups are allowed restricted access to explore the wildlife of the plain in the company an MoD ecologist.

Last weekend both events coincided for Southampton Natural History Society, so we got a visit to the church as well as the plain in the company of Ian, our experienced and knowledgable guide.

We met just off the plain after a slight delay due in part to roadworks and in part to dodgy navigation. Ian gave us some top tips – roughly translated as “if you see something that looks like it was designed to go bang don’t give it a kick.” He also showed the scale of the plain – roughly the size of the Isle of Wight – and the location of some key wildlife that we wouldn’t be seeing (great expectation management). “The bustards are over there, occasionally we get Montagu’s harriers that way a bit. Stone Curlews? We get them here, but they’ve gone. And those wildflowers you’ve come to see? Well, you see those cows over there……”

But we’d really come to see some of the plants of the plain and, despite the munching cows, we saw it all.

To start though, everyone wanted to see Fairy Shrimps (Cirocephalus diaphanous). Some of the group hadn’t seen them before so we were all up for looking. However, the plain did look bone dry and the shrimps might be fairies but they need a little more than fairy dust to survive. Within a few minutes we did find some water at the bottom of some tank tracks and, yes, a few dozen tiny transluscent shrimps swarming just under the surface. Later examination of the extremely blurry photographs I managed seemed to show most of the shrimps carrying eggs.

Ian told us that the main method of dispersal was through translocation of the shrimp eggs, and that he’d conducted a number of experiments to help demonstrate this. These seems mainly to consist of driving or running through muddy puddles with a variety of tyres or footwear. Big kid! Apparently the mud from feet, shoes or tyres was collected and dried and then rehydrated in a controlled location (a bucket). And lo – behold the fairy shrimps.

I’d always thought the shrimps survived in the dried mud and re-emerged with the rain. Apparently this has as much scientific credibility as swallows hibernating up chimneys.

So that’s the shrimps. Here come the plants, and some photographs which are actually in focus. Nearly. The text is from the Online Atlas of the British and Irish Flora.

Tuberous thistle (Cirsium tuberosum)

Tuberous thistle (Cirsium tuberosum)

Ecology: A perennial herb of old chalk and limestone grassland, often on slopes with a N. or N.W. aspect, and sometimes occurring in rank swards. It spreads by producing axillary basal rosettes to form clonal patches, and also reproduces by seed. Lowland.

Status: Native

Trends: This species is declining in its two main areas in Wiltshire and Glamorgan. The reasons for the decline include habitat destruction by ploughing, coastal erosion, changes in land management and, particularly in Wiltshire, hybridisation with Cirsium acaule. It became extinct as a native in its sole Cambridgeshire locality in 1973, but has subsequently been re-introduced there.

Hairy Rocket (Erucastrum gallicum)

Hairy Rocket (Erucastrum gallicum)

Ecology: An annual, occasionally persisting in quarries and along tracks on chalk soils, but almost always casual on roadsides and waste ground. Lowland.

Status: Neophyte

Trends: E. gallicum was first recorded from the wild in 1863. In Ireland it is more frequent now than it was in the 1962 Atlas. It has spread widely on Salisbury Plain (S. Wilts.) as a result of disturbance from army activity. It is apparently sown in order to bind and stabilise steep chalk road cuttings (Brewis et al., 1996).

Basil Thyme (Clinopodium acinos)

Basil Thyme (Clinopodium acinos)

Ecology: A usually annual herb of open habitats in dry grassland, rocky ground or arable fields. In Britain it usually grows on calcareous soils, whereas in Ireland it occurs on sandy and gravelly sites, including eskers. It is also a rare casual of waste ground, quarries and banks by roads and railways. Lowland.

Status: Native

Trends: C. acinos has substantially declined as a result of more efficient methods of weed control and, in Ireland, gravel extraction. In many areas it is no longer found in arable fields, surviving only in less intensively managed habitats. It is considered to be alien in Ireland (Scannell & Synnott, 1987).

Red Hemp-Nettle (Galeopsis angustifolia)

Red Hemp-Nettle (Galeopsis angustifolia)

Ecology: An annual of arable land, waste places and open ground on calcareous substrates, including limestone pavements and scree; also found on eskers and on coastal sand and shingle. This late-flowering species often fails to set seed within winter-sown crops. 0-320 m (Derbys.).

Status: Archaeophyte

Trends: G. angustifolia was formerly a common cornfield weed in some areas (Druce, 1927), but the contraction in range shown in the 1962 Atlas has accelerated following a shift from spring- to winter-sown crops and cleaner crop husbandry. It is increasing on ground disturbed by gravel extraction in Ireland.