Monday, 2 September 2013

The pondweed's doom

The wet summer of 2012 saw many more of the temporary ponds stay full all year long, especially the shallow flashes and pools in the arable fields. The bare mud may not look an inviting habitat but for the few species that can cope these ponds are a productive refuges. Some more unlikely inhabitants turned up too, notably some plants typical of more permanent water. The left hand picture shows a dense clump of small pond weed, Potamogeton berchtolidii, flourishing in the  exposed shallows of a large pool in the middle of what should have been an oil seed rape crop.

This particular pool fills every year, a distinct dimple at Blakemoor farm not far east of the A1063 road. How the pondweed got there I do not know, although black headed gulls, shelduck, red shank and avocets all loaf around on the muddy margins and may be the vectors. The summer of 2013 has been drier, in fact the warmest, driest since 2006. The middle photo shows the same view in May as the water level falls. Fragments of small pondweed were still scattered across the bed of the pond, hard to see but there is a clump in the red circle. However by the end of August the water had receded leaving the mud to crack and gnarl (right hand image). No pondweed could be found on the crisping surface. Perhaps buried roots will allow the pondweed to re-grow and the pond refills over winter; it will take until next year to find out. It is not often you witness these moments, whether the unusual arrival in 2012 or grim fate of 2013, but pond wildlife is surprisingly mobile and small pondweed is a common plant of many of the permanent ponds. The drying out bowl of the pond is now ringed by chickweed, Stellaria major, and Orache, Atriplex prostrata, much more typical plants of these sun baked field pools.

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