Published at 11:06, Thursday, 10 May 2012

EARLY spring is perhaps the finest time of all to both study and enjoy our emerging flowers and wildlife when visiting our woodlands.

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Summer visitors begin arriving, like the chiff-chaff in late March and a little later, the willow warbler. The other day I saw the rapid flight of a bright yellow butterfly between the leafless branches – the brimstone, indeed a yellow fairy. Then, by the wood’s edge, a starling inspecting a hole in a tree – nothing unusual, perhaps, except that this bird, a gifted mimic of the sounds of others and a serious consumer of the leather jacket pests of our grasslands, is now in serious decline.

Last month, April, just wouldn’t be the same without our wonderful wild primroses making a show along our railway banks a little north of Whitehaven Station and in our woods and lanes. Among our trees our woodland flowers were at their best – at what is known as the prevernal aspect of our woodlands, before the leafy canopy closes over by the second week in May.

The other year we did a study in Haile Great Wood, near Egremont, pegging out squares called quadrats, each of 60x60cms, recording the species in each square as well as its cover, using a five point scale devised by a French worker Braun-Blanquet. We were estimating the abundance of each type of plant in terms of ground cover.

With a cover of 80 to 100 per cent, it is recorded as the maximum of five. Then with a cover value only up to 10 per cent it is recorded as the minimum value on the scale of one. The abundance value of one to five is referred to as a frequency.

We also recorded any birds seen, but studies of animals in the field are always more difficult – they just don’t stay put like plants! Hence we get capture/recapture methods like ringing in birds and radio-tracking devices.

Primroses were in evidence on the banks. Their flowers have evolved both pin and thrum eyed kinds, with the anthers and stigmas at different levels to ensure cross-pollination. But there in the wood are also homostyle primroses, with the anthers and stigma held at the same level.

Slugs love to browse primrose flowers. Think about it – are the homostyles at a disadvantage in terms of reproductive success, when compared with pin and thrum eyed flowers?

The other main problem to tackle in field work is that of distribution of species of animals and plants, or some of their specific forms like the homostyle primrose. How frequently do these occur in different quadrat samples taken from primrose woods, say throughout Cumbria? This frequency of occurrence of primroses or indeed their homostyles, can be recorded on a five-point scale using a concept referred to as constancy. Measuring constancy is especially useful as it gives us some understanding of the geographical distribution of a specific kind of plant, its presence or absence being recorded at each location.

Old railway habitats are especially rewarding for field work involving measuring and recording. One with full public access is at Sandside on the Kent estuary and situated just behind the Ship Inn. It is especially delightful in the spring and I would take adult education students there.

We used a line known as a transect to record the changes in species of plants along the line, correlated with the changes in light intensity, as we moved from the more open trackway to the relatively shaded margins. Birds seen or heard, as well as butterflies and amphibian tadpoles further on in the wetland “lagg” were also recorded.

My wheaten terrier Tipp from Tipperary would be there purely in a supervisory capacity... hmm.

Published by http://www.whitehavennews.co.uk