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Thursday, March 15, 2012

Botany Study Group. Plant survey, field training.

Heart of the Levels Local Area Group of the Somerset Wildlife Trust. March 2012

Report on our Botany Study Group field field work visit to Batty's Piece, Curry Rivel, March 6th 2012.

Members were given an introduction to vegetation identification techniques. In other words , how to identify in the absence of flowers. Identification is the key to any surveying technique and is most difficult when plants are not in flower.

Batty's Piece is a 4 acre private nature reserve off Holdens Way owned by a group of local residents and maintained as an unimproved grassland meadow.

With fine weather it was ideal for this introductory session. The field was purchased in 2005 and professionally surveyed soon after. Approximately 120 different flowering and grass plants have been recorded. It was declared a Local Wildlife Site in 2007. A County Council Grant was obtained in 2008 for planting a new 200m hedge on the north side of the field. The planting was carried out by members of the Syndicate.

Members of the Group were introduced to a range of surveying techniques commonly used by amateur and professional surveyors. Anne and John Bebbington led the session.

Members initially spent 10 minutes or so to looking closely at the two areas selected for our field work and then all were given a brief description of the general principles of surveying and the methods to be used on this visit.

Members worked in pairs and were tasked with surveying two 7 metre square plots, at widely separated parts of the field which appeared to differ in their vegetation. Pairs first carried out a subjective assessment of 16 selected species in each of the two areas using a modification of the Braun-Blanquet scale (ACFOR).

A total of 12,  25 x25 cm square metal quadrats were then placed at 12 random co-ordinates in each plot and the presence or absence (frequency) of the selected species recorded. This sample size gave us an acceptable coverage of between 1-2% of the total plot size.

The data was collated over lunch in Drayton Village Hall and then discussed. The subjective assessment showed some differences between the two areas and this was confirmed by the frequency data. There were some discrepancies between the results recorded by the two methods and reasons for these were considered..

In further discussion the relative accuracy of the two methods and how and when they should be used was discussed . Members were also introduced to techniques used by the Somerset Botany Group and in National Vegetation Classification Surveys. We hope to spend a field day using National Surveying techniques next year.

The fine weather made the day a most successful and enjoyable experience. The next session in April will be looking at spring wild flowers at a different venue.

David German 12.03.12

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