This dataset contains Cynipid gall abundance from an oak provenance trial at Petite Charnie in France. 2400 trees were sampled from 20 provenances of Quercus petraea and Quercus robur in 2008 and 2009. Cynipids have two gall generations each year so trees were sampled in spring (sexual generation) and autumn (asexual generation). 10 twigs were surveyed for galls on all parts of the terminal shoot (buds, leaves, stem, catkins) from each tree in spring and autumn. Counts were made for each species and generation.
Publication date: 2015-08-21
Samples were taken from an established provenance trial. Provenances are represented by two or three distinct plots (parcelles), each a replicate set of 24 trees planted in four columns of six trees, with spacing of 1.75 meters between trees within columns and three meters between columns. Plots of 8 different randomly selected provenances are aggregated into blocks, with the position of blocks randomised within soil zones. Samples were taken from a subset of provenances from trees in the internal rows of the blocks to minimise edge effects. Cynipid gall abundance was sampled using a standardised sampling protocol. 10 twigs on each tree, each consisting of the last two years' growth, were removed and for each twig the galls on all parts (buds, leaves, stem, catkins) of its terminal shoot (a module of woody growth from the previous year carrying the new leaves) were counted. Galls were identified to species and generation in the field using a morphological key and extensive field experience of the surveyors. After data collation and transcribing into electronic format, unusual values were checked.