Investigating local distribution and abundance of common cow-wheat Melampyrum pratense in the Blean Woods National Nature Reserve, Kent.

The pre-diapause larvae of the rare heath fritillary Melitaea athalia in the woodlands of southern England utilise common cow-wheat Melampyrum pratense as their primary larval host plant (LHP). Conservation of the heath fritillary therefore depends on the presence and management of common cow-wheat (CCW) in its habitat. For this study, an investigation on the variables affecting the local distribution and abundance of CCW in the Blean Woods National Nature Reserve (NNR), Kent was carried out. Thirty 100m2 grid squares across the Blean Woods NNR were assessed for eight variables thought to affect CCW distribution and abundance. These variables included distance to ant nests, distance to oak trees, light intensity, canopy cover, bare ground cover, soil pH, soil calcium content and oak sapling distribution. A principal component analysis (PCA) incorporating the eight measured variables for each grid square was used to identify the principal components that explain the variation in the data of CCW % cover. The results of the PCA were then used to reduce the number of variables used in stepwise regression and multiple regression models to then identify variables significantly associated with CCW % cover per grid square.

The results showed that oak sapling cover in a sampled grid square was the only variable among those recorded that had a significant effect on CCW distribution and abundance. This could be due to CCW utilising oak saplings in a hemiparasitic manner or simply a case of the species having similar environmental preferences. The statistical analysis also revealed that CCW seemed to be distributed non-randomly and in a patchy pattern across most of the grid squares. In addition, a comparison of CCW cover in grid squares based on abundance records from 2013 and 2018 showed that there seems to have been no significant change of CCW cover in these grid squares during the intervening five-year period.