Natural History Dissertation Award 2021

Alexandra (Lexi) with her prize and dissertation supervisor Dr Felicity Crotty

The Royal Agricultural University presented GNS’s sustainable bamboo plaque for the best natural history dissertation at their short graduation ceremony to Alexandra Lloyd studying the BSc (Hons) top-up in Wildlife and Countryside Management for her highest scoring dissertation under the criteria on ‘Tramline orientation effects on aboveground invertebrate dispersal’.

Globally, invertebrates have been found to have declined in abundance and diversity, in part due to the intensification of agriculture. However, with agricultural land covering 70% of the UK and forming a habitat for invertebrates within the soil, crops and hedgerows, farmers and scientists need to work together to discover the best ways to reduce this decline. The relationship between terrestrial invertebrates and agricultural management practices has been widely investigated, however this study aims to assess an area that is often overlooked; whether invertebrate dispersal from field edge is impacted by the orientation of tramlines in relation to the field boundary.

Overall, 646 invertebrates were collected via pitfall traps placed along 100m tramlines from the field boundary, an established hedgerow, to field centre, set over a twenty-four-hour period. These transects were orientated either parallel to the tramline or perpendicular to the tramline. Individuals were identified to the taxonomic family level. Soil compaction data was also collected, using a penetrometer, along the transects.  An analysis of variance was used to analyse abundance of total fauna; Collembola; and predatory species (consisting of combined Coleoptera and Araneae data). In each of the three groups abundance was significantly higher in the perpendicular orientation than the parallel; total fauna (p<0.001), Collembola (p=0.001), predators (p=0.018). No significant difference was found over distance from hedge to field centre for any of the groups studied, nor was there a difference in diversity of samples collected across the transects. There was no significant difference in field compaction between orientation of measurements from the tramlines, however the distance from the hedgerow into the centre of the field did show significant differences (p=0.036), with greater compaction near the hedgerow.

Overall, the results of this study show that tramline orientations in relation to field boundary do influence some above ground invertebrates ability to disperse from the field edge to the field centre. This should be taken into consideration when surveying above-ground invertebrates within agricultural fields. Compaction had little direct impact on the above ground terrestrial invertebrates movements here, however it could affect flora species on which invertebrates rely for habitat and food source which encourages dispersal. Further research is needed to confirm these findings across season and at a range of different field sites.



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