Offwell Woodland & Wildlife Trust

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Processing & Interpreting Raw Data
Exercise Answers 7- 10
Yes. Because a good pace is approximately one metre in length and because the quadrat being used was a 1m square quadrat, each one metre square within the sampling area had an equal chance of being chosen. Care needed to be taken to ensure that the quadrat was always placed down on the ground in the same way, i.e. bottom left-hand corner just in front of the student. Time of cutting is obviously not the only factor which is influencing Bluebell distribution on the Heathland Restoration Area. Environmental conditions will also be affecting survival rates. This is evident from the clear differences between the top and bottom of the strips. Differences in microclimate across the area will have an effect, as will soil differences. For example, the soil directly beneath trees will be more nutrient-enriched because of leaf decay. Drainage differences due to the slope will also translate into added variation in soil conditions in different areas. Grazing by animals will also affect the Bluebells. Roe Deer and rabbits are both found on the project site. There are no physical boundaries between the sections and they are free to roam and feed as they will. They will therefore have an influence on the vegetation on the site which is irrespective of strip number or management.However, Roe Deer are not herd animals. They tend to browse rather than graze and they do not particularly favour Bluebells (Muntjac, on the other hand, can decimate Bluebell numbers). The rabbit population in the area is also small. Animals are therefore unlikely to be having a significant influence on the Bluebell numbers.Bluebells are also sensitive to trampling. However, sections 1 - 4 of the Heathland Restoration Project area are very secluded and this region is rarely, if ever, visited by  walkers or the general public. Trampling is therefore not likely to be an influencing factor.There is no data available on the original distribution of the Bluebells prior to the start of management. Such data might have pinpointed pre-existing differences between the strips, totally unrelated to subsequent management. Different groups of students sampled different sections. Although the same person estimated the percentage cover within each group, different people were estimating percentage cover in different strips. Errors through observer bias may therefore have been introduced. This can sometimes be considerable.The sampling was also being carried out before the Bluebells had fully developed. Therefore the total area covered by Bluebells was much lower than it would have been at  their flowering time. The lack of flowers also made the Bluebells less immediately identifiable. There was a distinct possibility of confusing sedges and woodrushes (which are common in all the strips) with the Bluebells.The exercise could therefore be improved by sampling later, in May, when the Bluebells were fully developed. The same person should do the % cover estimations in all quadrats. Sampling a greater number of quadrats would also improve the chances of obtaining statistically significant data.Bluebells flourish in the current mild, wet climate of South-western England. The damp climate allows them to grow outside their normal woodland habitat in such open areas as the Heathland Restoration Project site, as well as in permanent pasture and on hedgebanks. If Global Warming results in a more Mediterranean-type climate in the region as has been variously predicted, then the Bluebells are unlikely to survive the increased heat and dryness. Answers Contents