Offwell Woodland & Wildlife Trust

Promoting the British Countryside

HomeAbout usConservationEducationWildlifeHabitatsMapsSearchResourcesSponsorsAn Ecological Sampling Exercise
Processing & Interpreting Raw Data

Exercise Answers
  Bluebell % Cover in Random 1m2 Quadrats on the Heathland Restoration Project areaAutumn CutSpring CutAutumn CutSpring CutQuadrat No.Strip 1Strip 2Strip 3Strip 4(undivided)TopBottomTopBottomTopBottom12020406025301245251070551513908088010014525204591051010206020866201515458627702084013600830152010497549525254567-0105085152427-0Mean3218.147.928.324.41.5Overall34.52538.113 The differences between the top and bottom of the strips are not of the same magnitude in all the strips. Strips 2 and 3 have a similar degree of difference. Thus, the Bluebell cover in the bottom of strip 2 was approximately 56% of that in the top half of the section, while in strip 3 this figure was 59%. The percentage of Bluebell cover in the bottom of strip 4 by contrast, was only 6% of that in the top. This is a very substantial difference.These differences in magnitude between strips may be partially explained by looking at the difference in length of the strips. The strips are longer and cover a greater East / West area as you go north across the project site. Thus strip 2 is the shortest and strip 4, the longest.The shorter the distance between the influencing top and bottom areas of woodland, the less direct sunlight the intervening ground receives (see the diagrams below). Shade will cover more of the total area of strip 2 in the morning, before the sun rises above the lower trees, compared to strip 4. The whole of strip 2 will also be completely shaded long before strip 4, as the sun sinks behind the upper woodland. This means that the differences in microclimate between the top and the bottom are less marked in strip 2 than in strip 4 and the Bluebells are therefore less affected.Short Distance between Bordering Trees
Longer Distance between Bordering Trees
Factors apart from strip length will also be involved. These might include differences in the height of the immediately adjacent trees, which would increase or decrease local shading (see Section 3 in the picture below). Differences in other environmental conditions, such as drainage and soil conditions, as well as in the initial distribution of the Bluebells on the site, will also influence the observed % cover .    Looking south across sections 1 to 4 in the late morning in May. The sun is to the top left of the picture. Shadows would be much longer earlier in the day , as well as at the same time of day in the winter, when the sun is lower in the sky. Note how the edges of sections 1, 2 and 3 are shaded, while corresponding areas of section 4 are in full sunlight.  Answers Contents