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Module 3; June 2002.
Question 6
a) i)
Edaphic Factor: Mineral Content
Difference in the two woodlands: the soil under the larch tree forest would be more mineral rich
than the soil under the oak trees.
Explanation for difference: the reason for this is due to the larch leaves taking longer to decompose
and accumulate on the ground. This means that the minerals from the many years of decomposing
leaves are transferred to the soil making it mineral rich. It also prevents the soil from becoming
water-logged meaning there is always a concentration gradient for the plants to uptake these
minerals and therefore they live longer.
(ii) Another edaphic factor that could affect these two woodlands is sunlight availability for the
plants growing below the tree canopy.
b) i)
In order to sample the amount of herb layer plants in each woodland you would avail of the use of
quadrats. Random sampling would be used such as generating pairs of random numbers using a
calculator to form coordinates. This will increase the validity of the results and if a sufficient amount
of quadrats are used an accurate estimate of the number of herb layer plants in each habitat can be
made. Using the quadrats will allow you to calculate percentage cover which makes us of a point
frame which records every time the needle will hit a herb layer plant. You could also calculate the
density which is the number of individuals of each species present in the quadrat. Frequency can
also be calculated as it is the chances of finding a named species with any one throw of the quadrat.
This can then be compared with the results of the other habitat as they results will be recorded in a
table. To ensure that it is the edaphic factor that is causing this change in both habitats you must
measure the mineral content of each habitats soil by testing it’s mineral content and matching it to
the number of herb layer plants found in each woodland.
ii) A suitable graph technique to compare the number of herb layer plants found in the larch
woodland and the number of herb layer plants found in the oak woodland would be a bar chart. It
would have the name of each woodland on the x axis and the density of the herb layer plants on the
y axis. The data would be laid out clearly for us to compare the two woodlands.