HELP!! How does light intensity affect the leaf size of bramble!!

help i need some guidance for my biology A2 coursework, my title is; How does light intensity affect the leaf size of Bramble.

I conducted a prelim on 2 sites (doing shaded and non-shaded at both sites) to help justify which site shows the greatest difference between leaf size and light intensity. In my final investigated i conducted at Rushy Plains (in epping forest) i done a 5m x 5m area using random sampling to generate 6 coordinates.

i measured light intensity (lux), soil moisture (by weighing soil before and after it was in the microwave), soil compaction (using a penotrometer), canopy cover (using a grided quadrat).

for my coursework i need a lot of background knowledge about bramble, such as its optimum growth conditions, can somebody please help me by posting a good source of information regarding bramble, or even somebody else's coursework with the same title or even just general information stating how different abiotic factors have an affect on bramble. thanks..