Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:However, US and MW contrast strongly in protection levels, as US lacks law enforcement on the ground and therefore human disturbance is high (Rovero et al. 2012); 3) Matundu (MT) is the largest (526 km2) forest block in the Udzungwa range, and is predominantly lowland (280–1,000 m a.s.l.; Marshall…
Category: