Complex sentence: Most of the trees including the magnolia trees which defined the campus and gave it its secluded character (and celebrated in the school's alma mater) were uprooted or otherwise destroyed including 5 magnolia trees that were purchased for the school's new Granby campus.
Split into simpler sentences: Most of the trees, including the magnolia trees (celebrated in the school's alma mater) that defined the campus and gave it its secluded character, were uprooted or otherwise destroyed. This included 5 magnolia trees that were purchased for the school's new Granby campus.