Complex sentence: Urban gardens are generally created to make a positive contribution to their communities, however some arguments have been made that urban gardens promote gentrification because they are placing their needs above those of the underrepresented groups in their community.
Split into simpler sentences: Urban gardens are generally created to make a positive contribution to their communities. However, some arguments have been made that urban gardens promote gentrification because they are placing their needs above those of the underrepresented groups in their community.