I'm an ESL student, and trying to write an paper. I found it very confusing on the usage of suggest. I have asked a proofreader for help, and the proofreader changed the my sentences like the following. But I think I heard that the that clause after "suggest" can only use the infinitive of the verb (be) rather than "is" or "was". So is this "...suggested ecotourism be nature-based..." is the correct way or the following are correct?
But what is ecotourism? This is not an easy question to answer, as there are various definitions. Weaver & Lawton (2007), for example, suggested ecotourism is nature-based, focuses on learning or education and benefits the environment and local economy. More recently, Buckley (2013) argued ecotourism is also concerned with sustainability, although most government agencies regard ecotourism as nature-based tourism and do not mention sustainability. Fennell (2014) also suggested local culture was a part of the ecotourism experience, defining ecotourism as nature-based tourism that focuses on preserving the environment, benefiting the local economy and educating travellers.