I think generally people who enjoy spending a lot of time outdoors are also people who find themselves over (or under) stimulated in social environments, so yeah introverted.
The taxonomy aspect of being a naturalist appeals to people who like systems and categorization, which I think falls under Conscientiousness in the Big Five personality system as orderliness, or maybe a combo of Thinking and Judging under Myers-Briggs?
The neurodiversity topic would also be relevant here.