Improving SEO with your community is a hot topic with community managers. Many minor tweaks can move the needle in the right direction, but the most significant changes come with increasing crawl efficiency.
Recently made changes to Invision Community improved crawl efficiency. By removing thin content pages and being laser-focused on what you want to be crawled, you present a more efficient site ready for crawling. Crawl depth is another metric that impacts crawl efficiency. The more 'clicks' Google and other search engines have to make to get to your content; the less efficient your site is for crawling.