We've got a site that’s grown over the years to be a decent size (a couple of thousand pages) and we’re trying to make navigation easier and more intuitive for visitors without alienating search engines and losing rankings on pages that rank well now.
The site is established and covers a fairly broad subject – let’s say landscaping. The site was set up initially with some broad categories to cover major topics for the subject area. Each of these categories is in its own directory on the site. So, using the landscaping example, we’d have categories for trees, shrubs, groundcovers, flowers, etc
Over time we’ve accumulated many articles in each category – so many, that the index page for each one has dozens and dozens of article descriptions and links, making it pretty difficult for people to find information we have on the site.
So we were thinking of changing the navigation in some way to make it easier for site visitors. But we don't want to lose the rankings we have in search engines.
One thought was to leave the articles where they are, but create subdirectories for subtopic levels, and just have an index page and list of articles with links in each subdirectory index page. Thus, we'd then have say, landscapingsite.com/trees/oaks/index.html
which would list the articles about oak trees, such a why leaves look prettier this year.htm, toomanyacorns.htm, etc.
The articles, already on the site and with some decent placements in serps would still be in the trees directory, but we'd be moving the internal links to the articles to trees/oaks/index.html
Is that going to cause us to lose the SERP positions we have because we move the internal links? If so, what is a better way to restructure a sprawling, well-ranking site to make it more user friendly and still keep good serp positions.