Oregon’s forestry sector, once the state’s driving industry, has scaled back dramatically, the result of modernization and reduced harvests since the 1990s. Yet the industry is still adding workers and looking to replace retirees — now with a growing demand for technical expertise. The industry’s employers say they’re struggling to fill the jobs they have. Retirements have thinned the ranks, turnover is high and new workers are hard to recruit. Adding to the trouble, a workforce study found the sector will add 3,400 jobs annually through 2030. In particular, the report found Oregon’s colleges and universities aren’t producing enough forestry graduates to meet demand — suggesting Oregon employers might have to recruit from elsewhere to staff some of the highest-paying jobs in a signature sector. It’s a counterintuitive finding for an industry that’s been cutting further in recent months through the closures of mills and factories. Officials say that’s because there’s more to forestry work than logging.