Sijtsma holds a PhD in economics since 2006. He publishes and teaches subjects in economic geography, valuation of nature and landscape with special attention for islands, and evaluation of spatial plans and projects. He develops innovative ways of valuation and evaluation within the contexts of regional economic development, urban and regional spatial planning and protected area governance. Sijtsma is director of the Rudolf Agricola School for Sustainable Development of the University of Groningen, where over 200 scholars engage in interdisciplinary research and education for sustainable development.