Fitter's research interests include plant and microbial behaviour in a changing world; functional ecology of roots and mycorrhizal associations under field conditions; root system architecture; carbon cycling in soil, especially in relation to mycorrhizas; phenological responses to climate change.[2]
Alastair Fitter is the son of the naturalist and author Richard Fitter (1913–2005), and together in 2002 they published an article in Science on the changing phenology of wild flowers due to global warming. They have also collaborated on numerous field guides and other natural history books.[3]