Wicken Fen is not a natural habitat. For centuries the Fen has been under the influence of a human population. Irregularly harvested fen crops have created a mosaic of different vegetation types.

Wicken Sedge Fen is one of the few remaining fen areas never to have been drained. The South part of the Reserve (Adventurer's Fen) has been drained in the past, and is now some 2m lower than the northern part, the Sedge Fen. This area is managed differently to the Sedge Fen, with most of the area grazed by cattle or sheep, or left for hay. The cutting of vegetation continues throughout the year on Wicken Sedge Fen. Depending on the area and the vegetation type, these seasonal cuts are carried out on anything from a one year to a seven year rotation.

Sedge, particularly Saw Sedge (Cladium mariscus), is harvested in summer. It is still used for thatching. In the past it would have covered the entire roof, nowadays it is used only along the ridge. Other uses for sedge included use as a floor covering and to light fires.

Common Reed (Phragmites communis) is another valuable crop from Wicken. The harvesting of reed has only been carried out since 1960. It is also used as a thatching material and is used on the sides (pitch) of the roof. The reedbeds are at the far west part of Adventurer's Fen.

Litter, is cut each year in all seasons except winter. It is made up of a wide variety of grasses and herbs and was traditionally used for bedding and fodder for cattle. Most modern cattle will not to eat such rough hay, and so much litter is piled up in heaps to rot. Some local farmers still buy litter, and in 1996 several bales were bought by a nearby nature reserve to provide a seed source for a newly planted area.

Other important management activities include slubbing out ditches and dykes; scientific monitoring; path repairs; boardwalk maintenance; scrub clearance; and many other occasional duties.